Selective Reagent Research Articles

Molecular action of larvicidal flavonoids on ecdysteroidogenic glutathione S-transferase Noppera-bo in Aedes aegypti

BackgroundMosquito control is a crucial global issue for protecting the human community from mosquito-borne diseases. There is an urgent need for the development of selective and safe reagents for mosquito control. Flavonoids, a group of chemical substances with variable phenolic structures, such as daidzein, have been suggested as potential mosquito larvicides with less risk to the environment. However, the mode of mosquito larvicidal action of flavonoids has not been elucidated.ResultsHere, we report that several flavonoids, including daidzein, inhibit the activity of glutathione S-transferase Noppera-bo (Nobo), an enzyme used for the biosynthesis of the insect steroid hormone ecdysone, in the yellow fever mosquito Aedes aegypti. The crystal structure of the Nobo protein of Ae. aegypti (AeNobo) complexed with the flavonoids and its molecular dynamics simulation revealed that Glu113 forms a hydrogen bond with the flavonoid inhibitors. Consistent with this observation, substitution of Glu113 with Ala drastically reduced the inhibitory activity of the flavonoids against AeNobo. Among the identified flavonoid-type inhibitors, desmethylglycitein (4′,6,7-trihydroxyisoflavone) exhibited the highest inhibitory activity in vitro. Moreover, the inhibitory activities of the flavonoids correlated with the larvicidal activity, as desmethylglycitein suppressed Ae. aegypti larval development more efficiently than daidzein.ConclusionOur study demonstrates the mode of action of flavonoids on the Ae. aegypti Nobo protein at the atomic, enzymatic, and organismal levels.

Improving the efficiency and environmental reliability of water supply facilities using modern reagents

This article considers methods of selection of modern reagents for treatment of industrial waste water. Based on these articles, it is proposed to replace the inefficient flocculant used in the mechanical treatment plants of one of the oil refineries with a more modern reagent. Thus, increase the efficiency and reliability of treatment facilities.

A high throughput screening model of solidophilic flotation reagents for chalcopyrite based on quantum chemistry calculations and machine learning

Flotation reagents are critical to realizing selective separation of different minerals in the flotation process. The current “trial and error” strategy for screening effective flotation reagents is time-consuming and inefficient. Herein, a combined machine learning (ML) + quantum chemistry (QC) model has been proposed to accelerate the screening of solidophilic flotation reagents. The accurate QC features of an ethyl-functional group (EFG) set involving 47 molecules have been obtained and collected as a database to describe their bonding reactions with the surface Cu(II), Fe(II), and Cu(I) ions at the B3LYP/def2-TZVP level under solvation effects. 15 QC feature descriptors and 4 ML algorithms have been adopted to establish the high throughput ML screening. QC results show the affinity of EFG molecule with Cu(II) is the strongest, followed by Fe(II), and the weakest is Cu(I). ML results show that the gradient boosting regression can successfully predict these molecules with the highest selective bonding index. The atom type, frontier molecular orbital, molecule charge, and dipole moment have significant effects on the bonding interactions. ML has shown an extremely lower time cost than the QC-based models. This work sheds new light on the development and discovery of efficient, selective, and green flotation reagents by accurate and low-cost artificial intelligence-based computational methods.

Complex study of acid-in-oil emulsions, their formation, stabilization and breakdown

Different problems may occur during acid treatment of oil reservoirs because of the incompatibility of acid with rocks and fluids. One of the issues is the formation of acid-in-oil emulsions, which block pore throats and hinder acid removal. The standard “bottle-test” method does not fully characterize such emulsions and allows only quick reagent selection. This article presents a new methodology that enables the evaluation of emulsion formation and the possible risk for acid treatment. This methodology includes visual control and measurement of viscosity, interfacial tension, and voltage stability. We found that HCl-based emulsions are generally more viscous, finer, and stable, but the high strength of the acid may lead to emulsion breakdown. We also established that emulsions that are stable under static conditions may break down after applying mechanical stress, which is a characteristic of sulfamic acid-based emulsions. Although it may not be possible to separate emulsions visually, a water content gradient may be observed in an emulsion column. Our results demonstrate that the acid and oil parameters are interconnected in emulsion formation issues. This methodology and the obtained results may be applied for quick and proper reagent selection for better acid treatment results.

