Acid Reagent Research Articles

One-Step Protein–Polymer Conjugates from Boronic-Acid-Functionalized Polymers

Polymer-protein conjugates are hybrid materials with interesting and useful properties. Methods to prepare diverse diblock materials of this sort often struggle to deal with the complexity and size of reagents, and so polymer-protein conjugation represents a stringent testing ground for nontraditional bioconjugation methods, such as metal-catalyzed arylation. This work demonstrates a simple Ni2+-promoted arylation of cysteine residues with end-functionalized polymer-boronic acid reagents, and explores some molecular and physical properties possible in these hybrid structures.

Full-color fluorescent carbon quantum dots.

Quantum dots have innate advantages as the key component of optoelectronic devices. For white light-emitting diodes (WLEDs), the modulation of the spectrum and color of the device often involves various quantum dots of different emission wavelengths. Here, we fabricate a series of carbon quantum dots (CQDs) through a scalable acid reagent engineering strategy. The growing electron-withdrawing groups on the surface of CQDs that originated from acid reagents boost their photoluminescence wavelength red shift and raise their particle sizes, elucidating the quantum size effect. These CQDs emit bright and remarkably stable full-color fluorescence ranging from blue to red light and even white light. Full-color emissive polymer films and all types of high-color rendering index WLEDs are synthesized by mixing multiple kinds of CQDs in appropriate ratios. The universal electron-donating/withdrawing group engineering approach for synthesizing tunable emissive CQDs will facilitate the progress of carbon-based luminescent materials for manufacturing forward-looking films and devices.

General High-Pressure Closed Acidic Decomposition Method of Rock Samples for Trace Element Determination Using Inductively Coupled Plasma Mass Spectrometry

Complete decomposition is an essential prerequisite for accurate trace element quantification in geological samples. This work presents a general high-pressure closed digestion approach for rock samples from basic to acidic rocks by inductively coupled plasma mass spectrometry. Using HNO3−HF mixed system, different geological reference materials have been investigated for trace element determination, with acid ratio, decomposition time, digestion temperature, sample mass and reagent amount discussed in detail. In brief, 2.0 mL of HNO3−HF with the ratio of 1 : 1 and a digestion time of 12 h at 185°C in high-pressure sealed bomb are optimal for 50 mg rock sample decomposition. With relative errors under 10%, the analytical results of W-2a, BCR-2, GSP-2, AGV-2 and GSR-1 agree well with certified values. This proposed high-pressure sealed digestion method is characterized with less acid consumption, complete digestion and less damage for digestion process, well meeting the requirements for large sample throughput in geological laboratory.

Using wastes of buckwheat processing as sorption materials for the removal of pollutants from aqueous media: a review

Based on data from various literature sources, information is given on the chemical composition of straw and husk of buckwheat grains. The information on buckwheat processing waste as a source for obtaining various valuable components is provided. Literature data on the use of ground buckwheat straw as a sorption material for the extraction of heavy metal ions and oil products from natural and sewage are presented. The possibility of increasing sorption characteristics by buckwheat straw treatment with various chemical reagents is shown. Determined that the husk of buckwheat grains contains cellulose and lignin most of all. Information is given on the use of the fruit shells of buckwheat grains as sorption materials for the removal of metal ions, oil and oil products from aqueous media. It was shown that to increase the sorption characteristics of these pollutants is possible by treating the sorption material with acidic chemical reagents and high-frequency low-pressure plasma. The parameters of acid treatment or plasma exposure are determined at which the highest adsorption indicators. Native straw and buckwheat husk are effective sorption materials for the removal of heavy metal ions and oil from aqueous media. It is possible to increase the sorption characteristics according to pollutants by a chemical or physical and chemical modification.

