Two-step Reaction Research Articles

Phytochemical screening, gas chromatograph/mass spectrometer (GCMS) analysis and molecular toxicological potential of Hunteria umbellata aqueous fruit extract against Staphylococcus aureus in accessory gene regulators (AGRs)

BackgroundFruits of Hunteria umbellata (HU) have been utilized in folk medicine as potent against Staphylococcus aureus (SA) infections, particularly skin and nasal related conditions. However, there is scarcity of literature concerning toxicological evaluation of graded doses of HU fruit, especially at molecular level, specifically targeting the accessory gene regulator (AGR) system to prevent abuse of doses in the treatment of bacterial infections. This research evaluated molecular toxicological property of SA exposed to varied concentrations of aqueous HU fruit extract ranging from 500 to 3.90625 µg/µL using broth microdilution method and quantification of AGR I and II genes’ expression employing two-step reverse transcriptase quantitative polymerase chain reaction (RT-qPCR). We first identified quality and quantity of chemical compounds in aqueous fruit of HU using phytochemistry and hybrid gas chromatograph–mass spectrometer (GC–MS) technique. Additionally, preliminary bactericidal potential of HU was assessed before molecular toxicology.ResultsResults revealed six phytochemicals and twenty analytical grade compounds from a standard library were identified from chromatograms of HU fruit extract. Some main compounds detected are n-Hexadecanoic acid (25.24%), 2-Pentadecanone, 6,10,14-trimethyl (16.08%), Cuparene (16.63%), Tetradecanoic acid (6.21%) and 9-Octadecenoic acid, (E)- (5.70%). Bactericidal activity shows significant (p < 0.05) toxicity in the tested (8) concentrations of HU fruits in a dose-response relationship compared to the controls (positive and negative). The quantified expression of AGR I and II genes in SA was most significantly increased (p < 0.05) at both 250 and 500 µg/µL of HU fruit extract while least significant increase (p < 0.05) was recorded at 125 µg/µL compared to control.ConclusionsNotably, the study highlighted a potential risk of augmented bacterial infection especially with higher doses of HU extracts during boils’ treatment and other epidermal infections instigated by Staph. Expression of both AGR genes at higher doses (250 and 500 µg/µL) is indicative of further expression of several other genes responsible for virulence factors in a variety of human bacterial infections. Thus, consumption of HU fruit to treat boils and blisters should be with great caution especially at high doses.

Thermal dissipation of two-step combustible tangent hyperbolic fluid with quadratic Boussinesq approximation and convective cooling

This study explores thermal criticality and dissipation involving a two-step reaction in a hyperbolic tangential fluid flow and quadratic Boussinesq approximation to model the complex internal heat transfer mechanisms during combustion. Subject to suitable convective boundary conditions, the transformed energy and momentum equations are numerically solved using Galerkin approximation integration coupled with a weighted residual scheme. The outcomes are disseminated using a variety of graphs to illustrate for parametric sensitivities of the thermal and velocity profiles. Based on the results, it is discovered that increases in the Frank-Kamenetskii parameter, Brinkman number, Weissenberg number, activation energy, activation ratio term, and second step term all aid in the complete combustion of hydrocarbons. Monitoring all terms that stimulate internal heat generation is essential to avoid system blow-ups.

Catalytic hydrogenolysis of polypropylene and polyethylene mixtures: Effect of temperature on liquid alkane components

This study explored the interactions between different polyolefins using a commercial Ru/C catalyst-mediated hydrogenolysis of polypropylene (PP), low-density polyethylene (LDPE), and their mixtures. The effects of the mass ratio of polyolefins to the catalyst, temperature, pressure and time on the yield of products and the internal components of liquid alkane products were studied, and the optimum conditions for solo plastic hydrogenolysis were determined. The highest liquid alkane yields of PP (46.70 %) and LDPE (70.70 %) were obtained at 250 and 210 °C, respectively. Further, the interactions between PP and LDPE during co-hydrogenolysis were observed. The temperature had a significant influence on the gaseous and liquid products, and we proposed a two-step hydrogenolysis reaction process for a mixture of polyethylene with polypropylene conducted at various temperatures. Co-hydrogenolysis provides a high-value utilization path for polyolefins that are difficult to separate during recovery.

