Showing papers by "Vignan University published in 2017"

N-, O-, and S-Tridoped Carbon-Encapsulated Co9S8 Nanomaterials: Efficient Bifunctional Electrocatalysts for Overall Water Splitting

Abstract: The development of highly active and stable earth-abundant catalysts to reduce or eliminate the reliance on noble-metal based ones in green and sustainable (electro)chemical processes is nowadays of great interest. Here, N-, O-, and S-tridoped carbon-encapsulated Co9S8 (Co9S8@NOSC) nanomaterials are synthesized via simple pyrolysis of S- and Co(II)-containing polypyrrole solid precursors, and the materials are proven to serve as noble metal-free bifunctional electrocatalysts for water splitting in alkaline medium. The nanomaterials exhibit remarkable catalytic performances for oxygen evolution reaction in basic electrolyte, with small overpotentials, high anodic current densities, low Tafel slopes as well as very high (nearly 100%) Faradic efficiencies. Moreover, the materials are found to efficiently electrocatalyze hydrogen evolution reaction in acidic as well as basic solutions, showing high activity in both cases and maintaining good stability in alkaline medium. A two-electrode electrolyzer assembled using the material synthesized at 900 °C (Co9S8@NOSC-900) as an electrocatalyst at both electrodes gives current densities of 10 and 20 mA cm−2 at potentials of 1.60 and 1.74 V, respectively. The excellent electrocatalytic activity exhibited by the materials is proposed to be mainly due to the synergistic effects between the Co9S8 nanoparticles cores and the heteroatom-doped carbon shells in the materials.

Ag@CoxP Core–Shell Heterogeneous Nanoparticles as Efficient Oxygen Evolution Reaction Catalysts

Abstract: We present a facile synthetic method that yields Ag@CoxP core–shell-type heterogeneous nanostructures with excellent oxygen evolution reaction (OER) activity. This nanocatalyst can deliver a current density of 10 mA/cm2 at a small overpotential of 310 mV and exhibits high catalytic stability. Additionally, the catalytic activity of Ag@CoxP is 8 times higher than that of the Co2P nanoparticles, owing primarily to the strong electronic interaction between the Ag core and the CoxP shell.

Hydrogen production by photocatalytic water-splitting on Pt-doped TiO2–ZnO under visible light

Abstract: Pt/TiO 2 –ZnO photocatalytic materials were prepared for the generation of hydrogen gas from water splitting. The photocatalysts were characterized by X-ray diffraction (XRD), UV-visible spectra (UV–Vis), scanning electron microscope (SEM) and transmission electron microscope (TEM). The absorption wavelength of TiO 2 was shifted to longer wavelength on Pt/TiO 2 –ZnO. A 400 W mercury arc lamp with a cutoff filter which filter out all the wavelengths under 400 nm as the visible light source. It reached up to the optimum value of 203 µmolh −1 g −1 on TiO 2 –ZnO (Ti/Zn = 10). A catalyst of 0.5 wt% Pt/TiO 2 –ZnO (Ti/Zn = 10) was used and a best hydrogen production rate through water splitting was reaching to 2150 µmolh −1 g −1 . The 0.1 wt% Pt/TiO 2 –ZnO showed a satisfying long-term stability, and 88% and 77% of initial hydrogen productivity still remained after 7 days and 14 days, respectively.

An Update on Clinical Burden, Diagnostic Tools, and Therapeutic Options of Staphylococcus aureus:

Abstract: Staphylococcus aureus is an important pathogen responsible for a variety of diseases ranging from mild skin and soft tissue infections, food poisoning to highly serious diseases such as osteomyelitis, endocarditis, and toxic shock syndrome. Proper diagnosis of pathogen and virulence factors is important for providing timely intervention in the therapy. Owing to the invasive nature of infections and the limited treatment options due to rampant spread of antibiotic-resistant strains, the trend for development of vaccines and antibody therapy is increasing at rapid rate than development of new antibiotics. In this article, we have discussed elaborately about the host-pathogen interactions, clinical burden due to S aureus infections, status of diagnostic tools, and treatment options in terms of prophylaxis and therapy.

