Search results for: gas barrier properties

Authors: Ali Ashjaran

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Graphene is undoubtedly emerging as one of the most promising materials because of its unique combination of superb properties, which opens a way for its exploitation in a wide spectrum of applications ranging from electronics to optics, sensors, and biodevices. In addition, Graphene-based nanomaterials have many promising applications in energy-related areas. Graphene a single layer of carbon atoms, combines several exceptional properties, which makes it uniquely suited as a coating material: transparency, excellent mechanical stability, low chemical reactivity, Optical, impermeability to most gases, flexibility, and very high thermal and electrical conductivity. Graphene is a material that can be utilized in numerous disciplines including, but not limited to: bioengineering, composite materials, energy technology and nanotechnology, biological engineering, optical electronics, ultrafiltration, photovoltaic cells. This review aims to provide an overiew of graphene structure, properties and some applications.

Keywords: graphene, carbon, anti corrosion, optical and electrical properties, sensors

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Authors: Michelle Blewitt, Scott P. Wilson, Heidi Tait, Juniper Riordan

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Rubber crumb is a physical and chemical pollutant of concern for the environment and human health, warranting immediate investigations into its pathways to the environment and potential impacts. This emerging microplastic is created by shredding end-of-life tyres into ‘rubber crumb’ particles between 1-5mm used on synthetic turf fields and soft-fall playgrounds as a solution to intensifying tyre waste worldwide. Despite having known toxic and carcinogenic properties, studies into the transportation pathways and movement patterns of rubber crumbs from these surfaces remain in their infancy. To address this deficit, AUSMAP, the Australian Microplastic Assessment Project, in partnership with the Tangaroa Blue Foundation, conducted a study to quantify crumb loss from soft-fall surfaces. To our best knowledge, this is the first of its kind, with funding for the audits being provided by the Australian Government’s Reef Trust. Sampling occurred at 12 soft-fall playgrounds within the Great Barrier Reef Catchment Area on Australia’s North-East coast, in close proximity to the United Nations World Heritage Listed Reef. Samples were collected over a 12-month period using randomized sediment cores at 0, 2 and 4 meters away from the playground edge along a 20-meter transect. This approach facilitated two objectives pertaining to particle movement: to establish that crumb loss is occurring and that it decreases with distance from the soft-fall surface. Rubber crumb abundance was expressed as a total value and used to determine an expected average of rubber crumb loss per m2. An Analysis of Variance (ANOVA) was used to compare the differences in crumb abundance at each interval from the playground. Site characteristics, including surrounding sediment type, playground age, degree of ultra-violet exposure and amount of foot traffic, were additionally recorded for the comparison. Preliminary findings indicate that crumb is being lost at considerable rates from soft-fall playgrounds in the region, emphasizing an urgent need to further examine it as a potential source of aquatic pollution, soil contamination and threat to individuals who regularly utilize these surfaces. Additional implications for the future of rubber crumbs as a fit-for-purpose recycling initiative will be discussed with regard to industry, governments and the economic burden of surface maintenance and/ or replacement.

Keywords: microplastics, toxic rubber crumb, litter pathways, marine environment

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Authors: Bilal Ahmad Ashwar, Asima Shah, S. A. Rather, Asir Gani, S.M. Wani, I.D. Wani, F. A. Masoodi, Adil Gani

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Starches isolated from two newly released rice varieties (K-322 & K-448) were subject to irradiation at 0, 5, 10, and 20 kGy doses. Comparative study between native (not irradiated) and irradiated starch samples was carried out to evaluate the changes in physicochemical, morphological and pasting properties due to gamma irradiation. Significant decrease was found in apparent amylose content, pH, swelling power, syneresis, and pasting properties, whereas carboxyl content, water absorption capacity, transmittance and solubility were found to increase with the increase in irradiation dose. Granule morphology of native and irradiated starches under scanning electron microscope revealed that granules were polygonal or irregular in shape. The starch granules were somewhat deformed by gamma irradiation. X-ray diffraction pattern showed A type of pattern in native as well as irradiated starches.

Keywords: rice starch, gamma irradiation, morphological properties, pasting properties, physicochemical properties.

