Reduced Form Research Articles

Synthesis, Characterization and Biological Activity of novel 3-benzyl-2- (4'-substituted phenyl)-4(5H)-(4''-nitrophenyl amino)-1, 3-oxazolidines

Here, we describe the design, synthesis, and biological evaluation of oxazolidine derivatives. Oxazolidine ring is a reduced form of oxazole system; many of its derivatives possess interesting biological activities, such as anti-convulsant, anti-microbial, analgesic, anti-inflammatory and anti-tumor. In our study, the biological activity of synthesized novel 3-benzyl-2-(4'-substituted phenyl)-4(5H)-(4''-nitrophenyl amino)-1, 3-oxazolidines 6a-e were characterized by antimicrobial screening against several gram-positive, gram negative bacteria and fungus. The purity of the synthesized compounds was characterized by means of IR, 1H-NMR, mass spectral and elemental analysis. Antimicrobial screening for all the compounds exhibits characteristic microbial inhibition against Bacillus lentus, Micrococcus luteus, Bacillus cereus, Staphylococcus albus, Escherichia coli, Klebsiella aerogenes, Salmonella paratyphi, Proteus vulgaris and Candida albicans

Universal moiré buckling of freestanding 2D bilayers

The physics of membranes, a classic subject, acquires new momentum from two-dimensional (2D) materials multilayers. This work reports the surprising results emerged during a theoretical study of equilibrium geometry of bilayers as freestanding membranes. While ordinary membranes are prone to buckle around compressive impurities, we predict that all 2D material freestanding bilayers universally undergo, even if impurity-free, a spontaneous out-of-plane buckling. The moiré network nodes here play the role of internal impurities, the dislocations that join them giving rise to a stress pattern, purely shear in homobilayers and mixed compressive/shear in heterobilayers. That intrinsic stress is, theory and simulations show, generally capable to cause all freestanding 2D bilayers to undergo distortive bucklings with large amplitudes and a rich predicted phase transition scenario. Realistic simulations predict quantitative parameters expected for these phenomena as expected in heterobilayers such as graphene/hBN, [Formula: see text] heterobilayers, and for twisted homobilayers such as graphene, hBN, [Formula: see text]. Buckling then entails a variety of predicted consequences. Mechanically, a critical drop of bending stiffness is expected at all buckling transitions. Thermally, the average buckling corrugation decreases with temperature, with buckling-unbuckling phase transitions expected in some cases, and the buckled state often persisting even above room temperature. Buckling will be suppressed by deposition on hard attractive substrates, and survives in reduced form on soft ones. Frictional, electronic, and other associated phenomena are also highlighted. The universality and richness of these predicted phenomena strongly encourages an experimental search, which is possible but still missing.

Evaluation of morphological, structural, thermal, electrical, and chemical composition properties of graphene oxide, and reduced graphene oxide obtained by sequential reduction methods

This study investigates the preparation and characterization of reduced graphene oxide (RGO) derived from graphene oxide (GO) using various reduction methods, including ethylene glycol (EG), hydrazine, ascorbic acid, thermal reduction, and their sequential combinations. Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric analysis (TGA), Raman spectroscopy, and X-ray Photoelectron Spectroscopy (XPS) were employed to analyze the morphological, structural, and thermal properties, as well as the composition and the functional groups of graphene oxide and its reduced forms. The highest electrical conductivity value of about 2500 S/m was obtained after the combined ascorbic acid-ethylene glycol-hydrazine treatment, which is attributed to the increase in C/O ratio determined by XPS compositional analysis and the decrease in area defects, as confirmed by Raman analysis.

