Comparative genomics reveals `novel' Fur regulated sRNAs and coding genes in diverse proteobacteria

Ferric uptake regulator (Fur) is a transcriptional regulator controlling the expression of genes involved in iron homeostasis and plays an important role in pathogenesis. Fur-regulated sRNAs/CDSs were found to have upstream Fur Binding Sites (FBS). We have constructed a Positional Weight Matrix from 100 known FBS (19 nt) and tracked the `Orphan' FBSs. Possible Fur regulated sRNAs and CDSs were identified by comparing their genomic locations with the `Orphan' FBSs identified. Thirty-eight `novel' and all known Fur regulated sRNAs in nine proteobacteria were identified. In addition, we identified high scoring FBSs in the promoter regions of the 304 CDSs and 68 of them were involved in siderophore biosynthesis, iron-transporters, two-component system, starch/sugar metabolism, sulphur/methane metabolism, etc. The present study shows that the Fur regulator controls the expression of genes involved in diverse metabolic activities and it is not limited to iron metabolism alone. (C) 2012 Elsevier B.V. All rights reserved.

The effect of minor addition of Ni on the microstructural evolution and mechanical properties of suction cast Al-0.14 at. pct Sc binary alloy

Aluminum scandium binary alloys represent a promising precipitation-hardening alloy system. However, the hardness of the binary alloys decreases with the rapid coarsening of Al3Sc precipitate during high-temperature aging. In the current study, we report a new approach to compensate for the loss of mechanical properties by combining rapid solidification with very small ternary addition of transition metal Ni. This addition yields dispersion, and at a critical concentration improves the mechanical properties. We explore additions of a maximum of 0.06 at. pct of Nickel to a binary Al-0.14 at. pct Sc alloy, which yield nickel-rich dispersions. We report two kinds of biphasic dispersions containing AlNi2Sc/Al9Ni2 and alpha-Al/Al9Ni2 phase combinations. The maximum improvement in mechanical properties occurs with the addition of 0.045 at. pct Ni with a yield strength of 239 +/- A 7 MPa for an aging treatment at 583 K (310 A degrees C) for 15 hours. DOI: 10.1007/s11661-013-1624-z (C) The Minerals, Metals & Materials Society and ASM International 2013

Effect of indium addition on microstructural, mechanical and oxidation properties of suction cast Nb-Si eutectic alloy

The paper reports effect of small ternary addition of In on the microstructure, mechanical property and oxidation behaviour of a near eutectic suction cast Nb-19.1 at-%Si-1.5 at-%In alloy. The observed microstructure consists of a combination of two kinds of lamellar structure. They are metal-intermetallic combinations of Nb-ss-beta-Nb5Si3 and Nb-ss-alpha-Nb5Si3 respectively having 40-60 nm lamellar spacings. The alloy gives compressive strength of 3 GPa and engineering strain of similar to 3% at room temperature. The composite structure also exhibits a large improvement in oxidation resistance at high temperature (1000 degrees C).

Diverse functions of restriction-modification systems in addition to cellular defense

Restriction-modification (R-M) systems are ubiquitous and are often considered primitive immune systems in bacteria. Their diversity and prevalence across the prokaryotic kingdom are an indication of their success as a defense mechanism against invading genomes. However, their cellular defense function does not adequately explain the basis for their immaculate specificity in sequence recognition and nonuniform distribution, ranging from none to too many, in diverse species. The present review deals with new developments which provide insights into the roles of these enzymes in other aspects of cellular function. In this review, emphasis is placed on novel hypotheses and various findings that have not yet been dealt with in a critical review. Emerging studies indicate their role in various cellular processes other than host defense, virulence, and even controlling the rate of evolution of the organism. We also discuss how R-M systems could have successfully evolved and be involved in additional cellular portfolios, thereby increasing the relative fitness of their hosts in the population.

Catalytic Asymmetric Direct Vinylogous Michael Addition of gamma-Aryl-Substituted Deconjugated Butenolides to Nitroolefins and N-Phenylmaleimide

Direct asymmetric vinylogous Michael reactions of gamma-aryl-substituted deconjugated butenolides with nitroolefins and N-phenylmaleimide are described using bifunctional thiourea derivatives as the catalyst. The resulting butenolide derivatives containing adjacent quaternary and tertiary stereocenters are obtained in good yields (54-90%) and with excellent enantioselectivities (er up to 99:1) and high diastereoselectivities (dr up to > 20:1).

Facial selectivities in the nucleophilic additions of 2,3-unsaturated 3-arylsulfinyl pyranosides

2,3-Unsaturated 3-arylsulfinyl pyranosides undergo nucleophilic additions at C-2, with facial selectivities depending on the nucleophile and the substituent on sulfinyl sulfur. The reactions of such sugar vinyl sulfoxides lead to the addition of nucleophile preferring an axial orientation at C-2, with concomitant formation of an allylic bond at C-3 to C-4. This trend in the addition pattern is observed for primary amine, carbon and sulfur nucleophiles, whereas secondary amines prefer an equatorial addition at C-2. The effect of p-tolylthio-versus (p-isopropylphenyl)thio vinyl sulfoxide is that the equatorial nucleophilic addition is preferred even more with the latter vinyl sulfoxide. (C) 2013 Published by Elsevier Ltd.

