Selection and Study of High-yield Aerobic Strains of Treating the Closed Circulation Wastewater for Regenerated Fiber

Efficient and reliable removal of cellulose,hemicellulose and lignin,that are the major organic pollutants in the wastewater from regenerated fiber,is critically important to prevent toxicity discharge.Low-and high-pH stresses sometimes occur in the effluent treatment systems due to the use of a large amount of acid and alkaline in the pulping process.Using flat separation method to select high-yield strains from bio-contact oxidation basin,seeing configuration of the strains and doing some physiological experiments,we found that the strains contain two kinds of main bacteria,Zoogloea sp.and Pseudomona sp.We also discovered the best growing time by spectrophotometer.The best growing time is at 0～32h,the logarithmic phase is about at 12～32h,and the stable growth phase is about 32～60h.Furthermore,we concluded that the disposal ability of high-yield strain is better than the ordinary one by doing parallel experiment.Through orthogonal test we also confirmed that the best growing temperature and pH value are 29℃and 7.3 respectively.The COD removal rate is about 93% when the biomembrane is in good condition.

Plastic Flow Modeling of Ti-5 Al-2 Sn-2 Zr-4 Mo-4 Cr Alloy at Elevated Temperatures and High Strain Rates

The true stress-sWain relationships of Ti-5A1-2Sn-2Zr-4Mo-4Cr（TC17） alloy with a wide range of strain rates were investigated by tmiaxial quasi-static and dynamic compression tests, respectively. Quasi- static compression tests were carried out with Instron 8874 test machine, while dynamic compression tests were performed with the split Hopkinson pressure bar （SHPB） which was installed with heating device and synchro- assembly system. The dynamic mechanical behaviors tests of TC17 were carded out from room temperature to 800 ℃ at intervals of 200 ℃ and at high sWain rates （5 500-1 9200 s-l）. The stress-strain curves considering temperature-sWain rate coupling actions were obtained. The Johnson-Cook constitutive model was developed through data fitting of the stress-sWain curves. The material constants in the developed constitutive model can be determined using isothermal and adiabatic stress-strain curves at different strain rates. The Johnson-Cook constitutive model provided satisfied prediction of the plastic flow stress for TC17 alloy.

Mechanical model for yield strength of nanocrystalline materials under high strain rate loading

To understand the high strain rate deformation mechanism and determine the grain size,strain rate and porosity dependent yield strength of nanocrystalline materials,a new mechanical model based on the deformation mechanism of nanocrystalline materials under high strain rate loading was developed.As a first step of the research,the yield behavior of the nanocrystalline materials under high strain rate loading was mainly concerned in the model and uniform deformation was assumed for simplification.Nanocrystalline materials were treated as composites consisting of grain interior phase and grain boundary phase,and grain interior and grain boundary deformation mechanisms under high strain rate loading were analyzed,then Voigt model was applied to coupling grain boundary constitutive relation with mechanical model for grain interior phase to describe the overall yield mechanical behavior of nanocrystalline materials.The predictions by the developed model on the yield strength of nanocrysatlline materials at high strain rates show good agreements with various experimental data.Further discussion was presented for calculation results and relative experimental observations.

FEATURE OF SERRATED YIELDING IN HIGH STRENGTH Al-Zn-Mg-Cu ALLOY

The temperature dependence of critical strain for serrated yielding in high strength A1-Zn-Mg-Cu alloy may be divided into two temperature regions.Their temperature coefficients of critical strain will be negative and positive,respectively.

High Strain Rate Induced Plasticity-increasing of Metallic Materials under Tension

The effect of strain rate on plasticity has been Investigat-ed for three metallic materials with dynamic tension tech-nique. A phenomenon of high strain induced plasticity -increasing was found for tested materials. The elongation of quenched 30CrMnSiNi2A is 14. 5% under 40 m/s loading rate which is more than two times of the 7 % un-der 0. 5 mm/min. This typic high strain rate induced plasticity - Increasing phenomenon is associated with adiabatic heating, strain twinning and suppression of strain - induced - phase transformation.

