镧对青菜生物量、植株氮磷钾含量及土壤酶活性的影响

利用盆栽试验,研究了镧对青菜生物量、植株氮磷钾含量及土壤酶活性的影响.结果表明,施用镧显著增加了青菜生物量,与对照相比地上部干重提高了5.49%～19.78%,根干重提高了13.51%～51.35%.在低浓度下,随镧浓度的升高,青菜茎叶和根的氮、磷、钾含量逐渐增加,到一定浓度后,随着镧浓度的继续升高,含量反而逐渐降低.镧施入土壤后对脲酶、酸性磷酸酶、转化酶活性表现出刺激作用并随浓度的升高而增强,而对过氧化氢酶活性有轻微的抑制作用,对脱氢酶活性有强烈的抑制作用.     

聚双(2-吡咯基乙氧基磷腈)的合成、氧化交联和导电性研究

有机 /无机杂化聚磷腈具有优良的加工性能和使用性能 ,可以在许多领域获得应用 [1] .具有光电活性的聚磷腈研究也引起了广泛的关注 [2～ 4 ] . Allcock等 [2 ] 合成了具有离子传导特性的聚磷腈 ,可应用于锂离子电池 .具有非线性光学特性的聚合物也有研究报道 [3 ] . L eung等 [4 ] 合成了具有电致发光基团的聚磷腈 ,部分聚合物具有蓝光发射的特征 .合成化学键合的聚 (N -烷基 )吡咯通用聚合物复合膜材料已经得到了重视[5,6] .本文合成了 2 -吡咯基乙醇 ,将其与反应性无机聚合物聚 (二氯 )磷腈进行高分子取代反应 ,合成了含吡咯侧基的聚磷…     

生物膜脱除方式对受污染源水生物接触氧化修复系统除磷性能的影响

针对生物接触氧化修复工艺存在的生物膜内磷累积导致系统除磷性能恶化的问题,以受污染源水为对象,开展表层生物膜脱除(SBD)和全层生物膜脱除(FBD)两种排泥方式对系统除磷长效性和运行稳定性的影响研究.结果表明,生物接触氧化修复系统启动1周后除磷效率达46.9%,随后系统除磷性能迅速恶化.采用FBD方式后系统除磷效果得以恢复,溶解性磷酸盐(DP)去除率维持在30%以上近1个月,生物膜饱和吸磷量达(318.5±21.5)mgTPm-2填料表面积.相比而言,采用SBD方式处理后系统除磷性能未能得到有效改善,30%以上DP去除率仅维持1周左右,生物膜饱和吸磷量仅为FBD的0.68倍.推测不同脱除方式对生物膜二次成膜过程微生物菌群结构重建和污染物去除性能影响显著,FBD处理后系统二次成膜过程溶解氧扩散不受限制,聚磷菌相对反硝化菌更易定殖、富集.镜检结果表明,FBD处理后填料表面仍附着少量微生物及其分泌物(如胞外多聚物等),与新填料表面光滑特性相比,其较高的孔隙率和较强的生物亲和性有利于微生物快速附着成膜,保证排泥强化除磷后系统氨氮、高锰酸盐指数、总氮去除性能稳定.     

ZSM-5分子筛的酸性质和乙醇脱水成醚的催化作用研究

用原位红外技术、等温吸附、程序升温脱附、X射线光电子能谱研究了HZSM-5和磷改性的ZSM-5分子筛的酸性质和表面性质,并与催化乙醇制乙醚的活性和选择性进行了关联。结果表明,样品的总酸度与乙醚产率和乙醇转化率有关。磷的掺入使酸度增加,酸强度降低,有利于乙醚产率的提高和抑制副产物乙烯及积炭的生成。     