Monitoring and assessment of heavy metal contamination in a constructed wetland in Shaoguan (Guangdong Province, China): bioaccumulation of Pb, Zn, Cu and Cd in aquatic and terrestrial components

Abstract: The objective of this study is to evaluate the current status of heavy metal concentrations in constructed wetland, Shaoguan (Guangdong, China). Sediments, three wetland plants (Typha latifolia, Phragmites australis, and Cyperus malaccensis), and six freshwater fish species [Carassius auratus (Goldfish), Cirrhinus molitorella (Mud carp), Ctenopharyngodon idellus (Grass carp), Cyprinus carpio (Wild common carp), Nicholsicypris normalis (Mandarin fish), Sarcocheilichthys kiangsiensis (Minnows)] in a constructed wetland in Shaoguan were collected and analyzed for their heavy metal compositions. Levels of Pb, Zn, Cu, and Cd in sediments exceeded approximately 532, 285, 11, and 66 times of the Dutch Intervention value. From the current study, the concentrations of Pb and Zn in three plants were generally high, especially in root tissues. For fish, concentrations of all studied metals in whole body of N. mormalis were the highest among all the fishes investigated (Pb 113.4 mg/kg, dw; Zn 183.1 mg/kg, dw; Cu 19.41 mg/kg, dw; 0.846 mg/kg, dw). Heavy metal accumulation in different ecological compartments was analyzed by principle component analysis (PCA), and there is one majority of grouped heavy metals concentration as similar in composition of ecological compartment, with the Cd concentration quite dissimilar. In relation to future prospect, phytoremediation technology for enhanced heavy metal accumulation by constructed wetland is still in early stage and needs more attention in gene manipulation area.

Morita-Baylis-Hillman (MBH) Reaction Derived Nitroallylic Alcohols, Acetates and Amines as Synthons in Organocatalysis and Heterocycle Synthesis.

Abstract: The Morita–Baylis–Hillman (MBH) reaction is one of the most useful and efficient protocols for constructing new carbon–carbon bonds between an activated olefin and electrophiles in the presence of a tertiary amine/phosphine. Herein, we present the use of MBH alcohols, which are obtained from the reaction of nitrostyrenes with aldehydes, as well as acetates and amines derived thereof in several organocatalytic transformations. Densely functionalised MBH adducts can also be used to synthesise substituted heteroaromatic compounds, such as furan, pyrrole, pyrazole and imidazole derivatives.

Integration of Demand and Supply Side Management strategies in Generation Expansion Planning

Abstract: Electric utilities across the globe concerned with environmental issues associated with conventional fossil fuel based plants are exploring more into the possibility of introducing Renewable Energy Sources (RES) type of plants into the system as an alternative. A realistic power system planning needs integration of both Demand Side Management (DSM) and Supply Side Management (SSM) that which involve simultaneous consideration of both quantitative and qualitative issues like plant mix, costs and reliability of power supply. In this paper, an attempt is made to study the economic and environmental influence of RES introduction into an existing peak deficit power system, in the state of Tamil Nadu (TN), India, using the Long-Range Energy Alternative Planning system (LEAP) an energy-economic model, integrating both DSM and SSM strategies. The Generation Expansion Planning (GEP) study is carried out for TN power system for the period of thirty years from 2014 to 2043. The Base System Analyses (BSA) carried out was indicative of differential impact of RES levels and Reserve Margin on the system performance. Based on the BSA, an extended three dimensional sensitivity analysis was performed to get a comprehensive picture of the impact of variations in RES and Reserve Margin planned on system performance factors such as, Total Installed Capacity (TIC), Net Present Value (NPV) of investments, reliability of the system (ENS-Energy Not Served), one hundred year global warming potential (CO2E) and Flexibility Index (FI) for every DSM and SSM strategy planned. While TIC and NPV were more sensitive to changes in Reserve Margin (RM) than RES penetrations levels, the CO2E and FI were more sensitive to RES penetration levels. The ENS was sensitive to both RM and RES levels. The results also indicate that simultaneous implementation of DSM and SSM strategies could result in the reduction of as much as 10% in TIC, 18% in NPV, 23% in CO2E, 18% in ENS and 20% improvement in FI value.

