A structural analysis of M protein in coronavirus assembly and morphology

The M protein of coronavirus plays a central role in virus assembly, turning cellular membranes into workshops where virus and host factors come together to make new virus particles. We investigated how M structure and organization is related to virus shape and size using cryo-electron microscopy, tomography and statistical analysis. We present evidence that suggests M can adopt two conformations and that membrane curvature is regulated by one M conformer. Elongated M protein is associated with rigidity, clusters of spikes and a relatively narrow range of membrane curvature. In contrast, compact M protein is associated with flexibility and low spike density. Analysis of several types of virus-like particles and virions revealed that S protein, N protein and genomic RNA each help to regulate virion size and variation, presumably through interactions with M. These findings provide insight into how M protein functions to promote virus assembly.

Analysis of expression of flagella by Salmonella enterica serotype Typhimurium by monoclonal antibodies recognising both phase specific and common epitopes

Monoclonal antibodies specific for phase 1 ("i" antigen), phase 2 ("1,2" antigen) and common epitopes of the flagellins of Salmonella enterica serotype Typhimurium were raised. Having confirmed their specificity, the monoclonal antibodies were used to develop semi-quantitative ELISAs in order to assess the relative expression of the two phases by strains of Typhimurium. The majority of Typhimurium strains representative of a wide cross-section of definitive types from animal and environmental sources preferentially expressed phase 1 antigen in vitro. DT40 strains were unique in expressing phase 2 preferentially. The ratio of phase 1 to phase 2 expressed by strains tended to be constant for any one strain when strains were grown on a number of conventional laboratory media. However, the ratio of phases was shown to be modulated by incubation at 42 degreesC and buffering media at pH values, notably 4.5, other than neutral. Selenite broth and Rambach media repressed flagellation. Crown Copyright (C) 2001 Published by Elsevier Science B.V. All rights reserved.

Control and analysis of oriented thin films of lipid inverse bicontinuous cubic phases using grazing incidence small-angle X‑ray scattering

Lipid cubic phases are complex nanostructures that form naturally in a variety of biological systems, with applications including drug delivery and nanotemplating. Most X-ray scattering studies on lipid cubic phases have used unoriented polydomain samples as either bulk gels or suspensions of micrometer-sized cubosomes. We present a method of investigating cubic phases in a new form, as supported thin films that can be analyzed using grazing incidence small-angle X-ray scattering (GISAXS). We present GISAXS data on three lipid systems: phytantriol and two grades of monoolein (research and industrial). The use of thin films brings a number of advantages. First, the samples exhibit a high degree of uniaxial orientation about the substrate normal. Second, the new morphology allows precise control of the substrate mesophase geometry and lattice parameter using a controlled temperature and humidity environment, and we demonstrate the controllable formation of oriented diamond and gyroid inverse bicontinuous cubic along with lamellar phases. Finally, the thin film morphology allows the induction of reversible phase transitions between these mesophase structures by changes in humidity on subminute time scales, and we present timeresolved GISAXS data monitoring these transformations.

An enhanced model for small-signal analysis of the phase-shifted full-bridge converter

This paper presents an in-depth critical discussion and derivation of a detailed small-signal analysis of the Phase-Shifted Full-Bridge (PSFB) converter. Circuit parasitics, resonant inductance and transformer turns ratio have all been taken into account in the evaluation of this topology’s open-loop control-to-output, line-to-output and load-to-output transfer functions. Accordingly, the significant impact of losses and resonant inductance on the converter’s transfer functions is highlighted. The enhanced dynamic model proposed in this paper enables the correct design of the converter compensator, including the effect of parasitics on the dynamic behavior of the PSFB converter. Detailed experimental results for a real-life 36V-to-14V/10A PSFB industrial application show excellent agreement with the predictions from the model proposed herein.1

Getting the measure of derivational morphology in adult speech a corpus analysis using MorphoQuantics

This paper describes the methodology used to compile a corpus called MorphoQuantics that contains a comprehensive set of 17,943 complex word types extracted from the spoken component of the British National Corpus (BNC). The categorisation of these complex words was derived primarily from the classification of Prefixes, Suffixes and Combining Forms proposed by Stein (2007). The MorphoQuantics corpus has been made available on a website of the same name; it lists 554 word-initial and 281 word-final morphemes in English, their etymology and meaning, and records the type and token frequencies of all the associated complex words containing these morphemes from the spoken element of the BNC, together with their Part of Speech. The results show that, although the number of word-initial affixes is nearly double that of word-final affixes, the relative number of each observed in the BNC is very similar; however, word-final affixes are more productive in that, on average, the frequency with which they attach to different bases is three times that of word-initial affixes. Finally, this paper considers how linguists, psycholinguists and psychologists may use MorphoQuantics to support their empirical work in first and second language acquisition, and clinical and educational research.

