响应面法分析优化牛粪厌氧发酵工艺参数

选取总固体浓度(TS)、碳氮比(C/N)和发酵时间(T)等3个发酵工艺参数,以沼气产率、甲烷含量和COD去除率作为发酵过程响应指标,运用响应面法(RSM)优化牛粪厌氧发酵工艺条件。结果表明,根据实验数据建立的3个二次多项式数学模型都具有高度耦合性(0.01),并且回归系数(R2)均大于0.9,说明预测值与实验值之间具有很好的拟合度。根据二次多项式方程运用响应面法单独优化沼气产率、甲烷含量和COD去除率的最优条件分别为TS=6.18%,C/N=25.51,T=34.12 d;TS=6.97%,C/N=25.81,T=36.45 d;TS=4.51%,C/N=24.86,T=36.08 d。结果发现,提高沼气产率和甲烷含量与提高COD去除率的最优TS和C/N值是相反的,进一步采用Design-Expert软件寻找出三者共同的优化条件,结果为TS=6.49%,C/N=25.36和T=35.37 d。该条件下沼气产率为230.62 mL/g VS,甲烷含量为70.50%以及COD去除率为57.51%。     

火山石生物滤床对微囊藻毒素的去除

微囊藻水华爆发导致大量微囊藻毒素释放至地表水环境中,严重威胁着饮用水供水安全.通过不同条件火山石自然曝气生物滤床(活性挂膜、灭活挂膜、未挂膜和无填料滤床)对不同形态、构型(MC-LR、MC-RR)的微囊藻毒素的去除实验,探讨其去除效率、途径和机理.结果表明,火山石自然曝气生物滤床对微囊藻毒素的去除是微生物降解和基质吸附共同作用的结果.胞外毒素和胞内毒素的总去除率分别为58％和91％.其中,胞外毒素主要通过微生物降解作用途径去除,占胞外毒素总去除率的(41±4.2)％,胞内毒素则主要通过基质吸附途径去除,占胞内毒素总去除率的(64±5.1)％.生物膜吸附、光降解等其他途径无明显作用.另外,不同构型的微囊藻毒素在火山石自然曝气生物滤床中均能有效去除,MC-LR和MC-RR的去除率分别为68％和54％.     

微波联合酸预处理对厨余垃圾酶水解糖化的影响

酶水解糖化是厨余垃圾制造燃料乙醇的关键步骤,对厨余垃圾进行预处理以促进糖化过程,具有重要意义.以学生食堂厨余垃圾为原料,以常规、微波为加热手段,比较不同预处理方式对厨余垃圾酶水解的影响.结果表明,微波加热结合酸性溶剂的预处理方式最有利于厨余垃圾酶水解糖化.考察微波联合酸预处理的影响因素,得到最佳的预处理条件为:溶剂为H2SO4、溶剂浓度3％、微波功率80 W,预处理时间40 min,固液比1∶8,该条件预处理后,与未经预处理的厨余垃圾酶水解糖产量相比,提高46.1％.     

Interaction of diuron to human serum albumin: Insights from spectroscopic and molecular docking studies

This investigation was undertaken to determine the interaction of diuron with human serum albumin (HSA) was studied by monitoring the spectral behavior of diuron-HSA system. The fluorescence of HSA at 340 nm excited at 230 nm was obviously quenched by diuron due to dynamic collision and the quenching constant was of the order of 10⁴ L mol^?1 at 310 K. However, no fluorescence quenching was observed when excited at 280 nm. Thermodynamic investigations revealed that the combination between diuron and HSA was entropy driven by predominantly hydrophobic interactions. The binding of diuron induced the drastic reduction in α-helix conformation and the significant enhancement in β-turn conformation of HSA. In addition, both sites marker competition study and molecular modeling simulation evidenced the binding of diuron to HSA primarily took place in subdomain IIIA (Sudlow's site II).     

