Pressure and current balance conditions during electron beam injections from spacecraft

Electrostatic charging level of a conducting surface in response to injections of electron beams into space plasma is investigated by means of one-dimensional Vlasov code. Injections of Maxwellian beams into a vacuum shows that the surface can charge up to an electric potential phi sub s greater than W sub b, where W sub b is the average electron beam energy. Since Maxwellian beams have extended trails with electrons having energies greater than W sub b, it is difficult to quantify the charging level in terms of the energies of the injected electrons. In order to quantitatively understand the charging in excess of W sub b, simulations were carried out for water-bag types of beam with velocity distribution functions described by f(V) = A for V sub min approx. less than V approx. less than V sub max and f(V) = O otherwise, where A is a constant making the normalized beam density unity. It is found that V sub max does not directly determine the charging level. The pressure distribution in the electron sheath determines the electric field distribution near the surface. The electric field in turn determines the electrostatic potential of the vehicle. The pressure distribution is determined by the beam parameters such as the average beam velocity and the velocity spread of the beam

Thermo-acoustics and its detection in a premixed flame

A new optical technique based on light-matter interaction is devised in-house to detect thermo-acoustic disturbances generated after ignition and during propagation of a premixed flame front in a half open channel. The technique involves passing a polarized laser light through a medium whose density or refractive index varies due to the passage of acoustic waves and/or flame front and then capturing the leaked depolarised light through an analyser by a photo-detector. The technique is applied to combustor involving premixed flame propagation and tulip inversion. The thermo-acoustic signals and the flame front are distinguished by comparing the oscilloscope signal with high speed photography of the flow-field. Acoustic waves are found to intercept the flame propagation at various axial locations and time instants

Particle Access and Charging Environments in the Lunar Wake

A plasma wake a region of low density, high temperature plasma forms on the far side of the Moon when solar wind, magnetosheath, and magnetotail plasma flows past the Moon [Manka, 1973; Ogilvie et al., 1996; Farrell et al., 1998; Halekas et al., 2005]. Ion populations in these flows typically have much smaller thermal velocity than bulk speed and are therefore excluded from the plasma wake while the large thermal electron velocity allows the lighter negatively charged particles to stream ahead of the ions into the wake. Charge separation due to electrons streaming ahead of the ions into the wake from the wake boundary establishes an ambipolar electric field which impedes the motion of electron flow and accelerates ions into the wake [Ogilvie et al., 1996; Farrell et al., 1997]. We have conducted a theoretical study of acceleration (and deceleration) of charged particles in lunar plasma environments, which investigated the mechanisms responsible for allowing solar wind entry into the lunar wake, and for producing energetic particle distributions observed within the lunar wake. To this end, the investigation utilized a macroscale 3D hybrid particle-in-cell numerical model of the interaction of the Moon with external plasma environments to compute electric fields in the lunar environment for a variety of external plasma conditions and interplanetary magnetic field orientations. Ion dynamics were attained from the hybrid code while electron dynamics were determined by considering electron test particle trajectories through the fields established in the hybrid code. Results from the code will be presented to evaluate charging environments within the lunar wake

Development of bioconjugated nano-molecules against targeted microbial pathogens for enhanced bactericidal activity

The study reports development of bio-conjugated nano-molecules (BCM's) for enhanced antibacterial activity against targeted pathogens of global concern. The conjugation was achieved with biomolecular interaction of silver clusters with 3-Dichloro-5, 6-dicyano-1, 4-benzoquinone (DDQ) which was purified and characterized with TLC which displayed prominent band at R-f 0.5 and HPLC analysis displayed chromatographic peak eluting at (t(R)) 6-8 min. The LC-MS analysis displayed single major peak at t(R) = 4.610 corresponding to molecular ion peak at m/z = 227.19. The developed BCM molecule was determined with UV-Visible spectroscopy which displayed the absorbance peaks of conjugated molecules with shoulder peak observed and morphological characteristics were well defined with TEM analysis which showed cluster formation. The size ranged from 20 to 80 nm in size with majority of the BCM displaying spherical in size. The process of bio-conjugation was further studied with FTIR analysis which corresponded with different vibrational stretches owing to the presence of amide, carbonyl alkynes, nitriles and carboxylic acid groups. The presence of functional moieties was also studied using H-1 and C-13 NMR spectra. The crystalline characteristics was confirmed with XRD analysis which displayed Bragg's intensities along with additional peaks occurring at 2 theta angle corresponds to (111), (200), (220), (311) face centric cube of silver planes. The antibacterial activity of BCM's was profound against all the test pathogen which was validated and compared with standard antibiotics. Among the test pathogens, highest activity was conferred against Staphylococcus epidermidis (MTCC 435) with 29 mm. The minimal inhibition concentration of BCM's was in the range of 0.97-3.12 mu g/ml. The results of MIC were in accordance with well diffusion assay indicating the Gram + ve test pathogen Staphylococcus epidermidis to be the most sensitive. In addition, the broth dilution assay resulted in decrease in the optical density measured at 600 nm against the increase in the concentration of BCM's. The outcome of the present investigation revealed the role of bio-conjugation chemistry to increase fold activity against pathogens which can act as alternative tool to combat drug resistant menace across the globe