Different sensitivities of porcine coronary arteries and veins to BAY 60–2770, a soluble guanylate cyclase activator

Nitric oxide (NO)-donor drugs, which stimulate reduced form of soluble guanylate cyclase (sGC), have different efficacy to the arteries and veins. This study examined whether sGC activators, which activate oxidized/apo sGC, also have arteriovenous selectivity similar to that of NO-donor drugs. The mechanical responses of the isolated blood vessels were assessed using the organ chamber technique and protein expression was verified using western blotting. BAY 60–2770 (sGC activator) caused concentration-dependent relaxation in both porcine coronary arteries and veins, with the response being slightly more pronounced in the arteries. In contrast, sodium nitroprusside (NO-donor drug)-induced relaxation of the arteries was slightly weaker than that of the veins. Vasorelaxant responses to 8-Br-cGMP (cGMP analog) did not differ between the arteries and veins. In the presence of ODQ (heme oxidant), the heterogeneities in the responses to BAY 60–2770 and sodium nitroprusside between the arteries and veins disappeared. The sGC expression in the arteries did not differ from that in the veins. These findings suggest that sGC activators, in contrast to NO-donor drugs, have greater effects on the arteries than on the veins. This may be due to differences in the balance of sGC forms expressed in the arteries and veins.

The microbial phosphorus cycle in aquatic ecosystems.

Phosphorus is an essential element for life, and phosphorus cycling is crucial to planetary habitability. In aquatic environments, microorganisms are a major component of phosphorus cycling and rapidly transform the diverse chemical forms of phosphorus through various uptake, assimilation and release pathways. Recent discoveries have revealed a more dynamic and complex aquatic microbial phosphorus cycle than previously understood. Some microorganisms have been shown to use and produce new phosphorus compounds, including those in reduced forms. New findings have also raised numerous unanswered questions that warrant further investigation. There is an expanding influence of human activity on aquatic ecosystems. Advancements in understanding the phosphorus biogeochemistry of evolving aquatic environments offer a unique opportunity to comprehend, anticipate and mitigate the effect of human activities. In this Review, I discuss the wealth of new aquatic phosphorus cycle research, spanning disciplines from omics and physiology to global biogeochemical modelling, with a focus on the current comprehension of how aquatic microorganisms sense, transport, assimilate, store, produce and release phosphorus. Of note, I delve into cellular phosphorus allocation, an underexplored topic with wide-ranging implications for energy and element flux in aquatic ecosystems.

Experimental in vivo models for understanding inter-molecular interactions and preventing multifactor disease development

The increased spontaneous fragility in the centromere regions of the chromosomes predisposes to abnormal cellular division due to abnormal interaction with the mitotic spindle, which leads to number chromosomal aberrations. The abnormal structure of the microtubule-associated proteins (MAPs) could also be among the internal factors, predisposing to these pathologies. On the other hand, the increased frequency of the spontaneous chromosomal fragility suggests abnormal structure of the respective chromosomal/chromatin components and thus an increased risk about gene mutations and structural chromosomal aberrations. The spontaneous chromosomal fragility was tested by light microscopy observation of metaphases from peripheral blood lymphocytes of 8 patients with polygene pathologies (neoplasms, neuro-degenerative diseases, and neuro-psychiatric disorders) and of 18 healthy controls. In the tested patients was established significantly higher frequency of the spontaneous chromosomal fragility, including in the centromere chromosomal regions, compared to the controls. Different inter-molecular interactions, which could prevent the pathology appearance, were investigated by appropriate experimental in vivo models. As a whole, in the most cases, the presented data showed significantly lower average titers of anti-ganglioside antibodies and gangliosides in the samples from myocardium and liver than in the samples from brain and pancreas. By taking into consideration that the myocardium and liver are known as the most enriched of GSH anatomic organs, the presented data could be explained with the literature messages of higher amounts of de novo-synthesized free GSH tri-peptide in the same two organs. Moreover, a possibility about the production of antibodies/immunoglobulins by non-lymphoid types of cells, tissues, and organs in appropriate conditions was shown. Because the so-produced antibodies are out of the germinative centers in the specialized lymphoid tissues and organs, the control of their functions by small ions and molecules as gangliosides is very important. In the current study, the attention was particularly directed to the iteractions with the participation of gangliosides, the reduced form of the tri-peptide glutathione (GSH), and the protein HACE1. Besides the tumor-suppressor activity of protein HACE1, also its neuroprotective influence was proven, namely by interactions with specific molecules.

Sewage-and fertilizer-derived nutrients alter the intensity, diversity, and toxicity of harmful cyanobacterial blooms in eutrophic lakes.

