Search results for: titanium implants

Authors: Saarah Juman, Ilona Johnson, Stephen Richmond, Brett Duane, Sheelagh Rogers

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Introduction: Researchers suggest that within 50 years or less, the available supply of a range of metals will be exhausted, potentially leading to increases in resource conflict and largescale production shortages. The healthcare, dental and orthodontic sectors will undoubtedly be affected as stainless steel instruments are generally heavily relied on. Although changing orthodontic archwires are unavoidable and necessary to allow orthodontic tooth movement through the progression of an archwire sequence with fixed appliances, they are thought to be manufactured in excess of what is needed. Furthermore, orthodontic archwires require trimming extraorally to allow safe intraoral insertion, thus contributing to unnecessary waste of natural resources. Currently, there is no evidence to support the optimisation of archwire length according to orthodontic fixed appliance stage. As such, this study aims to quantify archwire excess (extraoral archwire trimmings) for different stages of orthodontic fixed appliance treatment. Methodology: This prospective, observational, quantitative study observed trimmings made extraorally against pre-treatment study models by clinicians over a 3-month period. Archwires were categorised into one of three categories (initial aligning, sequence, working/finishing arcwhires) within the orthodontic fixed appliance archwire sequence. Data collection included archwire material composition and the corresponding length and weight of excess archwire. Data was entered using a Microsoft Excel spreadsheet and imported into statistical software to obtain simple descriptive statistics. Results: Measurements were obtained for a total of 144 archwires. Archwire materials included nickel titanium and stainless steel. All archwires observed required extraorally trimming to allow safe intraoral insertion. The manufactured lengths of orthodontic initial aligning, sequence, and working/finishing arcwhires were at least 31%, 26%, and 39% in excess, respectively. Conclusions: Orthodontic archwires are manufactured to be excessively long at all orthodontic archwire sequence stages. To conserve natural resources, this study’s findings support the optimisation of orthodontic archwire lengths by manufacturers according to the typical stages of an orthodontic archwire sequence.

Keywords: archwire, orthodontics, sustainability, waste

Procedia PDF Downloads 195

Authors: Ádám Vass, István Bakos, Irina Borbáth, Zoltán Pászti, István Sajó, András Tompos

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Important requirements for the anode side electrocatalysts of polymer electrolyte membrane (PEM) fuel cells are CO-tolerance, stability and corrosion resistance. Carbon is still the most common material for electrocatalyst supports due to its low cost, high electrical conductivity and high surface area, which can ensure good dispersion of the Pt. However, carbon becomes degraded at higher potentials and it causes problem during application. Therefore it is important to explore alternative materials with improved stability. Molybdenum-oxide can improve the CO-tolerance of the Pt/C catalysts, but it is prone to leach in acidic electrolyte. The Mo was stabilized by isovalent substitution of molybdenum into the rutile phase titanium-dioxide lattice, achieved by a modified multistep sol-gel synthesis method optimized for preparation of Ti0.7Mo.3O2-C composite. High degree of Mo incorporation into the rutile lattice was developed. The conductivity and corrosion resistance across the anticipated potential/pH window was ensured by mixed oxide – activated carbon composite. Platinum loading was carried out using NaBH4 and ethylene glycol; platinum content was 40 wt%. The electrocatalyst was characterized by both material investigating methods (i.e. XRD, TEM, EDS, XPS techniques) and electrochemical methods (cyclic-voltammetry, COads stripping voltammetry, hydrogen oxidation reaction on rotating disc electrode). The electrochemical activity of the sample was compared to commercial 40 wt% Pt/C (Quintech) and PtRu/C (Quintech, Pt= 20 wt%, Ru= 10 wt%) references. Enhanced CO tolerance of the electrocatalyst prepared using the Ti0.7Mo.3O2-C composite material was evidenced by the appearance of a CO-oxidation related 'pre-peak' and by the pronounced shift of the maximum of the main CO oxidation peak towards less positive potential compared to Pt/C. Fuel cell polarization measurements were also carried out using Bio-Logic and Paxitech FCT-150S test device. All details on the design, preparation, characterization and testing by both electrochemical measurements and fuel cell test device of electrocatalyst supported on Ti0.7Mo.3O2-C composite material will be presented and discussed.

Keywords: anode electrocatalyst, composite material, CO-tolerance, TiMoOx

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Authors: Görkem Cemali̇, Avram Aruh, Gamze Torun Köse, Erde Can ŞAfak

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In order to heal bone disorders, the conventional methods which involve the use of autologous and allogenous bone grafts or permanent implants have certain disadvantages such as limited supply, disease transmission, or adverse immune response. A biodegradable material that acts as structural support to the damaged bone area and serves as a scaffold that enhances bone regeneration and guides bone formation is one desirable solution. Poly(propylene fumarate) (PPF) which is an unsaturated polyester that can be copolymerized with appropriate vinyl monomers to give biodegradable network structures, is a promising candidate polymer to prepare bone tissue engineering scaffolds. In this study, hydroxyl-terminated PPF was synthesized and thermally cured with vinyl phosphonic acid (VPA) and diethyl vinyl phosphonate (VPES) in the presence of radical initiator benzoyl peroxide (BP), with changing co-monomer weight ratios (10-40wt%). In addition, the synthesized PPF was cured with VPES comonomer at body temperature (37oC) in the presence of BP initiator, N, N-Dimethyl para-toluidine catalyst and varying amounts of Beta-tricalcium phosphate (0-20 wt% ß-TCP) as filler via radical polymerization to prepare composite materials that can be used in injectable forms. Thermomechanical properties, compressive properties, hydrophilicity and biodegradability of the PPF/VPA and PPF/VPES copolymers were determined and analyzed with respect to the copolymer composition. Biocompatibility of the resulting polymers and their composites was determined by the MTS assay and osteoblast activity was explored with von kossa, alkaline phosphatase and osteocalcin activity analysis and the effects of VPA and VPES comonomer composition on these properties were investigated. Thermally cured PPF/VPA and PPF/VPES copolymers with different compositions exhibited compressive modulus and strength values in the wide range of 10–836 MPa and 14–119 MPa, respectively. MTS assay studies showed that the majority of the tested compositions were biocompatible and the overall results indicated that PPF/VPA and PPF/VPES network polymers show significant potential for applications as bone tissue engineering scaffolds where varying PPF and co-monomer ratio provides adjustable and controllable properties of the end product. The body temperature cured PPF/VPES/ß-TCP composites exhibited significantly lower compressive modulus and strength values than the thermal cured PPF/VPES copolymers and were therefore found to be useful as scaffolds for cartilage tissue engineering applications.

Keywords: biodegradable, bone tissue, copolymer, poly(propylene fumarate), scaffold

Procedia PDF Downloads 166

Authors: Seydou Drabo

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This paper examines how traditional contraceptives and abortion practices challenges the use of modern contraceptives in Burkina Faso. It demonstrates how fears and ‘superstitions’ interact with knowledge about modern contraceptives methods to determine use in a context where other way of controlling fertility (traditional contraceptives, abortion) are available to women in the public, private and traditional health sectors. Furthermore, these issues come at the time when Burkina Faso is among countries with a high fertility rate which (6.0 in 2010) and a very low used of contraceptives as only 16% of married women of childbearing age were using a contraceptive method in 2010. The country also has a young population since 33 % of the population is between 10-24 years old and this number is expected to increase by 2050, generating fears that a growing population of youth will put excessive pressure on available resources, including access to education, health services, and employment. Despite over two decades of dedicated policy attention, 24% of women of reproductive age (15-49) was estimated to have an unmet need for contraception in 2010. This paper draws on ethnographic fieldwork conducted since march 2016 (The research is still in progress) in Burkina Faso. Data were collected from 25 women (users and non-users of modern contraceptives and /or traditional contraceptives, post abortion care patients), 4 street drugs vendors and 3 traditional healers through formal and informal interviews, as well as direct observation. The findings show that a variety of contraceptives methods and abortion drugs or methods, both traditional and modern circulate and are available to women. Traditional contraceptives called African contraceptives by some of our participants refer to several birth control method including plants decoction, magical ring, waist necklace, a ritual done with a mixture of lay coming from termite mound and menses. Abortion is a practice that is done in secret through the use of abortion drugs or through intra uterine manoeuvres. Modern contraceptives include Oral contraceptive, implants, injectable. Stereotypes about modern contraceptives, having regular menstrual cycles and adopt of natural birth control methods, bad experience with modern contraceptives methods, the side effect of modern contraceptives, irregularity of sexual activities and the availability of emergency contraceptives are among factors that limit their use among women. In addition, a negative perception is built around modern contraceptives seen as the drug of ‘white people’. In general, the information on these drugs circulates in women’s social network (first line of information on contraceptive). Some women prefer using what they call African contraceptives or inducing an abortion over modern contraceptives because of their side effect. Furthermore, the findings show that women practices and attitudes in controlling birth varies throughout different phases of their lives. Beyond global discourses and technical solution, the issue of Family planning is all about social practices.