Evaluation of Recombinant Multi-Epitope Outer Membrane Protein-Based Klebsiella pneumoniae Subunit Vaccine in Mouse Model.

Abstract: Safety and protective efficacy of recombinant multi-epitopic subunit vaccine (r-AK36) comprising immunodominant antigens from outer membrane proteins (Omp’s) of Klebsiella pneumoniae namely OmpA and OmpK36 was evaluated in mouse model. r-AK36 was highly immunogenic and the hyperimmune sera reacted strongly with native OmpA and OmpK36 proteins from different K. pneumoniae strains. Hyperimmune sera showed cross reactivity with Omp’s of other Gram negative organisms. Humoral responses showed a Th2- type polarized immune response with IgG1 being the predominant antibody isotype. Anti-r-AK36 antibodies showed antimicrobial effect during in vitro MIC testing with values in range of 25-50 µg/ml on different K. pneumoniae strains. The recombinant antigen elicited three-fold higher proliferation of splenocytes from immunized mice indicating possible T-cell clonal proliferation and differentiation into effector cells. Anti-r-AK36 antibodies also exhibited in vitro biofilm inhibition property. Subunit vaccine r-AK36 immunization promoted induction of anti-inflammatory cytokines in immunized mice. When r-AK36 immunized mice were challenged with 3xLD100 dose, ~80 % of mice survived beyond the observation period. Passive antibody administration to naive mice protected them (67 %) against the lethal challenge. Since the targeted OMPs are conserved among all K. pneumoniae serovars and due to the strong nature of immune responses, r-AK36 subunit vaccine could be a safe and cost effective candidate against klebsiellosis.

Recombinant pharmaceutical protein production in plants: unraveling the therapeutic potential of molecular pharming

Abstract: There is an increasing demand for the generation of recombinant pharmaceutical proteins for a wide array of therapeutic applications. In comparison to bacterial, yeast and animal cells, the production of recombinant proteins in plants with economic and therapeutic importance has only started recently. The most important prerequisite of any expression systems is that it should be simple and inexpensive. In this regard, plant-based expression has emerged an as accepted alternative to conventional expression platforms due to economic feasibility, rapid scalability, higher stability of recombinant proteins, safety due to lack of harmful substances (human, animal pathogens and pyrogens) and capability of producing proteins with desired secondary modifications. Heterologous expression using plants has played a pivotal role in the development of a myriad of recombinant proteins, including neutraceuticals and monoclonal antibodies being utilized in various therapeutic approaches. This paper presents an overview about the current status, various strategies and advantages of pharmaceutical protein production in plant expression systems. We also present a summary of expression of therapeutic monoclonal antibodies, vaccines, clinical trials and the regulatory aspects of plant-based expression. Furthermore, the challenges encountered in plant expression such as costs associated with existing purification strategies are discussed.

A Novel Imidazole-Core-Based Benzoxazine and Its Blends for High-Performance Applications

Abstract: In the present work, a novel imidazole-core-based bisphenol (IBP) was synthesized and characterized. The IBP and formaldehyde were reacted separately with aniline and N,N-dimethylaminopropylamine (DMAPA) under appropriate conditions to obtain benzoxazines, which were characterized for their molecular structure and thermal behavior using different analytical methods. Both types of benzoxazines, imidazole core–aniline-based benzoxazines (IBPA-Bz) and imidazole core–DMAPA-based benzoxazines (IBPD-Bz), possess better glass temperatures (Tg) and higher char yields than conventional benzoxazines (bisphenol-F-based benzoxazine (BPFb) and bisphenol-A-based benzoxazine (BPAb)). However, the curing temperature (Tp) of IBPD-Bz is lower than that of IBPA-Bz. The blending of IBPA-Bz with conventional benzoxazines (BPAb and BPFb) improved their thermal stability to an appreciable extent. Furthermore, the addition of bismaleimide cross-linkers (4,4′-diaminodiphenylsulfone- and 4,4′-diaminodiphenylmethane-based bismaleim...

