A cost-effective high solids epoxy binder for protective coatings

Conclusion  From the foregoing it can be concluded that Epikote DX-874 can be used with a variety of curing agents for specific end-use requirements. A solids content of 85–90% by weight can be obtained by careful formulation of the paint. Performance equal to that of a traditional solvent-borne solid epoxy resin — polyamide curing agent binder system can be obtained when the incorporation of an aliphatic flexible part in the epoxy resin is compensated for by a part aromatic or cycloaliphatic component in the curing agent. By an example it is demonstrated that a lower cost can be obtained compared with that of traditional solvent-borne systems. Further cost savings in paint manufacturing, transport and application can be envisaged.     

Effect of momentum transport on conversion in adiabatic catalytic tubular reactors

Neglecting the effect of velocity change on conversion in a gaseous plug flow solid catalysed reactor can lead to an overestimation of conversion by a factor of 3 or underestimation of reactor size for a given conversion by factors of 2 or more in highly exothermic adiabatic cases. Diffusion control, reaction control, and combined domination of rate situations are considered. For many practical situations in monoliths at subsonic velocity the effects of friction and momentum convection on velocity change can be neglected. The direct relationship between velocity and gas temperature in these situations can be accurately derived by assuming isobaric flow. In packed bed reactors reducing particle size below critical limits can appreciably reduce conversion (with increased pressure drop) compared with values estimated by neglecting the effect of friction. An adaptive variable order finite difference method has operated successfully in all cases studied for values of solids Peclet number, Pe_s <200.     

Use of sweet sorghum juice for lactic acid fermentation: preliminary steps in a process optimization

BACKGROUND: Lactic acid has many applications in the chemical industries and it can be produced economically by microorganisms using biomass raw materials of different origins. Sweet sorghum juice is a high sugar content raw material with potential for lactic acid production because after hydrolysis of its sucrose content the remaining glucose and fructose can supply the carbon demand of most lactic acid bacteria. However, satisfying the nitrogen and B‐vitamin needs of the bacteria by supplementation with yeast extract and/or other alternative nitrogen‐containing supplements can make the process too expensive. RESULTS: Using a statistical optimization process much of the yeast extract can be replaced by a cheaper alternative nitrogen source, namely wheat gluten. This resulted in a fermentation with 99% lactic acid yield and 3.04 g L^?1 h^?1 volumetric productivity. CONCLUSION: Using response surface methodology (RSM) media optimization was performed for lactic acid fermentation with an industrially acceptable result, reducing the costs of raw materials by half, replacing yeast extract by an alternative nitrogen source and applying yeast extract only as a source of micro‐elements (vitamins, salts, etc.) Copyright © 2010 Society of Chemical Industry     

VOC — or not? Determination of an important environmental parameter

Conclusions  The DSC method has been shown to be a fast method for measurements of boiling points of organic solvents at normal atmospheric pressure. The boiling point temperatures obtained by the DSC method are in very good agreement with existing data, especially concerning solvents of low volatility. These boiling points, together with the definition of a VOC given by the EU directive, enables a rapid characterisation of a solvent as a VOC or not. In a few cases, where the boiling point is between 170–260°C, the vapour pressure must be determined experimentally. The DSC method can be used to measure the boiling points of mixtures and commercial products. If more than one boiling point is measured for a mixture or commercial product the lowest boiling point can be used to define whether the product is a VOC or not. Measurements can also be performed on commercial products containing solids if the solvent content is not too low. Whether or not a product can be described as a VOC is of great significance, especially for the coatings industry. This method can be used in connection with other environmental definitions of VOC, where boiling point is used instead of vapour pressure, for example in connection with labelling. The presentation by Charlotte Nielsen of the paper on which this article is based received the CSI Medallion at the SLF Congress in Lillehammer, Norway, May 1997. The paper is published with the permission of the SLF.     