Cyanobacterial harmful algal blooms (CHABs) are promoted by excessive nutrient loading and, while fertilizers and sewage are the most prevalent external nutrient sources in most watersheds, the differential effects of these nutrient sources on CHABs are unknown. Here, we tracked CHABs and performed experiments in five distinct lakes across the Northern US including Lake Erie. Fertilizers with ammonium and orthophosphate, membrane (0.2 μm)-filtered sewage (dominated by reduced forms of nitrogen) sand-and membrane-filtered sewage (dominated by nitrate), and an inorganic nutrient solution of ammonium and orthophosphate were used as experimental nutrient sources for CHABs at N-equivalent, environmentally realistic concentrations. Phytoplankton communities were evaluated fluorometrically, microscopically, and via high throughput sequencing of the 16S rRNA gene, and levels of microcystin and the δ15N content of particulate organic nitrogen (δPO15N) were quantified. Fertilizer and both sources of wastewater increased the abundance of cyanobacteria in all experiments across all five lakes (p < 0.05 for all) whereas effects on eukaryotic phytoplankton were limited. Sand-filtered sewage contained less P, organic matter, and ammonium but more nitrate and had a 25% less potent stimulatory effect on cyanobacteria than membrane-filtered sewage, suggesting nitrification may play a role in reducing CHABs. Fertilizer increased microcystin levels and decreased the δPO15N whereas wastewater increased δPO15N (p < 0.05 for all). Microcystis was the genus most consistently promoted by nutrient sources (p < 0.05 in all experiments), followed by Cyanobium (p < 0.05 in 50% of experiments), with increases in Microcystis biomass consistently elicited by membrane-filtered wastewater. Collectively, results demonstrate that differing types of sewage discharge and fertilizers can promote CHAB intensity and toxicity, while concurrently altering CHAB diversity and δPO15N. While membrane-filtered sewage consistently favored Microcystis, the discharge of sewage through sands muted bloom intensity suggesting sand-beds may represent a tool to remove key nutrients and partially mitigate CHABs.

Fluoride Ions Sequestration From Contaminated Water Using PVA‐Agar‐Based Green Anion‐Exchanger

AbstractThe current work is focused on the designing of a green interpenetrating polymer network (IPN) PA@polyAAm:AN using polyvinyl alcohol‐agar hybrid backbone and its subsequent conversion into an anion‐exchanger PA@polyAAm:AN‐AE through reduction of nitrile group in presence of LiAlH4. Further, the reduced form of IPN was quaternized using methyl iodide so that anion to anion exchange could take place between F− and I− anions. The primary objective of synthesizing an anion‐exchanger was to eliminate F− ions from contaminated water through the utilization of a prepared device. During the optimization of different experimental parameters for getting the optimal anion‐exchange capacity (AEC), the favorable conditions found were: pH, 9.0; contact period, 120 min; adsorbent dosage, 30 mg and initial F− ion concentration, 8.0 mg L−1. The pseudo‐second order kinetic model best described the F− ions adsorption kinetics, with a 0.97 R2 value. The rate constant (KF) was found to be 2.3, which further supported the validity of the Freundlich isotherm. Thus, the current study has remarkable potential with a 79.99% adsorption capacity for eliminating F− ions. Moreover, the ecofriendly anion‐exchanger prepared was found effective in the removal of F− ions from aqueous medium up to four cycles during reusability analysis.

Towards Understanding the Motivators of Sustainable Consumer Behavior-Validation of the Food Eco-Guilt Scale.