组氨酸激酶HK853酸碱调控机制的NMR研究

双组分信号转导系统是细菌应对外界刺激和调控自身生理活动的重要系统。组氨酸激酶是双组分信号转导系统的重要组成部分,大多数组氨酸激酶具有多功能性,不仅能自身磷酸化并能把磷酸基团传递给应激调节蛋白(Response regulator,RR)使之磷酸化,还能催化RR的去磷酸化。研究发现组氨酸激酶HK853的功能受pH值调控,该文利用选择性同位素标记方法,通过NMR技术研究了参与HK853与RR468相互作用的关键氨基酸位点。发现DHp结构域His260侧链的pKa值与HK853的磷酸酶活性有很好的对应关系,HK853与底物形成复合物后其pKa值降低,使His260侧链更易于去质子化,有助于HK853磷酸酶活性的提高。阐明了HK853行使磷酸酶功能时的酸碱调控机制。     

中空纤维膜固定化甲酸脱氢酶催化CO_2合成甲酸

以紫外光表面接枝改性的聚乙烯(PE)中空纤维膜为载体,采用共价结合的方式固定化甲酸脱氢酶(FDH),考察了CO2通入方式、溶液pH值、缓冲液种类和还原型烟酰胺腺嘌呤二核苷酸(NADH)的浓度对酶催化CO2合成甲酸反应的影响.结果表明,与加压法相比,CO2鼓泡法更有利于甲酸的生成;磷酸盐缓冲液优于Tris-HCl和盐酸三乙醇胺缓冲液;体系pH值对反应的影响较大,固定化FDH的最佳pH值仍为6.0,但pH耐受性增强;随着辅酶NADH浓度的增加,反应初速度加快,收率下降;游离酶和固定化酶的最大酶活分别为0.246和0.138mmol/(L.h);固定化FDH在4℃贮存两周后活性仅下降4%,而游离酶活性下降50%.FDH催化膜重复利用10次后,活性没有明显降低.     

高性能自修复微胶囊预聚物组成的研究

为了指导高性能自修复微胶囊的制备研究,利用偏光显微熔点仪、红外光谱和核磁共振氢谱定量研究了微胶囊预聚物组成随反应条件如反应温度、pH值和甲醛-尿素物质的量比的变化.研究结果表明,升高体系温度和pH值都会显著促进副反应的发生从而降低产物中二羟甲基脲的产率;而提高甲醛-尿素的物质的量比,二羟甲基脲的产率增加,同时三羟甲基脲的产率降低.此外,还研究了升温过程中反应体系的温度变化情况.研究发现:升温速率一定时,反应体系的温度变化均匀,没有温度骤变阶段.     

CTAB透性化酵母细胞生物催化合成(S)-(+)-3-羟基丁酸乙酯

 利用十六烷基三甲基溴化铵(CTAB)透性化啤酒酵母细胞中高活性的脱氢酶,借助于辅助底物乙醇和葡萄糖,对3-羰基丁酸乙酯(EOB)不对称还原合成(S)-(+)-3-羟基丁酸乙酯((S)-(+)-3-EHB)进行了研究. 结果表明,CTAB透性化酵母细胞中的醇脱氢酶和6-磷酸葡萄糖脱氢酶的活性分别比未经处理的酵母细胞高482倍和6.5倍. 在相同条件下,CTAB透性化细胞对EOB的还原比未经处理的酵母细胞快. 细胞浓度对反应有明显影响,当透性化酵母细胞浓度＜90 mg/ml时,(S)-(+)-3-EHB的产率和对映体过量值都较低; 当酵母细胞浓度≥90 mg/ml,在最佳进料速率、最适温度和pH条件下,振摇速度为125 r/min时, (S)-(+)-3-EHB的浓度达到最大值314 mmol/L. 在反应开始的6 h内,(S)-(+)-3-EHB的产率可达94%,对映体过量值≥98%,但24 h后产率和对映体过量值分别降低到85%和91%.     

心肌细胞膜ATP酶活性在线测定及变化规律研究

基于流动注射停流技术和软物质在线采集技术建立了一种快速磷钼染色法测定细胞膜三磷酸酰苷(ATP)酶活性的方法.与传统方法相比,该分析方法速度提高了7倍,而且操作简便,试剂消耗少.将该方法应用于兔心肌细胞膜ATP酶活性变化规律的研究,结果显示酶活性在研究时间内按一定规律递减.为细胞膜及其受体的纯度、活性等相关研究提供了重要信息.     