Atomic-scale mechanism of grain boundary motion in graphene

Grain boundaries (GBs) in graphene can migrate when irradiated by electron beams from a transmission electron microscope (TEM). Here, we present an ab initio study on the atomic scale-mechanism for motion of GB with misorientation angle of ∼30° in graphene. From total energy calculations and energy barrier calculations, we find that a Stone–Wales (SW)-type transformation can occur more easily near GBs than in pristine graphene due to a reduced energy barrier of 7.23 eV; thus, this transformation is responsible for the motion of GBs. More interestingly, we find that a mismatch in the crystalline orientation at GBs can drive the evaporation of a carbon dimer by greatly reducing the corresponding overall energy barrier to 11.38 eV. After evaporation of the carbon dimer, the GBs can be stabilized through a series of SW-type transformations that result in GB motion. The GB motion induced by evaporation of the dimer is in excellent agreement with recent TEM experiments. Our findings elucidate the mechanism for the dynamics of GBs during TEM experiments and enhance the controllability of GBs in graphene.     

Change in Refractive Index of a Borosilicate Glass Fiber Annealed Below the Glass Transformation Temperature

Glass fibers pulled from multihole bushings can have a slight difference in thermal history that causes a distribution in the refractive index that can be narrowed by annealing the fibers. The kinetics for the initial stage change in refractive index for fiber annealed between 300° and 500°C are best described by a second-order reaction with an activation energy of 120° 17 kj/mol. The improved uniformity in refractive index for annealed fibers is indicated by a decrease in the half-height width of the optical transmission versus temperature curve for glass fiber immersed in a liquid. The standard deviation in the refractive index of glass fibers with a bimodal distribution in diameter decreases from 8 × 10^-4≤0.0002 to 4 × 10^-4 0.0002 after the fibers are annealed at 400°C for 1 h.     

Temperature gradient chemical vapor deposition of vertically aligned carbon nanotubes

We present temperature gradient chemical vapor deposition (TG CVD) for producing vertically aligned (VA-) carbon nanotubes (CNTs). Independent heaters on the gas inlet and catalyst substrate sides of a cold-wall, vertical CVD reactor can modulate the gas temperature gradient to lead to controlled thermal histories of acetylene precursor. Our growth results reveal that such a precursor thermal history can play a significant role in the growth and structural features of the resultant VA-CNTs. We find several gas thermal zones particularly important to the VA-CNT growth by evaluating the precursor dwell time in different zones. Thermal treatment of the acetylene precursor at 600–700 °C is found crucial for the synthesis of VA-CNTs. When this thermal zone is conjoined in particular with a zone >700 °C, efficient growths of single-walled and double-walled VA-CNTs can be achieved. These gas thermal zones can contribute to VA-CNT growths by mixing various secondary hydrocarbons with acetylene, corroborated by the results of our reacting flow simulation. Our findings emphasize the influence of gas-phase reactions on the VA-CNT growth and suggest that our TG CVD approach can be practically utilized to modulate complex gas-phase phenomena for the controlled growth of VA-CNTs.     

Isoelectric Focusing of Proteins in Gel Media

Abstract

Separation of proteins according to their isoelectric point can be performed in a pH gradient formed by stationary electrolysis of carrier ampholytes. The pH gradient is stabilized by the use of polyacrylamide, agarose, and Sephadex gels. Separated proteins can be detected by fixation with trichloroacetic acid followed by nonspecific staining, by specific staining, or through immunodiffusion techniques. Isoelectric focusing of proteins in gel media can be carried out in gel columns or on thin-layer plates by using conventional electrophoresis apparatus. Electrofocusing can be followed by electrophoresis in gel media for more complete separation of components.

Multiple samples of microgram quantities can be analyzed simultaneously by simple and rapid procedures. These methods have both analytical and preparative applications in protein fractionation work.     

