Display omitted
•Micro-PIV measurements for Low salinity water (LSW) flooding, polymer flooding, and alkali-polymer flooding.•Characterization of flooding process using velocity field, shear rate, ...and vorticity profiles.•Effects of contact angle, interfacial tension, and droplet size distribution on the displacement of trapped oil.•Core flooding experiments to investigate the heavy oil recovery at the core-scale.
We report a quantitative analysis of pore-scale flow dynamics and displacement behavior of heavy oil recovery at the micro and macro-scale to optimize different chemical flooding processes for enhanced heavy oil recovery. Microscopic studies are performed using micro-particle image velocimetry, which includes low saline water followed by chemical floodings in a 2D porous micromodel to visualize and quantify the displacement process and the oil recovery. The phenomena such as fluctuating flow, flow direction reversal, viscous fingering, film formation around cylinders, unsteady flow behavior, and sudden velocity jumps are observed during low salinity water flooding. Polymer flooding results in no significant change in trapped oil configuration. Alkali-polymer solution injection improves oil recovery as it interacts with crude oil, which results in higher in-situ emulsification, interfacial tension reduction, and change in the contact angle to extremely water-wet conditions. Core flooding experiments are performed to understand the macroscopic behavior and recovery potential of different flooding processes at simultaneous and separate injection modes. The core flooding results showed that the overall heavy oil recovery is 75.37% by simultaneous injection of chemical slugs; however, a separate injection of individual chemical slugs yields lower oil recovery in the case of alkali-surfactant-polymer flooding than the simultaneous injection case. Here, the combined microscopic and macroscopic study provides information about the mechanisms and oil recovery by different chemical flooding processes through the porous medium.
Plentiful work has been done for condition monitoring (CI) and fault diagnosis of fixed-axis gearboxes. However, still it is found that articles citing condition indicators for fault diagnosis of ...gearboxes are less in quantity, in academic journals, conference proceedings and technical reports. The specialty of condition indicators is to provide accurate information regarding the condition of various components at different levels of damage (initial, heavy or growing). Here, these indicators are addressed domain-wise and their characteristics are stated. The objective of this paper is to review and encapsulate this literature to provide a wide and good reference for researchers to be utilized. The structure of a fixed-axis gearbox is briefly introduced. The unique behaviors and fault characteristics of fixed-axis gearbox is recognized and studied. Investigations on the basis of statistical indicators are also summarized based on the adopted methodologies. Lastly, open problems are stated and further research prospects pointed out.
Hollow nanostructures of copper oxides help to stabilize appreciably higher electrochemical characteristics than their solid counter parts of various morphologies. The specific capacitance values, ...calculated using cyclic voltammetry (CV) and charge-discharge (CD) studies, are found to be much higher than the values reported in literature for copper oxide particles showing intriguing morphologies or even composites with trendy systems like CNTs, rGO, graphene, etc. The proposed cost-effective synthesis route makes these materials industrially viable for application in alternative energy storage devices. The improved electrochemical response can be attributed to effective access to the higher number of redox sites that become available on the surface, as well as in the cavity of the hollow particles. The ion transport channels also facilitate efficient de-intercalation, which results in the enhancement of cyclability and Coulombic efficiency. The charge storage mechanism in copper oxide structures is also proposed in the paper.
In the present investigation, GO was prepared by exfoliation of graphite using modified Hummer's method and then reduced using hydrazine hydrate (reducing agent) to produce rGO. XRD, FESEM, Raman, ...FTIR spectrophotometer and TGA were used for characterization of GO and rGO. XRD images reveal crystalline structure for both GO and rGO. The d‐spacing is observed to be reduced for rGO as compared to that for GO because of removal of oxygen containing functional groups. Raman excitation peaks were obtained for two laser wavelengths 532 and 785 nm. Ratio of intensities of D and G bands (ID/IG) increase for rGO due to increase in order by reduction, implying restoration of the p‐conjugation. The bands are narrower for rGO.TGA thermograms show a higher overall loss of weight for GO in the temperature range 0–1000 °C under N2 flow. Intensity of FTIR peaks of oxide, hydroxyl and alkoxy groups decreases significantly on reduction. FESEM image shows more corrugated surface of rGO as compared to GO. It is expected that this investigation would be useful to develop GO/rGO based gas sensors to detect minute concentration of gases.
