用正交设计法探讨纤维素水解的最佳实验条件

本文总结归纳出13个影响纤维素水解的因素,用正交实验设计法找出纤维素水解的最佳实验条件。

溶解浆生产技术现状及研究进展

概述了目前国内外溶解浆的生产技术现状及研究进展,介绍了由纸浆直接制备溶解浆的生产技术,从而提高相关产业的竞争力,实现传统工业的发展和变革。

白内障超声乳化术后前房膜形成的危险因素(英文)

目的:探讨白内障超声乳化术后前房膜形成的危险因素。方法:对1356例行白内障超声乳化+单片式PMMA人工晶体植入术患者进行前瞻性研究。假性囊膜剥脱综合症,核硬度,瞳孔大小,超声时间,实际超声时间,系统性疾病,术中并发症(囊膜撕裂,悬韧带断裂,后囊破裂伴玻璃体丢失),IOL植入位置和术后并发症(眼内压变化,粘连形成)作为膜形成的危险因素分析。结果:观察到111例患者(8.1%)术后出现伴有膜形成的纤维素性前葡萄膜炎。膜形成平均时间是术后第2d(术后第1～7d),膜存在持续时间平均为5.2d(1～48d)。在膜形成病例中,+4级核病例占45%,而在无膜形成病例中仅为13.5%,差异具有显著统计学意义(P<0.05)。在膜形成组,平均超声时间为2.4min,平均实际超声时间为32.8s,而无膜形成组分别为1.8min和22.1s。这两项参数在膜形成组均明显较长(P<0.05)。在膜形成组中,出现后囊破裂伴玻璃体丢失和IOL睫状沟植入者占33%,而无膜形成组为11%(P<0.05)。其他危险因素在膜形成组和无膜形成组中的比较无统计学意义。在术后第1d和第7d,平均最佳矫正视力(Snellen视力表)在膜形成组分别为0.2和0.4,无膜形成组为0.4和0.6(P<0.05)。但术后3mo,平均最佳矫正视力在膜形成组和无膜形成组中结果相似(分别为0.8和0.9)。结论:晶状体核硬度较高,较长超声时间和实际超声时间,术中后囊破裂是术后前房纤维膜形成的明显相关性危险因素。

Insulin resistance and hepatitis C

Insulin resistance is the major feature of the metabolic syndrome and depends on insulin secretion and insulin sensitivity. In chronic hepatitis C, insulin resistance and type 2 diabetes mellitus are more often seen than in healthy controls or chronic hepatitis B patients. Hepatitis C virus （HCV） infection promotes insulin resistance, mainly by increased TNF production together with enhancement of suppressor of cytokine （SOC-3）; both events block PI3K and Akt phosphorylation. Two types of insulin resistance could be found in chronic hepatitis C patients＇. ＂viral＂ and ＂metabolic＂ insulin resistance. Insulin resistance in chronic hepatitis C is relevant because it promotes steatosis and fibrosis. The mechanisms by which insulin resistance promotes fibrosis progression include： （1） steatosis, （2） hyperleptinemia, （3） increased TNF production, （4） impaired expression of PPARy receptors. Lastly, insulin resistance has been found as a common denominator in patients difficult-to-treat like cirrhotics, overweight, HIV coinfected and Afro-American. Insulin resistance together with fibrosis and genotype has been found to be independently associated with impaired response rate to peginterferon plus ribavirin. Indeed, in genotype 1, the sustained response rate was twice （60%） in patients with HOMA ≤ 2 than patients with HOMA 〉 2. In experiments carried out on Huh-7 cells transfected by full length HCVRNA, interferon alpha blocks HCV replication. However, when insulin （at doses of 128 μU/mL, similar that seen in the hyperinsulinemic state） was added to interferon, the ability to block HCV replication disappeared, and the PKR synthesis was abolished. In summary, hepatitis C promotes insulin resistance and insulin resistance induces interferon resistance, steatosis and fibrosis progression.