The growing concern about the environmental impacts of consumption has led to the emergence of so-called "eco-guilt"-a psychological construct reflecting the guilt felt by individuals about the environmental consequences of their choices, which plays a prominent role among the factors influencing pro-environmental behavior. Although eco-guilt has already emerged in other service sectors, such as tourism, and general scales exist to measure it, no such scale exists in the context of food consumption. The aim of this research is to develop and validate a scale to measure eco-guilt related to food consumption. To create the scale in an objective way, we used the Sustainable Development Goals as a framework. Data were collected from university students; a questionnaire was completed online by 367 respondents. The responses were analyzed from several different perspectives, using multiple methods following the principle of triangulation. For the data analysis, the Psych and Mokken packages of R software (version 4.4.0) were used. The constructed scale was based on 13 items. An overview of the reliability of the scale was provided using various indicators (e.g., Cronbach's α = 0.86, ωh = 0.63, ωH asymptotic = 0.71, and ωt = 0.89). Based on the analyses, we proposed a reduced form with nine items for the measurement of food-related eco-guilt. The results of this research provide a scale to help understand what motivates consumers to make more sustainable consumption choices. Moreover, the scale is relevant to future research focused on understanding how guilt influences future food choices.

Electric potential energy optimized 3D radial sampling trajectories for MRI

A novel method for creating “golden” 3D center-out radial MRI sampling trajectories was developed and analyzed. This method, called ELECTRO (ELECTRic potential energy Optimized), uses repulsive forces to minimize electric potential energy. An objective function \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:G\\left(S\\right)$$\\end{document}, the electric potential energies of all subsets of consecutive readouts in a 3D radial trajectory, and its reduced form were minimized using a multi-stage optimization strategy. A metric called normalized mean nearest neighbor angular distance (NMNA) was proposed for describing distributions of points on a sphere. ELECTRO and other relevant golden trajectories were compared in silico using NMNA and point spread function analysis. Consecutive readouts from an ELECTRO trajectory were well spread out, with consistent NMNA values across sphere sizes (σNMNA = 0.005) and between regions on the sphere (NMNA ≈ 1.49). Conversely, the supergolden trajectory had poor consistency in NMNA values (σNMNA = 0.090) and clustering (NMNA = 1.28 at the pole with 40,000 readouts) that lead to artifact in the point spread function. Multi-stage optimization was faster than single-stage and obtained lower values of \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:G\\left(S\\right)$$\\end{document} (e.g., 0.87 vs. 0.91, for a sphere size of 40). In conclusion, ELECTRO trajectories are more golden than other 3D center-out radial trajectories, making them a suitable candidate for dynamic 3D MR imaging.

Alpha-Lipoic Acid: Biological Mechanisms and Health Benefits.

Alpha-lipoic acid (ALA) is a bioactive molecule with significant health effects. The biological action of ALA has been ascribed to the characteristic antioxidant properties of the oxidized form (ALA) and its reduced counterpart the dihydrolipoic acid (DHLA) system. The ALA/DHLA combination represents an ideal antioxidant since it can quench radicals, is able to chelate metals, is amphiphilic, and has no major adverse effects. This unique system is able to scavenge reactive oxygen species, exerting a major effect on tissue levels of reduced forms of other antioxidants, including glutathione. For this reason, ALA is also known as the "antioxidant of antioxidants". This review analyzes the antioxidant, anti-inflammatory, and neuroprotective effects of ALA and discusses its applications as an ameliorative tool for chronic diseases and those associated with oxidative stress. Results from in vitro and in vivo studies demonstrated that ALA modulates various oxidative stress pathways suggesting its application, alone or in combination with other functional substances, as a useful support in numerous conditions, in which the balance oxidant-antioxidant is disrupted, such as neurodegenerative disorders. Based on several successful clinical studies, it has been also established that oral ALA supplements are clinically useful in relieving the complications of diabetes and other disorders including cardiovascular diseases and nerve discomforts suggesting that ALA can be considered a useful approach to improving our health.

