Advanced Materials Research Vols. 455-456

Abstract: Corn starch was partially hydrolyzed by treating the starch dispersions with heat stable a-amylase. Dextrose equivalent (DE) value of 2.5–6.5 was achieved by hydrolyzing the starch samples (30 % w/w) at 95 °C. The hydrolyzed starch granules with different DE values were analyzed by textural analyzer and rheometer. The results showed that the corn starch-based fat mimics with the concentration of 30 % and DE value of 3.5 could form relatively firmer gel. The corn starch-based fat mimics with DE value of 3.5 were analyzed by X-ray diffraction, scanning electron microscopy and dynamic mechanical analyzer (DMA). The X-ray diffraction analysis showed that the hydrolysis of corn starch-based fat mimics mainly occurred in the amorphous region. The scanning electron micrographs showed that the size of the fat mimics was about 5µm. and the DMA analysis showed that the glass transition temperature (Tg) of the fat mimics decreased 5 °C than the original corn starch, which suggested that the corn starch-based fat mimics had the similar storage stability as the original corn starch.

Abstract: Nutrient-rich milk is the natural medium, easy to spoilage. Some physical parameters will change with milk deterioration such as density, viscosity, surface tension coefficient, light transmittance, etc. Detecting these physical parameters is useful to monitoring the deteriorate degree of milk. This article focuses on the surface tension efficient and viscosity of milk by monitoring its deteriorate process. The experimental results show that deterioration of milk is indeed accompanied with the change of surface tension coefficient and viscosity. In compare with surface tension coefficient, viscosity dramatically change after deterioration.

Abstract: Low-energy ion implantation is a new mutation source, which has the characteristic of light damage, high mutation rate, and a broad spectrum mutation. In order to obtain industrial strain with high L-(+)-lactic acid yield, the original strain Lactobacillus casei CICC6028 was mutated by nitrogen ion beam implantation. It was found that the original strain had a higher positive mutation rate when the output power was 10keV and the dose of N+ implantation was 50×2.6×1013 ions/cm2. The mutant N-2 was obtained for many times screening and its yield of L-(+)-lactic acid was 136 g/L which was improved by 38.8% compared with the original strain whose yield of L-(+)-lactic acid was 98g/L as the cultivation time was 120h. The initial screening methods were also studied in this work but it was found that the transparent halos method was unavailable, so the initial screening was performed by shake flask fermentation. HPLC chromatogram was used to analyse the purity of L-(+)-lactic acid that was produced by the mutant strain N-2, and the result indicated the main production of N-2 was L-(+)-lactic acid and there was no other acid almost.

Abstract: Construct ionic liquid - salt aqueous two-phase system for extracting yeast DNA. By using NaOH solution to process yeast, leaching the nucleic acid by ultrasonic assisting, variety of salts’ aqueous two-phase influence on the ionic liquid 1-butyl-3-methylimidazolium fluoroborate are discussed, and the influence of additive quantity of KH2PO4 and PH on the ionic liquid aqueous two-phase system for extraction of nucleic acid are studied. The result shows that process the yeast with 0.3% NaOH solution, assisted by ultrasound with power of 80W, temperature 60 °C, 3 hours’ extraction. KH₂PO₄ take obvious advantage in the formation of ionic liquid aqueous two-phase system. In the process of extraction nucleic acid from [BMIM] BF4-H2O-KH₂PO₄ aqueous two-phase process of nucleic acid, the best B-R buffer PH is 8.95, when the additive dosage of KH₂PO₄ is 2.000g, A260/A280 in the supernatant is smaller than control group, the substratum which rich in ionic liquid contains more nucleic acid than the supernatant, and A260 in the supernatant is more than that in the control group. Therefore, we conclude that the ionic liquid aqueous two-phase has a relatively good effect in extraction of nucleic.

Abstract: The non-covalent interaction between a series of N-phosphoryl dipeptides (or methyl esters) (DPP) and cytochrome C was studied by ESI-MS. The function of different groups in DPP and binding sites of protein were investigated. The results revealed that hydroxyl and aromatic ring in DPP were both important group for the interaction, and aromatic ring had double functions on the interaction. In addition, the molecular size, flexibility and steric hindrance showed obvious effects on the interaction, while, the chirality, sequence and length of carbon chains (changing 1−2C) of amino acid residue in DPP showed little effects on the interaction under the experimental conditions. The results provide some useful information and theoretical basis for the molecular design of peptide drugs.