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Authors: Mustafa Öztas, Metin Bedir, Yahya Özdemir

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Boron doped of In2O3 films were prepared by spray pyrolysis technique at 350 °C substrate temperature, which is a low cost and large area technique to be well-suited for the manufacture of solar cells, using boric acid (H3BO3) as dopant source, and their properties were investigated as a function of doping concentration. X-ray analysis showed that the films were polycrystalline fitting well with a hexagonal structure and have preferred orientation in (220) direction. The changes observed in the energy band gap and structural properties of the films related to the boric acid concentration are discussed in detail.

Keywords: spray pyrolysis, In2O3, boron, optical properties, boric acid

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Authors: Nassima Sotehi

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This article presents experimental and numerical results concerning the thermal properties of the porous materials used as heat insulator in the buildings sector. Initially, the thermal conductivity of three types of studied walls (classic concrete, concrete with cork aggregate and polystyrene concrete) was measured in experiments by the method of the boxes. Then a numerical modeling of the heat and mass transfers which occur within porous materials was applied to these walls. This work shows the influence of the presence of water in building materials on their thermophysical properties, as well as influence of the nature of materials and dosage of fibers introduced within these materials on the thermal and mass transfers.

Keywords: modeling, porous media, thermal materials, thermal properties

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Authors: Shanna Su, Kathleen Vincent

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Introduction: A non-hormonal prescription vaginal pH modulator (VPM) gel (Phexxi®), with active ingredients lactic acid, citric acid, and potassium bitartrate, has recently been approved for the prevention of pregnancy in the United States. The objective of this review is to compile the evidence available from published preclinical and clinical trials to support its use. Areas covered: PubMed was searched for published literature on VPM gel. Two Phase III trials were found on the clinicaltrials.gov database. The results demonstrated that VPM gel is safe, with minimal side effects, and effective (cumulative 6-7 cycle pregnancy rate of 4.1-13.65%, (Pearl Index 27.5) as a contraceptive. Microbicidal effects suggest the potential for the prevention of sexually transmitted infections (STIs); currently, a Phase III clinical trial is being conducted to evaluate the prevention of chlamydia and gonorrhea. Expert opinion: Non-hormonal reversible contraceptive options have been limited to the highly effective copper-releasing intrauterine device that requires insertion by a trained clinician and less effective coitally-associated barrier and spermicide options which are typically available over-the-counter. Spermicides, which improve the efficacy of barrier devices, may increase the risk of Human Immunodeficiency Virus (HIV)/STIs. VPM gel provides a new safe, effective non-hormonal contraceptive option with the potential for prevention of STIs.

Keywords: citric acid, lactic acid, non-hormonal contraception, potassium bitartrate, topical vaginal contraceptive, vaginal pH modulator gel

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Authors: Moez Selmi, Mariem Kacem, Mehrez Jamei, Philippe Dubujet

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Earth pressure balance (EPB) tunnel boring machines are designed for digging in different types of soil, especially clay soils. This operation requires the treatment of soil by lubricants to facilitate the procedure of excavation. A possible use of this soil is limited by the effect of treatment on the hydro-mechanical properties of the soil. This work aims to study the effect of a foaming agent on the hydro-mechanical properties of clay soil. The injection of the foam agent in the soil leads to create a soil matrix in which they are incorporated gas bubbles. The state of the foam in the soil is scalable thanks to the degradation of the gas bubbles in the soil.

Keywords: EPB, clay soils, foam agent, hydro-mechanical properties, degradation

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Authors: N. Demirsoy, N. Uçar, A. Önen, N. Kızıldağ, Ö. F. Vurur, O. Eren, İ. Karacan

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Polymer composite nano-fibers including (1, 3 wt %) silver nano-particles have been produced by electrospinning method. Polyacrylonitrile/N,N-dimethylformamide (PAN/DMF) solution has been prepared and the amount of silver nitrate has been adjusted to PAN weight. Silver nano-particles were obtained from reduction of silver ions into silver nano-particles by chemical reduction by hydrazine hydroxide (N2H5OH). The different amount of silver salt was loaded into polymer matrix to obtain polyacrylonitrile composite nano-fiber containing silver nano-particles. The effect of the amount of silver nano-particles on the properties of composite nano-fiber web was investigated. Electrical conductivity, mechanical properties, thermal properties were examined by Microtest LCR Meter 6370 (0.01 mΩ-100 MΩ), tensile tester, differential scanning calorimeter DSC (Q10) and SEM, respectively. Also, antimicrobial efficiency test (ASTM E2149-10) was done against Staphylococcus aureus bacteria. It has been seen that breaking strength, conductivity, antimicrobial effect, enthalpy during cyclization increase by use of silver nano-particles while the diameter of nano-fiber decreases.