The dimer of human SVCT1 is key for transport function

Humans and other primates lack the ability to synthesize the essential nutrient, Vitamin C, which is derived exclusively from the diet. Crucial for effective vitamin C uptake are the Na+ dependent Vitamin C transporters, SVCT1 and SVCT2, members of the nucleobase ascorbate transporter (NAT) family. SVCT1 and 2 actively transport the reduced form of Vitamin C, ascorbic acid, into key tissues. The recent structure of the mouse SVCT1 revealed the molecular basis of substrate binding and that, like the other structurally characterised members of the NAT family, it exists as a closely associated dimer. SVCT1 is likely to function via the elevator mechanism with the core domain of each protomer able to bind substrate and move through the membrane carrying the substrate across the membrane. Here we explored the function of a range of variants of the human SVCT1, revealing a range of residues involved in substrate selection and binding, and confirming the importance of the C-terminus in membrane localisation. Furthermore, using a dominant negative mutant we show that the dimer is essential for transport function, as previously seen in the fungal homologue, UapA. In addition, we show that a localisation deficient C-terminal truncation of SVCT1 blocks correct localisation of co-expressed, associated wildtype SVCT1. These results clearly show the importance of the dimer in both correct SVCT1 trafficking and transport activity.

Mechanism of action and impact of thiol homeostasis on efficacy of an enzyme replacement therapy for classical homocystinuria

Homocystinuria (HCU) due to cystathionine beta-synthase (CBS) deficiency is characterized by elevated plasma and tissue homocysteine levels. There is no cure, but HCU is typically managed by methionine/protein restriction and vitamin B6 supplementation. Enzyme replacement therapy (ERT) based on human CBS has been developed and has shown significant efficacy correcting HCU phenotype in several mouse models by bringing plasma total homocysteine below the clinically relevant 100 μM threshold. As the reactive nature of homocysteine promotes disulfide formation and protein binding, and ERT is unable to normalize plasma total homocysteine levels, the mechanism of action of ERT in HCU remains to be further characterized. Here we showed that only a reduced homocysteine serves as a substrate for CBS and its availability restricts the homocysteine-degrading capacity of CBS. We also demonstrated that cells export homocysteine in its reduced form, which is efficiently metabolized by CBS in the culture medium. Availability of serine, a CBS co-substrate, was not a limiting factor in our cell-based model. Biological reductants, such as N-acetylcysteine, MESNA or cysteamine, increased the availability of the reduced homocysteine and thus promoted its subsequent CBS-based elimination. In a transgenic I278T mouse model of HCU, administration of biological reductants significantly increased the proportion of protein-unbound homocysteine in plasma, which improved the efficacy of the co-administered CBS-based ERT, as evidenced by significantly lower plasma total homocysteine levels. These results clarify the mechanism of action of CBS-based ERT and unveil novel pharmacological approaches to further increase its efficacy.

Antioxidant system of the liver of male rats at different stages of ontogenesis under conditions of chronic exposure to low-intensity electromagnetic field

Currently, the World Health Organization (WHO) recognizes that radio frequency electromagnetic fields (RF EMF) are one of the most common sources of electromagnetic radiation and are significant factors for human health, having a pronounced biological effect. In addition, oxidative stress caused by hyperproduction of free radicals due to exposure to RF EMF is a factor that provokes the development of many diseases and, in particular, liver pathologies, including in the elderly.For the first time, studies were conducted on the state of the antioxidant system of the liver of male rats at various stages of postnatal development (young, adult, aging and pre-senile periods) under conditions of chronic exposure to EMF from a Wi-Fi device (2,45 GHz, PD=0,79±0,52 μW/cm2, 24 h/day, daily) from the age of 50 days until they reach 24 months. In the cytosolic-microsomal fraction, the activity of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione-S-transferase was determined by spectrophotometry, and in the tissue homogenate, the concentration of protein-bound glutathione, sulfhydryl groups of proteins, total SH groups, reduced glutathione and protein oxidation products was determined.The revealed changes in the state of the liver antioxidant system during chronic exposure to EMF from Wi-Fi equipment on the body during aging indicate activation of the glutathionedependent system in experimental animals. The revealed changes are manifested in maintaining a stably elevated level of the reduced form of thiols in the liver tissue and are an adaptive response of cells to prolonged exposure of the body to EMF from Wi-Fi equipment.

