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Twenty F1 s, parents and checks viz., MTU 1010 and RNR 15048 were assessed for grain yield and its contributing attributes to study combining ability and heterosis. The mean of hybrids was greater than that of the parents except for days to 50% flowering and plant height. For majority of the investigated characters, the analysis of variance indicated considerable variations among parents and hybrids. Degree of dominance was more than unity for majority of traits including grain yield. For the examined characters, SCA variances were equal to GCA variances, indicating the dominance of additive and non-additive gene activity. The traits days to 50 % flowering, plant height, panicle length, test weight, kernel length and kernel length/breadth ratio showed additive gene action whereas the remaining traits showed non-additive gene action. The gca effects revealed that among the lines IR 72 had significant gca effects in desired direction for yield and yield attributing traits. Among the 20 hybrids, MTU 1001 x Akshyadhan was found to be a good specific combiner for grain yield per plant. Similarly, the hybrids NLR 34449 x IR10N270 and IR 72 x IR10N270 were found to be good specific combiners for grain yield and yield contributing characters. The standard heterosis of these three hybrids was positively significant over the check varieties MTU 1010 and RNR 15048. Based on mean, sca and heterosis estimates, MTU 1001 x Akshyadhan, NLR 34449 x IR10N270 and IR 72 x IR10N270 were identified as promising hybrids. [ABSTRACT FROM AUTHOR]

Herein, the nanoparticles of SrTiO3perovskite oxide were synthesized using simple hydrothermal process. The synthesized perovskite oxide material was characterized by XRD and FTIR techniques. The XRD analysis reveals that the formed SrTiO3 perovskite oxide in cubic crystal phase with high phase purity. The FTIR result demonstrate the stretching and vibration bands of Ti-O and Sr-O along with O-H functional groups. The SrTiO3perovskite oxide powder was added to silicone resin and the paste was applied on AZ31 alloy sample, which was then used for electrochemical analysis. The corrosion characteristics of SrTiO3perovskite oxide coating over AZ31 alloy were investigated in 7 % NaCl electrolyte, wherein platinum foil used as counter electrode, saturated calomel electrode (SCE) as reference and SrTiO3perovskite oxide coated AZ31 alloy as working electrode. The results reveal that the open circuit potential of AZ31 alloy shifted from -1.57 V (SCE) to -0.95 V (SCE). The corrosion rates of bare AZ31 alloy calculated and found as 7 x 10-2 mA/cm2, while the same after coating was measured as 9 x 10-6 mA/cm2. The electrochemical impedance results also reveal that corrosion protection induced by the coating. Hence, it is summarized that the SrTiO3perovskite oxide coating demonstrated improved corrosion resistance for AZ31 alloy. [ABSTRACT FROM AUTHOR]

An investigation was conducted with 217 germplasm lines of rice to estimate potential variation among rice genotypes. Multivariate analyses viz., PCA and cluster analysis to assess genetic diversity were performed on seven agronomic traits. For the evaluated traits in the lines of germplasm, box plots and normal probability plots displayed substantial estimates of variability. PCA showed that PC1 and PC2 represented 46.15 per cent of variation. PC1 was responsible for the most variance (24%) for four characters, followed by PC2 (22.15%) for three parameters. Filled grain number per panicle, single plant yield, plant height and thousand grain weight were identified as vital traits contributing to variability. Based on agglomerative hierarchical cluster analysis, the germplasm lines were grouped into five clusters, which explained a lot of variation in the traits. The study identified that plant height and 1000 grain weight have the greatest impact on variation. The genotypes viz., WGL 1063, RNR 26085, OR 2511-3, Swarna, KNM 7123, WGL 1063, MGD-101, IVT MS-6130, IVT IM-4231, IVT IME-3948 and IVT NPT-6303 were found to be the best performing genotypes for the traits panicle length, plant height and single plant yield, which can be used in hybridisation programme to improve these traits. [ABSTRACT FROM AUTHOR]

An investigation was carried out on fifteen rice genotypes to identify stable rice hybrids across six different agroclimatic zones in Telangana state using AMMI and GGE bi-plot analyses during July to November, 2020. Analysis of variance clearly showed that environments contributed highest (65.47%) in total sum of squares followed by genotypes×environments (21.19%) indicating very greater role played by environments and their interactions in realizing final grain yield. AMMI analysis revealed that rice hybrids viz., RNRH 39 (G6), 27P31 (G14) and RNRH 15 (G1) were recorded higher mean grain yield with positive IPCA1 scores. The hybrids, JGLH 275 (G11) and JGLH 365 (G15) were plotted near to zero IPCA1 axis indicating that these hybrids are relatively more stable across locations. GGE bi-plot genotype view depicts that the hybrids, JGLH 365 (G15) and US 314 (G8) were inside the first concentric circle and found to be more stable across environments. GGE bi-plot environment view showed that Rudrur (E4) location was the most ideal environment. However, Warangal (E6) and Jagtial (E1) locations were poor and most discriminating. Depending on dispersion of environments in different directions, six locations were partitioned into three mega zones as first zone comprised of four locations viz., Kunaram (E2), Kampasagar (E3), Rudrur (E4) and Rajendranagar (E5) whereas highly dispersed Jagtial (E1) and Warangal (E6) were identified as two separate mega environments. The bi-plot view identified that 27P31 (G14), JGL 24423 (G2) and RNRH 39 (G6) were the best performing genotypes in first zone comprising four locations. [ABSTRACT FROM AUTHOR]