Keywords: composite polyacrylonitrile nanofiber, electrical conductivity, electrospinning, mechanical properties, thermal properties, silver nanoparticles

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Authors: M. Al Azri, M. Elzain, K. Bouziane, S. M. Chérif

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n-Type 6H-SiC(0001) substrates were implanted with three fluencies of Mn+ 5x1015 Mn/cm2 (Mn content: 0.7%), 1x1016 (~2 %), and 5x1016 cm–2 (7%) with implantation energy of 80 keV and substrate temperature of 365ºC. The samples were characterized using Rutherford Backscattering and Channeling Spectroscopy (RBS/C), High-Resolution X-Ray Diffraction technique (HRXRD), micro-Raman Spectroscopy (μRS), and Superconducting Quantum Interference Device (SQUID) techniques. The aim of our work is to investigate implantation induced defects with dose and to study any correlation between disorder-composition and magnetic properties. In addition, ab-initio calculations were used to investigate the structural and magnetic properties of Mn-doped 6H-SiC. Various configurations of Mn sites and vacancy types were considered. The calculations showed that a substitutional Mn atom at Si site possesses larger magnetic moment than Mn atom at C site. A model is introduced to explain the dependence of the magnetic structure on site occupation. The magnetic properties of ferromagnetically (FM) and antiferromagnetically (AFM) coupled pairs of Mn atoms with and without neighboring vacancies have also been explored.

Keywords: ab-initio calculations, diluted magnetic semiconductors, magnetic properties, silicon carbide

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Authors: Adel Belayadi, Ahmed Mougari, Boualem Bourahla

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Molecular junctions are currently considered a promising style in the miniaturization of electronic devices. In this contribution, we provide a tight-binding model to investigate the quantum transport properties across-molecular junctions sandwiched between 2D-graphene nanoribbons in the zigzag direction. We investigate, in particular, the effect of embedded atoms such as Gold and Silicon across the molecular junction. The results exhibit a resonance behavior in terms of incident Fermi levels, depending on the molecular junction type. Additionally, the transport properties under a perpendicular magnetic field exhibit an oscillation for the transmittance versus the magnetic field strength.

Keywords: molecular junction, 2D-graphene nanoribbons, quantum transport properties, magnetic field

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Authors: Ravi Prasad Darapureddi

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The use of industrial waste in making concrete reduce the consumption of natural resources and pollution of the environment. These materials possess problems of disposal and health hazards. An attempt has been made to use paper and thermal industrial wastes such as lime sludge and flyash. Present investigation is aimed at the utilization of Lime Sludge and Flyash as Supplementary Cementitious Materials (SCM) and influence of these materials on strength properties of concrete. Thermal industry waste fly ash is mixed with lime sludge and used as a replacement to cement at different proportions to obtain the strength properties and compared with ordinary concrete prepared without any additives. Grade of concrete prepared was M₂₅ designed according to Indian standard method. Cement has been replaced by paper industry waste and fly ash in different proportions such as 0% (normal concrete), 10%, 20%, and 30% by weight. Mechanical properties such as compressive strength, splitting tensile strength and flexural strength were assessed. Test results indicated that the use of lime sludge and Fly ash in concrete had improved the properties of concrete. Better results were observed at 20% replacement of cement with these additives.

Keywords: supplementary cementitious materials, lime sludge, fly ash, strength properties

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Authors: Venkatesan Sundaramoorthy

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The field of ceramics has undergone a remarkable transformation with the advent of additive manufacturing technologies. This comprehensive review explores the mechanical properties of additively manufactured ceramic components, focusing on key materials such as Alumina, Zirconia, and Silicon Carbide. The study delves into various authors' review technology into the various additive manufacturing techniques, including Stereolithography, Powder Bed Fusion, and Binder Jetting, highlighting their advantages and challenges. It provides a detailed analysis of the mechanical properties of these ceramics, offering insights into their hardness, strength, fracture toughness, and thermal conductivity. Factors affecting mechanical properties, such as microstructure and post-processing, are thoroughly examined. Recent advancements and future directions in 3D-printed ceramics are discussed, showcasing the potential for further optimization and innovation. This review underscores the profound implications of additive manufacturing for ceramics in industries such as aerospace, healthcare, and electronics, ushering in a new era of engineering and design possibilities for ceramic components.