Numerical Approach to the Mechanism of Cellulose Pyrolysis

A detailed mechanism analysis of cellulose pyrolysis was carried out according to the previous experimental results. On the basis of the Brodio-Shafizadeh model, a modified two-stage model was proposed to simulate the formation and decomposition of active cellulose (AC) and several main organic compounds, such as levoglucosan (LG), hydroxyl-acetaldehyde (HAA), acetol and furfural etc. During pryolysis, the temperature rise of cellulose can be divided into three stages. In the second stage, cellulose undergoes a main decomposition process in which the reaction temperature remains rather low because of the endothermic cracking of glucosidic bond of AC during the formation of LG. The components density of bio-oil, including LG and other competitive compounds, increased rapidly with the increase of temperature during the first stage. However, in the main decomposition process, LG density in bio-oil had an obvious decrease, while the competitive products appeared to increase gradually, which means the ring-opening and reforming reaction of pyranoid ring are superior to LG formation in high temperature.The secondary reaction of volatile components occurs largely in gaseous phase rather than in the solid phase. Short residence time of volatile materials in high temperature region will be advantageous to a high production of LG,which may otherwise decompose quickly under high temperature. An optimum yield of LG could be obtained when radiant source temperature is in the range of 730---920K and gas residence time is less than 1 s. In addition, the reaction temperature has a stronger effect than gas residence time on the formation of HAA, acetol, formaldehyde and furfural etc.

Kinetics of reductive leaching of manganese oxide ore using cellulose as reductant

The kinetics of reductive leaching of manganese from a low-grade manganese oxide ore were studied using cellulose as reductant in dilute sulfuric acid medium.It was found that when the stirring speed was higher than 200 r/min,the effect of gas film diffusion on manganese extraction efficiency could be neglected,and the kinetic behavior was investigated under the condition of elimination of external diffusion influence on the leaching process.Effects of leaching temperature,mass ratio of cellulose and ore,and the sulfuric acid concentration on manganese extraction efficiency were discussed.The kinetic data were analyzed based on the shrinking core model,which indicated that the leaching process was dominated by both ash layer diffusion and chemical reaction at the initial stage,with the progress of leaching reaction,the rate-controlling step switched to the ash layer diffusion.It was also concluded that the sulfuric acid concentration had the most significant influence on the leaching rate,the reaction orders with respect to the sulfuric acid concentration were 2.102 in the first 60 min,and 3.642 in the later 90 min,while the reaction orders for mass ratio of cellulose and ore were 0.660 and 0.724,respectively.An Arrhenius relationship was used to relate the temperature to the rate of leaching,from which apparent activation energies were calculated to be 46.487 kJ/mol and 62.290 kJ/mol at the two stages,respectively.Finally,the overall leaching rate equations for the manganese dissolution reaction with cellulose in sulphuric acid solution were developed.The morphological changes and mineralogical forms of the ore before and after the chemical treatment were discussed with the support of SEM and XRD analyses.

Enzymatic Hydrolysis of Cellulose with Different Crystallinities Studied by Means of SEC-MALLS

The reactions of exo-cellulase （cellobiohydrolase, CBH） and endo-cellulase （endoglucanase, EG） were investigated by analyzing the insoluble residues of microcrystalline cellulose （MCC） and filter paper cellulose （FPC） during enzymatic hydrolysis. Molecular parameters including molecular weight and its distribution, degree of polymerization, and radii of gyration were measured by size exclusion chromatography coupled with multi-angle laser light scattering. No significant change in MCC chains was found during the whole reaction period, indicating that CBH digestion follows a layer-by-layer solubilization manner. This reaction mode might be the major reason for slow enzymatic hydrolysis of cellulose. On the other hand, the degree of polymerization of FPC chains decreases rapidly in the initial reaction, indicating that EG digestion follows a random scission manner, which may create new ends for CBH easily. The slopes of the conformation plots for MCC and FPC increase gradually, indicating stronger chain stiffness of cellulose during hvdrolvsis

