Higher Carboxylic Acids Research Articles

Nanoscale mechanisms of carboxyl carbon preservation during Fe(II)-induced ferrihydrite transformation

The persistence of organic carbon (OC) in natural environments is widely attributed to OC associations with minerals such as iron (Fe) minerals. Carboxyl, a critical structure of OC, can form strong complexes with Fe minerals, but it is still largely unknown about the effects of carboxyl groups on the transformation of Fe oxides and the stabilization mechanisms of OC on Fe oxides at nanoscales. In this study, four carboxylic acids with varying numbers of carboxyl groups (2, 3, 4, and 27 carboxyls) and molecular weight (ranging from 100 to 2000 Da) were added during the coprecipitation of Fe oxides and OC. This approach was taken to systematically elucidate the nanoscale distribution and sequestration mechanisms of carboxyl-containing OC on Fe oxides over different aging periods. Results suggested that ferrihydrite transformed quickly into lepidocrocite, goethite, and magnetite with the presence of Fe(II). The transformation rate of lepidocrocite to goethite slowed with increasing carboxyl number in OC molecules for the low molecular weight carboxylic acids (100–300 Da), but the high molecular weight carboxylic acid (∼2000 Da) promoted ferrihydrite transformation into goethite. Meanwhile, the particle sizes of produced magnetite decreased with increasing carboxyl number in OC molecules. During the mineral transformation, the release of OC from Fe oxides to aqueous solution decreased with increasing numbers of carboxyl groups. Spherical aberration corrected scanning transmission electron microscopy (Cs-STEM) coupled with electron-energy-loss spectroscopy (EELS) suggested that carboxyl-rich OC promoted the formation of abundant defective or porous structures in goethite, resulting in OC accumulation in the bulk areas of goethite, which provided an effective way to sequester OC. The aggregation of high molecular weight OC containing more carboxyl groups with magnetite nanoparticles also played an important role in the preservation of OC. Furthermore, Fourier-transform infrared spectroscopy (FTIR) and near edge X-ray absorption fine structure spectroscopy (NEXAFS) indicated that OC may form bidentate binding with Fe oxides and the binding strength of Fe(III) and OC may change with varying numbers of carboxyl groups. Results in this study provided a comprehensive understanding of the dynamic interactions between OC with different numbers of carboxyl groups and Fe oxides, and shed insights into the nanoscale mechanisms of OC stabilization during Fe oxide transformation process.

Study of calcium-containing compounds as catalysts for the esterification of glycerol with higher carboxylic acids

Objectives. To investigate the catalytic activity of calcium-containing basic catalysts for the esterification of glycerol with higher carboxylic acids in order to develop a low-waste technology for the production of multifunctional additives, as well as to assess the possibility of using the reaction products for the processing of polyvinyl chloride.Methods. The consumption of oleic acid during synthesis was monitored using a titrimetric method of analysis with visual indication. The structure of the synthesized calcium-containing catalysts was confirmed by infrared spectroscopy; elemental analysis was additionally performed for calcium glyceroxide. Quantitative and qualitative analyses of the resulting mixtures of oleic acid glycerides were carried out using chromato-mass spectrometry. A sample of a multifunctional additive was tested in a model formulation of a medical plastic compound based on polyvinyl chloride.Results. It is shown that the catalytic activity of calcium derivatives in the reaction of esterification of glycerol with higher carboxylic acids increases in the series СаО < Са(ОН)2 < Ca(C17H33COO)2 < Ca(C2H5O)2 < Ca(C4H9O)2 < Ca(C3H7O3)2, while the use of calcium glyceroxide as a catalyst in an amount from 1 to 6 mol % increases the conversion of carboxylic acid from 58 to 86% in 10 h of synthesis. However, varying the amount of calcium glyceroxide from 1.5 to 6 mol % results in no observed changes in the conversion of carboxylic acid. The multifunctional additive obtained by selecting calcium glyceroxide as a catalyst has a thermally stabilizing and plasticizing effect on the polymer composition. The introduction of the developed additive into the formulation of a polyvinyl chloride composition for medical purposes reduces the processing torque and time to reach the dry point. By combining these factors, energy costs during production were reduced by more than 11% compared to the control composition.Conclusions. It is established that calcium alcoholates catalyze the reaction of esterification of glycerol with oleic (or higher) acid to increase the conversion of the initial substances and selectivity for the formation of monoglycerides as compared with calcium oxide, hydroxide, and oleate. By optimizing the ratio of glycerol : oleic acid : calcium glyceroxide at 1 : 1 : 0.015, the maximum conversion of oleic acid of up to 86% in 10 h was obtained via synthesis. The proposed method for esterification of glycerol with higher carboxylic acids in the presence of a calcium-containing catalyst avoids the stage of purification from the catalyst to obtain a composition with multifunctional additive properties for the processing of polyvinyl chloride.