A Novel Square Wave Generator Using Second-Generation Differential Current Conveyor

Abstract: By using two resistors and a single capacitor with second-generation differential current conveyor as an active element, a new square wave generator is proposed and implemented. The frequency of operation of the introduced model is varied with respect to the variation of remaining passive components. Maximum reduction in noise effects caused by parasitics generated during integrated circuit fabrication is achieved with the scheme of grounded capacitor. The mathematical model of the selected circuit is verified in both simulation and experimental mode and found having matched in all three aspects. The elevated advantages and merits of the given topology are compared and tabulated contrary to the existing standard models. Using Cadence virtuoso with gpdk 180 nm libraries, the circuit is verified with a supply rail voltage of ±2.5 V. Later, prototype is also tested with commercially available current feedback operational amplifiers of AD844AN.

Assignment of weightage to machining characteristics to improve overall performance of machining using GTMA and utility concept

Abstract: In an automated manufacturing system, performance of machining is an important characteristic that affects the production cost especially in machining processes like milling and boring. Boring is one of critical machining processes, and therefore, it is very difficult to determine overall performance of the process. In the present work, an attempt was made to maximize overall performance of the process in order to reduce reworking and production cost. Three different performance characteristics like surface roughness, tool wear and root mean square of workpiece vibration velocity are considered to determine overall performance for boring of AISI 1040 steel with carbide tool inserts. According to User's Preference Rating, weights for the three performance characteristics are calculated using graph theory and matrix approach (GTMA). Overall performance or utility value of the machining process is calculated using utility concept. A response surface methodology (RSM) is used to optimize the process parameters for maximization of performance of the process. Weights of surface roughness, tool wear and root mean square of workpiece vibration velocity are calculated as 0.489, 0.367 and 0.184 respectively. Optimum process parameters were found to be 0.4 mm of nose radius, 170 m/min of cutting speed and 0.1358 mm/rev of feed rate.

A Dense I1O3 Hybrid Superhydrophobic Network, Pb(H-BTMB), Exhibits Selectivity toward CO2 Gas Sorption

Abstract: We achieved a dense I1O3 hybrid superhydrophobic porous coordination polymer (PCP), [Pb(H-BTMB)(DMF)] (1), by solvothermal methods. The single-crystal XRD structure of 1 indicated that it has a three-dimensional M–L–M framework with one-dimensional M–O–M connectivity leading to an I1O3 network. The new PCP obtained exhibited open metal sites (OMSs) by losing a coordinated DMF molecule. The degassed phase displayed selective adsorption of CO2 gas over N2, C2H6, and C2H4 gases. Additionally, it has a superhydrophobic surface with a contact angle of 156.4° at room temperature and it is stable even at 90 °C, displaying a contact angle of 135.3°.

Distribution and fractionation of rare earth elements and Yttrium in suspended and bottom sediments of the Kali estuary, western India

Abstract: Concentrations of rare earth elements (REE) and yttrium (Y), and major metals (Al, Fe and Mn) were measured in suspended particulate matter (SPM) and bottom sediments of the Kali estuary, western India, for their distribution and fractionation. The contents of SPM and metals in it were more uniform along the longitudinal transect during the monsoon. During the post- and pre-monsoons, low SPM in the upper/middle estuary coincided with high Fe and Mn and total REE (∑REE). But in the lower estuary SPM and its ∑REE content increased seaward, while Fe and Mn decreased. The Y/Ho ratios decreased seaward during the monsoon but increased during the post-monsoon. Sm/Nd ratios were more uniform along the transect during monsoon but decreased marginally seaward in other seasons. The Post-Archean Average Australian Shale (PAAS)-normalized REE patterns exhibited middle REE and heavy REE enrichment with positive Ce ($${\text{Ce}}/{\text{Ce}}^{*}$$ ), Eu ($${\text{Eu}}/{\text{Eu}}^{*}$$ ) and Y anomalies. The $${\text{Ce}}/{\text{Ce}}^{*}$$ increased but $${\text{Eu}}/{\text{Eu}}^{*}$$ decreased marginally seaward. The fine-grained sediments showed higher ∑REE and lower Y/Ho ratios than in coarse-grained sediments. The PAAS-normalized REE patterns of sediment were similar to that of SPM. The results revealed two processes, colloidal flocculation and coagulation of metals in the low-salinity zone and an estuarine turbidity maximum in the high salinity zone. Rare earths and yttrium (REY) in SPM and sediments primarily reflected the source rock composition than that of chemical weathering. Apart from physico-chemical processes, the mineralogy and grain size of sediments controlled the distribution and fractionation of REY in the estuary.

