Theoretical Aspects of some Mechanical Properties of Composites

In the present wok, two mathematical models are constructed in orderto define the detailed nature of composite. The first one is based on theclassical Rule of Mixtures, (RoM) which is normally rotted from the ordinarystrength of materials. The second model is based on the theory of elasticity,which deals with the detailed response of the internal macrostructure of thecomposite. A virtual composite was assumed to be formed of a number ofmatrices (Epoxy resin & Nickel) containing various inclusions (Carbon fibres& powder, E-glass fibres & powder, and Kevlar fibres) in sequentialpermutations. In general, the elasticity model E, exhibited various degrees ofsuperiority to the RoM depending on the mechanical parameters in questionand the mechanism by which it influences the internal details of the material

Oral health knowledge and behavior among male health sciences college students in Kuwait

BACKGROUND: Health auxiliary personnel have an important role in oral health promotion when they graduate and start working in the health care system. This study aims to find out oral health knowledge and oral health behavior of male Health Sciences College students. METHODS: A questionnaire was distributed to all students at the male Health Sciences College in Kuwait (N = 153) during the academic year 2001/2002. The students filled the anonymous questionnaire in the class after the lecture. The response rate was 84% (n = 128). The questions consisted information on the general background, oral health behavior and oral health knowledge. RESULTS: Oral health knowledge seemed to be limited and very few background factors were associated with it. More than half of the students had visited a dentist during the previous 12 months, but only one third of students were brushing twice a day or more often. CONCLUSIONS: It may be concluded that the male Health Sciences College students seemed to have appropriate knowledge on some oral health topics, but limited knowledge on the others. Their toothbrushing practices are still far behind the international recommendation (twice a day) and also the knowledge, why it should be done so frequently also very limited

Silicone Oil Utilized in Pars Plana Vitrectomy for Patients with Advanced Proliferative Diabetic Retinopathy: Physico-Chemical and Optical Properties

Rami Al-Dwairi,1 Ahmad A Ahmad,2 Abdelwahab Aleshawi,1 Areen A Bani-Salameh,2 Ihsan A Aljarrah,2 Qais M Al-Bataineh,2,3 Seren Al Beiruti,1 Ali Omar Alshami,1 Edina Rusen,4 Gabriela Toader5 1Department of Special Surgery, Division of Ophthalmology, Faculty of Medicine, Jordan University of Science & Technology, Irbid, 22110, Jordan; 2Department of Physics, Thin Films and Nanotechnology Laboratory, Faculty of Science and Art, Jordan University of Science & Technology, Irbid, 22110, Jordan; 3Leibniz Institut für Analytische Wissenschaften‐ISAS‐e.V., Dortmund, 44139, Germany; 4Faculty of Chemical Engineering and Biotechnologies, University POLITEHNICA of Bucharest, Bucharest, 011061, Romania; 5Military Technical Academy “Ferdinand I”, Bucharest, 050141, RomaniaCorrespondence: Rami Al-Dwairi, Department of Special Surgery, Division of Ophthalmology, Faculty of Medicine, Jordan University of Science & Technology, P. O. Box: 3030, Irbid, 22110, Jordan, Tel +962799273019, Fax +962 2 7201064, Email [email protected]: Silicone oils have the role in maintaining the attachment of the retina in conditions where the risk of retinal re-detachment is high. However, silicone oils have the tendency to emulsify with subsequent complications. In this work, analyses have been performed to understand changes that occurred to the optical, and physical characteristics of the oil after removal from the vitreous cavity of patients underwent pars plana vitrectomy (PPV) for fibrovascular membranes/tractional retinal detachment (FVM/TRD).Methods: Four samples of silicone oil were allocated from patients who underwent PPV for FVM/TRD. The Fourier-transform infrared (FTIR) spectroscopy, micro-viscometry, and ultraviolet-visible spectrometer analyses were utilized to determine the changes in its chemical bondings, viscosity, absorbance, transmittance, buoyance, and specific gravity.Results: The mean age of the patients was 49.0 years. The mean duration of silicone oil implantation was 18.9 months. FTIR analysis showed significant breaking in the chemical bonding that was related to the lens status during the primary PPV, the presence of significant retinal hemorrhages, the duration of silicone oil implantation, and the degree of silicone oil filling. Similarly, viscosity and contact angle analyses revealed a reduction in the viscosity with similar factors to the FTIR analysis. Moreover, absorbance and transmittance were largely affected by the aggressiveness of FVM/TRD.Conclusion: This study revealed that certain factors such as the age of the patient, duration of silicone oil implantation, lens status, and the presence of retinal hemorrhages, the degree of silicone oil filling and aggressiveness of FVM/TRD may contribute to the emulsification process.Keywords: silicone oil, tractional retinal detachment, emulsification, viscosit