Search results for: topological defects

Authors: Muhammad Naveed Ali, Hamad Bin Rashid, Muhammad Arif Khan, Abdul Basit, Hafiz Muhammad Arshad

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Abdominal defects are very common in pigeons. A new technique is known as intraabdominal mesh transplant that give better protection for herniorrhaphy. The aim of this study was to determine the performance of hernia mesh. In this study, an efficacy of two synthetic hernia mesh implants viz. conventional Prolene and a lightweight mesh monofilament polyester were assessed for the abdominal wall repair in pigeons. Twenty four healthy pigeons were selected and randomly distributed into three groups, A, B and C (n=8). In all groups, experimental laparotomy was performed; thereafter, abdominal muscles and peritoneum were sutured together, while, a 2 x 2 cm defect was created in the abdominal muscles. For onlay hernioplasty, the hernia mesh (Prolene mesh: group A; Polyester mesh: group B) was implanted over the external oblique muscles of the abdomen. In group C (control), the mesh was not implanted; instead, the laparotomy incision was closed after a herniorrhaphy. Post-operative pain wound healing, adhesion formation, histopathological findings and formation of hematoma, abscess and seroma were assessed as short-term complications. Post-operatively, pain at surgical site was significantly less (P < 0.001) in group B (Polyester mesh); wound healing was also significantly better and rapid in group B (P < 0.05) than in group A (Prolene mesh). Group B (Polyester mesh) also depicted less than 25% adhesions when assessed on the basis of a Quantitative Modified Diamond scale; a Qualitative Adhesion Tenacity scale also depicted either no adhesions or flimsy adhesions (n=2) in group B (Polyester mesh), in contrast to group A (Prolene), which manifested greater adhesion formation and presence of dense adhesions requiring blunt dissection. There were observed hematoma, seroma and abscess formations in birds treated by Prolene mesh only. Conclusively, the polyester mesh proved superior to the Prolene mesh regarding lesser adhesion, better in wound healing, and no short-term follow-up complications.

Keywords: adhesion, mesh, polyester, prolene

Procedia PDF Downloads 225

Authors: Farhan A. Alenizi

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Digital watermarking has evolved in the past years as an important means for data authentication and ownership protection. The images and video watermarking was well known in the field of multimedia processing; however, 3D objects' watermarking techniques have emerged as an important means for the same purposes, as 3D mesh models are in increasing use in different areas of scientific, industrial, and medical applications. Like the image watermarking techniques, 3D watermarking can take place in either space or transform domains. Unlike images and video watermarking, where the frames have regular structures in both space and temporal domains, 3D objects are represented in different ways as meshes that are basically irregular samplings of surfaces; moreover, meshes can undergo a large variety of alterations which may be hard to tackle. This makes the watermarking process more challenging. While the transform domain watermarking is preferable in images and videos, they are still difficult to implement in 3d meshes due to the huge number of vertices involved and the complicated topology and geometry, and hence the difficulty to perform the spectral decomposition, even though significant work was done in the field. Spatial domain watermarking has attracted significant attention in the past years; they can either act on the topology or on the geometry of the model. Exploiting the statistical characteristics in the 3D mesh models from both geometrical and topological aspects was useful in hiding data. However, doing that with minimal surface distortions to the mesh attracted significant research in the field. A 3D mesh blind watermarking technique is proposed in this research. The watermarking method depends on modifying the vertices' positions with respect to the center of the object. An optimal method will be developed to reduce the errors, minimizing the distortions that the 3d object may experience due to the watermarking process, and reducing the computational complexity due to the iterations and other factors. The technique relies on the displacement process of the vertices' locations depending on the modification of the variances of the vertices’ norms. Statistical analyses were performed to establish the proper distributions that best fit each mesh, and hence establishing the bins sizes. Several optimizing approaches were introduced in the realms of mesh local roughness, the statistical distributions of the norms, and the displacements in the mesh centers. To evaluate the algorithm's robustness against other common geometry and connectivity attacks, the watermarked objects were subjected to uniform noise, Laplacian smoothing, vertices quantization, simplification, and cropping. Experimental results showed that the approach is robust in terms of both perceptual and quantitative qualities. It was also robust against both geometry and connectivity attacks. Moreover, the probability of true positive detection versus the probability of false-positive detection was evaluated. To validate the accuracy of the test cases, the receiver operating characteristics (ROC) curves were drawn, and they’ve shown robustness from this aspect. 3D watermarking is still a new field but still a promising one.

Keywords: watermarking, mesh objects, local roughness, Laplacian Smoothing

Procedia PDF Downloads 138

Authors: T. H. Huang, C. Y. Gao, C. H. Lin, J. L. Kwo, Y. K. Tseng

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The design and reliability of solar photovoltaic modules are crucial to the development of solar energy, and efforts are still being made to extend the life of photovoltaic modules to improve their efficiency because natural aging is time-consuming and does not provide manufacturers and investors with timely information, accelerated aging is currently the best way to estimate the life of photovoltaic modules. In this study, the accelerated aging of different light sources was combined with spectral response measurements to understand the effect of light sources on aging tests. In this study, there are two types of experimental samples: packaged and unpackaged and then irradiated with full-spectrum and UVC light sources for accelerated aging, as well as a control group without aging. The full-spectrum aging was performed by irradiating the solar cell with a xenon lamp like the solar spectrum for two weeks, while the accelerated aging was performed by irradiating the solar cell with a UVC lamp for two weeks. The samples were first visually observed, and infrared thermal images were taken, and then the electrical (IV) and Spectral Responsivity (SR) data were obtained by measuring the spectral response of the samples, followed by Scanning Electron Microscopy (SEM), Raman spectroscopy (Raman), and X-ray Diffraction (XRD) analysis. The results of electrical (IV) and Spectral Responsivity (SR) and material analyses were used to compare the differences between packaged and unpackaged solar cells with full spectral aging, accelerated UVC aging, and unaged solar cells. The main objective of this study is to compare the difference in the aging of packaged and unpackaged solar cells by irradiating different light sources. We determined by infrared thermal imaging that both full-spectrum aging and UVC accelerated aging increase the defects of solar cells, and IV measurements demonstrated that the conversion efficiency of solar cells decreases after full-spectrum aging and UVC accelerated aging. SEM observed some scorch marks on both unpackaged UVC accelerated aging solar cells and unpackaged full-spectrum aging solar cells. Raman spectroscopy examines the Si intensity of solar cells, and XRD confirms the crystallinity of solar cells by the intensity of Si and Ag winding peaks.

Keywords: solar cell, aging, spectral response measurement

Procedia PDF Downloads 78

Authors: Shivdayal Patel, Suhail Ahmad

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Safety assurance and failure prediction of composite material component of an offshore structure due to low velocity impact is essential for associated risk assessment. It is important to incorporate uncertainties associated with material properties and load due to an impact. Likelihood of this hazard causing a chain of failure events plays an important role in risk assessment. The material properties of composites mostly exhibit a scatter due to their in-homogeneity and anisotropic characteristics, brittleness of the matrix and fiber and manufacturing defects. In fact, the probability of occurrence of such a scenario is due to large uncertainties arising in the system. Probabilistic finite element analysis of composite plates due to low-velocity impact is carried out considering uncertainties of material properties and initial impact velocity. Impact-induced damage of composite plate is a probabilistic phenomenon due to a wide range of uncertainties arising in material and loading behavior. A typical failure crack initiates and propagates further into the interface causing de-lamination between dissimilar plies. Since individual crack in the ply is difficult to track. The progressive damage model is implemented in the FE code by a user-defined material subroutine (VUMAT) to overcome these problems. The limit state function is accordingly established while the stresses in the lamina are such that the limit state function (g(x)>0). The Gaussian process response surface method is presently adopted to determine the probability of failure. A comparative study is also carried out for different combination of impactor masses and velocities. The sensitivity based probabilistic design optimization procedure is investigated to achieve better strength and lighter weight of composite structures. Chain of failure events due to different modes of failure is considered to estimate the consequences of failure scenario. Frequencies of occurrence of specific impact hazards yield the expected risk due to economic loss.