Underway Measurement of Dissolved Inorganic Carbon (DIC) in Estuarine Waters

Dissolved inorganic carbon (DIC) is an important parameter of the marine carbonate system. Underway analyses of DIC are required to describe spatial and temporal changes of DIC in marine systems. In this study, we developed a microvolume flow detection method for the underway determination of DIC in marine waters, using gas-diffusion flow analysis in conjunction with electrical conductivity (EC) measurement. Only an acid carrier reagent (0.2 mol.L−1) and an ultrapure water acceptor are required for the DIC monitoring system. In this system, a sampling loop (100 µL) is used to quantify the injection sample volume, allowing micro-sample volume detection. The water sample reacts with the acid reagent to convert carbonate and bicarbonate species into CO2. The water sample is then carried into a gas-diffusion assembly, where the CO2 diffuses from the sampling stream into the acceptor stream. CO2 in the acceptor is detected subsequently by an electrical conductivity. The limit of DIC detection using ultrapure water is 0.16 mM. A good repeatability is obtained, with a relative standard deviation (RSD) of 0.56% (1 mM, n = 21). The time interval for detecting one sample is 5 min. During the observation period, measurements can be switched between standard solutions and water samples automatically. Accuracy and precision of the instrument is sufficient for the underway observation of marine DIC in estuarine waters.

Five Novel Non-Sialic Acid-Like Scaffolds Inhibit In Vitro H1N1 and H5N2 Neuraminidase Activity of Influenza a Virus.

Neuraminidase (NA) of influenza viruses enables the virus to access the cell membrane. It degrades the sialic acid contained in extracellular mucin. Later, it is responsible for releasing newly formed virions from the membrane of infected cells. Both processes become key functions within the viral cycle. Therefore, it is a therapeutic target for research of the new antiviral agents. Structure–activity relationships studies have revealed which are the important functional groups for the receptor–ligand interaction. Influenza virus type A NA activity was inhibited by five scaffolds without structural resemblance to sialic acid. Intending small organic compound repositioning along with drug repurposing, this study combined in silico simulations of ligand docking into the known binding site of NA, along with in vitro bioassays. The five proposed scaffolds are N-acetylphenylalanylmethionine, propanoic 3-[(2,5-dimethylphenyl) carbamoyl]-2-(piperazin-1-yl) acid, 3-(propylaminosulfonyl)-4-chlorobenzoic acid, ascorbic acid (vitamin C), and 4-(dipropylsulfamoyl) benzoic acid (probenecid). Their half maximal inhibitory concentration (IC50) was determined through fluorometry. An acidic reagent 2′-O-(4-methylumbelliferyl)-α-dN-acetylneuraminic acid (MUNANA) was used as substrate for viruses of human influenza H1N1 or avian influenza H5N2. Inhibition was observed in millimolar ranges in a concentration-dependent manner. The IC50 values of the five proposed scaffolds ranged from 6.4 to 73 mM. The values reflect a significant affinity difference with respect to the reference drug zanamivir (p < 0.001). Two compounds (N-acetyl dipeptide and 4-substituted benzoic acid) clearly showed competitive mechanisms, whereas ascorbic acid reflected non-competitive kinetics. The five small organic molecules constitute five different scaffolds with moderate NA affinities. They are proposed as lead compounds for developing new NA inhibitors which are not analogous to sialic acid.

Yeşil çay ekstresinin soğuk muhafaza koşullarında depolanan levrek (Dicentrarchus labrax) filetolarında kaliteye etkisi

Despite its high nutritional value, antioxidants are used in aquaculture products that have a short lifetime, as in other foods, to maintain quality during preservation. The purpose of this study; It is to observe the oxidative stability of sea bass (Dicentrarchus labrax) fillets at 0-4 ℃ using green tea extract obtained by classical brewing method, which is a method that can be applied by the consumer with ease. Determined concentrations (0.4-0.8-1.2 g / ml) and immersion times (10-20 min) green tea extract is applied and the fillets stored at 0-4 Thiobarbituric acid reagents (TBARs) analysis, sensory analysis and color analysis were performed on days 0, 3, 6 and 9 of storage. Depending on the literature, although no significant effect is expected, total aerobic mesophilic bacteria (TAMB) analysis was also performed additionally. As a result of the analyzes, significant differences were found when the TBARs results of all samples with green tea extract applied were compared with the results of the control group after 9 days of storage (p &lt;0.05). At the end of storage, the 4th group (0.8% g / ml-20min) gave the best results with 0.31 ± 0.009 μ mol MDA / g and there is a significant difference was found between the other groups (p &lt;0.05). Green tea extract; As expected, it was determined that it did not have a significant antimicrobial and sensory effect. The color values caused a negative increase in the a * value, which expresses its green color as expected due to the color substances in its content, and a positive increase in the b * values, which express the yellow color. As a result of this study, it was found that green tea extract can be used as natural antioxidant in sea bass fillets.