Preparation of Waterborne Nanoscale Carbon Black Dispersion with Sodium Carboxymethyl Cellulose

Waterborne nanoscale carbon black dispersion （NCBD） was widely used in inkjet printing, spun.dyeing fibers and coloration fabrics. In this paper, NCBD was prepared using sodium carboxymethyl cellulose （CMC） as dispersant. Effects of CMC viscosity, ultrasonic time and oxidation with hydrogen peroxide on carbon black （CB） particle size were discussed. The results showed that CB particle size decreased by mechanical agitation while it Increased by ultrasonic with the increase of CMC viscosity. Uitrasonk is a more effective method to disperse CB particles than that of mechanical agitation. CB particle size lbviously decreased with itcreasing ultrasonic time and arrived at about 160 nm for 60min.In addition,oxidation with 2 mol/L of H2O2 and 0.2wt% of CMC300 reduced CB particle size to 160nm at 90℃ for 2.5h.

Techniques Optimization of Combined Enzymatic Hydrolysis on Brewers＇ Spent Grain from Novozymes

Purpose： To extract protein, decrease the cellulose and facilitate the digestion and absorption of brewers＇ spent grain by animal. Topic： Discuss and optimize the hydrolysis conditions of the combined enzymatic hydrolysis by Novozymes. Method： The fresh brewers＇ spent grain was firstly dried, smashed and sifted. Then as indicators of the protein extraction rate in the enzyme solution and the content of cellulose in the index, the parameters of enzymatic hydrolysis, such as the solid-liquid ratio, reaction temperature, pH, enzyme dosage and reaction time, were investigated in detailed. After hydrolysis, the brewers＇ spent grain was put in the boiling water bath for inactivation for 15 minutes, and centrifuged, the supernatants were volume to 100 mL and the protein content was measured. After the precipitate was dried, the cellulose content was also measured. Achievements： The optimized conditions were with temperature of 50 ℃, pH 6.5, enzyme amount of 30 mg for Novozymes enzyme and 2.5 h for reaction time. Under these conditions, the protein extraction rate in the enzyme reaction reached 41.82%, and the cellulose content reached 13.90%, the degradation rate of cellulose was 18.86%.

Study on the Treatment of Cellulosic Ethanol

Wastewater from the production of cellulosic ethanol was treated by the processes of internal micro-electrolysis method ＋ABR＋UASB ＋MBR. The results of running indicated that, when COD is 12000 mg/L and HRT of UASB is 48 h, the COD removal rate reaches 72% and HRT of MBR is 20 h, COD removal rate is between 80.8% and 87.5%. The effluent COD concentration stabilized at 301- 537 mg/L, it indicates that the MBR system has a strong ability to resist impact load.

Production of D-p-Hydroxyphenylglycine from DL-5-p-Hydroxyphenyl Hydantoin by Immobilized Pseudomonas Putida Cells in a Hollow Fiber Membrane Bioreactor

An immobilized cell membrane bioreaction system was developed to promote cell stability. The hollow fiber membrane bioreactor with immobilized Pseudomonas putida cells, operating in continual repeated batch operation mode was used for producing D-p-hydroxyphenylglycine from DL-5-p-hydroxyphenyl hydantoin. The concentration of N-carbamyl-D-p-hydroxyphenylglycine and D-p-hydroxyphenylglycine in the efflux was analyzed by high performance liquid chromatography at different intervals.