Keywords: composites, damage propagation, low velocity impact, probability of failure, uncertainty modeling

Procedia PDF Downloads 257

Authors: Noreen Noreen, Aamir Ijaz, Hamza Akhtar

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Background: Screening plays a major role to detect chromosomal abnormalities, Down syndrome, neural tube defects and other inborn diseases of the newborn. Serum biomarkers in the second trimester are useful in determining risk of most common chromosomal anomalies; these test include Alpha-fetoprotein (AFP), Human chorionic gonadotropin (hCG), Unconjugated Oestriol (UEȝ)and inhibin-A. Quadruple biomarkers are worth test in diagnosing the congenital pathology during pregnancy, these procedures does not form a part of routine health care of pregnant women in Pakistan, so the median value is lacking for population in Pakistan. Objective: To determine median values of biochemical maternal serum markers in local population during second trimester maternal screening. Study settings: Department of Chemical Pathology and Endocrinology, Armed Forces Institute of Pathology (AFIP) Rawalpindi. Methods: Cross-Sectional study for estimation of reference values. Non-probability consecutive sampling, 155 healthy pregnant women, of 30-40 years of age, will be included. As non-parametric statistics will be used, the minimum sample size is 120. Result: Total 155 women were enrolled into this study. The age of all women enrolled ranged from 30 to39 yrs. Among them, 39 per cent of women were less than 34 years. Mean maternal age 33.46±2.35 SD and maternal body weight were 54.98±2.88. Median value of quadruple markers calculated from 15-18th week of gestation that will be used for calculation of MOM for screening of trisomy21 in this gestational age. Median value at 15 week of gestation were observed hCG 36650 mIU/ml, AFP 23.3 IU/ml, UEȝ 3.5 nmol/L, InhibinA 198 ng/L, at 16 week of gestation hCG 29050 mIU/ml, AFP 35.4 IU/ml, UEȝ 4.1 nmol/L, InhibinA 179 ng/L, at 17 week of gestation hCG 28450 mIU/ml, AFP 36.0 IU/ml, UEȝ 6.7 nmol/L, InhibinA 176 ng/L and at 18 week of gestation hCG 25200 mIU/ml, AFP 38.2 IU/ml, UEȝ 8.2 nmol/L, InhibinA 190 ng/L respectively.All the comparisons were significant (p-Value <0.005) with 95% confidence Interval (CI) and level of significance of study set by going through literature and set at 5%. Conclusion: The median values for these four biomarkers in Pakistani pregnant women can be used to calculate MoM.

Keywords: screening, down syndrome, quadruple test, second trimester, serum biomarkers

Procedia PDF Downloads 154

Authors: Amirul Adlan, Robert McCulloch, Scott Evans, Michael Parry, Jonathan Stevenson, Lee Jeys

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Background and Objectives: The gastrocnemius myofascial flap is used to manage soft-tissue defects over the anterior aspect of the knee in the context of a patient presenting with a sinus and periprosthetic joint infection (PJI) or extensor mechanism failure. The aim of this study was twofold: firstly, to evaluate the outcomes of gastrocnemius flaps performed by appropriately trained orthopaedic surgeons in the context of PJI and, secondly, to evaluate the infection-free survival of this patient group. Methods: We retrospectively reviewed 30 patients who underwent gastrocnemius flap reconstruction during staged revision total knee arthroplasty for prosthetic joint infection (PJI). All flaps were performed by an orthopaedic surgeon with orthoplastics training. Patients had a mean age of 68.9 years (range 50–84) and were followed up for a mean of 50.4 months (range 2–128 months). A total of 29 patients (97 %) were categorized into Musculoskeletal Infection Society (MSIS) local extremity grade 3 (greater than two compromising factors), and 52 % of PJIs were polymicrobial. The primary outcome measure was flap failure, and the secondary outcome measure was a recurrent infection. Results: Flap survival was 100% with no failures or early returns to theatre for flap problems such as necrosis or haematoma. Overall infection-free survival during the study period was 48% (13 of 27 infected cases). Using limb salvage as the outcome, 77% (23 of 30 patients) retained the limb. Infection recurrence occurred in 48% (10 patients) in the type B3 cohort and 67% (4 patients) in the type C3 cohort (p = 0.65). Conclusion: The surgical technique for a gastrocnemius myofascial flap is reliable and reproducible when performed by appropriately trained orthopaedic surgeons, even in high-risk groups. However, the risks of recurrent infection and amputation remain high within our series due to poor host and extremity factors.

Keywords: gastrocnemius flap, limb salvage, revision arthroplasty, outcomes

Procedia PDF Downloads 89

Authors: Tiantian Min, Chuanxiang Cheng, Jin Yue

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The growth and reproduction of microorganisms in food packaging can cause food decay and foodborne diseases, which pose a serious threat to the health of consumers and even cause serious economic losses. Active food packaging containing antibacterial bioactive compounds is a promising strategy for extending the shelf life of products and maintaining the food quality, as well as reducing the food waste. However, most active packaging can only act as slow-release effect for antimicrobials, which causes the release rate of antimicrobials not match the growth rate of microorganisms. Stimuli-responsive active packaging materials based on biopolymeric substrates and bioactive substances that respond to some biological and non-biological trigger factors provide more opportunities for fresh food preservation. The biological stimuli factors such as relative humidity, pH and enzyme existed in the exudate secreted by microorganisms have been expected to design food packaging materials. These stimuli-responsive materials achieved accurate release or delivery of bioactive substances at specific time and appropriate dose. Recently, metal-organic-frameworks (MOFs) nanoparticles become attractive carriers to enhance the efficiency of bioactive compounds or drugs. Cellulose nanofibrils have been widely applied for film substrates due to their biodegradability and biocompatibility. The abundant hydroxyl groups in cellulose can be oxidized to carboxyl groups by TEMPO, making it easier to anchoring MOFs and to be further modification. In this study, a pH and enzyme dual-responsive CAR@ZIF-8/TOCNF/PE film was fabricated by in-situ growth of ZIF-8 nanoparticles onto TEMPO-oxidized cellulose (TOCNF) film and further coated with pectin (PE) for stabilization and controlled release of carvacrol (CAR). The enzyme triggered release of CAR was achieved owing to the degradation of pectin by pectinase secreted by microorganisms. Similarly, the pH-responsive release of CAR was attributed to the unique skeleton degradation of ZIF-8, further accelerating the release of CAR from the topological structure of ZIF-8. The composite film performed excellent crystallinity and adsorb ability confirmed by X-ray diffraction and BET analysis, and the inhibition efficiency against Escherichia coli, Staphylococcus aureus and Aspergillus niger reached more than 99%. The composite film was capable of releasing CAR when exposure to dose-dependent enzyme (0.1, 0.2, and 0.3 mg/mL) and acidic condition (pH = 5). When inoculated 10 μL of Aspergillus niger spore suspension on the equatorial position of mango and raspberries, this composite film acted as packaging pads effectively inhibited the mycelial growth and prolonged the shelf life of mango and raspberries to 7 days. Such MOF-TOCNF based film provided a targeted, controlled and sustained release of bioactive compounds for long-term antibacterial activity and preservation effect, which can also avoid the cross-contamination of fruits.

