Previous work has shown that the formation of a network structure of nanoparticles within a polymer matrix can significantly reduce nanocomposite flammability and that viscoelastic properties could ...be utilized to predict their flammability reduction. The present work extends this type of investigation to the study of clay and carbon nanotube nanocomposites. In particular, we study PS/clay, PS/MWNT, PMMA/clay, and PMMA/SWNT nanocomposites. At a clay level of about 10% by mass, the network structure is formed for the PS and the PMMA clay nanocomposites; it requires a level of about 0.5% with the SWNT and 2% with the MWNT. These samples showed significantly reduced mass loss rates of PS and PMMA. However, the solid residues collected from radiative gasification tests of PS/clay and PMMA/clay showed many small cracks, despite the network formation within the initial sample. This is in contrast to the smooth, continuous residues (no cracks or openings) for PS/MWNT and PMMA/SWNT nanocomposites. The cracks in the clay samples are probably formed due to weaker network at elevated temperatures due to weaker bridging interaction between clay platelets as compared to stronger network resulting from dense entanglement and bridging of carbon nanotubes.
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Date fruit is a good source of bioactive compounds and natural sugar. It has the potential to be utilized as a substitute for added sugar. Although several forms of dates-such as fresh dates, date ...paste, and date syrup-are available in the market and used for different applications, free-flow date powder would be highly beneficial in improving shelf-life, ease of handling, and blendability with various foods prepared domestically and in industry. The objective of this study was to produce date powder in a pilot-scale spray dryer and determine its physicochemical qualities. Date powder was produced at eight processing conditions (2 carrier agents (maltodextrin (MD) and gum arabic (GA) × 2 inlet air temperature (150°C and 170°C) × 2 feedstock flow rates (25 ml/min and 40 ml/min)). To the carrier agent was added at 0.4 kg per 1.0 kg of date fruits (dry weight basis), and the feedstock to the spray dryer was prepared at 20% concentration. Date powder was obtained in all eight treatments. Color (L*a*b* values), moisture content, bulk density, wettability, solubility index, hygroscopicity, microstructure analysis (using scanning electron microscope (SEM)), and total phenolic compounds were determined for the spray-dried date powder. The physicochemical characteristics of date powder varied significantly with respect to the processing conditions. Although physical properties of date powder were significantly affected by the carrier agent, there was no difference in total phenolic compounds between date powders produced with MD and GA. An SEM study revealed that date powder produced with MD had smooth, regular-shaped spherical particles but with severe agglomeration. Date powder with GA had relatively smaller particles of irregular sphere with dented surfaces.
Detection algorithms in a nonhomogeneous clutter environment have to contend with the problem of excessive false alarm rates when the clutter is not sufficiently suppressed. Prior to signal ...detection, adaptive receivers must either "null" or "whiten" the clutter. The former approach requires estimates of the basis vectors of the clutter subspace while the latter requires estimates of the covariance matrix of the clutter. It may be preferable to null the clutter when the dimensionality of the clutter subspace (M) is small in comparison to the length of the data vector coherently processed (N) and also when the signal to be detected is not substantially within the clutter-plus-noise subspace. Depending on the scenario, radar clutter data may have a variety of effects such as clutter discretes, data dropouts due to terrain masking that cause shadowing, multipath effects, and non-Gaussian amplitude statistics. We consider a statistical model which can account for some of these effects and apply the model to design an algorithm to obtain a maximum likelihood estimate (MLE) of the orthonormal basis vectors of the clutter-plus-noise subspace. We show that the problem can be reformulated to develop a recursive approach for MLE based on the expectation-maximization (EM) algorithm. Results of the analysis show that each training vector must be scaled by a nonnegative scale factor from the interval 0,1 prior to subspace estimation. The scale factor applied to each training vector increases monotonically with the subspace clutter-plus-noise power of the vector. Conditions for the existence and uniqueness of the solution are considered. A statistical interpretation of the solution is provided along with sample simulation results.
In this study, microwave heating has been considered for in-shell egg pasteurization. In the first part, the effects of temperature (0–62
°C) and frequency (200
MHz to 10
GHz) on the dielectric ...properties of egg components were investigated. In the second part, individual egg components as well as intact in-shell eggs were brought to pasteurization temperature in a laboratory-scale microwave oven working at 2450
MHz using different (0.75, 1 and 2
W
g
−1) power densities and the heating curve was analyzed to determine heating time required for different power levels. Under the conditions studied, it was demonstrated that the albumen had higher dielectric properties and loss factors leading to its faster heating rate in a microwave environment than the yolk. This was corroborated by the microwave heating trials performed on individual components where albumen always heated up faster. Laboratory trials on microwave heating of in-shell eggs indicated that, on the contrary, the heating rates of both albumen and yolk were similar. Microwave heating appeared to have great potential for in-shell egg pasteurization. Models for calculating the
ε′ and
ε″ at a given frequency and temperature for shell egg components were also presented.