化学改性对催化裂化催化剂氢转移性能的影响

 研究了用草酸处理裂化催化剂的活性组分USY型分子筛以及在催化剂基质中添加磷改性的氧化铝等方法对裂化催化剂氢转移反应活性的影响. 实验结果表明,酸处理能脱除USY型分子筛孔道中的无定形氧化铝,疏通分子筛孔道,提高分子筛的氢转移反应活性,减少积碳; 对于含稀土的REUSY型分子筛,酸处理首先脱除的是稀土离子,降低了分子筛的裂化反应活性,但提高了氢转移反应活性. 在催化剂基质中添加磷改性的氧化铝能增加基质的弱酸性中心,增加裂化反应的活性中心,提高催化剂的裂化及氢转移反应活性,同时减少催化剂上的积碳.     

A Novel Approach for Phosphorus Recovery and No Wasted Sludge in Enhanced Biological Phosphorus Removal Process with External COD Addition

In enhanced biological phosphorus removal (EBPR) process, phosphorus (P) in wastewater is removed via wasted sludge without actual recovery. A novel approach to realize phosphorus recovery with special external chemical oxygen demand (COD) addition in EBPR process was proposed. During the new operating approach period, it was found that (1) no phosphorus was detected in the effluent; (2) with an external addition of 10 % of influent COD amount, 79 % phosphorus in the wastewater influent was recovered; (3) without wasted sludge, the MLVSS concentration in the system increased from 2,010 to 3,400 mg/L and kept stable after day 11 during 24-day operating period. This demonstrates that the novel approach is feasible to realize phosphorus recovery with no wasted sludge discharge in EBPR process. Furthermore, this approach decouples P removal and sludge age, which may enhance the application of membrane bioreactor for P removal.     

Metabolic Behavior and Enzymatic Aspects of Denitrifying EBPR Sludge in a Continuous-Flow Anaerobic–Anoxic System

The metabolic aspects of enhanced biological phosphorus removal (EBPR) were investigated for the first time in a continuous-flow anaerobic–anoxic plant fed with acetate, propionate, or substrates which are involved in the tricarboxylic acid and/or glyoxylate cycle, i.e., fumarate, malate, or oxaloacetate, as the sole carbon source. Although the polyphosphate-accumulating organisms (PAOs) population remained stable with any carbon source examined, no typical EBPR metabolism was observed during fumarate, malate, or oxaloacetate utilization. Specific enzymatic activities related to EBPR were determined in activated sludge homogenates and directly correlated with the nutrient metabolic rates. The experimental results indicated the direct involvement of alkaline phosphatase, pyrophosphatase, and exopolyphosphatase in the denitrifying EBPR process. Metabolic aspects of glyoxylate cycle enzymes are discussed with regard to the biomass anaerobic and anoxic activity. Process performance was highly influenced by the kind of substrate utilized, indicating that specific metabolic pathways should be followed to favor efficient EBPR.     

Optimisation of poly-beta-hydroxyalkanoate analysis using gas chromatography for enhanced biological phosphorus removal systems

Poly-beta-hydroxyalkanoate (PHA) is a polymer commonly used in carbon and energy storage for many different bacterial cells. Polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs), store PHA anaerobically through metabolism of carbon substrates such as acetate and propionate. Although poly-beta-hydroxybutyrate (PHB) and poly-beta-hydroxyvalerate (PHV) are commonly quantified using a previously developed gas chromatography (GC) method, poly-beta-hydroxy-2-methylvalerate (PH2MV) is seldom quantified despite the fact that it has been shown to be a key PHA fraction produced when PAOs or GAOs metabolise propionate. This paper presents two GC-based methods modified for extraction and quantification of PHB, PHV and PH2MV from enhanced biological phosphorus removal (EBPR) systems. For the extraction of PHB and PHV from acetate fed PAO and GAO cultures, a 3% sulfuric acid concentration and a 2-20 h digestion time is recommended, while a 10% sulfuric acid solution digested for 20h is recommended for PHV and PH2MV analysis from propionate fed EBPR systems.     