Enhanced Performance of an Asynchronous Motor Drive with a New Modified Adaptive Neuro-Fuzzy Inference System-Based MPPT Controller in Interfacing with dSPACE DS-1104

Abstract: This paper presents a photovoltaic system with maximum power point tracking facility. Maximum power point trackers are so important in photovoltaic systems to increase their efficiency. The system consists of a photovoltaic solar module connected to a DC–DC buck–boost converter and load. The adaptive neuro-fuzzy inference system (ANFIS)-based maximum power point tracking (MPPT) controller is used to track the maximum power. DC–DC boost converter and space vector modulation-based inverter are used to provide the required supply to the load. The proposed ANFIS-based MPPT improves the system efficiency even at abnormal weather conditions. Here a lot of reduction in torque and current ripple contents is obtained with the help of ANFIS-based MPPT for an asynchronous motor drive. Also, the better performance of an asynchronous motor drive is analyzed with the comparison of conventional and proposed MPPT controller using MATLAB simulation along with experimental implementation. The experimental implementation of MPPT with hardware setup is done using dSPACE real-time controller. Data acquisition and codes of the successfully simulated model can be linked and loaded directly to the dSPACE DS-1104 controller for real-time hardware operation. The simulation and the practical results represent that the proposed system tracked the maximum power accurately and successfully under different working conditions. Practical validations are also carried out and are represented.

Optimization of nutritional components of medium by response surface methodology for enhanced production of lactase.

Abstract: Lactase has excellent applications in dairy industry and commercially this enzyme is produced from bacterial sources but not in high yields. In this work, the production of lactase was improved by designing of nutrient components in fermentation medium by one factor at a time. Lactose and yeast extract were selected as preferable carbon and nitrogen sources for lactase production with tryptophan and MgSO4 showing enhanced production. Statistical analysis proved to be a useful and powerful tool in developing optimum fermentation conditions. The individual and interactive role of lactose, yeast extract, magnesium sulfate, and tryptophan concentration on lactase production was examined by central composite design. Submerged fermentation with Bacillus subtilis strain VUVD001 produced lactase activity of 63.54 U/ml in optimized medium. The activity was threefold higher in comparison to an unoptimized medium. This result confirmed that the designed medium was useful for producing higher yields of lactase.

Congenital Hypothyroidism: Facts, Facets & Therapy.

Abstract: Background: Thyroid hormone (T3) is essential for normal development of children enabling brain development and somatic growth. However, certain individuals are genetically predisposed with insufficient or no thyroid hormones. Such a condition is termed congenital hypothyroidism (CH). Objective: In the present review, a brief back ground about congenital hypothyroidism, factors associated with CH leading to thyroid dysgenesis and thyroid dyshormonogenesis is elaborated. Additionally, the guidelines for available treatment options, management and follow-up required for patients diagnosed with CH are discussed. Treatment options in terms of treatment initiation and dosage of hormone replacement are discussed. Conclusion: Though CH is considered as the most common neonatal metabolic disorder, it is also easily treatable compared to other metabolic or hereditary diseases. The outcome of CH treatment depends on the compliance of parents early in life and by patients themselves during later part of life.

Modeling and optimization of fermentation variables for enhanced production of lactase by isolated Bacillus subtilis strain VUVD001 using artificial neural networking and response surface methodology.