Keywords: mechanical properties, additive manufacturing, ceramic materials, PBF

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Authors: Hossein Alimohammadi, Mohsen Amirmojahedi, Mehrdad Rowhani

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Soil properties are used by geotechnical engineers to evaluate and analyze site conditions for designing purposes. Although basic soil classification tests are easy to perform and provide useful information to determine the properties of soils, it may take time to get the result and add some costs to the projects. Standard Penetration Test (SPT) provides an opportunity to evaluate soil parameters without performing laboratory tests. In addition to its simplicity and cheapness, the results become available immediately. This research provides a guideline on the application of the SPT test method, reliability of adapting the SPT test results in evaluating soil physical and mechanical properties such as Atterberg limits, shear strength, and compressive strength compressibility parameters. A total of 70 boreholes were investigated in this study by taking soil samples between depths of 1.2 to 15.25 meters. The project site was located in Morrow County, Ohio. A regression-based formula was proposed based on Tobit regression with a stepwise variable selection analysis conducted between SPT and other typical soil properties obtained from soil tests. The results of the research illustrated that the shear strength and physical properties of the soil affect the SPT number. The proposed correlation can help engineers to use SPT test results in their design with higher accuracy.

Keywords: standard penetration test, soil properties, soil classification, regression method

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Authors: Mahfuzur Rahman

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Back-contact solar cells improve optical properties by moving all electrically conducting parts to the back of the cell. The cell's structure allows silicon solar cells to surpass the 25% efficiency barrier and interdigitated solar cells are now the most efficient. In this work, the fabrication of a light, efficient and temperature resistant interdigitated back contact (IBC) solar cell is investigated. This form of solar cell differs from a conventional solar cell in that the electrodes are located at the back of the cell, eliminating the need for grids on the top, allowing the full surface area of the cell to receive sunlight, resulting in increased efficiency. In this project, we will use SILVACO TCAD, an optoelectronic device simulator, to construct a very thin solar cell with dimensions of 100x250um in 2D Luminous. The influence of sunlight intensity and atmospheric temperature on solar cell output power is highly essential and it has been explored in this work. The cell's optimum performance with 150um bulk thickness provides 28.81% efficiency with an 87.68% fill factor rate making it very thin, flexible and resilient, providing diverse operational capabilities.

Keywords: interdigitated, shading, recombination loss, incident-plane, drift-diffusion, luminous, SILVACO

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Authors: Awadhesh Kishore, Tushar Sharma

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The goal of this study was to compare the free radical-scavenging (FRS) characteristics of four Indian moringa (Moringa oleifera) plant components: flowers, tender and mature leaves, and seeds that were collected from three Indian districts: Jaipur, Dehra Dun, and Gwalior; in every month of 2021–2022. The samples were collected from three randomly selected agroforest locations from each district. The samples were extracted, and antioxidant properties were determined following the DPPH method with minor modifications. The FRS properties were calculated as the non-absorbance values of the sample in percentage. The factorial ANOVA statistical analysis technique was implemented for comparing FRS properties, and an MS Office Excel 2016 analysis pack was used to compare data. The flowers from Dehra Dun had superior FRS properties (27.06±1.03%), while the seeds from the same location were inferior (8.64±0.17%). The FRS properties of flowers (26.27±0.61%) were not statistically different (P > 0.05) compared to those of tender (27.30±0.63%) and mature leaves (28.37±0.59%), but significantly higher (P < 0.05) than those of seeds (9.31±0.16%). However, the FRS properties in Indian moringa were significantly higher during the winter (Jan 28.67±1.48%) compared to that in the summer (Jun 14.03±0.79%) season, but collected from three locations, viz. Gwalior (22.35±0.70%), Jaipur (23.06±0.73%), and Dehra Dun (23.10±0.76%), were not significantly different (P > 0.05). Based on this study, it can be concluded that the FRS value of flowers during the winter season is superior.

