Experimental Measurement and Correlation of the Solubility of Methyl-acetyl-naphthalene in n-Heptane,n-Octane,and n-Dodecane

1 INTRODUCTION 2-Methyl-6-acetylnaphthalene (2,6-MAN) is a type of white or pale yellow, powdery crystal, with a melting point of 332.15K. It is an important interme- diate[1] used for producing 2,6-naphthalene dicarbox- ylic acid (2,6-NDA), which has very extensive appli- cations in not only the light, electronic, and defense industries, but in many other areas. In particular, 2,6-NDA is an important monomer of liquid crystal polyester material (LCP) and polyethylene naphtha- lene-2…     

Effects of Zn, Cu, and K Promoters on the Structure and on the Reduction, Carburization, and Catalytic Behavior of Iron-Based Fischer–Tropsch Synthesis Catalysts

Zn, K, and Cu effects on the structure and surface area and on the reduction, carburization, and catalytic behavior of Fe–Zn and Fe oxides used as precursors to Fischer–Tropsch synthesis (FTS) catalysts, were examined using X-ray diffraction, kinetic studies of their reactions with H₂ or CO, and FTS reaction rate measurements. Fe₂O₃ precursors initially reduce to Fe₃O₄ and then to metallic Fe (in H₂) or to a mixture of Fe_2.5C and Fe₃C (in CO). Zn, present as ZnFe₂O₄, increases the surface area of precipitated oxide precursors by inhibiting sintering during thermal treatment and during activation in H₂/CO reactant mixtures, leading to higher FTS rates than on ZnO-free precursors. ZnFe₂O₄ species do not reduce to active FTS structures, but lead instead to the loss of active components; as a result, maximum FTS rates are achieved at intermediate Zn/Fe atomic ratios. Cu increases the rate of Fe₂O₃ reduction to Fe₃O₄ by providing H₂ dissociation sites. Potassium increases CO activation rates and increases the rate of carburization of Fe₃O₄. In this manner, Cu and K promote the nucleation of oxygen-deficient FeO _x species involved as intermediate inorganic structures in reduction and carburization of Fe₂O₃ and decrease the ultimate size of the Fe oxide and carbide structures formed during activation in synthesis gas. As a result, Cu and K increase FTS rates on catalysts formed from Fe–Zn oxide precursors. Cu increases CH₄ and the paraffin content in FTS products, but the additional presence of K inhibits these effects. Potassium titrates residual acid and hydrogenation sites and increases the olefin content and molecular weight of FTS products. K increases the rate of secondary water–gas shift reactions, while Cu increases the relative rate of oxygen removal as CO₂ instead of water after CO is dissociated in FTS elementary steps. Through these two different mechanisms, K and Cu both increase CO₂ selectivities during FTS reactions on catalysts based on Fe–Zn oxide precursors.     

The role of the symmetry and the flexibility of the anion on the characteristics of the nanostructures and the viscosities of ionic liquids☆

The transport properties of ionic liquids (ILs) are crucial properties in view of their applications in electrochem-ical devices. One of the most important advantages of ILs is that their chemical–physical properties and conse-quently their bulk performances can be well tuned by optimizing the chemical structures of their ions. This will require elucidating the structural features of the ions that fundamentally determine the characteristics of the nanostructures and the viscosities of ILs. Here we showed for the first time that the“rigidity”, the order, and the compactness of the three-dimensional ionic networks generated by the anions and the cation head groups determine the formation and the sizes of the nanostructures in the apolar domains of ILs. We also found that the properties of ionic networks are governed by the conformational flexibility and the symmetry of the anion and/or the cation head group. The thermal stability of the nanostructures of ILs was shown to be con-trolled by the sensitivity of the conformational equilibrium of the anion to the change of temperature. We showed that the viscosity of ILs is strongly related to the symmetry and the flexibility of the constitute ions rather than to the size of the nanostructures of ILs. Therefore, the characteristics of the nanostructures and the viscosities of ILs, especially the thermal stability of the nanostructures, can be fine-tuned by tailoring the symmetry and the conformational flexibility of the anion.     

