Production of biosurfactant “Biosur-Pm” by Pseudomonas maltophila CSV89: characterization and role in hydrocarbon uptake

Pseudomonas maltophilia CSV89, a soil bacterium, produces an extracellular biosurfactant, ''Biosur-Pm''. The partially purified product is nondialyzable and chemically composed of 50% protein and 12-15% sugar, which indicates the complex nature of Biosur-Pm. It reduces the surface tension of water from 73 to 53 x 10(-3) N m(-1) and has a critical micellar concentration of 80 mg/l. Compared to aliphatic hydrocarbons, Biosur-Pm shows good activity against aromatic hydrocarbons. The emulsion formed is stable and does not require any metal ions for emulsification. The kinetics of Biosur-Pm production suggest that its synthesis isa growth-associated and pH-dependent process. At pH 7.0, cells produced more Biosur-Pm with less cell surface hydrophobicity. At pH 8.0, however, the cells produced less Biosur-Pm with more cell surface hydrophobicity and showed a twofold higher affinity for aromatic hydrocarbons compared to the cells grown at pH 7.0. The Biosur-Pm showed a pH-dependent release, stimulated growth of the producer strain on mineral salts medium with 1-naphthoic acid when added externally, and facilitated the conversion of salicylate to catechol. All these results suggest that Biosur-Pm is probably a cell-wall component and helps in hydrocarbon assimilation/uptake.

Density Functional Theoretical Modeling, Electrostatic Surface Potential and Surface Enhanced Raman Spectroscopic Studies on Biosynthesized Silver Nanoparticles: Observation of 400 pM Sensitivity to Explosives

Interaction of adsorbate on charged surfaces, orientation of the analyte on the surface, and surface enhancement aspects have been studied. These aspects have been explored in details to explain the surface-enhanced Raman spectroscopic (SERS) spectra of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (HNIW or CL-20), a well-known explosive, and 2,4,6-trinitrotoluene (TNT) using one-pot synthesis of silver nanoparticles via biosynthetic route using natural precursor extracts of clove and pepper. The biosynthesized silver nanoparticles (bio Ag Nps) have been characterized using UV-vis spectroscopy, scanning electron microscopy and atomic force microscopy. SERS studies conducted using bio Ag Nps on different water insoluble analytes, such as CL-20 and TNT, lead to SERS signals at concentration levels of 400 pM. The experimental findings have been corroborated with density functional computational results, electrostatic surface potential calculations, Fukui functions and potential measurements.

X-Ray Studies On The Bilayer Structure Of Trypsin-Treated Rat-Brain Myelin

Trypsin-treated rat brain myelin was subjected to biochemical and X-ray studies. Untreated myelin gave rise to a pattern of three rings with a fundamental repeat period of 155 Angstrom consisting of two bilayers per repeat period, whereas myelin treated with trypsin showed a fundamental repeat period of 75 Angstrom with one bilayer per repeat period. The integrated raw intensity of the h=4 reflection with respect to the h=2 reflection is 0.38 for untreated myelin. The corresponding value reduced to 0.23, 0.18, 0.17 for myelin treated with 5, 10, 40 units of trypsin per mg of myelin, respectively, for 30 min at 30 degrees C. The decrease in relative raw intensity of the higher-order reflection relative to the lower-order reflection is suggestive of a disordering of the phosphate groups upon trypsin treatment or an increased mosaicity of the membrane or a combination of both these effects, However, trypsin treatment does not lead to a complete breakdown of the membrane, The integrated intensity of the h=1 reflection, though weak, is above the measurable threshold for untreated myelin, whereas the corresponding intensity is below the measurable threshold for trypsin-treated myelin, indicating a possible asymmetric to symmetric transition of the myelin bilayer structure about its centre after trypsin treatment.