Keywords: abortion, Burkina Faso, contraception, culture, women

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Authors: Anne Mastamet-Mason

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Crimes against women is a global concern, and South Africa, in particular, is in a dilemma of dealing with constant criminal acts that face the country. Debates on violence against women in South Africa cannot be overemphasised any longer as crimes continue to rise year by year. The recent death of a university student at the University of Cape Town, as well as many other cases, continues to strengthen the need to find solutions from all the spheres of South African society. The advanced textiles market contains a high number and variety of technologies, many of which have protected status and constitute a relatively small portion of the textiles used for the consumer market. Examples of advanced textiles include nanomaterials, such as silver, titanium dioxide and zinc oxide, designed to create an anti-microbial and self-cleaning layer on top of the fibers, thereby reducing body smell and soiling. Smart textiles propose materials and fabrics versatile and adaptive to different situations and functions. Integrating textiles and computing technologies offer an opportunity to come up with differentiated characteristics and functionality. This paper presents a proposal to design a smart camisole/Yoga sports brazier and a smart Yoga sports pant garment to be worn by women while alone and while in purported danger zones. The smart garments are to be worn under normal clothing and cannot be detected or seen, or suspected by perpetrators. The garments are imbued with devices to sense any physical aggression and any abnormal or accelerated heartbeat that may be exhibited by the victim of violence. The signals created during the attack can be transmitted to the police and family members who own a mobile application system that accepts signals emitted. The signals direct the receiver to the exact location of the offence, and the victim can be rescued before major violations are committed. The design of the Yoga sports garments will be done by Professor Mason, who is a fashion designer by profession, while the mobile phone application system will be developed by Mr. Amos Yegon, who is an independent software developer.

Keywords: smart clothing, wearable technology, south africa, 4th industrial revolution

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Authors: H. Bhuyan, S. Mändl, M. Favre, M. Cisternas, A. Henriquez, E. Wyndham, M. Walczak, D. Manova

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The 470 Li-24 Cr and 460Li-21 Cr are two alloys belonging to the next generation of super-ferritic nickel free stainless steel grades, containing titanium (Ti), niobium (Nb) and small percentage of carbon (C) and nitrogen (N). The addition of Ti and Nb improves in general the corrosion resistance while the low interstitial content of C and N assures finer precipitates and greater ductility compared to conventional ferritic grades. These grades are considered an economic alternative to AISI 316L and 304 due to comparable or superior corrosion. However, since 316L and 304 can be nitrided to improve the mechanical surface properties like hardness and wear; it is hypothesize that the tribological properties of these super-ferritic stainless steels grades can also be improved by plasma nitriding. Thus two sets of plasma immersion ion implantation experiments have been carried out, one with a high pressure capacitively coupled radio frequency plasma at PUC Chile and the other using a low pressure microwave plasma at IOM Leipzig, in order to explore further improvements in the mechanical properties of 470 Li-24 Cr and 460Li-21 Cr steel. Nitrided and unnitrided substrates have been subsequently investigated using different surface characterization techniques including secondary ion mass spectroscopy, scanning electron microscopy, energy dispersive x-ray analysis, Vickers hardness, wear resistance, as well as corrosion test. In most of the characterizations no major differences have been observed for nitrided 470 Li-24 Cr and 460Li-21 Cr. Due to the ion bombardment, an increase in the surface roughness is observed for higher treatment temperature, independent of the steel types. The formation of chromium nitride compound takes place only at a treatment temperature around 4000C-4500C, or above. However, corrosion properties deteriorate after treatment at higher temperatures. The physical characterization results show up to 25 at.% of nitrogen for a diffusion zone of 4-6 m, and a 4-5 times increase in hardness for different experimental conditions. The samples implanted with temperature higher than 400 °C presented a wear resistance around two orders of magnitude higher than the untreated substrates. The hardness is apparently affected by the different roughness of the samples and their different profile of nitrogen.

Keywords: ion implantation, plasma, RF and microwave plasma, stainless steel

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Authors: Kumaran Letchmanan, Shou-Cang Shen, Wai Kiong Ng

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Postoperative implant-associated infections in soft tissues and bones remain a serious complication in orthopaedic surgery, which leads to impaired healing, re-implantation, prolong hospital stay and increase cost. Drug-loaded implants with sustained release of antibiotics at the local site are current research interest to reduce the risk of post-operative infections and osteomyelitis, thus, minimize the need for follow-up care and increase patient comfort. However, the improved drug release of the drug-loaded bone cements is usually accompanied by a loss in mechanical strength, which is critical for weight-bearing bone cement. Recently, more attempts have been undertaken to develop techniques to enhance the antibiotic elution as well as preserve the mechanical properties of the bone cements. The present study investigates the potential influence of addition of mesoporous silica nanoparticles (MSN) on the in vitro drug release kinetics of gentamicin (GTMC), along with the mechanical properties of bone cements. Simplex P was formulated with MSN and loaded with GTMC by direct impregnation. Meanwhile, Simplex P with water soluble poragen (xylitol) and high loading of GTMC as well as commercial bone cement CMW Smartset GHV were used as controls. MSN-formulated bone cements are able to increase the drug release of GTMC by 3-fold with a cumulative release of more than 46% as compared with other control groups. Furthermore, a sustained release could be achieved for two months. The loaded nano-sized MSN with uniform pore channels significantly build up an effective nano-network path in the bone cement facilitates the diffusion and extended release of GTMC. Compared with formulations using xylitol and high GTMC loading, incorporation of MSN shows no detrimental effect on biomechanical properties of the bone cements as no significant changes in the mechanical properties as compared with original bone cement. After drug release for two months, the bending modulus of MSN-formulated bone cements is 4.49 ± 0.75 GPa and the compression strength is 92.7 ± 2.1 MPa (similar to the compression strength of Simplex-P: 93.0 ± 1.2 MPa). The unaffected mechanical properties of MSN-formulated bone cements was due to the unchanged microstructures of bone cement, whereby more than 98% of MSN remains in the matrix and supports the bone cement structures. In contrast, the large portions of extra voids can be observed for the formulations using xylitol and high drug loading after the drug release study, thus caused compressive strength below the ASTM F541 and ISO 5833 minimum of 70 MPa. These results demonstrate the potential applicability of MSN-functionalized poly(methyl methacrylate)-based bone cement as a highly efficient, sustained and local drug delivery system with good mechanical properties.

Keywords: antibiotics, biomechanical properties, bone cement, sustained release

Procedia PDF Downloads 257

Authors: Ioannis Panagiotopoulos, Aristidis Anastasakis, Konstantinos Toutouzas, Ioannis Iakovou, Charalampos Vlachopoulos, Vasilis Voudris, Georgios Tziomalos, Konstantinos Tsioufis, Efstathios Kastritis, Alexandros Briassoulis, Kimon Stamatelopoulos, Alexios Antonopoulos, Paraskevi Exadaktylou, Evanthia Giannoula, Anastasia Katinioti, Maria Kalantzi, Evangelos Leontiadis, Eftychia Smparouni, Ioannis Malakos, Nikolaos Aravanis, Argyrios Doumas, Maria Koutelou

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Introduction: Cardiac amyloidosis from Transthyretin (ATTR-CA) is an infiltrative disease characterized by the deposition of pathological transthyretin complexes in the myocardium. This study describes the characteristics of patients diagnosed with ATTR-CA from 2019 until present at the Nuclear Medicine Department of Onassis Cardiac Surgery Center and AHEPA Hospital. These centers have extensive experience in amyloidosis and modern technological equipment for its diagnosis. Materials and Methods: Records of consecutive patients (N=73) diagnosed with any type of amyloidosis were collected, analyzed, and prospectively followed. The diagnosis of amyloidosis was made using specific myocardial scintigraphy with Tc-99m DPD. Demographic characteristics, including age, gender, marital status, height, and weight, were collected in a database. Clinical characteristics, such as amyloidosis type (ATTR and AL), serum biomarkers (BNP, troponin), electrocardiographic findings, ultrasound findings, NYHA class, aortic valve replacement, device implants, and medication history, were also collected. Some of the most significant results are presented. Results: A total of 73 cases (86% male) were diagnosed with amyloidosis over four years. The mean age at diagnosis was 82 years, and the main symptom was dyspnea. Most patients suffered from ATTR-CA (65 vs. 8 with AL). Out of all the ATTR-CA patients, 61 were diagnosed with wild-type and 2 with two rare mutations. Twenty-eight patients had systemic amyloidosis with extracardiac involvement, and 32 patients had a history of bilateral carpal tunnel syndrome. Four patients had already developed polyneuropathy, and the diagnosis was confirmed by DPD scintigraphy, which is known for its high sensitivity. Among patients with isolated cardiac involvement, only 6 had left ventricular ejection fraction below 40%. The majority of ATTR patients underwent tafamidis treatment immediately after diagnosis. Conclusion: In conclusion, the experiences shared by the two centers and the continuous exchange of information provide valuable insights into the diagnosis and management of cardiac amyloidosis. Clinical suspicion of amyloidosis and early diagnostic approach are crucial, given the availability of non-invasive techniques. Cardiac scintigraphy with DPD can confirm the presence of the disease without the need for a biopsy. The ultimate goal still remains continuous education and awareness of clinical cardiologists so that this systemic and treatable disease can be diagnosed and certified promptly and treatment can begin as soon as possible.