Keywords: flowers, free radical-scavenging, leaves, moringa oleifera, seeds

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Authors: Temitope Olumide Olugbade

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Low resistance and delayed fracture to corrosion, especially in harsh environmental conditions, often limit the wide application of high-manganese (high-Mn) steels. To address this issue, the present work investigates the influence of microalloying on the corrosion properties of high-Mn steels. Microalloyed and base high-Mn steels were synthesized through an arc melting process under an argon atmosphere. To generate different microstructures, the temperature and duration were varied via thermal homogenization treatments. The electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques were used to determine the corrosion properties in 0.6 M NaCl aqueous solution at room temperature. The relationship between the microstructures and corrosion properties was investigated via Scanning Kelvin Probe Microscopy (SKPFM), energy dispersive X-ray spectroscopy (EDX), and Scanning electron microscopy (SEM) techniques. The local corrosion properties were investigated via in situ atomic force spectroscopy (AFM), considering the homogenization treatments. The results indicate that microalloying is a successful technique for enhancing the corrosion behavior of high-Mn steels. Compared to other alloying elements, Vanadium has shown improvement in corrosion properties for both general and local corrosion in chloride environments.

Keywords: corrosion, high-manganese steel, homogenization, microalloying, vanadium

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Authors: I. Benkaddour, Y. Benkaddour, A. Benk Addour

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The structural, elastic, Thermal, electronic, and magnetic properties of intermetallic RMn₂Ge₂ (R= Ca, Y, Nd) are investigated by density functional theory (DFT), using the full potential –linearised augmented plane wave method (FP-LAPW). In this approach, the local-density approximation (LDA) is used for the exchange-correlation (XC) potential. The equilibrium lattice constant and magnetic moment agree well with the experiment. The density of states shows that these phases are conductors, with contribution predominantly from the R and Mn d states. We have determined the elastic constants C₁₁, C₁₂, C₁₃, C₄₄, C₃₃, andC₆₆ at ambient conditions in, which have not been established neither experimentally nor theoretically. Thermal properties, including the relative expansion coefficients and the heat capacity, have been estimated using a quasi-harmonic Debye model.

Keywords: RMn₂Ge₂, intermetallic, first-principles, density of states, mechanical properties

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Authors: Alaeddine Kaouka

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The properties and characterization of Ti-6Al-4V alloys with different contents of Mo were investigated. Microstructure characterization and hardness are considered. The alloy structure was characterized by X-ray diffraction, SEM and optical microscopy. The results showed that the addition of Mo stabilized the β-phase in the treated solution condition. The Mo element added to titanium alloys changes the lattice parameters of phases. Microstructural observations indicate an obvious reduction in the prior grain size. The hardness has increased with the increase in β-phase stability, while Young’s modulus and ductility have decreased.

Keywords: characterization, mechanical properties, molybdenum, titanium alloy

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Authors: Slim Souissi, Mohamed Ben Amar, Nesrine Bouhamed, Pierre Marechal

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The bio-composites development from biodegradable materials and natural fibers has a growing interest in the science of composite materials. The present work was conducted as part of a cooperation project between the Sfax University and the Havre University. This work consists in developing and monitoring the properties of a composite material of olive flour wood with a polymer matrix (urea formaldehyde). For this, ultrasonic non-destructive and destructive methods of characterization were used to optimize the mechanical and acoustic properties of the studied material based on the elaboration parameters.

Keywords: bio-composite, olive flour wood, polymer matrix, ultrasonic methods, mechanical properties

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Authors: Adebola Ajayi, Olakunle M. Makanjuola

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Effect of sprouting period on proximate, functional and mineral properties of malted sorghum flour was evaluated. The study was carried out to determine the proximate, functional and mineral properties of sprouting period on malted sorghum flour produced. The malted sorghum flour was obtained by sorting, weighing, washing, steeping, draining, germination, drying, dry milling, sieving. Malted sorghum flour was evaluated for proximate composition, functional properties and mineral contents. Moisture, protein, fat content, crude fiber, ash contents and carbohydrate of 24 and 48 hours, were in the range of 10.50-11.0, 11.17-11.17, 1.50-4.00, 2.50-1.50, 1.50-1.54 and 73.15-70.79% respectively. Bulk density ranged between 0.64 and 0.59g/ml, water and oil absorption capacities ranged between 139.3 and 150.0 and 217.3 and 222.7g/g respectively. Calcium, Magnesium, Zinc, Iron and Manganese were also range of 12.5, 59.3-60.0, 3.22-3.25, 3.80-3.90 and 3.22-3.25 mg/100g respectively. The results indicate that the germination of red sorghum resulted in the enhancement of the nutritional quality and its functional properties.