One-pot, room-temperature conversion of dinitrogen to ammonium chloride at a main-group element.

The industrial reduction of dinitrogen (N2) to ammonia is an energy-intensive process that consumes a considerable proportion of the global energy supply. As a consequence, species that can bind N2 and cleave its strong N-N bond under mild conditions have been sought for decades. Until recently, the only species known to support N2 fixation and functionalization were based on a handful of metals of the s and d blocks of the periodic table. Here we present one-pot binding, cleavage and reduction of N2 to ammonium by a main-group species. The reaction-a complex multiple reduction-protonation sequence-proceeds at room temperature in a single synthetic step through the use of solid-phase reductant and acid reagents. A simple acid quench of the mixture then provides ammonium, the protonated form of ammonia present in fertilizer. The elementary reaction steps in the process are elucidated, including the crucial N-N bond cleavage process, and all of the intermediates of the reaction are isolated.

Isolation and identification of antibacterial compound from common name Holothuria leucospilota in the Persian Gulf

Echinodermata are one of the most important branches of invertebrate in marine ecosystems, which today are also known as a rich source of natural products with biological properties. Most of these properties belong to compounds with a terpenoid structure. According to the biological properties of sea cucumbers in the Persian Gulf, this scientific study investigates the antibacterial properties of lanosterol compounds extracted from Holothuria leucospilota of Hengam Island in Persian Gulf. The cucumber powder was extracted using acetone, then the extract purified by silica gel column chromatography with n-hexane and ethyl acetate combination to isolate the terpenoid compounds. Isolated compound were run through TLC and sprayed with vanillin-sulphuric acid reagent for detection of terpenoid compound and profile of isolated compound obtained by gas chromatography (GC). The lanosterol triterpenoid compound in column fraction was identified by GC. Antimicrobial properties were evaluated by dilution test on bacterial strain Escherichia coli, Pseudomonas aeruginosa, Klebsiella nemonya, Proteus vulgaris, Salmonella typhi, Staphylococcus aureus, Bacillus subtilis, Bacillus cereus and Nocardia brazilinus. This compound has antibacterial effects on gram-positive bacteria (Bacillus subtilis, Bacillus cereus and Staphylococcus aureus). Antibacterial effects of the lanosterol indicate that it can be very effective in antibiotics production.

Isolation and identification of antibacterial steroid compounds from Ulva fasciata in the Persian Gulf

Due to numerous reasons, marine-obtained resources have attracted the interest of researchers. One of the subjects attracted the interest of researchers in recent years in the field of biologist marine algae due to their nutritional value, their benefits for health and their biological activities. In this study, the powder was extracted using acetone, then the extract purified by silica gel column chromatography with n-hexane and ethyl acetate combination to isolate the steroid compounds. Isolated compound was run through TLC and sprayed with vanillin-sulphuric acid reagent to detect the steroid compounds and profile of isolated compounds obtained by gas chromatography (GC). Antibacterial activity of steroids extracted of green algae Ulva fasciata from Qeshm Island in the Persian Gulf were assessed (in vitro). The antibacterial activity of the fractions was determined by Broth Dilution Methods against clinical Gram-negative bacteria: Escherichia coli,Pseudomonas aeruginosa, Salmonella. typhi and Gram-positive bacteria: Staphylococcus aureus, Bacillus subtilis, Bacillus cereus. The steroids; cholest-7-en-3ol and cholestan-3-one, cyclic 1, 2-ethanediyl acetal compounds in column fraction were identified by GC. The results showed the minimum bactericidal concentration (MBC) of the cholest-7-en-3ol and cholestan-3-one, cyclic 1,2-ethanediyl acetal for S. aureus and Bacillus cereus were 500 μg mL-1, the MBC of the cholest-7-en-3ol for B. subtilis was 500 μg mL-1 and 1000 μg mL-1 detected for cholestan-3-one, cyclic 1,2-ethanediyl acetal. The compounds had neither antibacterial activity on gram negative bacteria. Based on our results, extracted steroids from U. fasciata can be considered as a source of novel antibiotics.