Keywords: amyloidosis, diagnosis, myocardial scintigraphy, Tc-99m DPD, transthyretin

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Authors: S. Gariani, I. Shyha

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Cutting titanium alloys are usually accompanied with low productivity, poor surface quality, short tool life and high machining costs. This is due to the excessive generation of heat at the cutting zone and difficulties in heat dissipation due to relatively low heat conductivity of this metal. The cooling applications in machining processes are crucial as many operations cannot be performed efficiently without cooling. Improving machinability, increasing productivity, enhancing surface integrity and part accuracy are the main advantages of cutting fluids. Conventional fluids such as mineral oil-based, synthetic and semi-synthetic are the most common cutting fluids in the machining industry. Although, these cutting fluids are beneficial in the industries, they pose a great threat to human health and ecosystem. Vegetable oils (VOs) are being investigated as a potential source of environmentally favourable lubricants, due to a combination of biodegradability, good lubricous properties, low toxicity, high flash points, low volatility, high viscosity indices and thermal stability. Fatty acids of vegetable oils are known to provide thick, strong, and durable lubricant films. These strong lubricating films give the vegetable oil base stock a greater capability to absorb pressure and high load carrying capacity. This paper details preliminary experimental results when turning Ti-6Al-4V. The impact of various VO-based cutting fluids, cutting tool materials, working conditions was investigated. The full factorial experimental design was employed involving 24 tests to evaluate the influence of process variables on average surface roughness (Ra), tool wear and chip formation. In general, Ra varied between 0.5 and 1.56 µm and Vasco1000 cutting fluid presented comparable performance with other fluids in terms of surface roughness while uncoated coarse grain WC carbide tool achieved lower flank wear at all cutting speeds. On the other hand, all tools tips were subjected to uniform flank wear during whole cutting trails. Additionally, formed chip thickness ranged between 0.1 and 0.14 mm with a noticeable decrease in chip size when higher cutting speed was used.

Keywords: cutting fluids, turning, Ti-6Al-4V, vegetable oils, working conditions

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Authors: Geliashvili T. M., Tyulyandina A. S., Valiev A. K., Kononets P. V., Kharatishvili T. K., Salkov A. G., Pronin A. I., Gadzhieva E. H., Parnas A. V., Ilyakov V. S.

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Aim/Introduction: Metastasis (Mts) to the sternum, while extremely rare in differentiated thyroid cancer (DTC) (1), requires a personalized, multidisciplinary treatment approach. In aggressively growing Mts to the sternum, which rapidly become unresectable, a comprehensive therapeutic and diagnostic approach is particularly important. Materials and methods: We present a clinical case of solitary Mts to the sternum as first manifestation of a papillary thyroid microcarcinoma in a 55-year-old man. Results: 18F-FDG PET/CT after thyroidectomy confirmed the solitary Mts to the sternum with extremely high FDG uptake (SUVmax=71,1), which predicted its radioiodine-refractory (RIR). Due to close attachment to the mediastinum and rapid growth, Mts was considered unresectable. During the next three months, the patient received targeted therapy with the tyrosine kinase inhibitor (TKI) Lenvatinib 24 mg per day. 1st course of radioiodine therapy (RIT) 6 GBq was also performed, the results of which confirmed the RIR of the tumor process. As a result of systemic therapy (targeted therapy combined with RIT and suppressive hormone therapy with L-thyroxine), there was a significant biochemical response (decrease of serum thyroglobulin level from 50,000 ng/ml to 550 ng/ml) and a partial response with decrease of tumor size (from 80x69x123 mm to 65x50x112 mm) and decrease of FDG accumulation (SUVmax from 71.1 to 63). All of this made possible to perform surgical treatment of Mts - sternal extirpation with its replacement by an individual titanium implant. At the control examination, the stimulated thyroglobulin level was only 134 ng/ml, and PET/CT revealed postoperative areas of 18F-FDG metabolism in the removed sternal Mts. Also, 18F-FDG PET/CT in the early (metabolic) stage revealed two new bone Mts (in the area of L3 SUVmax=17,32 and right iliac bone SUVmax=13,73), which, as well as the removed sternal Mts, appeared to be RIRs at the 2nd course of RIT 6 GBq. Subsequently, on 02.2022, external beam radiation therapy (EBRT) was performed on the newly identified oligometastatic bone foci. At present, the patient is under dynamic monitoring and in the process of suppressive hormone therapy with L-thyroxine. Conclusion: Thus, only due to the early prescription of targeted TKI therapy was it possible to perform surgical resection of Mts to the sternum, thereby improve the patient's quality of life and preserve the possibility of radical treatment in case of oligometastatic disease progression.

Keywords: differentiated thyroid cancer, metastasis to the sternum, radioiodine therapy, radioiodine-refractory cancer, targeted therapy, lenvatinib

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Authors: Josiane Yaguibou, Ngoy Kishimba, Issiaka V. Coulibaly, Sabrina Pestilli, Falinirina Razanalison, Hantanirina V. Andremanisa

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Background In Madagascar modern contraceptive prevalence rate increased from 18% in 2003 to 43% in 2021. Anecdotal evidence suggests that increased use and frequent stock out in public health facilities of male condoms and medroxyprogesterone acetate (MPA) can be related to diverted use of these products. This study analyzed the use of contraceptives and mode of utilization (correct or diverted) at the community level in the period 2019-2023 in Madagascar. Methodology: The study included a literature review, a quantitative survey combined with a qualitative study. It was carried out in 10 regions out of the 23 of the country. Eight regions (Bongolava, Vakinakaratra, Italy, Hautre Matsiatra, Betsiboka, Diana, Sofia and Anosy) were selected based on a study that showed existence of medroxyprogesterone acetate in pigs (MPA). The remaining 2 regions were selected due to high mCPR (Atsimo Andrefana) and to ensure coverage of all geographical zones in the country (Alaotra Mangoro). Sample random method was used, and the sample size was identified at 300 individuals per region. Zonal distribution is based on the urbanization rate for the region. 6 focus group discussions were organized in 3 regions, equally distributed between rural and urban areas. Key findings: Overall, 67% of those surveyed or their partner are currently using contraception. Injectables (MPA) are the most popular choice (33%), followed by implants and male condoms, 12% and 9%, respectively. The majority of respondents use condoms to prevent unwanted pregnancy but also to prevent STDs. Still, 43% of respondents use condoms for other purposes, reaching 52% of respondents in urban areas and 71,2% in the age group 15-18. Diverted use includes hair growth (18.9%), as a toy (18.8%), cleaning the screen of electronic devices (10 %), cleaning shoes (3.1%) and for skincare (1.6%). Injectables are the preferred method of contraception both in rural areas (35%) and urban areas (21.2%). However, diverted use of injectables was confirmed by 4% of the respondents, ranging from 3 % in rural areas to 12% in urban. The diverted use of injectables in pig rearing was to avoid pregnancy and facilitate pig’s growth. Program Implications: The study confirmed the diverted use of some contraceptives. The misuse of male condoms is among the causes of stockouts of products in public health facilities, limiting their availability for pregnancy and STDs prevention. The misuse of injectables in pigs rearing needs to be further studied to learn the full extent of the misuse and eventual implications for meat consumption. The study highlights the importance of including messages on the correct use of products during sensibilization activities. In particular, messages need to address the anecdotal and false effects of male condoms, especially amongst young people. For misuse of injectables is critical to sensibilize farmers and veterinaries on possible negative effects for humans.

Keywords: diverted use, injectables, male condoms, sensibilization

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Authors: Vladimir Hovhannisyan, Chen Yuan Dong

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Recently nanoparticles (NPs) have been introduced in biomedicine as effective agents for cancer-targeted drug delivery and noninvasive tissue imaging. The most important requirements to these agents are their non-toxicity, biocompatibility and stability. In view of these criteria, the zeolite (ZL) nanoparticles (NPs) may be considered as perfect candidates for biomedical applications. ZLs are crystalline aluminosilicates consisting of oxygen-sharing SiO4 and AlO4 tetrahedral groups united by common vertices in three-dimensional framework and containing pores with diameters from 0.3 to 1.2 nm. Generally, the behavior and physical properties of ZLs are studied by SEM, X-ray spectroscopy, and AFM, whereas optical spectroscopic and microscopic approaches are not effective enough, because of strong scattering in common ZL bulk materials and powders. The light scattering can be reduced by using of ZL NPs. ZL NPs have large external surface area, high dispersibility in both aqueous and organic solutions, high photo- and thermal stability, and exceptional ability to adsorb various molecules and atoms in their nanopores. In this report, using multiphoton microscopy and nonlinear spectroscopy, we investigate nonlinear optical properties of clinoptilolite type of ZL micro- and nanoparticles with average diameters of 2200 nm and 240 nm, correspondingly. Multiphoton imaging is achieved using a laser scanning microscope system (LSM 510 META, Zeiss, Germany) coupled to a femtosecond titanium:sapphire laser (repetition rate- 80 MHz, pulse duration-120 fs, radiation wavelength- 720-820 nm) (Tsunami, Spectra-Physics, CA). Two Zeiss, Plan-Neofluar objectives (air immersion 20×∕NA 0.5 and water immersion 40×∕NA 1.2) are used for imaging. For the detection of the nonlinear response, we use two detection channels with 380-400 nm and 435-700 nm spectral bandwidths. We demonstrate that ZL micro- and nanoparticles can produce nonlinear optical response under the near-infrared femtosecond laser excitation. The interaction of hypericine, chlorin e6 and other dyes with ZL NPs and their photodynamic activity is investigated. Particularly, multiphoton imaging shows that individual ZL NPs particles adsorb Zn-tetraporphyrin molecules, but do not adsorb fluorescein molecules. In addition, nonlinear spectral properties of ZL NPs in native biotissues are studied. Nonlinear microscopy and spectroscopy may open new perspectives in the research and application of ZL NP in biomedicine, and the results may help to introduce novel approaches into the clinical environment.