Structure and functional studies of Avt1, a novel peptide from the sea anemone Aulactinia veratra

Sea anemones are a rich source of peptide toxins spanning a diverse range of biological activities, typically targeting proteins such as ion channels, receptors and transporters. These peptide toxins and their analogues are usually highly stable and selective for their molecular targets, rendering them of interest as molecular tools, insecticides and therapeutics. Recent transcriptomic and proteomic analyses of the sea anemone Aulactinia veratra identified a novel 28-residue peptide, designated Avt1. Avt1 was produced using solid-phase peptide synthesis, followed by oxidative folding and purification of the folded peptide using reversed-phase high-performance liquid chromatography. The liquid chromatography-mass spectrometry profile of synthetic Avt1 showed a pure peak with molecular mass 6 Da less than that of the reduced form of the peptide, indicating the successful formation of three disulfide bonds. The solution structure determined by NMR revealed that Avt1 adopts an inhibitor cystine knot (ICK) fold, in which a ring is formed by two disulfide bonds with a third disulfide penetrating the ring to create the pseudo-knot. This structure provides ICK peptides with high structural, thermal and proteolytic stability. Consistent with its ICK structure, Avt1 was resistant to proteolysis by trypsin, chymotrypsin and pepsin, although it was not a trypsin inhibitor. Avt1 at 100 nM showed no activity in patch–clamp electrophysiological assays against several mammalian voltage-gated ion channels, but has structural features similar to toxins targeting insect sodium ion channels. Although sequence homologues of Avt1 are found in a number of sea anemones, this is the first representative of this family to be characterised structurally and functionally.

EARLY DIAGENESIS GEOCHEMISTRY OF BOTTOM SEDIMENTS IN THE PLEISTOCENE CORE OF LAKE KOTOKEL (Eastern Baikal Region)

Chemical composition of bottom sediments and pore waters of organic-mineral sediments (sapropel) of Lake Kotokel (Eastern Baikal region) has been studied, based on long drilling cores, 14.5 and 16.5 m. A reduction type of diagenesis has been established, during which destruction of organic matter, transformation of the chemical composition of pore waters and the formation of authigenic minerals occur. Even in the uppermost intervals of sapropel, organic matter is being profoundly transformed and differs significantly in composition from that of bioproducers (plankton). The major role in diagenetic transformations of organic matter belongs to different physiological groups of microorganisms, primarily heterotrophic, amonifying and sulfate-reducing bacteria. During diagenesis, the basic chemical composition of pore waters (HCO3–, SO42–, Cl–, Ca2+, Mg2+, K+, Na+) changes, trace elements (Fe, Mn, Sr, Ba, Pb, As, Co, Ni) redistribute, concentrations of HCO3–, NH4+, PO43− and Si increase; this is caused by destruction of organic matter. In the process of bacterial sulfate reduction in pore waters, the concentration of SO42– decreases along the depth of the section, and in the sediment the proportion of reduced forms of sulfur increases and the isotopic composition of sulphur δ34S changes. Transformation of chemical composition of pore waters and the activity of microorganisms leads to the formation of authigenic pyrite, rhodochrosite, and barite.

Generation of Solitary Waves with Analytical Solution for The (3+1)-dimensional pKP-BKP Equation and Reductions

In this study, new solitary wave solutions are obtained for the combination of the B-type Kadomtsev-Petviashvili (BKP) equation and the potential Kadomtsev-Petviashvili (pKP) equation, called the integrable (3+1)-dimensional coupled pKP-BKP equation, and its two reduced forms. For this purpose, the Bernoulli auxiliary equation method, which is an ansatz-based method, is used. As a result, kink, lump, bright soliton and breather wave solutions are observed. It is concluded that this method and the results obtained for the considered pKP -BKP equations are an important step for further studies in this field.

Three new reduced forms of synthesized Schiff bases as potent anti-corrosion inhibitors for carbon steel in artificial seawater