The knowledge of genetic variability in a given crop species for characters under improvement is important in any plant breeding programme. Genetic parameters for yield and its correspondent characters in rice were estimated from a trial conducted at Rice Research Centre, Agricultural Research Institute, PJTSAU, Hyderabad during Kharif, 2017. In the present study, four Cytoplasmic Male Sterility lines, eight male lines and thirty-two hybrids and four checks were evaluated. The analysis of variance showed highly significant differences among the genotypes for all the characters, indicated the presence of enormous amount of genetic variability. High phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) was observed for number of grains per panicle (26.55, 23.16) and grain yield per plant (21.67, 21.24) indicating that these characters could use as selection for crop improvement. High heritability coupled with high genetic gain as percentage of mean was observed for number of grains per panicle (70.26, 41.61) and 1000 grain weight (61.9, 29.52) which showed presence of additive gene action and thus the chances of fixing by selection will be more to improve such traits through pure line selection in the evaluated genotypes. [ABSTRACT FROM AUTHOR]

1-3 type piezocomposites are very attractive materials for transducers and biomedical application, due to its high electromechanical coupling effects. Reliability study on 1-3 piezocomposites subjected to cyclic loading condition in transducer application is one of the primary concern. Hence, this study focuses on 1-3 piezocomposites for various PZT5A1 fiber volume fraction subjected to electrical fatigue loading up-to 106 cycles and at various elevated temperature. Initially experiments are performed on 1-3 piezocomposites, in order to understand the degradation phenomena due to various range in amplitude of electric fields (unipolar & bipolar), frequency of applied electric field and for various ambient temperature. Performing experiments for high cycle fatigue and for different fiber volume fraction of PZT5A1 is a time consuming process. Hence, a simplified macroscopic uni-axial model based on physical mechanisms of domain switching and continuum damage mechanics has been developed to predict the non-linear fatigue behaviour of 1-3 piezocomposites for temperature dependent electrical fatigue loading conditions. In this model, damage effects namely domain pinning, frozen domains and micro cracks, are considered as a damage variable (ω). Remnant variables and material properties are considered as a function of internal damage variable and the growth of the damage is derived empirically based on the experimental observation to predict the macroscopic changes in the properties. The measured material properties and dielectric hysteresis (electric displacement vs. electric field) as well as butterfly curves (longitudinal strain vs. electric field) are compared with the simulated results. It is observed that variation in amplitude of bipolar electric field and temperature has a strong influence on the response of 1-3 piezocomposites. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) is one of the most important food crops and a primary source of food for more than half the world's population. Gall midge is an important pest especially during rainy season with delayed sowings resulting in huge losses to the farm produce. Host plant resistance is proven method for enabling protection from gall midge incidence. Use of diverse parents and knowing inheritance of traits helps breeders to develop new varieties. Fortythree genotypes derived through pedigree method of breeding involving 11 divergent parents were evaluated for variability and genetic divergence. The GCV and PCV were high for gall midge incidence, number of grains per panicle and test weight whereas low for panicle length, plant height, effective bearing tillers per hill, days to flowering. High to moderate values of heritability and genetic advance were observed for test weight, number of grains per panicle revealed the predominance of additive gene effects. Grain yield recorded significantly positive correlation with plant height, test weight and days to flowering. Test weight had significant positive correlations with gall midge incidence indicating fine grain varieties were relatively tolerant and bold grain varieties were susceptible. Path analysis revealed that maximum direct effect on grain yield was exhibited by test weight followed by plant height, number of grains per panicle. D2 studies revealed that highest inter cluster distance (8.69) was observed between cluster II & V followed by cluster II & III (7.87) suggesting wide diversity between traits. Among the traits studied, test weight and days to flowering contributed highest. The genotypes grouped in cluster II could be crossed with JGL 21002 and JGL 21005 of cluster III to derive transgressive segregants for improvement of grain yield, number of grains per panicle and test weight. [ABSTRACT FROM AUTHOR]

An experiment was conducted at the Agricultural College, Aswaraopet, Bhadradri Kothagudem district, Telangana, India during July to December 2021 by using thirty elite rice genotypes comprising of different durations i.e. short, medium and long to study the nature of relationship between grain yield and morpho-physiological traits by partitioning the correlation co-efficients between grain yield and morpho-physiological traits into direct and indirect effects. Observations were recorded on seven yield, six physiological and three root characters. The correlation studies revealed that, grain yield plant-1 had shown a significant positive association with yield contributing traits like 1000 grain weight, spikelet fertility, specific leaf area and root biomass, indicating the importance of these traits in yield improvement. Among all other yield attributing characters, spikelet fertility showed the highest significant positive correlation with yield whereas days to 50% flowering and number of productive tillers plant-1 exhibited non-significant positive association with grain yield plant-1. Path coefficient analysis revealed that the highest positive direct effect on grain yield was exhibited by spikelet fertility and 1000 grain weight. A high magnitude of negative direct effects on yield was shown by field emergence at 14 DAS. Thus, from the studies on correlation and path analysis, it could be concluded that the traits viz., spikelet fertility, 1000 grain weight, specific leaf area and root biomass could be used as selection parameters for improving grain yield under dry DSR system. [ABSTRACT FROM AUTHOR]

