Behavior of hydrothermal decomposition of silk fibroin to amino acids in near-critical water

The behavior of protein decomposition to amino acids in near-critical water is elucidated by using silk fibroin as a model compound. Results show that serine (Ser), aspartic acid (Asp) and other complex amino acids, obtained initially in significant amount, gradually decreased as reaction time and temperature were increased. At temperature higher than 523 K, it is likely that Gly and Ala underwent further decomposition. Regarding the effect of various additives, no significant effect on the yield of amino acids was observed with the addition of oleic acid. However, the presence of NaOH and formic acid (FA), both in 5 mol% aqueous solution, had significant effect on the yield. The effect of alkalinity and acidity, the production of amino acids was enhanced in either acidic or basic conditions.     

Effects of various reaction conditions on the hydrothermal treatment of polypeptone

This study investigated the production behavior of amino acids from polypeptone under various operation parameters and reactor modes (batch and continuous). In the batch experiments, the effect of heating time on amino acid production was studied using different type of reactor materials (Hastelloy (HAS) and SUS). The results showed that the production behavior of amino acids such as Gly, Ala, and Leu was quite similar regardless of reactor materials. To further investigate the relationship of reaction time on the amino acids production, experiments were conducted in batch and continuous reaction at the same conditions (T=523 K and P=30 MPa). The results showed that it is possible to get the same result at the same reaction time using a batch and continuous reaction mode if the reaction time is started after heating time in a batch reaction mode. From the study of reaction pressure, it was observed that the production of amino acids is not favored at reaction pressure between 4 and 30 MPa at 523 K.     

Controlled fabrication of nanosized TiO2 hollow sphere particles via acid catalytic hydrolysis/hydrothermal treatment

TiO₂ hollow spheres of controlled size were synthesized by combined acid catalytic hydrolysis and hydrothermal treatment, which involves the deposition of an inorganic coating of TiO₂ on the surface of carbon spheres prepared by a hydrothermal method and subsequent removal of the carbon spheres by calcination in air. The obtained TiO₂ hollow spheres were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and powder X-ray diffraction. The results revealed that the size and surface morphology of the TiO₂ hollow spheres can be controlled by adjusting the concentration of the aqueous solution of glucose used to produce the template carbon spheres. Increasing the concentration of the glucose solution increased the average diameter of the TiO₂ hollow spheres from 190 to 300 nm. TiO₂ hollow spheres prepared using a glucose solution with a concentration of 0.7 mol/L are uniform in size with a diameter of 220 nm and shell thickness of 28 nm. The phenol removal rate of the sample prepared by calcination at 600 °C is 1.35 times higher than that of TiO₂ made by the same method without using the carbon template.     

Oxidation of Amino Acids,Peptides and Proteins by Ozone: A Review

The kinetics and products of the reaction of ozone with specific amino acids, peptides, and proteins are reviewed based on studies reported in the literature. Ozone reacts mainly with the unprotonated amino group of the acids and the second-order ozone rate constants for these reactions, except for cysteine, methionine, and tryptophan, vary by about two-orders from 2.6?×?10⁴ to 4.4?×?10⁶ M^?1s^?1. The site of attack on cysteine and methionine by O₃ is at the sulfhydryl rather than the amino group to give sequential O-atom addition products. The order of reactivity for the oxidation of amino acids by O₃ at pH 8 is cysteine > tryptophan ≈ methionine > phenylalanine ≈ histidine > others, with half-lives mostly in the range of milliseconds to tens of seconds (1 mg L^-1 O₃ dose). Reactions of O₃ with aliphatic amino acids form nitrate, ammonia, and one or two carbon atom-containing carbonyl and carboxylic byproducts. In the ozonolysis of peptides and proteins, oxidation by O₃ occurs at the tyrosine, tryptophan, histidine, cysteine, and methionine residues. Oxidation of proteins results in changes in their folding ability and tertiary structures.     

