Clinical and Laboratory Features of Human Plasmodium knowlesi Infection

Background—Plasmodium knowlesi is increasingly recognized as a cause of human malaria in Southeast Asia but there are no detailed prospective clinical studies of naturally acquired infections. Methods—In a systematic study of the presentation and course of patients with acute P. knowlesi infection, clinical and laboratory data were collected from previously untreated, nonpregnant adults admitted to the hospital with polymerase chain reaction–confirmed acute malaria at Kapit Hospital (Sarawak, Malaysia) from July 2006 through February 2008. Results—Of 152 patients recruited, 107 (70%) had P. knowlesi infection, 24 (16%) had Plasmodium falciparum infection, and 21 (14%) had Plasmodium vivax. Patients with P. knowlesi infection presented with a nonspecific febrile illness, had a baseline median parasitemia value at hospital admission of 1387 parasites/μL (interquartile range, 6–222,570 parasites/μL), and all were thrombocytopenic at hospital admission or on the following day. Most (93.5%) of the patients with P. knowlesi infection had uncomplicated malaria that responded to chloroquine and primaquine treatment. Based on World Health Organization criteria for falciparum malaria, 7 patients with P. knowlesi infection (6.5%) had severe infections at hospital admission. The most frequent complication was respiratory distress, which was present at hospital admission in 4 patients and developed after admission in an additional 3 patients. P. knowlesi parasitemia at hospital admission was an independent determinant of respiratory distress, as were serum creatinine level, serum bilirubin, and platelet count at admission (P < .002 for each). Two patients with knowlesi malaria died, representing a case fatality rate of 1.8% (95% confidence interval, 0.2%–6.6%). Conclusions—Knowlesi malaria causes a wide spectrum of disease. Most cases are uncomplicated and respond promptly to treatment, but approximately 1 in 10 patients develop potentially fatal complications

Active microrheology and simultaneous visualization of sheared phospholipid monolayers

Two-dimensional films of surface-active agents—from phospholipids and proteins to nanoparticles and colloids—stabilize fluid interfaces, which are essential to the science, technology and engineering of everyday life. The 2D nature of interfaces present unique challenges and opportunities: coupling between the 2D films and the bulk fluids complicates the measurement of surface dynamic properties, but allows the interfacial microstructure to be directly visualized during deformation. Here we present a novel technique that combines active microrheology with fluorescence microscopy to visualize fluid interfaces as they deform under applied stress, allowing structure and rheology to be correlated on the micron-scale in monolayer films. We show that even simple, single-component lipid monolayers can exhibit viscoelasticity, history dependence, a yield stress and hours-long time scales for elastic recoil and aging. Simultaneous visualization of the monolayer under stress shows that the rich dynamical response results from the cooperative dynamics and deformation of liquid-crystalline domains and their boundaries

Phase behavior of nanotube suspensions: from attraction induced percolation to liquid crystalline phases

This article presents an overview of recent studies on the behavior of carbon nanotube dispersions. The effect of attractive interactions on the percolation threshold is investigated. Contrary to this, we show that carbon nanotubes experiencing repulsive interactions exhibit a different phase behavior including liquid crystallinity

Synthesis and Properties of PVA/Carbon Nanotube Nanocomposites

This chapter is an overview of the synthesis and properties of PVA/nanotube composites. Various films and fibers have been processed from carbon nanotube and PVA dispersions. Compared to other polymers, PVA exhibits particularly strong interaction with single-walled as well as multiwalled carbon nanotubes. This leads to unique properties which are not oberved in other nanotube polymer nanocomposites. In particular, this literature review confirms that nanotubes can promote PVA crystallization in the vicinity of their interface. This yields imporvements of mechanical stress transfer. This effect can be enhanced with the surface functionalization of carbon nanotubes, in particular with hydroxyl or carboxyl groups, which display hudrogen bonds with PVA. Beyond the usual mechanical and electrical performances, this review also points out the emergence of other original properties, like the remarkable capabillity of some nanotube/PVA composites to absorb mechanical energy and shape memory phenomena that differ from traditional behaviors of other polymrers. These features are opening new investigation fields, in which several fundamental questions will have to be solved. But they also offer new opportunities for a variety of applications like smart or protective clothing, helmets, bullet proof vests, or active composites

Improved strain sensing performance of glass fiber polymer composites with embedded pre-stretched polyvinyl alcohol-carbon nanotube fibers

Polyvinyl alcohol-carbon nanotube (PVA-CNT) fibers differing on their pre-stretching condition were embedded in glass fiber reinforced plastic (GFRP) composites and used as strain sensors for damage monitoring of the composite. Strain sensing of the composite was made by the in situ measurement of the embedded fiber's electrical resistance change during the mechanical tests. Four glass fiber composite plates were manufactured; each one had embedded a different type of produced PVA-CNT fibers. The multi-functional materials were tested in monotonic tensile tests as well as in progressive damage accumulation tests. The electrical resistance readings of the PVA-CNT fibers were correlated with axial strain values, taking into account the induced damage of the composite. It has been demonstrated that increasing the fiber's pre-stretching ratio, its electrical resistance response increases due to higher degree of the CNTs alignment in the PVA matrix. Higher fiber pre-stretching degree enables the better strain monitoring of the composite due to higher measured electrical resistance change values noticed for the same applied axial strain values. To this end, it enables for the better monitoring of the progressive damage accumulation inside the composite

Thermodynamics and X-ray studies of 2-alcohol monolayers at the air water interface

PACS. 61.10.-iX-ray diffraction and scattering - 64.70.Dv Solid-liquid transitions - 68.10.CrSurface energy (surface tension, interface tension, angle of contact, etc.),

Structural and mechanical properties of single-wall carbon nanotube fibers

We report quantitative experimental study correlating the structure and mechanical properties of fibers made from single-walled carbon nanotubes SWNTs and polyvinyl alcohol PVA. A post-synthesis solvent drawing treatment is used to vary nanotube alignment, whose detailed understanding is a prerequisite for fiber development. Quantitative analysis of nanotube alignment within the fibers with different draw ratios is performed using x-ray scattering. The method is described in detail, and we also show that the improvement of nanotube alignment with draw ratio can be understood within a model of induced orientation at constant volume. Young's modulus and tensile strength increase with nanotube alignment. This is modeled using continuum mechanics in qualitative agreement with experiment, however quantitative differences show that nanotube alignment is not the only parameter controlling the fiber mechanical properties. We suggest that interaction between the SWNTs and PVA chains should also play a significant role

Kinetics of fiber solidification

Many synthetic or natural fibers are produced via the transformation of a liquid solution into a solid filament, which allows the wet processing of high molecular weight polymers, proteins, or inorganic particles. Synthetic wet-spun fibers are used in our everyday life from clothing to composite reinforcement applications. Spun fibers are also common in nature. Silk solidification results from the coagulation of protein solutions....