In the current study, 20 elite rice genotypes were crossed with four CMS lines-CMS 23A, CMS 59A, CMS 64A and JMS 13A in a line x tester mating design and assessed alongside standard controls (JKRH 3333 and MTU 1001) to determine the best heterotic combinations in terms of grain yield and yield component characters at the Rice Research Centre, Rajendranagar. Eight restorer lines were found in Kharif 2018-19 based on pollen and spikelet fertility (MTU 1153, RNR 26015, RNR 28355, JGL 25960, MTU 1010, IET 27253, RNR 26085 and JAYA). The resulting 32 hybrids of 8 restorer lines and their corresponding CMS lines are studied for combing ability and heterosis. The degree of heterosis varied between traits. Three of the 32 hybrids under study had considerable standard heterosis for grain yield viz., JMS 13A x MTU 1153, CMS 59A x RNR 26015 and CMS 64A x MTU 1153, which outperformed the best checks JKRH 3333 and MTU 1001. The best experimental hybrid, JMS 13A x MTU 1153, yielded the most grain yield per plant, 62.89g (Table 1). Further testing of these three experimental hybrids will take place in areas conducive to extensive commercialization. [ABSTRACT FROM AUTHOR]

Selective anionic polymerization of 4-vinylbenzyl methacrylateat methacrylate site has been achieved using resonance stabilizedanionic initiators such as 1,1-diphenylhexyllithium (DPHLi) and tritylpotassium(TritylK) in tetrahydrofuran (THF) at −78 °C. Polymerizationproceeded selectively through methacrylate functionality of the monomerin a controlled manner and produced polymers and copolymers with narrowmolecular weight distribution at low temperatures (≤−40°C). 1H NMR of the polymer showed the presence ofstyrene pendants in every monomeric repeating unit. The polymerizationresults confirm that the resonance stabilized carbanions with an optimumpKa(30 ≤ pKa≤ 32) of their conjugate acids such as DPHLi and TritylKdo not react with styrene functionality at −78 °C. Theselective initiation without cross-linking is attributed to the differencesin the electronegativity between polar methacrylate and styrene functionalitiesand an attenuation of initiator reactivity at low temperature. Poly(4-vinylbenzylmethacrylate) and its copolymers with the vinyl pendant in close proximitywith ester linkage are very reactive and unstable, readily undergoingcross-linking in solution or in solid state with or without a radicalinitiator. [ABSTRACT FROM AUTHOR]

Abstract: In the present investigation the antimicrobial efficiency of cotton fibres loaded with silver nanoparticles (AgNPs) was studied which are developed by “green process” using natural extracts, of Eucalyptus citriodora and Ficus bengalensis. The formation of AgNPs on the cotton fibres was observed by UV–vis spectrophotometer. The size of silver nanoparticles was found to have ∼20nm. The structure and morphology of silver nanoparticles formed on the cotton fibres were confirmed by electron microscopy. The antibacterial activity of cotton fibres loaded with silver nanoparticles was evaluated against gram-negative Escherichia coli (E. coli) bacteria. The results suggest excellent antibacterial activity by the incorporation of 2% leaf extracts on cotton fibres. These fibres have also exhibited superior antibacterial activity even after several washings indicating their usage in medical and infection prevention applications. [ABSTRACT FROM AUTHOR]

Abstract: The present investigation involves the synthesis of porous chitosan–silver nanocomposite films in view of their increasing areas of application in wound dressing, antibacterial application, and water purification. The entire process consists of three-steps including silver ion-poly(ethylene glycol) matrix preparation, addition of chitosan matrix, and removal of poly(ethylene glycol) from the film matrix. Uniform porous and brown colour chitosan films impregnated with silver nanoparticles (AgNPs) were successfully fabricated by this facile approach. Both, poly(ethylene glycol) (PEG) and chitosan (CS) played vital roles in the reduction of metal ions into nanoparticles (NPs) as well as provided good stability to the formed nanoparticles. The developed porous chitosan–silver nanocomposite (PCSSNC) films were characterized by UV–vis and FTIR spectroscopy, and thermogravimetric analysis for the confirmation of nanoparticles formation. The morphology of silver nanoparticles in nanocomposite films was tested by optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The embedded AgNPs were clearly observed throughout the film in SEM and the extracted AgNPs from the porous chitosan–silver nanocomposite showed ∼12nm in TEM. Improved mechanical properties were observed for porous chitosan–silver nanocomposite than for chitosan blend (CSB) and chitosan–silver nanocomposite (CSSNC) films. Further, the examined antibacterial activity results of these films revealed that porous chitosan–silver nanocomposite films exhibited superior inhibition. [Copyright &y& Elsevier]

Abstract: Silver nanoparticles are the most widely used antibacterial agents with a number of advantages. The higher degree of biocompatibility and long-term antibacterial activity can be achieved with hydrogel–silver nanoparticles. In this work, a simple and facile synthetic strategy is developed to control the size and shape of the silver nanoparticles within the hydrogel networks. The variation in cross-link density of the polymer network has been found not only to control the size of the nanoparticles between 1 and 10nm, but it also regulates shape of the nanostructures such as nanorods, nanocubes, etc. This approach takes the advantage of the existing free-space between the networks of hydrogels that not only acts as a template for nucleation of particles but also provides long term stability. Further, nanoparticles can be recovered at any time from the hydrogel networks. These hybrid nanocomposites release nanoparticles with time which can eventually promote for antibacterial application. It can be inferred from the study that fine tuning of the hydrogel synthetic parameters will enhance the possibilities of desired nano-product tailor made for particular applications. [Copyright &y& Elsevier]