Abstract: Modeling and optimization were performed to enhance production of lactase through submerged fermentation by Bacillus subtilis VUVD001 using artificial neural networks (ANN) and response surface methodology (RSM). The effect of process parameters namely temperature (°C), pH, and incubation time (h) and their combinational interactions on production was studied in shake flask culture by Box–Behnken design. The model was validated by conducting an experiment at optimized process variables which gave the maximum lactase activity of 91.32 U/ml. Compared to traditional activity, 3.48-folds improved production was obtained after RSM optimization. This study clearly shows that both RSM and ANN models provided desired predictions. However, compared with RSM (R 2 = 0.9496), the ANN model (R 2 = 0.99456) gave a better prediction for the production of lactase.

Evaluation of in Vitro Antibacterial Activity of Caralluma Lasiantha for Scientific Validation of Indian Traditional Medicine

Abstract: Caralluma lasiantha is used as a traditional medicine in India to heal body heat and inflammations. In order to find out a scientific validation for the Indian traditional knowledge, antibacterial activity of C. lasiantha extracts was studied against inflammation causing bacteria (viz., Staphylococcus aureus, Escherichia coli, Streptococcus Sp., Bacillus subtilis, Enterobacter aerogenes, Klebsiella pneumoniae) along with other Gram-positive and Gram-negative bacteria. Solvents with different polarity were used for extraction from dry roots and stems. Minimum inhibitory concentrations (MIC) were also studied. Differential antibacterial activity was exhibited by extracts and higher inhibition potential against Gram-positive bacteria was explained. The observed antibacterial activities were correlated with the chemical structures of phytochemicals present in C. lasiantha. Anti-inflammation activities are related to C. lasiantha extracts through their antibacterial activities.

Quality-by-design-based development and validation of a stability-indicating UPLC method for quantification of teriflunomide in the presence of degradation products and its application to in-vitro dissolution

Abstract: A systematic design-of-experiments was performed by applying quality-by-design concepts to determine design space for rapid quantification of teriflunomide by the ultraperformance liquid chromatography (UPLC) method in the presence of degradation products. Response surface and central composite quadratic were used for statistical evaluation of experimental data using a Design-Expert software. The response variables such as resolution, retention time, and peak tailing were analyzed statistically for the screening of suitable chromatographic conditions. During this process, various plots such as perturbation, contour, 3D, and design space were studied. The method was developed through UPLC BEH C18 2.1 × 100 mm, 1.7-µ column, mobile phase comprised of buffer (5 mM K2HPO4 containing 0.1% triethylamine, pH 6.8), and acetonitrile (40:60 v/v), the flow rate of 0.5 mL min−1 and UV detection at 250 nm. The method was developed with a short run time of 1 min. Forced degradation studies revealed that the met...

Evaluation of haplotype diversity of Achatina fulica (Lissachatina) [Bowdich] from Indian sub-continent by means of 16S rDNA sequence and its phylogenetic relationships with other global populations.

Abstract: Achatina fulica (Lissachatina fulica) is one of the most invasive species found across the globe causing a significant damage to crops, vegetables, and horticultural plants. This terrestrial snail is native to east Africa and spread to different parts of the world by introductions. India, a hot spot for biodiversity of several endemic gastropods, has witnessed an outburst of this snail population in several parts of the country posing a serious threat to crop loss and also to human health. With an objective to evaluate the genetic diversity of this snail, we have sampled this snail from different parts of India and analyzed its haplotype diversity by means of 16S rDNA sequence information. Apart from this, we have studied the phylogenetic relationships of the isolates sequenced in the present study in relation with other global populations by Bayesian and Maximum-likelihood approaches. Of the isolates sequenced, haplotype 'C' is the predominant one. A new haplotype 'S' from the state of Odisha was observed. The isolates sequenced in the present study clustered with its conspecifics from the Indian sub-continent. Haplotype network analyses were also carried out for studying the evolution of different haplotypes. It was observed that haplotype 'S' was associated with a Mauritius haplotype 'H', indicating the possibility of multiple introductions of A. fulica to India.