Physicochemical characterizations, α-amylase inhibitory activities and inhibitory mechanisms of five bacterial exopolysaccharides

Inhibiting pancreatic α-amylase activity can decrease the release rate of glucose, thereby delaying postprandial blood glucose. This study aimed to investigate the physicochemical properties and porcine pancreatic α-amylase (PPA) inhibitory activities of five bacterial exopolysaccharides (EPSs). We also aimed to analyze the differences of their inhibitory activities, exploring the inhibition mechanism between EPSs and PPA. Five EPSs had a low molecular weight (55–66 kDa), which were mainly composed of mannose and glucose with total content exceeding 86 %. The IC50 values of five EPSs (0.162–0.431 mg/mL) were significantly lower than that of acarbose (0.763 mg/mL), indicating that the inhibitory effects of five EPSs on PPA were stronger than acarbose, especially the EPS from Bacillus subtilis STB22 (BS–EPS). Moreover, BS–EPS was a mixed-type inhibitor, whereas other EPSs were noncompetitive inhibitors of PPA. Five EPSs quenched the fluorophore of PPA by the mixed quenching or apparent static quenching. Interestingly, BS–EPS showed stronger binding affinity to PPA than other EPSs. It can be speculated that EPSs with low molecular weight, high carboxylic acid content, and α-glycosidic bond exhibited high PPA inhibitory activity. These results suggest that BS-EPS can effectively inhibit PPA activity and has potential applications in reducing postprandial hyperglycemia.

Bipolar Hydrogen Production from Biomass-Derived Aldehydes and Water in Flow Electrolyzers

It is critical to fight against global warming and confine it to a manageable level of +1.5°C by curbing CO2 emissions, eventually achieving zero net emissions by 2050. This target will involve significant efforts from all industry sectors and require renewable energy storage and conversion, most of which are heavily rely on clean hydrogen production. Water electrolysis, producing hydrogen and oxygen from water and electricity, is a promising route to the decarbonization of industry and transportation. The main source of energy loss in water electrolysis is the unfavorable thermodynamics (standard potential of 1.23 V vs. NHE) and slow kinetics of oxygen evolution reaction (OER). These challenges motivate us to design efficient paired electrolysis systems to substitute OER. In this work, we demonstrate an efficient bipolar hydrogen production system that combines cathodic hydrogen evolution from water and anodic hydrogen generation from aldehyde oxidation, at a low voltage (~0.1V) with co-generation of high valuable carboxylic acid. We used furfural as the model aldehyde, a biomass-derived compound that is produced on a large scale, currently on a scale of 0.43 million tons/year. Unlike conventional combined systems for hydrogen production that require high voltage (> 1.0 V) and are limited by mass transport (<100 mA cm−2) of reactants, this study doubled the hydrogen production rate, obtained industrial-level current density (e.g. 390 mA cm−2, 0.6V), and achieved economic viability ($2.51/kg of H2). These achievements benefit from a thermodynamically favorable hydrogen production pathway from aldehyde, facile kinetics on porous Cu-based catalysts, efficient mass transport in flow cells, and inexpensive size-exclusive separators. The successful implementation of such an energy-efficient process will impact future low-carbon hydrogen production and distributed chemical manufacturing.

Effects of management on the content and spectral characteristics of soil dissolved organic carbon in a subtropical forest