Phylogenetic analysis of the Brazilian microendemic Paepalanthus subgenus Xeractis (Eriocaulaceae) inferred from morphology

Paepalanthus subgenus Xeractis (Eriocaulaceae) comprises 28 recognized species endemic to the Espinhaco Range, in Minas Gerais state, Brazil. Most species of the subgenus are restricted to small localities and critically endangered, but still in need of systematic study. The monophyly of the subgenus has already been tested, but only with a few species. Our study presents the first phylogenetic hypothesis within the group, based on morphology. A maximum parsimony analysis was conducted on a matrix of 30 characters for 30 terminal taxa, including all species of the subgenus and two outgroups. The biogeographical hypotheses for the subgenus were inferred based on dispersal-vicariance analysis (DIVA). The analysis provided one most-parsimonious hypothesis that supports most of the latest published subdivisions (sections and series). However, some conflicts remain concerning the position of a few species and the relationships between sections. The distribution and origin(s) of microendemism are also discussed, providing the ground for conservation strategies to be developed in the region. (C) 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 167, 137-152.

Wave optics analysis by phase-shifting real-time holographic interferometry

The purpose of this work is to study the potentialities in the phase-shifting real-time holographic interferometry using photorefractive crystals as the recording medium for wave-optics analysis in optical elements and non-linear optical materials. This technique was used for obtaining quantitative measurements from the phase distributions of the wave front of lens and lens systems along the propagation direction with in situ visualization, monitoring and analysis in real time. (C) 2008 Elsevier GmbH. All rights reserved.

Light-induced lens analysis in photorefractive crystals employing phase-shifting real-time holographic interferometry

The purpose of this work is to study the potentialities of phase-shifting real-time holographic interferometry for the analysis of light-induced lens in photoreffactive and nonlinear optical materials. We show that this technique can be used for quantitative evaluation of the phase distribution of a wavefront changed by a light-induced lens and, consequently, the refractive index changes in these materials. The basic principle of this technique combines real-time holographic interferometry with phase-shifting technique for interferogram analysis. This method is demonstrated with in situ visualization, monitoring and analysis in real-time and uses a Bi(12)SiO(20) crystal as the holographic medium and a Bi(12)TiO(20) as the test sample. (C) 2008 Elsevier B.V. All rights reserved.

Vanadium Pentoxide Nanostructures: An Effective Control of Morphology and Crystal Structure in Hydrothermal Conditions

A systematic study was made of the synthesis of V(2)O(5)center dot nH(2)O nanostructures, whose morphologies, crystal structure, and amount of water molecules between the layered structures were regulated by strictly controlling the hydrothermal treatment variables. The synthesis involved a direct hydrothermal reaction between V(2)O(5) and H(2)O(2), without the addition of organic surfactant or inorganic ions. The experimental results indicate that high purity nanostructures can be obtained using this simple and clean synthetic route. Oil the basis of a study of hydrothermal treatment variables such as reaction temperature and time, X-ray diffraction (XRD) and scanning transmission electron microscopy (STEM) revealed that it was possible to obtain nanoribbons of the V(2)O(5)center dot nH(2)O monoclinic phase and nanowires or nanorods of the V(2)O(5)center dot nH(2)O orthorhombic phase. Thermal gravimetric analysis (TGA) shows also that the water content in the Structure call be controlled at appropriate hydrothermal conditions. Concerning the oxidation state of the vanadium atoms of as-obtained samples, a mixed-valence state composed of V(4+) and V(5+) was observed ill the V(2)O(5)center dot nH(2)O monoclinic phase, while the valence of the vanadium atoms was preferentially 5+ in the V(2)O(5)center dot nH(2)O orthorhombic phase. The X-ray absorption near-edge structure (XANES) results also indicated that the local structure of vanadium possessed a higher degree of symmetry in the V(2)O(5)center dot nH(2)O monoclinic phase.