Dissociation between caloric and head impulse test results in patients with vestibular disorders has been well documented since the introduction of video head impulse testing. Prior to the ...introduction of video head impulse testing, vestibular diagnostic services relied mainly on caloric testing, and it is now known that the caloric testing shows more positive results than video head impulse testing. A dissipation model was proposed to explain this dissociation.Case reportsThis paper presents two cases in which caloric testing indicated an absent or significantly reduced response on the horizontal semicircular canal plane but video head impulse testing showed near-normal or normal vestibulo-ocular reflex gain on the same plane.
This report supports the dissipation theory and questions the functional relevance of canal paresis values calculated from caloric test results.
Removal of moisture from biological materials, popularly called drying, has numerous benefits, including ease of handling due to reduction in bulk, resulting in reduced handling costs. Moreover, ...drying prevents microbial growth and spoilage. Though different drying techniques share a common objective, conceptually they are different and require modification/adaptation based on the biomaterial that is dried. There have been significant scientific advancements in the past century in the field of drying of foods, fibers, and fuel. This article will provide an extensive review of various drying pretreatments and different hybrid drying techniques, including supercritical and fluidized bed concepts, microwave drying, superheated steam drying, and heat pump drying to meet tomorrow's food and energy needs.
Significance
Mature asexual stages of
Plasmodium falciparum
-infected erythrocytes (IEs) bind to endothelium to avoid splenic clearance. The PfEMP1 family is the major cytoadhesion ligand at the IE ...surface and is essential for parasite sequestration. In this study, we show that complement component 1s (C1s), found in serum, cleaves PfEMP1 on the IEs to prevent binding to endothelial cells. We find that the C1s cleavage sites are maintained at semiconserved arginine motifs located at interdomain regions between PfEMP1 receptor-binding domains and upstream of the transmembrane region. This suggests that parasites have taken advantage of a human serum protease, either to escape antibody recognition of sequestered parasites or to dampen sequestration and pathogenesis from uncontrolled inflammatory responses threatening host survival.
Cytoadhesion of
Plasmodium falciparum
-infected erythrocytes (IEs) to the endothelial lining of blood vessels protects parasites from splenic destruction, but also leads to detrimental inflammation and vessel occlusion. Surface display of the
P. falciparum
erythrocyte membrane protein 1 (PfEMP1) adhesion ligands exposes them to host antibodies and serum proteins. PfEMP1 are important targets of acquired immunity to malaria, and through evolution, the protein family has expanded and diversified to bind a select set of host receptors through antigenically diversified receptor-binding domains. Here, we show that complement component 1s (C1s) in serum cleaves PfEMP1 at semiconserved arginine motifs located at interdomain regions between the receptor-binding domains, rendering the IE incapable of binding the two main PfEMP1 receptors, CD36 and endothelial protein C receptor (EPCR). Bioinformatic analyses of PfEMP1 protein sequences from 15
P. falciparum
genomes found the C1s motif was present in most PfEMP1 variants. Prediction of C1s cleavage and loss of binding to endothelial receptors was further corroborated by testing of several different parasite lines. These observations suggest that the parasites have maintained susceptibility for cleavage by the serine protease, C1s, and provides evidence for a complex relationship between the complement system and the
P. falciparum
cytoadhesion virulence determinant.
Porous volumetric capture elements in microfluidic sensors are advantageous compared to planar capture surfaces due to higher reaction site density and decreased diffusion lengths that can reduce ...detection limits and total assay time. However a mismatch in refractive indices between the capture matrix and fluid within the porous interstices results in scattering of incident, reflected, or emitted light, significantly reducing the signal for optical detection. Here we demonstrate that perfusion of an index-matching fluid within a porous matrix minimizes scattering, thus enhancing optical signal by enabling the entire capture element volume to be probed. Signal enhancement is demonstrated for both fluorescence and absorbance detection, using porous polymer monoliths in a silica capillary and packed beds of glass beads within thermoplastic microchannels, respectively. Fluorescence signal was improved by a factor of 3.5× when measuring emission from a fluorescent compound attached directly to the polymer monolith, and up to 2.6× for a rapid 10 min direct immunoassay. When combining index matching with a silver enhancement step, a detection limit of 0.1 ng mL(-1) human IgG and a 5 log dynamic range was achieved. The demonstrated technique provides a simple method for enhancing optical sensitivity for a wide range of assays, enabling the full benefits of porous detection elements in miniaturized analytical systems to be realized.
This research evaluated the effects of microwave and high-voltage pretreatments on convective freeze drying of mushrooms (Agaricus bisporus) independently. The effect of the microwave (5 W/g for ...5 min) and high electric field (HEF; 430 kV/m for 15 min) as pretreatments on enhancement of the drying rates during subsequent drying and the value addition due to the above pretreatments on the quality of the final dehydrated products were investigated. An exponential mathematical model was developed by fitting the drying kinetics to the Page equation to predict the effects of the pretreatments on the drying kinetics of the mushrooms. The parameters considered for the evaluation of product quality project included color, texture, shrinkage properties, and rehydration ratio of the dried mushrooms. The drying rate of HEF-pretreated mushrooms was found to be unaffected overall when compared to the control and the HEF pretreatment resulted in better quality product and less overall shrinkage. Freeze drying of the pretreated mushrooms was found to result in slower drying rate but better overall quality and rehydration ratio.
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