Advanced Materials Research Vols. 550-553

Abstract: In this paper, the cross-linking injection hydrogel were synthesized by EDC crosslinker and Carboxymethyl chitosan (CMCS)/Human-like collagen (HLC). Cytotoxicity was assessed by Methylthiazolydiphenyl-tetrazolium bromide (MTT) assay which indicated that the hydrogels was non-toxic to the BHK21 cell .Chondrocyct-encapsulation of this hydrogel were studied in order to asses the cells compatibility of the injection gel. The result showed that the material has no cytotoxicity to the cells and promoted cell adhesion and proliferation. Injected those hydrogels into mice subcutaneous , the following parameters were evaluated: inflammatory response, vascularization, new hypoderm generation. After 2,4,12,and 24 weeks of healing, the rats were sacrilifced suggested that gels in animals did not induce inflammation obvious, vessel bestrid the material after 4 weeks injection, new hypoderm generated in 12 weeks and packaged the hydrogels after 24 weeks. Consequently the gels are promised for the application in the biomaterials area.

Abstract: The adsorption properties of sodium lignosulfonate (SL) on Al₂O₃ particles under different pH values have been investigated. Results show that at low pHs, SL adsorbs on the Al₂O₃ particles in the form of aggregate as dosage of SL increases; at high pHs, the adsorption is approximately monolayer coverage. With pH values ranging from 3 to 11, the adsorption results are found to be not significantly affected by the addition of urea, ruling out the hydrogen bond as the controlling factor. The paper demonstrates that the main driving force of adsorption is considered as the synergistic effect of electrostatic and hydrophobic interactions when pH pHIEP with additives of Na₂SO₄ and NaCl.

Abstract: Biosurfactants are natural surface-active compounds mainly synthesized by microorganisms, which have distinct advantages like no secondly pollution and friendly to environment compared with chemical surfactants. With the development of modern biological technology, biosurfactants have been shown a variety of potential applications, including medicine, agriculture, oil production and environmental remediation, so it has already caused many researchers a strong interest in the production of biosurfactants making use of biological technology. A review is made from the isolation of biosurfactants. In addition, on the foundation of the analysis,several suggestions about the development of biosurfactants are proposed.

Abstract: The correlations between the phylogenetic similarity and original geographical sites of L. ferriphilum were evaluated on the basis of 16S rDNA sequence analysis. Results indicated that all of L. ferriphilum strains in this work may be classified into three phylogenetic groups, and there were some certain links between phylogenic similarity and the mineralogical characteristics. Furthermore, structural analysis of 16S rDNA sequences suggested that nucleotide variables (signature sites) were not randomly distributed. Of 23 signature sites detected, 17 positions were found in the first 600 bp from 5' terminal except position 1020, 1022, 1023, 1147, 1155 and 1277. Interestingly, 13 positions of them were found in the V6 region. Thus, the secondary structure and minimal free energy were determined in the V6 region among strains of three phylogenetic groups. The above results may be very useful in helping to screen bioleaching microorganisms with great application prospect and discerning the microevolutionary mechanisms of species formation.

Abstract: In this study, the high purity tetracalcium phosphate (TTCP) was prepared conveniently after studying the effect of cooling method on the purity of TTCP. The influence of liquid-to-powder (L/P) ratio on the properties of self-setting silk fibroin/calcium phosphate composites was studied. The results showed that the temperature of the furnace had a significant influence on the purity of TTCP when samples were removed from the furnace. Whether using N2 or not had no obvious effect on the purity of TTCP when the temperature declined from 1500°C to 1300°C. The setting time of composites became longer with the increase of L/P ratio in a range 0.32 - 0.39 ml/g, but all less than 15min. The injectability of the composites improved significantly as the L/P ratio increased. The compressive strength of composites reached maximum at the L/P ratio of 0.34 ml/g. The compressive strength decreased with the increase of L/P ratio greater than 0.34ml/g. The L/P ratio had no significant effect on the structure of the composites and the rod-like crystal of hydroxyapatite appeared in all the hardening-body of composites.