Keywords: sprouting, sorghum, malted sorghum flour, cabinet dryer

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Authors: Dawit Hoyiso, Abinet Arega, Terefe Markos

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Background: - In spite of all the various programs and strategies to promote the use of research finding there is still gap between theory and practice. Difference in outcomes, health inequalities, and poorly performing health service continue to present a challenge to all nurses. A number of studies from various countries have reported that nurses’ experience of evidence-based practice is low. In Ethiopia there is an information gap on the extent of evidence based nursing practice and its associated factors. Objective: - the study aims to assess the implementation of evidence based nursing practice and associated factors among nurses in Jimma zone public hospitals. Method: - Institution based cross-sectional study was conducted from March 1-30/2015. A total of 333 sampled nurses for quantitative and 8 in-depth interview of key informants were involved in the study. Semi-structured questionnaire was adapted from funk’s BARRIER scale and Friedman’s test. Multivariable Linear regression was used to determine significance of association between dependent and independent variables. Pretest was done on 17 nurses of Bedele hospital. Ethical issue was secured. Result:-Of 333 distributed questionnaires 302 were completed, giving 90.6% response rate. Of 302 participants 245 were involved in EBP activities to different level (from seldom to often). About forty five(18.4%) of the respondents had implemented evidence based practice to low level (sometimes), one hundred three (42 %) of respondents had implemented evidence based practice to medium level and ninety seven (39.6 %) of respondents had implemented evidence based practice to high level(often). The first greatest perceived barrier was setting characteristic (mean score=26.60±7.08). Knowledge about research evidence was positively associated with implementation of evidence based nursing practice (β=0.76, P=0.008). Similarly, Place where the respondent graduated was positively associated with implementation of evidence based nursing practice (β=2.270, P=0.047). Also availability of information resources was positively associated with implementation of evidence based practice (β=0.67, P= 0.006). Conclusion: -Even though larger portion of nurses in this study were involved in evidence-based practice whereas small number of participants had implemented frequently. Evidence-based nursing practice was positively associated with knowledge of research, place where respondents graduated, and the availability of information resources. Organizational factors were found to be the greatest perceived barrier. Intervention programs on awareness creation, training, resource provision, and curriculum issues to improve implementation of evidence based nursing practice by stakeholders are recommended.

Keywords: evidence based practice, nursing practice, research utilization, Ethiopia

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Authors: Maruf Yinka Kolawole, Jacob Olayiwola Aweda, Farasat Iqbal, Asif Ali, Sulaiman Abdulkareem

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Zinc is a non-ferrous metal with potential application in orthopaedic implant materials. However, its poor mechanical properties were major challenge to its application. Therefore, this paper studies the mechanical properties of biodegradable Zn-based alloy for biomedical application. Pure zinc powder with varying (0, 1, 2, 3 & 6) wt% of magnesium powders were ball milled using ball-to-powder ratio (B:P) of 10:1 at 350 rpm for 4 hours. The resulting milled powders were compacted and sintered at 300 MPa and 350 °C respectively. Microstructural, phase and mechanical properties analyses were performed following American standard of testing and measurement. The results show that magnesium has influence on the mechanical properties of zinc. The compressive strength, hardness and elastic modulus of 210 ± 8.878 MPa, 76 ± 5.707 HV and 45 ± 11.616 GPa respectively as obtained in Zn-2Mg alloy were optimum and meet the minimum requirement of biodegradable metal for orthopaedics application. These results indicate an increase of 111, 93 and 93% in compressive strength, hardness and elastic modulus respectively as compared to pure zinc. The increase in mechanical properties was adduced to effectiveness of compaction pressure and intermetallic phase formation within the matrix resulting in high dislocation density for improving strength. The study concluded that, Zn-2Mg alloy with optimum mechanical properties can therefore be considered a potential candidate for orthopaedic application.