An electrochemical γ-C–H arylation of amines in continuous flow

Reported here is a regioselective C(sp3)–C(sp2) cross coupling reaction between inert γ-C(sp3)–H bonds in aliphatic amines and cyanoarenes under electrochemical conditions in flow. The developed methodology takes advantage of a removable redox active auxiliary, which triggers selective 1,7-hydrogen atom transfer to functionalise an aliphatic C–H bond at the γ-position of an alkyl amine. In this reaction, a cyanoarene radical anion functions as both a selective arylating reagent and a redox active mediator, enabling the controlled one electron reduction of the redox active auxiliary. This strategy offers a new approach towards γ-C(sp3)–H bond functionalisation allowing generation of, amongst others, sterically crowded carbon centres under mild reaction conditions and in the absence of additional catalysts or radical initiators.

Progress in organocatalysis with hypervalent iodine catalysts.

Hypervalent iodine compounds as environmentally friendly and relatively inexpensive reagents have properties similar to transition metals. They are employed as alternatives to transition metal catalysts in organic synthesis as mild, nontoxic, selective and recyclable catalytic reagents. Formation of C-N, C-O, C-S, C-F and C-C bonds can be seamlessly accomplished by hypervalent iodine catalysed oxidative functionalisations. The aim of this review is to highlight recent developments in the utilisation of iodine(III) and iodine(V) catalysts in the synthesis of a wide range of organic compounds including chiral catalysts for stereoselective synthesis. Polymer-, magnetic nanoparticle- and metal organic framework-supported hypervalent iodine catalysts are also described.

Palladium-catalyzed decarboxylative O-allylation of phenols with γ-methylidene-δ-valerolactones

A novel palladium-catalyzed decarboxylative O-allylation of phenols was developed, in which a GMDV was found to be an efficient and selective allylation reagent, affording the target allyl phenyl ethers in up to 92% yields.

The Selection of Reagents for Ionic Flotation of Non-Ferrous Metals in the Series of N-Acyl-N'-Mezylhydrazines

A series of new ligands — N-acyl-N'-mesylhydrazines (MSH) — of the general formula RC(O)NHNHSO2CH3 has been obtained and considered as reagents for ionic flotation (IF) of non-ferrous metals (M(II). Reagents with a radical length of C6H13 and above form hardly soluble complexes with M(II) so it is possible to implement a kind of the ionic flotation techniques — “precipitate flotation”. The ranges of pH values of the most complete precipitation of cations from solutions have been determined. Precipitates of the metal complexes were isolated; their composition was confirmed by IR spectroscopy and elemental anal-ysis. The conditional values of the solubility product (SP) of the complexes [M(HL)2] were calculated. The dependence –lg SP = 11.8 + 0.61N is fulfilled for the MSH series and Cu(II) ions. The surface-active proper-ties of compounds with R > C6H13 were established. The reagents with optimal radical length for ionic flota-tion were selected. The ionic flotation of non-ferrous metals with N-nonanoyl-N'-mesylhydrazine was carried out. The up to 95–99 % recovery of metal ions, separation of copper and associated metal ions in diapason of pH 5–6.5 was shown to be possible.

Improved flotation of molybdenite from talc using a selective reagent scheme

Talc is one of the most problematic gangue minerals for molybdenite flotation owing to its strong natural hydrophobicity. In this work, pullulan polysaccharide (PU) was evaluated as a potential depressant in the flotation separation of molybdenite from talc. Bench flotation tests of single mineral samples and multi-mineral samples were carried out to evaluate the performance of PU in flotation. And the results show that under the preferable reagent scheme of 40 mg/L PU, 160 mg/L butyl xanthate (BX) and 25 μL/L MIBC, molybdenite can be effectively separated from talc over a wide pH range (from 2.0 to 8.0). Furthermore, FTIR and XPS analyses demonstrate that BX can desorb the pre-adsorbed PU on the surface of the molybdenite by competitive adsorption, but has only a slight effect on the PU adsorbed on surface of the talc. The results also confirm that PU has a strong and stable adsorption on the surfaces of talc and molybdenite, whereas BX adsorbs more strongly on the surface of molybdenite. Hence, the reagent scheme of PU + BX, with biodegradability, low toxicity, low cost and synergistic selectivity, has great potential for industrial application in the flotation separation of molybdenite from talc.

