High performance of silicone rubber nanocomposites with improved physical properties

Highly extent exfoliated and intercalated silicone rubber (SR) nanocomposites based on natural montmorillonite (Cloisite Na+) and organically modified montmorillonite (Cloisite 30B and Cloisite 20A) were successfully prepared by melt-mixing technique. As indicated by the X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis, intercalation and exfoliation of the clay particles in the nanocomposites was achieved at less than 8 parts per hundred (phr) rubber by weight, irrespective of the initial interlayer spacing of the nanoclay particles. Cloisite 30B was spontaneously transformed into exfoliated nanostructures during the vulcanisation stage as suggested by X-ray diffraction (XRD), fourier transforms infra-red spectroscopy (FTIR) and differential scanning calorimeter (DSC) results. [Continues.

Seroprevalence of bovine anaplasmosis caused by Anaplasma marginale in Malaysia

Anaplasmosis, also known as yellow fever, is an infectious parasitic disease of cattle caused by the protozoan Anaplasma marginale. Anaplasma marginale infects the erythrocytes and causes severe anaemia, weakness, loss of appetite, fever, depression, abortion, decreased milk production, constipation, jaundice and sometimes death. In Malaysia, data on A. marginale infection is still behind compared to other parasites such as nematodes. Anaplasmosis in livestock has received little attention in Malaysia with only occasional reports in cattle. In addition, the determinants of tick- and fly-borne transmission are not well understood. Looking into this possibility, this study was carried out to investigate and to compare the prevalence rate of bovine anaplasmosis in Malaysia. A seroprevalence study on bovine anaplasmosis was conducted at the Veterinary Research Institute, Malaysia. Sera of various cattle breeds were collected from farms and abattoirs to be tested for the presence of A. marginale. Competitive enzyme-linked immunosorbent assay (c-ELISA) Anaplasma antibody test kits by VMRD, Inc. were used for this study, where antibodies to A. marginale from sample sera inhibit the binding of horseradish peroxidase (HRP)-labelled monoclonal antibody to the Anaplasma antigen coated on the plastic wells. A total number of 267 serum samples were tested and 79.4% were positive for bovine anaplasmosis. Results showed that the infection percentage is 100% in Pahang while the state with lowest infection percentage is Sabah with 59.2%. A comparison is done between Peninsular Malaysia with Sabah and Sarawak. The infection percentage in Peninsular Malaysia is higher at 87% while Sabah and Sarawak has an infection percentage of 60%. However, there is no significant difference in the rate of infections. The high number of cases in Peninsular Malaysia may be caused by the lack of strict control measures due to dependence on modern tools and drugs, while cases in Sabah and Sarawak may be due to traditional practices carried out frequently that may cause iatrogenic transmission. More samples should be obtained in order to validate the results. In addition, annual studies must be done to monitor the status of A. marginale prevalence in local cattle that is medically and economically significant to Malaysia

Improving heat ageing and thermal properties of silicone rubber using montmorillonite clay

Heat ageing and thermal stability of a silicone rubber (SR) filled with montmorillonite clay (MMT) was investigated. Three types of rubber nanocomposites were prepared with hig hly exfoliated Cloisite 30B (SR/C30B), intercalated/exfoliated Cloisite Na 1 (SR/Na 1 MMT), and highly intercalated Cloisite 20A (SR/C20A). This study showed that the SR/C30B nanocomposite exhibited excellent heat resistance in comparison to the other two nanocomposites and neat SR as revealed by higher retention strength. The thermal stability of the rubber in air was strongly dependent on the clay morphology and increased in the following order: highly intercalated/exfoliated SR/Na 1 MMT < highly intercalated SR/C20A < highly exfoliated SR/C30B. The thermogravimetric analyses of the SR/C30B nanocomposite showed a substantial increase in the final residue in comparison with the neat SR. This indicated a major improvement in the thermal stability of the rubber containing the exfoliated clay, which was also supported by the higher activation energy of decomposition measured for the nanocomposite

Effect of hybrid reinforcement based on precipitated silica and montmorillonite nanofillers on the mechanical properties of a silicone rubber

Silicone rubber (SR) nanocomposites containing precipitated silica (PS), montmorillonite (MMT) and PS/MMT hybrid fillers were prepared through melt-mixing technique. In the SR/PS/MMT nanocomposite, the hybrid filler weight ratio was increased progressively from 0.4 to 1.7 while keeping the MMT weight constant. The viscosity, cure characteristics and mechanical properties of the nanocomposites were subsequently measured. The optimum cure time increased and the scorch time and rate of cure decreased. Furthermore, when the hybrid filler weight ratio was raised to its optimum, the tensile strength, Young’s modulus, modulus at 100% and 300% elongation (M100 and M300), elongation at break, stored energy density at break and hardness of the nanocomposite improved. The stress-strain properties of the nanocomposite with the hybrid filler improved at high deformation in comparison with those containing the PS and MMT fillers. The MMT filler exfoliated in the SR/MMT nanocomposite but did not in the nanocomposites containing the hybrid filler. Notably, the mechanical properties of the nanocomposite benefitted from the hybrid filler. This was due to the filler-filler and filler-rubber network formation in the rubber by the PS particles. Finally, effect of the PS, MMT and hybrid fillers on the energy loss or hysteresis of the rubber was measured

Preparation and characterization of high performance exfoliated montmorillonite/silicone rubber nanocomposites with enhanced mechanical properties