Keywords: multiphoton microscopy, nanoparticles, nonlinear optics, zeolite

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Authors: Balthazar Temu, Zhao Yan, Bogdan-Petrin Ratiu, Sang Soon Oh, Qiang Li

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Photonic crystal surface emitting lasers (PCSELs) has recently become an area of active research because of the advantages these lasers have over the edge emitting lasers and vertical cavity surface emitting lasers (VCSELs). PCSELs can emit laser beams with high power (from the order of few milliwatts to Watts or even tens of Watts) which scales with the emission area while maintaining single mode operation even at large emission areas. Most PCSELs reported in the literature are air-hole based, with only few demonstrations of nanowire based PCSELs. We previously reported an optically pumped, nanowire based PCSEL operating in the O band by using the honeycomb lattice. The nanowire based PCSELs have the advantage of being able to grow on silicon platform without threading dislocations. It is desirable to extend their operating wavelength to C band to open more applications including eye-safe sensing, lidar and long haul optical communications. In this work we first analyze how the lattice constant , nanowire diameter, nanowire height and side length of the hexagon in the honeycomb pattern can be changed to increase the operating wavelength of the honeycomb based PCSELs to the C band. Then as an attempt to make our device electrically pumped, we present the finite-difference time-domain (FDTD) simulation results with metals on the nanowire. The results for different metals on the nanowire are presented in order to choose the metal which gives the device with the best quality factor. The metals under consideration are those which form good ohmic contact with p-type doped InGaAs with low contact resistivity and decent sticking coefficient to the semiconductor. Such metals include Tungsten, Titanium, Palladium and Platinum. Using the chosen metal we demonstrate the impact of thickness of the metal for a given nanowire height on the quality factor of the device. We also investigate how the height of the nanowire affects the quality factor for a fixed thickness of the metal. Finally, the main steps in making the practical device are discussed.

Keywords: designing nanowire PCSEL, designing PCSEL on silicon substrates, low threshold nanowire laser, simulation of photonic crystal lasers.

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Authors: Amit Mallik, Anil K. Barik, Biswajit Pal

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The galloping advancement of research work on glass-ceramics stems from their wide applications in electronic industry and also to some extent in application oriented medical dentistry. TiO2, even in low concentration has been found to strongly influence the physical and mechanical properties of the glasses. Glass-ceramics is a polycrystalline ceramic material produced through controlled crystallization of glasses. Crystallization is accomplished by subjecting the suitable parent glasses to a regulated heat treatment involving the nucleation and growth of crystal phases in the glass. Mica glass-ceramics is a new kind of glass-ceramics based on the system SiO2•MgO•K2O•F. The predominant crystalline phase is synthetic fluormica, named fluorophlogopite. Mica containing glass-ceramics flaunt an exceptional feature of machinability apart from their unique thermal and chemical properties. Machinability arises from the randomly oriented mica crystals with a 'house of cards' microstructures allowing cracks to propagate readily along the mica plane but hindering crack propagation across the layers. In the present study, we have systematically investigated the crystallization, microstructure and mechanical behavior of barium fluorophlogopite mica-containing glass-ceramics of composition BaO•4MgO•Al2O3•6SiO2•2MgF2 nucleated by addition of 2, 4, 6 and 8 wt% TiO2. The glass samples were prepared by the melting technique. After annealing, different batches of glass samples for nucleation were fired at 730°C (2wt% TiO2), 720°C (4 wt% TiO2), 710°C (6 wt% TiO2) and 700°C (8 wt% TiO2) batches respectively for 2 h and ultimately heated to corresponding crystallization temperatures. The glass batches were analyzed by differential thermal analysis (DTA) and x-ray diffraction (XRD), scanning electron microscopy (SEM) and micro hardness indenter. From the DTA study, it is found that the fluorophlogopite mica crystallization exotherm appeared in the temperature range 886–903°C. Glass transition temperature (Tg) and crystallization peak temperature (Tp) increased with increasing TiO2 content up to 4 wt% beyond this weight% the glass transition temperature (Tg) and crystallization peak temperature (Tp) start to decrease with increasing TiO2 content up to 8 wt%. Scanning electron microscopy confirms the development of an interconnected ‘house of cards’ microstructure promoted by TiO2 as a nucleating agent. The increase in TiO2 content decreases the vicker’s hardness values in glass-ceramics.

Keywords: crystallization, fluormica glass, ‘house of cards’ microstructure, hardness

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Authors: Wenhao Li, Shijun Guo

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Carbon fibre reinforced composites are progressively replacing metal structures in modern civil aircraft. This is because composite materials have large potential of weight saving compared with metal. However, the achievement to date of weight saving in composite structure is far less than the theoretical potential due to many uncertainties in structural integrity and safety concern. Unlike the conventional metallic structure, composite components are bonded together along the joints where structural integrity is a major concern. To ensure the safety, metal fasteners are used to reinforce the composite bonded joints. One of the solutions for a significant weight saving of composite structure is to develop an effective technology of on-board Structural Health Monitoring (SHM) System. By monitoring the real-life stress status of composite structures during service, the safety margin set in the structure design can be reduced with confidence. It provides a means of safeguard to minimize the need for programmed inspections and allow for maintenance to be need-driven, rather than usage-driven. The aim of this paper is to develop smart composite joint. The key technology is a multifunctional thermoplastic composite fastener (MTCF). The MTCF will replace some of the existing metallic fasteners in the most concerned locations distributed over the aircraft composite structures to reinforce the joints and form an on-board SHM network system. Each of the MTCFs will work as a unit of the AU and AE technology. The proposed MTCF technology has been patented and developed by Prof. Guo in Cranfield University, UK in the past a few years. The manufactured MTCF has been successfully employed in the composite SLJ (Single-Lap Joint). In terms of the structure integrity, the hybrid SLJ reinforced by MTCF achieves 19.1% improvement in the ultimate failure strength in comparison to the bonded SLJ. By increasing the diameter or rearranging the lay-up sequence of MTCF, the hybrid SLJ reinforced by MTCF is able to achieve the equivalent ultimate strength as that reinforced by titanium fastener. The predicted ultimate strength in simulation is in good agreement with the test results. In terms of the structural health monitoring, a signal from the MTCF was measured well before the load of mechanical failure. This signal provides a warning of initial crack in the joint which could not be detected by the strain gauge until the final failure.

Keywords: composite single-lap joint, crack propagation, multifunctional composite fastener, structural health monitoring

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Authors: Arezoo Rahmani, Rinez Thapa, Juha-Matti Aalto, Petri Turhanen, Jouko Vepsalainen, Vesa-PekkaLehto, Joakim Riikonen

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Production of Scandium (Sc) is a complicated process because Sc is found only in low concentrations in ores and the concentration of Sc is very low compared with other metals. Therefore, utilization of typical extraction processes such as solvent extraction is problematic in scandium extraction. The Adsorption/desorption method can be used, but it is challenging to prepare materials, which have good selectivity, high adsorption capacity, and high stability. Therefore, efficient and environmentally friendly methods for Sc extraction are needed. In this study, the nanoporous composite material was developed for extracting Sc from an Sc ore. The nanoporous composite material offers several advantageous properties such as large surface area, high chemical and mechanical stability, fast diffusion of the metals in the material and possibility to construct a filter out of the material with good flow-through properties. The nanoporous silicon material was produced by first stabilizing the surfaces with a silicon carbide layer and then functionalizing the surface with bisphosphonates that act as metal chelators. The surface area and porosity of the material were characterized by N₂ adsorption and the morphology was studied by scanning electron microscopy (SEM). The bisphosphonate content of the material was studied by thermogravimetric analysis (TGA). The concentration of metal ions in the adsorption/desorption experiments was measured with inductively coupled plasma mass spectrometry (ICP-MS). The maximum capacity of the material was 25 µmol/g Sc at pH=1 and 45 µmol/g Sc at pH=3, obtained from adsorption isotherm. The selectivity of the material towards Sc in artificial solutions containing several metal ions was studied at pH one and pH 3. The result shows good selectivity of the nanoporous composite towards adsorption of Sc. Scandium was less efficiently adsorbed from solution leached from the ore of Sc because of excessive amounts of iron (Fe), aluminum (Al) and titanium (Ti) which disturbed the adsorption process. For example, the concentration of Fe was more than 4500 ppm, while the concentration of Sc was only three ppm, approximately 1500 times lower. Precipitation methods were developed to lower the concentration of the metals other than Sc. Optimal pH for precipitation was found to be pH 4. The concentration of Fe, Al and Ti were decreased by 99, 70, 99.6%, respectively, while the concentration of Sc decreased only 22%. Despite the large reduction in the concentration of other metals, more work is needed to further increase the relative concentration of Sc compared with other metals to efficiently extract it using the developed nanoporous composite material. Nevertheless, the developed material may provide an affordable, efficient and environmentally friendly method to extract Sc on a large scale.

