Bio: Parul Jain is an academic researcher from Indian Institutes of Technology. The author has contributed to research in topics: Perovskite (structure) & Sephadex. The author has an hindex of 3, co-authored 5 publications receiving 86 citations.
TL;DR: In this article, perovskite related dielectric oxides have been synthesized by the NaCl-KCl molten salt (flux) method at low temperatures of 900°C for 3 or 6 hours.
Abstract: Perovskite related dielectric oxides of the formula Ba(Zn1/3Nb2/3)O3, Ba(Mg1/3Nb2/3)O3 and Ba(Zn1/3Ta2/3)O3 have been synthesized by the NaCl–KCl molten salt (flux) method at low temperatures of 900°C for 3 or 6 h. Sintering at 1000°C retained the cubic structure. Sintering at 1300°C generated minor amount (∼10%) of Ba5Nb4O15 in addition to the main cubic phase for the niobium compounds. The tantalum compounds, on the other hand, decomposed to Ba0.5TaO3, retaining a minor amount of the original cubic phase. Scanning electron micrographs show large grain size (upto 10 μm) in some of the samples obtained by the molten salt method.
TL;DR: A quick and efficient two-step assay for monitoring and screening lipase activity that uses a microtitre plate is described.
Abstract: A quick and efficient two-step assay for monitoring and screening lipase activity that uses a microtitre plate is described.
TL;DR: In this article, the spontaneous ferroelectric polarization (PS) and the magnetization M with only 2% Sr doping was observed in a magnetic multiferroic material CaMn7O12, where PS dramatically becomes more than double the PS in the un-doped material and concomitantly M is reduced to less than half of its value therein.
Abstract: CaMn7O12 is a magnetic multiferroic material, in which large ferroelectric polarization has reportedly been induced by magnetic ordering. In this work, we observe remarkable changes in the spontaneous ferroelectric polarization PS as well as the magnetization M with only 2% Sr doping. In Ca0.98Sr0.02Mn7O12, PS dramatically becomes more than double the PS in the un-doped material and concomitantly M is reduced to less than half of its value therein. Increase of PS together with the decrease of M points out clearly the coupling of PS and M in CaMn7O12. We stress here that as Ca and Sr are isovalent, no charge carriers (electrons and holes) are added in the system due to Sr-doping. X-ray diffraction shows that all our Sr-doped materials Ca1-xSrxMn7O12 (x = 0.01, 0.02, 0.05, 0.10) are free from secondary phases. From our work, it becomes clear why SrMn7O12 exhibits no or weak ferroelectricity.
TL;DR: The enzyme, purified by ammonium sulphate precipitation and Sephadex G-75 gel filtration, showed a molecular weight of 25,000 and activity between pH 6.0 and 9.5, with an optimum of 9.0 in Tris-maleate buffer.
Abstract: Conditions are described for the production of extracellular elastase by Bacillus subtilis. The yield of enzyme was maximum in shake–cultures grown in Syncase medium at 37 °C and was stable in culture supernatants. The enzyme, purified by ammonium sulphate precipitation and Sephadex G-75 gel filtration, showed a molecular weight of 25 000 and activity between pH 6.0 and 9.5, with an optimum of 9.0 in Tris–maleate buffer. Elastinolytic activity was maximum in glycine–NaOH buffer and minimum in phosphate buffer. Enzyme activity was adversely affected by temperature ≥ 40 °C.
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TL;DR: A context-aware reasoning framework that adapts to the needs and preferences of inhabitants continuously to provide contextually relevant recommendations to the group of users in a smart home environment is introduced.
