Papers by Keyword: Amino Acid

Abstract: Novel approaches to engineer nanoparticles with desired chemical characteristics open new opportunities to utilize such materials for assorted applications. In this context, various methods have been developed to prepare metal nanoparticles. In the present work, we report a single-step synthesis method to prepare silver nanoparticles by using Carbidopa which is useful in treating Parkinson's disease to increase the dopamine level of the brain. Here we used the Carbidopa drug as a capping agent. Nanoparticles were characterized by Uv-Visible spectroscopy, Particle size Analyzer (PSA), dynamic light scattering (DLS), Powder X-ray Diffractometry (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Transmission electron microscopy (TEM). Then amino acid detection study was performed with all 24 amino acids, which provides the successful data for sensing the amino acid L-dopa. These prepared nanoparticles were further applied for metal analyte studies which reveal that lead can be sensed successfully by using these nanoparticles. Nanoparticle also shows radical scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH).

Abstract: Amino acids are known as novel kinetic hydrate inhibitor (KHI) for hydrate mitigation, however, the performance in oil system is not well justified up to date. In this study, the kinetics of methane hydrates in oil dominated systems using valine amino acid has been studied in a high-pressure gas hydrate reactor at 80 bar and 1 °C using the constant cooling method. Drilling oil was used in this work to mimic the oil phase in flow assurance. The results shows that valine delays hydrate formation nucleation time 4 times compared with pure water systems. This finding is contrary to most claims in literature that shows that valine promotes hydrate in gas dominated system. However, the inhibition impact of valine exhibited in this work might be due to the presence of oil with is absence in the most literature studies. The findings in the work are useful for hydrate mitigation using amino acids in flow assurance.

Abstract: Using L-octanoyl alanine and L-octanoyl phenylalanine as precursors, they are reacted with magnesium hydroxide to prepare two low-molecular complexes Mg(oct-L-ala)₂ and Mg(oct-L-phe)₂. The composition and structure of the two complexes are characterized by elemental analysis, nuclear magnetic resonance spectroscopy and moisture analyzer, with the solubility and aggregation behavior of the complexes studied. A comparison of the two complexes shows that the Mg(oct-L-ala)₂ complex exhibits better solubility and is easier to aggregate in the mixed solution. In addition, the aggregated solid formed by the aggregation of these two complexes in the solution has optically heterogeneous properties. After further heating and cooling treatment, the Mg(oct-L-phe)₂ complex still retains the optically anisotropic state (liquid crystal state), while the Mg(oct-L-ala)₂ complex forms an optically homogeneous morphology (glass state). This may be affected by the benzene ring functional group in the Mg(oct-L-phe)₂ complex.

Abstract: The magnetic ferroferric oxide nanoparticles were modified with L-lysine to prepare immobilized carriers(Fe₃O₄-Lys), which was applied to the immobilization of Saccharomyces cerevisiae CGMCC No. 2230. The optimal immobilization conditions for preparation of Fe₃O₄-Lys-Cells were Fe₃O₄-Lys 0.01 g, cell dry weight 3 g, pH 7, 3 h, 30 °C. Ethyl R-4-chloro-3-hydroxybutyrate was gained by asymmetric reduction of ethyl-4-chlorooxobutanoate with Fe₃O₄-Lys-Cells as catalysis. 0.672 mol/L COBE can be converted completely in 40 h in the shaker, while only 24 h in the alternating magnetic field. The conversion and enantiomeric excess(e.e.) of (R)-CHBE reached 100% and more than 99.9%, respectively.

Abstract: The research group Combined with purple cloud point extraction method and UV spectroscopy technology .The best extraction conditions of Cu-Glycine is: 230nm, pH value of 9.0, NaCl solution 4.0mL, Triton X-100 solution 50.0 mg/ml,1.0mL. This method is applied to environmental water samples in the separation of trace amounts of copper and measured.