Spectrophotometric determination of trace amount of iron in water, food, and pharmaceutical samples

The present study aimed to determine the trace amount of iron by using highly selective and sensitive spectrophotometric reagents in water, food, and pharmaceutical samples. For this, as-triazine containing ferroin-yielding chromogens; 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine (PDT) and 3-(2-pyridyl)-5,6-bis(p-methoxyphenyl)-1,2,4-triazine (PBMPT) have been synthesized. The absorptiometric characteristics of the iron(II) complexes with PDT and PBMPT such as complex formation, sensitivity determination, composition determination have also been studied. It has been observed that these highly sensitive and selective ferroin-yielding reagents act as bidentate ligands and form intensive colored tris-complexes with iron(II) ions. The application of these spectrophotometric reagents for the determination of iron in water, food, and pharmaceutical samples has been described. Bangladesh J. Sci. Ind. Res.56(4), 299-306, 2021

An Imaging Flow Cytometry Protocol for Studying Immunoregulatory Receptor-Mediated Regulation of Phagocytosis.

Advances in flow cytometry have allowed for innovative functional investigations of innate immune cell responses. Imaging flow cytometers combine the imaging capabilities of microscopy with rapid, high-throughput data acquisition attributes of standard flow cytometers. Here, we describe a detailed method for co-expressing stimulatory and inhibitory immunoregulatory receptor-types in AD293 cells and then measuring receptor cross-talk during the regulation of the phagocytic response. Information on reagent selection, imaging flow cytometry calibration, and automated template analyses are included.

Mechanism-Based Approach to Reagent Selection for Oxidative Carbon-Hydrogen Bond Cleavage Reactions.

Numerous hydride-abstracting agents generate the same cationic intermediate, but substrate features such as intermediate cation stability, oxidation potential, and steric environment can influence reaction rates in an oxidant-dependent manner. This manuscript provides experimental data to illustrate the role that structural features play in the kinetics of hydride abstraction reactions with commonly used quinone-, oxoammonium ion-, and carbocation- based oxidants. Computational studies of the transition state structures and energies explain these results and energy decomposition analysis calculations reveal unique sensitivities to electrostatic attraction and steric repulsions. Rigorous rate studies of select reactions validated the capacity of the calculations to predict reactivity trends. Additionally, kinetics studies demonstrate the potential for product inhibition in DDQ-mediated reactions. These studies provide a clear guide to select the optimal oxidant for structurally disparate substrates and lead to predictions of reactivity that were validated experimentally.

Structural characterizations of lignins extracted under same severity using different acids

As the vital renewable feedstock originated from carbon-neutral resources, due to prominent aromaticity lignin owns the potential to produce high value-added products. Multi-functional lignin valorization demands efficient lignin extraction at milder conditions to keep its structure intact to substitute petroleum-based reactants. Lignin extraction severity (LES) is considered as the primary factor affecting the structure of extracted lignin and ultimately determines its applications. Except for the LES, the selection of suitable reagents for lignin extraction concerned with specific applications is crucially important. To explore the influence of different reagents, this study focused on lignin extraction employing the commonly used strong acids at the same LES. Four lignin preparations were extracted using 80% aqueous dioxane with the addition of H2O (L1), HCl, H2SO4 and HNO3 (pH = 1.30 ± 0.01 L2, L3 and L4, respectively). Analytical high-sensitive NMR (31P and 2D-HSQC) together with other characterizations (FTIR and GPC) were successfully employed and quantified while unveiling the structural heterogeneity among extracted lignin preparations. At the same LES, different reagents yielded lignin with varying structural characteristics and were potentially suitable for different applications.

Aryl Diazonium Salts: Powerful Arylating Agents for Catellani-Type ortho-Arylation.