Thermal Decomposition and Combustion Analysis of Malaysian Peat Soil Samples Using Coats Redfern Model-free Method

This research investigates the thermal decomposition behaviour of Malaysian peat soil through thermogravimetric analysis at varying heating rates. The study aims to analyse the thermal kinetics of decomposition for distinct peat soil types under inert and oxidative atmospheres while considering the role of available oxygen. The investigation encompasses virgin and agricultural peat, employing a non-isothermal thermogravimetric analysis technique to evaluate thermal decomposition characteristics and compute kinetic parameters using the Coats Redfern model-free approach. The pyrolysis profiles reveal three primary stages: moisture evaporation (30–180°C), organic component decomposition (200–500°C), and mineral decomposition (600–800°C). Virgin peat experiences a 43% mass loss during pyrolysis, while agricultural peat shows a 46% mass loss, emphasising insights into thermal behaviour and consistent decomposition patterns across peat types. Combustion profiles exhibit three main stages: dehydration (30–180°C), oxidative pyrolysis transforming organic matter into volatiles and char (200–300°C), and subsequent char oxidation (300–500°C). The study determines average activation energy trends, measuring 14.87 kJ/mol for virgin peat and 5.37 kJ/mol for agricultural peat under an inert atmosphere, and 28.89 kJ/mol for virgin peat and 36.66 kJ/mol for agricultural peat under an oxidative atmosphere. The research introduces an innovative two-step reaction model elucidating peat thermal decomposition kinetics (excluding dehydration), including a discussion on the impact of oxygen availability on kinetic parameters. These findings essential peat fire smouldering modelling, contributing to peat combustion behaviour for effective strategies to reduce peat fire risks.

Cloning, Expression, and Functional Characterization of Two Highly Efficient Flavonoid-di-O-glycosyltransferases ZmUGT84A1 and ZmUGT84A2 from Maize (Zea mays L.).

The maize (Zea mays L.) glycosyltransferase family 1 comprises many uridine diphosphate glycosyltransferase (UGT) members. However, UGT activities and biochemical functions have seldom been revealed. In this study, the genes of two flavonoid di-O-glycosyltransferases ZmUGT84A1 and ZmUGT84A2 were cloned from maize plant and expressed in Escherichia coli. Phylogenetic analysis showed that the two enzymes were homologous to AtUGT84A1 and AtUGT84A3. The two recombinant enzymes showed a high conversion rate of luteolin to its glucosides, mainly 4',7-di-O-glucoside and minorly 3',7-di-O-glucoside in two-step glycosylation reactions in vitro. Moreover, the recombinant ZmUGT84A1 and ZmUGT84A2 had a broad substrate spectrum, converting eriodictyol, naringenin, apigenin, quercetin, and kaempferol to monoglucosides and diglucosides. The highly efficient ZmUGT84A1 and ZmUGT84A2 may be used as a tool for the effective synthesis of various flavonoid O-glycosides and as markers for crop breeding to increase O-glycosyl flavonoid content in food.

Cu, Co co-doped Ni3S2 nanosheets grown on nickel foam as an efficient catalyst for urea oxidation reaction

Doping modification can significantly enhance the catalytic performance of Ni3S2 in urea oxidation reaction (UOR). In this study, we synthesized Cu, Co co-doped Ni3S2 nanosheets on nickel foam (Cu/Co-Ni3S2/NF) through a two-step hydrothermal reaction. Cu, Co dual-doped Ni3S2 nanosheets exhibited a thickness of about 30 nm, composed of nanoparticles. Benefiting from the synergistic regulation of Cu and Co dopants on electronic structure, increased availability of active sites, boosted electron transference rates, and improved electrical conductivity, Cu/Co-Ni3S2/NF exhibited an excellent UOR catalytic performance and enhanced reaction kinetics, offering a low potential of 1.350 V at 100 mA cm-2, along with a low Tafel slope of 15.5 mV dec-1. Moreover, Cu/Co-Ni3S2/NF coupled with Pt/C/NF only necessitated 1.68 V to drive 100 mA cm-2 for overall urea splitting, which is lower than that of traditional water splitting (1.996 V). This indicates that the addition of urea into electrolyte is an energy-conserving strategy for hydrogen production from water electrolysis. This work provides a novel dual-ion doping method to design a highly efficient electrocatalysts for UOR.