Keywords: adsorption, nanoporous silicon, ore solution, scandium

Procedia PDF Downloads 146

Authors: Shivani Thakur, Jasmin Dominguez Cervantes, Ahmed Zabiba, Fatima Zabiba, Sandhini Agarwal, Kamalpreet Kaur, Hussein Maatouk, Shae Chand, Omar Madriz, Tiffany Huang, Saloni Bansal

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Contraceptives are an effective public health achievement, allowing for family planning and reducing the risk of sexually transmitted diseases (STDs). California’s rural Central Valley has high rates of teenage pregnancy and STDs. Factors affecting contraceptive usage here may include religious concerns, financial issues, and regional variations in the accessibility and availability of contraceptives. The increasing population and diversity of the Central Valley make the understanding of the determinants of unintended pregnancy and STDs increasingly nuanced. Patients in California’s Central Valley were surveyed at 6 surgical clinics to assess attitudes toward contraceptives. The questionnaire consisted of demographics and 14 Likert-scale statements investigating patients’ feelings regarding contraceptives. Parametric and non-parametric analysis was performed on the Likert statements. A correlation matrix for the Likert-scale statements was used to evaluate the strength of the relationship between each question. 76 patients aged 18-75 years completed the questionnaire. 90% of the participants were female, 76% Hispanic, 36% married, 44% with an income range between 30-60K, and 83% were between childbearing ages. 60% of participants stated they are currently using or had used some type of contraceptive. 25% of participants had at least one unplanned pregnancy. The most common type of contraceptives used were oral contraceptives(28%) and condoms(38%). The top reasons for patients’ contraceptive usage were: prevention of pregnancy (72%), safe sex/prevention of STDs (32%), and regulation of menstrual cycle (19%). Further analysis of Likert responses revealed that contraception usage increased due to approval of contraceptives (x̄=3.98, σ =1.02); partner approval of contraceptives (x̄=3.875, σ =1.16); and reduced anxiety about pregnancy (x̄=3.875, σ =1.23). Younger females (18-34 years old) agreed more with the statement that the cost of contraceptive supplies is too expensive than older females (35-75 years old), (x̄=3.2, σ = 1.4 vs x̄=2.8, σ =1.3, p<0.05). Younger females (44%) were also more likely to use short-acting contraceptive methods (oral and male condoms) compared to older females (64%) who use long-acting methods (implants/ intrauterine devices). 51% of Hispanic females were using some type of contraceptive. Of those Hispanic females who do not use contraceptives, 33% stated having no children, and all plan to have at least one child in the future. 35% of participants had a bachelor's degree. Those with bachelor’s degrees were more likely to use contraceptives, 58% vs 51%, p<0.05, and less likely to have unplanned pregnancy, 50% vs. 12%, p<0.01. There is increasing use and awareness among patients in rural settings concerning contraceptives. Our finding shows that younger women and women with higher educational attainment tend to have more positive attitudes towards the use of contraceptives. This work gives physicians an understanding of patients’ concerns about contraceptive methods and offers insight into culturally competent intervention programs that respect individual values.

Keywords: contraceptives, public health, rural california, women of child baring age

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Authors: Tobias Schnabel

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Naphthalene and naphthalene similar compounds are a common problem in the indoor air of buildings from the 1960s and 1970s in Germany. Often tar containing roof felt was used under the concrete floor to prevent humidity to come through the floor. This tar containing roof felt has high concentrations of PAH (Polycyclic aromatic hydrocarbon) and naphthalene. Naphthalene easily evaporates and contaminates the indoor air. Especially after renovations and energetically modernization of the buildings, the naphthalene concentration rises because no forced air exchange can happen. Because of this problem, it is often necessary to change the floors after renovation of the buildings. The MFPA Weimar (Material research and testing facility) developed in cooperation a project with LEJ GmbH and Reichmann Gebäudetechnik GmbH. It is a technical solution for the disintegration of naphthalene in naphthalene, similar compounds in indoor air with photocatalytic reforming. Photocatalytic systems produce active oxygen species (hydroxyl radicals) through trading semiconductors on a wavelength of their bandgap. The light energy separates the charges in the semiconductor and produces free electrons in the line tape and defect electrons. The defect electrons can react with hydroxide ions to hydroxyl radicals. The produced hydroxyl radicals are a strong oxidation agent, and can oxidate organic matter to carbon dioxide and water. During the research, new titanium oxide catalysator surface coatings were developed. This coating technology allows the production of very porous titan oxide layer on temperature stable carrier materials. The porosity allows the naphthalene to get easily absorbed by the surface coating, what accelerates the reaction of the heterogeneous photocatalysis. The photocatalytic reaction is induced by high power and high efficient UV-A (ultra violet light) Leds with a wavelength of 365nm. Various tests in emission chambers and on the reformer itself show that a reduction of naphthalene in important concentrations between 2 and 250 µg/m³ is possible. The disintegration rate was at least 80%. To reduce the concentration of naphthalene from 30 µg/m³ to a level below 5 µg/m³ in a usual 50 ² classroom, an energy of 6 kWh is needed. The benefits of the photocatalytic indoor air treatment are that every organic compound in the air can be disintegrated and reduced. The use of new photocatalytic materials in combination with highly efficient UV leds make a safe and energy efficient reduction of organic compounds in indoor air possible. At the moment the air cleaning systems take the step from prototype stage into the usage in real buildings.

Keywords: naphthalene, titandioxide, indoor air, photocatalysis

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Authors: Mantas Sriubas, Kristina Bockute, Darius Virbukas, Giedrius Laukaitis

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In this work, the doped TiO2 (dopants – Ca, Mg) was investigated. The comparison between the physical vapour deposition methods as electron beam vapour deposition and magnetron sputtering was performed and the structural and electrical properties of the formed thin films were investigated. Thin films were deposited on different type of substrates: SiO2, Alloy 600 (Fe-Ni-Cr) and Al2O3 substrates. The structural properties were investigated using Ambios XP-200 profilometer, scanning electron microscope (SEM) Hitachi S-3400N, X-ray energy-dispersive spectroscope (EDS) Quad 5040 (Bruker AXS Microanalysis GmbH), X-ray diffractometer (XRD) D8 Discover (Bruker AXS GmbH) with glancing angles focusing geometry in a 20 – 70° range using the Cu Kα1 λ = 0.1540562 nm radiation). The impedance spectroscopy measurements were performed using Probostat® (NorECs AS) measurement cell in the frequency range from 10-1-106 Hz under reducing and oxidizing conditions in temperature range of 200 °C to 1200 °C. The investigation of the e-beam deposited Ca and Mg doped-TiO2 thin films shows that the thin films are dense without any visible pores and cavities and the thin films grow in zone T according Barna-Adamik SZM. Substrate temperature was kept 600 °C during the deposition and Ts/Tm ≈ 0.32 (substrate temperature (Ts) and coating material melting temperature (Tm)). The surface diffusion is high however, the grain boundary migration is strongly limited at this temperature. This means that structure is inhomogeneous and the columnar structure is mostly visible in the upper part of the films. According to XRD, the increasing of the Ca dopants’ concentration increases the crystallinity of the formed thin films and the crystallites size increase linearly and Ca dopants act as prohibitors. Thin films are comprised of anatase TiO2 phase with an exception of 2 % Ca doped TiO2, where a small peak of Ca arise. In the case of Mg doped-TiO2 the intensities of the XRD peaks decreases with increasing Mg molar concentration. It means that there are less diffraction planes of the particular orientation in thin films with higher impurities concentration. Thus, the crystallinity decreases with increasing Mg concentration and Mg dopants act as inhibitors. The impedance measurements show that the dopants changed the conductivity of the formed thin films. The conductivity varies from 10-3 S/cm to 10-4 S/cm at 800 °C under wet reducing conditions. The microstructure of the magnetron sputtered thin TiO2 films is different comparing to the thin films deposited using e-beam deposition therefore influencing other structural and electrical properties.