Keywords: active food packaging, controlled release, fruit preservation, in-situ growth, stimuli-responsive

Procedia PDF Downloads 37

Authors: Wei Xu, Abdo S. Haidar, Jianxin Gao

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Prosthetic socket is a component that connects the residual limb of an amputee with an artificial prosthesis. It is widely recognized as the most critical component that determines the comfort of a patient when wearing the prosthesis in his/her daily activities. Through the socket, the body weight and its associated dynamic load are distributed and transmitted to the prosthesis during walking, running or climbing. In order to achieve a good-fit socket for an individual amputee, it is essential to obtain the biomechanical properties of the residual limb. In current clinical practices, this is achieved by a touch-and-feel approach which is highly subjective. Although there have been significant advancements in prosthetic technologies such as microprocessor controlled knee and ankle joints in the last decade, the progress in designing a comfortable socket has been rather limited. This means that the current process of socket design is still very time-consuming, and highly dependent on the expertise of the prosthetist. Supported by the state-of-the-art sensor technologies and numerical simulations, a new socket design system is being developed to help prosthetists achieve rapid design of comfortable sockets for above knee amputees. This paper reports the research work related to establishing biomechanical models for socket design. Through numerical simulation using finite element method, comprehensive relationships between pressure on residual limb and socket geometry were established. This allowed local topological adjustment for the socket so as to optimize the pressure distributions across the residual limb. When the full body weight of a patient is exerted on the residual limb, high pressures and shear forces between the residual limb and the socket occur. During numerical simulations, various hyperplastic models, namely Ogden, Yeoh and Mooney-Rivlin, were used, and their effectiveness in representing the biomechanical properties of soft tissues of the residual limb was evaluated. This also involved reverse engineering, which resulted in an optimal representative model under compression test. To validate the simulation results, a range of silicone models were fabricated. They were tested by an indentation device which yielded the force-displacement relationships. Comparisons of results obtained from FEA simulations and experimental tests showed that the Ogden model did not fit well the soft tissue material indentation data, while the Yeoh model gave the best representation of the soft tissue mechanical behavior under indentation. Compared with hyperplastic model, the result showed that elastic model also had significant errors. In addition, normal and shear stress distributions on the surface of the soft tissue model were obtained. The effect of friction in compression testing and the influence of soft tissue stiffness and testing boundary conditions were also analyzed. All these have contributed to the overall goal of designing a good-fit socket for individual above knee amputees.

Keywords: above knee amputee, finite element simulation, hyperplastic model, prosthetic socket

Procedia PDF Downloads 178

Authors: Yugander Arra, Florence Auguy, Melissa Stiebner, Sophie Chéron, Michael M. Wudick, Van Schepler-Luu, Sébastien Cunnac, Wolf B. Frommer, Laurence Albar

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Rice yellow mottle virus (RYMV) is one of the most important diseases affecting rice in Africa. The most promising strategy to reduce yield losses is the use of highly resistant varieties. The resistance gene RYMV2 is homolog of the Arabidopsis constitutive expression of pathogenesis related protein-5 (AtCPR5) nucleoporin gene. Resistance alleles are originating from African cultivated rice Oryza glaberrima, rarely cultivated, and are characterized by frameshifts or early stop codons, leading to a non-functional or truncated protein. Rice possesses two paralogs of CPR5 and function of these genes are unclear. Here, we evaluated the role of the two rice candidate nucleoporin paralogs OsCPR5.1 (pathogenesis-related gene 5; RYMV2) and OsCPR5.2 by CRISPR/Cas9 genome editing. Despite striking sequence and structural similarity, only loss-of-function of OsCPR5.1 led to full resistance, while loss-of-function oscpr5.2 mutants remained susceptible. Short N-terminal deletions in OsCPR5.1 also did not lead to resistance. In contrast to Atcpr5 mutants, neither OsCPR5.1 nor OsCPR5.2 knock out mutants showed substantial growth defects. Taken together, the candidate nucleoporin OsCPR5.1, but not its close homolog OsCPR5.2, plays a specific role for the susceptibility to RYMV, possibly by impairing the import of viral RNA or protein into the nucleus. Whereas gene introgression from O. glaberrima to high yielding O. sativa varieties is impaired by strong sterility barriers and the negative impact of linkage drag, genome editing of OsCPR5.1, while maintaining OsCPR5.2 activity, thus provides a promising strategy to generate O. sativa elite lines that are resistant to RYMV.

Keywords: CRISPR Cas9, genome editing, knock out mutant, recessive resistance, rice yellow mottle virus

Procedia PDF Downloads 88

Authors: A. Bajek, J. Skopinska-Wisniewska, A. Rynkiewicz, A. Jundzill, M. Bodnar, A. Marszalek, T. Drewa

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Traumatic injury and age-related degenerative diseases associated with cartilage are major health problems worldwide. The articular cartilage is comprised of a relatively small number of cells, which have a relatively slow rate of turnover. Therefore, damaged articular cartilage has a limited capacity for self-repair. New clinical methods have been designed to achieve better repair of injured cartilage. However, there is no treatment that enables full restoration of it. The aim of this study was to evaluate how collagen gel with bone marrow mesenchymal stem cells (MSCs) and collagen gel alone will influence on the hip cartilage repair after injury. Collagen type I was isolated from rats’ tails and cross-linked with N-hydroxysuccinimide in 24-hour process. MSCs were isolated from rats’ bone marrow. The experiments were conducted according to the guidelines for animal experiments of Ethics Committee. Fifteen 8-week-old Wistar rats were used in this study. All animals received hip joint surgery with a total of 30 created cartilage defects. Then, animals were randomly divided into three groups and filled, respectively, with collagen gel (group 1), collagen gel cultured with MSCs (group II) or left untreated as a control (control group). Immunohistochemy and radiological evaluation was carried out 11 weeks post implantation. It has been proved that the surface of the matrix is non-toxic, and its porosity promotes cell adhesion and growth. However, the in vivo regeneration process was poor. We observed the low integration rate of biomaterial. Immunohistochemical evaluation of cartilage after 11 weeks of treatment showed low II and high X collagen expression in two tested groups in comparison to the control one, in which we observed the high II collagen expression. What is more, after radiological analysis, we observed the best regeneration process in control group. The biomaterial construct and mesenchymal stem cells, as well as the use of the biomaterial itself was not sufficient to regenerate the hip cartilage surfaces. These results suggest that the collagen gel based biomaterials, even with MSCs, are not satisfactory in repar of hip cartilage defect. However, additional evaluation is needed to confirm these results.

Keywords: collafen gel, MSCs, cartilage repair, hip cartilage

Procedia PDF Downloads 435

Authors: Chakrapani Pullagummi, Arun Jyothi Bheemagani, B. Chandra Sekhar Singh, Prem Kumar, A. Roja Rani

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Diabetes mellitus describes a metabolic disorder of multiple aetiology characterized by chronic hyperglycaemia with disturbances of carbohydrate, fat and protein metabolism resulting from defects in insulin secretion and its action. The objective of present study was alloxan induced diabetes in S.D (Sprague Dawley) rats, treated with leaf extract of Andrographis paniculata and bark extract of Erythrina indica. Plant extract treated rats were analyzed biochemically and molecularly. on normal and diabetic rats. The changes in MDA (lipid peroxidation) and glucose (by GOD method) levels in blood of both normal and diabetic rat were analyzed. Diabetes induced rats were treated with methanolic extracts of Andrographis paniculata leaf and Erythrina indica bark which are of medicinal importance. Later after inducing diabetes the rats were treated with medicinal plant extracts, Andrographis paniculata leaf and Erythrina indica bark which are well known for their anti diabetic and antioxidative property in order to control the glucose and MDA levels. The blood plasma of diabetic and normal rats was analyzed for the levels of MDA (lipid peroxidation) and glucose levels. Results of this study suggested that the Andrographis paniculata leaf and Erythrina indica can be used as a potential natural antidiabetic agent for treating and postponing the appearance of complications that arise due to Diabetes. Molecular study deals with the analysis of binding mechanism of 2 selected natural compounds from Andrographis and Erythrina extracts against the novel target for type T2D namely PPAR-γ compared with Rosiglitazone (standard compound). The results revealed that most of the selected herbal lead compounds were effective targets against the receptors. These compounds showed favorable interactions with the amino acid residues thereby substantiating their proven efficacy as anti-diabetic compounds.