Keywords: Biodegradable metal, Biomedical application, Mechanical properties, Powder Metallurgy, Zinc

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Authors: Sukhdeep Singh Gill, Gurbhinder Singh Brar

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In recent years, friction stir welding (FSW) has attracted the main attention of the concerned researcher especially in case of joining of nonferrous alloys like aluminum and magnesium due to its unmatchable properties with respect to other welding techniques. Friction stir welding is a solid state welding process which is most suitable for the welding of nonferrous alloys, especially aluminum and magnesium alloys. Aluminum and magnesium alloys are widely used for structural applications of all types of automobiles due to their superior mechanical properties with their low density. This paper deals with the critical review of the different properties (like tensile strength, microhardness, impact strength, corrosion resistance, and metallurgical investigation on SEM) obtained by the FSW of aluminum and magnesium alloys. After a critical review of the existing published literature on concerned topics, all the properties of welding joins are compared in the tabulated manner to optimize the selection of materials and FSW parameters according to mechanical and tribological properties. Different tool designs used for the FSW process are also thoroughly studied, and the influence of the design of the tool used in FSW on the different properties has also been incorporated in this paper. It has been observed from the existing published literature that FSW is the most effective and practical technique for joining the non ferrous alloys especially aluminum and magnesium alloys, and among the different FSW tools, left hand threaded tri-flute (LHTTF) tool is best for the welding of non ferrous alloys like aluminum and magnesium alloys which gives the superior mechanical properties to welding joint.

Keywords: aluminum, friction stir welding, magnesium, structural applications, tool design

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Authors: Farah Marsusi, Mohammad Qasemnazhand

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Density-functional theory (DFT) was applied to investigate the geometry and electronic properties H-terminated Si-fullerene (Si-fullerane). Natural bond orbital (NBO) analysis confirms sp3 hybridization nature of Si-Si bonds in Si-fulleranes. Quantum confinement effect (QCE) does not affect band gap (BG) so strongly in the size between 1 to 1.7 nm. In contrast, the geometry and symmetry of the cage have significant influence on BG. In contrast to their carbon analogues, pentagon rings increase the stability of the cages. Functionalized Si-cages are stable and can be chemically very active. The electronic properties are highly sensitive to the surface chemistry via functionalization with different chemical groups. As a result, BGs and chemical activities of these cages can be drastically tuned through the chemistry of the surface.

Keywords: density functional theory, sila-fullerens, NBO analysis, opto-electronic properties

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Authors: Nour Hassan Ismail, Abdelmonem Nassar, Khaled Baz

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Semiconductor crystals smaller than about 10 nm, known as quantum dots, have properties that differ from large samples, including a band gap that becomes larger for smaller particles. These properties create several applications for quantum dots. In this paper, new shapes of quantum dot arrays are used to enhance the photo physical properties of gold nano-particles. This paper presents a study of the effect of nano-particles shape, array, and size on their absorption characteristics.

Keywords: quantum dots, nano-particles, LSPR

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Authors: Anil Nis, Nilufer Ozyurt Zihnioglu

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The object of the study is to investigate fresh state properties of the steel fiber reinforced self-compacting concrete (SFR-SCC). Three different steel fibers; straight (Vf:0.5%), hooked-end long (Vf:0.5% and 1%) and hybrid fibers (0.5%short+0.5%long) were used in the research aiming to obtain flow properties of non-fibrous self-compacting concrete. Fly ash was used as a supplementary with an optimum dosage of 30% of the total cementitious materials. Polycarboxylic ether based high-performance concrete superplasticizer was used to get high flowability with percentages ranging from 0.81% (non-fibrous SCC) to 1.07% (hybrid SF-SCC) of the cement weight. The flowability properties of SCCs were measured via slump flow and V-funnel tests; passing ability properties of SCCs were measured with J-Ring, L-Box, and U-Box tests. Workability results indicate that small increase on the superplasticizer dosages compensate the adverse effects of steel fibers on flowability properties of SSC. However, higher dosage fiber addition has a negative effect on passing ability properties, causing blocking of the mixes. In addition, compressive strength, tensile strength, and four point bending results were given. Results indicate that SCCs including steel fibers have superior performances on tensile and bending strength of concrete. Crack bridging capability of steel fibers prevents concrete from splitting, yields higher deformation and energy absorption capacities than non-fibrous SCCs.

Keywords: fiber reinforced self-compacting concrete, fly ash, fresh state properties, steel fiber

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Authors: Dolly Selikane, Thandi Gumede

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Among the commonly studied organic fillers for polycaprolactone (PCL), cellulose is the most promising. It is available in various particle sizes and sources, providing numerous options for finding a suitable match for PCL matrices. In this study, cellulose was extracted from the leaves of E. autumnalis to create a PCL/nanocellulose composite through melt blending. The prepared nanocellulose was blended with PCL at a weight ratio of 97/3, and the resulting composite was characterized by its thermal and mechanical properties. The results showed that the addition of nanocellulose to PCL improved its mechanical properties, with a maximum increase of 29% in tensile strength and 31% in Young's modulus. The SEM analysis confirmed the successful blending of PCL and nanocellulose. The findings of this study suggest that the nanocellulose from Eucomis autumnalis plant has the potential to improve the mechanical properties of PCL and could be used in biomedical and packaging applications.