Keywords: electrical properties, electron beam deposition, magnetron sputtering, microstructure, titanium dioxide

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Authors: Luci V. Hyett

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The criminal law of England and Wales currently deems that a person cannot consent to the infliction of injury upon their own body, where the level of harm is considered to be Actual or Grevious. This renders the defence of consent of the victim as being unavailable to those persons carrying out an Alternative Body Modification procedure. However, the criminalization of consensual injury is more appropriately deemed as being categorized as an offense against public morality and not one against the person, which renders the State’s involvement in the autonomous choices of a consenting adult, when determining what can be done to one’s own body, an arbitrary one. Furthermore, to recognise in law that a person is capable of giving a valid consent to socially acceptable cosmetic interventions that largely consist of procedures designed to aesthetically please men and, not those of people who want to modify their bodies for other reasons means that patriarchal attitudes are continuing to underpin public repulsion and inhibit social acceptance of such practices. Theoretical analysis will begin with a juridical examination of R v M(B) [2019] QB 1 where the High Court determined that Alternative Body Modification was not a special category exempting a person so performing from liability for Grevious Bodily Harm using the defence of consent. It will draw from its reasoning which considered that ‘the removal of body parts were medical procedures being carried out for no medical reason by someone not qualified to carry them out’ which will form the basis of this enquiry. It will consider the philosophical work of Georgio Agamben when analysing whether the biopolitical climate in the UK, which places the optimization of the perfect, healthy body at the centre of political concern can explain why those persons who wish to engage in Alternative Body Modification are treated as the ‘Exception’ to that which is normal using the ‘no medical reason’ canon to justify criminalisation, rather than legitimising the industry through regulation. It will consider, through a feminist lens, the current conflict in law between traditional cosmetic interventions which alter one’s physical appearance for socially accepted aesthetic purposes such as those to the breast, lip and buttock and, modifications described as more outlandish such as earlobe stretching, tooth filing and transdermal implants to create horns and spikes under the skin. It will assert that ethical principles relating to the psychological impact of body modification described as ‘alternative’ is used as a means to exclude person’s seeking such a procedure from receiving safe and competent treatment via a registered cosmetic surgeon which leads to these increasingly popular surgery’s being performed in Tattoo parlours throughout the UK as an extension to other socially acceptable forms of self-modification such as piercings. It will contend that only by ‘inclusive exclusion’ will those ‘othered’ through ostracisation be welcomed into the fold of normality and this can only be achieved through recognition of alternative body modification as a legitimate cosmetic intervention, subject to the same regulatory framework as existing practice. This would assist in refocusing the political landscape by erring on the side of liberty rather than that of biology.

Keywords: biopolitics, body modification, consent, criminal law

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Authors: Amir Shariffar, Haider Salman, Tanveer Siddique, Omar Manasreh

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According to the recent studies on metal-oxide memristors, researchers tend to improve the stability, endurance, and uniformity of resistive switching (RS) behavior in memristors. Specifically, the main challenge is to prevent abrupt ruptures in the memristor’s filament during the RS process. To address this problem, we are proposing a low-cost hybrid structure of metal oxide quantum dots (QDs) and thin films to control the formation of filaments in memristors. We aim to use metal oxide quantum dots because of their unique electronic properties and quantum confinement, which may improve the resistive switching behavior. QDs have discrete energy spectra due to electron confinement in three-dimensional space. Because of Coulomb repulsion between electrons, only a few free electrons are contained in a quantum dot. This fact might guide the growth direction for the conducting filaments in the metal oxide memristor. As a result, it is expected that QDs can improve the endurance and uniformity of RS behavior in memristors. Moreover, we use a hybrid structure of intrinsic n-type quantum dots and p-type thin films to introduce a potential barrier at the junction that can smooth the transition between high and low resistance states. A bottom-up approach is used for fabricating the proposed memristor using different types of metal-oxide QDs and thin films. We synthesize QDs including, zinc oxide, molybdenum trioxide, and nickel oxide combined with spin-coated thin films of titanium dioxide, copper oxide, and hafnium dioxide. We employ fluorine-doped tin oxide (FTO) coated glass as the substrate for deposition and bottom electrode. Then, the active layer composed of one type of quantum dots, and the opposite type of thin films is spin-coated onto the FTO. Lastly, circular gold electrodes are deposited with a shadow mask by using electron-beam (e-beam) evaporation at room temperature. The fabricated devices are characterized using a probe station with a semiconductor parameter analyzer. The current-voltage (I-V) characterization is analyzed for each device to determine the conduction mechanism. We evaluate the memristor’s performance in terms of stability, endurance, and retention time to identify the optimal memristive structure. Finally, we assess the proposed hypothesis before we proceed to the optimization process for fabricating the memristor.

Keywords: memristor, quantum dot, resistive switching, thin film

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Authors: Saud Hamdan Alshammari

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Photocatalytic water splitting to produce hydrogen (H₂) has obtained significant attention as an environmentally friendly technology. This process, which produces hydrogen from water and sunlight, represents a renewable energy source. Titanium dioxide (TiO₂) plays a critical role in photocatalytic hydrogen production due to its chemical stability, availability, and low cost. Nevertheless, TiO₂'s wide band gap (3.2 eV) limits its visible light absorption and might affect the effectiveness of the photocatalytic. Coupling TiO₂ with other semiconductors is a strategy that can enhance TiO₂ by narrowing its band gap and improving visible light absorption. This paper studies the modification of TiO₂ by coupling it with another semiconductor such as CdS nanoparticles using a reflux reactor and autoclave reactor that helps form a core-shell structure. Characterization techniques, including TEM and UV-Vis spectroscopy, confirmed successful coating of TiO₂ on CdS core, reduction of the band gap from 3.28 eV to 3.1 eV, and enhanced light absorption in the visible region. These modifications are attributed to the heterojunction structure between TiO₂ and CdS.The essential goal of this study is to improve TiO₂ for use in photocatalytic water splitting to enhance hydrogen production. The core-shell TiO₂@CdS nanoparticles exhibited promising results, due to band gap narrowing and improved light absorption. Future work will involve adding Pt as a co-catalyst, which is known to increase surface reaction activity by enhancing proton adsorption. Evaluation of the TiO₂@CdS@Pt catalyst will include performance assessments and hydrogen productivity tests, considering factors such as effective shapes and material ratios. Moreover, the study could be enhanced by studying further modifications to the catalyst and displaying additional performance evaluations. For instance, doping TiO₂ with metals such as nickel (Ni), iron (Fe), and cobalt (Co) and non-metals such as nitrogen (N), carbon (C), and sulfur (S) could positively influence the catalyst by reducing the band gap, enhancing the separation of photogenerated electron-hole pairs, and increasing the surface area, respectively. Additionally, to further improve catalytic performance, examining different catalyst morphologies, such as nanorods, nanowires, and nanosheets, in hydrogen production could be highly beneficial. Optimizing photoreactor design for efficient photon delivery and illumination will further enhance the photocatalytic process. These strategies collectively aim to overcome current challenges and improve the efficiency of hydrogen production via photocatalysis.

Keywords: hydrogen production, photocatalytic, water spliiting, semiconductor, nanoparticles

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Authors: Archana Sharma, Vijayashree Nayak, Ashok Kumar

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Three-dimensional matrices were fabricated from blend of natural-natural polymers like carrageenan-gelatin and synthetic -natural polymers such as PEG- gelatin (PEG of different molecular weights (2,000 and 6,000) using two different crosslinkers; glutaraldehyde and EDC-NHS by cryogelation technique. Blends represented a feasible approach to design 3-D scaffolds with controllable mechanical, physical and biochemical properties without compromising biocompatibility and biodegradability. These matrices possessed interconnected porous structure, good mechanical strength, biodegradable nature, constant swelling kinetics, ability to withstand high temperature and visco-elastic behavior. Hemocompatibility of cryogel matrices was determined by coagulation assays and hemolytic activity assay which demonstrated that these cryogels have negligible effects on coagulation time and have excellent blood compatibility. In vitro biocompatibility (cell-matrix interaction) inferred good cell adhesion, proliferation, and secretion of ECM on matrices. These matrices provide a microenvironment for the growth, proliferation, differentiation and secretion of ECM of different cell types such as IMR-32, C2C12, Cos-7, rat bone marrow derived MSCs and human bone marrow MSCs. Hoechst 33342 and PI staining also confirmed that the cells were uniformly distributed, adhered and proliferated properly on the cryogel matrix. An ideal scaffold used for tissue engineering application should allow the cells to adhere, proliferate and maintain their functionality. Neurotransmitter analysis has been done which indicated that IMR-32 cells adhered, proliferated and secreted neurotransmitters when they interacted with these matrices which showed restoration of their functionality. The cell-matrix interaction up to molecular level was also evaluated so to check genotoxicity and protein expression profile which indicated that these cryogel matrices are non-genotoxic and maintained biofunctionality of cells growing on these matrices. All these cryogels, when implanted subcutaneously in balb/c mice, showed no adverse systemic or local toxicity effects at implantation site. There was no significant increase in inflammatory cell count has otherwise been observed after scaffold implantation. These cryogels are supermacroporous and this porous structure allows cell infiltration and proliferation of host cells. This showed the integration and presence of infiltrated cells into the cryogel implants. Histological analysis confirmed that the implanted cryogels do not have any adverse effect in spite of host immune system recognition at the site of implantation, on its surrounding tissues and other vital host organs. In vivo biocompatibility study after in vitro biocompatibility analysis has also concluded that these synthesized cryogels act as important biological substitutes, more adaptable and appropriate for transplantation. Thus, these cryogels showed their potential for soft tissue engineering applications.