Modulation of inhibitory activity of xylanase - α-amylase inhibitor protein (XAIP): binding studies and crystal structure determination of XAIP- II from Scadoxus multiflorus at 1.2 Å resolution

Background: Plants produce a wide range of proteinaceous inhibitors to protect themselves against hydrolytic enzymes. Recently a novel protein XAIP belonging to a new sub-family (GH18C) was reported to inhibit two structurally unrelated enzymes xylanase GH11 and α -amylase GH13. It was shown to inhibit xylanase GH11 with greater potency than that of α-amylase GH13. A new form of XAIP (XAIP-II) that inhibits α-amylase GH13 with a greater potency than that of XAIP and xylanase GH11 with a lower potency than that of XAIP, has been identified in the extracts of underground bulbs of Scadoxus multiflorus. This kind of occurrence of isoforms of inhibitor proteins is a rare observation and offers new opportunities for understanding the principles of protein engineering by nature. Results: In order to determine the structural basis of the enhanced potency of XAIP-II against α-amylase GH13 and its reduced potency against xylanase GH11 as compared to that of XAIP, we have purified XAIP-II to homogeneity and obtained its complete amino acid sequence using cloning procedure. It has been crystallized with 0.1 M ammonium sulphate as the precipitating agent and the three-dimensional structure has been determined at 1.2 Å resolution. The binding studies of XAIP-II with xylanase GH11 and α-amylase GH13 have been carried out with surface plasmon resonance (SPR). Conclusion: The structure determination revealed that XAIP-II adopts the well known TIM barrel fold. The xylanase GH11 binding site in XAIP-II is formed mainly with loop α3-β3 (residues, 102 - 118) which has acquired a stereochemically less favorable conformation for binding to xylanase GH11 because of the addition of an extra residue, Ala105 and due to replacements of two important residues, His106 and Asn109 by Thr107 and Ser110. On the other hand, the α-amylase binding site, which consists of α-helices α6 (residues, 193 - 206), α7 (residues, 230 - 243) and loop β6-α6 (residues, 180 - 192) adopts a stereochemically more favorable conformation due to replacements of residues, Ser190, Gly191 and Glu194 by Ala191, Ser192 and Ser195 respectively in α-helix α6, Glu231 and His236 by Thr232 and Ser237 respectively in α-helix α7. As a result, XAIP-II binds to xylanase GH11 less favorably while it interacts more strongly with α-amylase GH13 as compared to XAIP. These observations correlate well with the values of 4.2 × 10-6 M and 3.4 × 10-8 M for the dissociation constants of XAIP-II with xylanase GH11 and α-amylase GH13 respectively and those of 4.5 × 10-7 M and 3.6 × 10-6 M of XAIP with xylanase GH11 and α-amylase GH13 respectively

Polysaccharide binding sites in hyaluronate lyase-crystal structures of native phage-encoded hyaluronate lyase and its complexes with ascorbic acid and lactose

Hyaluronate lyases are a class of endoglycosaminidase enzymes with a high level of complexity and heterogeneity. The main function of the Streptococcus pyogenes bacteriophage protein hyaluronate lyase, HylP2, is to degrade hyaluronan into unsaturated disaccharide units. HylP2 was cloned, over-expressed and purified to homogeneity. The recombinant HylP2 exists as a homotrimer with a molecular mass of approximately 110 kDa under physiological conditions. The HylP2 was crystallized and the crystals were soaked in two separate reservoir solutions containing ascorbic acid and lactose, respectively. The crystal structures of native HylP2 and its two complexes with ascorbic acid and lactose have been determined. HylP2 folds into four distinct domains with a central core consisting of 16 antiparallel β-strands forming an irregular triangular tube designated as triple-stranded β-helix. The structures of complexes show that three molecules each of ascorbic acid and lactose bind to protein at the sugar binding groove in the triple-stranded β-helix domain. Both ascorbic acid and lactose molecules occupy almost identical subsites in the long saccharide binding groove. Both ligands are involved in several hydrogen bonded interactions at each subsite. The binding characteristics and stereochemical properties indicate that Tyr264 may be involved in the catalytic activity of HylP2. The mutation of Tyr264 to Phe264 supports this observation

Are web corpora inferior? The Case of Czech and Slovak

Our paper describes an experiment aimed to assessment of lexical coverage in web corpora in comparison with the traditional ones for two closely related Slavic languages from the lexicographers’ perspective. The preliminary results show that web corpora should not be considered ― inferior, but rather ― different

