Types Of Reagents Research Articles

Electron ionization induced fragmentation of fluorinated derivatives of bisphenols.

Fluorinated derivatization agents allow for the identification and quantification of emerging pollutants with high sensitivity, yet details of their potential applications using electron ionization are lacking. The fluorine atom itself does not effectively participate in electron ionization. Furthermore, limited information exists regarding the effect of fluorine during electron ionization-induced fragmentation. To fill this gap, this report presents the fragmentation pathways of the fluorinated derivatives of ten bisphenol analogues as exemplary emerging pollutants. The bisphenols were derivatized by the acetylation reagent trifluoroacetic anhydride and a new silylation reagent, namely dimethyl(3,3,3-trifluoropropyl)silyldiethylamine (DIMETRIS; previously applied for the analysis of selected pharmaceuticals in environmental samples), and analyzed using GC/MS (electron ionization, 70 eV). Deuterated bisphenol A was added to the group of analytes to confirm the proposed fragmentation pathways. The specific chemical structure of bisphenols gives the possibility of several resonance hybrids of C-centered radicals. This, in turn, results in several fragmentation pathways, unique for each resonance hybrid. Sequential losses of radicals and neutral fragments were observed in both types of derivative, with final stable carbenium ions. McLafferty-type rearrangements were observed between the native structure of the analytes and the introduced substituents. The gamma-shift of F onto Si in the Si(CH2 )2 CF3 substituent is proposed to explain the loss of the fragment with a mass of 78 u. Both types of derivatization reagent used were found to be applicable, although the use of DIMETRIS was limited for high-mass bisphenols. The introduction of fluorine by derivatization brings benefits for the qualitative and quantitative analysis of bisphenol-type compounds using GC/MS because of the presence of characteristic ions in the mass spectra.

Monoclonal antibody specific to the Dia blood group antigen generated by phage display technology.

Alloanti-Dia can be implicated in mild to severe blood transfusion reactions. Given the concomitance of a high prevalence of the Dia antigen and antibody circulating in some populations, an anti-Dia typing reagent is required in order to enable safe blood transfusions. Limitations of hybridoma technology to produce such a reagent led to the use of phage display technology to generate an anti-Dia monoclonal antibody. A library of phages displaying murine single-chain variable fragment antibody (scFv-phages) was consecutively adsorbed with different panels of Di(a-b+) red cells to eliminate scFc-phages that potentially bind irrelevant blood group antigens. Thereafter, the subtractive library was specifically selected for the scFv-phages that bound Dia antigen by sequentially biopanning the library with Di(a+b+) cell ghosts and Di(a+b-) intact red cells. A specific interaction between the selected scFv-phages and Dia epitope was validated with the Dia peptide by a competitive haemagglutination inhibition assay and confirmed with the red cells by flow cytometry. An scFv-phage clone specifically bound the Dia epitope, as shown by its binding competition with the human anti-Dia to the Dia peptide in a haemagglutination inhibition test. Moreover, it was highly reactive to Di(a+b+) red cells but not to Di(a-b+) red cells, as determined by flow cytometry. In this study, a Dia-specific scFv-phage antibody was successfully produced. The selection protocol might be a prototypic platform for producing monoclonal antibodies to relevant blood group antigens. The scFv-phage produced in this way warrants further development for use as a reagent for Dia red cell typing.

The effect of reagent type on generating bulk sub-micron (nano) bubbles and flotation kinetics of coarse-sized quartz particles