土壤外源Sb(Ⅲ)的老化对其形态和跳虫(Folsomia candida)毒性的影响

老化是影响土壤重金属生物可利用性和毒性的重要因素。为了解老化对土壤Sb形态和毒性的影响,结合化学分析和生物测试,以模式生物跳虫(Folsomia candida)为受试生物,研究了北京潮土中外源Sb(Ⅲ)分别老化7 d、60 d后价态、水溶态和急性/慢性毒性的变化。结果表明,老化仅7 d后,土壤较低浓度的Sb主要以Sb(Ⅴ)存在,而浓度较高(1 600、2 400、4 800 mg·kg-1)时Sb(Ⅴ)分别仅占47.4%、27.5%和2.2%,但老化长达60 d后,浓度最高(4 800 mg·kg-1)的土壤中Sb(Ⅴ)的比重上升到38.1%,其他浓度处理的土壤中,均以Sb(Ⅴ)为主。随着老化时间的延长,土壤中水溶态Sb含量占总Sb的比例显著降低。与土壤老化过程中毒性较大的Sb(Ⅲ)向毒性较小的Sb(Ⅴ)转化与水溶态Sb含量下降相一致,Sb对跳虫的毒性随老化时间的延长明显减弱:7 d老化后土壤Sb对跳虫急性存活的半数致死浓度(LC50)为2 105 mg·kg-1,对跳虫慢性存活的LC50为683 mg·kg-1,对跳虫繁殖的半数效应浓度(EC50)为307 mg·kg-1;老化60 d后土壤Sb对跳虫急性存活、慢性存活的LC50均大于设置的最高浓度,对跳虫繁殖的EC50为1 419 mg·kg-1。因此,对于Sb这种变价金属而言,当进行土壤Sb生态毒性评价时,为避免高估其生态风险,考虑老化作用显得尤为重要。     

Removal of <Emphasis Type="Italic">Anabaena spiroides</Emphasis> by potassium permanganate pre-oxidation: effect on photosynthetic capacity and molecular weight distribution

Bench scale tests were conducted to investigate the effect of potassium permanganate pre-oxidation on the photosynthetic activity and molecular weight distribution of Anabaena spiroides. Different concentrations of potassium permanganate were added into the suspension of Anabaena spiroides, one of the dominant algae in water bloom, and after pre-oxidation of permanganate for 1 h, the results show that the removal rate significantly increases by 33.99~36.35% compared to direct coagulation. Then, the algal characteristics, including photosynthetic ability, the changes in extracellular organic matter three-dimensional fluorescence, and the distribution of molecular weight were conducted and the results show that along with increasing concentration of potassium permanganate, the photosynthetic ability of algae decreases, more extracellular organic matter is secreted, and large molecular weight matter (humic-like and fulvic-like substances) are generated. Therefore, this study demonstrates that potassium permanganate could be used in addressing the algae-rich water.     

2A97铝合金硫酸阳极氧化搅拌摩擦焊对接结构件在热带岛礁海洋大气环境暴露初期的失效行为

研究了铝合金搅拌摩擦焊对接结构硫酸阳极化试样在热带岛礁海洋大气环境暴露初期的失效行为,并对失效机理进行了阐述。通过对在热带岛礁大气环境中暴露初期的试样进行外观观察、光学显微观察、扫描电镜(SEM)观察和能谱分析(EDS)、以及电化学阻抗测试(EIS),阐述了相关变化过程。试样暴露1年后,在0.01Hz处的阻抗模值由初始的2.08×10~6Ω变为5.51×10~5Ω。试样在热带岛礁大气环境暴露1年后热影响区的阳极氧化膜有轻微褪化,电化学阻抗随暴露时间的增加而略有下降。     

中空分子印迹微球的制备及其选择性吸附阿莫西林性能研究

研究以UiO-66为稳定粒子,阿莫西林(AMOX)为模板分子通过皮克林乳液法制备分子印迹中空微球(MIHM),并用于分离富集溶液中的阿莫西林.通过SEM、FT-IR和XRD等方法和静态吸附实验对MIHM的理化性质和吸附性能进行研究.结果表明,UiO-66纳米粒子能够稳定皮克林乳液,粒子分布于中空MIHM胶囊表面,胶囊粒径约为20—60μm.吸附实验结果表明,MIHM对AMOX有较大的吸附容量,吸附容量在318 K,100 mg·L~(-1)的AMOX溶液中达到0.1376 mmol·g~(-1),在选择性吸附实验中对AMOX具有选择性识别性能.经过3次循环回用后材料吸附容量降低12.71%,有良好的再生性.