Display omitted
•A high-performance, porous, faradaic CeO2/NiV–LDH nanocomposite is prepared.•Various components clearly reveal the strong synergistic effect for energy storage.•The CeO2/NiV-LDH ...(2:2) composite can act as electrocatalyst for methanol oxidation.•3D flowerlike Bi2O3 is synthesized and investigated as negative electrode material.•A quasi-solid-state ASC device is fabricated to examine its practicality.
High-performance electrochemical supercapacitors should demonstrate notably high energy density along with ultralong cycling life for wide commercial applications. Hence, significant efforts are being made to improve the specific capacitance as well as expand the operating voltage of the fabricated supercapacitor device. Herein, a novel quasi-solid-state asymmetric supercapacitor (ASC) device employing porous nanostructured CeO2/NiV–LDH (2:2) composite positive electrode and 3D flowerlike Bi2O3 negative electrode is reported. The positive electrode material shows an efficiently improved electrochemical feature from synergistic integration between high surface area CeO2 nanorods, and 2D NiV–LDH nanosheets with short diffusion distance for the charge carriers. In addition, the CeO2/NiV–LDH (2:2) composite acts as highly active and stable electrocatalyst when investigated for the methanol electrooxidation. The as-fabricated gel electrolyte based quasi-solid-state CeO2/NiV–LDH (2:2)//Bi2O3 ASC device exhibits an excellent and stable electrochemical performance (highest energy density of 62.5 Wh kg−1 at a power density of 1595.2 W kg−1) with long cycle life displaying 86.4% capacitance retention still after 10,000 GCD cycles. This work confirms the high suitability of the rare earth metal oxide and LDH-based composite electrode materials, as well as Bi chalcogenides, for the quasi-solid-state ASCs as proficient portable energy systems.
Since the discovery of DNA intercalating agents (by Lerman, 1961), a growing number of organic, inorganic, and metallic compounds have been developed to treat life-threatening microbial infections ...and cancers. Fused-heterocycles are amongst the most important group of compounds that have the ability to interact with DNA. DNA intercalators possess a planar aromatic ring structure that inserts itself between the base pairs of nucleic acids. Once inserted, the aromatic structure makes van der Waals interactions and hydrogen-bonding interactions with the base pairs. The DNA intercalator may also contain an ionizable group that can form ionic interactions with the negatively charged phosphate backbone. After the intercalation, other cellular processes could take place, leading ultimately to cell death. The heterocyclic nucleus present in the DNA intercalators can be considered as a pharmacophore that plays an instrumental role in dictating the affinity and selectivity exhibited by these compounds. In this work, we have carried out a revision of small organic molecules that bind to the DNA molecule via intercalation and cleaving and exert their antitumor activity. A general overview of the most recent results in this area, paying particular attention to compounds that are currently under clinical trials, is provided. Advancement in spectroscopic techniques studying DNA interaction can be examined in-depth, yielding important information on structure-activity relationships. In this comprehensive review, we have focused on the introduction to fused heterocyclic agents with DNA interacting features, from medicinal point of view. The structure-activity relationships points, cytotoxicity data, and binding data and future perspectives of medicinal compounds have been discussed in detail.
In this study, a novel thermophilic bacterial strain was isolated from Tattapani hot spring located in the Chhattisgarh state of India. The laccase was produced via submerged fermentation and ...purified by ammonium sulfate precipitation and anion exchange chromatography up to 13.7 fold. The 16S rRNA gene sequence and biochemical analysis revealed that the bacterial isolate is Bacillus sp. strain PC-3. The activity of extracellular crude laccase was determined to be 11.2 U/mL using 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) as a substrate. The SDS-PAGE revealed that the enzyme consists of single subunit with molecular size of 36 kDa. The laccase exhibited the maximum enzyme activity at temperature of 60°C and pH 7. Moreover, the laccase retained 99.1% of its original activity for 180 min and exhibited half-life of 3.75 h at 60°C. Similarly, the laccase retained 95% activity at pH 7 for 240 min and displayed significant activity at wider pH range. In addition, the laccase was used for functionalization of chitosan film and characterized for antioxidant and antimicrobial activity. Interestingly, the functionalized chitosan film showed the improved antioxidant and antimicrobial activity.
PDF