Bio-oil production from oil palm biomass via subcritical and supercritical hydrothermal liquefaction

This paper presents the studies on the liquefaction of three types of oil palm biomass; empty fruit bunch (EFB), palm mesocarp fiber (PMF) and palm kernel shell (PKS) using water at subcritical and supercritical conditions. The effect of temperature (330, 360, 390 °C) and pressure (25, 30, 35 MPa) on bio-oil yields were investigated in the liquefaction process using a Inconel batch reactor. The optimum liquefaction condition of the three types of biomass was found to be at supercritical condition of water i.e. at 390 °C and 25 MPa, with PKS yielding the maximum bio-oil yield of 38.53 wt%, followed by EFB and PMF, with optimum yields of 37.39 wt% and 34.32 wt%, respectively. The chemical compositions of the bio-oils produced at optimum condition were analyzed using GC–MS and phenolic compounds constituted the major portion of the bio-oils, with other minor compounds present such as alcohols, ketones, aromatic hydrocarbons and esters.     

Synthesis and performances of bio-sourced nanostructured carbon membranes elaborated by hydrothermal conversion of beer industry wastes

Hydrothermal carbonization (HTC) process of beer wastes (Almaza Brewery) yields a biochar and homogeneous carbon-based nanoparticles (NPs). The NPs have been used to prepare carbon membrane on commercial alumina support. Water filtration experiments evidenced the quasi-dense behavior of the membrane with no measurable water flux below an applied nitrogen pressure of 6 bar. Gas permeation tests were conducted and gave remarkable results, namely (1) the existence of a limit temperature of utilization of the membrane, which was below 100°C in our experimental conditions, (2) an evolution of the microstructure of the carbon membrane with the operating temperature that yielded to improved performances in gas separation, (3) the temperature-dependent gas permeance should follow a Knudsen diffusion mechanism, and (4) He permeance was increasing with the applied pressure, whereas N₂ and CO₂ permeances remained stable in the same conditions. These results yielded an enhancement of both the He/N₂ and He/CO₂ permselectivities with the applied pressure. These promising results made biomass-sourced HTC-processed carbon membranes encouraging candidates as ultralow-cost and sustainable membranes for gas separation applications.     

Adsorption and desorption dynamics of amino acids in a nonionic polymeric sorbent XAD-16 column

A separation technique for amino acids, phenylalanine and tryptophan, from aqueous solution was studied in a column that was packed with a polymeric resin, XAD-16. This technique is based on a cyclic operation that has three typical steps such as adsorption, desorption, and washing. In particular, the desorption step for amino acids from the resin was carried out by using organic solvents, isopropyl alcohol and methanol. The desorption mechanism was assumed to be a competitive adsorption between amino acids and solvents, and the ideal adsorbed solution theory (IAST) based on the Langmuir equation as a single component isotherm was used in describing multicomponent equilibria. Adsorption and desorption breakthrough curves of the two amino acids were measured under various experimental conditions such as concentration, flow rate, and column length, in order to check the feasibility of the resin as a medium for the separation of amino acids. It was found that this separation technique could be a promising one for this purpose. Also, a simple dynamic model was formulated to describe both adsorption and desorption breakthrough curves of amino acids.     

Water vapor adsorption and desorption of mesoporous materials derived from metakaolinite by hydrothermal treatment

Mesoporous materials were prepared by hydrothermal treatment of powder-compacts consisting of metakaolinite, quartz and slaked lime with different forming pressures. The hydrothermally solidified materials developed strength despite the formation of hydrogarnet. The hydrothermally solidified materials exhibited a broad pore size distribution of more than 3.4 nm, and the volume and specific surface area increased with decreasing the forming pressure. The hydrothermally solidified materials showed an excellent humidity-controlling ability due to adsorption and desorption of water vapor by utilizing their mesopores.     