Physicochemical,adsorption, and catalytic properties of high-silica zeolites of the MFI type in the conversion of the propane–butane fraction into aromatic hydrocarbons

The complex of physicochemical properties of high-silica zeolites of the MFI-type obtained using organic templates, including hexamethylenediamine, POD-oils, and pentaerythritol, has been investigated. It was shown that zeolites produced using different templates demonstrated different activity and selectivity in the process of converting the propane–butane fraction into aromatic hydrocarbons.     

On the results of the First All-Russian Conference “Sol-Gel Synthesis and Study of Inorganic Compounds,Hybrid Functional Materials,and Disperse Systems”

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On the results of the First All-Russian Conference “Sol-Gel Synthesis and Study of Inorganic Compounds, Hybrid Functional Materials, and Disperse Systems”     

Supported Ziegler type catalysts for production of polyethylene (PE): Effect of the composition of the active component,the methods of its formation,and the use of modifying agents on catalytic activity and molecular structure of PE and copolymers of ethylene with α-olefins

Summarized results are presented from studying the formation of the active component of supported Ziegler type catalysts, investigating the effect of the composition of these catalysts on the molecular mass characteristics of PE, and seeking new methods for producing catalysts with optimum morphology.     

Fatty Acid Composition of the Maternal Diet During the First or the Second Half of Gestation Influences the Fatty Acid Composition of Sows’ Milk and Plasma,and Plasma of Their Piglets

Dietary supplements of olive oil (OO) or fish oil (FO) during the first (G1: day 1–60) or second half of gestation (G2: day 60 to term, day 115) were offered to pregnant sows. The proportion of fatty acids in milk and plasma were determined by gas chromatography. When supplements were given during G1, the proportions of oleic acid (OA) and arachidonic acid (AA) in the plasma were higher in the OO group than in the FO group, whereas docosahexaenoic acid (DHA) was higher in the latter group at day 56 of gestation. These differences in plasma DHA were still apparent at day 7 of lactation. Similarly, DHA was also higher in the colostrum and milk on days 3 and 21 of lactation and in the plasma of piglets from FO dams compared to the OO group, whereas AA was lower. When the FO supplement was given during G2, AA was lower and DHA higher in the plasma at day 105 of gestation and at day 7 of lactation compared with the OO group. Likewise, DHA was greater in FO than in OO animals during lactation in colostrum and in milk on days 3 and 21 of lactation, and in 3-day old suckling piglets plasma, whereas AA was lower in these animals. Thus, maternal adipose tissue plays an important role in the storage of dietary long-chain polyunsaturated fatty acids (LCPUFA) during G1. They are mobilized around parturition for milk synthesis, and an excess of dietary n-3 LCPUFA decreases the availability of AA in suckling newborns.     

Uncertainty Budget of the SMPS–APS System in the Measurement of PM1, PM2.5, and PM10

The effects of particulate matter on environment and public health have been widely studied in recent years. In spite of the presence of numerous studies about this topic there is no agreement on the relative importance of the particles' size and origin with respect to health effects among researchers. Nevertheless, air quality standards are moving, as the epidemiological attention, towards greater focus on the smaller particles. The most reliable method used in measuring particulate matter (PM) is the gravimetric method since it directly measures PM concentration, guaranteeing an effective traceability to international standards. This technique, however, neglects the possibility to correlate short term intraday atmospheric parameter variations that can influence ambient particle concentration and size distribution as well as human activity patterns. Besides, a continuous method to determine PM concentrations through the measurement of the number size distribution is the system constituted by a Scanning Mobility Particle Sizer (SMPS) and an Aerodynamic Particle Sizer (APS). In this article, the evaluation of the uncertainty budget in measuring PM through the SMPS–APS system, as well as a metrological comparison with the gravimetric reference method in order to analyze the compatibility, was carried out and applied with reference to an experimental campaign developed in a rural site. This choice allowed to assume the hypothesis of spherical particle morphology. The average PM₁₀, PM_2.5, and PM₁ uncertainties obtained for the SMPS–APS system are equal to 27%, 29%, and 31%, respectively. Here the principle influence parameter is the particle density that has to be directly measured with low uncertainty in order to reduce the PM uncertainty.     