Structure of the noncubic phase in the ferroelectric state of Pr-substituted SrTiO3

Sr1−xPrxTiO3 has recently been shown to exhibit ferroelectricity at room temperature. In this paper powder x-ray and neutron-diffraction patterns of this system at room temperature have been analyzed to show that the system exhibits cubic (Pm-3m) structure for x<=0.05 and tetragonal (I4/mcm) for x>0.05. The redundancy of the noncentrosymmetric structural model (I4cm) in the ferroelectric state suggests the absence of long-range ordered ferroelectric domains and supports the relaxor ferroelectric model for this system.

Compiling Techniques for Coarse Grained Runtime Reconfigurable Architectures

In this paper we develop compilation techniques for the realization of applications described in a High Level Language (HLL) onto a Runtime Reconfigurable Architecture. The compiler determines Hyper Operations (HyperOps) that are subgraphs of a data flow graph (of an application) and comprise elementary operations that have strong producer-consumer relationship. These HyperOps are hosted on computation structures that are provisioned on demand at runtime. We also report compiler optimizations that collectively reduce the overheads of data-driven computations in runtime reconfigurable architectures. On an average, HyperOps offer a 44% reduction in total execution time and a 18% reduction in management overheads as compared to using basic blocks as coarse grained operations. We show that HyperOps formed using our compiler are suitable to support data flow software pipelining.

An elementary approach to gap theorems

Using elementary comparison geometry, we prove: Let (M, g) be a simply-connected complete Riemannian manifold of dimension >= 3. Suppose that the sectional curvature K satisfies -1-s(r) <= K <= -1, where r denotes distance to a fixed point in M. If lim(r ->infinity) e(2r) s(r) = 0, then (M, g) has to be isometric to H-n.The same proof also yields that if K satisfies -s(r) <= K <= 0 where lim(r ->infinity) r(2) s(r) = 0, then (M, g) is isometric to R-n, a result due to Greene and Wu.Our second result is a local one: Let (M, g) be any Riemannian manifold. For a E R, if K < a on a geodesic ball Bp (R) in M and K = a on partial derivative B-p (R), then K = a on B-p (R).

Studies of phosphazenes. 12. Reactions of N4P4Cl8 with dibenzylamine- isolation of an unusual "bicyclic" phosphazene, N4P4[N(CH2Ph)2]6(NCH2Ph)

Octachlorocyclotetraphosphazene, N4P4CIa, reacts with dibenzylamine to give the chloro(dibenzy1amino) derivatives, N4P,C18,[N(CH2Ph)2],,, n = 1, 2 (two isomers), and 4 (three isomers). Nongeminal structures have been assigned to these compounds on the basis of ‘H and jlP NMR spectra. The presence of at least two tris(dibenzylamin0) derivatives in some reaction mixtures is also inferred from NMR spectra. Steric effects become important at the tetrakis stage of chlorine replacement, and further substitution by dibenzylamine to give monocyclic tetrameric derivatives does not occur. A “bicyclic” phosphazene, N4P4[N(CH2Ph)2]6(NCHzPh)is, obtained from the reaction of N4P4Claw ith an excess of dibenzylamine in boiling methyl cyanide. The formation of this derivative and its spectroscopic data are discussed.

The role of triplet states in the emission mechanism of polymer light-emitting diodes

The blue emission of polyfluorene (PF)-based light-emitting diodes (LEDs) is known to degrade due to a low-energy green emission, which hitherto has been attributed to oxidative defects. By studying the electroluminescence (EL) from ethyl-hexyl substituted PF LEDs in the presence of oxygen and in an inert atmosphere, and by using trace quantities of paramagnetic impurities (PM) in the polymer, we show that the triplet states play a major role in the low-energy emission mechanism. Our time-dependent many-body studies show a large cross-section for the triplet formation in the EL process in the presence of PM, primarily due to electron-hole recombination processes.

