Dispersive-Solid-Phase Extraction Cleanup Integrated to Dispersive Liquid-Liquid Microextraction Based on Solidification of Floating Organic Droplet for Determination of Organochlorine Pesticides in Vegetables

A simple and rapid method applying acetonitrile extraction, dispersive-solid-phase extraction (d-SPE) cleanup, and dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO) was developed for determination of organochlorine pesticides in vegetables. In order to simplify operation, d-SPE cleanup was integrated to DLLME-SFO concentration procedure, and a protection device for glass tube was applied to achieving high-speed centrifugation. The comparison study between the integrated d-SPE and normal d-SPE showed that the former could shorten the sample preparation time without decrease of cleanup efficiency. Subsequently, the necessity of using a high-centrifugation speed (more than 8603 g) for complete separation of the d-SPE sorbents, water phase, and organic phase was confirmed through turbidity analysis. The recoveries of the proposed method ranged from 77.2 to 112.5%, and the relative standard deviations were less than 15%. The limits of detection were in the range of 0.45 ~ 1.33 μg kg^?1, while the limits of quantitation were from 1.35 to 3.99 μg kg^?1, respectively. Finally, the method was successfully applied to analyze real vegetable samples.     

产壳聚糖酶海洋Paenibacillus chitinolyticus CLT08的鉴定及酶学性质研究

目前用于制备壳寡糖的壳聚糖酶具有酶活性较低、酸稳定性较差等问题.本研究从连云港海州湾泥样中筛选产壳聚糖酶菌株,并对菌株进行鉴定、酸稳定性和酶学性质研究.结果表明,通过平板透明圈初筛和摇瓶发酵复筛,获得酸稳定性较好的壳聚糖酶产生菌株CLT08,随后利用形态学特征、生理生化测定及16S rDNA序列扩增与分析,鉴定菌CLT...     

Bacillus sphaericus 2297蛋白酶基因sph在毕赤酵母中的表达及重组酶酶学性质

将Bacillus sphaericus 2297蛋白酶基因sph进行毕赤酵母密码子优化后,进行全基因合成,并构建了重组酵母菌P. pastoris X33-ppicZalphA-sph,对重组酶进行酶学性质研究。结果表明,重组酶的最适反应温度和最适反应pH为40 ℃和8.0,且其为20~30 ℃中保温10 h仍有80%以上的酶活力、在pH7.0~9.0条件下孵育24 h,仍能保持60%以上的酶活性。K+、Sr2+对酶活有明显激活作用,而Fe3+、Ba2+对酶活有明显抑制作用;重组蛋白酶SPH在极性常数为0.8~3.1的25%的正丁醇、环己烷、二甲苯中孵育6 d后,仍能保留50%以上的酶活性。本研究为B. phaericus 2297和B. phaericus DS11蛋白酶有机溶剂耐受性机制的研究奠定基础。     

Induction of cell apoptosis in 3T3-L1 pre-adipocytes by flavonoids is associated with their antioxidant activity

Obesity is biologically characterized at the cellular level by an increase in the number and size of adipocytes differentiated from fibroblastic pre-adipocytes in adipose tissue. In this study, we focused on the relationship between the influence of flavonoids on cell population growth and their antioxidant activity. The results showed that the inhibition of flavonoids (naringenin, rutin, hesperidin, resveratrol, naringin and quercetin) on 3T3-L1 pre-adipocytes was 28.3, 8.1, 11.1, 33.2, 5.6 and 71.5%, respectively. In oxygen radical absorbance capacity (ORAC) assay, quercetin had the highest ORAC(ROO) value among the six flavonoids tested. Apoptosis assays showed that quercetin increased apoptotic cells in time- and dose-dependent manner. Treatment of cells with quercetin decreased the mitochondrial membrane potential in the courses of time and dose. The cell apoptosis/necrosis assay showed that quercetin increased the number of apoptotic cells, but not necrotic cells. Quercetin treatment of cells caused a significant time- and dose-dependent increase in the caspase-3 activity. Western analysis indicated that treatment of quercetin markedly down-regulated PARP and Bcl-2 proteins, and activated caspase-3, Bax, and Bak proteins. These results indicate that quercetin efficiently inhibits cell population growth and induction of apoptosis in 3T3-L1 pre-adipocytes.     