Accumulation and apparent recovery of N,P and K after the incorporation of gliricidia and manure in intercropping during the cultivation of corn–cowpea–cotton

Fertilization with manure is widely adopted by farmers in the semiarid region of northeastern Brazil, although the quantity of available manure is limited. Thus, among other alternatives, gliricidia has been used as an additional source of organic fertilizer. The objective of this study was to evaluate the accumulation and apparent recovery of N, P and K after using different forms of gliricidia and manure application in the intercropping of corn, cowpea and cotton in three crop cycles in the semi-arid northeast region of Brazil. The following treatments were used: gliricidia incorporated into the soil before planting; gliricidia spread on the surface of the soil at 45 days after planting; manure and gliricidia incorporated into the soil before planting; manure incorporated into the soil before planting and gliricidia spread on the surface of the soil at 45 days after planting; manure incorporated into the soil before planting; and no addition of organic fertilizer (control). Accumulations followed the same pattern as biomass production but differed greatly from the concentrations. Low apparent recoveries were obtained in the first and second cycles, and high apparent recoveries were obtained in the third cycle. The nutrient balances indicated that the incorporation of gliricidia before planting or spread on the surface does not meet crop needs. The incorporation of manure as well as manure and gliricidia when applied on the surface, were able to meet growth needs and maintain soil fertility.     

Effects of the initial α-SiC content on the microstructure, mechanical properties, and permeability of macroporous silicon carbide ceramics

By using α- and/or β-SiC staring powders, the effects of the initial α-phase content on the microstructure, mechanical properties, and permeability of macroporous SiC ceramics were investigated. When β-SiC powder or a mixture of α/β powders containing a small amount (≤10%) of α-SiC powder was used, the microstructure consisted of large platelet grains. In contrast, when using α-SiC powder or α/β powders containing a large amount (>10%) of α powders, the microstructure consisted of small equiaxed grains. The development of large α-SiC platelet grains in the microstructure did not result in any improvement of the flexural strength of the macroporous SiC ceramics because of the accompanying pore growth and grain growth. The growth of the platelet-SiC grains was beneficial in increasing the gas permeability of the macroporous SiC ceramics from 4.12 × 10⁻¹³ m² for macroporous SiC with an equiaxed microstructure to 1.89 × 10⁻¹² m² for macroporous SiC ceramics with large platelet grains.     

Influence of solvent,Lewis acid–base complex,and nanoparticles on the morphology and gas separation properties of polysulfone membranes

A series of polysulfone (PSF) membranes were prepared using different solvents: dimethylformamide (DMF), tetrahydrofuran, dimethylacetamide, and n-methyl-2-pyrrolidone (NMP). The PSF membrane prepared by NMP showed the highest gas permeability. The influence of propionic acid as a Lewis acid on gas separation properties of the PSF was explored. The PSF membrane prepared by the casting solution containing 25 wt% PSF, 35 wt% propionic acid, and 40 wt% NMP showed a superior gas separation performance. The gas permeation measurements indicated that incorporating 30 wt% γ-alumina nanoparticles into the PSF matrix resulted in about the respective 43% and 41% increase in CO₂ and O₂ permeability together with a rise in CO₂/CH₄ and O₂/N₂ selectivities (13% and 7%, respectively). Furthermore, by rearranged modified Maxwell model, the role and nature of the interfacial layer in the PSF-based mixed matrix membranes were mathematically analyzed considering a reduced permeability factor.     

Effect of α-, β-, γ-, and δ-Tocotrienol on the Oxidative Stability of Lard

Despite the structural similarity of tocopherols, the antioxidative activities of tocotrienol homologues have not been studied often. In this study, the antioxidant activities of α-, β-, γ-, and δ-tocotrienols at various concentrations from 100 to 1,000 ppm in lard were evaluated. Headspace oxygen content of the lard without tocotrienol decreased from 21.1 to 10.7 % and the peroxide value increased from 0.4 to 33.4 mequiv/kg after 7 days of storage at 55 °C in the dark. α-Tocotrienol at 100 ppm and β-tocotrienol at 100 and 200 ppm effectively improved the oxidative stability of lard; however, the antioxidative activities of α- and β-tocotrienol reduced as the concentration increased to 1,000 ppm. The γ- and δ-tocotrienols improved the oxidation stability of lard and the effectiveness was essentially same at all concentrations (p > 0.05). The antioxidative activities of tocotrienols in the autoxidation of lard increased in the order of α-, β-, γ-, and δ-tocotrienols. The activities of tocotrienols in lard were different depending on the type of homologues and concentrations.     