Keywords: cryogelation, hemocompatibility, in vitro biocompatibility, in vivo biocompatibility, soft tissue engineering applications

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Authors: Igor V. Savchenko, Dmitrii A. Samoshkin

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The active study of the properties of lanthanides has begun in the late 50s of the last century, when methods for their purification were developed and metals with a relatively low content of impurities were obtained. Nevertheless, up to date, many properties of the rare earth metals (REM) have not been experimentally investigated, or insufficiently studied. Currently, the thermal conductivity and thermal diffusivity of lanthanides have been studied most thoroughly in the low-temperature region and at moderate temperatures (near 293 K). In the high-temperature region, corresponding to the solid phase, data on the thermophysical characteristics of the REM are fragmentary and in some cases contradictory. Analysis of the literature showed that the data on the thermal conductivity and thermal diffusivity of light REM in the liquid state are few in number, little informative (only one point corresponds to the liquid state region), contradictory (the nature of the thermal conductivity change with temperature is not reproduced), as well as the results of measurements diverge significantly beyond the limits of the total errors. Thereby our experimental results allow to fill this gap and to clarify the existing information on the heat transfer coefficients of neodymium and samarium in a wide temperature range from the melting point up to 1770 K. The measurement of the thermal conductivity of investigated metallic melts was carried out by laser flash technique on an automated experimental setup LFA-427. Neodymium sample of brand NM-1 (99.21 wt % purity) and samarium sample of brand SmM-1 (99.94 wt % purity) were cut from metal ingots and then ones were annealed in a vacuum (1 mPa) at a temperature of 1400 K for 3 hours. Measuring cells of a special design from tantalum were used for experiments. Sealing of the cell with a sample inside it was carried out by argon-arc welding in the protective atmosphere of the glovebox. The glovebox was filled with argon with purity of 99.998 vol. %; argon was additionally cleaned up by continuous running through sponge titanium heated to 900–1000 K. The general systematic error in determining the thermal conductivity of investigated metallic melts was 2–5%. The approximation dependences and the reference tables of the thermal conductivity and thermal diffusivity coefficients were developed. New reliable experimental data on the transport properties of the REM and their changes in phase transitions can serve as a scientific basis for optimizing the industrial processes of production and use of these materials, as well as ones are of interest for the theory of thermophysical properties of substances, physics of metals, liquids and phase transformations.

Keywords: high temperatures, laser flash technique, liquid state, metallic melt, rare earth metals, thermal conductivity, thermal diffusivity

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Authors: Erickson Bernardo, Caridad Pineda

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The project Adolescent Reproductive Health Information and Services (ARHIS) is a nine-month pilot project which intends to bridge the existing gap between reproductive health information and services, particularly with regard to family planning and HIV, among adolescent boys and girls aged 10-19 years in the 2nd Congressional District of Quezon City, in the Philippines. It aims to increase adolescents' and young people's awareness about their reproductive health concerns and at the same time make a wide range of reproductive health (RH) services accessible and available to them. A number of methodologies were utilized in the implementation of the project. At the onset, a baseline survey was conducted by community mobilizers to gather a situational analysis of adolescents' and young people's issues and concerns. The results of this survey were then presented in a multi-stakeholders' meeting to gather community support and foster their involvement. Further, interactive learning sessions (ILS) on a variety of reproductive health topics, among young people, parents and community leaders based on the results of the baseline survey was conducted. With regard to reproductive health service provision, both facility-based delivery and conduct of outreach activities were employed. In the span of nine months, the project was able to yield the following results: • A total of 521 adolescents and youth (AY) were reached by ILS on puberty, responsible relationships, teenage pregnancy, family planning, as well as HIV & AIDS. • A total of 218 parents and community leaders were informed of AY RH-related issues and concerns. • More than 350 AYs availed of a wide range of FP services including pills – both combined oral and progestin-only, and progestin-only injectables and implants. • More than 380 AYs availed of condoms as means of STI and HIV prevention. A noble initiative of the project is the utilization of a "condom distributor", a youth leader who has been educated about STI and HIV prevention as well as correct condom use, as the focal point for condom access in the community. • A total of 25 young people, parents, and community leaders were identified as ARHIS champions who have been instrumental in the achievement of project deliverables through their dedication and commitment to support the project. The concept of adolescent sexual and reproductive health (ASRH) remains to be a major challenge in the Philippine context. This is due to the fact that majority of Filipinos are still not keen on discussing issues and concerns related to ASRH, albeit the alarming number of teenage pregnancies and the rapid increase of HIV cases among 15- 24 year olds. In addition, Republic Act 10354 or the Responsible Parenthood and Reproductive Health Act of 2012, requires minor adolescents to present a written parental consent prior to accessing RH services. However, with the involvement and support of parents and key community stakeholders, these barriers may be addressed. The project has demonstrated how adolescents and young people yearn for reproductive health information and services.

Keywords: adolescent sexual reproductive health, barriers to access, reproductive health information and services, teenage pregnancies

Procedia PDF Downloads 177

Authors: Fatna Benmessaoud, Mohammed Cheikh, Vencent Velay, Vanessa Vidal, Farhad Rezai-Aria, Christine Boher

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Ti-6Al-4V titanium alloy is one of the most widely used materials in aeronautical and aerospace industries. Because of its high specific strength, good fatigue, and corrosion resistance, this alloy is very suitable for moderate temperature applications. At room temperature, Ti-6Al-4V mechanical behavior is generally controlled by the behavior of alpha phase (beta phase percent is less than 8%). The plastic strain of this phase notably based on crystallographic slip can be hindered by various obstacles and mechanisms (crystal lattice friction, sessile dislocations, strengthening by solute atoms and grain boundaries…). The grains aspect of alpha phase (its morphology and texture) and the nature of its crystallographic lattice (which is hexagonal compact) give to plastic strain heterogeneous, discontinuous and anisotropic characteristics at the local scale. The aim of this work is to develop a multi-scale model for Ti-6Al-4V mechanical behavior using crystal plasticity approach; this multi-scale model is used then to investigate grains size, dispersion of grains size, crystallographic texture and slip systems activation effects on Ti-6Al-4V mechanical behavior under monotone quasi-static loading. Nine representative elementary volume (REV) are built for taking into account the physical elements (grains size, dispersion and crystallographic) mentioned above, then boundary conditions of tension test are applied. Finally, simulation of the mechanical behavior of Ti-6Al-4V and study of slip systems activation in alpha phase is reported. The results show that the macroscopic mechanical behavior of Ti-6Al-4V is strongly linked to the active slip systems family (prismatic, basal or pyramidal). The crystallographic texture determines which family of slip systems can be activated; therefore it gives to the plastic strain a heterogeneous character thus an anisotropic macroscopic mechanical behavior of Ti-6Al-4V alloy modeled. The grains size influences also on mechanical proprieties of Ti-6Al-4V, especially on the yield stress; by decreasing of the grain size, the yield strength increases. Finally, the grains' distribution which characterizes the morphology aspect (homogeneous or heterogeneous) gives to the deformation fields distribution enough heterogeneity because the crystallographic slip is easier in large grains compared to small grains, which generates a localization of plastic deformation in certain areas and a concentration of stresses in others.

Keywords: multi-scale modeling, Ti-6Al-4V alloy, crystal plasticity, grains size, crystallographic texture

Procedia PDF Downloads 157

Authors: Nayeli Camacho, Fernanda Lara-Perez, Carolina Ortega-Portilla, Diego G. Espinosa-Arbelaez, Juan M. Alvarado-Orozco, Guillermo C. Mondragon-Rodriguez

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Ultra-high molecular weight polyethylene (UHMWPE) has been the gold standard material for total knee replacements for almost five decades. Wear damage to UHMWPE articulating surface is inevitable due to the natural sliding and rolling movements of the knee. This generates a considerable amount of wear debris, which results in mechanical instability of the joint, reduces joint mobility, increases pain with detrimental biologic responses, and causes component loosening. The presence of wear particles has been closely related to adverse reactions in the knee joint surrounding tissue, especially for particles in the range of 0.3 to 2 μm. Carbon-based materials possess excellent mechanical properties and have shown great promise in tribological applications. In this study, diamond-like carbon coatings (DLC) and carbon nanotubes (CNTs) were used to decrease the wear rate of ultra-high molecular weight polyethylene. A titanium doped DLC (Ti-DLC) was deposited by magnetron sputtering on stainless steel precision spheres while CNTs were used as a second phase reinforcement in UHMWPE at a concentration of 1.25 wt.%. A comparative tribological analysis of the wear of UHMWPE and UHMWPE-CNTs with a stainless steel counterpart with and without Ti-DLC coating is presented. The experimental wear testing was performed on a pin-on-disc tribometer under dry conditions, using a reciprocating movement with a load of 1 N at a frequency of 2 Hz for 100,000 and 200,000 cycles. The wear tracks were analyzed with high-resolution scanning electron microscopy to determine wear modes and observe the size and shape of the wear debris. Furthermore, profilometry was used to study the depth of the wear tracks and to map the wear of the articulating surface. The wear tracks at 100,000 and 200,000 cycles on all samples were relatively shallow, and they were in the range of average roughness. It was observed that the Ti-DLC coating decreases the mass loss in the UHMWPE and the depth of the wear track. The combination of both carbon-based materials decreased the material loss compared to the system of stainless steel and UHMWPE. Burnishing of the surface was the predominant wear mode observed with all the systems, more subtle for the systems with Ti-DLC coatings. Meanwhile, in the system composed of stainless steel-UHMWPE, the intrinsic surface roughness of the material was completely replaced by the wear tracks.