The differences of artificial measures, such as logging residue management, between assisted natural regeneration and afforestation may change the content and structure of soil dissolved organic carbon (DOC) and affect forest carbon cycle. In this study, we investigated the effects of managements on the content and spectral characteristics of DOC in a subtropical forest, which contained the forest of assisted natural regeneration (Ⅱ), and the plantation (Ⅲ), both were converted from mature secondary forests (Ⅰ). Results showed that DOC content in the 0-10 cm soil layer was significantly decreased by 21% and 50% in Ⅱ and Ⅲ, respectively, compared with that in Ⅰ. The DOC/SOC (soil organic carbon) ratios of 0-10 cm and 10-20 cm soil layers were significantly decreased by 27% and 43% after the conversion, respectively. In the 0-10 cm soil layer, the aromatic index and humification index of DOC in Ⅱ were significantly higher than that in Ⅲ. The infrared absorption ratio of soil DOC in the range of 3700-3000 cm-1, 1650-1620 cm-1, 1160-1000 cm-1, and 690-530 cm-1 in Ⅱ was higher than that in Ⅲ, indicating that the DOC in Ⅱ had higher carboxylic acids and aromatic substances than Ⅲ. The fluorescence index of DOC in Ⅱ and Ⅲ ranged from 1.4 to 1.9, and the biological index of Ⅱ was significantly higher than that of Ⅲ, indicating that Ⅲ had higher protein components in DOC and being more bioavailable. Thus, the differences of the content and structure of DOC between Ⅱ and Ⅲ might cause higher soil carbon pool of Ⅱ than that of Ⅲ.

OPTIMIZATION OF BIRD CHERRY OIL SUPERCRITICAL FLUID EXTRACTION PROCESS

Cherry cake berries, which is a waste of liquor production, contain biologically active substances, including lipids, which are not extracted by ethanol in the main production. Supercritical carbon dioxide is a good extractant for such compounds. By method of full factor experiment using rotatable uniform-plan of the second order, process of optimization of extraction of cherry oil from processed berries by method of supercritical fluid extraction with carbon dioxide was carried out. During planning, the pressure of 250 atm, temperature of 60 °C, hydraulic module 25 are selected as the main levels. To increase the accuracy of optimization, additional coefficients are sequentially included based on the Fisher test not increasing. Analysis of the regression equation made it possible to establish optimal process parameters: temperature 70 °C, pressure 350 atm, hydraulic module 33 at oil yield 1.4% (extraction degree 85%). The relative model error was 1%. Acid, iodine, ether numbers, saponification number, as well as organoleptic indices are determined for the obtained product. The obtained product is enriched with triacylglycerides, free fatty acids and low-molecular organic acids and contains a small amount of unsaturated higher carboxylic acids compared to oil isolated by extraction in a Soxlet apparatus with hexane.

Carboxylic acids in the flowers of Veronica spicata L. and Veronica incana L.

In the Ukrainian flora, species of Veronica L. genus (Plantaginaceae Juss.) are classified into 8 sections. Among the representatives of Pseudolysimachion W. D. J. Koch section in the Kharkiv region, Veronica spicata L. (spike speedwell) and Veronica incana L. (Veronica spicata L. subsp. incana (L.) Walters, silver speedwell) are common. Plants are used for the treatment of upper respiratory tract diseases, malignant neoplasms, gastrointestinal tract and genitourinary system disorders, diabetes mellitus.&#x0D; The aim of the research was to study the carboxylic acids of flowers of Veronica spicata L. and Veronica incana L.&#x0D; Materials and methods. The objects of the research were flowers of Veronica spicata L. and Veronica incana L., collected in the flowering stage in the Botanical Garden of Karazin University (Kharkiv, Ukraine) in summer 2018. The study of carboxylic acid composition was performed by chromatography-mass spectrometry on a 6890N MSD/DS Agilent Technologies chromatograph with a 5973N mass spectrometric detector. Identification of methyl esters of acids was performed using data from the mass spectrum libraries NIST 05 and Willey 2007 in a combination with programs for the identification of AMDIS and NIST; also, their retention time and the retention times of standard compounds were compared.&#x0D; Results. In Veronica incana L. flowers, 37 carboxylic acids were identified and quantified, constituting 1.05 %. In Veronica spicata L. flowers, 32 carboxylic acids were identified and quantified, the total content of which was 2.75 %.&#x0D; Conclusions. A higher carboxylic acid content was established in the flowers of Veronica spicata L. The fatty acid composition of Veronica incana L. flowers is characterized by a comparable content of saturated and unsaturated acids, while in Veronica spicata L. flowers, unsaturated fatty acids prevail over saturated fatty acids. The content of aromatic acids in the flowers of studied species was comparable. The characteristic carboxylic acids in the flowers of Veronica incana L. are oxalic, 3-hydroxy-2-methylglutaric, pentadecanoic, heneicosanoic, tricosanic,4-hydroxybenzoic, 4-methoxybenzoic and 3,4-dimethoxybenzoic acids; in the flowers of Veronica spicata L. – 2-hydroxy-3-methylglutaric, α-furanic and homovanillic acids