Сircaea lutetiana l. өсімдігінің полифенолды қосылыстарының зерттелуі

One of the renewable sources of plant material is the plants of the Onagraceae L. family, growing on the territory of the Republic of Kazakhstan. The plant Circaea lutetiana L., (bipartite of Paris) of the genus Circaea L., (bipartite) of the family Onagraceae L., (fireweed), which belongs to medicinal, dyeing and food plants, was taken as an object of study. The presence of polyphenolic compounds was detected by paper chromatography in an ascending manner in solvent systems: butanol-acetic acid-water (BAW) (41:5), (40:12.5:29), 2%, 15% acetic acid with specific developers: diazotized sulfanilic acid (DZSA), diazotized para-nitroaniline (DZPNA), ammonia vapors, aluminum chloride (AlCl3), ferric chloride (FeCl3), ammonium-iron alum (AIA), vanillin reagent in sulfuric acid. The content of gallic and ferulic acids was determined in the roots and fruits of the plant, and ellagic acid in the leaves and fruits. Flavonoids and tannins of the hydrolyzable type were found in all plant organs, the largest number of them in fruits and the smallest in roots. Using the method of spectrophotometry in all plant organs, the content of flavonoids in terms of State standard sample (SSS) quercetin was determined (roots 0.96%, stems 2.03%, leaves 2.74%, fruits 3.67%), the content of tannins in terms of tannin (roots 0.005%, stems 1.19%, leaves 3.69%, fruits 5.99%).

Spectrophotometric Assay of Piperazine hexahydrate in Pharmaceutical Formulation with 3,5- Dinitrosalysilic Acid Reagent

Spectrophotometric Assay of Piperazine hexahydrate in Pharmaceutical Formulation with 3,5- Dinitrosalysilic Acid Reagent

The role of mandible injury in the pathogenesis of biochemical and functional liver disorders caused by acute blood loss and two-hour ischemia of limbs, and the efficiency of their correction by carbacetam

Introduction. In the modern world, the prevalence of gunshot wounds has increased significantly. The main cause of death under conditions of gunshot wounds is acute massive blood loss from the extremities. Applying hemostatic tourniquet according to these conditions belongs to the basic aid measures for the wounded on the battlefield. In the structure of gunshot wounds, despite the injury of the extremities, has recently significantly increased the frequency of frontal part injuries of the skull, which remains the least protected part of the body of combatants. There are lesions of the face and facial skeleton in a third of cases with such injuries. However, the effect of mandibular fracture on systemic disorders of acute blood loss complicated by two-hour ischemia-reperfusion of the limb, practically not studied, there are no data on the effectiveness of carbacetam in the case of these conditions.Objective of research: to determine the role of mandibular injury in the pathogenesis of metabolic and functional disorders of the liver caused by acute blood loss and two-hour ischemia of the limb, and to establish the effectiveness of their correction with carbacetam.Materials of the research and their discussion. The experiments were performed on 106 nonlinear male rats weighing 200-220 g. All animals were divided into four groups: control and three experimental. In the first experimental group, the animals were modeled acute blood loss (20% of the circulating blood volume) by intersection of the femoral vein. Ischemia-reperfusion of the limb was simulated on the adjacent thigh by applying a strip of elastic tourniquet "SWAT-T" (USA)10 mm wide for 120 minutes proximately on the left foot. In the second experimental group, animals with acute blood loss and ischemia-reperfusion of the limb, a fracture of mandible from the left was additionally simulated. In the third experimental group, animals with acute blood loss, ischemia-reperfusion of the limb and mandibular fracture for corrective purposes were intraperitoneally administered carbacetam at a dose of 5 mg per kilogram of animal weight.After 1 and 2 hours, as well as after 1, 7 and 14 days in experimental animals were determined indicators of bile-forming, biliary and absorption-excretory function of the liver. Liver homogenate was used to determine the content of thiobarbituric acid reagents (TBA-active LP products), catalase activity, antioxidant-prooxidant index (API) was calculated, and alanine aminotransferase (ALT) activity was determined in serum.Result of the research and their discussion. It is established that modeling of acute blood loss complicated by ischemia-reperfusion of the limb is accompanied by increased intensity of lipid peroxidation processes in the liver, depletion of antioxidant protection with a shift of antioxidant-prooxidant balance towards the strengthening of prooxidant mechanisms. This leads to increased cytolysis and the formation of liver disorder, which is manifested by a slowdown in the formation of total bile acids and the rate of bile secretion with a maximum after 1 day of observation.In the case of these conditions, additional fracture of the mandible contributes to the deterioration of the biochemical and functional state of the liver with a maximum of 1-7 days of observation. By 14 days, the indicators improve, but do not reach the level of control.Thus, a fracture of the mandible exacerbates the severity of systemic disorders caused by acute blood loss and ischemia-reperfusion of the limb. The use of carbacetam under these conditions caused a significant decrease in the content of TBA-active products in the liver, an increase in catalase activity and the value of API after 7-14 days of use. There is also a decrease in the activity of ALT in the blood serum, an increase in the content of total bile acids in the bile, the rate of bile excretion and a decrease in the duration of excretion of bromosulfalein.Conclusions: Additional simulation of mandibular fracture on the background of acute blood loss and ischemia-reperfusion of the limb is accompanied by a deepening of metabolic and functional disorders in the liver. The use of carbacetam for 7-14 days in the reperfusion period for animals with acute blood loss, ischemia-reperfusion of the limb and mandibular fracture, compared with animals without correction, causes a significant decrease in the intensity of lipid peroxidation and cytolysis, less depletion of bile-forming, biliary and absorption -excretory function of the liver.