General characteristics of Pinus spp. Seed fatty acid compositions, and importance of Δ5-olefinic acids in the taxonomy and phylogeny of the genus

The Δ5-unsaturated polymethylene-interrupted fatty acid (Δ5-UPIFA) contents and profiles of gymnosperm seeds are useful chemometric data for the taxonomy and phylogeny of that division, and these acids may also have some biomedical or nutritional applications. We recapitulate here all data available on pine (Pinus; the largest genus in the family Pinaceae) seed fatty acid (SFA) compositions, including 28 unpublished compositions. This overview encompasses 76 species, subspecies, and varieties, which is approximately one-half of all extant pines officially recognized at these taxon levels. Qualitatively, the SFA from all pine species analyzed so far are identical. The genus Pinus is coherently united—but this qualitative feature can be extended to the whole family Pinaceae—by the presence of Δ5-UPIFA with C₁₈ [taxoleic (5,9–18∶2) and pinolenic (5,9,12–18∶3) acids] and C₂₀ chains [5,11–20∶2, and sciadonic (5,11,14–20∶3) acids]. Not a single pine species was found so far with any of these acids missing. Linoleic acid is almost always, except in a few cases, the prominent SFA, in the range 40–60% of total fatty acids. The second habitual SFA is oleic acid, from 12 to 30%. Exceptions, however, occur, particularly in the Cembroides subsection, where oleic acid reaches ca. 45%, a value higher than that of linoleic acid. α-Linolenic acid, on the other hand, is a minor constituent of pine SFA, almost always less than 1%, but that would reach 2.7% in one species (P. merkusii). The sum of saturated acids [16∶0 (major) and 18∶0 (minor) acids principally] is most often less than 10% of total SFA, and anteiso-17∶0 acid is present in all species in amounts up to 0.3%. Regarding C₁₈ Δ5-UPIFA, taxoleic acid reaches a maximum of 4.5% of total SFA, whereas pinolenic acid varies from 0.1 to 25.3%. The very minor coniferonic (5,9,12,15–18∶4) acid is less than 0.2% in all species. The C₂₀ elongation product of pinolenic acid, bishomo-pinolenic (7,11,14–20∶3) acid, is a frequent though minor SFA constituent (maximum, 0.7%). When considering C₂₀ Δ5-UPIFA, a difference is noted between the subgenera Strobus and Pinus. In the former subgenus, 5,11–20∶2 and sciadonic acids are ≤0.3 and ≤1.9%, respectively, whereas in the latter subgenus, they are most often ≥0.3 and ≥2.0%, respectively. The highest values for 5,11–20∶2 and sciadonic acids are 0.5% (many species) and 7.0% (P. pinaster). The 5,11,14,17–20∶4 (juniperonic) acid is present occasionally in trace amounts. The highest level of total Δ5-UPIFA is 30–31% (P. sylvestris), and the lowest level is 0.6% (P. monophylla). Uniting as well as discriminating features that may complement the knowledge about the taxonomy and phylogeny of pines are emphasized.     

Synthesis and Characterization of the Inclusion Complex of β-cyclodextrin and Azomethine

A β-cyclodextrin (β-Cyd) inclusion complex containing azomethine as a guest was prepared by kneading method with aliquot addition of ethanol. The product was characterized by Fourier Transform Infrared (FTIR) spectrometer, ¹H Nuclear Magnetic Resonance (¹H NMR) and Thermogravimetric Analyzer (TGA), which proves the formation of the inclusion complex where the benzyl part of azomethine has been encapsulated by the hydrophobic cavity of β-Cyd. The interaction of β-Cyd and azomethine was also analyzed by means of spectrometry by UV-Vis spectrophotometer to determine the formation constant. The formation constant was calculated by using a modified Benesi-Hildebrand equation at 25 °C. The apparent formation constant obtained was 1.29 × 10⁴ L/mol. Besides that, the stoichiometry ratio was also determined to be 1:1 for the inclusion complex of β-Cyd with azomethine.     