Development of genic-SSR markers by deep transcriptome sequencing in pigeonpea [Cajanus cajan (L.) Millspaugh]

<p>Abstract</p> <p>Background</p> <p>Pigeonpea [<it>Cajanus cajan </it>(L.) Millspaugh], one of the most important food legumes of semi-arid tropical and subtropical regions, has limited genomic resources, particularly expressed sequence based (genic) markers. We report a comprehensive set of validated genic simple sequence repeat (SSR) markers using deep transcriptome sequencing, and its application in genetic diversity analysis and mapping.</p> <p>Results</p> <p>In this study, 43,324 transcriptome shotgun assembly unigene contigs were assembled from 1.696 million 454 GS-FLX sequence reads of separate pooled cDNA libraries prepared from leaf, root, stem and immature seed of two pigeonpea varieties, Asha and UPAS 120. A total of 3,771 genic-SSR loci, excluding homopolymeric and compound repeats, were identified; of which 2,877 PCR primer pairs were designed for marker development. Dinucleotide was the most common repeat motif with a frequency of 60.41%, followed by tri- (34.52%), hexa- (2.62%), tetra- (1.67%) and pentanucleotide (0.76%) repeat motifs. Primers were synthesized and tested for 772 of these loci with repeat lengths of ≥18 bp. Of these, 550 markers were validated for consistent amplification in eight diverse pigeonpea varieties; 71 were found to be polymorphic on agarose gel electrophoresis. Genetic diversity analysis was done on 22 pigeonpea varieties and eight wild species using 20 highly polymorphic genic-SSR markers. The number of alleles at these loci ranged from 4-10 and the polymorphism information content values ranged from 0.46 to 0.72. Neighbor-joining dendrogram showed distinct separation of the different groups of pigeonpea cultivars and wild species. Deep transcriptome sequencing of the two parental lines helped <it>in silico </it>identification of polymorphic genic-SSR loci to facilitate the rapid development of an intra-species reference genetic map, a subset of which was validated for expected allelic segregation in the reference mapping population.</p> <p>Conclusion</p> <p>We developed 550 validated genic-SSR markers in pigeonpea using deep transcriptome sequencing. From these, 20 highly polymorphic markers were used to evaluate the genetic relationship among species of the genus <it>Cajanus</it>. A comprehensive set of genic-SSR markers was developed as an important genomic resource for diversity analysis and genetic mapping in pigeonpea.</p

Metabolomics-Driven Mining of Metabolite Resources:Applications and Prospects for Improving Vegetable Crops

Vegetable crops possess a prominent nutri-metabolite pool that not only contributes to the crop performance in the fields, but also offers nutritional security for humans. In the pursuit of identifying, quantifying and functionally characterizing the cellular metabolome pool, biomolecule separation technologies, data acquisition platforms, chemical libraries, bioinformatics tools, databases and visualization techniques have come to play significant role. High-throughput metabolomics unravels structurally diverse nutrition-rich metabolites and their entangled interactions in vegetable plants. It has helped to link identified phytometabolites with unique phenotypic traits, nutri-functional characters, defense mechanisms and crop productivity. In this study, we explore mining diverse metabolites, localizing cellular metabolic pathways, classifying functional biomolecules and establishing linkages between metabolic fluxes and genomic regulations, using comprehensive metabolomics deciphers of the plant’s performance in the environment. We discuss exemplary reports covering the implications of metabolomics, addressing metabolic changes in vegetable plants during crop domestication, stage-dependent growth, fruit development, nutri-metabolic capabilities, climatic impacts, plant-microbe-pest interactions and anthropogenic activities. Efforts leading to identify biomarker metabolites, candidate proteins and the genes responsible for plant health, defense mechanisms and nutri-rich crop produce are documented. With the insights on metabolite-QTL (mQTL) driven genetic architecture, molecular breeding in vegetable crops can be revolutionized for developing better nutritional capabilities, improved tolerance against diseases/pests and enhanced climate resilience in plants

Monkeypox Viruses: Resurgence of Global Threat to Mankind

The unprecedented outbreaks of monkeypox viruses in non-endemic regions have created grave concern for global health. The World Health Organization has declared a public health emergency of international concern and stated the seriousness of monkeypox viruses. The gravity of this zoonotic disease cannot be underestimated, owing to the fact that this viral infection can cause pathetic situations if ignored. Keeping these lacunas, the scientific communities have expressed their interest towards the study of monkeypox viruses. Hence the present review discusses the etiological features, historical events, and vaccination along with management strategies to combat and counter the sudden outbreak. The review also highlights the current Indian scenario of the monkeypox virus; with scanty reports available, the present contributes towards the growing scientific knowledge to prevent a future threats to mankind