Keywords: andrographis paniculata, erythrina indica, alloxan, lipid peroxidation, blood glucose level, PPAR-γ

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Authors: Dong-Gi Lee, Suyeon Cha, Yong-Sun Bahn

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Sterol lipid is essential for cell membrane structure in eukaryotic cells. In mammalian cells, sterol regulatory element binding proteins (SREBPs) act as principal regulators of cellular cholesterol which is essential for proper cell membrane fluidity and structure. SREBP and sterol regulation are related to levels of cellular oxygen because it is a major substrate for sterol synthesis. Upon cellular sterol and oxygen levels are depleted, SREBP is translocated to the Golgi where it undergoes proteolytic cleavage of N terminus, then it travels to the nucleus to play a role as transcription factor. In yeast cells, synthesis of ergosterol is also highly oxygen consumptive, and Sre1 is a transcription factor known to play a central role in adaptation to growth under low oxygen condition and sterol homeostasis in Cryptococcus neoformans. In this study, we observed phenotypes in other strains of Cryptococcus species by constructing hob1Δ and sre1Δ mutants to confirm whether the functions of both genes are conserved in most serotypes. As a result, hob1Δ showed no noticeable phenotype under treatment of antifungal drugs and most environmental stresses in R265 (C. gattii) and XL280 (C. neoformans), suggesting that Hob1 is related to sterol regulation only in H99 (serotype A). On the other hand, the function of Sre1 was found to be conserved in most serotypes. Furthermore, mating experiment of hob1Δ or sre1Δ showed dramatic defects in serotype A (H99) and D (XL280). It revealed that Hob1 and Sre1 related to mating ability in Cryptococcus species, especially cell fusion efficiency. In conclusion, HOB1 and SRE1 play crucial role in regulating sterol-homeostasis and differentiation in C. neoformans, moreover, Hob1 is specific gene in Cryptococcus neoformans. It suggests that Hob1 is considered as potent factor-targeted new safety antifungal drug.

Keywords: cryptococcus neoformans, Hob1, Sre1, sterol regulatory element binding proteins

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Authors: Alexander A. Karabutov, Natalia B. Podymova, Elena B. Cherepetskaya

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The theoretical analysis is carried out to get the relation between the ultrasonic wave velocity and the value of residual stresses. The laser-ultrasonic method is developed to evaluate the residual stresses and subsurface defects in metals. The method is based on the laser thermooptical excitation of longitudinal ultrasonic wave sand their detection by a broadband piezoelectric detector. A laser pulse with the time duration of 8 ns of the full width at half of maximum and with the energy of 300 µJ is absorbed in a thin layer of the special generator that is inclined relative to the object under study. The non-uniform heating of the generator causes the formation of a broadband powerful pulse of longitudinal ultrasonic waves. It is shown that the temporal profile of this pulse is the convolution of the temporal envelope of the laser pulse and the profile of the in-depth distribution of the heat sources. The ultrasonic waves reach the surface of the object through the prism that serves as an acoustic duct. At the interface ‚laser-ultrasonic transducer-object‘ the conversion of the most part of the longitudinal wave energy takes place into the shear, subsurface longitudinal and Rayleigh waves. They spread within the subsurface layer of the studied object and are detected by the piezoelectric detector. The electrical signal that corresponds to the detected acoustic signal is acquired by an analog-to-digital converter and when is mathematically processed and visualized with a personal computer. The distance between the generator and the piezodetector as well as the spread times of acoustic waves in the acoustic ducts are the characteristic parameters of the laser-ultrasonic transducer and are determined using the calibration samples. There lative precision of the measurement of the velocity of longitudinal ultrasonic waves is 0.05% that corresponds to approximately ±3 m/s for the steels of conventional quality. This precision allows one to determine the mechanical stress in the steel samples with the minimal detection threshold of approximately 22.7 MPa. The results are presented for the measured dependencies of the velocity of longitudinal ultrasonic waves in the samples on the values of the applied compression stress in the range of 20-100 MPa.

Keywords: laser-ultrasonic method, longitudinal ultrasonic waves, metals, residual stresses

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Authors: Nivatha Elangovan, Lakshman Neelakantan, Murugaiyan Amirthalingam

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Magnesium and its alloys are widely used for various lightweight engineering and biomedical applications as they render high strength to low weight ratio and excellent corrosion resistance. These alloys possess good bio-compatibility and similar mechanical properties to natural bone. However, manufacturing magnesium alloy components by conventional formative and subtractive methods is challenging due to their poor castability, oxidation potential, and machinability. Therefore, efforts are made to produce complex-design containing magnesium alloy components by additive manufacturing (AM). Arc-wire directed energy deposition (AW-DED), also known as wire arc additive manufacturing (WAAM), is more attractive to produce large volume components with increased productivity than any other AM technique. In this research work, efforts were made to optimise the deposition parameters to build thick-walled (about 10 mm) AZ31 magnesium alloy components by a gas metal arc (GMA) based AW-DED process. By using controlled dip short-circuiting metal transfer in a GMA process, depositions were carried out without defects and spatter formation. Current and voltage waveforms were suitably modified to achieve stable metal transfer. Moreover, the droplet transfer behaviour was analysed using high-speed image analysis and correlated with arc energy. Optical and scanning electron microscopy analyses were carried out to correlate the influence of deposition parameters with the microstructural evolution during deposition. The investigation reveals that by carefully controlling the current-voltage waveform and droplet transfer behaviour, it is possible to stabilise equiaxed grain microstructures in the deposited AZ31 components. The printed component exhibited an improved mechanical property as equiaxed grains improve the ductility and enhance the toughness. The equiaxed grains in the component improved the corrosion-resistant behaviour of other conventionally manufactured components.

Keywords: arc wire directed energy deposition, AZ31 magnesium alloy, equiaxed grain, corrosion

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Authors: Bijit Kalita, R. Jayaganthan

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Additive manufacturing (AM) is a novel manufacturing method which provides more freedom in design, manufacturing near-net-shaped parts as per demand, lower cost of production, and expedition in delivery time to market. Among various metals, AM techniques, Laser Powder Bed Fusion (L-PBF) is the most prominent one that provides higher accuracy and powder proficiency in comparison to other methods. Particularly, 17-4 PH alloy is martensitic precipitation hardened (PH) stainless steel characterized by resistance to corrosion up to 300°C and tailorable strengthening by copper precipitates. Additively manufactured 17-4 PH stainless steel exhibited a dendritic/cellular solidification microstructure in the as-built condition. It is widely used as a structural material in marine environments, power plants, aerospace, and chemical industries. The excellent weldability of 17-4 PH stainless steel and its ability to be heat treated to improve mechanical properties make it a good material choice for L-PBF. In this study, the microstructures of martensitic stainless steels in the as-built state, as well as the effects of process parameters, building atmosphere, and heat treatments on the microstructures, are reviewed. Mechanical properties of fabricated parts are studied through micro-hardness and tensile tests. Tensile tests are carried out under different strain rates at room temperature. In addition, the effect of process parameters and heat treatment conditions on mechanical properties is critically reviewed. These studies revealed the performance of L-PBF fabricated 17–4 PH stainless-steel parts under cyclic loading, and the results indicated that fatigue properties were more sensitive to the defects generated by L-PBF (e.g., porosity, microcracks), leading to the low fracture strains and stresses under cyclic loading. Rapid melting, solidification, and re-melting of powders during the process and different combinations of processing parameters result in a complex thermal history and heterogeneous microstructure and are necessary to better control the microstructures and properties of L-PBF PH stainless steels through high-efficiency and low-cost heat treatments.