Synthesis and Surface-Active Properties of Carboxymethylcellulose Esters Obtained by Microwave Assisted Transesterification of Vinyl Laurate

Polymeric biosurfactants were prepared by the transesterification reaction between vinyl laurate （VILA） and carboxymethylcellulose （CMC）. The reaction was performed in two different reaction media （（A） DMF/pTSA and （B） DMF/K2CO3） at various reaction conditions and using microwave radiation with controlled power as heating source. The obtained water-soluble VILA-CMC derivatives were characterized by FT-IR spectroscopy and their surface-active properties evaluated. All derivatives showed a very low esterification extent and moderate surface tension lowering effect. Nevertheless, they exhibited significant emulsifying efficiency comparable to that of the synthetic surfactant, Tween 20. The results suggested that suitable surface-active VILA-CMC derivatives can be prepared under microwave heating at low microwave power and reaction times in the range of few minutes, which represents a great advantage in comparison to transesterification reactions lasting up to 6 h at conventional heating.

Recyclable nanocellulose-confined palladium nanoparticles with enhanced room-temperature catalytic activity and chemoselectivity

We describe the synthesis of even-dispersed palladium nanoparticles(Pd NPs)confined within a cellulose nanofiber(CNF)matrix for developing a high-performance and recyclable catalyst.The CNF matrix was composed of CNF-assembled mesoporous nanosheets and appeared as soft and hydrophilic foam.Ultrafine Pd NPs(∼6 nm)with high-loading(9.6 wt%)were in situ grown on these mesoporous nanosheets,and their dense spatial distributions were likely to generate nano-confinement catalytic effects on the reactants.Consequently,the CNF-confined Pd NPs(CNF-Pd)exhibited an enhanced room-temperature catalytic activity on the model reaction of 4-nitrophenol hydrogenation with a highest rate constant of 8.8×10^−3 s^−1 and turnover frequency of 2640 h The CNF Pd catalyst possessed good chemical stability and recyclability in aqueous media which could be reused for at least six cycles without losing activity.Moreover,chemoselective reduction of 3 nitrostyrene was achieved with high yield(80%–98%)of 3-aminostyrene in alcohol/water cosolvent.Overall,this work demonstrates a positive nanoconfinement effect of CNFs for developing stable and recyclable metal NP catalysts.

Lysyl oxidase promotes bleomycin-induced lung fibrosis through modulating inflammation

Enzymes involved in collagen biosynthesis, including lysyl oxidase （LOX）, have been proposed as potential therapeutic targets for idio- pathic pulmonary fibrosis. LOX expression is significantly upregulated in bleomycin （BLM）-induced lung fibrosis, and knockdown of LOX expression or inhibition of LOX activity alleviates the lung fibrosis. Unexpectedly, treatment of the mice with LOX inhibitor at the inflammatory stage, but not the fibrogenic stage, efficiently reduces collagen deposition and normalizes lung architecture. Inhibition of LOX impairs inflammatory ceU infiltration, TGF-β signaling, and myofibroblast accumulation. Furthermore, ectopic expres- sion of LOX sensitizes the fibrosis-resistant Balb/c mice to BLM-induced inflammation and lung fibrosis. These results suggest that LOX is indispensable for the progression of BLM-induced experimental lung fibrosis by aggravating the inflammatory response and subse- quent fibrosis process after lung injury.

Enhancing polyphenol extraction from unripe apples by carbohydrate-hydrolyzing enzymes

The effects of process variables such as enzyme types, enzyme ratio, reaction temperature, pH, time, and ethanol concentration on the extraction of unripe apple polyphenol were investigated. The results indicated that Viscozyme L had the strongest effect on polyphenols extraction and was selected to study the polyphenol composition. The ratio of enzyme （Viscozyme L） to sobstrate （2 fungal beta-glucanase units （FBG）） at 0.02, reaction at pH 3.7, 50℃ for 12 h, and ethanol concentration of 70% were chosen as the most favorable extraction condition. Total phenolic content （TPC）, reducing sugar content （RSC）, and extraction yield increased by about 3, 1.5, and 2 times, respectively, compared with control. The contents ofp-coumaric acid, ferulic acid, and caffeic acid increased to 8, 4, and 32 times, respectively. The enzyme-aided polyphenol extraction process from unripe apples might be applied to food industry for enhancing bioactive compound production.