This paper describes a novel technique to produce cellulose microfibrils through mechanical methods. The technique involved a combination of severe shearing in a refiner, followed by high-impact crushing under liquid nitrogen. Fibers treated in this way were subsequently either freeze-dried or suspended in water. The fibers were characterized using SEM, TEM, AFM, and high-resolution optical microscopy. In the freeze-dried batch, 75% of the fibrils had diameters of 1 μm and below, whereas in the water dispersed batch, 89% of the fibrils had diameters in this range. The aspect ratio of the microfibrils ranged between 15 and 55 for the freeze-dried fibrils, and from 20 to 85 for the fibrils dispersed in water. These measurements suggest that the microfibrils have the potential to produce composites with high strength and stiffness for high-performance applications. The microfibrils in water were compounded with polylactic acid polymer to form a biocomposite. Laser confocal microscopy showed that the microfibrils were well dispersed in the polymer matrix.

In this study, the reinforcing potential of cellulose “microfibres” obtained from bleached softwood kraft pulp was demonstrated in a matrix of polyvinyl alcohol (PVA). Microfibres are defined as fibres of cellulose of 0.1–1 μm in diameter, with a corresponding minimum length of 5–50 μm. Films cast with these microfibres in PVA showed a doubling of tensile strength and a 2.5-fold increase in stiffness with 5% microfibre loading. The theoretical stiffness of a microfibre was calculated as 69 GPa. The study also demonstrated that the strength of the composite was greater at 5% microfibre loading compared to 10% loading. Comparative studies with microcrystalline cellulose showed that the minimum aspect ratio of the reinforcing agent is more criticalthan its crystallinity in providing reinforcement in the composite.

IntroductionIn high-income countries, the self-rated health (SRH) item is used in health surveys to capture the population’s general health because of its simplicity and satisfactory validity and reliability. Despite scepticism about its use in low-income and middle-income countries, India implemented the SRH item in many of its demographic and population health surveys, but evidence of its validity is lacking. The objective was to assess the construct validity of the SRH item in India.MethodsData for 4492 men and 4736 women from the Indian sample of the World Health Survey (2003) were used. Overall, 43 health status indicators were grouped into health dimensions (physical, mental and functional health, chronic diseases, health behaviours) and the SRH item was regressed on these indicators by using sex-stratified multivariable linear regressions, adjusted with demographic and socioeconomic variables.ResultsRespondents (participation rate 95.6%; mean age 38.9 years) rated their health as very good (21.8%), good (36.4%), moderate (26.6%), bad (13.2%) or very bad (2.0%). Among men, the adjusted explained SRH variance by health dimensions ranged between 18% and 41% (physical 33%, mental 32%, functional health 41%, chronic diseases 23%, health behaviours 18%). In multivariable models, the overall explained variance increased to 45%. The 43 health status indicators were associated with SRH and their effect sizes were in the expected direction. Among women, results were similar (overall explained variance 48%).ConclusionThe SRH item has satisfactory construct validity and may be used to monitor health status in demographic and population health surveys of India.

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Therefore, intracellular iron overload caused DNA fragmentation, which may ultimately hamper lymphocyte function, and this may contribute to immune dysfunction and increased susceptibility to infections in thalassemia patients as indicated by the good correlation (R = 0.91) between lymphocyte DNA damage and rate of infection found in this study.