Brownian cluster dynamics with short range patchy interactions. Its application to polymers and step-growth polymerization

We present a novel simulation technique derived from Brownian cluster dynamics used so far to study the isotropic colloidal aggregation. It now implements the classical Kern-Frenkel potential to describe patchy interactions between particles. This technique gives access to static properties, dynamics and kinetics of the system, even far from the equilibrium. Particle thermal motions are modeled using billions of independent small random translations and rotations, constrained by the excluded volume and the connectivity. This algorithm, applied to a single polymer chain leads to correct static and dynamic properties, in the framework where hydrodynamic interactions are ignored. By varying patch angles, various chain flexibilities can be obtained. We have used this new algorithm to model step-growth polymerization under various solvent qualities. The polymerization reaction is modeled by an irreversible aggregation between patches while an isotropic finite square-well potential is superimposed to mimic the solvent quality. In bad solvent conditions, a competition between a phase separation (due to the isotropic interaction) and polymerization (due to patches) occurs. Surprisingly, an arrested network with a very peculiar structure appears. It is made of strands and nodes. Strands gather few stretched chains that dip into entangled globular nodes. These nodes act as reticulation points between the strands. The system is kinetically driven and we observe a trapped arrested structure. That demonstrates one of the strengths of this new simulation technique. It can give valuable insights about mechanisms that could be involved in the formation of stranded gels.Comment: 55 pages, 32 figure

Effect of eight weeks land and sand based plyometric training on selected physical and physiological variables

The purpose of the study was to analyze the effect of eight weeks land based and sand based plyometric training on selected physical and physiological variables among inter collegiate level sportspersons pursuing their graduation under Kuvempu University. Subjects for the study were thirty (30) intercollegiate level sportspersons pursuing their graduation in Shivamogga. Their age ranged between 20 to 25 years. Purposive random sampling was observed in order to ascertain minimum levels of fitness of the sportspersons. Fifteen students each were placed randomly into plyometric training groups namely Land (N=15) and Sand (N=15) surfaces. In order to examine the efficacy of plyometric training on different surfaces following tests were conducted on all the subjects under the study. The subjects underwent these tests twice during the course of study i.e pre-test and post-test. The variables selected for the study were speed, dynamic strength, lower body explosiveness, agility, body composition and resting heart rate. Suitable standard tests were selected for assessing attributes. Paired sample ‘t’ test was used as a statistical technique apart from descriptive statistics. Within the limitations of the present investigation it is concluded that the speed aspect of physical fitness can be significantly enhanced through sand based plyometric training as compared to land based plyometric training

De Quervain`s disease: evaluation by high resolution ultrasonography

Background: De Quervain's tenosynovitis is a stenosing tenosynovitis of the first extensor compartment of wrist and leads to wrist pain and impaired function of wrist and hand.  The aim of this study is to evaluate the role of high resolution ultrasonography in diagnosing suspected cases of de Quervain’s tenosynovitis and also to evaluate the role of high resolution ultrasonography in detecting the anatomical variants of the first extensor compartment which are predisposing conditions for de Quervain’s tenosynovitis.Methods: A prospective study of 15 consecutive cases who were referred with clinical diagnosis of de Quervain`s disease was done with ultrasonography in the department of Radio-diagnosis and findings were carefully analysed.Results: Thickened extensor retinaculum over the first extensor compartment was found in all the cases. Mean thickness of the thickened retinaculum is 1.65 mm. In 60% of cases multiple slips of APL tendon were found.Conclusions: From the study, we conclude that extensor retinaculum thickening is a common finding in de Quervain`s disease

The role of horizontal transfer in the evolution of a highly variable lipopolysaccharide biosynthesis locus in xanthomonads that infect rice, citrus and crucifers

<p>Abstract</p> <p>Background</p> <p>Lipopolysaccharide (LPS) is a pathogen associated molecular pattern (PAMP) of animal and plant pathogenic bacteria. Variation at the interstrain level is common in LPS biosynthetic gene clusters of animal pathogenic bacteria. This variation has been proposed to play a role in evading the host immune system. Even though LPS is a modulator of plant defense responses, reports of interstrain variation in LPS gene clusters of plant pathogenic bacteria are rare.</p> <p>Results</p> <p>In this study we report the complete sequence of a variant 19.9 kb LPS locus present in the BXO8 strain of <it>Xanthomonas oryzae </it>pv. <it>oryzae </it>(Xoo), the bacterial blight pathogen of rice. This region is completely different in size, number and organization of genes from the LPS locus present in most other strains of Xoo from India and Asia. Surprisingly, except for one ORF, all the other ORFs at the BXO8 LPS locus are orthologous to the genes present at this locus in a sequenced strain of <it>X. axonopodis </it>pv. <it>citri </it>(Xac; a pathogen of citrus plants). One end of the BXO8 LPS gene cluster, comprised of ten genes, is also present in the related rice pathogen, <it>X. oryzae </it>pv. <it>oryzicola </it>(Xoc). In Xoc, the remainder of the LPS gene cluster, consisting of seven genes, is novel and unrelated to LPS gene clusters of any of the sequenced xanthomonads. We also report substantial interstrain variation suggestive of very recent horizontal gene transfer (HGT) at the LPS biosynthetic locus of <it>Xanthomonas campestris </it>pv.<it> campestris </it>(Xcc), the black rot pathogen of crucifers.</p> <p>Conclusion</p> <p>Our analyses indicate that HGT has altered the LPS locus during the evolution of <it>Xanthomonas oryzae </it>pathovars and suggest that the ancestor of all <it>Xanthomonas oryzae </it>pathovars had an Xac type of LPS gene cluster. Our finding of interstrain variation in two major xanthomonad pathogens infecting different hosts suggests that the LPS locus in plant pathogenic bacteria, as in animal pathogens, is under intense diversifying selection.</p