OBTAINING NON-GLYCERIDE OILS BY ETHERIFICATION OF GLUCOSE AND FRUCTOSE WITH CARBONIC ACIDS

Lipids are natural substances, mostly esters of glycerol with various fatty acids. They are found predominantly in animal products (butter, cheese and meat) and are present in vegetable oils. Natural fats play an important functional role for normal growth, development and maintenance of human health. Fat is a high-calorie food: it contains 9 kcal/g, compared to 4 kcal/g for proteins and carbohydrates. Adequate lipid intake is in the range of 5% to 10% of total energy intake. Excess consumption of fats and oils (20% or more) or disorders of fat and oil metabolism can be the source of various diseases, of which obesity is the most common. In addition, diseases such as coronary heart disease, stroke, diabetes, cancer, and others are associated with nutrition. For example, in the United States, various low-calorie oil substitutes have been developed, and approved for use by the GRAS FDA to optimize the caloric content of nutrition. Oil and fat substitutes such as Caprenin, Benefat, Bohenin, Captrin and others, with a calorific value of 4…5 kcal/g, are esters of glycerol with medium or short chain fatty acids. Fat substitutes have now become an important part of the American diet, however, as medical statistics shows, the problem of obesity is still far from being solved. We propose a new way – a full or partial replacement of edible oils (triglycerides) by oil-like substances with close physicochemical and culinary properties. In a series of studies, it was shown that if edible fatty acids are esterified with polyhydric alcohols (except glycerol), substances structurally related to fats and oils can be obtained, which can be characterized as non-glyceride fats and oils. But, unlike triglycerides, these new substances will have dietary properties as food ballast, since polyol esters are split with difficulty or not split at all by the digestive system. This paper presents the results of new studies on the synthesis of new non-glyceride fats and oils by esterification of glucose and fructose with higher carboxylic acids. Physical and chemical studies of the obtained products are carried out. Optimal methods for conducting reactions have been developed.

Cationic dyes and their use for the quantitative extraction-photometric determination of higher carboxylic acids

Cationic dyes of various natures have been investigated in order to select a dye that is stable under strongly alkaline conditions and applicable for the quantitative extraction-photometric determination of higher carboxylic acids. The nature of the dye, solvent, the length of the hydrocarbon radical of carboxylic acids and the pH of the aqueous phase for the extraction of ionic associates of higher carboxylic acids with cationic dye with pyronin G were experimentally studied. The study substantiates the practical application of the cationic dye pyronin G as an effective reagent for the quantitative extraction-photometric determination of higher carboxylic acids.

Extraction of yttrium

The demand for yttrium and other rare metals in many branches of technology, as well as in the chemical industry, is growing every year. The Republic of Kazakhstan possesses raw material sources of rare earths of the yttrium group. The improvement of technologies for the extraction and processing of rare earths is necessary to meet the needs of the industry for its own raw materials and, therefore, for the development of high-tech industries. To extract yttrium, an extraction method was used in this work. Organic reagents and their mixtures with low-melting organic compounds were tested as extractants. According to the results of the study, a mixture of D2EHPA-HCA(di-(2-ethylhexyl) phosphoric acid and higher carboxylic acids) was chosen as an effective extractant providing the quantitative extraction of yttrium. The extraction patterns of yttrium extraction by this extractant were studied depending on various factors (рН, Vw:Vorg, Сex, CMe, t°C). The yttrium content after extraction was determined in the aqueous phase by the photometric method with the arsenazo I reagent. The content in the organic phase was determined by calculation. In an acidic environment, the yttrium recovery rate was 97,45%. In this case, the optimal conditions for the extraction were as follows: pH = 3.0, the volumetric ratio of the aqueous and organic phases 1:10, the concentration of D2EHPA in the extractant 10%, the initial concentration of yttrium CMe = 10-4M, the temperature of the extraction 40-60°C. The results obtained show the efficiency of yttrium extraction from solutions obtained after dissolving yttrium-containing ores with the extractant D2EHPA-HCA.