Identification of Phosphatidylcholine Isomers in Imaging Mass Spectrometry Using Gas-Phase Charge Inversion Ion/Ion Reactions.

Gas-phase ion/ion reactions have been enabled on a commercial dual source, hybrid QhFT-ICR mass spectrometer for use during imaging mass spectrometry experiments. These reactions allow for the transformation of the ion type most readily generated from the tissue surface to an ion type that gives improved chemical structural information upon tandem mass spectrometry (MS/MS) without manipulating the tissue sample. This process is demonstrated via the charge inversion reaction of phosphatidylcholine (PC) lipid cations generated from rat brain tissue via matrix-assisted laser desorption/ionization (MALDI) with 1,4-phenylenedipropionic acid (PDPA) reagent dianions generated via electrospray ionization (ESI). Collision-induced dissociation (CID) of the resulting demethylated PC product anions allows for the determination of the lipid fatty acyl tail identities and positions, which is not possible via CID of the precursor lipid cations. The abundance of lipid isomers revealed by this workflow is found to vary significantly in different regions of the brain. As each isoform may have a unique cellular function, these results underscore the importance of accurately separating and identifying the many isobaric and isomeric lipids and metabolites that can complicate image interpretation and spectral analysis.

Clinical Post-operative Bleeding During Minor Oral Surgical Procedure and In Vitro Platelet Aggregation in Patients on Aspirin Therapy: Are they Coherent?

The risk of excessive bleeding prompts physicians to discontinue aspirin in patients on low-dose, long-term therapy which in turn puts them at the risk from adverse cardiovascular and thrombotic events. Effect of low-dose aspirin therapy on platelet function was assessed using platelet aggregation method. The aim was to correlate the laboratory platelet function with cutaneous and clinical oral bleeding time (BT). One hundred one patients were enrolled in this prospective trial and were allocated into two groups. Interventional or test group consisted of patients who were on aspirin therapy (75mg/100mg) for primary or secondary prevention of angina, myocardial infarction and stroke. Minor oral surgical procedure was performed in this group without discontinuing aspirin therapy. Control group consisted of healthy patients (under no medication) undergoing minor oral surgical procedure. Cutaneous and clinical oral BT were recorded in both the groups. Venous blood sample was drawn, and percentage platelet aggregation function was analysed using adenosine diphosphate (ADP) and arachidonic acid (AA) reagents. The percentage of platelet aggregation was then correlated with cutaneous and clinical oral BT. A significant decrease in percentage platelet aggregation using ADP (aspirin-74.7 21.39; control-89.2 13.70) and AA (aspirin-47.6 23.11; control-82.3 20.17) was observed. However, there were no significant difference in mean cutaneous BT (aspirin-1.5 0.65min; control-1.6 0.71min) and clinical oral BT (aspirin-5.0 2.48min; control-4.8 2.60min) in aspirin and control groups. Majority of the minor oral surgical procedures can be carried out safely without discontinuing aspirin in patients on low-dose long-term therapy. This is possible because despite significant platelet aggregation evident in laboratory evaluation there is lack of its clinical corroboration owing to aspirin resistance. CTRI/2018/02/012055.

