Surface finish effect on dry sliding wear behavior of thermally oxidized commercially pure zirconium

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.The aim of this work was to investigate the effect of surface polishing on the wear behavior of thermally oxidized commercial pure zirconium (CP-Zr) under dry sliding conditions. Surface ground CP-Zr with a roughness of 0.21 m (Ra) was thermally oxidized (TO) at 650 °C for 6 h. After TO, some samples were polished to smoothen the surface with a finish of 0.04 m (Ra). The response of the polished and unpolished TO samples to dry sliding wear was investigated under unidirectional sliding conditions. The results show that surface polishing after TO affects the dry sliding wear behavior of TO CP-Zr in several aspects, including coefficient of friction, wear rate, crack formation and oxide layer breakdown. In particular, it is found that smoothening the TO surface favors the formation of semi-circular cracks in the wear track and accelerates oxide layer breakdown during dry sliding. A slightly rough TO surface helps to reduce the tendency of the oxide layer towards cracking and to increase the wear resistance at high contact loads. The mechanisms involved are discussed in terms of asperity contacts, crack formation, propagation and final fracture

A comparative study of the mechanical behaviour of thermally oxidized commercially pure titanium and zirconium

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.The objective of this study is to compare the mechanical behaviour of thermally oxidised commercially pure titanium (CP-Ti) and commercially pure zirconium (CP-Zr). For this purpose, these two bio-metals were thermally oxidised under the same condition (650 °C for 6 h) and the oxidised specimens were characterised using various analytical and experimental techniques, including oxygen uptake analysis, layer thickness and hardness measurements, scratch tests, dry sliding friction and wear tests and tribocorrosion tests in Ringer’s solution. The results show that under the present thermal oxidation condition, 4 times more oxygen is introduced into CP-Zr than into CP-Ti and the oxide layer produced on CP-Zr is nearly 6 times thicker than that on CP-Ti. Thermally oxidised CP-Zr possesses a higher hardness, a deeper hardening depth and better scratch resistance than thermally oxidised CP-Ti. Under dry sliding and tribocorrosion conditions, thermally oxidised CP-Zr also possesses much better resistance to material removal and a higher load bearing capacity than thermally oxidised CP-Ti. Thus, thermally oxidised Zr possesses much better mechanical behaviour than thermally oxidised Ti

Effect of oxidation time on the tribological behavior of thermally oxidized commercially pure zirconium under dry sliding conditions

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Thermal oxidation is an effective surface engineering technique to harden the surfaces of zirconium (Zr) and its alloys for improvement in friction and wear performance. In the present investigation, commercially pure zirconium (CP-Zr) is oxidized at 650 °C for a wide range of times from 1 h to 72 h with the aim to study the effect of oxidation time on the tribological performance of CP-Zr. It is found that a dense, pore-free and adherent zirconium dioxide (ZrO2) layer can be produced at the surface for oxidation times less than 12 h. Further increasing oxidation time leads to the gradual development of pores in the inner part of the oxide layer and oxidation breakaway characterized by accelerated oxidation kinetics and crack formation. Oxidation time has a significant effect on the tribological behaviour of thermally oxidized CP-Zr under dry sliding conditions. The 6 m thick oxide layer produced by 6 h treatment possesses the lowest friction, best wear resistance and the highest load bearing capacity. On the other hand, the thicker oxide layers produced by longer treatment times show deteriorated tribological behavior. The results are discussed in terms of the morphology of the oxide layer and crack propagation in the oxide layer and the underlying diffusion zone

Inclusion of Students with Special Needs in Private Schools in Kuwait: Challenges that Face School Administrators

The inclusion approach is one of the most effective ways of integrating students with special needs into society. According to Kuwaiti regulations, both public and private schools must increase quality services to assist students with special needs in inclusive classrooms. Although the inclusion approach is mandatory in Kuwait, schools have encountered barriers to its implementation. Therefore, there were three key goals to this research: (a) to identify challenges of the implementation of inclusion approaches that face private primary school administrators in Kuwait, (b) to identify how inclusion practices are implemented by administrators, teachers, and counselors in private Kuwaiti primary schools, and (c) to identify the differences in the implementation practices of inclusion between two private primary schools in Kuwait. The findings revealed that the two schools faced six similar challenges, and three that differed. The obstacles the two schools had in common included: (1) parental issues, (2) academic barriers, (3) a lack of specialist teachers, (4) gaps in communication, (5) modification and accommodation matters, and (6) financial issues. The three that differed for the first school were: (1) low expectations, (2) the large number of students with LD, and (3) policy issues, while for the second school they were: (1) time management, (2) disciplinary issues, (3) systemic problems. Six key methods for implementing the inclusion approach were revealed. Four were common to both schools and two were different. The four in common were: (1) learning styles, (2) collaboration, (3) communication, and (4) preparation. The two seen solely in the first school were: (1) cooperative learning among students, and (2) discipline management, and in the second school they were (1) teaching LD students in small groups, and (2) anti-bullying sessions. Based on the findings of this research, future work should examine the challenges faced by school administrators attempting to implement the inclusion process, especially at the high school and university levels

Inclusion of Students with Special Needs in Private Schools in Kuwait: Challenges that Face School Administrators