Recent advances in homogeneous photocatalytic carboxylation incorporated with CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;

<p indent="0mm">Carbon dioxide (CO₂) has the advantages of low price, non-toxic, abundant and renewable. As CO₂ is an indispensable part of natural photosynthesis, it seems feasible to achieve artificial CO₂ fixation with the aid of light. For light-driven utilization of CO₂, two major categories can be diversified: (1) Photoreduction of CO₂ into other C1 resources, such as carbon monoxide, methanol, formic acid, and methane; (2) photocarboxylation, which is a green and sustainable method of fixing CO₂ into organic molecules. Therefore, taking CO₂ as a C1 synthon to participate in the reaction is an effective means to utilize it. Carrying out carboxylation reaction with CO₂ as raw material to produce acrylic acid, benzoic acid or other high value-added carboxylic acid derivatives has been a very important research significance. The carboxylation reactions using CO₂ usually include: (1) The use of strong nucleophiles such as Grignard reagents; (2) the use of stoichiometric metal reducing agents; (3) high temperature, high pressure and other conditions to activate the thermodynamic and dynamic stable CO₂. In the past decade, the homogeneous photocatalytic reaction has made a great progress. Researchers found photocatalytic organic reactions have many advantages, such as mild reaction conditions, high selectivity, and environmental protection. Compared to conventional thermal reaction system with CO₂ in the carboxylation reaction, the carboxylation reaction in photocatalysis has the following advantages: (1) Avoid the utilization of unstable strong reductant; (2) most of the reaction under mild conditions are performed; (3) during the reaction and post-processing to reduce the environmental impact. This article mainly introduces and summarizes the homogeneous carboxylation reactions involving photocatalytic CO₂ in recent years. At the same time, the study of mechanism is also an important part in the homogeneous photocatalytic reaction, especially in the field of the carboxylation reactions. The current photocatalytic carboxylation reaction can be roughly divided into three categories: (1) The electron transfer process occurs between the substrate and the photocatalyst, and the nucleophilic attack on the CO₂ molecule occurs after the formation of the corresponding anion intermediate to achieve carboxylation; (2) single electron transfer (SET) occurs between the CO₂ molecule and the photocatalyst, forming a CO₂ radical anion and then reaction with the substrates; (3) with assistant of the transition metal to form complex with the substrate and/or CO₂, a series of photocatalytic electron transfer processes and ligand transfer reactions to achieve the carboxylation. In addition, there is a carboxylation reaction realized by a synergistic [4+2] mechanism. Considering the importance of the study on the reaction mechanism in organic catalytic reactions, this article will focus on the employ the different types of intermediates generated in the reaction to achieve the homogeneous photocatalytic carboxylation of various substrates with CO₂, which include four types reaction mechanisms such as anionic intermediates, CO₂ radical anions, transition metal participation, and synergistic processes.

АНАЛИЗ СТРУКТУРЫ ПОЛОВЫХ ФЕРОМОНОВ И АТТРАКТАНТОВ ZYGAENIDAE (INSECTA, LEPIDOPTERA): БИОХИМИЧЕСКИЙ И ЭВОЛЮЦИОННЫЙ АСПЕКТЫ

In the review we analyse the data on the chemical composition and structure of all known sex pheromones and attractants of the Zygaenidae (Insecta, Lepidoptera). An attempt was done to trace the possible ways of evolution of the attractive molecules and to reveal the structural characters that determine their biological activity. Currently, sex pheromones and sex attractants are known for two of the five Zygaenidae subfamilies. Sex attractants of Zygaeninae are esters of acetic acid and higher alcohols, while sex attractants of Procridinae are esters of 2-butanol and higher carboxylic acids. The hydrocarbon radicals of the known attractive molecules of the Zygaenidae contain an even number of carbon atoms (12, 14, 16) and usually one double bond. Species specificity of the chemical signal is connected not only with the qualitative but also with quantitative ratio of the components of pheromone/attractant mixture.

Upgrading sugarcane biorefineries: Acetate addition allows for conversion of fermented sugarcane molasses into high-value medium chain carboxylic acids