Abstract: In this paper, calcium sulfate hemihydrate (CSH) was added into silk fibroin/calcium phosphate (SF/CP) composites. The macropores formed by the SF was connected by micropores formed from rapid degradation of CSH, so that the structure of the composites is more close to the natural bone. The results indicated that the range of pore sizes around 30 - 308 microns were formed in the composites by SF. Compared to SF/CP composites without CSH, the injectability decreased, but the rate were both above 90%; the setting time increased, but were both less than 16min; the porosity increased. When the proportion of CSH was greater than 10%, the morphology of the product of setting reaction, i.e. the hydroxyapatite (HA) crystals, was influenced. When the proportion of CSH was less than 10%, the HA crystals appeared to be needle-like and plate-like crystals. When the proportion of CSH was greater than 10%, HA crystals were needle-like. The added amount of CSH had significant effects on compressive strength and work-of-compressive. The compressive strength and work-of-compressive decreased with increasing of CSH content in the composites.

Abstract: Kinetic models are proposed for the 2KGA batch production from rice starch hydrolysate containing 162 g/L of glucose by Pseudomonas fluorescens AR4. The models include terms accounting for both substrate and product inhibitions. Experimental data collected from the batch fermentations were used to estimate parameters and also to validate the models proposed. The growth of Ps. fluorescens could be expressed by a Logistic model wihout incorporating inhibitions of glucose and organic acids accumulated in the culture broth. The Luedeking–Piret model was able to describe the 2KGA formation as the fermentation proceeded with a mixed-growth-associated pattern. In all cases, the model simulation matched well with the experimental observations, which made it possible to elucidate the fermentation characteristics of Ps. fluorescens AR4 during efficient 2KGA production from glucose.

Abstract: The degradation law of straw lignin by white-rot fungi was studied. The adding amount of synthetic medium, the inoculum size and the temperature were investigated by experiment of single factor and orthogonal experiments. In the 6.5g straw fermentation medium, the optimum process conditions of degrading straw lignin by white-rot fungi were as follows: the adding amount of synthetic medium was 14mL; the inoculum size was 0.8mL; the temperature was 35°C. Through the additional experiment, degradation rate of the lignin was 49.50%; the degradation rates of cellulose and hemicellulose were 38.41% and 47.88%, respectively.

Abstract: A pilot-scale modified SBR process was investigated to treat urban wastewater. The average NH₄⁺-N efficiency removal was 98 %. The average TN removal efficiency was 52 %. The average effluent NH₄⁺-N was 0.34 mg/L. The average effluent TN was 12 mg/L. The average effluent phosphorus was 0.75 mg/L. The average effluent COD was 35 mg/L. The result showed that the ratio of influent NH₄⁺-N /TN was equal approximately to TN removal efficiency. The TN removal ratio was decided by the influent NH₄⁺-N. The long anaerobic time was benefit to the nitrogen removal. The optimal anaerobic time should be set at 1 hour.

Abstract: The preparation technology of tilapia protein hydrolysates by building single factor test and response surface methodology (RSM) were defined. The effect of hydrolysis temperature, pH, the additive quantity of Alcalase, the ratio of liquid-to-solid on degree of hydrolysis (DH), TCA-soluble nitrogen index (TCA-NSI) and yield of acid-solubility peptide (YASP) by regression model was obtained by response surface analysis. Regression model indicated that the optimal condition hydrolyzed animal protein of tilapia meat by proteinase was described as following：hydrolysis temperature 54.30°C, pH 8.77, the additive quantity of Alcalase 2.4L was 3702U/g, the ratio of liquid-to-solid was 3.06, hydrolysis time 1 hour. Under such conditions, the DH(%), TCA-NSI(%) and YASP(%) reached 33.63%, 22.10%, 64.55%, respectively. Experiment result showed that the predictive value and experimental value was small deviation and indicated that regression model was reasonable and reliable.