A phosphorus budget of a poultry farm and a dairy farm in the southeastern U.S., and the potential impacts of diet alterations

Current and potential environmental problems associated with P transport from lands receiving high application rates of animal waste are a major concern. Phosphorus management strategies are needed to reduce P loading on land. This study was conducted to compare on-farm P budgets for a modern broiler farm and a dairy farm under traditional diets and management practices. Phosphorus inputs, recycling and outputs were assessed for both farms. A typical broiler and a dairy farmer from North Carolina were interviewed and pertinent information for the study was obtained, in cooperation with extension agents, and other professionals associated with the farms. The annual on-farm P surplus for the broiler farm was 6,380 kg, while that for the dairy farm was 1,141 kg. This corresponds to an annual application of 65 kg P ha^–1 for the broiler farm and 20 kg P ha^–1 for the dairy farm in excess of removal. The potential for reducing P surpluses by the addition of phytase enzymes and/or the use of low phytic acid corn (Zea mays L.) feed in the broiler farm diet was also assessed. Estimates by animal nutritionists indicate that feed supplementation with phytase enzyme can reduce the broiler farm's P surplus by 33%. The use of low phytic acid corn can reduce the surplus by 49% and a combination of the two can reduce the surplus by 58%. In this study, the incorporation of soybean (Glycine max (L.) Merr.) and alfalfa (Medicago sativa) land into the waste utilization plan of the dairy farm decreases the annual P surplus from 20 to 9 kg P ha^–1. The use of new feed technology and expanding waste application to a larger land base can significantly alter the P budgets of broiler and dairy farms and reduce P surpluses, minimizing the risk of environmental problems.     

皮胶原纤维负载钦对核工业废水中铀的去除(英文)

Effective recovery of UO2+2 from wastewater is essential for nuclear fuel industry and related industries.In this study,a novel adsorbent was prepared by loading titanium(Ti4+) onto collagen fiber(TICF),and its physical and chemical properties as well as adsorption to UO2+2 in nuclear fuel industrial wastewater were investigated.It is found that TICF can effectively recover UO2+2 from the wastewater with excellent adsorption capacity.The adsorption capacity is 0.62 mmol·g-1 at 303 K and pH 5.0 when the initial concentration of UO2+2 is 1.50 mmol·L-1.The adsorption isotherms can be described by the Langmuir equation and the adsorption capacity increases with temperature.The effect of co-existed F on the adsorption capacity for UO2+2 is significant,which can be eliminated by adding aluminum ions as complexing agent,while the other co-existed ions in the solutions,including HCO-3,Cl-,NO-3,Ca2+,Mg2+ and Cu2+,have little effect on the adsorption capacity for UO2+2.The saturated TICF after UO2+2 adsorption can be regenerated by using 0.2 mol·L-1 nitrate(HNO-3) as desorption agent,and the TICF can be reused at least three times.Thus the TICF is a new and effective adsorbent for the recovery of UO2+2 from the wastewater.     

Novel Electrokinetic Microfluidic Detector for Evaluating Effectiveness of Microalgae Disinfection in Ship Ballast Water

Ship ballast water treatment methods face many technical challenges. The effectiveness of every treatment method usually is evaluated by using large scale equipment and a large volume of samples, which involves time-consuming, laborious, and complex operations. This paper reports the development of a novel, simple and fast platform of methodology in evaluating the efficiency and the best parameters for ballast water treatment systems, particularly in chemical disinfection. In this study, a microfluidic chip with six sample wells and a waste well was designed, where sample transportation was controlled by electrokinetic flow. The performance of this microfluidic platform was evaluated by detecting the disinfection of Dunaliella salina (D. salina) algae in ballast water treated by sodium hypochlorite (NaClO) solution. Light-induced chlorophyll fluorescence (LICF) intensity was used to determine the viability of microalgae cells in the system, which can be operated automatically with the dimension of the detector as small as 50 mm × 24 mm × 5 mm. The 40 µL volume of sample solution was used for each treatment condition test and the validity of detection can be accomplished within about five min. The results show that the viability of microalgae cells under different treatment conditions can be determined accurately and further optimal treatment conditions including concentrations of NaClO and treatment time can also be obtained. These results can provide accurate evaluation and optimal parameters for ballast water treatment methods.     