Abstract: This paper introduces a context-aware reasoning framework that adapts to the needs and preferences of inhabitants continuously to provide contextually relevant recommendations to the group of users in a smart home environment. User’s activity and mobility plays a crucial role in defining various contexts in and around the home. The observation data acquired from disparate sensors, called user’s context, is interpreted semantically to implicitly disambiguate the users that are being recommended to. The recommendations are provided based on the relationship that exist among multiple users and the decision is made as per the preference or priority. The proposed approach makes extensive use of multimedia ontology in the life cycle of situation recognition to explicitly model and represent user’s context in smart home. Further, dynamic reasoning is exploited to facilitate context-aware situation tracking and intelligently recommending appropriate actions which suit the situation. We illustrate use of the proposed framework for Smart Home use-case.
TL;DR: The scanning electron microscopic (SEM) studies showed that morphology of CLEA changed upon inactivation by reuses and the lipase activity and α-amylase activity in CLEA were completely retained upto three cycles of use.
Abstract: A novel cross-linked enzyme aggregates (CLEA) concept called combi-CLEA has been described. It is based upon the fact that CLEA can be made from heterogeneous populations of proteins/enzymes. Porcine pancreatic acetone powder crude extract was used for preparing CLEA in such a way that lipase, α-amylase, phospholipase A 2 activities were retained upto 100%. The lipase present in the CLEA showed greater thermal stability at 50 °C as compared to free enzyme. For lipase and phospholipase A 2 , V max / K m showed no significant change upon combi-CLEA formation but decreased significantly for α-amylase activity from 190 to 114 min −1 . The lipase activity and α-amylase activity in CLEA were completely retained upto three cycles of use. The scanning electron microscopic (SEM) studies showed that morphology of CLEA changed upon inactivation by reuses.
TL;DR: Results suggest that the CWDEs NAGase and β-1,3-glucanase and sclerotia parasitism are key components of Trichoderma spp.
Abstract: Field outcomes of 10 Trichoderma spp isolates against white mold ( Sclerotinia sclerotiorum ) on common beans were matched to laboratory results, to identify the causes of variance related to biocontrol effectiveness Laboratory assays estimated sclerotia parasitism and production of the cell wall-degrading enzymes (CWDEs) lipase, NAGase, β-1,3-glucanase, β-glucosidase and protease Field trials were carried out in 2009 and 2010 under a randomized block design and sprinkling irrigation, where 2 × 10 12 spores mL −1 of each antagonist were applied to the plots at the early R5 stage The density of S sclerotiorum apothecia m −2 and disease severity were assessed, respectively at R7 and R8 stages, with yield and its components also estimated for each year Field results were analyzed jointly by the Tukey–Kramer multiple comparison test, and all variables from both field and laboratory experiments were subjected to principal component analysis (PCA) In both years, isolates TR696 and TR356 of Trichoderma asperellum were effective in reducing apothecia density and disease severity Biocontrol increased the number of pods per plant and yields up to 40% when compared to controls, even under higher disease pressure in 2010 PCA demonstrated in 2009 and 2010 that apothecia density, disease severity, NAGase, β-1,3-glucanase and number of pods were the main sources of the first component of variance Such results suggest that the CWDEs NAGase and β-1,3-glucanase and sclerotia parasitism are key components of Trichoderma spp action in biocontrol of S sclerotiorum in the field, and may be used as markers to hasten the selection of new, promising isolates
TL;DR: In contrast to the effects of ultrasonic irradiation on other enzymes, for the lipases focused upon in this study, an enhancement of biocatalytic activity is reported, thought to originate from morphological changes on the macro and molecular levels.