As part of the development of a new organic entity, we synthesized three new reduced forms of Schiff bases named 2,2’-(((2,2-dimethylpropane-1,3-diyl)bis(azanediyl)bis(methylene)disphenol (I1), 4,4’-(((2,2-dimethylpropane-1,3-diyl)bis (azanediyl)bis(methylene)bis(2-methoxyphenol) (I2), and 6,6’-(((2,2-dimethylpropane-1,3-diyl) bis(azanediyl)bis(methylene)bis(2-methoxyphenol) (I3). In order to develop new organic ligands to inhibit steel corrosion in 1M HCl solution, various electrochemical methods, such as electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP), along with surface visualization through atomic force microscopy (AFM), were employed. PDP results revealed excellent inhibition by compound I3 (71%) at a concentration of 1 mg/L. These findings were supported by the observation of a protective layer formation during prolonged immersion of steel in a corrosive solution, with or without inhibitors. In addition to gaining insights into the interaction mechanism and adsorption mode, density functional theory, Monte Carlo, and molecular dynamic simulations were conducted, revealing valuable information about the interaction of the inhibitors with the steel surface. Average surface roughness (Ra) values obtained for the artificial seawater in the absence and presence of inhibitor are 887 nm for blank, 195 nm for I1, 158 nm for I2, and 105 nm for I3.

Generating globin-like reactivities in [human serum albumin-FeII(heme)] complex through N-donor ligand addition

Human serum albumin (HSA) has a strong binding affinity for heme b, forming a complex in a 1:1 ratio with the co-factor ([HSA-FeIIIheme]). This system displays spectroscopic and functional properties comparable to globins when chemical derivatives mimicking them are incorporated into the protein matrix. The aim of this study is to generate globin-like systems using [HSA-FeIIIheme] as a protein template and binding N-donor ligands (imidazole, Im; and 1-methylimidazole, 1-MeIm) to construct artificial [HSA-Fe(heme)-(N-donor)] complexes. Their electronic structure and binding thermodynamics are investigated using UV–vis and (synchronous) fluorescence spectroscopies, while ligand-protein interactions are visualized using docking simulations. The imidazole derivatives have a strong affinity for [HSA-FeIIIheme] (K ~ 104–106), where the spontaneous binding of Im and 1-MeIm are dominated by entropic and enthalpic effects, respectively. The reduced form of the [HSA-Fe(heme)-(N-donor)] complexes demonstrate nitrite reductase (NiR) activity similar to that observed in globins, but with significant differences in their rates. [HSA-FeIIheme-(1-MeIm)] reduces nitrite ~4× faster than the Im analogue, and ~ 30× faster than myoglobin (Mb). The enhanced NiR activity of [HSA-FeIIheme-(1-MeIm)] is a cumulative effect of several factors including a slightly expanded and more optimal heme binding pocket, nearby residues as possible proton sources, and a H-bonding interaction between 1-MeIm and residues Arg160 and Lys181 that may have a long-distance influence on the heme π electron density.

N-[(1RS)-Camphan-2-ylidene]-4-ethoxyaniline and its reduction product as stabilizers of nitrile butadiene rubbers

Objectives. To investigate the protective efficacy of unreduced and reduced forms of the condensation product of D,L-camphor and p-ethoxyaniline in nitrile butadiene rubber formulations when compared with the conventional stabilizer N-isopropyl-N′-phenyl- p-phenylenediamine aged under laboratory and in situ climatic conditions in the tropics.Methods. The thermostabilizing effect of the condensation product of D,L-camphor and p-ethoxyaniline was evaluated by means of infrared spectroscopy using the dynamics of changes in the absorption bands of carbonyl and hydroxyl groups. The features of rubber vulcanization were studied by means of rotorless rheometry. Changes in the physical and mechanical properties of rubbers and degree of cross-linking were evaluated after thermo-oxidative aging in laboratory conditions. They also took into account the results of longterm exposure of samples in undeformed and deformed state in a tropical climate, taking into account meteorological data of the Can Gio climatic testing station.Results. It was found for the first time that condensation products of D,L-camphor and p-ethoxyaniline exhibit a stabilizing effect in formulations of rubbers based on polar nitrile butadiene rubber.Conclusions. According to the results of laboratory and in situ tests, the study established that the use of N-[(1RS,2RS)-camphan-2-yl]- 4-ethoxyaniline (reduced form) as an antifatigue agent is preferable. This is due to the presence of a mobile hydrogen atom at the nitrogen atom. The protective effect is manifested in terms of the better preservation of elastic-strength properties of rubbers with less change in hardness.