赤子爱胜蚓Calreticulin的cDNA和氨基酸序列分析

目的分析赤子爱胜蚓Calreticulin的cDNA和氨基酸序列。方法从本院构建的赤子爱胜蚓cDNA文库中经测序获得其Calreticulin cDNA序列。采用生物信息学分析工具DNAMAN、NCBI ORF finder、ExPASy Protparam、ExPASY Protscale、NCBI Conserved Domains、SignalP 4.1 Server、TMHMM Server v.2.0、SOSUI、NetPhos 3.1 Server、PSORT、SOPMA、ExPASy COILS、SWISS-MODEL分别对Calreticulin的cDNA序列、氨基酸序列、一级结构基本理化性质、亲/疏水性、保守结构域、信号肽、跨膜区、可溶性、磷酸化修饰、亚细胞定位、二级结构、卷曲螺旋域以及三级结构进行预测及分析。结果赤子爱胜蚓Calreticulin cDNA序列长476 bp,其中包含354 bp的开放阅读框,编码118个氨基酸残基;Calreticulin由19种氨基酸组成,呈酸性,为稳定的可溶性亲水蛋白;具有1段Calreticulin超家族保守结构域;不存在信号肽和跨膜结构;具有12个潜在的磷酸化位点;主要存在于细胞核中;二级结构元件主要由α-螺旋(29.66%)和无规则卷曲(50.85%)组成,具有卷曲螺旋;三级结构预测结果与二级结构一致。结论掌握了赤子爱胜蚓Calreticulin的理化性质,预测了其潜在的特征,并分析了其结构,为后续深入开展其功能及分子作用机制的研究提供了理论依据。     

Economic feasibility of a pilot-scale fermentative succinic acid production from bakery wastes

In this paper, the techno-economic study for a pilot-scale production of succinic acid from food waste via fermentation was evaluated. The pilot plant was based in Hong Kong and designed for converting 1 tonne/day of bakery waste into succinic acid. The mass and energy balance of the process was simulated by computer package SuperPro Designer^®. The total capital investment for the plant and the total production cost were US$ 1,118,243 and US$ 230,750/year respectively. Overall revenue generated from the process was US$ 374,041/year. The return on investment, payback period and internal rate of return of the project were 12.8%, 7.2 years and 15.3% respectively. The findings indicated that the fermentative succinic acid production from bakery waste was feasible. This is important for attracting investment and industrialization interest on the biorefinery process using domestic wastes as raw materials.     

Upgrading and dewatering of raw tropical peat by hydrothermal treatment

In this study, hydrothermal upgrading and dewatering of raw tropical peat derived from Pontianak, West Kalimantan-Indonesia was evaluated at temperatures ranging from 150 to 380 °C, a maximum final pressure of 25.1 MPa and a residence time of 30 min. The moisture content of the raw peat was approximately 90 wt.%. Raw peat was hydrothermally upgraded without the addition of water in the laboratory scale. The yield of the solid products was between 53.0 and 99.7 wt.% and the effective calorific value of hydrothermally dewatered peat was between 17,290 and 29,209 kJ/kg following hydrothermal upgrading. In addition, the oxygen content in the solid product was varied from 38.4 to 15.6 wt.% after upgrading, while the carbon content from 55.2 to 77.8 wt.%. The hydrothermally upgraded peat fuel product also had an equilibrium moisture content of 2.3 wt.% and a maximum equilibrium moisture content of 17.6 wt.%. Upgraded peat is characteristically resistant to moisture adsorption at high humidity, which makes it promising for fuel based combustion. The change in the carbon-functional groups and their properties, as determined by FTIR and ¹³C NMR, are discussed in terms of the hydrothermal upgrading and dewatering process.     

Post-hydrothermal treatment of hydrothermal electrodeposited CaHPO4 on C/C composites in sodium silicate-containing solution at various temperatures

Direct deposition of hydroxyapatite (HA) coatings on carbon/carbon(C/C) composites through hydrothermal electrochemical deposition (HED) were limited by the poor bonding strength. To overcome this problem,in this work, CaHPO₄ (monetite) coating was firstly deposited on C/C using HED, and then converted into HA coating in a sodium silicate–containing solution by post-hydrothermal treatment. Effects of post-treatment temperatures on the chemical composition, structure, and bonding strength of the coatings were investigated. The results showed that obtained monetite showed a compact microstructure, and could react with the solution to produce a well-crystallized HA as well as amorphous silicate which contained some calcium and sodium ions. All the coatings were composed of rod-like crystals. The diameter of these crystals increased when the post-hydrothermal temperature was changed from 110?℃ to 140?℃, and then decreased at 155?℃. The Si contents and the adhesive strength of the HA coatings showed a similar temperature dependence to the crystal size of the HA. 140?℃ is determined to the optimal treatment temperature, at which the HA coating reached the highest critical load of 24.02?N, corresponding to the shear strength of 82.83?MPa. The bioactivity of the HA coating on C/C increased with the increasing post-treatment temperature.     