Dodecylamine (DDA) is a commonly used collector in the froth flotation of quartz particles. The present work for the first time studies the effect of DDA nanobubbles (NBs) on the flotation of coarse particles (−425 + 300 μm, −300 + 212 μm and − 212 + 106 μm). For this purpose, 50 mg/l DDA was employed as a primary material for producing bulk NBs via hydrodynamic cavitation technique to be used in the flotation kinetics tests. For comparative purposes, pine oil (PO), Methyl Isobutyl Carbinol (MIBC) and polypropylene glycol (A65) with a concentration of 22.4 mg/l were utilized for generating NBs and also as a frother. According to the results, generated NBs categorized based on the stability and mean bubble size as DDA > PO > MIBC>A65. The flotation rate constants (k) and ultimate recoveries (Rmax) obtained in the presence of the DDA-NBs were substantially improved compared to the corresponding values given for the frother types NBs. That was mainly related to the chemical functionality of the agent together with its extended stability. The experimental results showed a Rmax of 97.5% using the DDA-NBs in the condition of without any frother; however, the highest recovery using common air bubbles (CBs) was obtained 90.8% by the PO. Additionally, the influential order of the three frothers and the DDA on flotation rate constant was shown as DDA > PO > MIBC>A65 for each fraction size. Finally, the results indicated that the k and Rmax of coarse particles were improved by 22% and 21% in the presence of the DDA-NBs.

The use of release analysis to show the selectivity of reagents towards differently sized feeds of the same coal

ABSTRACT Release analysis is used to characterize the cleaning ability of coal fines. It defines the limit of separation at any target level of ash. Since flotation depends upon many factors like feed size and its composition, surface properties, and type of reagents, it is important to characterize the optimum boundary of separation. Release analysis following the BS7503 procedure was used to characterize a − 0.5 mm composite feed and three sized feeds, i.e., −0.5 + 0.25, −0.25 + 0.1, and −0.1 mm using different reagent combinations. Coal response reflected by release curves and corresponding batch flotation results for various reagent combinations was found to be different for all three feeds. No single combination of collector and frother could deliver the maximum separation over the entire clean coal ash range for all three feeds. Significant yields ranging from 35% to 86% could be obtained at the 13% to 17% ash level for the medium volatile metallurgical coal investigated. Release curves and subsequent batch flotation results were found to be sensitive to feed size, feed size distribution, and reagent combination types with their corresponding dosage indicating that the clean coal ash requirement would dictate the application of reagents. The investigation results further show that release analysis results can be reproduced by batch flotation.

Comparative analysis of the results of vanadium chemical extraction out of Ural titanium-magnetite ore tails and concentrate

Demand for vanadium significantly exceeds supply at the world market, determining the relevance of research on the involvement of various raw materials and technological processes to increase its production. The research was carried out to increase the efficiency of the vanadium extraction process out of titanium-magnetite ore concentrate and titanium-magnetite ore enrichment tails. For the study, samples of Ural titanium-magnetite ore tails and concentrate with different chemical compositions were used. The effect of roasting temperature, the amount and type of reagents for roasting and leaching on the vanadium extraction degree was studied. Na 2 CO 3 or NaCl were used as reaction additives to the charge for roasting of tails, and Na 2 CO 3 was used for roasting of concentrate samples. The content of the reagent Na 2 CO 3 or NaCl varied and amounted to 23, 33, 40 and 50% of the charge mass. Oxidative roasting was carried out at temperatures of 700, 850 and 950°C. It was shown that an increase of the Na 2 CO 3 content in the charge with the concentrate from 23 to 40%, results in increasing of the degree of vanadium extraction from 36 to 54%. An increase in the NaCl content from 23 to 40% in the charge with tails results in increasing of the vanadium extraction degree from 32 to 46%, and at NaCl content 50%, the vanadium extraction degree increased to 64%. An increase in the roasting temperature of the charge from 700 to 950°C led to an increase in the vanadium extraction degree to 71-83.1% in different ore samples. Chemical extraction of vanadium out of unroasted concentrate samples was carried out by leaching with hydrochloric acid HCl. An increase in the concentration of HCl from 10 to 30% led to an increase in the vanadium extraction degree from 15 to 44%.