New Strategy for the Synthesis of Some Valuable Chiral 1,3-Diols with High Enantiomeric Purity: New Organocatalyst, Asymmetric Aldol Reaction, and Reduction.

Chiral 1,3-diols are highly valuable molecules used in industries such as pharmaceuticals, cosmetics, and agriculture. Therefore, in this study, a new strategy was developed to synthesize enantiomerically pure (>99% ee) 1,3-diols. New chiral 1,3-diols (5a-5q) with high enantiomeric purity were synthesized from aldol products chiral 1,3-keto alcohols (4a-4q), which are aldol products with different structures. Chiral 1,3-keto alcohols (4a-4q) were synthesized by a new asymmetric aldol method in the first step. This method was developed using a new proline-derived organocatalyst (3g) and Cu(OTf)2 as an additive in DMSO-H2O for the first time. Almost >99% ee was obtained using our developed aldol procedure. In the second step, original chiral diols (5a-5q) of high enantiomeric purity were obtained by asymmetric reduction of chiral keto alcohols with chiral oxazaborolidine reagents. In this way, a two-step asymmetric reaction was developed for chiral 1,3-diol enantiomers with high enantiomeric purity. The structures of all the original chiral compounds obtained were elucidated by infrared and nuclear magnetic resonance spectroscopy, mass spectrometry, and elemental analysis methods. Their enantiomeric excesses were determined by the chiral high-performance liquid chromatography method. Both keto alcohols and their corresponding chiral diols synthesized can be used as chiral starting materials and chiral source materials or intermediates in the synthesis of many biologically active molecules, or they can be used as chiral ligands in asymmetric synthesis, serving as organocatalysts.

Synthesis of Raspberry-like Nanoparticles via Surface Grafting of Positively Charged Polyelectrolyte Brushes: Colloidal Stability and Surface Properties.

A method to synthesize stable, raspberry-like nanoparticles (NPs), using surface grafting of poly(glycidyl methacrylate) (PGMA) brushes on a polystyrene (PS) core with varying grafting densities, is reported. A two-step functionalization reaction of PGMA epoxide groups comprising an amination step first using ethylene diamine and then followed by a quaternization using glycidyltrimethylammonium chloride generates permanently and positively charged polyelectrolyte brushes, which result in both steric and electrostatic stabilization. The dispersion stability of the brush-bearing NPs is dramatically improved compared to that of the pristine PS core in salt solutions at ambient (25 °C) and elevated temperatures (60 °C). Additionally, the grafted polyelectrolyte chains undergo a reversible swelling in the presence of different ionic strength (IS) salts, which modulate the surface properties, including roughness, stiffness, and adhesion. An atomic force microscope under both dry and wet conditions was used to image conformational changes of the polyelectrolyte chains during the swelling and deswelling transitions as well as to probe the nanomechanical properties by analyzing the corresponding force-sample separation curves. The quaternized polyelectrolyte brushes undergo a conformational transition from a collapsed state to a swelled state in the osmotic brush (OB) regime triggered by the osmotic gradient of mobile ions to the interior of the polymer chain. At IS ∼ 1 M, the brushes contract and the globules reform (salted brush state) as evidenced by an increase in the surface roughness and a reduction in the adhesion of the brushes. Beyond IS ∼ 1 M, quartz crystal microbalance with dissipation monitoring measurements show that salt uptake continues to take place predominantly on the exterior surface of the brush since salt adsorption is not accompanied by a size increase as measured by dynamic light scattering. The study adds new insights into our understanding of the behavior of NPs bearing salt-responsive polyelectrolyte brushes with adaptive swelling thresholds that can ultimately modulate surface properties.