Keywords: 17–4 PH stainless steel, laser powder bed fusion, selective laser melting, microstructure, additive manufacturing

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Authors: K. M. Damodara Gowda

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Background: Maternal health and nutrition are considered as the predominant factors influencing brain functional development. If the mother is free of illness and genetic defects, maternal nutrition would be one of the most critical factors affecting the brain development. Calorie restrictions cause significant impairment in spatial learning ability and the levels of Brain Derived Neurotrophic Factor (BDNF) in rats. But, the mechanism by which the prenatal under-nutrition leads to impairment in brain learning and memory function is still unclear. In the present study, prenatal Astaxanthin supplementation on BDNF level, spatial learning and memory performance in the offspring’s of normal, calorie restricted and Astaxanthin supplemented rats was investigated. Methodology: The rats were administered with 6mg and 12 mg of astaxanthin /kg bw for 21 days following which acquisition and retention of spatial memory was tested in a partially-baited eight arm radial maze. The BDNF level in different regions of the brain (cerebral cortex, hippocampus and cerebellum) was estimated by ELISA method. Results: Calorie restricted animals treated with astaxanthin made significantly more correct choices (P < 0.05), and fewer reference memory errors (P < 0.05) on the tenth day of training compared to offsprings of calorie restricted animals. Calorie restricted animals treated with astaxanthin also made significantly higher correct choices (P < 0.001) than untreated calorie restricted animals in a retention test 10 days after the training period. The mean BDNF level in cerebral cortex, Hippocampus and cerebellum in Calorie restricted animals treated with astaxanthin didnot show significant variation from that of control animals. Conclusion: Findings of the study indicated that memory and learning was impaired in the offspring’s of calorie restricted rats which was effectively modulated by astaxanthin at the dosage of 12 mg/kg body weight. In the same way the BDNF level at cerebral cortex, Hippocampus and Cerebellum was also declined in the offspring’s of calorie restricted animals, which was also found to be effectively normalized by astaxanthin.

Keywords: calorie restiction, learning, Memory, Cerebral cortex, Hippocampus, Cerebellum, BDNF, Astaxanthin

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Authors: Minhyuk Heo, Jihwan Yun, Seonghun Park

Abstract:

It has been reported that intervertebral fusion surgery, which removes most of the ligaments and muscles of the spine, increases the degenerative disease in adjacent spinal segments. Therefore, it is required to develop a lumbar interspinous process fixation device that minimizes the risks and side effects from the surgery. The objective of the current study is to design an interspinous process fixation device with simple structures in order to minimize soft tissue removal and operation time during intervertebral fusion surgery. For the design concepts of a lumbar fixation device, the principle of the ratchet was first applied on the joining parts of the device in order to shorten the operation time. The coil spring structure was selected for connecting parts between the spinous processes so that a normal range of motion in spinal segments is preserved and degenerative spinal diseases are not developed in the adjacent spinal segments. The stiffness of the spring was determined not to interrupt the motion of a lumbar spine. The designed value of the spring stiffness allows the upper part of the spring to move ~10° which is higher than the range of flexion and extension for normal lumbar spine (6°-8°), when a moment of 10Nm is applied on the upper face of L1. A finite element (FE) model composed of L1 to L5 lumbar spines was generated to verify the mechanical integrity and the dynamic stability of the designed lumbar fixation device and to further optimize the lumbar fixation device. The FE model generated above produced the same pressure value on intervertebral disc and dynamic behavior as the normal intact model reported in the literature. The consistent results from this comparison validates the accuracy in the modeling of the current FE model. Currently, we are trying to generate an abnormal model with defects in one or more components of the normal FE model above. Then, the mechanical integrity and the dynamic stability of the designed lumbar fixation device will be analyzed after being installed in the abnormal model and then the lumbar fixation device will be further optimized.

Keywords: lumbar interspinous process fixation device, finite element method, lumbar spine, kinematics

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Authors: Ishith Seth, Lyndel Hewitt, Takako Yabe, James Wykes, Jonathan Clark, Bruce Ashford

Abstract:

Background: Vastus lateralis (VL) can be used to reconstruct defects of the head and neck. Whilst the advantages are documented, donor-site morbidity is not well described. This study aimed to assess donor-site morbidity after VL flap harvest. The results will determine future directions for preventative and post-operative care to improve patient health outcomes. Methods: Ten participants (mean age 55 years) were assessed for the presence of donor-site morbidity after VL harvest. Musculoskeletal (pain, muscle strength, muscle length, tactile sensation), quality of life (SF-12), and lower limb function (lower extremity function, gait (function and speed), sit to stand were assessed using validated and standardized procedures. Outcomes were compared to age-matched healthy reference values or the non-operative side. Analyses were conducted using descriptive statistics and non-parametric tests. Results: There was no difference in muscle strength (knee extension), muscle length, ability to sit-to-stand, or gait function (all P > 0.05). Knee flexor muscle strength was significantly less on the operated leg compared to the non-operated leg (P=0.02) and walking speed was slower than age-matched healthy values (P<0.001). Thigh tactile sensation was impaired in 89% of participants. Quality of life was significantly less for the physical health component of the SF-12 (P<0.001). The mental health component of the SF-12 was similar to healthy controls (P=0.26). Conclusion: There was no effect on donor site morbidity with regards to knee extensor strength, pain, walking function, ability to sit-to-stand, and muscle length. VL harvest affected donor-site knee flexion strength, walking speed, tactile sensation, and physical health-related quality of life.

Keywords: vastus lateralis, morbidity, head and neck, surgery, donor-site morbidity

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Authors: Oyindamola Kayode, Sarah George, Roberto Borrageiro, Mike Shirran

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A phenomenon identified by our industrial partner has experienced sag on AA3104 can body stock (CBS) transfer bar during transportation of the slab from the breakdown mill to the finishing mill. Excessive sag results in bottom scuffing of the slab onto the roller table, resulting in surface defects on the final product. It has been found that increasing the strain rate on the breakdown mill final pass results in a slab resistant to sag. The creep response for materials hot deformed at different Zener–Holloman parameter values needs to be evaluated experimentally to gain better understanding of the operating mechanism. This study investigates this identified phenomenon through laboratory simulation of the breakdown mill conditions for various strain rates by utilizing the Gleeble at UCT Centre for Materials Engineering. The experiment will determine the creep response for a range of conditions as well as quantifying the associated material microstructure (sub-grain size, grain structure etc). The experimental matrices were determined based on experimental conditions approximate to industrial hot breakdown rolling and carried out on the Gleeble 3800 at the Centre for Materials Engineering, University of Cape Town. Plane strain compression samples were used for this series of tests at an applied load that allow for better contact and exaggerated creep displacement. A tantalum barrier layer was used for increased conductivity and decreased risk of anvil welding. One set of tests with no in-situ hold time was performed, where the samples were quenched after deformation. The samples were retained for microstructure analysis of the micrographs from the light microscopy (LM), quantitative data and images from scanning electron microscopy (SEM) and energy dispersive X-ray (EDX), sub-grain size and grain structure from electron back scattered diffraction (EBSD).