The aim of this study was to evaluate the role of acetate (C2) on n-butyric (C4) and n-caproic acid (C6) production, using fermented sugarcane molasses as a substrate. Inoculum sludge was acclimatized in a continuous upflow anaerobic sludge blanket reactor, where ethanol (EtOH) and acetate (C2) were administered at a ratio of 6:1 (g COD:g COD). Organic load rate increased gradually from 2.0 g COD L−1d-1 to 3.3, and 5.0 g COD L−1d−1, for 157 days. The acclimatized sludge was used as the inoculum in six batch assays fed with fermented molasses (ethanol-rich source) and C2 at EtOH:C2 ratios, g COD:g COD of 2:1; 4:1; 6:1, 8:1, and 10:1. A control assay was performed without C2 (WA). The EtOH:C2 ratio was more favorable toward C6 production with a ratio of 10:1, in which a C6 yield was observed as well as accumulated production of 0.4 g COD g COD−1 and 7.9 g COD L−1, respectively. Conversely, the EtOH:C2 ratio of 2:1, and the WA, resulted in C6 concentrations of 1.4 g COD L−1 and 4.3 g COD L−1, respectively. These findings confirmed that substrate composition control is essential for driving fermentation processes toward high medium-chain carboxylic acid conversion rate.

ПРИМЕНЕНИЕ СОЛЕЙ d-МЕТАЛЛОВ 4-го ПЕРИОДА В КАЧЕСТВЕ КОАГУЛЯНТОВ В ТЕХНОЛОГИИ ПРОИЗВОДСТВА ЭМУЛЬСИОННЫХ КАУЧУКОВ

Currently, much attention is paid to improving the technology of rubbers obtained by emulsion polymerization. The stage of isolation of rubber from latex is one of the problematic stages of this production. The development of more advanced coagulating systems remains relevant. For the first time, the possibility of using d-metal salts of the fourth period of the periodic table of Mendeleev’s salts as coagulants in rubber isolation is considered: chloride of zinc, nickel and cobalt. The influence of the consumption of these salts on the completeness of rubber isolation is investigated, the properties of rubbers are estimated. It is found that zinc chloride has the best coagulating ability. The formation of insoluble complex compounds between the coagulating agent and surfactants of the latex system is established. It is revealed that the acidification of the coagulating system leads to the release of higher carboxylic acids in free form and the formation of sulfuric salts of zinc, cobalt and nickel, which remain in the aqueous phase (serum). The presence of these salts in the serum allows its usage in the technological process of emulsion rubbers production for the preparation of aqueous solutions of chlorides of these salts, as well as acidifying agent (sulfuric acid). The positive outcome of the considered issues contributes to the solution of a number of environmental problems. The studied rubber mixtures and vulcanizates prepared on the basis of experimental rubbers meet the regulatory requirements.

Камерная защита стали солями высших карбоновых кислот и Полиамина

Новые технологии, Химическая промышленность, Химическая технология, Научные журналы, Защита от коррозии, Технология металлов, Свойства материалов, Технические журналы, Наука и технологии, Справочная литература, Научные разработки

Feasibility Study for Using Jet Fuel in Diesel Engines

We have determined the primary jet fuel performance properties that have the greatest impact on how effectively they can be used in diesel engines, requiring improvement with the help of functional additives. We have studied the effect of a cetane improver additive based on 2-ethylhexyl nitrate and an antiwear additive based on higher carboxylic acids on the performance properties of jet fuels when they are used in diesel engines, and we have optimized their composition. We present the results of a study of the proposed fuel compositions based on jet fuel and functional additives, using laboratory and qualification methods and indicator properties for the D-245.125 engine cycle.

Green Rust: The Simple Organizing 'Seed' of All Life?

Korenaga and coworkers presented evidence to suggest that the Earth’s mantle was dry and water filled the ocean to twice its present volume 4.3 billion years ago. Carbon dioxide was constantly exhaled during the mafic to ultramafic volcanic activity associated with magmatic plumes that produced the thick, dense, and relatively stable oceanic crust. In that setting, two distinct and major types of sub-marine hydrothermal vents were active: ~400 °C acidic springs, whose effluents bore vast quantities of iron into the ocean, and ~120 °C, highly alkaline, and reduced vents exhaling from the cooler, serpentinizing crust some distance from the heads of the plumes. When encountering the alkaline effluents, the iron from the plume head vents precipitated out, forming mounds likely surrounded by voluminous exhalative deposits similar to the banded iron formations known from the Archean. These mounds and the surrounding sediments, comprised micro or nano-crysts of the variable valence FeII/FeIII oxyhydroxide known as green rust. The precipitation of green rust, along with subsidiary iron sulfides and minor concentrations of nickel, cobalt, and molybdenum in the environment at the alkaline springs, may have established both the key bio-syntonic disequilibria and the means to properly make use of them—the elements needed to effect the essential inanimate-to-animate transitions that launched life. Specifically, in the submarine alkaline vent model for the emergence of life, it is first suggested that the redox-flexible green rust micro- and nano-crysts spontaneously precipitated to form barriers to the complete mixing of carbonic ocean and alkaline hydrothermal fluids. These barriers created and maintained steep ionic disequilibria. Second, the hydrous interlayers of green rust acted as engines that were powered by those ionic disequilibria and drove essential endergonic reactions. There, aided by sulfides and trace elements acting as catalytic promoters and electron transfer agents, nitrate could be reduced to ammonia and carbon dioxide to formate, while methane may have been oxidized to methyl and formyl groups. Acetate and higher carboxylic acids could then have been produced from these C1 molecules and aminated to amino acids, and thence oligomerized to offer peptide nests to phosphate and iron sulfides, and secreted to form primitive amyloid-bounded structures, leading conceivably to protocells.