Using irrigation intervals to optimize water-use efficiency and maize yield in Xinjiang,northwest China

Worldwide, scarce water resources and substantial food demands require efficient water use and high yield.This study investigated whether irrigation frequency can be used to adjust soil moisture to increase grain yield and water use efficiency(WUE) of high-yield maize under conditions of mulching and drip irrigation.A field experiment was conducted using three irrigation intervals in 2016: 6, 9, and 12 days(labeled D6, D9, and D12) and five irrigation intervals in 2017: 3, 6, 9, 12, and 15 days(D3, D6, D9, D12, and D15).In Xinjiang, an optimal irrigation quota is 540 mm for high-yield maize.The D3, D6, D9, D12, and D15 irrigation intervals gave grain yields of 19.7, 19.1–21.0, 18.8–20.0, 18.2–19.2, and 17.2 Mg ha^-1 and a WUE of 2.48, 2.53–2.80, 2.47–2.63, 2.34–2.45, and 2.08 kg m-3, respectively.Treatment D6 led to the highest soil water storage, but evapotranspiration and soil-water evaporation were lower than other treatments.These results show that irrigation interval D6 can help maintain a favorable soil-moisture environment in the upper-60-cm soil layer, reduce soilwater evaporation and evapotranspiration, and produce the highest yield and WUE.In this arid region and in other regions with similar soil and climate conditions, a similar irrigation interval would thus be beneficial for adjusting soil moisture to increase maize yield and WUE under conditions of mulching and drip irrigation.

The Mechanism of Critical Strain of Serrated Yielding in Strain Rate Domain

The mechanism of the critical strain of serrated yielding is studied via tension tests at various strain rates. Betore the critical strain, it is deduced that dislocations are not pinned at high strain rates, and dislocations at low strain rates are pinned but cannot escape. The critical strain depends on the first pinning process at high strain rates and on the first unpinning process at low strain rates. The calculated results based on the two criteria are in good consistency with the experiment.

低能离子注入诱变法选育新硫肽类抗生素166A高产菌株

目的为进一步提高产量,以小单孢菌Micromonospora sp.TMD166-MU1为出发菌株,采用低能离子注入技术,研究不同离子注入参数对菌株存活率、正负突变率的影响,通过突变株抑菌活性变势参数分析,初步探讨N+离子注入对166A生产菌所产生的诱变效果,并结合卡那霉素抗性筛选及牛津杯固体发酵高通量筛选,获得高产菌株。方法利用低能N+离子注入技术对出发菌株TMD166-MU1的孢子进行辐照诱变,以卡那霉素耐受性为选择压力,不同诱变条件处理的菌悬液涂布在含有卡那霉素培养基平板上培养后获得单菌落,并以牛津杯固体发酵高通量筛选方法进行高产菌株初筛,之后对高产菌株进行摇瓶复筛,利用高效液相法检测突变株摇瓶发酵的化学效价。结果通过研究30和60 keV能量下不同注入剂量与小单孢菌正突变率的生物学效应关系,确定了在注入能量为30 keV、注入剂量4×10^(13)ions/cm^(2)、卡那霉素抗性筛选浓度为6 mg/L条件下,可获得最高达36.33%的正突变率。复筛效价是出发菌株1.5倍以上的有4株,其中突变株IK-3的166A产量是菌株TMD166-MU1的1.8倍。结论采用低能N+离子注入诱变方式,再结合抗生素抗性筛选及牛津杯固体发酵高通量筛选的集成方法能简单、高效地获得166A高产突变菌株。

不同应变率下高强钢的拉伸行为及力学性能分析

高强钢因强度高、塑性好、耐腐蚀性优异而得到广泛应用。然而,高强钢具有显著的应变率敏感性。为此,针对2种高强钢(Ultrafort 401和Ferrium S53钢),开展了不同应变率下(10^(-4)~10^(3) s^(-1))的拉伸试验,获得了屈服强度、抗拉强度、硬化指数等性能参量,并深入分析了其随应变率变化的规律。不同应变率下,Ferrium S53钢的拉伸性能始终优于Ultrafort 401钢,但两者却表现出不同的变化趋势。随着应变率的增加,Ultrafort 401钢的屈服强度和抗拉强度均增大,而Ferrium S53钢的屈服强度增大,抗拉强度先减小后增大。结合微观结构表征发现,Ferrium S53钢所具有的较高的屈服强度与其初始晶粒尺寸更小有关,2种高强钢的抗拉强度随应变率增加所表现出的不同变化趋势则与应变硬化响应差异有关。随着应变率的升高,Ultrafort 401钢的韧窝尺寸增大,而Ferrium S53钢的韧窝尺寸先减小后增大,说明2种高强钢的应变硬化水平随着应变率升高而呈现不同的变化趋势。研究结果为高强钢在不同加载条件下的力学性能评估提供了科学依据,对高强钢的工程应用具有一定的指导意义。