Keywords: aluminium alloy, can-body stock, hot rolling, creep response, Zener-Hollomon parameter

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Authors: Khimmatali Nomozovich Juraev

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Silicon carbide is one of the promising materials with potential applications in electronic devices using high power, high frequency and high electric field. Currently, silicon carbide is used to manufacture high power and frequency diodes, transistors, radiation detectors, light emitting diodes (LEDs) and other functional devices. In this work, the effects of magnetic field on p-n junctions based on 4H-SiC were experimentally studied. As a research material, monocrystalline silicon carbide wafers (Cree Research, Inc., USA) with relatively few growth defects grown by physical vapor transport (PVT) method were used: Nd dislocations 104 cm², Nm micropipes ~ 10–10² cm-², thickness ~ 300-600 μm, surface ~ 0.25 cm², resistivity ~ 3.6–20 Ωcm, the concentration of background impurities Nd − Na ~ (0.5–1.0)×1017cm-³. The initial parameters of the samples were determined on a Hall Effect Measurement System HMS-7000 (Ecopia) measuring device. Diffusing Ni nickel atoms were covered to the silicon surface of silicon carbide in a Universal Vacuum Post device at a vacuum of 10-⁵ -10-⁶ Torr by thermal sputtering and kept at a temperature of 600-650°C for 30 minutes. Then Ni atoms were diffused into the silicon carbide 4H-SiC sample at a temperature of 1150-1300°C by low temperature diffusion method in an air atmosphere, and the effects of the magnetic field on the I-V characteristics of the samples were studied. I-V characteristics of silicon carbide 4H-SiC p-n junction sample were measured in the magnetic field and in the absence of a magnetic field. The measurements were carried out under conditions where the magnitude of the magnetic field induction vector was 0.5 T. In the state, the direction of the current flowing through the diode is perpendicular to the direction of the magnetic field. From the obtained results, it can be seen that the magnetic field significantly affects the I-V characteristics of the p-n junction in the magnetic field when it is measured in the forward direction. Under the influence of the magnetic field, the change of the magnetic resistance of the sample of silicon carbide 4H-SiC p-n junction was determined. It was found that changing the magnetic field poles increases the direct forward current of the p-n junction or decreases it when the field direction changes. These unique electrical properties of the 4H-SiC p-n junction sample of silicon carbide, that is, the change of the sample's electrical properties in a magnetic field, makes it possible to fabricate magnetic field sensing devices based on silicon carbide to use at harsh environments in future. So far, the productions of silicon carbide magnetic detectors are not available in the industry.

Keywords: 4H-SiC, diffusion Ni, effects of magnetic field, I-V characteristics

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Authors: Elena B. Cherepetskaya, Alexander A. Karabutov, Natalia B. Podymova, Ivan Sas

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Nonlinear evolution of broadband ultrasonic pulses passed through the rock specimens is studied using the apparatus ‘GEOSCAN-02M’. Ultrasonic pulses are excited by the pulses of Q-switched Nd:YAG laser with the time duration of 10 ns and with the energy of 260 mJ. This energy can be reduced to 20 mJ by some light filters. The laser beam radius did not exceed 5 mm. As a result of the absorption of the laser pulse in the special material – the optoacoustic generator–the pulses of longitudinal ultrasonic waves are excited with the time duration of 100 ns and with the maximum pressure amplitude of 10 MPa. The immersion technique is used to measure the parameters of these ultrasonic pulses passed through a specimen, the immersion liquid is distilled water. The reference pulse passed through the cell with water has the compression and the rarefaction phases. The amplitude of the rarefaction phase is five times lower than that of the compression phase. The spectral range of the reference pulse reaches 10 MHz. The cubic-shaped specimens of the Karelian gabbro are studied with the rib length 3 cm. The ultimate strength of the specimens by the uniaxial compression is (300±10) MPa. As the reference pulse passes through the area of the specimen without cracks the compression phase decreases and the rarefaction one increases due to diffraction and scattering of ultrasound, so the ratio of these phases becomes 2.3:1. After preloading some horizontal cracks appear in the specimens. Their location is found by one-sided scanning of the specimen using the backward mode detection of the ultrasonic pulses reflected from the structure defects. Using the computer processing of these signals the images are obtained of the cross-sections of the specimens with cracks. By the increase of the reference pulse amplitude from 0.1 MPa to 5 MPa the nonlinear transformation of the ultrasonic pulse passed through the specimen with horizontal cracks results in the decrease by 2.5 times of the amplitude of the rarefaction phase and in the increase of its duration by 2.1 times. By the increase of the reference pulse amplitude from 5 MPa to 10 MPa the time splitting of the phases is observed for the bipolar pulse passed through the specimen. The compression and rarefaction phases propagate with different velocities. These features of the powerful broadband ultrasonic pulses passed through the rock specimens can be described by the hysteresis model of Preisach-Mayergoyz and can be used for the location of cracks in the optically opaque materials.

Keywords: cracks, geological materials, nonlinear evolution of ultrasonic pulses, rock

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Authors: Mohammad Nasb, Muhammad Rehan, Chen Hong

Abstract:

Background Meniscus defects critically alter knee function and lead to degenerative changes. Regenerative medicine applications including stem cell transplantation have showed a promising efficacy in finding alternatives to overcome traditional treatment limitations. However, stem cell therapy remains limited due to the substantially reduced viability and inhibitory microenvironment. Since tissue growth and repair are under the control of biochemical and mechanical signals, several approaches have recently been investigated (e.g., low intensity pulsed ultrasound [LIPUS]) to promote the regeneration process. This study employed LIPUS to improve growth and osteogenic differentiation of mesenchymal stem cells derived from human embryonic stem cells to improve the regeneration of meniscus tissue. Methodology: The Mesenchymal stromal cells (MSCs) were transplanted into the epicenter of the injured meniscus in rabbits, which were randomized into two main groups: a treatment group (n=32 New Zealand rabbits) including 4 subgroups of 8 rabbits in each subgroup (LIPUS treatment, MSC treatment, LIPUS with MSC and control), and a second group (n=9) to track implanted cells and their progeny using green fluorescence protein (GFP). GFP consists of the MSC and LIPUS-MSC combination subgroups. Rabbits were then subjected to histological, immunohistochemistry, and MRI assessment. Results: The quantity of the newly regenerated tissue in the combination treatment group that had Ultrasound irradiation after mesenchymal stem cells were better at all end points. Likewise, Tissue quality scores were also greater in knees treated with both approaches compared with controls and single treatment at all end points, achieving significance at twelve and twenty-four weeks [p < 0.05], and [p = 0.008] at twelve weeks. Differentiation into type-I and II collagen-expressing cells were higher in the combination group at up to twenty-four weeks. Conclusions: the combination of mesenchymal stem cells and LIPUS showed greater adhering to the sites of meniscus injury, differentiate into cells resembling meniscal fibrochondrocytes, and improve both quality and quantity of meniscal regeneration.