Abstract: Ultrasound has been used to accelerate the rates of numerous chemical reactions, however its effects on enzymatic reactions have been less extensively studied. While known to result in the acceleration of enzyme-catalysed reactions, ultrasonication has also been shown to induce enzyme inactivation. In this study we investigated the effects of ultrasonic pretreatment on lipases in both aqueous and non-aqueous media. Our results show that the ultrasonic pre-irradiation of lipases (from Burkholderia cepacia and Pseudomonas fluorescens) in aqueous buffer and organic solvents enhanced enzymic activities. In addition, we report the enhancement of hydrolytic (esterase) and transesterification activities. On using pre-irradiated enzyme, we found that the conversion rate for the transesterification of ethyl butyrate to butyl butyrate, increased from 66% to 82%. Similarly, a 79% conversion of Jatropha oil to biodiesel was observed upon employing pre-irradiated enzyme, in contrast to a 34% conversion with untreated enzyme. CD spectra showed that while the enzyme's secondary structure remained largely unaffected, the microenvironments of aromatic amino acids were altered, with perturbation of the tertiary structure having also occurred. SEM analysis demonstrated significant morphological changes in the enzyme preparation as a result of ultrasonication. In contrast to the effects of ultrasonic irradiation on other enzymes, for the lipases focused upon in this study, we report an enhancement of biocatalytic activity, which is thought to originate from morphological changes on the macro and molecular levels.
TL;DR: Successful immobilization of enzymes on nanosized carriers could pave the way for reduced reactor volumes required for biotransformations, as well as having a use in the construction of miniaturized biosensensor devices.
Abstract: Immobilization of biologically active proteins on nanosized surfaces is a key process in bionanofabrication. Carbon nanotubes with their high surface areas, as well as useful electronic, thermal and mechanical properties, constitute important building blocks in the fabrication of novel functional materials. Lipases from Candida rugosa (CRL) were found to be adsorbed on the multiwalled carbon nanotubes with very high retention of their biological activity (97%). The immobilized biocatalyst showed 2.2- and 14-fold increases in the initial rates of transesterification activity in nearly anhydrous hexane and water immiscible ionic liquid [Bmim] [PF6] respectively, as compared to the lyophilized powdered enzyme. It is presumed that the interaction with the hydrophobic surface of the nanotubes resulted in conformational changes leading to the 'open lid' structure of CRL. The immobilized enzyme was found to give 64% conversion over 24 h (as opposed to 14% with free enzyme) in the formation of butylbutyrate in nearly anhydrous hexane. Similarly, with ionic liquid [Bmim] [PF6], the immobilized enzyme allowed 71% conversion as compared to 16% with the free enzyme. The immobilized lipase also showed high enantioselectivity as determined by kinetic resolution of (±) 1-phenylethanol in [Bmim] [PF6]. While free CRL gave only 5% conversion after 36 h, the immobilized enzyme resulted in 37% conversion with > 99% enantiomeric excess. TEM studies on the immobilized biocatalyst showed that the enzyme is attached to the multiwalled nanotubes. Successful immobilization of enzymes on nanosized carriers could pave the way for reduced reactor volumes required for biotransformations, as well as having a use in the construction of miniaturized biosensensor devices.
TL;DR: These various enzyme formulates were evaluated for the kinetic resolution of (+/-)-1-phenylethanol in ionic liquid by transesterification with vinyl acetate and the acetone-rinsed enzyme preparation (AREP), CLEA, CLEA and PCMC performed equally well.
Abstract: Lipases from two different sources Candida rugosa (CRL) and Burkholderia cepacia (BCL) were formulated as enzyme precipitated and rinsed with organic solvents, organic solvent rinsed enzyme preparation, cross-linked enzyme aggregates (CLEAs) and protein coated micro-crystals (PCMCs). These various enzyme formulates were evaluated for the kinetic resolution of (±)-1-phenylethanol in ionic liquid [Bmim][PF 6 ] by transesterification with vinyl acetate. Of all the enzyme forms evaluated EPRP and PCMC in the case of CRL showed the best results with 26 % ( E value = 153) and 53% ( E value = 79) conversion, respectively, at 35 °C in 24 h. Carrying out this conversion with PCMC at lower temperature of 25 °C further improved the E value to 453 (with 44% conversion in 12 h). For BCL the acetone-rinsed enzyme preparation (AREP), CLEA and PCMC performed equally well with % conversion of 50 and 99 ee p (%) ( E value >1000) in just 2 h, whereas, the free lipase gave only 8% conversion.