Recent advances in drug delivery have been directed towards the design of a number of intelligent systems for the treatment of various diseases. In this regard, we developed novel surfactant-modified hydrogels which are synthesized from acrylamide (AM) and acrylamido propane sulphonic acid (AMPS), in the presence of a surfactant (Latemul PD-104) using ammonium persulfate/N,N,N',N'-tetramethylethylene diamine (APS)/(TMEDA) as an initiating system and N,N'-methylenebisacrlyamide (MBA) as a crosslinker. The hydrogel formation was confirmed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The variation in the hydrogel networks formation employing different levels of synthetic parameters was verified by swelling studies. Influences of salt, biological fluids, and buffer solutions on the developed systems were also investigated. It was found that, compared to PAM hydrogel, all the surfactant-modified hydrogels were responsive towards salt concentration and pH. A robust drug release behavior was observed from surfactant-modified hydrogel systems. [ABSTRACT FROM AUTHOR]

Abstract: Semi-IPN hydrogels in which poly(vinyl pyrrolidone) (PVP) chains were physically dispersed throughout poly(acrylamide) (PAM) gel networks were synthesized. These semi-IPN hydrogel networks can act as excellent nanoreactors for producing and stabilizing metal nanoparticles. The current methodology allows us to entrap metal nanoparticles throughout hydrogel networks via PVP chains. An optimized semi-IPN hydrogel formulation was found to produce silver nanoparticles, ca. 3–5 nm. The synthesized semi-IPN hydrogel–silver nanocomposites were fully characterized by using UV–vis, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The developed semi-IPN hydrogel–silver nanocomposite (SHSNC) was evaluated for preliminary antibacterial applications. [Copyright &y& Elsevier]

Abstract: Conversion of biomass into electricity is possible using microbial fuel cells (MFCs). The present paper deals with the studies of a two-chambered salt bridge MFC using Enterobacter cloacae IIT-BT 08 in MYG medium. The effect of different electron mediators, concentration of the mediator, ionic strength (salt concentration) of the medium and the surface area of the salt-bridge in contact with the anode and cathode chambers on the power generation in MFCs are reported. In the case of methyl viologen (MV) (0.1mM) as the electron mediator, the voltage generation was 0.4V but no current was detected. Different concentrations of methylene blue (MB) were also studied as the mediator. A maximum voltage of 0.37V was seen at 0.05mM MB, whereas a maximum current and power of and , respectively, were observed in the case of 0.03mM MB with a voltage of 0.34V. The corresponding power density and current density of and , respectively, were obtained. When the surface area of the salt bridge in contact with the anode and cathode chambers was increased, a proportionate improvement in the power output from 19.2 to was detected. The maximum power density and current density of and , respectively, which are found to be very promising for a salt bridge MFC were observed. [Copyright &y& Elsevier]

Abstract: Polyampholytic hydrogels are crosslinked networks composed of positively and negatively charged repeat units that show entirely different properties from their originate polyelectrolyte polymers. Here we report a series of stimuli-responsive polyampholytic hydrogels designed with poly(N-isopropylacrylamide-co-sodium acrylate)/poly(ethyleneimine) [poly(NIPAM-co-SA)/PEI] through the interpenetrating network method. The polyampholytic IPN hydrogel containing 0.5g PEI showed a higher swelling capacity than the remaining PEI-formulated hydrogels. These gels demonstrated a relatively higher swellability at pH 5 or 6. The interaction of various surfactants and polymer solutions was evaluated at different concentrations. Both the non-ionic (Tween 80) and anionic (sodium dodecyl sulfate, SDS) surfactants promoted their swelling properties, while the cationic (dodecylpyridinium chloride, DPC) surfactant drastically reduced the swelling nature of the polyampholytic semi-IPN hydrogels. Because of more physical attractions between the polyampholytic IPN gels and DPC, it showed a greater thermal stability. The surfactant interactions were eventually studied using scanning electron microscopy. Further, the effect of different salts on the swelling properties of the polyampholytic IPN hydrogels has been demonstrated in detail. [Copyright &y& Elsevier]

Abstract: Hydrogel networks based on N-isopropylacrylamide (NIPAM) and sodium acrylate (SA) were prepared by redox-polymerization in the presence of N,N′-methylenebisacrylamide (MBA). Highly stable and uniformly distributed silver nanoparticles have been prepared using these hydrogel networks as a carrier via in situ reduction of silver nitrate in the presence of sodium borohydride as a reducing agent. It has been demonstrated that the hydrogel hybrid with different sizes of silver nanoparticles can be effectively employed as antibacterial material. [Copyright &y& Elsevier]

Abstract: Semi-interpenetrating polymer network (IPN) hydrogels composed of starch and random copolymer of poly(acrylamide-co-sodium methacrylate) [poly(AAm-co-NMA)] were prepared by polymerizing an aqueous solution of acrylamide (AAm), sodium methacrylate (NMA) using ammonium persulphate (APS)/N,N,N 1,N 1-tetramethylethylenediamine (TMEDA) as redox initiating system in presence of a crosslinker and starch solution. IR spectroscopy was used to identify the presence of different repeating units in the IPN networks. The swelling and diffusion characteristics, such as initial swelling rate (r i), swelling rate constant (k s), equilibrium swelling ratio (S eq), diffusion constant (n) and diffusion coefficients (D) were evaluated for different semi-IPN hydrogels prepared under various formulations. For better understanding of network structure formation of these semi-IPNs, three different crosslinkers namely, N,N-methylenebisacrylamide (MBA), 1,4-butanediol diacrylate (BDDA) and diallyl phthalate (DP) were employed. Further, the swelling pattern of semi-IPN hydrogels was studied in different physiological, pH and ionic/salt solutions and showed great responsiveness due to their ionic character. The morphological features of these IPNs were observed using scanning electron microscopy (SEM). [Copyright &y& Elsevier]