Fundamentals of NO reduction by liquid wastes: The first application in hazardous waste incineration

To meet increasingly stringent standards of Nitrogen oxide (NOx), it is highly desirable to develop high-efficiency denitration technology during hazardous waste incineration. Therefore, a state-of-art decoupling combustion technology of liquid hazardous wastes (LHW) has been proposed to achieve low NOx emission. In this technology, LHW is introduced into a low-NOx reactor to reduce NOx generated from solid hazardous waste (SHW) incineration prior to its complete combustion. The present article is devoted to clarifying the optimal conditions for denitration reactions by LHW, so the capabilities of nitric oxide (NO) reduction by reduction by LHW model compounds, namely methanol and methylbenzene, were evaluated in fixed-bed and fluidized-bed reactors. The highest denitration efficiency is 78.9% at 900 °C for methanol and 70.0% at 1000 °C for methylbenzene in the test temperature range. The NO reduction activities were closely associated with cracking characteristics of LHW. The presence of oxygen (O2) exhibited different effects on denitration: it promoted NO reduction at low temperatures due to the generation of more denitration-favored agents but suppressed NO reduction at high temperatures due to the oxidation of denitration-favored agents into CO2 and H2O by excessive O2. Moreover, the fluidized-bed reactor, characterized by good heat transfer, exhibited an approximately 17% higher NO reducing efficiency compared to the fixed-bed reactor at low temperatures, but both reactors demonstrated similar NO reduction efficiencies of around 83% at high temperatures. In addition, methanol and methylbenzene showed higher NO reduction efficiencies than their cracking-produced reducing gases, with the reducing gases accounting for approximately 50% of the overall NO reduction efficiency at 1000 °C. According to the above results, a two-step denitration reaction pathway was proposed in which both cracking-formed free radicals and reducing gases contribute to the overall NO reduction. The results of this study can provide valuable insights for NO reduction in the hazardous waste disposal.

Synthesis, crystal structure and Hirshfeld surface analysis of N-(6-acetyl-1-nitro-naphthalen-2-yl)acetamide.

The title compound, C14H12N2O4, was obtained from 2-acetyl-6-amino-naphthalene through two-step reactions of acetyl-ation and nitration. The mol-ecule comprises the naphthalene ring system consisting of functional systems bearing a acetyl group (C-2), a nitro group (C-5), and an acetyl-amino group (C-6). In the crystal, the mol-ecules are assembled into two-dimensional sheet-like structures by inter-molecular N-H⋯O and C-H⋯O hydrogen-bonding inter-actions. Hirshfeld surface analysis illustrates that the most important contributions to the crystal packing are from O⋯H/H⋯O (43.7%), H⋯H (31.0%), and C⋯H/H⋯C (8.5%) contacts.

Extensive optical and DFT studies on novel AIE active fluorescent sensor for Colorimetric and fluorometric detection of nitrobenzene in Solid, solution and vapor phase

An electron rich isophthalamide based sensor IPA has been synthesized through a simple two-step reaction, containing noteworthy aggregation induced emission (AIE) properties. Considering the significant emission with λmax at 438 nm, sensor IPA has been employed for the sensing of nitrobenzene (NB) in solid, solution and vapor state with high sensitivity and selectivity. Sensor IPA showed noteworthy colorimetric and fluorometric quenching in fluorescence emission when exposed to NB. Small size of NB and involvement of photoinduced electron transfer (PET) lead to detection of NB down to 60 nM. IPA-NB interaction was studied through UV–Vis. spectroscopic studies along with fluorescence spectroscopy. Moreover, 1H and 13C NMR titration experiments provided additional support for determination of interaction type. Furthermore, by using density functional theory (DFT) calculations, thermodynamic stability was studied. Additionally, non-covalent interactions (NCI), frontier molecular orbitals (FMO), density of states (DOS), were investigated for providing further evidence of nitrobenzene sensing and its interaction with sensor. Natural bond orbital (NBO) analysis was carried out for charge transfer studies. Quantum theory of atom in molecule (QTAIM) and SAPT0 studies provided information about interaction points and binding energy. Additionally, IPA was investigated for NB sensing in real water samples, and its effective participation in solid state on-site detection as well as in solution phase was brought to light along with logic gate construction.