An Irgafos® 168 story: When the ubiquity of an additive prevents studying its leaching from plastics

Plastic pollution is a source of chemical to the environment and wildlife. Despite the ubiquity of plastic pollution and thus plastic additive in the environment, plastic additives have been studied to a limited extend. As a prerequisite to a study aiming to evaluate the leaching of a common additive used as an antioxidant (Irgafos® 168) from polyethylene microparticles, an inventory of the potential background contamination of the laboratory workplace was done. In this study, Irgafos® 168 (tris(2,4-ditert-butylphenyl) phosphite) and its oxidized form (tris (2,4-ditert-butylphenyl) phosphate) were quantified in different laboratory reagents, including the plastic packaging and the powders, using Pyrolysis-GC/MS. At least one form of Irgafos® 168 was detected in all tested laboratory reagents with higher concentrations in caps and bottles as compared to the powders. Additionally, oxidized Irgafos® 168 was also found in the reverse osmosed and deionized water container used in the laboratory. The same profile of contamination, i.e. higher concentration of the oxidized form and higher concentrations in acidic reagents, was observed when comparing the reagent and their respective containers suggesting that the additive is leaching from the container into the powder. Overall, this study demonstrates that the antioxidant additive Irgafos® 168 is ubiquitous in the laboratory workplace. Plastic additives such as Irgafos® 168 can therefore largely interfere and biased ecotoxicological and toxicological studies especially using environmentally relevant concentrations of microplastics. The source, fate and effects of plastic additive from plastic debris should be carefully considered in future studies that require setting up methods to overcome these contaminations.

New Twists in Nazarov Cyclization Chemistry.

The defining feature of the Nazarov cyclization is a 4π-conrotatory electrocyclization, resulting in the stereospecific formation of functionalized cyclopentanones. The reaction provides access to structural motifs that are found in many natural products and drug targets. Harnessing the full potential of the Nazarov cyclization broadens its utility by enabling the development of new methodologies and synthetic strategies. To achieve these goals through efficient cyclization design, it is helpful to think of the reaction as a two-stage process. The first stage involves a 4π-electrocyclization leading to the formation of an allylic cation, and the second stage corresponds to the fate of this cationic intermediate. With a complete understanding of the discrete events that characterize the overall process, one can optimize reactivity and control the selectivity of the different Stage 2 pathways.In this Account, we describe the development of methods that render the Nazarov cyclization catalytic and chemoselective, focusing specifically on advances made in our lab between 2002 and 2015. The initial discovery made in our lab involved reactions of electronically asymmetric ("polarized") substrates, which cyclize efficiently in the catalytic regime using mild Lewis acidic reagents. These cyclizations also exhibit selective eliminative behavior, increasing their synthetic utility. Research directed toward catalytic asymmetric Nazarov cyclization led to the serendipitous discovery of a 4π-cyclization coupled to a well-behaved Wagner-Meerwein rearrangement, representing an underexplored Stage 2 process. With careful choice of promoter and loading, it is possible to access either the rearrangement or the elimination pathway. Additional experimental and computational studies provided an effective model for anticipating the migratory behavior of substiutents in the rearrangements. Problem-solving efforts prompted investigation of alternative methods for generating pentadienyl cation intermediates, including oxidation of allenol ethers and addition of nucleophiles to dienyl diketones. These Nazarov cyclization variants afford cyclopentenone products with vicinal stereogenic centers and a different arrangement of substituents around the ring. A nucleophilic addition/cyclization/elimination sequence can be executed enantioselectively using catalytic amounts of a nonracemic chiral tertiary amine.In summary, the discovery and development of several new variations on the Nazarov electrocyclization are described, along with synthetic applications. This work illustrates how strongly substitution patterns can impact the efficiency of the 4π-electrocyclization (Stage 1), allowing for mild Lewis acid catalysis. Over the course of these studies, we have also identified new ways to access the critical pentadienyl cation intermediates and demonstrated strategies that exploit and control the different cationic pathways available post-electrocyclization (Stage 2 processes). These advances in Nazarov chemistry were subsequently employed in the synthesis of natural product targets such as (±)-merrilactone A, (±)-rocaglamide, and (±)-enokipodin B.