Calibration of size-exclusion chromatography columns with polydisperse polymer standards. II. Applications

New methods for calibrating SEC columns by means of polydisperse polymer samples with known M_n and M_w have been tested with computer-generated chromatograms and with experimental data of high-performance SEC. Calculations with the artificial chromatograms show that accurate calibration dependences can be recovered even when polymers with broad and/or bimodal molecular weight distributions are used as standards. Polystyrene calibration calculated by the proposed method from chromatograms of five polydisperse polystyrenes follows closely the curve obtained in a conventional manner from nine narrow polystyrene standards. The dependence log M vs. ν for PMMA determined from chromatograms of six PMMA samples with moderately broad molecular weight distributions agrees well with the curve obtained by shifting the dependence for polystyrene using the universal calibration concept. The new method is particularly useful when SEC columns are to be calibrated for dextrans in water, where only a few standards having a rather broad molecular weight distribution are available, and can considerably improve the accuracy of molecular weight determination by SEC.     

Cyclic Peptides Made by Linking Synthetic and Genetically Encoded Fragments

Cyclic peptides can be highly valuable as bioactive molecules, both for biomedical applications and in basic research. We introduce a new fragment‐based approach to access cyclic peptide structures in which one fragment is of synthetic origin and the other is genetically encoded. The synthetic peptide, which can contain one or more non‐proteinogenic building blocks, is coupled to the recombinantly expressed peptide through two bonds, one formed by protein trans‐splicing with a split intein and the other by oxime ligation. Semisynthetic macrocycles were obtained with high efficiency for various sequences and ring sizes; they can be prepared in quantities sufficient for initial bioactivity tests. We also prepared lipidated and d ‐amino‐acid‐containing peptides that were inspired by the peptide antibiotic daptomycin. Such structures are not accessible by other methods that harness the power of simple genetic diversification in the DNA‐encoded part of the peptide.     

Silicon contamination of polypropylene films from glass reactors in a BCl3 RF cold plasma

Summary Cold plasma chemistry can be used for surface modification and/or grafting of polymeric substrates for enhanced properties. In addition to interaction with the substrate, plasma reactions can also occur at other surfaces confined to the reactor. Contamination of polypropylene (PP) substrates with silicon, originating from the reactor walls in a BCl₃ plasma, has been shown to occur based on ESCA measurements and the presence of Si-based compounds in the gaseous phase has been shown by GC-MS and high resolution MS for the plasma generated molecular mixture. The Si incorporation is similar to that found with CF₄ plasmas where a shorter treatment time resulted in higher Si incorporation. These results indicate that reactor wall-origin contaminations can accompany plasma treatments, interfere with the the main reaction mechanisms and create serious problems for achieving the desired surface properties.     

The hydrochloric acid route for phosphate rock

When phosphate rock is leached with hydrochloric acid, radium can be removed by co-precipitation with Ba_0.4Ca_0.6SO₄ and uranium by extraction with a 5% solution of tributyl phosphate in hexane or Varsol. Phosphoric acid is then separated from calcium chloride solution and other impurities by extraction with undiluted tributyl phosphate. The lanthanides can be precipitated from the raffinate by NH₃, and CaSO₄.2H₂O by H₂SO₄ to regenerate HCl for recycle. The organic phase containing H₃PO₄ can be stripped by NH₃ to yield ammonium phosphate and to regenerate the tributyl phosphate for recycle. Fluorine can be precipitated from the initial leach solution as Na₂SiF₆.     