Pseudomonas aeruginosa PP4, Pseudomonas sp. PPD and Acinetobacter lwoffii ISP4 capable of utilizing phthalate isomers were isolated from the soil using enrichment culture technique. The strain ISP4 metabolizes isophthalate, while PPD and PP4 utilizes all three phthalate isomers ( ortho-, iso- and tere-) as the sole carbon source. ISP4 utilizes isophthalate (0.1%) more rapidly (doubling time, 0.9 h) compared to PPD (4.64 h), PP4 (7.91 h) and other reported strains so far. The metabolic pathways in these isolates were initiated by dihydroxylation of phthalate isomers. Phthalate is hydroxylated to 3,4-dihydro-3,4-dihydroxyphthalate and 4,5-dihydro-4,5-dihydroxyphthalate in strains PP4 and PPD, respectively; while terephthalate is hydroxylated to 2-hydro-1,2-dihydroxyterephthalate. All three strains hydroxylate isophthalate to 4-hydro-3,4-dihydroxyisophthalate. The generated dihydroxyphthalates were subsequently metabolized to 3,4-dihydroxybenzoate (3,4-DHB) which was further metabolized by ortho ring-cleavage pathway. PP4 and PPD cells grown on phthalate, isophthalate or terephthalate showed respiration on respective phthalate isomer and the activity of corresponding ring-hydroxylating dioxygenase, suggesting the carbon source specific induction of three different ring-hydroxylating dioxygenases. We report, for the first time, the activity of isophthalate dioxygenase and its reductase component in the cell-free extracts. The enzyme showed maximum activity with reduced nicotinamide adenine dinucleotide (NADH) in the pH range 8–8.5. Cells grown on glucose failed to respire on phthalate isomers and 3,4-DHB and showed significantly low activities of the enzymes suggesting that the enzymes are inducible. [ABSTRACT FROM AUTHOR]

Composite propellants are considered as major sources of chemical energy for rocket propellants. In the preparation of composite propellant energetic formulations, the propellant binder plays a vital role. Various energetic polymeric binders were developed during last five decades to satisfy safety, high energy and processing conditions. In this review, we discuss the various synthetic routes for of preparation of high energetic polymeric binders, including glycidyl azide polymers (GAP)s, GAP co-polymers, oxetane polymers, oxirane polymers, azido polyesters, N, N′-bonded epoxy binders, aliphatic vinyl azide polymers and poly(allyl azide) (PAAz). [ABSTRACT FROM AUTHOR]

Chemically crosslinked poly(acrylamide-co-maleic acid) [poly(AAm-co-MA)] hydrogels were prepared by simultaneous free radical copolymerization of acrylamide (AAm) with maleic acid (MA) in presence of di or tri functional crosslinking agents using ammonium persulfate-N,N,N',N'-tetramethylethylenediamine (APS-TMEDA) redox-initiating system. The poly(AAm-co-MA) hydrogels formation was confirmed by IR studies. The influence of crosslinkers such as N,N'-methylene-bis-acrylamide (MBA) and 2,4,6-triallyloxy-1,3,5-triazine (TATA) on swelling/de-swelling characteristics were studied in detail for poly(AAm-co-MA) hydrogels containing different amounts of maleic acid. The present investigation also deals with the influence of concentration of crosslinker and initiator on the swelling behavior of poly(AAM-co-MA) hydrogels. The effect of various salts on swelling capacity was studied. In addition, the effect of simulated biological fluids and pH solutions on the swelling of hydrogels was also studied in detail. [ABSTRACT FROM AUTHOR]

The present study reports the preparation of glycidyl azide polymer with enhanced azide content. This process involves the cationic ring-opening polymerization of epichlorohydrin (ECH) using borontrifluoride etherate (BF 3 -etherate) and 2,2-bis(bromomethyl)1,3-propane diol (BMPD) as initiator and co-initiators, respectively, followed by subsequent azidation of the product. For both the products, poly(epichlorohydrin)s (PECHs) and glycidyl azide polymers (GAPs) the substituted 1,3-propane diol units were characterized by spectroscopic as well as thermal analysis. Vapor pressure osmometer studies indicated that as the diol concentration increased in the polymerization the formed PECH molecular weight decreased. The spectral analysis indicates the presence of corresponding diol units in their polymeric chains. The differential scanning calorimetry and elemental analysis of the GAPs developed in this investigation indicated the presence of higher azide content in the polymer. [ABSTRACT FROM AUTHOR]

