7274 research outputs found
Sort by
Optimization study for enhanced production of hyaluronic acid from Streptococcus equisimilus MK156140
No full textHyaluronic acid finds its complete application in areas such as therapeutics, cosmetics, and as a health supplement. In the present investigation, standardization for the production of hyaluronic acid by Streptococcus equisimilus MK156140 in complex media was performed. Some of the selected physicochemical parameters such as pH, temperature, speed, incubation time, sucrose, yeast extract, and beef extract were screened using Plackett-Burman foldover design. Further, the screened parameters interaction was investigated using central composite design (CCD) and closely compared with OVAT studies. At a pH of 7.38, with beef extract, 12.15%, and yeast extract 7.64%, the observed yield was 7.16 g/L, which was in close line with the predicted value of 7.21 g/L. © 2021, The Korean Institute of Chemical Engineers
Photocatalytic and photosensitization reactions of surface modified W<sup>6+</sup> and N<sup>3‒</sup> doped TiO<sub>2</sub> with curcumin/potassium curcuminate molecules
No full textCurcumin and potassium curcuminate molecules were anchored on W6+ and N3‒ doped TiO2 catalyst (WNT) surface by wet impregnation method and were designated as Cur-WNT and K3Cur-WNT. The XPS and FTIR techniques confirm the surface anchoring of curcumin and potassium curcuminate molecules on the surface of WNT through enolate linkage. K3Cur-WNT catalyst possesses multiple charge trapping states involving dopant energy levels, inherently created defect levels/surface states. Hence the mean free path of the photogenerated electrons is decreased in this catalyst by trapping and detrapping events. The energy band positions of valence band (EVB), conduction band (ECB) and Fermi energy (EF) were determined from the electronegativity values of the atoms present in the catalyst sample and also from the valence band X-ray photoelectron spectroscopic (VBXPS) studies. Energetically the position of conduction band (CB) and W 5d dopant energy levels were found to be located below the lowest unoccupied molecular orbital (LUMO) of curcumin and potassium curcuminate molecules in Cur-WNT and K3Cur-WNT samples. This suitable excited singlet energy band position (S1) of sensitizer molecule facilitates the electron transfer process to the CB/W 5d energy levels of the WNT catalyst. The accumulated electrons in CB/W6+ dopant energy level influence the position of EF within the band gap. The observed higher quantum efficiency of K3Cur-WNT sample compared to all the other catalysts can be accounted to the narrowed band gap, generated shallow traps, reduced particle size, enhanced photosensitivity and its higher capability in generating reactive singlet oxygen species. [Figure not available: see fulltext.] © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature
Spectroscopic and theoretical investigation on the origin of color in jarosites
No full textThis work aims to understand the origin of the electronic spectra of Fe3+ (d5), Cr3+ (d3), and V3+ (d2) containing jarosites. The electronic spectrum of the Fe-jarosite is currently assigned to spin forbidden transitions. This work shows that the spectra essentially arise due to the tetragonal distortion of the coordination symmetry of the Fe3+ ion in the jarosite crystal, and thereby obviates the need for invoking spin forbidden transitions. The absorption spectra of Cr- and V-jarosite are also assigned to transitions predicted for the tetragonal distortion of the metal ion coordination. The electronic term symbols are worked out using the correlation diagram and Tanabe-Sugano diagram for orbital splitting for all three systems employing ab initio and DFT methods. The bandgaps were computed and corroborated with the experimentally measured values to support the low symmetry at the metal center. © 2021 Elsevier B.V
Carbon nanotubes-based hydrogels for bacterial eradiation and wound-healing applications
