使用萃取蒸馏塔生产无水乙醇的过程

正本发明涉及到从醋酸加氢反应得到的粗乙醇产品回收乙醇。应用的粗乙醇产品的分离和净化过程能够回收无水乙醇成分。过程包括使用一台或多台萃取蒸馏塔分离粗乙醇产品,萃取蒸馏塔应用一种或多种萃取剂。以无水乙醇成分的总质量计,无水乙醇成分包     

在恒温反应器中生产乙醇的过程

正本发明涉及到生产乙醇的过程。过程包括反应步骤,即在催化剂存在和合适反应条件下醋酸和氢在壳-管反应器中有效形成粗乙醇产品。粗乙醇产品包含乙醇,醋酸,醋酸乙酯和水。过程还包括从粗乙醇产品回收乙醇的步骤。壳-管反应器包含一根管子或多根管子,每根管子装有热     

The effects of solvent polarity and pKa on the absorption of solvents into poly(glutaric acid‐glycerol) films

In this study, solvent absorption into the matrices of poly(glutaric acid‐glycerol) films has been evaluated. It was determined that the combined effects of polarity and the size and shape of the solvent molecule, rather than pKa, have the most significant influence on absorption into the films. Polar aprotic solvents (with solvent polarity index values >4) such as 1,4‐dioxane (absorbed 163.8% ± 0.3% [w/w] of the original weight of the polymer), pyridine (200.4% ± 3.5%), and dimethyl sulfoxide (186.0% ± 11.4%) were among the highest absorbed solvents into the polymer matrix. Solvents with polarity index values ≤4.0 were absorbed poorly (≤5.3% ± 1.5%). The polymer films only absorbed ≤26.5% ± 2.1% of their weight of most protic solvents (water and mono‐alcohols) but absorbed 72.6% ± 6.5% of ethylene glycol, a diol. The only high absorbing polar protic solvent was acetic acid (131% ± 13.1%). Except for chloroform, ethyl acetate, and ethanol, all of the solvents examined displayed small increases in absorption (7.8%, on average) when the films were desorbed and used again to absorb solvent. Erosion of the films ranged from 0.0% ± 0.0% to 22.0% ± 3.2% after 2–10 h absorption cycles. Miscible (7.7% ± 2.3% to 15.1% ± 2.2%) and immiscible (12.3% ± 6.4% to 80.0% ± 1.9%) solvents were preferentially absorbed from aqueous solutions. However, up to approximately 5% of those absorption values could be from water absorption. © 2014 Wiley Periodicals, Inc.^? J. Appl. Polym. Sci. 2014 , 131, 40434.     

Evolution of the properties of a poly(l‐lactic acid) scaffold with double porosity during in vitro degradation in a phosphate‐buffered saline solution

A poly(l ‐lactic acid) scaffold prepared by a combination of freeze‐extraction and porogen‐leaching methods was submitted to static degradation in a phosphate‐buffered saline solution at pH 7.4 and 37°C for up to 12 months. After 6 months of degradation, the scaffold maintained its integrity, although noticeable changes in its permeability and pore size were recorded. After 12 months, scanning electron microscopy pictures showed that most of the trabeculae were broken, and the sample disaggregated under minimum loading. Neither weight loss nor crystallinity changes in the first heating calorimetric scan were observed during the degradation experiment. However, after 12 months, a rise in the crystallinity from 13 to 38% and a drop in the glass‐transition temperature from 58 to 54°C were measured in the second heating scan. The onset of thermal degradation moved from 300 to 210°C after 12 months. Although the elastic modulus suffered only a very slight reduction with degradation time, the aggregate modulus decreased 44% after 6 months. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40956.     

Treat Me Well or Will Resist: Uptake of Mobile Genetic Elements Determine the Resistome of Corynebacterium striatum

Corynebacterium striatum, a bacterium that is part of the normal skin microbiota, is also an opportunistic pathogen. In recent years, reports of infections and in-hospital and nosocomial outbreaks caused by antimicrobial multidrug-resistant C. striatum strains have been increasing worldwide. However, there are no studies about the genomic determinants related to antimicrobial resistance in C. striatum. This review updates global information related to antimicrobial resistance found in C. striatum and highlights the essential genomic aspects in its persistence and dissemination. The resistome of C. striatum comprises chromosomal and acquired elements. Resistance to fluoroquinolones and daptomycin are due to mutations in chromosomal genes. Conversely, resistance to macrolides, tetracyclines, phenicols, beta-lactams, and aminoglycosides are associated with mobile genomic elements such as plasmids and transposons. The presence and diversity of insertion sequences suggest an essential role in the expression of antimicrobial resistance genes (ARGs) in genomic rearrangements and their potential to transfer these elements to other pathogens. The present study underlines that the resistome of C. striatum is dynamic; it is in evident expansion and could be acting as a reservoir for ARGs.     