The present investigation describes the synthesis and characterization of poly(glycidyl azide-co-tetrahydrofuran) poly(GA-THF) or GAP-THF copolymers which are recognized as high-energy binders/plasticizers in explosive systems. GAP-THF copolymers were synthesized by copolymerization of epichlorohydrin (ECH) with tetrahydrofuran (THF) in presence of borontrifluoride etherate (BF 3 -etherate) and ethylene glycol (EG) as catalyst and co-catalyst, respectively; and subsequent azidation of the product with sodium azide in dimethylformamide at 120°C. The GAP-THF copolymers and their precursors PECH-THF copolymers were well characterized by UV, IR, 1 H-NMR, 13 C-NMR spectroscopy. Molecular weights of these copolymers were determined using VPO (Vapor pressure osmometer) and GPC (Gel permeation chromatography) techniques. The synthesized GAP-THF copolymer followed a thermal decomposition behavior in its DSC and TGA analyses similar to that of pure GAP. However, the copolymer GAP-THF has shown a very low glass transition temperature (Tg) of - 64°C. [ABSTRACT FROM AUTHOR]

Hydrogels based on acrylamide (AAM) and potassium methacrylate (KMA) were synthesized by simultaneous free radical polymerization in aqueous solution using the redox initiator ammonium persulfate (APS) and N,N,N′N′-tetramethylethylenediamine (TMEDA) at room temperature. Eight different compositions of KMA hydrogels were prepared at a fixed concentration of N,N′,-methylenebisacrylamide (MBA) or diallyl phthalate (DP) as crosslinking agents. For all the AAM-KMA hydrogels, the percentage of swelling, swelling kinetics, and diffusion characteristics were investigated. It was found that higher swelling percentage values were obtained for hydrogels crosslinked with DP than for the conventional crosslinker MBA. The de-swelling characteristics of hydrogels were also studied in detail. The power law relationship of hydrogels was evaluated in saline solutions. Hydrogels formation was confirmed by IR spectroscopy. The thermal characteristics of these hydrogels were studied by using differential scanning calorimeter (DSC) and thermogravimetric analyzer (TGA) and revealed that MBA crosslinked AAM-KMA hydrogels show higher glass transition temperature (Tg) as well as higher decomposition temperatures (Td) than DP crosslinked AAM-KMA hydrogels. It is further confirmed from the studies that the DP crosslinked hydrogels have good swelling as well as de-swelling and salinity characteristics. [ABSTRACT FROM AUTHOR]

A series of interpenetrating polymer networks (IPN) based on poly(vinyl alcohol) and poly(acrylamide-co-potassium methacrylate) were synthesized. The synthesis was effected by a semi-IPN method polymerizing an aqueous solution of acrylamide and potassium methacrylate using the APS/TMEDA initiating system with a cross-linker, in the presence of poly(vinyl alcohol). Four different cross-linkers were employed in the preparation of IPNs. The swelling behaviour of the IPNs was monitored as a function of acrylamide and potassium methacrylate ratios. The IPNs were synthesized by varying the cross-linker concentration and the experimental results showed that the cross-linker concentration is of great influence on the swelling behaviour. The network formation of IPNs cross-linked with various cross-linkers at two different concentrations was studied in detail by scanning electron microscopy (SEM). The IPNs being ionic, swelling is affected by the ionic strength as well as by the pH of the medium. Further the effect of simulated biological fluids on the swelling behaviour of PVA/poly(AAm-co-KMA) IPNs was also investigated. [ABSTRACT FROM AUTHOR]

Cross-linked co-polymers containing glycidyl azide polymer (GAP) and hydroxyl-terminated poly(butadiene) (HTPB) segments have been obtained by chemical reactions. The reactions involves two steps. In the first step the GAP macroinitiator (GAPMI) is synthesized by the condensation reaction of GAP-diol with 4,4'-azobis(4-cyanopentanoic acid) (ACPA) in the presence of N-methyl-2-chloropyridinium iodide (MCPI). The GAPMI obtained is used for the cross-linking or grafting reactions with HTPB at an elevated temperature in the second step. The cross-linked co-polymers are isolated from the crude reaction mixture by fractional precipitation technique using chloroform as solvent and methanol as non-solvent. The co-polymers have been well characterized by using IR, 1H-NMR and 13C-NMR spectral analysis, and the molecular weights of the co-polymers have been determined by gel permeation-chromatography (GPC) and vapour pressure osmometry (VPO). The co-polymer exhibited two glass transition temperatures for HTPB-GAP co-polymer, at –74.03°C and –35.84°C. During the thermal analysis, the cross-linked co-polymers exhibited two exothermic peaks and one endothermic peak, indicating the presence of HTPB and GAP polymeric chain segments in the co-polymers. Further, the TGA studies revealed a four step-weight loss, suggesting the decomposition of the co-polymer is similar to that of their homo-polymers. [ABSTRACT FROM AUTHOR]

Abstract: Superabsorbent copolymers (SAPs) based on acrylamide (AAM) and sodium methacrylate (NMA) were prepared by simultaneous free radical polymerization in aqueous solution using ammonium persulfate (APS) and N,N,N′,N′-tetramethylethylenediamine (TMEDA) as initiating systems at room temperature. Eight different copolymers were prepared by varying NMA with a fixed concentration of acrylamide and 1,4-butanediol diacrylate (BDDA) or ethyleneglycol dimethacrylate (EGDMA) as crosslinkers. The acrylamide–sodium methacrylate (AAM–NMA) SAP formation was confirmed by IR spectroscopy. The percentage of swelling, swelling and diffusion kinetic parameters (i.e., initial swelling network constant, swelling rate constant, maximum swelling equilibrium, network structure constant and type of diffusion, etc.) were investigated for all the SAPs at 25°C. The swelling behaviour was also studied at different temperatures ranging from 10 to 50°C. The effect of different reaction parameters, such as, crosslinker, initiator and activator concentrations on the swelling capacity was investigated. The effect of variation of crosslinker concentration on the copolymer network structure was studied by SEM analysis. Further the saline sensitivity of the copolymers was investigated at different saline concentrations. The effect of pH and de-swelling behaviour for AAM–NMA SAPs prepared at optimum reaction conditions was studied. [Copyright &y& Elsevier]