Abstract: . Rice and wheat are the traditional food for Chinese people, as well as the main crop candidates for space bioregenerative life support systems. Recycling of inedible parts of rice and wheat is an important issue concerning the system. In order to determine whether the mixed-substrate of rice and wheat’s inedible parts is suitable for plant cultivation, soil-like substrate made from rice and wheat was tested in an aqueous extract germination experiment. The effects of different concentrations of aqueous extract on seed vigor, seedling growth and development situations and the physiological and biochemical characteristics of wheat, lettuce and pumpkin were studied, and the presence and degrees of allelopathic effects were analyzed. The test results show that this type of soil-like substrate can exert different degrees of allelopathic effect on wheat and lettuce; this allelopathic effect is related to the concentration of soil-like substrate aqueous extract. With the increase of extract concentration, the seed germination, root length and shoot fresh weight of wheat decreased; and every concentration of aqueous extract showed significant inhibition on the root length and root fresh weight of lettuce. However, this type of soil-like substrate showed few effect on the growth of pumpkin seedlings. Content changes of chlorophyll and endogenous hormones in wheat and lettuce seedlings, and the chemical compositions of soil-like substrate were measured. Besides, the mechanism of allelopathic effect was analyzed.

Abstract: Natural petroleum sulfonates (PS) was separated, purified and divided into several fractions by a new method liquid-liquid & soxhlet extraction. The effects of heating time, volume ratio of extractants (isopropanol aqueous solution-50/50 (by volume) : n-pentane), gradient solvent types, extracting time & times on the separation efficiency are discussed, respectively. And the extracted mineral oil was anlalyzed by IR spectra, the average equivalent weight of each extracted PS fraction was measured by ESI-MS. The experimental results show that the volatiles in natural plant-manufactured PS can evaporate thoroughly in 3.5h at 130°C, and when the volume ratio of stated extractants is 3:1, after several times extraction & anti-extraction, the extracted mineral oil is PS-free, and the purified PS is successfully separated from inorganic salt, meanwhile the purified PS was divided into four fractions, whose average equivalent weight are (toluene extract) 595.03, (dichloromethane extract) 486.00, (isopropanol extract) 474.85 and (alcohol extract) 384.5g/mol, respectively. The proposed method is superior to the traditional liquid-liquid extraction for simplified steps and bifunction with PS purifying & fraction dividing, can separate efficiently industrial PS and other similar mixtures.

Abstract: When precipitated silica was prepared from yellow phosphorus slag by the phosphoric acid leaching, the Fe content can not meet the quality requirements of the product. This article indicates the method of purifying precipitated silica with nitric acid solution, which may decrease the Fe content to about 0.02%. The purification optimum technical conditions are: the nitric acid concentration 8%, reaction time 2.0 hours, reaction temperature 343.15K, fluid solid ratio 4:1, stirring speed 300 rpm.

Abstract: The electrochemical degradation pathway of phenol, as model organic pollutant, was investigated on antimony doped tin dioxide electrode based on titanium anode (Ti/SnO₂). Many intermediates of electrochemical degradation of phenol on Ti/SnO₂ were identified and quantified by HPLC. These intermediates were assured as aromatic ring-compounds (hydroquinone, catechol, benzoquinone, et al) and short chain fatty acids (maleic acid, fumaric acid, formic acid, cis muconic acid and 2-oxoglutaric acid, et al). Electrochemical degradation tests were conducted with some intermediates as substrates, including the electrochemical oxidation of formic acid, acetic acid, oxalic acid, malonic acid, acrylic acid, succinic acid, fumaric acid, maleic acid, and 2-oxaglutaric acid, et al. The degradation pathway of phenol on Ti/SnO₂ anode was concluded. It is proven that the pathway relates to the element composition on the electrode surface. These findings demonstrate electrochemical degradation of organic pollutants mechanism and help to practical use of catalytic anodes materials.

Abstract: Nanocomposites were obtained by mixing elastomeric copolymer and nanoSiO₂ in double-screw extruder at 130-150°C, in which the elastomeric copolymer was prepared by copolymerization of poly (methyl methacrylate (PMMA) macromonomer and butyl acrylate (BA) in benzene using azobisisobutyro-nitrile (AIBN) as initiator. The results indicated that increasing the amount of PMMA, the molecular weight of PMMA and copolymers, nanosilica charged resulted in improving the tensile strength and modulus at 300% elongation of nanocomposites, on the contrary, decreasing ultimate elongation and permanent set decrease. In additions, the tensile strength and the modulus at 300% elongation of nanocomposites reached to a maximum while the mass ratio of nanoSiO₂ to copolymer was 3%.