Direct Access to Thio- and Seleno-acetamides Bearing (Benzo)thiazoles by a Base-Promoted One-Pot Two-Step Three-Component Reaction of 2-Amino(benzo)thiazoles with Aryl Acetyl Chlorides and Dichalcogenides.

Highly efficient and practical carbon-chalcogen (S, Se) and amide bonds formation methodologies for the synthesis of thio- and seleno-acetamides were developed, via the base-promoted one-pot two-step reactions of 2-amino(benzo)thiazoles and aryl acetyl chlorides with dichalcogenides. This cross-coupling reaction afforded the goal products that had been chalcogenated regioselectively in moderate to good yields. Further transformations of the new synthesized compounds, DFT calculations and preliminary mechanism studies are discussed as well.

Highly sensitive and specific detection of Ni2+ using a novel fluorometric probe in the DMSO-H2O system.

The rapid detection of Ni ions has important research and application value. This paper presents a novel specific turn-off fluorescence probe PCTMP-FS for detecting Ni2+ ions. The carbazole-based compound PCTMP is first synthesized via a two-step reaction. PCTMP-FS comprises PCTMP dispersed into a DMSO-H2O (fw=30% v/v) mixed solvent. The probe demonstrates prominent selectivity and anti-interference abilities for detecting Ni2+ with a limit of detection (LOD) of 0.233μM. The probe exhibits good applicability over a wide range of acidities. The detecting mechanism of the probe is due to the complex formed by PCTMP and Ni2+ (2:1), which destroys intramolecular charge transfer in the compound. The probe has good repeatability and demonstrates excellent stability and sensitivity for the detection of Ni2+ in real water samples.

Synthesis of 5-methyl-4-polyfluoroaryl-1,3-thiazol-2-amines

1-(Polyfluoroaryl)propan-1-ones were transformed into 5-methyl-4-polyfluoroaryl-1,3-thiazol-2-amines by a twostep reaction sequence involving formation of 2-bromo-1- (polyfluoroaryl)propan-1-ones under the acidic bromination conditions followed by heterocyclization with thiourea to finally afford new 5-methyl-4-polyfluoroaryl-1,3-thiazol-2- amines in high yields. 1,1'-(2,3,5,6-Tetrafluoro-1,4-phenylene)- dipropan-1-one was involved in the similar reaction to give a derivative containing two thiazole moieties.

Synthesis, Characterization, Molecular Docking Studies and Biological Evaluation of Thiazole Schiff Base Analogs

In this work, potentially safe few Schiff base compounds containing a thiazole moiety were synthesized and characterized. Three thiazole derivatives (2a-c) were successfully synthesized through a two-step reaction involving substituted benzaldehyde, thiosemicarbazide and 1,3-dichloroacetone. The elucidation of the synthesized compounds was accomplished by using spectral studies. Antimicrobial activities demonstrated that some compounds exhibited moderate effectiveness against microbes, compared to the standard antibiotic’s ceftriaxone and amphotericin B, using the disc diffusion technique. In the DPPH free radical scavenging assay, all compounds displayed promising antioxidant effectiveness. Moreover, the molecular docking studies showed that thiazole Schiff base analogs effectively bind to potential receptor binding sites.

Harnessing bimetallic oxide nanoparticles on ionic liquid functionalized silica for enhanced catalytic performance

The present study reports on harnessing bimetallic (V and Ni) oxide nanoparticles supported on ionic liquid-functionalized silica for enhancing catalytic performance in epoxidation and hydrogenation reactions. The as-synthesized catalyst was ably characterized through various techniques such as FTIR, X-ray diffraction (XRD), N2 adsorption−desorption isotherms, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). A selective organic transformation of Isophorone to Homalinol via two-steps tandem reaction significantly promoted by synthesized catalyst. During epoxidation and hydrogenation reactions, V-NiNPs@SILP catalyst demonstrated excellent catalytic performance, leading to 98.23 % conversion with 99.06 % selectivity. Moreover, the synthesized catalyst exhibited recyclability for five consecutive cycles with minute loss in activity.