The present work describes a convenient process for the preparation of low molecular weight hydroxyl-terminated glycidyl azide polymers. The facile route involves the formation of glycidyl azide polymer in a single step. The polymerization of epichlorohydrin was carried out in dipolar aprotic solvent N,N 1 -dimethylformamide (DMF) medium using diols as initiators in the presence of sodium azide. Various low molecular weight diols such as ethylene glycol (EG), propylene glycol (PG), diethylene glycol (DEG), 2-methylpentane-2,4-diol (MPD), and resorcinol (RS) are employed as initiators in the present investigation. The effect of initiating diols on the polymer formation was confirmed by gel permeation chromatography (GPC) and vapor pressure osmometry (VPO). The GPC analysis indicates that the glycidyl azide polymers (GAPs) contain different-sized oligomers, due, to the multimodal molecular weight distribution. The GAPs obtained in all the polymerizations by using different diols have a maximum of five to seven glycidyl azide repeating units. Further, the effect of diol on the GAP decomposition was investigated, and it was found that the GAPs obtained by using different diol units have a thermal decomposition pattern similar to that of glycidyl azide polymer. Since the glycidyl azide polymers have low molecular weights, their glass transition temperatures, are lower, betweens - 70° and - 72°C, due to variation in the structure of the polymers. Structural analysis of the GAPs using spectral methods revealed that the initiating diol units are present in the polyether backbone of GAPs. Nitrogen content and solubility tests were also performed. [ABSTRACT FROM AUTHOR]

The study was carried out to learn about the nature of gene action and combining ability in rice hybrids for grain yield and its component traits. For this, eight lines were crossed with four testers in an L x T mating design. The analysis of variance revealed significant variance for all the characters studied among the parents and hybrids. GCA variances were higher than SCA variances for most of the characters, indicating the predominance of additive gene action, while SCA variances were higher than GCA variances for number of productive tillers per plant, pollen fertility, hulling, milling, head rice recovery and grain yield per plant, indicating the predominance of non-additive gene action. The testers JMS 13A (3.91) and CMS 59A (2.46), as well as the lines MTU 1153 (9.52), RNR 28355 (3.26) and RNR 26085 (3.09), were the best combiners for grain yield and important yield components due to positive GCA effects. Based on SCA effects and corresponding mean performance for grain yield and its component traits, the hybrids CMS 59Ax RNR 26015, CMS 23A x JGL 25960, CMS 64Ax RNR 26015 and JMS 13Ax MTU 1153 were identified as the best specific combiners. These hybrids could be tested in multi-environment trials for commercial use. [ABSTRACT FROM AUTHOR]

Screening of 12 marine sediment samples near pudimadaka Coast of the Bay of Bengal at different depths resulted in the isolation of 98 isolates of actinomycetes. On the basis of sporophore morphology and structure of the spore chain, 83 isolates were assigned to the genus Streptomyces, 7 isolates to the genus Micromonospora, 5 to the genus Nocardia and 3 to the genus Streptoverticilium. Among 98 isolates, 29 isolates showed antibacterial activity and 16 isolates showed antifungal activity. Seven isolates showed promising activities against the bacteria and three isolates showed highest activities against the pathogenic fungi. [ABSTRACT FROM AUTHOR]

Abstract Grain size has significant effects on the electromechanical response of piezoceramics. Since the sintering temperature and holding duration affect the grain size and correspondingly their effective piezoelectric response, these issues should be appropriately addressed in order to properly design smart and intelligent systems. In this paper, PMN-PT piezoceramics with different grain sizes are synthesized by using conventional solid state processing and two-stage sintering method. Grain size effects on the hysteresis, fatigue and creep response are analyzed. Dielectric, ferroelectric and piezoelectric material properties of PMN-PT ceramics are investigated. The piezoelectric coefficient and remnant polarization exhibit diverse grain size effects depending on the sintering temperature and holding duration. The relative dielectric permittivity, piezoelectric coupling constant and dielectric constant show maximum values of 4104.2, 559 pC/N 562.291 pC/N and 0.705 for the microstructure with average grain size of 3.8 μm. The myriad effects of grain size on piezoelectric response are reported in details. [ABSTRACT FROM AUTHOR]