The Catellani reaction provides an efficient synthetic approach to polyfunctionalized arenes. However, the selective ortho-arylating reagents employed in these reactions have been strictly limited to activated bromoarenes. As demonstrated in this work, aryl diazonium salts bearing both electron-donating and electron-withdrawing substituents, after in situ transformations with KI into the corresponding iodoarenes, were efficient arylating reagents for Catellani type ortho-arylation approaches.

Analysis of influencing factors of data error in chemical analysis of iron and steel materials

This paper analyzes the influencing factors of data error in chemical analysis of iron and steel materials, including sample preparation factor, sample decomposition factor, analytical instrument factor, reagent factor, analysis method factor. The purpose is to reduce the error of data measurement results and improve the accuracy of data analysis results by studying the measures of eliminating instrument application error, doing a good job in reagent selection, appropriately increasing the number of experiments, strictly following the operation specifications and reasonably using the allowable deviation table.

Effect of Microwave Pretreatment on Leaching of Tetrahedrite

In mineral processing, the use of microwave radiation is important especially in pre-treatment processes. At present, there is an acceleration of processes as well as an increase in the efficiency of metal recovery. One of the main problems in copper recovery from complex sulphide ores is the removal of impurities such as antimony, arsenic, mercury. In the hydrometallurgical processing scheme, the key step is the leaching. The extraction process can be influenced by the selection of suitable leaching reagents or by suitable pre-treatment of the ore. The article describes the effect of microwave radiation on the leaching Sb, As and Hg of tetrahedrite and tetrahedrite concentrate. The samples were irradiated at the power 900 W for 30 seconds. The leaching of irradiated and non-irradiated samples was realized in an alkaline sodium sulphide. The positive effect of microwave radiation was confirmed by an increase in the recovery of Sb and As already after 15 min of extraction. After microwave leaching of irradiated tetrahedrite samples, the yield of Sb was 43.2 %, in irradiated tetrahedrite concentrate, the yield of Sb was 81.3 %.

Comparison of the sensitivity of commercial aPTT tests in measurement of the pharmacodynamic response of milvexian, a novel FXIa inhibitor

Abstract Introduction The activated partial thromboplastin time (aPTT) assay is a test routinely used to evaluate abnormalities or deficiencies in coagulation factors of the intrinsic and common pathways. The composition of the surface activator and phospholipids in the aPTT reagent is known to influence the response of heparin and direct FXa or thrombin inhibitors. Milvexian (formerly referred to as BMS-986177/JNJ-70033093) is an investigational small-molecule Factor XIa (FXIa) inhibitor being studied for the prevention and treatment of major thrombotic conditions. Clinical pharmacology evaluation of milvexian includes aPTT as the primary pharmacodynamic assay, thus underscoring the need for a sensitive reagent to evaluate its anticoagulant activity. Purpose This study evaluated the sensitivity of six commercially available aPTT reagents in plasma from individual donors spiked with milvexian, at concentrations spanning the anticipated clinically relevant exposures. Methods Platelet-poor plasma (PPP) prepared from citrated whole blood collected from consenting, healthy adult volunteers (n=12) was spiked with vehicle (DMSO, 0.5% v/v) or 0.1–10 μM milvexian. The aPTT was measured using six commercially available aPTT reagent kits which included silica; kaolin, or ellagic acid as the contact activator, in combination with natural or synthetic phospholipids. The coagulation automated analysers used for testing were matched to the kit's manufacturer recommendations. All reagents and respective normal or abnormal controls were prepared as instructed by the manufacturer. Results Milvexian exhibited dose-dependent prolongation of aPTT with all reagents tested. Assays performed with aPTT reagents containing kaolin or ellagic acid demonstrated the highest sensitivity, as measured by the concentration that achieved a 2-fold aPTT prolongation (EC2x), and showed the widest dynamic range of response. Coefficient of variability of aPTT measurements in plasma from 12 individual donors was between 5.6–7.9% for Dade® Actin® FS, and 7.1–8% for STA®-C.K. Prest® 5. Conclusions Prolongation of aPTT in PPP spiked with milvexian exhibited a dose-dependent relationship, with statistically significant differences observed among reagents at milvexian concentrations above 0.3 μM. The highest sensitivity measured by changes in the ratio to baseline was obtained with aPTT reagents containing an activator/procoagulant phospholipid combination of ellagic acid + purified soy phosphatides or kaolin + cephalin, which performed similarly. Identification of the reagents with the best combination of sensitivity, precision, and dynamic range may help guide the selection of reagent for assessing milvexian activity. Funding Acknowledgement Type of funding sources: Private company. Main funding source(s): Janssen Research & Development, LLC