Synergistic Lewis base and anion-binding catalysis for the enantioselective vinylogous addition of deconjugated butenolides to allenoates

An enantioselective vinylogous umpolung addition of deconjugated butenolides to allenoates has been developed for the first time with the help of synergistic combination of an achiral phosphine and a chiral squaramide, and represents the first example of a catalytic enantioselective C gamma-C gamma bond formation between two different carbonyl partners.

Effect of the Addition of B2O3 on the Density, Microstructure, Dielectric, Piezoelectric and Ferroelectric Properties of K0.5Na0.5NbO3 Ceramics

Boron oxide (B2O3) addition to pre-reacted K0.5Na0.5NbO3 (KNN) powders facilitated swift densification at relatively low sintering temperatures which was believed to be a key to minimize potassium and sodium loss. The base KNN powder was synthesized via solid-state reaction route. The different amounts (0.1-1 wt%) of B2O3 were-added, and ceramics were sintered at different temperatures and durations to optimize the amount of B2O3 needed to obtain KNN pellets with highest possible density and grain size. The 0.1 wt% B2O3-added KNN ceramics sintered at 1,100 A degrees C for 1 h exhibited higher density (97 %). Scanning electron microscopy studies confirmed an increase in average grain size with increasing B2O3 content at appropriate temperature of sintering and duration. The B2O3-added KNN ceramics exhibited improved dielectric and piezoelectric properties at room temperature. For instance, 0.1 wt% B2O3-added KNN ceramic exhibited d (33) value of 116 pC/N which is much higher than that of pure KNN ceramics. Interestingly, all the B2O3-added (0.1-1 wt%) KNN ceramics exhibited polarization-electric field (P vs. E) hysteresis loops at room temperature. The remnant polarization (P (r)) and coercive field (E (c)) values are dependent on the B2O3 content and crystallite size.

Effect of nanoscale boron carbide particle addition on the microstructural evolution and mechanical response of pure magnesium

In this study, the effect of nano-B4C addition on the microstructural and the mechanical behavior of pure Mg are investigated. Pure Mg-metal reinforced with different amounts of nano-size B4C particulates were synthesized using the disintegrated melt deposition technique followed by hot extrusion. Microstructural characterization of the developed Mg/x-B4C composites revealed uniform distribution of nano-B4C particulates and significant grain refinement. Electron back scattered diffraction (EBSD) analyses showed presence of relatively more recrystallized grains and absence of fiber texture in Mg/B4C nanocomposites when compared to pure Mg. The evaluation of mechanical properties indicated a significant improvement in tensile properties of the composites. The significant improvement in tensile ductility (similar to 180% increase with respect to pure Mg) is among the highest observed when compared to the pure Mg based nanocomposites existing in the current literature. The superior mechanical properties of the Mg/B4C nanocomposites are attributed to the uniform distribution of the nanoparticles and the tendency for texture randomization (absence of fiber texture) achieved due to the nano-B4C addition. (C) 2013 Elsevier Ltd. All rights reserved.

Enhancement in creep resistance of Ti-6Al-4V alloy due to boron addition

The addition of B, up to about 0.1 wt%, to Ti-6Al-4V (Ti64) reduces its as-cast grain and colony sizes by an order of magnitude. In this paper, the creep resistance of this alloy modified with 0.06 and 0.11 wt% B additions was investigated in the temperature range of 475-550 degrees C and compared with that of the base alloy. Conventional dead-weight creep tests as well as stress relaxation tests were employed for this purpose. Experimental results show that the B addition enhances both elevated temperature strength and creep properties of Ti64, especially at the lower end of the temperatures investigated. The steady state creep rate in the alloy with 0.11 wt% B was found to be an order of magnitude lower than that in the base alloy, and both the strain at failure as well as the time for rupture increases with the B content. These marked improvements in the creep resistance due to B addition to Ti64 were attributed primarily to the increased number of inter-phase interfaces - a direct consequence of the microstructural refinement that occurs with the B addition - that provide resistance to dislocation motion. (C) 2014 Elsevier B.V. All rights reserved.