A total of 21 rice genotypes (resistant to gall midge biotype 3 and BPH were evaluated for their variability and genetic divergence. The highest genotypic and phenotypic coefficient of variation, heritability and genetic advance % of mean corresponded to grains per panicle, seed yield, 1000 grain weight and plant height and direct selection for these traits would be useful for yield improvement in rice. The D² values were significant among the 21 genotypes, which were grouped into 6 clusters. Most of the genotypes with same pedigree either male or female parent involved cross combination came under the same cluster and few genotypes in different cluster and genotypes of quite different pedigree may all into the same cluster. For getting desirable transgressive segregants for the development of early duration (Genotypes from the clusters II and Cluster VI) and medium duration (from the clusters I and IV), coarse and medium slender high yielding gall midge and BPH resistant varieties genotypes could be utilized in the hybridization programme. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, we report the preparation of semi interpenetrating hydrogel networks (SIHNs) based on cross-linked poly (acrylamide) prepared through an optimized rapid redox-solution polymerization with N,N′-methylenebisacrylamide (MBA) in presence of three different carbohydrate polymers, namely gum acacia (GA), carboxymethylcellulose (CMC) and starch (SR). Highly stable and uniformly distributed silver nanoparticles have been obtained with hydrogel networks as nanoreactors via in situ reduction of silver nitrate (AgNO3) using sodium borohydride (NaBH4) as reducing agent. The formation of silver nanoparticles has been confirmed with ultraviolet visible (UV–vis) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) analyses. Thermogravimetric analysis (TGA) provides the amounts of silver nanoparticles exist in the hydrogel networks. Transmission electron microscopy (TEM) results demonstrate that acacia employed hydrogels have regulated the silver nanoparticles size to 2–5nm where as CMC and starch composed hydrogel networks result in a heterogeneous size from 2 to 20nm. The preliminary antibacterial activity performed to these hydrogel–silver nanocomposites. [Copyright &y& Elsevier]

The incorporation of metal nanoparticles into polymers has resulted in the origination of a new class of materials that have found fascinating interest in biomedical, catalytic, optical and electronic as well as quantum-size domain applications. This review article describes different strategies that have been adopted for the synthesis of metal nanocomposite materials with polymers and gel macromolecules (hydrogels and nanogels). [ABSTRACT FROM AUTHOR]

A series of novel crosslinked copolymers based on the monomers acrylamide (AM), calcium acrylate (CA), and sodium methacrylate (SMA) were prepared by aqueous solution polymerization using ammonium persulfate (APS) as initiator and N, N-methylene-bis-acrylamide (MBA) as crosslinking agent. The synthetic variables monomer concentration, crosslinker concentration, initiator concentration were also studied. The experimental results of SAPs show good absorbency in both water and NaCl solutions. The copolymers were characterized by IR spectroscopy. The water retention of SAPs was studied in an oven at 60 and 100°C. [ABSTRACT FROM AUTHOR]

The Al2O3-SiC reinforced Al7075 Metal Matrix Composite (MMCs) is fabricated through liquid metallurgical technique. Ceramic particulates were amalgamated into the aluminium alloy to achieve improved mechanical properties and wear resistance. Al-7075/Al2O3/SiC hybrid MMCs were produced by reinforcing 2%, 3%, 4% and 5% of Al2O3 and 3%, 5% and 7% of SiC particles. Microstructural analysis was carried out to evaluate the uniform dispersal of reinforcing particulates within the base matrix. The output results indicate that the mechanical properties of the hybrid MMCs are enhanced by increase the wt. % of ceramic particulates. Tensile fractography results show the internal fracture structure of the tensile test specimens in which the particulates fracture and pullouts were observed. The wear characteristics of developed composites are studied using the pin-on-disc apparatus. The high wear resistance is observed at 5% Al2O3 + 7% SiC reinforced MMCs. [ABSTRACT FROM AUTHOR]

Centella asiatica is an endemic herbaceous plant with great medicinal value. Medicinal properties of the plant has led to it's over exploitation coupled with inadequate cultivation and unsatisfactory attempts for its replacement, the wild stock of this species has been markedly exhausted and now it is listed as threatened species. Hence, there is an urgent necessitate to safeguard this precious germplasm. Plant tissue culture has proved to be helpful in conserving threatened plant species. In this direction, in the present study, an efficient protocol was developed for callus induction and plantlet regeneration from nodal explants of Centella asiatica. Well-organized plant regeneration was achieved on MS medium containing different concentrations and combinations of growth regulators. MS medium supplemented with 4 mg/ l and NAA in combination with 2 mg/l 2, 4-D proved effective for callus induction, with this combination we achieved a frequency of 92% and BAP 1.5 mg/l and KN 1.5 mg/l was effective for regeneration response. [ABSTRACT FROM AUTHOR]

Abstract: Ligand-free, palladium-supported, poly(N-isopropylacrylamide-co-potassium methacrylate) [poly(NIPA-co-PMA)] hydrogel nanocomposite with different comonomer ratios were synthesized. The developed hydrogel–palladium composites were characterized by SEM, TEM, UV–vis DRS and XRD. The catalytic performance of these hydrogel–palladium nanocomposites was examined for Suzuki–Miyaura cross-coupling reaction of aryl halides with arylboronic acids in an aqueous medium. The hydrogel with comonomer ratio of 8.8:1.6mmol of NIPA:PMA exhibited optimum catalytic activity, which can be effectively reused 5–6 times without loss of catalytic activity. [Copyright &y& Elsevier]

The semi-interpenetrating polymer network (IPN) hydrogels composed of poly(vinyl alcohol) (PVA) and random copolymers of poly(acrylamide-co-sodium methacrylate), poly(AAm-co-NMA); poly(acrylamide-co-potassium methacrylate), poly(AAm-co-KMA); poly(acrylamide-co-maleic acid), poly(AAm-co-MA) were prepared by conventional co-polymerization employing ammonium persulphate (APS)/N,N,N1,N1-tetraethylmethylenediamine (TMEDA) as redox initiating system in presence of N,N1-methylenebisacrylamide (MBA) as a crosslinker. The swelling behavior of these semi-IPN hydrogels were compared in detail in various swelling media, including different pH, salt, and biological fluids. [ABSTRACT FROM AUTHOR]