Highly exfoliated and intercalated silicone rubber (SR) nanocomposites based on natural montmorillonite (Cloisite Na+) and organically modified montmorillonite (Cloisite 30B and Cloisite 20A) were successfully prepared by melt-mixing technique. Dispersion of the nanoclays in the rubber nanocomposites was subsequently investigated. As indicated by the X-ray diffraction (XRD) analysis, intercalation and exfoliation of the clay particles in the nanocomposites was achieved at less than 8 parts per hundred (phr) rubber by weight, irrespective of the initial interlayer spacing of the nanoclay particles. Both Cloisite Na+ and Cloisite 30B were spontaneously transformed into exfoliated microstructures during the vulcanisation stage. Overall, the use of the nanoclays in silicone rubber improved the Young’s modulus, tensile strength and elongation at break by more than 50% as compared to the control rubber. In addition, this work provided a fresh insight into the way intercalated and exfoliated morphologies affect mechanical properties of silicone rubber nanocomposites. It was shown that the exfoliated Cloisite Na+ yielded outstanding mechanical properties with low hysteresis at the same loading of the exfoliated Cloisite 30B and intercalated Cloisite 20A organoclays. As expected, the formation of crosslinks affected the mechanical properties of the rubber vulcanizate significantly

Psychiatric disorders among young male adult prisoners: a cross sectional study in a Malaysian prison

Introduction: In recent years there has been an increase in the number of young people in prison. This study is the firstto look at the proportion of psychiatric disorders among young adultprisoners. Objective: The main objective is to determine the percentage of psychiatric disorders among young adult male prisoners. Method: A cross sectional study of young adult male prisoners, with ages ranged between 18 and 21 years old, was conducted between September and December, 2008 at the Kajang Prison. A total of 225 inmates participated in the study which used the Mini International Neuropsychiatric Interview (MINI) as its instrument. Results: The percentage of psychiatric disorders was 60.0%. Alcohol and substance related disorders had the highest prevalence at 50.2%, followed by Major Depressive Disorders and Dysthymia at 16.9%. About 39.6% were observed to have antisocial personality disordet Psychiatric disorders were found to have significant differences (p<O.05) in connection with parental marriage and recidivism. Conclusion: This study shows that the percentage of psychiatric disorders, especially substance related disorders, is high among young male adult prisoners. It highlights the urgent need for early intervention for this group of young people

Mixed method for the product integral on the infinite interval

In this note, quadrature formula is constructed for product integral on the infinite interval I(f) = ∫ w(x)f(x)dx, where w(x) is a weight function and f(x) is a smooth decaying function for x > N (large enough) and piecewise discontinuous function of the first kind on the interval a ≤ x ≤ N. For the approximate method we have reduced infinite interval x [a, ∞) into the interval t[0,1] and used the mixed method: Cubic Newton’s divided difference formula on [0, t3) and Romberg method on [t3,1] with equal step size, ti = t0+ih,i=0, …,n, h=1/n, where t0 = 0,tn=1. Error term is obtained for mixed method on different classes of functions. Finally, numerical examples are presented to validate the method presented

A Pilot Study on the Quality of Life in Family Caregivers of Cancer Patients at an Urban Tertiary Hospital in Kuala Lumpur

Background: Family plays an important role in caregiving of cancer patients. There are limited published articles on cancer caregiving in the Malaysian population. The aim of the study was to determine the quality of life (QoL) of cancer patient caregivers and its associated factors. Subjects and Method: A cross-sectional study was conducted at an urban tertiary hospital in Kuala Lumpur, Malaysia. A total of 94 family caregivers of all types of cancer patients completed validated questionnaires in the national language. The dependent variable was theQoL in family caregivers, which was measured by the Malay Caregiver Quality of Life–Cancer (MCQOL-C) questionnaire. It consisted of 35 items, and the domains are burden, positive adaptation, disruptiveness, financial concerns and others. The higher the QoL scores, the better the QoL. The independent variables were socio-demographic factors (age, education level, ethnicity, gender, marital status, relationship with patient, any children less than 18 years old, and employment status). The data were analyzed by a linear regression model. Results: The study population (N= 94) comprised of 73.4% females, 38.8% were spouses to cancer patients. The mean age was 45.02+14.65, ranged from 17-78 years old. Half (56.4%) of the study subjects were Malays, 54.3% obtained secondary education, and 50% were not working. The reliability of the questionnaire was good with Cronbach alpha= 0.87. The mean (SD) score of QoL was 80.57 (21.27), ranged from 25-128. The multivariate analysis showed that being non-Malay had lower quality of life than Malay (b= -18.40; 95% CI= 3.10 to 33.70; p= 0.020). Conclusion: Ethnicity affects the QoL of cancer patient caregiving. This provides invaluable insight for developing health care service. Keywords: quality of life, family caregiver, cance

Complete curvature homogeneous pseudo-Riemannian manifolds

We exhibit 3 families of complete curvature homogeneous pseudo-Riemannian manifolds which are modeled on irreducible symmetric spaces and which are not locally homogeneous. All of the manifolds have nilpotent Jacobi operators; some of the manifolds are, in addition, Jordan Osserman and Jordan Ivanov-Petrova.Comment: Update paper to fix misprints in original versio

The concept of murabbi in Muslim education with reference to selected teaching methods of the prophet Muhammad (ٍٍٍِSAW)

The concept of education in Islam is markedly different from that seen from the secular Western viewpoint. For Muslims, teaching is considered as the noblest of professions, while the Prophet Muhammad (SAW) is known as the greatest educator of all time. The focus of this paper is to explore the meaning of the concept of murabbī (Muslim educator) and then to consider selected pedagogical practices of the Prophet Muhammad (SAW) which were used to educate the early Muslim community. It is hoped that the pragmatic and spiritual nature of his pedagogical practices will serve as an inspiration and role model for Muslim and non-Muslim teachers and educators today and in the future, inshallah