ADENYLATE KINASE BOUND TO THE CHROMATOPHORE MEMBRANES OF Rhodobactor spheroides G1C

Transformation of adenylates (AMP, ADP and ATP) by washed chromatophore membranes of Rhodobactor spheroides G1C in the dark and in the light indicated the functions of ATPase (ADP + Pi in equilibrium ATP) and of an adenylate kinase (2ADP in equilibrium AMP + ATP). The activity of adenylate kinase of the chromatophores was not inhibited by AP5A, and persisted even after sonication in the presence of EDTA or CaCl2; the results suggested the presence of an adenylate kinase bound to the chromatophore membrane. In search of the enzyme, the supernatant after sonication of the chromatophores in the presence of EDTA was subjected to a molecular sieve and then to ion-exchange HPLC; a fraction with high specific adenylate kinase activity, containing a very sharp peak at 55 kDa, was isolated. Preliminary characterization indicated that it is different from the well-documented water-soluble 33 kDa adenylate kinase.     

Effects of tetrazolium chloride concentration,O<Subscript>2</Subscript>, and cell age on dehydrogenase activity of <Emphasis Type="Italic">Aspergillus niger</Emphasis>

The effects of triphenyl tetrazolium chloride (TTC) concentration, cell age, and presence of O₂ on the dehydrogenase activity of Aspergillus niger as measured by triphenyl formazan (TF) yield were investigated. The results indicated that increasing TTC concentration initially increased the TF yield and then decreased it. The maximum TF yield was observed at a TTC concentration of 30 g/L for young cells (4 d old) and 20 g/L for old cells (12 d old). Conducting the test under anaerobic conditions increased the TF yield. About 18% of the TF produced was converted back into TTC in the presence of oxygen. The relationship between dehydrogenase activity of A. niger (as measured by TF yield) and cell mass was found to be linear. A kinetic model describing the relationship between reaction rate (micromoles of TF formed per hour) and TTC concentration while accounting for substrate inhibition was developed, and the model constants were calculated. The optimum TTC-test conditions for dehydrogenase activity measurement of A. niger were a TTC concentration of 20 g/L, a pH of 9.0, a temperature of 55°C, an incubation time of 3 h, and anaerobic conditions.     

Waste-activated sludge (WAS) as Cr(III) sorbent biosolid from wastewater effluent

A biological sludge – waste-activated sludge (WAS) – from a dairy filtering station was investigated for the removal of trivalent chromium from aqueous solution. Kinetic results revealed that chromium adsorption was instantaneous. The removal rate increases up to pH 4 for contact times beyond 20 min. The equilibrium state is attained in 30 min in all the considered systems. The reaction orders as well as the diffusion rate constant were determined. Values adsorption isotherms measured at pH 3 generally followed the Langmuir model. The maximum uptake capacity was 25.64 mg/g. Values of thermodynamic parameters show that chromium (III) sorption on WAS is an exothermic process.This study provides an opportunity for the removal of heavy metals such as chromium from aqueous solutions using a low-cost biosolid as adsorbent support.     

Simultaneous saccharification and fermentation of cellulosic biomass to acetic acid

Astrain of Clostridium thermoaceticum (ATCC 49707) was evaluated for its homoacetate potential. This thermophilic anaerobe best produces acetate from glucose at pH 6.0 and 59°C with a yield of 83% of theoretical. Enzyme hydrolysis of two substrates, a-cellulose and a pulp mill sludge, yielded 68% and 70% digestion, respectively. The optimum conditions for the simultaneous saccharification and fermentation (SSF) were substrate dependent: 55°C, pH 6.0 for α-cellulose, and 55°C, pH 5.5 for the pulp mill sludge. In the SSF with α-cellulose, the overall yield of acetate was strongly influenced by the enzyme loading. In a fed-batch operation of SSF with α-cellulose, an overall acetic acid yield of 60 wt% was obtained. Among the factors limiting the yields were incomplete digestion by the enzyme and the end-product inhibition. In the SSF of pulp mill sludge, inhibitors present in the sludge severely limited bacterial action. A large accumulation of glucose developed over the entire process, changing the intended SSF operation into a separate hydrolysis and fermentation operation. Despite a long lag phase of microbial growth, a terminal yield of 85% was obtained with this substrate.     