Pseudokinetics for the copolymerization of butadiene and styrene produced using n-butyl lithium and N,N,N′,N′-tetramethylethylenediamine,considering different reactivities of the structural units

The anionic solution copolymerization of butadiene and styrene prepared by anionic living polymerization using an initiator composed of n-butyl lithium, and N,N,N′,N′-tetramethylethylenediamine as active center modifier was modeled as a tetrapolymerization. The kinetic model proposed considering that the reactivity of the active sites is different because of varying configurations cis, trans, vinyl, and styryl. From the reaction scheme expressions to rate of monomers consumption, microstructure and dyad formation were obtained. With the first-order Markov model, the expressions for the fraction of active sites and dyad distribution as a function of the conditional probabilities were obtained. Therefore, the model proposed is different to kinetic models previously reported, because it allows obtaining the parameters kinetic in order to know the distribution of the isomeric species presents in the copolymerization of butadiene and styrene, and the intrinsic reactivity of configurational active sites. The rate constants were determined by fitting to the conversion and dyad experimental data using the nonlinear least square method. The experimental data reported in the literature, monomer conversion and microstructure, in addition to dyad sequence distribution were correctly predicted.     

An in-Depth Analysis of the Swelling,Mechanical, Electrical,and Drug Release Properties of Agar–Gelatin Co-Hydrogels

Agar–gelatin-based co-hydrogels were prepared with different compositions of the agar and the gelatin fractions. The intermolecular hydrogen bonding was higher in the co-hydrogels as compared to the gelatin hydrogel. Swelling studies indicated diffusion-mediated swelling. The electrical stability of the co-hydrogels was higher as compared to the gelatin hydrogel. Though the firmness of the co-hydrogels was higher, Weichert model of viscoelasticity indicated that the inherent mechanical stability of the gelatin hydrogel was superior. The release of ciprofloxacin hydrochloride was predominately Fickian diffusion-mediated. In gist, the co-hydrogels can be tried as polymeric constructs for controlled drug delivery applications.     

The effect of processing conditions,amount of additives and composition on the microstructures and mechanical properties of α-SiAlON ceramics

A series of samples with yttrium α-SiAlON compositions and different amounts of additive has been fabricated from α-Si₃N₄, AlN, Al₂O₃ and Y₂O₃ starting powders, using gas pressure sintering and three different sintering procedures. One series of samples was heated up to 1825°C and then held for 3 h, another group of samples was held at a lower temperature (1500 or 1600°C) for 1 h and then heated up to 1825°C and held for 3 h. The results of investigations using scanning electron microscopy showed the effect of composition and sintering procedure on the morphology of α-SiAlON grains. It was found that the amount of elongated grains increased with increasing amount of liquid phase. The mechanical tests showed that all of the samples exhibited HV10 values in the range of 1800–1976 kg/mm and K_IC values in the range of 3.9–6.3 MPam^1/2.     

Diet and caloric sufficiency in the migrant indigenous population of the Altos Region of Chiapas, México

The population that has migrated from rural zones to urban areas is subject to changes in their dietary patterns and is considered a vulnerable population group in terms of food security. This article describes the diet of the immigrant indigenous population in the city of San Cristóbal de Las Casas, analyzing the factors that contribute to adequate calorie consumption in 143 families. This is a cross-sectional study based on a structured interview in which information was obtained related to socio-economic variables, the variety and types of foods in the home, and adequate calorie consumption per capita based on requirements according to age and sex. Using nonparametric statistical tests, the relationship between the population's income level and the number of calories available was determined. Results show a significant association between the income level of the population and the number of calories available in homes; however, there is not a significant association between the amount of time a family has lived in the city and the type and variety of foods available to and consumed by these families. Results show that 91.3% of these families ingest the suggested calorie consumption; the population with the lowest income levels represents a lower percentage of this indicator, and also showed significant deficiencies in proteins and nutrients such as calcium and vitamin A. The implications of rural-urban migration by indigenous populations in relation to diet quality are discussed.