Simultaneous determination of lupeol and β-sitosterol by high-performance thin-layer chromatographic method in Crataeva nurvala Buch-Ham. stem bark

Crataeva nurvala Buch-Ham. (Capparidaceae) is an important medicinal plant, the bark of which is extensively used in Ayurveda as a remedy for kidney stones, urinary tract infections, prostate-related disorders, and benign prostatic hypertrophy. In this study, a sensitive and reliable high-performance thin-layer chromatography (HPTLC) method has been developed for the simultaneous quantification of two bioactive markers, lupeol and β-sitosterol, in the stem bark of C. nurvala using precoated silica gel G 60 F254 HPTLC plates as the stationary phase and toluene–methanol (9.6:0.4, v/v) as the mobile phase. Detection and quantification were carried out by densitometric scanning at 545 nm after derivatization using 1% anisaldehyde–sulfuric acid reagent. The method was validated for linearity, inter-day and intra-day precision, repeatability, accuracy, specificity, limit of detection, and limit of quantification. The linear regression analysis data for the calibration plots showed a good linear relationship (r2 = 0.987–0.990) in the concentration range of 2 to 6 μg for lupeol and β-sitosterol, both with respect to areas. The proposed method provides good resolution of lupeol and β-sitosterol from other constituents present in the stem bark of C. nurvala. It was found to be simple, accurate, precise, and reproducible and would potentially be a useful tool for routine analysis of C. nurvala.

Effects of surface modification and organic binder type on cell performance of water-processed Ni-rich Li(Ni0.8Co0.1Mn0.1)O2 cathodes

The Ni-rich Li(Ni0.8Co0.1Mn0.1)O2 (NCM811) is surface-modified using phosphoric acid (HPO) and silane reagents, and water-based cathode slurries of unmodified and modified NCM811 are prepared with poly(acrylonitrile) (PAN) or poly(acrylic acid) (PAA) added as the binder to compare the electrochemical performances of the constructed cells. Surface modification using HPO or the addition of PAA as the binder can substantially reduce the alkalinity of the prepared aqueous slurry of NCM811, thereby preventing the slurry from corroding the aluminum current collector, as well as retaining the good structural integrity of the dried electrode. The aforementioned advantage about the reduction in the alkalinity is not achieved when the hydrophobic silane-modified NCM811 or the neutral binder PAN is used. The best cell performance in terms of electrochemical reversibility, ionic and electronic impedance, and cycle stability is obtained when the water-based cathode slurry is prepared using HPO-modified NCM811 as the cathode active and PAA as the binder simultaneously. Moreover, the addition of PAA rather than the adoption of HPO-modified NCM811 contributes more to the improvement of cell performance.

A new active NaVMoO6 cathode material for rechargeable Li ion batteries

Brannerite-type NaVMoO6 with vanadium (V5+) and molybdenum (Mo6+) elements in the highest valence states is synthesized by a sol-gel method using Na2CO3, NH4VO3, MoO3 and citric acid reagents. The results of X-ray diffraction (XRD) with Rietveld refinement and X-ray photoelectron spectroscopy (XPS) show that the obtained NaVMoO6 sample is single-phase. Novel electrode material (NaVMoO6) with layered structure is first utilized as cathode material for lithium ion batteries (LIBs). The NaVMoO6 electrode delivers reversible specific capacity of 126.4 mA h g−1 at 5 mA g−1 after 50 cycles. The stable structure of NaVMoO6 is corroborated by ex-situ XRD, suggesting that this material is considered as a prospective cathode for LIBs. This studying enriches the possibilities of molybdenum-based materials as cathodes for LIBs.