Emissions from India's transport sector: Statewise synthesis

A decentralized emission inventories are prepared for road transport sector of India in order to design and implement suitable technologies and policies for appropriate mitigation measures. Globalization and liberalization policies of the government in 90's have increased the number of road vehicles nearly 92.6% from 1980-1981 to 2003-2004. These vehicles mainly consume non-renewable fossil fuels, and are a major contributor of green house gases, particularly CO2 emission. This paper focuses on the statewise road transport emissions (CO2, CH4, CO, N-x, N2O, SO2, PM and HC) using region specific mass emission factors for each type of vehicles. The country level emissions (CO2, CH4, CO, NOx, N2O, SO2 and NMVOC) are calculated for railways, shipping and airway, based on fuel types. In India, transport sector emits an estimated 258.10 Tg Of CO2, of which 94.5% was contributed by road transport (2003-2004). Among all the states and Union Territories, Maharashtra's contribution is the largest, 28.85 Tg (11.8%) Of CO2, followed by Tamil Nadu 26.41 Tg(10.8%), Gujarat 23.31 Tg(9.6%), Uttar Pradesh 17.42 Tg(7.1%), Rajasthan 15.17 Tg (6.22%) and, Karnataka 15.09 Tg (6.19%). These six states account for 51.8% of the CO2 emissions from road transport.

Epigallocatechin gallate is a slow-tight binding inhibitor of enoyl-ACP reductase from Plasmodium falciparum

Epigallocatechin gallate (EGCG) is known to have numerous pharmacological properties. In the present study, we have shown that EGCG inhibits enoyl–acyl carrier protein reductase of Plasmodium falciparum (PfENR) by following a two-step, slow, tight-binding inhibition mechanism. The association/isomerization rate constant (k5) of the reversible and loose PfENR–EGCG binary complex to a tight [PfENR–EGCG]* or EI* complex was calculated to be 4.0 × 10−2 s−1. The low dissociation rate constant (k6) of the [PfENR–EGCG]* complex confirms the tight-binding nature of EGCG. EGCG inhibited PfENR with the overall inhibition constant (Ki*) of 7.0 ± 0.8 nM. Further, we also studied the effect of triclosan on the inhibitory activity of EGCG. Triclosan lowered the k6 of the EI* complex by 100 times, lowering the overall Ki* of EGCG to 97.5 ± 12.5 pM. The results support EGCG as a promising candidate for the development of tea catechin based antimalarial drugs.

Chain structures in alkali metal borophosphates: synthesis and characterization of K3[BP3O9(OH)3] and Rb3[B2P3O11(OH)2]

Two new alkali metal borophosphates, K-3[BP(3)o(9)(OH)(3)] and Rb-3[B2P3O11(OH)(2)], were synthesized by applying solvothermal techniques using ethanol as solvent. The crystal structures were solved by means of single-crystal X-ray diffraction (K-3[BP3O9(OH)(3)], monoclinic, C2/c (No. 15), a = 2454.6(8) pm, b = 736.3(2) pm, c = 1406.2(4) pm, beta = 118.35(2)degrees, Z = 8; Rb-3[B2P3O11(OH)(2)], monoclinic, P2(1)/c (No. 14), a = 781.6(2) pm, b:= 667.3(2) pm, c = 2424.8(5) pm, beta = 92.88(1)degrees, Z = 4). Both crystal structures comprise borophosphate chain anions. While for the rubidium compound a loop-branched chain motif is found as common for most of the chain anions in alkali metal borophosphates, the crystal structure of the potassium phase comprises the first open-branched chain with the highest phosphate content found so far in this group of compounds. Both chain anions are Closely related to known anhydrous or hydrated phases, and the structural relations are discussed in terms of how the presence of OH groups and hydrogen bonds as well as number, charge, and size of charge balancing cations influence the 3D structural arrangement. The anionic entities are classified in terms of general principles of structural systematics for borophosphates.