Solar performance of hemispherical vault roofs

In hot climates, the improvement of comfort by passive solar techniques is a very important issue. In many parts of the world such as the Middle East, vault roofs are widely used in construction. The solar and energy performance of a hemispherical vault roof is studied, including the auto-shading instant effect during several days for different latitudes and throughout the year also. The results are compared with the standard horizontal flat roofing used in the typical modern low-cost housing in Mexico. The hemispherical vault receives around 35% less energy than the flat roof between the equinoxes, besides having other advantages such as a greater ceiling height, natural ventilation and illumination possibilities, and structural stability.     

Glass‐transition and gas‐transport characteristics of polymer nanocomposites based on crosslinked poly(ethylene oxide)

The glass‐transition and gas‐transport properties of rubbery polymer nanocomposites based on crosslinked poly(ethylene oxide) and metal oxide nanoparticles were studied. Nanocomposite samples were prepared by the UV photopolymerization of poly(ethylene glycol) diacrylate (n ～ 14) in the presence of magnesium oxide or silica nanoparticles. The thermomechanical properties of the composites were investigated with dynamic mechanical and dielectric spectroscopy methods. The inclusion of nanoparticles in the crosslinked poly(ethylene glycol) diacrylate network led to a systematic increase in rubbery modulus and a modest positive offset (～6°C) in the measured glass‐transition temperature for both systems. Bulk density measurements indicated only minimal void volume fraction in the composites, and CO₂ and light gas permeability decreased with particle loading; for example, the CO₂ infinite dilution permeability at 35°C decreased from 106 barrer in the unfilled polymer to 55 barrer in a nanocomposite containing 30 wt % magnesium oxide nanoparticles. The inclusion of toluene diluent in the prepolymerization mixtures produced a limited enhancement in sample permeability, but the sizeable increases in gas transport with particle loading reported for certain other rubbery nanocomposite systems were not realized in the crosslinked poly(ethylene glycol) diacrylate composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

The effect of chemistry on the polymerization, thermo-mechanical properties and degradation rate of poly(β-amino ester) networks

Poly(β-amino ester) networks are gaining attention as a scaffold material for tissue engineering applications where it is important to have tailorable degradation rate and elastic modulus. The objective of this work is to characterize and understand the relationships between chemical structure, polymerization, thermo-mechanical properties, and degradation in poly(β-amino esters) networks. The networks were synthesized from a primary amine with systematically varied molar ratios and chemical structures of diacrylates. Fundamental trends were established between the chemical structure, conversion during polymerization, macromer molecular weight, rubbery modulus, and degradation rate. The thermo-mechanical properties were dependent upon both polymerization steps. The rubbery modulus was tailorable over a range of several MPa by changing molar ratio and diacrylate molecular weight. The degradation rate ranged from hours to months depending upon the composition. Select chemical structures showed degradation rate independent of modulus. This work provides a basis for designing poly(β-amino esters) networks with specific thermo-mechanical properties and degradation rates for biomedical scaffolds.     

Bioactivity and emerging role of short and medium chain fatty acids

Cardiovascular disease (CVD) and insulin resistance are directly linked to overweight and obesity. Thus, any dietary strategy capable of causing weight reduction will lower CVD and diabetes risk. Oils rich in medium‐chain saturated fatty acids (MCFA) are among several dietary components that may have potential in the treatment of obesity. MCFA are less energy dense and highly ketogenic compared to long‐chain saturated and unsaturated fatty acids (LCFA). MCFA also differ from LCFA in their digestive and metabolic pathways, since they are easily oxidized and utilized as energy, with little tendency to deposit as body fat. The dietary intake of short (SCFA) and medium‐chain saturated fatty acids from natural food sources is approximately 2.4 g/day and accounts for about 9% of the total saturated fatty acid (SFA) intake. Although early clinical studies with high levels of MCFA resulted in increased levels of plasma triacylglycerols (TAG) and low‐density lipoprotein cholesterol (LDL‐C), and reduced levels of high‐density lipoprotein cholesterol (HDL‐C) compared to diets enriched in unsaturated LCFA, these adverse effects have not been observed in more recent studies with smaller more realistic amounts of MCFA. The lower caloric value of SCFA and MCFA and their unique metabolic features form the basis for their clinical use in enteral and parenteral nutrition and for novel reduced calorie lipids for use in conventional food products.     

A catalytic reactor for the trapping of free radicals from gas phase oxidation reactions

A catalytic reactor for the trapping of free radicals originating from gas phase catalytic reactions is described and discussed. Radical trapping and identification were initially carried out using a known radical generator such as dicumyl peroxide. The trapping of radicals was further demonstrated by investigating genuine radical oxidation processes, e.g., benzaldehyde oxidation over manganese and cobalt salts. The efficiency of the reactor was finally proven by the partial oxidation of cyclohexane over MoO(3), Cr(2)O(3), and WO(3), which allowed the identification of all the radical intermediates responsible for the formation of the products cyclohexanol and cyclohexanone. Assignment of the trapped radicals was carried out using spin trapping technique and X-band electron paramagnetic resonance spectroscopy.