Dedicated to a peptide chemist of few words and immense impact: Louis A. Carpino

Dedicated to a peptide chemist of few words and immense impact: Louis A. Carpino

Adsorption of heavy metal and organic pollutant by organo-montmorillonites in binary-component system

In this study, the adsorption capacity of organo-montmorillonites (OMt) modified with cationic surfactants and chelating reagent toward binary-component, heavy metal and organic pollutant, in aqueous solution was investigated through batch experiments. The characteristics of the OMt were analyzed by X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), Specific surface area (BET), respectively, confirming that hexadecyl trimethyl ammonium chloride (CTAC), ethylene diamine tetraacetic acid (EDTA) and 1,6-diaminohexane (DA) were successfully introduced into Na+-Mt. Comparing with stronger Zn2+ removal efficiency onto EDTA-Mt and DA-Mt dominated by forming complexes in the binary-component systems, CTAC–EDTA-Mt and CTAC–DA-Mt gained a huge edge in uptaking phenol controlled by layer partition. Factors containing the initial Zn2+/phenol concentration and the competitive adsorption where the Zn2+, Pb2+, Cd2+ and phenol/Zn2+, p-nitrophenol, phenylamine and phenol coexisted in the aqueous solution were shown in the paper. Furthermore, the desorption of Zn2+ and phenol on the CTAC–DA-Mt was investigated by series experiments under various conditions (with the type of chemical reagents, variable concentration of desorbent and contact time). The results showed HCl solution had higher efficiency on desorbing Zn2+ over phenol onto the CTAC–DA-Mt. CTAC–EDTA-Mt and CTAC–DA-Mt had potential applications in dealing with the wastewater where heavy metals and organic pollutants coexist.

Synthesis and Hydrosilylation of Vinyl-Substituted Open-Cage Silsesquioxanes with Phenylsilanes: Regioselective Synthesis of Trifunctional Silsesquioxanes

Herein, we report an efficient synthesis and functionalization of trifunctional open-cage-type silsesquioxanes. The method proposed has been successfully applied for the synthesis of a library of incompletely condensed silsesquioxanes with vinyldiorganosilyl functional groups, which allows further modification. Detailed studies of hydrosilylation of sterically different open-cage vinylsilsesquioxanes with a wide spectrum of phenylsilanes catalyzed by platinum and rhodium compounds are also reported. The influence of the reaction parameters, types of reagents, and catalysts employed on the efficiency of the process was examined. Optimization of the process based on the above results permitted the design of a very attractive method for the synthesis of multifunctionalized silsesquioxanes with excellent yields and regioselectivity. Moreover, the results allowed the choice of the most efficient catalyst whose application led to the selective formation of substituted open-cage silsesquioxanes. These new compounds have been fully characterized and studied in terms of their thermal properties.

Synthetic Studies towards CH‐Diazomethane Sulfonamides: a Novel Type of Diazo Reagents

Preparation of CH‐diazomethane sulfonamides has been developed for the first time. Their utility as a new type of diazo reagents was showcased in cycloaddition reactions with electron‐deficient alkynes and β‐nitro styrenes which delivered medicinally important pyrazole‐3‐sulfonamides in good to excellent yields.

Removal of picloram herbicide from an aqueous environment using polymer inclusion membranes

Abstract The picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid) herbicide is widely applied to control the growth of woody plants and it has been frequently detected in aqueous environments due to its poor adsorption by soils and high leaching potential. Consequently, the removal of picloram from contaminated environmental waters is of major concern due to its adverse impacts on aquatic organisms, soils and animals. The development of a method for the extraction and transport of picloram from aqueous solutions using a polymer inclusion membrane (PIM) composed of cellulose triacetate, trioctylmethylammonium chloride (Aliquat 336) and 2–nitrophenyl octyl ether (NPOE) is reported. The experimental method was optimized for the PIM composition, and the type and concentration of stripping reagent. The optimized method demonstrated good performance indicators of flux and transport efficiency for picloram during non-competitive and competitive transport experiments. The PIM was also successfully applied in a passive sampling device to recover picloram at the maximum permissable concentration of 500 μg/L from a complex matrix of natural water. Findings from this study demonstrate that PIMs can serve as a potential alternative method for the removal and recovery of picloram and related herbicides from contaminated aqueous solutions.