Folding a Polymer via Two-Point Interaction with an External Folding Agent: Use of H-Bonding and Charge-Transfer Interactions

A polymer containing electron-rich aromatic donors (1,5-dialkoxynaphthalene (DAN)) was coerced into a folded state by an external folding agent that contained an electron-deficient aromatic acceptor (pyromellitic diimide (PM)) unit. The donor-containing polymer was designed to carry a tertiary amine moiety in the linking segment, which served as an H-bonding site for reinforcing the interaction with the acceptor containing folding agent that also bore a carboxylic acid group. The H-bonding interaction of the carboxylic acid and the tertiary amine brings the PDI unit between two adjacent DAN units along the polymer backbone to induce charge-transfer (C-T) interactions, and this in turn causes the polymer chain to form a pleated structure. Evidence for the formation of such a pleated structure was obtained from NMR titration studies and also by monitoring the C-T band in their UV-visible spectra. By varying the length of the segment that links the PDI acceptor to the carboxylic acid group, we showed that the most effective folding agent was the one that had a single carbon spacer, as evident from the highest value of the association constant. Control experiments with propionic acid clearly demonstrated the importance of the additional C-T interactions for venerating the folded structures. Further, solution viscosity measurements in the presence of varying amounts of the folding agent revealed a gradual stiffening of the chain in the case of the PDI carrying carboxylic acid, whereas no such affect was seen in the case of simple propionic acid. These observations were supported by D FT calculations of the interactions of a dimeric model of the polymer with the various folding agents; here too the stability of the complex was seen to be highest in the case of the single carbon spacer.

Analysis of network architectures for zigbee sensor clusters

We provide a comparative performance analysis of network architectures for beacon enabled Zigbee sensor clusters using the CSMA/CA MAC defined in the IEEE 802.15.4 standard, and organised as (i) a star topology, and (ii) a two-hop topology. We provide analytical models for obtaining performance measures such as mean network delay, and mean node lifetime. We find that the star topology is substantially superior both in delay performance and lifetime performance than the two-hop topology.

Direct somatic embryogenesis in zygotic embryos of nutmeg (Myristica fragrans Houtt.)

Direct somatic embryogenesis from isolated intact as well as broken zygotic embryos and in vitro plantlets of nutmeg (Myristica fragrans Houtt.) was obtained. Enhanced embryogenic response was associated with broken zygotic embryos. Activated charcoal and light were the critical factors for induction of somatic embryogenesis in nutmeg. Histological evaluation revealed the presence of globular and cotyledonary stages. The somatic embryos underwent partial germination after a six-month lag period. A wide range of abnormal embryos were observed. The somatic embryos synthesised chlorophyll, exhibited phenylalanine ammonia lyase activity, synthesised phenolics, and could serve as a stable source of secondary metabolites of nutmeg which are commercially important.

Sorghum proteinase inhibitors: purification and some biochemical properties

An investigation has been carried out on the proteinase inhibitors of grain sorghum (Sorghum bicolor (L.) Moench). One of the inhibitors has been isolated in a pure form and characterized. The proteinase inhibitor was extracted from the acetone-defatted sorghum meal and purified by selective thermal denaturation, ammonium sulfate fractionation, Sephadex gel filtration and DEAE-cellulose chromatography (DEAE-preparation II). This preparation was demonstrated to be a mixture of three inhibitor components by polyacrylamide disc gel electrophoresis. Further resolution of this mixture into Inhibitors I to III was achieved by QAE-Sephadex chromatography. Sorghum Inhibitor III was homogeneous by the criteria of disc gel electrophoresis and has been more fully characterized. A molecular weight of 25,000 was obtained for Inhibitor III by gel filtration and was in agreement with the value calculated from the amino acid composition of the inhibitor. The N-terminal amino acid residue of Inhibitor III, a single chain protein, was isoleucine. Sorghum proteinase inhibitors inhibit specifically the serine proteinases and are inactive towards the other classes of proteinases. Inhibitor III is primarily a chymotrypsin inhibitor, whereas Inhibitors I and II inhibit both trypsin and chymotrypsin.