Development of on-DNA Formation of Benzofuran for DNA-Encoded Library Synthesis.

Using a novel homologation-heterocyclization cascade, the on-DNA synthesis of benzofurans from aldehydes has been developed. The methodology, based on an innovative use of the Seyferth-Gilbert homologation, followed by a high yielding Sonogashira coupling in situ intramolecular cyclization one-pot, two-step reaction, provides a powerful and unique pathway for DNA-encoded library (DEL) synthesis of a wide array of pharmaceutically relevant benzofuran-based scaffolds.

Investigation into the Structure and Properties of Biochar Co-Activated by ZnCl2 and NaHCO3 under Low Temperature Conditions.

Using sodium lignosulfonate as feedstock, ZnCl2 and NaHCO3 co-activated the hierarchical porous carbons (HPCs) were prepared by one-pot pyrolysis with different NaHCO3 dosages (0-4 g) and carbonization temperatures (400-600 °C). Subsequently, phosphotungstate (HPW) was supported with the resulting biochar for the α-pinene hydration reaction to produce α-terpineol. The optimum preparation conditions were determined according to the yield of α-terpineol. The formation mechanism and physicochemical properties of HPCs were analyzed through TG, SEM, XPS, XRD, FT-IR, and N2 adsorption-desorption isotherms. The results demonstrated that NaHCO3 underwent a two-step reaction which liberated a substantial quantity of CO2, thereby enhancing activated carbon's macroporous and mesoporous structures. Simultaneously, NaHCO3 mitigated strong acid gas (HCl) emissions during ZnCl2 activation. Compared with AC450-4:8:0 prepared by ZnCl2 activation alone, the total pore volume of AC450-4:8:2 prepared by co-activation is increased from 0.595 mL/g to 0.754 mL/g and the mesopore rate from 47.7% to 77.8%, which is conducive to reducing the steric hindrance of the hydration reaction and improving the selectivity. Hydration experiments show that the selectivity of α-terpineol is 55.7% under HPW/AC450-4:8:2 catalysis, higher than 31.0% for HPW and 47.4% for HPW/AC450-4:8:0.

Peptide and Enzyme Catalysts Work in Concert in Stereoselective Cascade Reactions-Oxidation followed by Conjugate Addition.

Enzymes and peptide catalysts consist of the same building blocks but require vastly different environments to operate best. Herein, we show that an enzyme and a peptide catalyst can work together in a single reaction vessel to catalyze a two-step cascade reaction with high chemo- and stereoselectivity. Abundant linear alcohols, nitroolefins, an alcohol oxidase, and a tripeptide catalyst provided chiral γ-nitroaldehydes in aqueous buffer. High yields (up to 92 %) and stereoselectivities (up to 98 % ee) were achieved for the cascade through the rational design of the peptide catalyst and the identification of common reaction conditions.

Temporal (Dis)Assembly of Peptide Nanostructures Dictated by Native Multistep Catalytic Transformations.

Emergence of complex catalytic machinery via simple building blocks under non-equilibrium conditions can contribute toward the system level understanding of the extant biocatalytic reaction network that fuels metabolism. Herein, we report temporal (dis)assembly of peptide nanostructures in presence of a cofactor dictated by native multistep cascade transformations. The short peptide can form a dynamic covalent bond with the thermodynamically activated substrate and recruit cofactor hemin to access non-equilibrium catalytic nanostructures (positive feedback). The neighboring imidazole and hemin moieties in the assembled state rapidly converted the substrate to product(s) via a two-step cascade reaction (hydrolase-peroxidase like) that subsequently triggered the disassembly of the catalytic nanostructures (negative feedback). The feedback coupled reaction cycle involving intrinsic catalytic prowess of short peptides to realize the advanced trait of two-stage cascade degradation of a thermodynamically activated substrate foreshadows the complex non-equilibrium protometabolic networks that might have preceded the chemical emergence of life.