An Autonomous Chemical Robot Discovers the Rules of Inorganic Coordination Chemistry without Prior Knowledge

AbstractWe present a chemical discovery robot for the efficient and reliable discovery of supramolecular architectures through the exploration of a huge reaction space exceeding ten billion combinations. The system was designed to search for areas of reactivity found through autonomous selection of the reagent types, amounts, and reaction conditions aiming for combinations that are reactive. The process consists of two parts where reagents are mixed together, choosing from one type of aldehyde, one amine and one azide (from a possible family of two amines, two aldehydes and four azides) with different volumes, ratios, reaction times, and temperatures, whereby the reagents are passed through a copper coil reactor. Next, either cobalt or iron is added, again from a large number of possible quantities. The reactivity was determined by evaluating differences in pH, UV‐Vis, and mass spectra before and after the search was started. The algorithm was focused on the exploration of interesting regions, as defined by the outputs from the sensors, and this led to the discovery of a range of 1‐benzyl‐(1,2,3‐triazol‐4‐yl)‐N‐alkyl‐(2‐pyridinemethanimine) ligands and new complexes: [Fe(L1)2](ClO4)2 (1); [Fe(L2)2](ClO4)2 (2); [Co2(L3)2](ClO4)4 (3); [Fe2(L3)2](ClO4)4 (4), which were crystallised and their structure confirmed by single‐crystal X‐ray diffraction determination, as well as a range of new supramolecular clusters discovered in solution using high‐resolution mass spectrometry.

An Autonomous Chemical Robot Discovers the Rules of Inorganic Coordination Chemistry without Prior Knowledge.

We present a chemical discovery robot for the efficient and reliable discovery of supramolecular architectures through the exploration of a huge reaction space exceeding ten billion combinations. The system was designed to search for areas of reactivity found through autonomous selection of the reagent types, amounts, and reaction conditions aiming for combinations that are reactive. The process consists of two parts where reagents are mixed together, choosing from one type of aldehyde, one amine and one azide (from a possible family of two amines, two aldehydes and four azides) with different volumes, ratios, reaction times, and temperatures, whereby the reagents are passed through a copper coil reactor. Next, either cobalt or iron is added, again from a large number of possible quantities. The reactivity was determined by evaluating differences in pH, UV‐Vis, and mass spectra before and after the search was started. The algorithm was focused on the exploration of interesting regions, as defined by the outputs from the sensors, and this led to the discovery of a range of 1‐benzyl‐(1,2,3‐triazol‐4‐yl)‐N‐alkyl‐(2‐pyridinemethanimine) ligands and new complexes: [Fe(L1)2](ClO4)2 (1); [Fe(L2)2](ClO4)2 (2); [Co2(L3)2](ClO4)4 (3); [Fe2(L3)2](ClO4)4 (4), which were crystallised and their structure confirmed by single‐crystal X‐ray diffraction determination, as well as a range of new supramolecular clusters discovered in solution using high‐resolution mass spectrometry.

Towards clean HSMG® graphene transfer

Large area graphene has been studied for several years now. In order to get most of its outstanding properties, graphene has to been free of imperfections and contamination that are usually introduced in the growth and transfer process. In this work High Strength Metallurgical Graphene transfer process is investigated. Study is focused on the wet transfer method using different types of etching reagents and their influence on graphene layer. The samples are tested using several research technics identifying impurities, morphology, resistance, etc. The study of polymer matrix removal with different types of organic solvents and thermal annealing is conducted as well. Additionally, the influence of storage conditions is investigated.

Palladium-mediated Suzuki-Miyaura Cross-Coupling Reaction of Potassium Boc-protected aminomethyltrifluoroborate with DNA-Conjugated aryl bromides for DNA-Encoded chemical library synthesis

A mild reaction for DNA-compatible, palladium promoted Suzuki-Miyaura cross-coupling reaction of potassium Boc-protected aminomethyltrifluoroborate with DNA-conjugated aryl bromides has been developed efficiently. This novel DNA encoded chemistry reaction proceeded well with a wide range of functional group tolerance, including aryl bromides and heteroaryl bromides. Further, the utility our DNA conjugated aminomethylated arene products is demonstrated by reaction with various types of reagents (including amide formation with carboxylic acids, alkylation with aldehydes, and carbamoylation with amines) as would be desired for the production of a DNA encoded library.

Bromo-spiroisoxazoline Alkaloids, Including an Isoserine Peptide, from the Caribbean Marine Sponge Aplysina lacunosa.