The knight of sugar industry: T. S. Venkatraman (1884-1963)

Tiruvadi Sambasiva Venkatraman (TSV) was a plant breeder. In response to a call from Pundit Madan Mohan Malaviya, he made it his mission to develop high-yielding varieties of sugarcane for manufacturing sugar and making it available as a sweetening agent and an energy source for the malnourished children of India. Using Saccharum officinarum, then under cultivation in India, as the female parent, he artificially fertilized it with pollen from S. barberi, which grew wild in Coimbatore. After 4-5 recurrent backcrossings of S. officinarum Chi wild Sorghum spontaneum with S. officinarum as the female parent, TSV selected the `rare' interspecies hybrid cane varieties that resembled sugarcane and had approximately 2.5 cm thick juicy stems containing 16-18% sucrose - nearly 35 times more than what occurred in parent stocks. The hybrid canes matured quickly, were resistant to waterlogging, drought, and to the red-rot disease caused by Glomerella tucumanensis (Sordariomycetes: Glomerellaceae), and to the sereh-virus disease. Most importantly, they were amenable for propagation using stem cuttings. In recognition of the development of high-yielding sugarcane varieties, TSV was conferred the titles Rao Bahadur, Rao Sahib, and Sir by the British Government, and Padma Bhushan by the Republic of India. In the next few decades, consequent to TSV's work, India turned into the second largest sugar producer in the world, after Brazil. The hybrid sugarcane varieties developed are the foundational stocks for new sugarcane x bamboo hybrids, and for possible resistance to Puccinia megalocephala (Pucciniomycetes: Pucciniaceae) and Ustilago scitaminea (Ustilaginomycetes: Ustilaginaceae) using molecular techniques.

Effect of boron addition and processing of Ti-6Al-4V on corrosion behaviour and biocompatibility

Ti-6Al-4V is widely used to prepare biomedical implant for orthopaedic and dental applications, but it is an expensive choice relative to other implant materials such as stainless steels and Co-Cr alloys, in large part due to the high manufacturing cost. Adding boron to refine the as cast microstructure of Ti-6Al-4V can eliminate the need for extensive hot working and thereby reduce processing costs. The effect of 0.1 wt-% boron addition and the choice of processing route (forging or extrusion) was studied in the context of potential biomedical applications. Corrosion tests in simulated body fluid indicated that the presence of boron increased the corrosion rate of Ti-6Al-4V and that the increase was higher for forged alloys than for extruded alloys. Boron addition and processing route were found to have a minimal effect on the viability of osteoblasts on the alloy surfaces. It is concluded that the addition of boron could offer advantages during the processing of Ti-6Al-4V for biomedical applications.

Low-Density Steels: The Effect of Al Addition on Microstructure and Properties

Density reduction of automotive steels is needed to reduce fuel consumption, thereby reducing greenhouse gas emissions. Aluminum addition has been found to be effective in making steels lighter. Such an addition does not change the crystal structure of the material. Steels modified with aluminum possess higher strength with very little compromise in ductility. In this work, different compositions of Fe-Al systems have been studied so that the desired properties of the material remain within the limit. A density reduction of approximately 10% has been achieved. The specific strength of optimal Fe-Al alloys is higher than conventional steels such as ultra-low-carbon steels.

beta gamma-fused turn structures in sugar amino acid (SAA) containing cyclic tetrapeptides with alpha 3 delta architecture

The current manuscript describes conformational analysis of 15-membered cyclic tetrapeptides (CTPs), with alpha 3 delta architecture, containing sugar amino acids (SAA) having variation in the stereocenter at C5 carbon. Conformational analyses of both the series, in protected and deprotected forms, were carried out in DMSO-d(6) using various NMR techniques, supported by restrained MD calculations. It was intriguing to notice that the alpha 3 delta macrocycles got stabilized by both 10-membered beta-turn as well as a seven-membered gamma-turn, fused within the same macrocycle. The presence of fused sub-structures within a 15-membered macrocycle is rare to see. Also, the stereocenter variation at C5 did not affect the fused turn structures and exhibited similar conformations in both the series. The design becomes highly advantageous as fused reverse turn structures are occurring in the cyclic structure with minimalistic size macrocycle and this can be applied to develop suitable pharmacophores in the drug development process. (C) 2014 Elsevier Ltd. All rights reserved.

Nano-ZnO particle addition to monolithic magnesium for enhanced tensile and compressive response

In this study, the effects of nanoscale ZnO reinforcement on the room temperature tensile and compressive response of monolithic Mg were studied. Experimental observations indicated strength properties improvement due to nanoscale ZnO addition. A maximum increment in tensile yield strength by similar to 55% and compressive yield strength by 90% (with reduced tension-compression asymmetry) was achieved when 0.8 vol.% ZnO nanoparticles were added to Mg. While the fracture strain values under tensile loads were found to increase significantly (by similar to 95%, in case of Mg-0.48ZnO), it remained largely unaffected under compressive loads. The microstructural characteristics studied in order to comprehend the mechanical response showed significant grain refinement due to grain boundary pinning effect of nano-ZnO particles which resulted in strengthening of Mg. Texture analysis using X-ray and EBSD methods indicated weakening of basal fibre texture in Mg/ZnO nanocomposites which contributed towards the reduction in tension-compression yield asymmetry and enhancement in tensile ductility when compared to pure Mg. (C) 2014 Elsevier B.V. All rights reserved.