Diversity of Catechin in Northeast Indian Tea Cultivars

Tea (Camellia sinensis L.) leaf contains a large amount of catechins (a group of very active flavonoids) which contribute to major quality attributes of black tea. Based on morphological characters tea plants were classified as Assam, China, and Cambod varieties. The present study is an attempt for biochemical fingerprinting of the tea varieties based on catechin composition in green leaf of cultivars grown in Northeast India. Assam variety cultivars contained the highest level of catechins followed by Cambod and China. The average catechin contents were 231 ± 7 mg g−1, 202 ± 5 mg g−1, and 157 ± 4 mg g−1 of dry weight of green leaf for Assam, Cambod, and China cultivars, respectively. Among the individual catechins the variations in epigallocatechin gallate (EGCG) and epigallocatechin (EGC) were the most prominent among the varieties. High EGC content was found to be a characteristic of Assam variety which was further corroborated through multivariate analysis

Discrimination of green tea using an Epigallocatechin-3-gallate (EGCG) sensitive molecular imprinted polymer (MIP) based electrode

In this work, a simple approach of discriminating green tea samples has been proposed using an epigallocatechin-3-gallate (EGCG) sensitive molecular imprinted polymer (MIP) electrode modified with chemically synthesized nickel hydroxide (Ni(OH)2) nanoparticles. The nanoparticles were characterized by powder X-ray diffraction techniques (XRD) and the removal of the template molecule has been ascertained by UV-vis spectroscopy. A three electrode system has been employed to study the electrochemical characteristics of the electrode by means cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Four different kinds of preprocessing techniques, namely – (i) Baseline subtraction, (ii) Autoscale, (iii) Relative scale 1 and (iv) Relative scale 2 were applied on the obtained data set and the best preprocessing technique was optimized. Further, principal component analysis (PCA) and linear discriminant analysis (LDA) were implemented on the preprocessed data set so as to observe the discrimination ability of the electrode on the basis of EGCG content in green tea. The separability index (SI) values for both PCA and LDA plots is calculated and it is observed that baseline subtraction provided the best result with a SI value of 8.72 and 16.01, respectively

Improved rheology and high-temperature stability of hydrolyzed polyacrylamide using graphene oxide nanosheet

Hydrolyzed polyacrylamide (HPAM) is a polymer that extensively used in chemical industry and hydrocarbon extraction and refinery processes, but suffers a common problem of high-temperature instability. This study improved high-temperature rheological characteristics of HPAM by using novel graphene oxide (GO) nanosheets. Stable GO dispersions in aqueous HPAM were formulated, and their dynamic and viscoelastic behaviors were studied. The results showed that the addition of GO significantly increased the viscosities and high-temperature stability of the base polymer fluid, as well as the elastic properties of the dispersion. Spectral data indicated the formation of covalent linkages and electrostatic hydrogen bonding between the GO and the HPAM functional groups, leading to enhanced stability and viscosity that is beneficial for high-temperature oil recovery. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47582

Prime and Punishment

An online experiment carried out on Psytoolkit to gauge the effect of religious priming and group membership on prosocial behavior

Application of Chicory as Corrosion Inhibitor for Acidic Environments

Summary During acidizing stimulation or cleanup operations, metal tubulars, downhole tools/valves, and surface lines are exposed to acidic fluids and are prone to corrosion. Because corrosion rates drastically increase in high-temperature wells, controlling corrosion is critical and must be dealt with carefully. In addition, corrosion protection is important for maintaining the integrity and long life of downhole tools installed in a well. Several corrosion inhibitors, such as quaternary ammonium compounds and propargyl alcohol-based compounds, have been effectively used in the industry. However, because of stringent environmental regulations, attention has focused on the development of new corrosion inhibitors that are environmentally benign. Food-grade products that are considered "green" chemicals have significant potential as corrosion inhibitors in the oil and gas industry. In this paper, application of chicory as a corrosion inhibitor for high-temperature and strong-acidic conditions is discussed. Chicory is a perennial bush plant available in many parts of the world. The root of the chicory plant can be roasted and ground for use as a coffee substitute or additive. Chicory is environmentally acceptable and, being of plant origin, is widely recognized as biodegradable in nature. This study shows that chicory can provide corrosion protection for alloys such as N-80, 13Cr-L80, and 1010 steel in the presence of either inorganic or organic acids at temperatures up to 250°F (121°C). Considering its performance and lack of toxicity issues, chicory has significant potential for acid corrosion-inhibition applications. The mixing procedure for preparing the blend, experimental setup and test procedure, and laboratory results of high-pressure/high-temperature (HP/HT) corrosion tests are discussed.</jats:p