Keywords: CNT reinforcement, self-lubricating materials, Ti-DLC, UHMWPE tribological performance

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Authors: Zhuang Yiwen

Abstract:

The paper examines the challenges facing the Singapore healthcare system related to the tracking and traceability of medical devices. One of the major challenges identified is the lack of a standard coding system for medical devices, which makes it difficult to track them effectively. The paper suggests the use of the Unique Device Identifier (UDI) as a single standard for medical devices to improve tracking and reduce errors. The paper also explores the use of barcoding and image recognition to identify and document medical devices in nursing practices. In nursing practices, the use of barcodes for identifying medical devices is common. However, the information contained in these barcodes is often inconsistent, making it challenging to identify which segment contains the model identifier. Moreover, the use of barcodes may be improved with the use of UDI, but many subsidized accessories may still lack barcodes. The paper suggests that the readiness for UDI and barcode standardization requires standardized information, fields, and logic in electronic medical record (EMR), operating theatre (OT), and billing systems, as well as barcode scanners that can read various formats and selectively parse barcode segments. Nursing workflow and data flow also need to be taken into account. The paper also explores the use of image recognition, specifically the Tesseract OCR engine, to identify and document implants in public hospitals due to limitations in barcode scanning. The study found that the solution requires an implant information database and checking output against the database. The solution also requires customization of the algorithm, cropping out objects affecting text recognition, and applying adjustments. The solution requires additional resources and costs for a mobile/hardware device, which may pose space constraints and require maintenance of sterile criteria. The integration with EMR is also necessary, and the solution require changes in the user's workflow. The paper suggests that the long-term use of Systematized Nomenclature of Medicine Clinical Terms (SNOMED CT) as a supporting terminology to improve clinical documentation and data exchange in healthcare. SNOMED CT provides a standardized way of documenting and sharing clinical information with respect to procedure, patient and device documentation, which can facilitate interoperability and data exchange. In conclusion, the paper highlights the challenges facing the Singapore healthcare system related to the tracking and traceability of medical devices. The paper suggests the use of UDI and barcode standardization to improve tracking and reduce errors. It also explores the use of image recognition to identify and document medical devices in nursing practices. The paper emphasizes the importance of standardized information, fields, and logic in EMR, OT, and billing systems, as well as barcode scanners that can read various formats and selectively parse barcode segments. These recommendations could help the Singapore healthcare system to improve tracking and traceability of medical devices and ultimately enhance patient safety.

Keywords: medical device tracking, unique device identifier, barcoding and image recognition, systematized nomenclature of medicine clinical terms

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Authors: Nino Kupatadze, Mzevinar Bedinashvili, Tamar Memanishvili, Manana Gurielidze, David Tugushi, Ramaz Katsarava

Abstract:

Bacteria easily colonize the surfaces of tissues, surgical devices (implants, orthopedics, catheters, etc.), and instruments causing surgical device related infections. Therefore, the battle against bacteria and the prevention of surgical devices from biofilm formation is one of the main challenges of biomedicine today. Our strategy to the solution of this problem consists in using antimicrobial polymeric coatings as effective “shields” to protect surfaces from bacteria’s colonization and biofilm formation. As one of the most promising approaches look be the use of antimicrobial bioerodible polymeric nanocomposites containing silver nanoparticles (AgNPs). We assume that the combination of an erodible polymer with a strong bactericide should put obstacles to bacteria to occupy the surface and to form biofilm. It has to be noted that this kind of nanocomposites are also promising as wound dressing materials to treat infected superficial wounds. Various synthetic and natural polymers were used for creating biocomposites containing AgNPs as both particles' stabilizers and matrices forming elastic films at surfaces. One of the most effective systems to fabricate AgNPs is an ethanol solution of polyvinylpyrrolidone(PVP) with dissolved AgNO3–ethanol serves as a AgNO3 reductant and PVP as AgNPs stabilizer (through the interaction of nanoparticles with nitrogen atom of the amide group). Though PVP is biocompatible and film-forming polymer, it is not a good candidate to design either "biofilm shield" or wound dressing material because of a high solubility in water – though the solubility of PVP provides the desirable release of AgNPs from the matrix, but the coating is easily washable away from the surfaces. More promising as matrices look water insoluble but bioerodible polymers that can provide the release of AgNPs and form long-lasting coatings at the surfaces. For creating bioerodible water-insoluble antimicrobial coatings containing AgNPs, we selected amino acid based biodegradable polymers(AABBPs)–poly(ester amide)s, poly(ester urea)s, their copolymers containing amide and related groups capable to stabilize AgNPs. Among a huge variety of AABBPs reported we selected the polymers soluble in ethanol. For preparing AgNPs containing nanocompositions AABBPs and AgNO3 were dissolved in ethanol and subjected to photochemical reduction using daylight-irradiation. The formation of AgNPs was observed visually by coloring the solutions in brownish-red. The obtained AgNPs were characterized by UV-spectroscopy, transmission electron microscopy(TEM), and dynamic light scattering(DLS). According to the UV and TEM data, the photochemical reduction resulted presumably in spherical AgNPs with rather high contribution of the particles below 10 nm that are known as responsible for the antimicrobial activity. DLS study showed that average size of nanoparticles formed after photo-reduction in ethanol solution ranged within 50 nm. The in vitro antimicrobial activity study of the new nanocomposite material is in progress now.

Keywords: nanocomposites, silver nanoparticles, polymer, biodegradable

Procedia PDF Downloads 396

Authors: Nidhi Sharotri, Dhiraj Sud

Abstract:

Water pollution by pesticides constitutes a serious ecological problem due to their potential toxicity and bioaccumulation. The widespread use of pesticides in industry and agriculture along with their resistance to natural decomposition, biodegradation, chemical and photochemical degradation under typical environmental conditions has resulted in the emergence of these chemicals and their transformed products in natural water. Among AOP’s, heterogeneous photocatalysis using TiO2 as photocatalyst appears as the most emerging destructive technology for mineralization of the pollutant in aquatic streams. Among the various semiconductors (TiO2, ZnO, CdS, FeTiO3, MnTiO3, SrTiO2 and SnO2), TiO2 has proven to be the most efficient photocatalyst for environmental applications due to its biological and chemical inertness, high photo reactivity, non-toxicity, and photo stability. Semiconductor photocatalysts are characterized by an electronic band structure in which valence band and conduction band are separated by a band gap, i.e. a region of forbidden energy. Semiconductor based photocatalysts produces e-/h+ pairs which have been employed for degradation of organic pollutants. The present paper focuses on modification of TiO2 photocatalyst in order to shift its absorption edge towards longer wavelength to make it active under natural light. Semiconductor TiO2 photocatalysts was prepared by doping with anion (N), cation (Mn) and double doped (Mn, N) using greener approach. Titanium isopropoxide is used as titania precursor and ethanedithiol, hydroxyl amine hydrochloride, manganous chloride as sulphur, nitrogen and manganese precursors respectively. Synthesized doped TiO2 nanomaterials are characterized for surface morphology (SEM, TEM), crystallinity (XRD) and optical properties (absorption spectra and band gap). EPR data confirms the substitutional incorporation of Mn2+ in TiO2 lattice. The doping influences the phase transformation of rutile and anatase phase crystal and thereby the absorption spectrum changes were observed. The effect of variation of reaction parameters such as solvent, reaction time and calcination temperature on the yield, surface morphology and optical properties was also investigated. The TEM studies show the particle size of nanomaterials varies from 10-50 nm. The calculated band gap of nanomaterials varies from 2.30-2.60 eV. The photocatalytic degradation of organic pollutant organophosphate pesticide (Quinalphos) has been investigated by studying the changes in UV absorption spectrum and the promising results were obtained under visible light. The complete mineralization of quinalphos has occurred as no intermediates were recorded after 8 hrs of degradation confirmed from the HPLC studies.

Keywords: quinalphos, doped-TiO2, mineralization, EPR

Procedia PDF Downloads 328