Three new bromotyrosine spiroisoxazoline alkaloids, lacunosins A and B (1 and 2) and desaminopurealin (3), were isolated from a MeOH extract of the marine sponge Aplysina lacunosa that showed modest α-chymotrypsin inhibitory activity. The structures of 1-3 share the spirocyclohexadienyl-isoxazoline ring system found in purealidin-R and several other Verongid sponge secondary metabolites. Compounds 1 and 2 are coupled to a glycine and an isoserine methyl ester, respectively. Alkaloid 3 is linked, contiguously, to an O-1-aminopropyl 3,5-dibromotyrosyl ether and, finally, to histamine through an amide bond. The planar structures of all three compounds were obtained from analysis of MS and 1D and 2D NMR data. The absolute configuration of the SIO unit of 1-3 was assigned by electronic circular dichroism (ECD). The isoserine amino acid residue in 2 was found to be a 1:1 mixture of epimers using a new Marfey's type reagent, derived from Trp-NH2. Allylic O-naphthoylation of the SIO subunit enhances the ECD spectrum of SIOs and improves discrimination of enantiomorphs. A unifying hypothesis is proposed that links the biosynthesis of several of the new compounds with previously reported analogues.

Science in the fight against the novel coronavirus disease 2019 (COVID-19).

Science in the fight against the novel coronavirus disease 2019 (COVID-19).

Sensitive determination of hydrogen peroxide in real water samples by high spin peroxo complex.

In this paper, a fast, cheap, simple, sensitive and selective spectrophotometric method based on high spin peroxo-Fe(III)-EDTA complex in the alkaline medium was developed for the determination of hydrogen peroxide (H2O2) in real water samples. The purple-coloured complex with a maximum absorbance at a wavelength of 525 nm was formed. Various parameters such as type of stabilizer reagent and its concentration, reaction time, Fe(III), EDTA and NH3 concentration were optimized. The method was confirmed with the Beer’s law with a molar absorption coefficient of 267.36 L mol-1 cm-1 in the 8.3 ×10-6 –4.08 ×10-3 mol/L concentration range. Sandell’s sensitivity of the proposed method was also calculated as 0.188 μg/cm2 . LOD and LOQ were determined as 2.5 ×10-6 and 8.3 ×10-6 mol/L, respectively. Intraday and interday relative standard deviation of the proposed method for 2.0 ×10-4 mol / L of H2O2 were found as 1.5% and 6.1%, respectively. The developed method is suitable for fast monitoring of H2O2 in different types of aqueous water samples without any sample preparation steps and acceptable recovery values between 90% and 118% were obtained. In the sample analysis, H2O2 removed solutions from the real water samples were used for blank correction in their analysis and this process provides more reliable and accurate results in real sample analysis.

Red cell genotyping in Thailand: trends for blood transfusion in Asian populations

Numerous molecular techniques have been employed to determine well‐matched blood units for patients in need, particularly those requiring blood transfusions within 3 months and presenting positive DAT results. Only specialized reference laboratories use commercially available kits for red cell (RC) genotyping due to their expense and requiring extremely sophisticated instruments. Moreover, regarding complicated cases, particular typing reagents may be unavailable or insufficient. Therefore, identifying and confirming the compatibility of the blood units donated would require more time. This article aims to review the present uses of RC genotyping in Thailand and their significant contributions to transfusion practices in Asian populations. RC genotyping using PCR‐sequence‐specific primer (PCR‐SSP) and multiplex PCR (M‐PCR) has been established and used in patient and donor populations. The results of genotyping acquired by PCR‐SSP and M‐PCR were precise and in agreement with serological techniques. Predicted phenotypes of clinically significant blood group systems have been used to determine the compatibility of RC units among Thai patients having multiple antibodies. As a result, one additional advantage is the expanded storing of donated, frozen rare blood types. RC genotyping for high‐ and low‐prevalence antigens among differing Asian ethnicities requires consideration. RC genotyping employing these advanced PCR techniques could provide testing results that are both reliable and appropriate to screen suitable donor blood units in complex cases or patients presenting rare blood types. In addition, comparable strategies could be employed in other Asian populations using limited resources.