Improving primary treatment of urban wastewater with lime-induced coagulation

The enhancement of primary treatment efficiency through the coagulation process may yield several advantages, including lower aeration energy in the subsequent biological unit and higher recovery of biogas from sludge digestion. In this work sewage coagulation with lime was studied at pilot plant level, using degritted sewage from the city of Rome. The work aimed at optimising the operating conditions (coagulant dosage or treatment pH, and mixing conditions in the coagulation and flocculation tanks), in order to maximise the efficiency of suspended Chemical Oxygen Demand (COD) removal and to minimise sludge production. Lime dosage optimisation resulted in an optimal treatment pH of 9. Lime addition up to pH 9 may increase COD removal rate in the primary treatment from typical 30-35% of plain sedimentation up to 55-70%. Within the velocity gradients experimented in this work (314-795 s(-1) for the coagulation tank and 13-46 s(-1) for the flocculation tank), mixing conditions did not significantly affect the lime-enhanced process, which seems to be controlled by slow lime dissolution. Sludge produced in the lime-enhanced process settled and compacted easily, inducing an average 36% decrease in sludge volume with respect to plain settling. However excess sludge was produced, which was not accounted for by the amount of suspended solids removed. This is probably due to incomplete dissolution of lime, which may be partially incorporated in the sludge.     

Renewable dehydrogenase-based interfaces for bioelectronic applications

Bioelectronic interfaces that establish electrical communication between redox enzymes and electrodes have potential applications as biosensors, biocatalytic reactors, and biological fuel cells. However, these interfaces contain labile components, including enzymes and cofactors, which have limited lifetimes and must be replaced periodically to allow long-term operation. Current methods to fabricate bioelectronic interfaces do not allow facile replacement of these components, thus limiting the useful lifetime of the interfaces. In this paper we describe a versatile new fabrication approach that binds the enzymes and cofactors using reversible ionic interactions. This approach allows the interface to be removed via a simple pH change and then replaced to fully regenerate the biocatalytic activity. The positively charged polyelectrolyte poly(ethylenimine) was used to ionically bond a dehydrogenase enzyme and its cofactor to a gold electrode that was functionalized with 3-mercaptopropionic acid and the electron mediator toluidine blue O. By reducing the pH, the surface-bound 3-mercaptopropionic acid was protonated, disrupting the ionic bonds and releasing the enzyme-modified polyelectrolyte. After neutralization, fresh enzyme and cofactor were bound, regenerating the bioelectronic interface. Cyclic voltammetry, chronoamperometry, constant potential amperometry, electrochemical impedance spectroscopy, and Fourier transform infrared spectroscopy analyses were used to characterize the bioelectronic interfaces. For the two enzymes tested (secondary alcohol dehydrogenase and sorbitol dehydrogenase) and their respective cofactors (beta-nicotinamide adenine dinucleotide phosphate and beta-nicotinamide adenine dinucleotide), the reconstituted interface exhibited a surface coverage, an electron-transfer coefficient, and a turnover rate similar to those of the original interface.     

Polyhydroxyalkanoate granules quantification in mixed microbial cultures using image analysis: Sudan Black B versus Nile Blue A staining

Polyhydroxyalkanoates (PHA) can be produced and intracellularly accumulated as inclusions by mixed microbial cultures (MMC) for bioplastic production and in enhanced biological phosphorus removal (EBPR) systems. Classical methods for PHA quantification use a digestion step prior to chromatography analysis, rendering them labor intensive and time-consuming. The present work investigates the use of two quantitative image analysis (QIA) procedures specifically developed for PHA inclusions identification and quantification. MMC obtained from an EBPR system were visualized by bright-field and fluorescence microscopy for PHA inclusions detection, upon Sudan Black B (SBB) and Nile Blue A (NBA) staining, respectively. The captured color images were processed by QIA techniques and the image analysis data were further treated using multivariate statistical analysis. Partial least squares (PLS) regression coefficients of 0.90 and 0.86 were obtained between QIA parameters and PHA concentrations using SBB and NBA, respectively. It was found that both staining procedures might be seen as alternative methodologies to classical PHA determination.