离子注入改良维生素C二步发酵混合菌研究(Ⅰ)2-酮基-L-古龙酸高产菌系IPPM-1028的选育

利用离子注入技术选育出２－酮基－Ｌ－古龙酸高产菌系ＩＰＰＭ－１０２８，其转化率较出发菌Ｍ－２９８０提高１８．８％。经传代实验证明，其遗传性状较为稳定，４代平均转化率可达９５．０％。

80 MeV/u C-12离子诱变选育PHB高产菌株

用80MeV/u12C6+离子对一株积累聚β-羟基丁酸酯(PHB)的芽孢杆菌(BacillusP-9)进行诱变选育,最终获得PHB高产株菌G15,其PHB产量达2.93g/L,与出发菌株相比较,PHB积累量提高了1.5倍。研究结果表明,本试验辐照最佳剂量为15Gy。重离子辐照诱变育种效果显著,具有广阔的发展应用前景。

高产γ-氨基丁酸乳酸菌菌株的筛选及诱变育种研究

以乳酸菌作为出发菌株,将其接入豆浆(大豆水=1 8)进行发酵,根据发酵过程中γ-氨基丁酸(GABA)产量,筛选出GABA的高产乳酸菌菌株,然后利用紫外线对高产菌株进行诱变处理,筛选得到稳定高产GABA突变菌株。结果表明,保加利亚乳杆菌L2为高产GABA乳酸菌菌株,GABA产量达到1.066 g.L-1。对L2进行紫外诱变处理的最佳照射时间为50 s,在此照射时间下,获得高产GABA突变菌株L2-4,其在含有1%L-谷氨酸的改良MRS培养基和豆浆中的GABA产量分别为4.235和1.394 g.L-1,比原菌株的GABA产量分别提高了25.63%和30.77%。

重离子诱变选育聚β-羟基丁酸酯高产菌株研究

聚β-羟基丁酸酯(PHB)作为一种新型的生物可降解高分子材料,日益受到人们的广泛重视。利用12C6+离子束对一株聚β-羟基丁酸酯(PHB)产生菌———芽孢杆菌Z-3进行诱变,然后进行筛选,从大量突变株中最终选育出一株PHB高产菌株A11,其PHB产量达到1.404 g/L,是出发菌株的1.33倍。研究结果揭示,重离子诱变育种技术具有良好的诱变效果,是一种有效的微生物诱变育种方法和途径。

红芝LYL263混合培养高产漆酶菌株的筛选

以产漆酶的红芝LYL263菌株为试材,采用不同微生物混合培养的方法,研究了红芝LYL263与苏平平菇、白金金针菇、凤尾菇混合培养的产酶效果和产酶条件,以期能筛选出提高红芝LYL263产漆酶的相容菌株以及与之相适应的产酶条件。结果表明:红芝LYL263与其相容菌株-苏平平菇混合培养后漆酶活性达到1346.4 U·mL^(-1),比红芝LYL263单独培养产酶提高35.7%;红芝LYL263与苏平平菇的接种比例为4:2时,其产酶量最高,最优接种时间是同时接入红芝LYL263和苏平平菇。

直接发酵法生产L-丝氨酸高产菌株的选育

为了解除高浓度L-丝氨酸对3-磷酸甘油酸脱氢酶的反馈抑制,进一步提高L-丝氨酸的产量,以一株能直接利用糖质原料发酵生产L-丝氨酸的谷氨酸棒杆菌SYPS-062-36为出发菌,经硫酸二乙酯逐级诱变处理,在D-丝氨酸抗性梯度平板上挑取正突变株,获得一株遗传性能稳定的高产菌株SYPS-062-33a-18,其可积累L-丝氨酸(11.0±0.25)g/L,较出发菌L-丝氨酸产量(6.65±0.23)g/L提高了65.4%。说明本研究不仅以D-丝氨酸作为抗性平板筛选得到高产L-丝氨酸的突变株,而且为下一步进行反向代谢工程的研究提供了良好的实验材料。