The Behavior of Gangue During the Flotation of a Sulfidic PGM-Bearing Ore in Response to Various Monovalent and Divalent Ions in Process Water.

Mineral concentrators are becoming increasingly aware of the importance of the quality of the water that they feed into their milling and flotation circuits. It is speculated that different inorganic constituents of process water may yield different flotation results owing to the electrolyte–reagent–mineral interactions occurring in the pulp phase. These interactions are said to be specific to ion type, reagent type, and mineral or ore type. It therefore stands to reason that there is a need to develop an understanding of the specific ion effects on both the pulp phase and the froth phase phenomena, such that the chemistry and the quality of process water can be monitored and controlled in a manner that does not negatively affect the flotation performance. Previous research has shown that inorganic electrolytes may impact the hydrophobicity and the floatability of mineral particles and could in turn affect froth stability, entrainment, and thus mineral grades and recoveries. In this study, the floatability of a Cu-Ni-PGM-bearing Merensky ore is tested on a bench-scale flotation system in various single salt solutions, viz., CaCl2, CaSO4, Ca(NO3)2, MgCl2, Mg(NO3)2, MgSO4, NaCl, NaNO3, and Na2SO4, in order to examine specific ion effects on gangue recovery. Coagulation and zeta potential tests are conducted in order to establish the nature of the impact that specific ions have on the behavior of gangue in flotation. The findings of this work have shown that single salt solutions containing ions resulted in a strong depression of gangue compared to those solutions containing Cl− and SO42− ions. It was also shown that the divalent Ca2+ and Mg2+ showed a stronger depression of gangue compared to the monovalent Na+. Ca2+, in comparison to Na+, resulted in an increase in the coagulation of the ore as well as an increase in the zeta potential of talc. Overall, the findings of this paper suggest that the presence of Ca2+ and Mg2+ in process water would most likely create conditions that promote gangue depression.

Screening a chemically defined extracellular matrix mimetic substrate library to identify substrates that enhance substrate-mediated transfection.

Nonviral gene delivery, though limited by inefficiency, has extensive utility in cell therapy, tissue engineering, and diagnostics. Substrate-mediated gene delivery (SMD) increases efficiency and allows transfection at a cell-biomaterial interface, by immobilizing and concentrating nucleic acid complexes on a surface. Efficient SMD generally requires substrates to be coated with serum or other protein coatings to mediate nucleic acid complex immobilization, as well as cell adhesion and growth; however, this strategy limits reproducibility and may be difficult to translate for clinical applications. As an alternative, we screened a chemically defined combinatorial library of 20 different extracellular matrix mimetic substrates containing combinations of (1) different sulfated polysaccharides that are essential extracellular matrix glycosaminoglycans (GAGs), with (2) mimetic peptides derived from adhesion proteins, growth factors, and cell-penetrating domains, for use as SMD coatings. We identified optimal substrates for DNA lipoplex and polyplex SMD transfection of fibroblasts and human mesenchymal stem cells. Optimal extracellular matrix mimetic substrates varied between cell type, donor source, and transfection reagent, but typically contained Heparin GAG and an adhesion peptide. Multiple substrates significantly increased transgene expression (i.e. 2- to 20-fold) over standard protein coatings. Considering previous research of similar ligands, we hypothesize extracellular matrix mimetic substrates modulate cell adhesion, proliferation, and survival, as well as plasmid internalization and trafficking. Our results demonstrate the utility of screening combinatorial extracellular matrix mimetic substrates for optimal SMD transfection towards application- and patient-specific technologies.Impact statementSubstrate-mediated gene delivery (SMD) approaches have potential for modification of cells in applications where a cell-material interface exists. Conventional SMD uses ill-defined serum or protein coatings to facilitate immobilization of nucleic acid complexes, cell attachment, and subsequent transfection, which limits reproducibility and clinical utility. As an alternative, we screened a defined library of extracellular matrix mimetic substrates containing combinations of different glycosaminoglycans and bioactive peptides to identify optimal substrates for SMD transfection of fibroblasts and human mesenchymal stem cells. This strategy could be utilized to develop substrates for specific SMD applications in which variability exists between different cell types and patient samples.