Applications of hydrothermal electrolysis for conversion of 1-butanol in wastewater treatment

Hydrothermal electrolysis of organic compound in the presence of electrolyte was conducted for a woody biomass model compound. The reaction behavior of 1-butanol as a woody biomass model compound was studied in subcritical conditions at 200-250 °C and 8-12 MPa with a batch autoclave. The autoclave volume was 500 mL and equipped system with agitation stirrer, electric current control, electric heating and temperature control and a pressure gauge. The chemical species in aqueous products were identified by gas chromatography mass spectrometry (GC-MS) and quantified using gas chromatography flame ionization detector (GC-FID). The gaseous products were analyzed by gas chromatography with a thermal conductivity detector (GC-TCD). The effects of reaction temperature, pressure and applied constant current on the conversion process of 1-butanol were presented. The main products from the conversion of 1-butanol were butanal, butyric acid, hydrogen and carbon dioxide. Additionally, the values of reaction rate constant for butanal and butyric acid formation were calculated at 200 and 250 °C by kinetic study.     

Biocatalytic production of ricinoleic acid from castor oil: augmentation by ionic liquid

Abstract

In present study involving castor oil hydrolysis catalyzed by porcine pancreas lipase, organic solvent, and ionic liquid were applied to augment production of ricinoleic acid. Toluene was the best organic solvent (30.18% hydrolysis in 2?h). In presence of 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF₆]), an ionic liquid, the optimal conditions were, 0.12?g ionic liquid/g oil, 4?mg enzyme/g oil, 2?g buffer/g oil, pH of 8, and 2.5?h. Under this condition, ricinoleic acid recovery was 43.41 and 52% at 25?°C and 35?°C, respectively. Organic solvent concentration, enzyme concentration, buffer concentration and time had significant impacts on lipase catalyzed hydrolysis in the presence of organic liquid; whereas, pH and speed remained insignificant. In hydrolysis involving ionic liquid, time had most important effect on ricinoleic acid production. Interaction between enzyme and buffer concentration was most significant. Interactions of ionic liquid concentration with all other variables were also significant besides buffer concentration–time interaction.     

Furfural production by acid hydrolysis and supercritical carbon dioxide extraction from rice husk

The aim of this research was to study the effect of furfural production from rice husk by hydrolysis accompanying supercritical CO₂ (SC-CO₂) extraction. The two-level fractional factorial design method was used to investigate the production process carried out with respect to furfural yield. The process variables are temperature range of 373–453 K, pressure 9.1–18.2 MPa, CO₂ flow rate 8.3 × 10⁻⁵–1.7 × 10⁻⁴ kg/s (5–10 g/min), sulfuric acid concentration 1 to 7 (%wt) and ratio of liquid to solid (L/S) 5 : 1 to 15 : 1 (vol/wt). The results obtained from the experimental design showed that increasing temperature, pressure, CO₂ flow rate and sulfuric acid concentration but decreasing ratio of liquid to solid would improve furfural yield. Moreover, furfural production by two-stage process (pre-hydrolysis and dehydration) can improve furfural yield further to be around 90% of theoretical maximum.     

The effect of amino acids and amino acid analogues on growth of an obligate methanotroph,Methylosinus trichosporium OB3b

The sensitivity of the obligate methanotroph, Methylosinus trichosporium OB3b to a number of amino acid analogues and amino acids has been examined. Sulphaguanidine (5 μg ml^?1) norleucine (100 μg ml^?1) m-fluorophenylalanine (50 μg ml^?1), p-fluorophenylalanine (50 μg ml^?1) and S2-aminoethyl-C-cysteine (1000 μg ml^?1) inhibited growth. Proline, threonine, methionine and lysine (2–4 μg ml^?1) also inhibited growth, but arginine and leucine at similar concentrations had no effect. Attempts were made to isolate amino acid analogue resistant mutants, which would be expected to overproduce amino acids. Two approaches were made, selection of spontaneous and induced mutants in plate culture, and selection of a spontaneous mutant during growth in continuous culture under selective conditions, but no mutants were obtained. Possible reasons for failure to obtain such mutants are discussed.     