高产γ-氨基丁酸霉菌菌株的筛选及诱变育种

以霉菌作为出发菌株,将其接入大豆-水(3:5,m/V)的发酵培养基中进行发酵,根据发酵过程中γ-氨基丁酸(GABA)产量,筛选出GABA的高产霉菌菌株,然后利用紫外线对高产菌株进行诱变处理,并通过抗性初筛获得长势较好的突变菌株,再分别利用含有质量浓度为1g/100mL L-谷氨酸的PDA综合培养基和大豆水溶液的发酵培养基进行两次筛选,得到稳定高产GABA突变菌株。结果表明,通过对产GABA霉菌菌株的筛选,得到米曲霉3.800为高产GABA霉菌,GABA产量达到0.674g/L。以米曲霉3.800作为原始菌株,对其进行紫外诱变处理,从而获得高产GABA突变菌株,结果表明,利用紫外线对米曲霉3.800进行处理的最佳照射时间为2min。在此照射时间下,通过突变菌株在含有质量浓度为1g/100mL L-谷氨酸的PDA综合培养基和大豆-水溶液的发酵培养基进行两次筛选,最终获得一株稳定的高产GABA突变菌株3.800-4,其在含有质量浓度为1g/100mL谷氨酸的PDA综合培养基中的GABA产量为4.491g/L,比原菌株的GABA产量提高了23.58%;同时其在大豆-水的发酵培养基中的GABA产量为0.874g/L,比原菌株的产量提高了29.67%。

自筛β-葡萄糖苷酶高产菌-N_1制备大豆异黄酮苷元的研究

目的:探索一种用自筛的β-葡萄糖苷酶高产菌-N1制备大豆异黄酮苷元的方法。方法:应用酶学研究常规方法在实验室条件下,用自筛的β-葡萄糖苷酶高产菌-N1获得β-葡萄糖苷酶液,探索制备大豆异黄酮苷元的工艺。结果:实验室制备的大豆异黄酮苷元样品纯度为91.33%,收率为11.44%。大豆异黄酮粗品经处理后,苷的数量减少,大豆苷和黄豆黄苷从28.21%降低到22.93%,染料木苷从8.24%降低到5.67%。苷元的数量明显的增加,大豆苷元从0.04%增加至0.05%,黄豆黄素从的0.003%增加至0.09%,染料木素从0.006%增加至0.07%。结论:研究表明以自筛菌-N1作为酶促反应制备大豆异黄酮苷元的β-葡萄糖苷酶产生菌完全可行。大豆异黄酮粗品经酶液处理后,苷元的数量有明显的增加,尤其是黄豆黄素和染料木素,分别增加了30倍和11.67倍。为进一步研究奠定了基础。

ε-聚赖氨酸高产菌的新型筛选模型

建立了一种简单、快速筛选ε-聚赖氨酸高产菌的新模型。结果表明,在筛选培养基中添加终浓度为0.0015%的中性红,ε-聚赖氨酸产生菌周围形成明显的色素透明圈,且色素透明圈圈径大小和ε-聚赖氨酸含量呈正性相关,从而可以通过色素透明圈径大小简单快速地筛选出ε-聚赖氨酸高产菌株。综合来看,ε-聚赖氨酸高产菌的新型筛选模型简单直观而且经济高效,可大大减小筛选工作量,提高筛选效率,为ε-聚赖氨酸产生菌株和高产菌株的筛选工作提供了方便。

特异性乳糖酶的开发研究进展

乳糖酶是一种重要的生物催化剂,基于其水解和转糖苷功能,能水解乳糖和生产低聚半乳糖。在乳糖酶的实际应用中,受复杂反应体系和反应条件(不适宜的酸碱度、高温和有机溶剂)的影响,乳糖酶的稳定性和酶活性较差,制约了乳糖酶的应用。因此,开发适应工业应用条件的特异性乳糖酶及其高效生产的研究一直是研究者们关注的焦点。本文在介绍耐热乳糖酶、低温乳糖酶、耐盐乳糖酶、酸性乳糖酶和耐溶剂化乳糖酶的研究的基础上,综述特异性乳糖酶的催化机制、高产菌株培育、定向进化以及应用策略等方面的进展,并对工业应用前景进行展望,以期为特异性乳糖酶的深入探索和应用开发提供参考。

2-酮基-L-古龙酸高产菌株的选育

实验采用离子注入技术对"二步发酵法"生产维生素C中的伴生菌-苏云金芽孢杆菌(Bacillusthuringiensis)进行处理,筛选维生素C的前体2 酮基 L 古龙酸的高产伴生菌菌株,以提高发酵生产水平。经过初筛、复筛,获得了使产酸活性提高的突变株,在筛选的646株菌中,有3株菌使收率提高了1-4%。