Keywords: stem cells, regenerative medicine, osteoarthritis, knee

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Authors: I. Sinnarasa, Y. Thimont, L. Presmanes, A. Barnabé

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The thermoelectricity is a promising technique to overcome the issues in recovering waste heat to electricity without using moving parts. In fact, the thermoelectric (TE) effect defines as the conversion of a temperature gradient directly into electricity and vice versa. To optimize TE materials, the power factor (PF = σS² where σ is electrical conductivity and S is Seebeck coefficient) must be increased by adjusting the carrier concentration, and/or the lattice thermal conductivity Kₜₕ must be reduced by introducing scattering centers with point defects, interfaces, and nanostructuration. The PF does not show the advantages of the thin film because it does not take into account the thermal conductivity. In general, the thermal conductivity of the thin film is lower than the bulk material due to their microstructure and increasing scattering effects with decreasing thickness. Delafossite type oxides CuᴵMᴵᴵᴵO₂ received main attention for their optoelectronic properties as a p-type semiconductor they exhibit also interesting thermoelectric (TE) properties due to their high electrical conductivity and their stability in room atmosphere. As there are few proper studies on the TE properties of Mg-doped CuCrO₂ thin films, we have investigated, the influence of the annealing temperature on the electrical conductivity and the Seebeck coefficient of Mg-doped CuCrO₂ thin films and calculated the PF in the temperature range from 40 °C to 220 °C. For it, we have deposited Mg-doped CuCrO₂ thin films on fused silica substrates by RF magnetron sputtering. This study was carried out on 300 nm thin films. The as-deposited Mg doped CuCrO₂ thin films have been annealed at different temperatures (from 450 to 650 °C) under primary vacuum. Electrical conductivity and Seebeck coefficient of the thin films have been measured from 40 to 220 °C. The highest electrical conductivity of 0.60 S.cm⁻¹ with a Seebeck coefficient of +329 µV.K⁻¹ at 40 °C have been obtained for the sample annealed at 550 °C. The calculated power factor of optimized CuCrO₂:Mg thin film was 6 µW.m⁻¹K⁻² at 40 °C. Due to the constant Seebeck coefficient and the increasing electrical conductivity with temperature it reached 38 µW.m⁻¹K⁻² at 220 °C that was a quite good result for an oxide thin film. Moreover, the degenerate behavior and the hopping mechanism of CuCrO₂:Mg thin film were elucidated. Their high and constant Seebeck coefficient in temperature and their stability in room atmosphere could be a great advantage for an application of this material in a high accuracy temperature measurement devices.

Keywords: thermoelectric, oxides, delafossite, thin film, power factor, degenerated semiconductor, hopping mode

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Authors: Azariah Sosa, Carlos Renedo Sanchez

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The development of a new motorway north of Auckland (New Zealand) includes steep rock cuts, from 63 up to 85 degrees, in an interbedded sandstone and siltstone rock mass of the geological unit Waitemata Group (Pakiri Formation), which shows sub-horizontal bedding planes, various sub-vertical joint sets, and a diverse weathering profile. In this kind of rock mass -that can be classified as a weak rock- the definition of the stable maximum geometry is not only governed by discontinuities and defects evident in the rock but is important to also consider the global stability of the rock slope, including (in the analysis) the rock mass characterisation, influence of the groundwater, the geological evolution, and the weathering processes. Depending on the weakness of the rock and the processes suffered, the global stability could, in fact, be a more restricting element than the potential instability of individual blocks through discontinuities. This paper discusses those elements that govern the stability of the rock slopes constructed in a rock formation with favourable bedding and distribution of discontinuities (horizontal and vertical) but with a weak behaviour in terms of global rock mass characterisation. In this context, classifications as Q-Slope and slope stability assessment methodology (SSAM) have been demonstrated as important tools which complement the assessment of the global stability together with the analytical tools related to the wedge-type failures and limit equilibrium methods. The paper focuses on the applicability of these two new empirical classifications to evaluate the slope stability in 18 already excavated rock slopes in the Pakiri formation through comparison between the predicted and observed stability issues and by reviewing the outcome of analytical methods (Rocscience slope stability software suite) compared against the expected stability determined from these rock classifications. This exercise will help validate such findings and correlations arising from the two empirical methods in order to adjust the methods to the nature of this specific kind of rock mass and provide a better understanding of the long-term stability of the slopes studied.

Keywords: Pakiri formation, Q-slope, rock slope stability, SSAM, weak rock

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Authors: Sairi Satari

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Introduction: Six-sigma is a metric that quantifies the performance of processes as a rate of Defects-Per-Million Opportunities. Sigma methodology can be applied in chemical pathology laboratory for evaluating process performance with evidence for process improvement in quality assurance program. In the laboratory, these methods have been used to improve the timeliness of troubleshooting, reduce the cost and frequency of quality control and minimize pre and post-analytical errors. Aim: The aim of this study is to evaluate the sigma values of the Cobas 8000 analyzer based on the minimum requirement of the specification. Methodology: Twenty-one analytes were chosen in this study. The analytes were alanine aminotransferase (ALT), albumin, alkaline phosphatase (ALP), Amylase, aspartate transaminase (AST), total bilirubin, calcium, chloride, cholesterol, HDL-cholesterol, creatinine, creatinine kinase, glucose, lactate dehydrogenase (LDH), magnesium, potassium, protein, sodium, triglyceride, uric acid and urea. Total error was obtained from Clinical Laboratory Improvement Amendments (CLIA). The Bias was calculated from end cycle report of Royal College of Pathologists of Australasia (RCPA) cycle from July to December 2016 and coefficient variation (CV) from six-month internal quality control (IQC). The sigma was calculated based on the formula :Sigma = (Total Error - Bias) / CV. The analytical performance was evaluated based on the sigma, sigma > 6 is world class, sigma > 5 is excellent, sigma > 4 is good and sigma < 4 is satisfactory and sigma < 3 is poor performance. Results: Based on the calculation, we found that, 96% are world class (ALT, albumin, ALP, amylase, AST, total bilirubin, cholesterol, HDL-cholesterol, creatinine, creatinine kinase, glucose, LDH, magnesium, potassium, triglyceride and uric acid. 14% are excellent (calcium, protein and urea), and 10% ( chloride and sodium) require more frequent IQC performed per day. Conclusion: Based on this study, we found that IQC should be performed frequently for only Chloride and Sodium to ensure accurate and reliable analysis for patient management.

Keywords: sigma matrics, analytical performance, total error, bias

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Authors: Parvathy Anitha, Nilesh J. Vasa, M. S. Ramachandra Rao

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ZnO is a semiconducting material with a direct wide band gap of 3.37 eV and a large exciton binding energy of 60 meV at room temperature. Microspheres with high sphericity and symmetry exhibit unique functionalities which makes them excellent omnidirectional optical resonators. Hence there is an advent interest in fabrication of single crystalline semiconductor microspheres especially magnetic ZnO microspheres, as ZnO is a promising material for semiconductor device applications. Also, ZnO is non-toxic and biocompatible, implying it is a potential material for biomedical applications. Room temperature Photoluminescence (PL) spectra of the fabricated ZnO microspheres were measured, at an excitation wavelength of 325 nm. The ultraviolet (UV) luminescence observed is attributed to the room-temperature free exciton related near-band-edge (NBE) emission in ZnO. Besides the NBE luminescence, weak and broad visible luminescence (~560nm) was also observed. This broad emission band in the visible range is associated with oxygen vacancies related to structural defects. In transition metal (TM) ion-doped ZnO, 3d levels emissions of TM ions will modify the inherent characteristic emissions of ZnO. A micron-sized ZnO crystal has generally a wurtzite structure with a natural hexagonal cross section, which will serve as a WGM (whispering gallery mode) lasing micro cavity due to its high refractive index (~2.2). But hexagonal cavities suffers more optical loss at their corners in comparison to spherical structures; hence spheres may be a better candidate to achieve effective light confinement. In our study, highly smooth spherical shaped micro particles with different diameters ranging from ~4 to 6 μm were grown on different substrates. SEM (Scanning Electron Microscopy) and AFM (Atomic Force Microscopy) images show the presence of uniform smooth surfaced spheres. Raman scattering measurements from the fabricated samples at 488 nm light excitation provide convincing supports for the wurtzite structure of the prepared ZnO microspheres. WGM lasing studies from TM-doped ZnO microparticles are in progress.