苏云金芽孢杆菌对印度谷螟幼虫的致死作用

根据8株苏云金芽孢杆菌(Bacillus thuringiensis,简称Bt)的菌悬液对印度谷螟幼虫的生物测定结果,筛选出5株对该幼虫致死作用较好的Bt菌株。提取出5株Bt菌株的杀虫晶体蛋白,再对印度谷螟幼虫进行生物测定,结果表明:0.06 mL/g(饲料)的SC1-B3菌株杀虫晶体蛋白对印度谷螟幼虫的致死率达到100%,同样浓度的Bt33菌株杀虫晶体蛋白对印度谷螟幼虫的致死率超过70%,其余3株Bt的杀虫晶体蛋白致死率较低,致死率小于22.2%,但对印度谷螟幼虫的羽化有明显的抑制作用。     

发酵法制备大豆肽的工艺优化及其抗氧化能力

主要研究了枯草芽孢杆菌1398发酵制备大豆肽的工艺条件。以大豆肽含量和平均肽链长度为指标,通过对蔗糖添加量、水分添加量、接种量、发酵温度、发酵时间的单因素实验和正交实验,确定了发酵法制备大豆肽的最优工艺条件:蔗糖添加量0.5%,水分添加量70%,接种量2.0%,32℃条件下发酵32 h。此条件下测得短肽含量为252.95 mg/g。初步提纯后,粗肽的DPPH.,O2-.和.OH清除能力较市售肽分别提高了119.53%,26.02%,65.56%。实验结果表明,发酵工艺能够显著提高产物的大豆肽含量及抗氧化能力。     

Combination of Sanguisorbigenin and Conventional Antibiotic Therapy for Methicillin-Resistant Staphylococcus aureus: Inhibition of Biofilm Formation and Alteration of Cell Membrane Permeability

Methicillin-resistant Staphylococcus aureus (MRSA) infection is challenging to eradicate because of antibiotic resistance and biofilm formation. Novel antimicrobial agents and alternative therapies are urgently needed. This study aimed to evaluate the synergy of sanguisorbigenin (SGB) isolated from Sanguisorba officinalis L. with six conventional antibiotics to achieve broad-spectrum antibacterial action and prevent the development of resistance. A checkerboard dilution test and time-to-kill curve assay were used to determine the synergistic effect of SGB combined with antibiotics against MRSA. SGB showed significant synergy with antibiotics and reduced the minimum inhibitory concentration of antibiotics by 2–16-fold. Biofilm inhibition assay, quantitative RT-PCR, crystal violet absorption, and transmission electron microscopy were performed to evaluate the synergy mechanism. The results indicated that SGB could inhibit biofilm formation and alter cell membrane permeability in MRSA. In addition, SGB was found to exhibit quite low cytotoxicity and hemolysis. The discovery of the superiority of SGB suggests that SGB may be an antibiotic adjuvant for use in combination therapy and as a plant-derived antibacterial agent targeting biofilms.     

采煤沉陷区土地复垦的几种简易方法

采煤沉陷是严重影响人民生活和生产建设的主要地质灾害之一,为了解决这一问题,土地复垦势在必行。使用粉煤灰、煤矸石、湖泥、河泥进行土地复垦,使可耕土地面积增大,土地功能得以恢复,取得了很好的社会和经济效益。     

壳聚糖-琼胶复合微球的制备及其药物释放性能

采用小分子离子交联法制备了pH值敏感的壳聚糖-琼胶复合微球,对壳聚糖-琼胶复合微球的粒径、形貌、pH值敏感性等进行了表征.以茶碱为模型药物研究了壳聚糖-琼胶复合微球的药物释放性能,结果发现一定量琼胶的引入有助于改善壳聚糖微球的药物缓释性能.     

Crystallization of Li2O · Al2O3· 6SiO2 Glasses Containing Niobium Pentoxide as Nucleating Dopant

Niobium pentoxide (T form, orthorhombic system) was utilized to promote devitrification in Li₂O · Al₂O₃· 6SiO₂ glasses. Two or more mole percentage of this nucleating dopant enhanced crystallization in these glasses. Glasses containing 4.0 and 8.0 mol% T-Nb₂O₅ exhibited a high tendency to form dispersed TT-Nb₂O₅ (monoclinic system) precipitates during the glass quenching process. The crystallization process in glasses containing 2.0 or 4.0 mol% T-Nb₂O₅ occurred as microphase separation, followed by the formation of dispersed TT-Nb₂O₅ crystalline precipitates (760°C), followed by β-quartz solid-solution ( ss ) formation (850° to 900°C) heterogeneously nucleated from the precipitates. β-quartz( ss ) transformed to β-spodumene( ss ), along with a polymorphic transition from the TT-Nb₂O₅ to M-Nb₂O₅ (tetragonal system) crystalline phase.