Effect of processing conditions on organics in wastewater from hydrothermal dewatering of low-rank coal

A study was carried out into the effects of processing conditions on the nature and amounts of organics released into wastewater from hydrothermal dewatering (HTD) of low-rank coal. Processing conditions examined included temperature, residence time, water to coal ratio in the slurry, slurry loading, and coal lithotype. High temperature and pressure treatments of low-rank coal slurries were used to simulate the HTD process. It was found that the extent of extraction of organics during HTD processing depended on the coal lithotype and increased with increasing temperature, residence time, and the proportions of steam and water present during processing. For a constant residence time, the concentration of organics in the wastewater increased exponentially with temperature over the temperature range 250-350 °C. A maximum level of approximately 7 g/l (expressed as TOC) of organics was observed following processing at 350 °C. Hot filtration of the coal slurry produced a higher organics loading compared to that found in wastewater obtained at low temperature.     

Removal of copper (II) and phenol from aqueous solution using porous carbons derived from hydrothermal chars

The feasibility of hydrothermal char (HTC), a byproduct from biomass hydrothermal liquefaction for bio-oil production, as raw material for preparation of porous carbons was investigated in the present study. The resultant HTC-derived porous carbons were characterized and utilized as adsorbents for copper (II) and phenol removal from aqueous solution. Compared with porous carbons using pyrolytic char as precursor, the HTC-derived porous carbons exhibited unique textural features, e.g., narrow pore size distribution, high surface area and large pore size. In addition, FT-IR analysis confirmed that substantial amount of ketene groups existed on the surface of the HTC-derived porous carbons. As the adsorbents, the copper (II) adsorption onto HTC-derived carbons was strongly affected by the pH value of the solution in comparison with phenol adsorption. The carbons derived from pinewood and rice husk HTC exhibited high adsorption capacity of 83.88 and 39.30 mg/g for phenol and 25.18 and 22.62 mg/g for copper (II), respectively. The adsorption data for copper (II) and phenol onto the carbon adsorbents could be well described by Langmuir and Freundlich models. In comparison with pinewood sawdust HTC-derived carbon, the adsorption onto rice husk HTC-derived carbon preferentially followed Freundlich model due to the presence of silica on the surface.     

Enzymatic production of Xylooligosaccharide from selected agricultural wastes

Four different agricultural wastes, namely tobacco stalk (TS), cotton stalk (CS), sunflower stalk (SS) and wheat straw (WS) were tested for the production of Xylooligosaccharide (XO). XO production was performed by enzymatic hydrolysis of xylans which were obtained by alkali extraction from the agricultural wastes. Depending on the source, it was found that these four agricultural wastes contained different amount of xylan, cellulose and lignin and the xylan obtained from these source contained different amount of sugar and uronic acid. The highest amount of arabinose was in xylan from WS while the other xylans mainly had xylose and small amount of glucose. Different xylanase preparations were evaluated for production XO from these xylan sources. Aspergillus niger xylanase produced lower amount of XO from wheat straw xylan (WSX) than cotton stalk xylan (CSX), sun flower xylan (SSX) and tobacco stalk xylan (TSX) while Trichoderma longibrachiatum xylanase hydrolyzed highly branched WSX better. The HPLC analysis of the hydrolysis products indicated that depending on structure and composition of xylan, A. niger xylanase produced less amount of xylose than T. longibrachiatum xylanase, and the hyrolysis product of A. niger xylanase contained different amount of oligosaccharides (X2 > X3 > X4 > X5 > X6, >X6). Regardless of the structural differences of the xylan types presented in this paper, all xylans generated XO with different degree of polymerization (DP), but the DP of XO depended on the enzyme specificity and the structure of substrate.