Keywords: polycaprolactone, medicinal plants, Eucomis autumnalis, nanocellulose, composite

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Authors: Chaomeng Liu, Li Li, Xiao Wang, Li Ren, Qinge Zhang

Abstract:

Late-life depression (LLD) is a prevalent mental disorder among the elderly, frequently accompanied by significant cognitive decline, and has emerged as a worldwide public health concern. Microglia, astrocytes, and peripheral immune cells play pivotal roles in regulating inflammatory responses within the central nervous system (CNS) across diverse cerebral disorders. This review commences with the clinical research findings and accentuates the recent advancements pertaining to microglia and astrocytes in the neuroinflammation process of LLD. The reciprocal communication network between the CNS and immune system is of paramount importance in the pathogenesis of depression and cognitive decline. Stress-induced downregulation of tight and gap junction proteins in the brain results in increased blood-brain barrier permeability and impaired astrocyte function. Concurrently, activated microglia release inflammatory mediators, initiating the kynurenine metabolic pathway and exacerbating the quinolinic acid/kynurenic acid imbalance. Moreover, the balance between Th17 and Treg cells is implicated in the preservation of immune homeostasis within the cerebral milieu of individuals suffering from LLD. The ultimate objective of this review is to present future strategies for the management and treatment of LLD, informed by the most recent advancements in research, with the aim of averting or postponing the onset of AD.

Keywords: neuroinflammation, late-life depression, microglia, astrocytes, central nervous system, blood-brain barrier, Kynurenine pathway

Procedia PDF Downloads 22

Authors: Shahid Iqbal, Haroon Z. Khan, Muhammad Arif

Abstract:

A sustainable agricultural system involving the improvement in soil properties and crop performance cannot be developed without organic fertilizer use. The effects of poultry manure compost (PMC) and pressmud compost (PrMC) at different levels on improving the soil properties and maize performance has not been yet described by any study comprehensively. Thus, field experiments (2011 and 2012) were conducted at Agronomy Research Area, University of Agriculture Faisalabad (31°26'5" N and 73°4'6" E) in sandy loam soil to determine the improvement in soil properties and maize performance due to application of PMC and PrMC each at five different levels (2, 4, 6, 8 and 10 t ha-1). A control (unamended) treatment was also included for comparison. The results indicated that performance of PMC levels was superior to PrMC levels. Increasing both composts levels improved soil properties, maize growth, and stover yield. Results showed that during both years’ highest rates of PMC i.e. 10 and 8 t ha-1 improved the soil properties: ECe, pH, inorganic N, OM, and WHC higher than other treatments. While, 10 and 8 t PMC ha-1 also significantly increased leaf area index (LAI), crop growth rate (CGR) and net assimilation rate (NAR), and stover yield. Similarly, 10 and 8 t PMC ha-1 also improved the grain protein content, but contrarily, grain oil was lowest for 10 and 8 t ha-1 PMC during both years. Moreover, in both years highest gross and net income, and benefit cost ratio was also achieved by 10 and 8 t ha-1 PMC. It is concluded that PMC at rate of 10 and 8 t ha-1 sustainably improved soil properties and maize performance.

Keywords: compost, soil, maize, growth, yield

Procedia PDF Downloads 352

Authors: Olesia Mikhailova, Pavel Rovnaník

Abstract:

In the present work, metakaolin-based geopolymer including different polymer admixtures was studied. Different types of commercial polymer admixtures VINNAPAS^® and polyethylene glycol of different relative molecular weight were used as polymer admixtures. The main objective of this work is to investigate the influence of different types of admixtures on the properties of metakaolin-based geopolymer mortars considering their different dosage. Mechanical properties, such as flexural and compressive strength were experimentally determined. Also, study of the microstructure of selected specimens by using a scanning electron microscope was performed. The results showed that the specimen with addition of 1.5% of VINNAPAS^® 7016 F and 10% of polyethylene glycol 400 achieved maximum mechanical properties.

Keywords: geopolymer, mechanical properties, metakaolin, microstructure, polymer admixtures, porosity

Procedia PDF Downloads 230