Thiodibenzoylmethane as an Extracting & Spectrophotometric Reagent for Bi(III)

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Blade manipulators in turbulent channel flow

We report here the results of a series of careful experiments in turbulent channel flow, using various configurations of blade manipulators suggested as optimal in earlier boundary layer studies. The mass flow in the channel could be held constant to better than 0.1%, and the uncertainties in pressure loss measurements were less than 0.1 mm of water; it was therefore possible to make accurate estimates of the global effects of blade manipulation of a kind that are difficult in boundary layer flows. The flow was fully developed at the station where the blades were mounted, and always relaxed to the same state sufficiently far downstream. It is found that, for a given mass flow, the pressure drop to any station downstream is always higher in the manipulated than in the unmanipulated flow, demonstrating that none of the blade manipulators tried reduces net duct losses. However the net increase in duct losses is less than the drag of the blade even in laminar flow, showing that there is a net reduction in the total skin friction drag experienced by the duct, but this relief is only about 20% of the manipulator drag at most

Screening of tomato (Solanum lycopersicon L.) genotypes by inducing systemic resistance against early blight disease caused by Alternaria solani

Early blight of tomato (Solanum lycopersicon L.) incited by Alternaria solani is highly destructive disease in the world. Environmental factors significantly impact early blight epidemics, leading to the loss of up to 78 per cent of tomato production. Twenty tomato genotypes were used in this study to identify the early blight resistant and susceptible genotypes selected to represent a range of reactions when screened under field conditions. The tomato plants were evaluated for early blight disease by using Per cent Disease Index (PDI). Pusa Uphar (20.18%) and Sankaranti (20.18%) showed resistance to early blight disease among the twenty genotypes. Anaka Kerala (61.25%), Arka Vikas (61.76%), Pusa Rohini (53.65%), Ashoka (50.60%) and Paiyur1 (56.08%) genotypes were found highly susceptible based on early blight disease intensity. Spore inoculation of A. solani was sprayed into tomato plants, it was discovered that the number of defense-inducing compounds viz., total phenols, peroxidase (PO), polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL) has increased. Among the genotypes, Pusa Uphar (T2) and Sankaranti (T1) genotypes showed a high level of defense enzyme production. After tomato plants were exposed to pathogens through artificial inoculation, the activity of these defensive enzymes and compounds was highly induced in the resistant and sensitive germplasm than in the control. 

Variation suggestive of horizontal gene transfer at a lipopolysaccharide (lps) biosynthetic locus in Xanthomonas oryzae pv. oryzae, the bacterial leaf blight pathogen of rice

BACKGROUND: In animal pathogenic bacteria, horizontal gene transfer events (HGT) have been frequently observed in genomic regions that encode functions involved in biosynthesis of the outer membrane located lipopolysaccharide (LPS). As a result, different strains of the same pathogen can have substantially different lps biosynthetic gene clusters. Since LPS is highly antigenic, the variation at lps loci is attributed to be of advantage in evading the host immune system. Although LPS has been suggested as a potentiator of plant defense responses, interstrain variation at lps biosynthetic gene clusters has not been reported for any plant pathogenic bacterium. RESULTS: We report here the complete sequence of a 12.2 kb virulence locus of Xanthomonas oryzae pv. oryzae (Xoo) encoding six genes whose products are homologous to functions involved in LPS biosynthesis and transport. All six open reading frames (ORFs) have atypical G+C content and altered codon usage, which are the hallmarks of genomic islands that are acquired by horizontal gene transfer. The lps locus is flanked by highly conserved genes, metB and etfA, respectively encoding cystathionine gamma lyase and electron transport flavoprotein. Interestingly, two different sets of lps genes are present at this locus in the plant pathogens, Xanthomonas campestris pv. campestris (Xcc) and Xanthomonas axonopodis pv. citri (Xac). The genomic island is present in a number of Xoo strains from India and other Asian countries but is not present in two strains, one from India (BXO8) and another from Nepal (Nepal624) as well as the closely related rice pathogen, Xanthomonas oryzae pv. oryzicola (Xoor). TAIL-PCR analysis indicates that sequences related to Xac are present at the lps locus in both BXO8 and Nepal624. The Xoor strain has a hybrid lps gene cluster, with sequences at the metB and etfA ends, being most closely related to sequences from Xac and the tomato pathogen, Pseudomonas syringae pv. tomato respectively. CONCLUSION: This is the first report of hypervariation at an lps locus between different strains of a plant pathogenic bacterium. Our results indicate that multiple HGT events have occurred at this locus in the xanthomonad group of plant pathogens