Abstract: Golden Guanyin tea from Lishui city, Zhejiang province, is a new variety of Oolong tea with special aromas. To analysis the aroma compounds, two sample preparation methods of tea grinding and water distillation were carried out, then the tea aromas and amino acids were detected. The main aroma compounds were of dimethyl sulfide, butanal, ethyl acetate, butanedial and cyclobutene by the grinding method, as for the distillation method, the aroma compounds detected were of benzeneacetaldehyde, phenylethyl alcohol, benzyl nitrile, Geraniol, indole, cyclopentene, phenylethyl butyrate, nerolidol, methyl jasmonate, 2,2'-dipyridylamine, benzenedicarboxylic acid, cyclopentaneacetic acid, methyl jasmonate ester, dibutyl phthalate and phytol. Golden Guanyin tea samples had 16 kind amino acids, in which glutamic acid and leucine were of 0.047 and 0.041 mg/mL, respectively, and the minimum ones were of cysteine and methionine in concentration of 0.004 mg/mL. The results will be helpful in the quality improvement and production of the new Golden Guanyin tea.

Abstract: Hydrolysis of corn residue, one of major by-products after the extraction of starch, in sub-critical water to produce amino acids was conducted in this paper. The quality and quantity analysis of amino acids in hydrolysate were carried out by Amino Acid Analyzer (Biological Liquid Chromatography), and the main amino acid of arginine were obtained. The effects of Solid-water ratio, reaction temperature and time on the yield of the arginine were investigated. It was found that the optimum hydrolysis conditions for arginine preparation from the corn residue in sub-critical water are as follows: solid-water ratio 0.05, reaction temperature 473K and reaction time 1h, and the yield of arginine 10.23%. The results show that the sub-critical water hydrolysis process has the advantages of high efficiency, simple process and friendly to environment.

Abstract: This research was to study the efficiency of amino acids such as alanine, asparagine and cysteine, which were applied as antioxidant both in green and vulcanized natural rubbers (NR) for STR5L and RSS3, comparing with the use of synthetic antioxidant, i.e., N-(1, 3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6-PPD). In the case of green NR, the rubber was mixed with antioxidants on a two-roll mill machine. Then, the specimens were shaped by hydraulic hot press. In the case of cured NR, conventional system of the sulfur vulcanization was carried out at 150°C for t₉₅. Both green and vulcanized NRs specimens were subjected to heat aging test at 100°C for 24, 48, 72 and 96 hours. Another mixed green and cured NR were also tested the plasticity by Wallace plastometer and ozone resistance following ISO 1431/1, respectively. From the experiment, it was found that although plasticity retention index (PRI) of the green NR mixed with each type of amino acids were lower than those mixed with 6-PPD, alanine exhibits the best antioxidative property among all of amino acids. Considering at the reduction in tensile properties, stress at 200% strain of both raw STR5L and RSS3 mixed with 1 phr of 6-PPD after heat aging test were totally lower than those applied with alanine, asparagine, and cysteine. In addition, for the cured NR specimens, the tensile results are agreeable with the PRIs value of the raw NR. However, NR vulcanizates preserved with each amino acid inhibited the crack length under ozone test better than that mixed with 6-PPD. Anti-oxidative mechanism of amino acids as well as 6-PPD is available as chain breaking donors (CB-D) mechanism. This might be concluded that alanine can be applied as a natural antioxidant in the green and vulcanized NR better than other amino acids, but not for 6-PPD. Moreover, three types of amino acid can be used as a good antiozonant for the sulphur vulcanized NR.

Abstract: Branched copolymer of lactic acid/bicine (N, N-bis (hydroxyethyl) glycin) was prepared directly by melt polycondensation from lactic acid and bicine. The branched structure of copolymer of lactic acid/bicine was characterized by ¹H NMR and intrinsic viscosity. Although the molecular weigh of copolymer was lower than that of homopolymer of lactic acid, the hydroxyl number of the copolymer was higher than that of homopolymer. All the data indicated the molecule structure of copolymer was branched. Compared with homopolymer of lactic acid, the crystallinity of the branched copolymer decreased and the thermal stability increased.

Abstract: Three new rare earth ternary complexes (NdLL'•4H2O, EuLL'•4H2O and LaLL'•4H2O) have been prepared with rare earth nitrates, tryptophan (L) and sodium citrate (NaL'). The characteristics of the complexes were identified by elemental analysis, IR, molar conductivity solubility and TG-DTA. The results showed the complexes have constant composition of RELL'•4H2O. And all of the rare earth ternary complexes have anticoagulant action.