Bioengineered Silkworm for Producing Cocoons with High Fibroin Content for Regenerated Fibroin Biomaterial-Based Applications

Silk fibroin exhibits high biocompatibility and biodegradability, making it a versatile biomaterial for medical applications. However, contaminated silkworm-derived substances in remnant sericin from the filature and degumming process can result in undesired immune reactions and silk allergy, limiting the widespread use of fibroin. Here, we established transgenic silkworms with modified middle silk glands, in which sericin expression was repressed by the ectopic expression of cabbage butterfly-derived cytotoxin pierisin-1A, to produce cocoons composed solely of fibroin. Intact, nondegraded fibroin can be prepared from the transgenic cocoons without the need for sericin removal by the filature and degumming steps that cause fibroin degradation. A wide-angle X-ray diffraction analysis revealed low crystallinity in the transgenic cocoons. However, nondegraded fibroin obtained from transgenic cocoons enabled the formation of fibroin sponges with varying densities by using 1–5% (v/v) alcohol. The effective chondrogenic differentiation of ATDC5 cells was induced following their cultivation on substrates coated with intact fibroin. Our results showed that intact, allergen-free fibroin can be obtained from transgenic cocoons without the need for sericin removal, providing a method to produce fibroin-based materials with high biocompatibility for biomedical uses.     

幅宽14m PO涂布膜机组的关键技术

介绍了聚烯烃(PO)涂布膜的性能以及在线涂覆法生产PO膜的工艺流程及工艺难点,研究了PO膜对螺杆、机头、自动膜厚控制系统、牵引张力控制以及收卷的特殊要求。结果表明:采用Φ150低剪切分离型螺杆可以很好地加工长支链茂金属树脂;采用新型中心进料机头和自动横向厚度控制系统可以提高PO膜的厚度均匀性,满足涂覆的要求;采用S型牵引装置可以解决宽幅牵引夹紧时两头紧、中间松的"哈壳"现象;采用摆动折叠方法可以解决宽幅膜较难卷绕的有关问题。试验表明,幅宽10 m以上的PO膜并非不可生产,配置合理、技术先进的PO涂布膜机组可以生产幅宽14 m的PO膜。     

Oligomerization of isobutene over aluminum chloride-loaded USY zeolite catalysts

Oligomerization of isobutene has been investigated over AlCl₃-loaded USY zeolite catalysts in order to produce triisobutenes or remove/separate isobutene from C₄ streams. Stable isobutene conversion and high selectivity for trimers and tetramers were attained over the modified zeolite with high ratio of Lewis acid site-to-Brønsted acid site, suggesting that a potential trimerization catalyst can be obtained easily by loading a Lewis acid into an acidic zeolite catalyst. This catalyst can be facially produced by physical mixing and can be easily restored its activity after deactivation by simple calcinations.     

Nanostructured plasma coatings to obtain multifunctional textile surfaces

Nanostructured surfaces are of great interest, since they provide a high surface area. A high functionality can thus be obtained by ultrathin coatings. Plasma polymerization of acetylene mixed with ammonia (C₂H₂/NH₃) was used in a regime where both deposition and etching processes took place yielding a nanoporous, crosslinked network with accessible functional groups. These plasma coatings can be used as permanent hydrophilic treatment or for substrate-independent dyeing when deposited on textile fabrics. Increasing color intensity with film thickness proved that accessible amine groups were deposited within a nanoporous hydrocarbon matrix. Using plasma co-sputtering of a silver target, Ag nano particles can be in situ embedded within the growing plasma polymer yielding a well-defined size and distribution of nano particles at the coating surface. Hence, an anti-microbial activity was achieved. Multifunctional textile surfaces can thus be obtained by adjusting combined properties such as wettability, functional group density as well as anti-bacterial and bio-responsive surfaces. Scale-up of these combined plasma processes is enabled by control of plasma chemistry regarding energy input into the plasma zone and plasma physics by surface interaction with energetic particles.     

Low-field NMR studies of polymer crystallization kinetics: Changes in the melt dynamics

The free induction decay in ¹H NMR experiments carried out for crystallizing polymers can be directly decomposed in contributions from crystals, melt-like regions and amorphous regions with a reduced mobility. Here, the results of time-dependent experiments conducted with the aid of a cost-efficient low-field NMR instrument are presented, obtained for sPP, P?CL and P(EcO). Crystallization isotherms are compared with those obtained by X-ray scattering and dilatometry. There are some minor systematic deviations which can be explained and accounted for. For all systems, a large fraction of amorphous chain parts in regions with a reduced mobility is found.