High-Temperature Acidizing: Advantages of Inhibitor-Intensifier Synergy

Abstract High-temperature acidizing operations are challenging because of the highly corrosive nature of acids. Hydrochloric (HCl) acid has an especially high reaction rate, which increases the rate of tubular corrosion. In addition to the type and concentration of acids, factors such as temperature and metallurgy influence the rate of corrosion. To meet increasing demand for deeper stimulation at high temperatures, emulsified acid is predominately used. It contains acid in the internal phase and oil in the external phase, forming an invert emulsion. The outer oil phase creates a barrier for acid, allowing its slow release for reaction with reservoir rock. Emulsified acid systems provide several advantages compared to plain acid. The oil barrier especially helps with preventing corrosion by significantly reducing the contact of acid with the metal tubular. High fluid viscosity helps reduce fluid loss, distributes the acid more uniformly in the formation, and reduces the rate of corrosion. Selection of the proper corrosion inhibitor(s) is one of the most important criteria for high-temperature acidizing. The use of intensifier(s) with the inhibitor enhances the corrosion inhibition significantly. This makes it possible to use a higher concentration of HCl acid at temperatures as high as 350°F, thus enhancing the fluid efficiency. In this work, several corrosion inhibitors and intensifiers are studied at varied acid strengths and temperature conditions. To achieve good corrosion control, a synergy is required between corrosion inhibitors and corrosion inhibitor intensifiers. At the same time, they should not negatively impact the emulsion stability. A new emulsified acid system was developed using HCl acid strength up to 28%. High corrosion control imparted by inhibitor-intensifier synergy coupled with the slow reaction rate of emulsified acid makes this blend unsurpassed for use in extreme high-temperature conditions up to 350°F. This emulsified acid system has the potential for use in the Khuff formation of Saudi Arabia with the addition of a H2S scavenger. Testing with a commercially available scavenger exhibited good compatibility with the blend.</jats:p

Novel High Viscus Acid System for Proppant Fracture Acidizing

Abstract Production decline in acid-fractured reservoirs result from the elastic, plastic, and creeping response of highly confined vertical stresses that can destroy the conductive channels created by the acid. This paper introduces a novel, highly viscous acid system having the potential to suspend proppant and perform simultaneous acid and proppant fracturing treatments. During production, impure carbonates tend to decrease productivity as quartz and other minerals migrate, leading to channel closing and/or collapse. Conventionally, acid fracturing treatments are performed by fracturing without proppant followed by different acid stages, including gelled acid. The idea of proppant-fracturing-acidizing (PFA) system entails fracturing in a single stage operation, although to avoid post-treatment plugging of the propped fractures the application of the process would be limited to very clean carbonates. This paper describes PFA fluid prepared by emulsifying hydrochloric acid (HCl) in the internal phase using diesel as the external phase. PFA offers distinct advantages compared to conventional acid systems, namely high viscosity to carry proppant, simultaneously acid-etching the rock, while attaining deeper live acid penetration. Another potential advantage is lowering operational time because mixing can be performed on-the-fly. Preliminary experimental studies have been carried out to investigate the performance of PFA fluid and validate its applicability to perform simultaneous acid and proppant fracturing. PFA was prepared at various HCl concentrations and tested up to 28%. PFA fluid viscosity under different shear rates was measured at high-pressure/high-temperature (HP/PT). It exhibited viscosity as high as 2424 cp at 100°F and 300 cp at 300°F at 50 1/s shear rate. The oil external nature and the stability of the PFA fluid were examined using HP/HT autoclaves at 300°F. The effectiveness of corrosion inhibitors in PFA fluid was determined at 300°F. Static proppant settling tests showed that PFA fluid has good proppant carrying capacity at different particle loadings. After spending PFA fluid in carbonate, the viscosity was reduced significantly, exhibiting breaker-free cleanup. Carbonate reservoirs having closure stress of more than 5,000 psi could be propped to enhance conductivity using PFA system. Enhancing the stimulated reservoir volume could be plausible using PFA system as a single-fluid treatment option, particularly if acid leakoff control and diversion, deeper penetration, and acid and proppant fracturing can be simultaneously implemented.</jats:p