The inclusion approach is one of the most effective ways of integrating students with special needs into society. According to Kuwaiti regulations, both public and private schools must increase quality services to assist students with special needs in inclusive classrooms. Although the inclusion approach is mandatory in Kuwait, schools have encountered barriers to its implementation. Therefore, there were three key goals to this research: (a) to identify challenges of the implementation of inclusion approaches that face private primary school administrators in Kuwait, (b) to identify how inclusion practices are implemented by administrators, teachers, and counselors in private Kuwaiti primary schools, and (c) to identify the differences in the implementation practices of inclusion between two private primary schools in Kuwait. The findings revealed that the two schools faced six similar challenges, and three that differed. The obstacles the two schools had in common included: (1) parental issues, (2) academic barriers, (3) a lack of specialist teachers, (4) gaps in communication, (5) modification and accommodation matters, and (6) financial issues. The three that differed for the first school were: (1) low expectations, (2) the large number of students with LD, and (3) policy issues, while for the second school they were: (1) time management, (2) disciplinary issues, (3) systemic problems. Six key methods for implementing the inclusion approach were revealed. Four were common to both schools and two were different. The four in common were: (1) learning styles, (2) collaboration, (3) communication, and (4) preparation. The two seen solely in the first school were: (1) cooperative learning among students, and (2) discipline management, and in the second school they were (1) teaching LD students in small groups, and (2) anti-bullying sessions. Based on the findings of this research, future work should examine the challenges faced by school administrators attempting to implement the inclusion process, especially at the high school and university levels

Current status of tissue engineering in the management of severe hypospadias

Hypospadias, characterized by misplacement of the urinary meatus in the lower side of the penis, is a frequent birth defect in male children. Because of the huge variation in the anatomic presentation of hypospadias, no single urethroplasty procedure is suitable for all situations. Hence, many surgical techniques have emerged to address the shortage of tissues required to bridge the gap in the urethra particularly in the severe forms of hypospadias. However, the rate of postoperative complications of currently available surgical procedures reaches up to one-fourth of the patients having severe hypospadias. Moreover, these urethroplasty techniques are technically demanding and require considerable surgical experience. These limitations have fueled the development of novel tissue engineering techniques that aim to simplify the surgical procedures and to reduce the rate of complications. Several types of biomaterials have been considered for urethral repair, including synthetic and natural polymers, which in some cases have been seeded with cells prior to implantation. These methods have been tested in preclinical and clinical studies, with variable degrees of success. This review describes the different urethral tissue engineering methodologies, with focus on the approaches used for the treatment of hypospadias. At present, despite many significant advances, the search for a suitable tissue engineering approach for use in routine clinical applications continues. 2018 Abbas, Mahdi, Hasan, AlAnsari and Pennisi.Scopu

Development of a novel 3D gut-microbiota model for the assessment of absorption and metabolism of health supplements and therapeutic drugs

The human body hosts a vast number of microorganisms such as bacteria, archaea, and viruses that are colonised inside and outside the body. This combination of microorganisms living within the human body is known as microbiota. The human microbiota varies depending on the anatomical site such as the skin, the respiratory tract, the gastrointestinal tract, and the genitourinary tract. Microbiota’s composition and function can also vary according to the age, sex, race, and diet of its host. This research focuses on the microbiota present in the gastrointestinal tract and how it can affect the absorption of molecules. By using two types of epithelial cell lines, Caco-2 and HT29-MTX and a bacterial strain, lactobacillus bacteria. To upgrade the existing Caco-2 model. The cells were cultured in specialised plates until differentiation. Erythromycin, vitamin D3, and linoleic acid were used as test compounds. TEER and Lucifer yellow were used to monitor the integrity and formation of the monolayer. Absorption of the three molecules were studied by mass spectrometry. The results indicated that the combination of cells and bacteria produced similar results to the ADMETox model currently in use the pharmaceutical industry

Renoprotective effect of red grape (Vitis vinifera L.) juice and dark raisins against hypercholesterolaemia-induced tubular renal affection in albino rats

Background: Red grape juice (RGJ) and dark raisins (DR) are rich in polyphenols and antioxidants. This study aimed to assess the efficacy of RGJ and DR in protec- ting the renal tubules against hypercholesteraemic-induced pathological changes.  Materials and methods: Forty albino rats divided into four groups (n = 10) were utilised in this study. They included the control, high cholesterol diet (HCD)-fed, HCD+RGJ-fed, and HCD+DR-fed groups. Body weight gain, food and water in- take, blood and insulin levels, lipid profile and kidney functions were assessed at the start of the experiment and after 12 weeks. The right kidney was dissected out and processed for both light and electron microscopic examination. Desmin and cytokeratin antibodies were utilised as histologic markers to assess the integrity of the proximal (PTs) and distal tubules (DTs) of the kidney.  Results: Administration of HCD resulted in hypercholesterolaemia in rats as evi- denced by the lipid profile. The PTs of hypercholesteraemic rats appeared dilated with hyaline casts and mitochondria in most of the tubular cells were affected. Immunohistochemical assessment revealed affection of both PTs and DTs. Both RGJ and DR, when administered along with the HCD for 12 weeks, improved the lipid profile, kidney functions as well as the histologic and cellular changes-induced by hypercholesterolaemia in the rats. The effect of raisins was superior to RGJ which might be due to its high contents of fibres and proteins.  Conclusions: This study highlighted the importance of supplementation of red grape and raisins in protection against the harmful effects induced by deposition of fat on the renal tubules’ structure and function.

Unique Presentation of Intra-Abdominal Testis: Small Bowel Obstruction

We describe here a two-year-old male who required urgent laparotomy to relieve a strangulated small bowel caused by internal herniation around an intra-abdominal testis. This clinical presentation has not been reported previously