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.     

Microwave-enhanced hydrolysis of poultry feather to produce amino acid

Poultry feather was hydrolyzed at relatively mild high temperature ranging from 433 to 473 K and autogenous pressure by intensification of microwave heating. The hydrolysate mainly contains arginine, alanine, threonine, glycine, praline, serine, glutamic acid, aspartic acid, cystine and tyrosine, which corresponds with hydrochloric acid catalytic hydrolysis. Based on the orthogonal experimental result, the total yield of amino acid attains about 54.72% with feather containing about 71.83% keratin at optimum reaction condition of temperature 473 K, time 20 min and weight ratio of water/feather 37.5. The high yield of amino acid and high efficiency of hydrolysis indicate that the microwave has better intensification on hydrolysis comparing with traditional strong acid catalytic or sub-critical hydrolysis. The apparent activation energies (E_a) are 85.12 and 63.00 kJ/mol as to the hydrolysis of feather and the degradation of produced amino acid with consecutive pseudo-first-order reaction kinetic model, and the great decrease of the values comparing with non-microwave heating should be the reason of the enhanced effect of microwave.     

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.     

Improvement in hydrogen production from hard-shell nut residues by catalytic hydrothermal gasification

The hydrothermal gasification of some hard-shell nut residues (hazelnut, walnut and almond shells) was performed in a batch type reactor at temperature and pressure ranges of 300–600 °C and 88–405 bar, respectively. The biomass samples were converted into gaseous product (hydrogen, carbon dioxide, methane, carbon monoxide and C₂–C₄ compounds), aqueous product (carboxylic acids, furfurals, phenols, aldehydes and ketones) and solid products after hydrothermal gasification. Hydrogen production was improved by using natural mineral catalysts (Trona, Dolomite and Borax). The activity of selected natural mineral catalysts in hydrothermal gasification can be ordered as being Trona [Na₃(CO₃)(HCO₃)·2H₂O] > Borax [Na₂B₄O₇·10H₂O] > Dolomite [CaMg(CO₃)₂]. The most effective catalyst was found to be Trona at 600 °C leading enhancement in hydrogen yields (mol H₂/kg C in biomass) for hazelnut, walnut and almond shells as 82.4%, 74.1% and 42.4%, respectively.     

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.     

Surface treatment methods for mitigation of hydrothermal ageing of zirconia

Hydrothermal ageing of zirconia ceramics (tetragonal-to monoclinic phase transformation in the presence of humidity) is highly sensitive to the surface characteristics. Thus chemical modifications of the surfaces over a few microns may be a good way to mitigate ageing without affecting bulk mechanical properties. Here, the efficiency of different post-sintering thermal treatments in powder beds of different compositions to prevent or slow down hydrothermal ageing of 3Y-TZP is tested. The microstructure, ageing kinetics at different temperatures and mechanical properties of the treated samples are then evaluated.Treatments with 12Ce-TZP proved to be the most efficient to limit ageing at 134 °C while keeping good mechanical properties. However, this is accompanied by a decrease of the activation energy of ageing, thus by an acceleration of ageing at lower temperature. These results also show that the activation energy of ageing is material-dependant, thus should be ascertained for every developed zirconia-based ceramic.     

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.     

Effect of crystal structures on nucleation mechanism in hydrothermal synthesis of MZrO3 (M=Ba,Sr, Ca)

Hydrothermal method is widely used in the synthesis of perovskite-type oxides, whereas few studies are reported for the nucleation mechanism, so that the relationship between the crystal structures and reactive activities of reactants and products is still unknown. Herein, the reaction processes are analyzed on the basis of XRD, SEM and Raman characterizations, and the nucleation mechanism is investigated for the hydrothermal synthesis of MZrO₃ (M = Ba, Sr, Ca). We propose that the negative charged cyclic tetramer complexes [Zr₄(OH)₈(OH)₁₆]^8- form in the hydrothermal reaction, which play major roles in the nucleation process. The tetramer complexes continually dehydrate and condensate to form substructural units composed of alkali-earth ions and 6-fold Zr tetramers; substructural units further dehydrate and distort to form perovskite structures. The reactive activation energy increases with the decreasing of M²⁺ (M = Ba, Sr, Ca) ionic radius because the incorporation of smaller A site ions in the perovskite structure is accompanied by greater rotation and distortion of the ZrO₆ octahedra, leading to the decrease of reactive activity accordingly. In a word, the proposed nucleation mechanism in this paper is of great significance for the study of perovskite.     

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。     

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.     

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.     

An ultrasonic-ionic liquid process for the efficient acid catalyzed hydrolysis of feather keratin

A novel efficient method for hydrolyzing feather keratin using an ultrasonic-ionic liquid coupling process has been developed, with reaction conditions optimized using response surface analysis of data obtained from single factor optimization studies. Ultrasonic irradiation(225 W power) of feathers in 8.4 mol·L~(-1) hydrochloric acid containing 1-butyl-3-methylimidazolium chloride as a cosolvent at 80 °C for 1.4 h, followed by heating at 110 °C for 8.3 h, resulted in hydrolysis of their keratin component in an excellent 83.1% yield. Compared with previous methods, this new method employs reduced amounts of hydrochloric acid, shorter reaction time, and affords amino acid hydrolysis products in higher yield.     

Effect of heat treatment on the synthesis of hydroxyapatite from Indian clam seashell by hydrothermal method

Hydroxyapatite (HA) powder has been successfully synthesized from low-cost Indian clam seashells by using hydrothermal method. The mixture of tri-calcium phosphate [Ca₃(PO₄)₂], heat-treated ball-milled clam seashell, and demineralized water are heat-treated at several temperatures (700 °C, 800 °C, 900 °C, 1000 °C, and 1100 °C) for various time periods (1 h, 2 h, and 3 h) to perform the hydrothermal reactions. The phases and microstructure of the solid-state reaction products are analyzed through X-ray diffraction (XRD) method and field emission scanning electron microscopy (FESEM) respectively. The crystallite size of all the synthesized powders is calculated by using Scherrer's model. Mainly HA phase is obtained in all the different reaction products. However, these HAs are found to be non-stoichiometric in nature. As per the literature, non-stoichiometric HA is a more biologically active material compared to the stoichiometric one. Almost pure HA is formed with any selected reaction temperature applied for 2 h time duration. The crystallinity and Ca/P ratio of the synthesized pure HA are estimated by using standard model and energy-dispersive X-ray spectroscopy (EDS) analysis, respectively. The highest amount of near stoichiometric crystalline HA has been obtained at 900 °C of reaction temperature applied for 2 h time duration. With raising reaction temperature, the grain size of pure HA is found to be increased. Needle/rod shaped nano grains are noticed to form at lower reaction temperature whereas; beyond 1000 ^oC of temperature globular/spherical shaped grains are also observed to form. At 3 h reaction time agglomeration of grains is found to occur in all the synthesized powders.     

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.     

超(亚)临界水热法处理有机废物的研究进展

介绍了超（亚）临界水的特殊性质,综述了超（亚）临界水热法有机废物氧化和水解制有机酸、聚合物降解以及纤维性有机废物降解的应用进展,着重评述了超（亚）临界水热法生物质气化尤其是炭、碱和金属3种催化剂催化气化制取H2的发展现状,并展望了超（亚）临界水热法的发展前景。