Thermal analysis and structural investigation of different dental composite resins

The structural and thermal properties of three different dental composite resins, Filtek (TM) Supreme XT, Filtek (TM) Z-250 and TPHA (R)(3) were investigated in this study. The internal structures of uncured and cured resins with blue light-emitting diodes (LEDs) were examined by Micro-Raman spectroscopy. Thermal analysis techniques as DSC, TG and DTG methods were used to investigate the temperature characteristics, as glass transition (T (g) ), degradation, and the thermal stability of the resins. The results showed that the TPHA (R)(3) and Filtek (TM) Supreme XT presented very similar T (g) values, 48 and 50A degrees C, respectively, while the Filtek (TM) Z-250 composite resin presented a higher one, 58A degrees C. AFM microscope was utilized in order to analyze the sample morphologies, which possess different fillers. The composed resin Filtek (TM) Z-250 has a well interconnected more homogeneous morphology, suggesting a better degree of conversion correlated to the glass phase transition temperature. The modes of vibration of interest in the resin were investigated using Raman spectroscopy. It was possible to observe the bands representative for the C=C (1630 cm(-1)) and C=O(1700 cm(-1)) vibrations were studied with respect to their compositions and polymerization. It was observed that the Filtek (TM) Z -250 resin presents the best result related to the thermal properties and polymerization after light curing among the other resins.

Comparative analysis of the volatile fraction from Annona cherimola Mill. cultivars by solid-phase microextraction and gas chromatography–quadrupole mass spectrometry detection

The analysis of volatile compounds in Funchal, Madeira, Mateus and Perry Vidal cultivars of Annona cherimola Mill. (cherimoya) was carried out by headspace solid-phase microextraction (HS-SPME) combined with gas chromatography–quadrupole mass spectrometry detection (GC–qMSD). HS-SPME technique was optimized in terms of fibre selection, extraction time, extraction temperature and sample amount to reach the best extraction efficiency. The best result was obtained with 2 g of sample, using a divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fibre for 30 min at 30 °C under constant magnetic stirring (800 rpm). After optimization of the extraction methodology, all the cherimoya samples were analysed with the best conditions that allowed to identify about 60 volatile compounds. The major compounds identified in the four cherimoya cultivars were methyl butanoate, butyl butanoate, 3-methylbutyl butanoate, 3-methylbutyl 3-methylbutanoate and 5-hydroxymethyl-2-furfural. These compounds represent 69.08 ± 5.22%, 56.56 ± 15.36%, 56.69 ± 9.28% and 71.82 ± 1.29% of the total volatiles for Funchal, Madeira, Mateus and Perry Vidal cultivars, respectively. This study showed that each cherimoya cultivars have 40 common compounds, corresponding to different chemical families, namely terpenes, esters, alcohols, fatty acids and carbonyl compounds and using PCA, the volatile composition in terms of average peak areas, provided a suitable tool to differentiate among the cherimoya cultivars.

A new and improved strategy combining a dispersive-solid phase extraction-based multiclass method with ultra high pressure liquid chromatography for analysis of low molecular weight polyphenols in vegetables

This paper reports on the development and optimization of a modified Quick, Easy, Cheap Effective, Rugged and Safe (QuEChERS) based extraction technique coupled with a clean-up dispersive-solid phase extraction (dSPE) as a new, reliable and powerful strategy to enhance the extraction efficiency of free low molecular-weight polyphenols in selected species of dietary vegetables. The process involves two simple steps. First, the homogenized samples are extracted and partitioned using an organic solvent and salt solution. Then, the supernatant is further extracted and cleaned using a dSPE technique. Final clear extracts of vegetables were concentrated under vacuum to near dryness and taken up into initial mobile phase (0.1% formic acid and 20% methanol). The separation and quantification of free low molecular weight polyphenols from the vegetable extracts was achieved by ultrahigh pressure liquid chromatography (UHPLC) equipped with a phodiode array (PDA) detection system and a Trifunctional High Strength Silica capillary analytical column (HSS T3), specially designed for polar compounds. The performance of the method was assessed by studying the selectivity, linear dynamic range, the limit of detection (LOD) and limit of quantification (LOQ), precision, trueness, and matrix effects. The validation parameters of the method showed satisfactory figures of merit. Good linearity (View the MathML sourceRvalues2>0.954; (+)-catechin in carrot samples) was achieved at the studied concentration range. Reproducibility was better than 3%. Consistent recoveries of polyphenols ranging from 78.4 to 99.9% were observed when all target vegetable samples were spiked at two concentration levels, with relative standard deviations (RSDs, n = 5) lower than 2.9%. The LODs and the LOQs ranged from 0.005 μg mL−1 (trans-resveratrol, carrot) to 0.62 μg mL−1 (syringic acid, garlic) and from 0.016 μg mL−1 (trans-resveratrol, carrot) to 0.87 μg mL−1 ((+)-catechin, carrot) depending on the compound. The method was applied for studying the occurrence of free low molecular weight polyphenols in eight selected dietary vegetables (broccoli, tomato, carrot, garlic, onion, red pepper, green pepper and beetroot), providing a valuable and promising tool for food quality evaluation.