Chemical Composition and Properties of the Liquid-Vapor Interface of Aqueous C1 to C4 Monofunctional Acid and Alcohol Solutions.

The liquid-vapor interface is playing an important role in aerosol and cloud chemistry in cloud droplet activation by aerosol particles and potentially also in ice nucleation. We have employed the surface sensitive and chemically selective X-ray photoelectron spectroscopy (XPS) technique to examine the liquid-vapor interface for mixtures of water and small alcohols or small carboxylic acids (C1 to C4), abundant chemicals in the atmosphere in concentration ranges relevant for cloud chemistry or aerosol particles at the point of activation into a cloud droplet. A linear correlation was found between the headgroup carbon 1s core-level signal intensity and the surface excess derived from literature surface tension data with the offset being explained by the bulk contribution to the photoemission signal. The relative interfacial enhancement of the carboxylic acids over the carboxylates at the same bulk concentration was found to be highest (nearly 20) for propionic acid/propionate and still about 5 for formic acid/formate, also in fair agreement with surface tension measurements. This provides direct spectroscopic evidence for high carboxylic acid concentrations at aqueous solution-air interfaces that may be responsible for acid catalyzed chemistry under moderately acidic conditions with respect to their bulk aqueous phase acidity constant. By assessing the ratio of aliphatic to headgroup C 1s signal intensities XPS also provides information about the orientation of the molecules. The results indicate an increasing orientation of alcohols and neutral acids toward the surface normal as a function of chain length, along with increasing importance of lateral hydrophobic interactions at higher surface coverage. In turn, the carboxylate ions exhibit stronger orientation toward the surface normal than the corresponding neutral acids, likely caused by the stronger hydration of the charged headgroup.

Biotechnology is storming the heights of petrochemistry

This brief review deals with the most important recent achievements of industrial biotechnology in its competition with petrochemistry: creation of the bioethanol industry; discovery of the fermentation of CO-containing gases, a new way of converting biomass into chemicals; carrying out the fermentation of С5 and С6 carbohydrates at similar rates; development of new methods of producing divinyl, isoprene, nylon, butanol, higher straight-chain alcohols, isopropanol, isobutanol, 1,4-butanediol, 2,3-butanediol, and succinic acid; progress in the culturing and processing of microalgae, an important source of glycerol and higher carboxylic acids.

Aqueous synthesis of CuInZnS/ZnS quantum dots by using dual stabilizers: A targeting nanoprobe for cell imaging

Herein, we prepared dual-stabilizer-capped CuInZnS/ZnS (CIZS/ZnS) quantum dots (QDs) in aqueous media via hydrothermal routes. On using the combination of poly (styrenesulfonic acid-co maleic acid) and glutathione stabilizers, we found that dual stabilizers effectively coat the surface of CIZS/ZnS QDs, resulting in high quantum yields and carboxylic acid groups that conjugate with various materials. To demonstrate their potential biomedical application, the dual-stabilizer-capped CIZS/ZnS QDs were conjugated with 3-aminophenylboronic acid, termed CIZS/ZnS@APBA, for HeLa tumor cell labeling. In vitro and in vivo assessments using HeLa cells and zebrafish embryos, respectively, revealed that these CIZS/ZnS@APBA nanoprobes exhibit low cytotoxicity under our experimental conditions. Confocal scanning laser imaging demonstrated that the nanoprobes can be efficiently internalized and are localized in the cytoplasm of HeLa cells. This work reveals the potential for use of CIZS/ZnS@APBA as a safe and effective targeted probe for in vivo imaging of cancer.