No full textBiocompatible nanomaterials have attracted enormous interest for biomedical applications. Carbonaceous materials, including carbon nanotubes (CNTs), have been widely explored in wound healing and other applications because of their superior physicochemical and potential biomedical properties to the nanoscale level. CNTs-based hydrogels are widely used for wound-healing and antibacterial applications. CNTs-based materials exhibited improved antimicrobial, antibacterial, adhesive, antioxidants, and mechanical properties, which are beneficial for the wound-healing process. This review concisely discussed the preparation of CNTs-based hydrogels and their antibacterial and wound-healing applications. The conductive potential of CNTs and their derivatives is discussed. It has been observed that the conductivity of CNTs is profoundly affected by their structure, temperature, and functionalization. CNTs properties can be easily modified by surface functionalization. CNTs-based composite hydrogels demonstrated superior antibacterial potential to corresponding pure polymer hydrogels. The accelerated wound healing was observed with CNTs-based hydrogels
Production of biogas from human faeces mixed with the co-substrate poultry litter & cow dung
No full textIn general, human faeces disposal in India is into open lands, nallahs and rivers without treatment and has very high content of nutrients, organic matter and pathogens. Human faeces can cause adverse environmental and health problems (due to pathogen contamination, odor etc.) in the absence of appropriate disposal methods. This study was carried out to compare the rate and amount of biogas produced from co-digestion of human faeces (HF) with poultry litter (PL) & cow dung (CD) under anaerobic conditions. A laboratory scale simulation digesters (D) was set up with three different proportions of substrate i.e D1–100% HF, D2- 50:50 HF+PL and D3- 40:60 HF+CD and the study carried out for 52 days at room temperature between 25 to 35 °C. In each case, the feedstock was diluted with equal volume of water to form slurry. The daily biogas production for each anaerobic digester was recorded using the water displacement method, and the corresponding cumulative biogas volume was calculated. The result obtained from this study shows that a total of 7.62 × 103 ml, 9.85 × 103 ml and 12.96 × 103 ml of biogas were produced from HF, HF+PL and HF+CD, respectively. Thus, the co-digestion of human faeces with cow dung (HF+CD) gave a better biogas production may be due to the maximum COD reduction and optimum C/N ratio as well as fast bacterial action on cow dung relative to the poultry litter and human faeces. Pathogen inactivation was inefficient after the anaerobic digestion of waste as the reduction in the number of E. coli and Enterobacteriaceae was only by one logarithmic unit The highest biogas yields were observed at pH 7.52, 7.9 and 7.63 for HF, HF+PL and HF+CD, respectively. The COD reductions were 42.97, 47.5 and 52.99%, for D1 (HF), D2 (HF+PL), and D3 (HF+CD) digesters, respectively. To control spread of human faeces disease and protect fragile environment, it can be used for biogas production, combustion as fuel, biochar production, in building materials and as a soil conditioner. © 2021 Elsevier B.V
TLC directed isolation and in silico analysis of antimicrobial metabolite from Nigrospora sphaerica inhabiting Croton bonplandianus Baill
No full textTLC-bioautography amalgamated with hyphenated spectroscopy aid in precise in situ detection of secondary metabolites with pharmaceutical significance. TLC bioautography offers efficient and economical strategy in identifying compounds of interest from crude extracts. The present investigation has been focused on detection of antimicrobial metabolite from the culture broth of Nigrospora sphaerica inhabiting Croton bonplandianus Baill. The antimicrobial profiling confirmed the bioactive nigrosporalactone to possess broad-spectrum activity against test human pathogens with minimum inhibitory concentration values in the range 6.25 µg to 100 µg. The in silico studies revealed protein targets 1I01 (E. coli beta-ketoacyl reductase), 1IYL (C. albicans N-myristoyl transferase) had the highest binding score of -6.1 Kcal/mol. © 2021 SAA
Novel Functional Matrix Method using Standard Basis of Polynomial Linear Space
No full textThis paper has developed a novel functional matrix using the standard basis of (n+1) dimensional polynomial linear space to solve second-order singular initial and boundary problems. The linearly independent polynomials properties are used to convert the differential equations into algebraic equations with suitable solvers that can efficiently solve. Seven numerical examples are considered to demonstrate this technique's applicability and efficiency. The obtained results are compared favorably with the exact solutions. Also, we proved some theorems on convergence, exact solutions, and uniform convergence