Bamboo-Fiber-Reinforced Thermoset and Thermoplastic Polymer Composites: A Review of Properties, Fabrication, and Potential Applications.

Natural-fiber-reinforced composites, especially bamboo, are an alternative material to compete with conventional materials. Their environmentally friendly, renewable, low-cost, low-density, non-toxic, and fully biodegradable properties are concerning for researchers because of their advantages over synthetic polymers. This comprehensive review presents the results of work on bamboo fiber composites with special reference to bamboo types, thermoplastic and thermoset polymers matrices, hybrid composites, and their applications. In addition, several studies prove that these properties are very good and efficient in various applications. However, in the development of composite technology, bamboo fiber has certain constraints, especially in moisture conditions. Moisture is one of the factors that reduces the potential of bamboo fiber and makes it a critical issue in the manufacturing industry. Therefore, various efforts have been made to ensure that these properties are not affected by moisture by treating the surface fibers using chemical treatments.

Effect of Silver Nanopowder on Mechanical, Thermal and Antimicrobial Properties of Kenaf/HDPE Composites.

This study aims to investigate the effect of AgNPs on the mechanical, thermal and antimicrobial activity of kenaf/HDPE composites. AgNP material was prepared at different contents, from 0, 2, 4, 6, 8 to 10 wt%, by an internal mixer and hot compression at a temperature of 150 °C. Mechanical (tensile, modulus and elongation at break), thermal (TGA and DSC) and antimicrobial tests were performed to analyze behavior and inhibitory effects. The obtained results indicate that the effect of AgNP content displays improved tensile and modulus properties, as well as thermal and antimicrobial properties. The highest tensile stress is 5.07 MPa and was obtained at 10wt, TGA showed 10 wt% and had improved thermal stability and DSC showed improved stability with increased AgNP content. The findings of this study show the potential of incorporating AgNP concentrations as a secondary substitute to improve the performance in terms of mechanical, thermal and antimicrobial properties without treatment. The addition of AgNP content in polymer composite can be used as a secondary filler to improve the properties.

The effects of angiotensin-converting enzyme gene polymorphism on the progression of immunoglobulin A nephropathy in Malaysian patients.

INTRODUCTION: Angiotensin-converting enzyme (ACE) gene polymorphism, especially the deletion/deletion (DD) genotype, is associated with the disease progression of immunoglobulin A (IgA) nephropathy patients in various studies from both Asia Pacific and European populations. However, recent studies within the same populations were unable to reproduce the same results. Hence, we had studied the distribution of the DD genotype, the association between ACE gene polymorphism and the disease progression, and the factors (other than ACE gene polymorphism) which were involved in the disease progression of our local patients. METHODS: This was a cross-sectional study of biopsy-proven IgA nephropathy patients attending the Nephrology Clinic, Hospital Universiti Kebangsaan Malaysia. Both biochemical and urine tests at the time of first presentation were compared to those at the time of the study, and the disease progression was analysed. The ACE gene polymorphism was identified via PCR-amplification technique, and patients were then categorised into the DD and the non-DD groups for detailed analysis. Histological severity of each renal biopsy was scored according to the predetermined criteria and medications used were recorded. The association between the gene polymorphism and disease progression was then determined. The patients who were stable or had renal function deterioration, were respectively regrouped into Groups 1 and 2, to identity those factors (other than ACE gene polymorphism), which were involved in the disease progression. RESULTS: 60 patients with adequate renal histopathological examination were recruited. Their mean age was 40.9 +/- 12.3 years and the follow-up duration was 4 +/- 3 years (range 6 months-20 years). More than two-thirds of them were treated with ACE inhibitors or angiotensin receptor blockers and 8.3 percent received the combination treatment. The DD genotype was noted in 13.3 percent of study patients, insertion/insertion in 48.3 percent and insertion/deletion genotype in 38.3 percent. Although the estimated glomerular filtration rate (eGFR) of both groups were the same during their initial presentation, the DD patients had more severe disease compared to the non-DD patients at the time of the study. Their serum creatinine and eGFR was 178 (IQR 31.3) micromol/L and 42.1 +/- 31.1 ml/min/1.73 square metres, whereas the non-DD patients had serum creatinine and eGFR of 79 (IQR: 88.3) micromol/L and 76.6 +/- 42.1 ml/min/1.73 square metres, respectively (p-value is less than 0.01). The DD patients were also found to have more severe vascular damage in their renal biopsies compared to the non-DD patients. The annual rate of decline in eGFR was not significantly different between the two groups. It was -5.7 +/- 2.2 ml/min/1.73 square metres/year for the DD group and -4.8 +/- 2.0 ml/min/1.73 square metres/year for the non-DD group (p-value is equal to 0.5). They also had severe proteinuria with UPCI of 0.09 (IQR 0.2) g/mmol creatinine vs. 0.04 (IQR 0.10) g/mmol creatinine (p-value is less than 0.01). The study also confirmed that patients who had higher systolic blood pressure, greater proteinuria and longer follow-up duration had significant renal function deterioration compared to those who did not. CONCLUSION: The DD genotype, although found in a minority of the patients, might have adversely affected the disease progression of our IgA nephropathy patients. Higher systolic blood pressure, greater proteinuria and longer follow-up duration were the other prognostic factors in IgA nephropathy patients. However, appropriate treatment, especially prompt use of renin-angiotensin-aldosterone system blockade, should stabilise the disease regardless of their genotype.

Disease Expression and HLA Types in Early and Late Onset Disease of Malaysian Patients with Systemic Lupus Erythematosus.

Age has been suggested to modify systemic lupus erythematosus expression. In this study we have attempted to study 13 patients with late onset (40 years and above) and 90 with early onset disease (below 40 years) to determine whether age-related differences in disease expression exist and whether the genetic make-up influences the age of disease onset. We found that patients with late onset disease initially presented with pericarditis (31% vs 3%, P<0.005) and a lower incidence of malar rash (31% vs 57%, p<0.05). During the disease course, there was a lower incidence of mucocutaneous symptoms especially malar rash (p<0.005) and psychosis (p<0.05) in the late onset group. Serological parameters were similar in both groups. There was a prevalence of HLA-DQA1*0103 in Chinese patients with late onset disease (pcorr=0.004). These findings suggest that a subgroup of late onset patients may experience milder disease and that the risk conferred by the HLA-DQA1*0103 may be significant among these patients.