EXTRACTION OF PALLADIUM

It is known that a series of organic compounds containing in molecule SH-, NH- qroups, including halogens, carboxylic acids and their derivatives, have the ability to form the innercomplex compounds under certain conditions. These compounds permit to carry out the extraction in acidic medium, that prevents the of process hydrolysis. They are not dissolved in water but are soluble in various solvents and form colored solutions and so may be used as an extractants. The main purpose of this paper is the study of palladium extraction ability for chlorinated naphthenic acids (CNA) synthesited in laboratory on the basis of industrial alkylphenols. Ammoniumacetate with various pH was used as a buffer to extract palladium from PdCl2·2H2O 0.1 mkg/ml solution. The main task for the use of inert organic compound in extraction is the selection of reagent which dissolves it but does not form any compound. With this aim the influence of different solvents on their reagent was researched. The experiments show that chloronaphthenic acid is dissolved well in organic solvents. Its solution, for example in kerosene, is light-resistant, does not hydrolyze in water, alkalis and acids. So, chloronaphthenic recomendefor palladium extraction

Evaluation of the Humoral Response to Adeno-Associated Virus-Based Gene Therapy Modalities Using Total Antibody Assays.

The number of viral vector-based gene therapies (GTx) continues to grow with two products (Zolgensma® and Luxturna®) approved in the USA as of March 2021. To date, the most commonly used vectors are adeno-associated virus-based (AAV). The pre-existing humoral immunity against AAV (anti-AAV antibodies) has been well described and is expected as a consequence of prior AAV exposure. Anti-AAV antibodies may present an immune barrier to successful AAV transduction and hence negatively impact clinical efficacy and may also result in adverse events (AEs) due to the formation of large immune complexes. Patients may be screened for the presence of anti-AAV antibodies, including neutralizing (NAb) and total binding antibodies (TAb) prior to treatment with the GTx. Recommendations for the development and validation of anti-AAV NAb detection methods have been presented elsewhere. This manuscript covers considerations related to anti-AAV TAb-detecting protocols, including the advantages of the use of TAb methods, selection of assay controls and reagents, and parameters critical to monitoring assay performance. This manuscript was authored by a group of scientists involved in GTx development representing eleven organizations. It is our intent to provide recommendations and guidance to industry sponsors, academic laboratories, and regulatory agencies working on AAV-based GTx viral vector modalities with the goal of achieving a more consistent approach to anti-AAV TAb assessment. Graphical abstract

A new green method for indirect determination of ferric ions in biological samples using Ascorbic acid as reducing agent via the development of CFIA system

A simple, sensitive, automated and environmentally friendly FI/MZ technique was suggested for the indirect determination of iron (III) as ferric chloride in bulk and biological. These method involve the reduction of Fe (III) to Fe (II) using ascorbic acid as reducing agent, the reduced ion was reacted with 1,10- phenanthroline as a selective organic reagent to form red-orange complex, measured at λ=510 nm. The complexation ratio between matel ion with ligand was 1:3 ratio (M: L). The colored product obeyed Beer’s Law with linear ranges 1-30 and 8-75 μg/mL with detection limits 1.02, 0.28 μg/mL for batch and FIA/MZ methods, respectively. The rate of sampling was 54 sample/h, the %RSD less than 2% and the recovery was about 99%. The developed technique was simply and low cost with high throughput, it provides the use of an aqueous medium as carrier of chemicals in flow system that is nontoxic and causes no pollution, thereby belonging to green chemistry. The proposed procedure can be successfully applied to estimate the content of Iron (III) in biological samples. The results of estimation are satisfactory as compared with those given by a reference method, showed the new method to be accurate and precise at the 95% confidence level.