Keywords: laser ablation, microcavity, photoluminescence, ZnO microsphere

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Authors: Chang Yu Chuan

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Background and Aim: Pressure sore is not only the consequence of any gradual damage of the skin leading to tissue defects but also an important indicator of clinical care. If hospitalized patients develop pressure sores without proper care, it would result in delayed healing, wound infection, increase patient physical pain, prolonged hospital stay and even death, which would have a negative impact on the quality of care and also increase nursing manpower and medical costs. This project is aimed at decreasing the incidence of pressure sore in one ward of internal medicine. Our data showed 53 cases (0.61%) of pressure sore in 2015, which exceeded the average (0.5%) of Taiwan Clinical Performance Indicator (TCPI) for medical centers. The purpose of this project is to reduce the incidence rate of pressure sore in the ward. After data collection and analysis from January to December 2016, the reasons of developing pressure sore were found: 1. Lack of knowledge to prevent pressure among nursing staffs; 2. No relevant courses about preventing pressure ulcers and pressure wound care being held in this unit; 3. Low complete rate of pressure sore care education that family members should receive from nursing staffs; 4. Decompression equipment is not enough; 5. Lack of standard procedures for body-turning and positioning care. After team members brainstorming, several strategies were proposed, including holding in-service education, pressure sore care seed training, purchasing decompression mattress and memory pillows, designing more elements of health education tools, such as health education pamphlet, posters and multimedia films of body-turning and positioning demonstration, formulation and promotion of standard operating procedures. In this way, nursing staffs can understand the body-turning and positioning guidelines for pressure sore prevention and enhance the quality of care. After the implementation of this project, the pressure sore density significantly decreased from 0.61%(53 cases) to 0.45%(28 cases) in this ward. The project shows good results and good example for nurses working at the ward and helps to enhance quality of care.

Keywords: body-turning and positioning, incidence density, nursing, pressure sore

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Authors: Tomasz Dubiel, Tadeusz Balawender, Miroslaw Osetek

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The paper presents the influence of non-metallic inclusions on the multi-stage forging process and the mechanical properties of the dodecagon socket bolt used in the automotive industry. The detected metallurgical defect was so large that it directly influenced the mechanical properties of the bolt and resulted in failure to meet the requirements of the mechanical property class. In order to assess the defect, an X-ray examination and metallographic examination of the defective bolt were performed, showing exogenous non-metallic inclusion. The size of the defect on the cross-section was 0.531 [mm] in width and 1.523 [mm] in length; the defect was continuous along the entire axis of the bolt. In analysis, a FEM simulation of the multi-stage forging process was designed, taking into account a non-metallic inclusion parallel to the sample axis, reflecting the studied case. The process of defect propagation due to material upset in the head area was analyzed. The final forging stage in shaping the dodecagonal socket and filling the flange area was particularly studied. The effect of the defect was observed to significantly reduce the effective cross-section as a result of the expansion of the defect perpendicular to the axis of the bolt. The mechanical properties of products with and without the defect were analyzed. In the first step, the hardness test confirmed that the required value for the mechanical class 8.8 of both bolt types was obtained. In the second step, the bolts were subjected to a static tensile test. The bolts without the defect gave a positive result, while all 10 bolts with the defect gave a negative result, achieving a tensile strength below the requirements. Tensile strength tests were confirmed by metallographic tests and FEM simulation with perpendicular inclusion spread in the area of the head. The bolts were damaged directly under the bolt head, which is inconsistent with the requirements of ISO 898-1. It has been shown that non-metallic inclusions with orientation in accordance with the axis of the bolt can directly cause loss of functionality and these defects should be detected even before assembling in the machine element.

Keywords: continuous casting, multi-stage forging, non-metallic inclusion, upset bolt head

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Authors: Yi-Hao Pai, Wen-Feng Chen

Abstract:

The planting area of Pomelo in Hualien, Taiwan amounts to thousands of hectares. Especially in the blooming season of Pomelo, it is an important producing area for Pomelo honey, and it is also a good test field for promoting the "Under-forest Economy". However, in the current Pomelo garden planting and management operations, the large amount of agricultural waste generated by the pruning of the branches causes environmental sanitation concerns, which can lead to the hiding of pests or the infection of the Pomelo tree, and indirectly increase the health risks of bees. Therefore, how to deal with the pruning of the branches and avoid open burning is a topic of social concern in recent years. In this research, afeasibility study evaluating energy conversion efficiency through agricultural waste gasification from the Pomelo garden, Taiwan, is demonstrated. we used a high-temperature gasifier to convert the pruning of the branches into syngas and biochar. In terms of syngas composition and calorific value assessment, we use the biogas monitoring system for analysis. Then, we used Raman spectroscopy and electron microscopy (EM) to diagnose the microstructure and surface morphology of biochar. The results indicate that the 1 ton of pruning of the branches can produce 1797.03m3 of syngas, corresponding to a calorific value of 9.1MJ/m3. The main components of the gas include CH4, H2, CO, and CO2, and the corresponding gas composition ratio is 16.8%, 7.1%, 13.7%, and 24.5%. Through the biomass syngas generator with a conversion efficiency of 30% for power generation, a total of 1,358kWh can be obtained per ton of pruning of the branches. In the research of biochar, its main characteristics in Raman spectroscopy are G bands and D bands. The first-order G and D bands are at 1580 and 1350 cm⁻¹, respectively. The G bands originates from the in-plane tangential stretching of the C−C bonds in the graphitic structure, and theD band corresponds to scattering from local defects or disorders present in carbon. The area ratio of D and G peaks (D/G) increases with the decrease of reaction temperature. The larger the D/G, the higher the defect concentration and the higher the porosity. This result is consistent with the microstructure displayed by SEM. The study is expected to be able to reuse agricultural waste and promote the development of agricultural and green energy circular economy.

Keywords: agricultural waste, gasification, energy conversion, pomelo garden

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Authors: Abdullah Alnutayfat, Alexander Sutin, Dong Liu

Abstract:

Wind turbine has become one of the most popular energy productions. However, failure of blades and maintenance costs evolve into significant issues in the wind power industry, so it is essential to detect the initial blade defects to avoid the collapse of the blades and structure. This paper aims to apply modulation of high-frequency blade vibrations by low-frequency blade rotation, which is close to the known Vibro-Acoustic Modulation (VAM) method. The high-frequency wideband blade vibration is produced by the interaction of the surface blades with the environment air turbulence, and the low-frequency modulation is produced by alternating bending stress due to gravity. The low-frequency load of rotational wind turbine blades ranges between 0.2-0.4 Hz and can reach up to 2 Hz for strong wind. The main difference between this study and previous ones on VAM methods is the use of a wideband vibration signal from the blade's natural vibrations. Different features of the vibroacoustic modulation are considered using a simple model of breathing crack. This model considers the simple mechanical oscillator, where the parameters of the oscillator are varied due to low-frequency blade rotation. During the blade's operation, the internal stress caused by the weight of the blade modifies the crack's elasticity and damping. The laboratory experiment using steel samples demonstrates the possibility of VAM using a probe wideband noise signal. A cycle load with a small amplitude was used as a pump wave to damage the tested sample, and a small transducer generated a wideband probe wave. The received signal demodulation was conducted using the Detecting of Envelope Modulation on Noise (DEMON) approach. In addition, the experimental results were compared with the modulation index (MI) technique regarding the harmonic pump wave. The wideband and traditional VAM methods demonstrated similar sensitivity for earlier detection of invisible cracks. Importantly, employing a wideband probe signal with the DEMON approach speeds up and simplifies testing since it eliminates the need to conduct tests repeatedly for various harmonic probe frequencies and to adjust the probe frequency.

Keywords: vibro-acoustic modulation, detecting of envelope modulation on noise, damage, turbine blades

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