臭氧降解苯乙酮的动力学及机制

研究臭氧化降解苯乙酮效率,利用相对法求算了苯乙酮与臭氧及羟基自由基的反应速率常数。结果表明,臭氧化处理能有效降解苯乙酮,苯乙酮与臭氧的反应速率常数KO3-ACP为0.171 L.mol-1.s-1,与羟基自由基的反应速率常数KOH-ACP为7.07×109 L.mol-1.s-1。不同pH的试验表明,利用测得的两个反应速率常数能很好地预测苯乙酮的降解动力学。气相色谱-质谱联用仪(GC/MS)和离子色谱(IC)的分析结果显示,臭氧化降解苯乙酮的中间产物主要包括苯酚、邻羟基苯乙酮、酒石酸、乙酸和草酸等物质,在此基础上提出了臭氧化苯乙酮的可能降解历程。     

碱式硫酸铝脱硫过程的化学动力学研究

使用500ml球胆通过恒温水域锅进行恒温控制,50ml碱式硫酸铝溶液与200ml纯二氧化硫气体进行吸收反应,通过水域锅加热改变吸收液中分子活性,使分子获得更高的能量,在不同温度条件下测定反应物反应速率,通过Arrhenius反应方程式计算吸收反应速率常数,以及反应活化能。由实验数据表明,经过恒温加热处理后,30℃时吸收液中有效反应物与SO2反应速率常数k1=0.04327,40℃时反应速率常数k2=0.05947,反应活化能Ea=2.56KJ/mol。可以得出吸收液中溶质分子平均活性随温度增高增加,反应物更容易进行反应,从而吸收反应的反应速率加快,碱式硫酸铝溶液吸收二氧化硫效率加强。     

半乳甘露寡糖对育肥猪的应用效果

将48头育肥猪(杜×长×大)随机分为2组,每组3个重复,在同一玉米-豆粕型基础日粮中分别添加0.1%半乳甘露寡糖和50mg/kg金霉素,进行了46d的对比试验.饲养试验结束后从两个处理的每个重复分别选择1头阉公猪屠宰,结果表明(1)生长性能:基础日粮添加0.1%GMOS与添加50mg/kg CTC相比较,平均日增重提高10.2%(P＜0.05),平均日采食量降低25.2%(P＜0.01),料肉比下降13.2%(P＜0.01);(2)屠宰性能:基础日粮添加0.1%的GMOS与添加50mg/kg的CTC相比较,背膘厚下降了15.6%,皮厚下降了11.5%,瘦肉率提高了2.94%,但经统计分析,差异均不显著(P＞0.05);(3)血清生化指标:与添加50mg/kg的CTC相比,基础日粮添加0.1%的GMOS可使育肥猪血清中的血糖水平升高120%(P＜0.05),胆固醇水平下降3.86%(P＞0.05),甘油三脂水平下降42.6%(P＞0.05);(4)猪肉品质:与添加50mg/kg的金霉素相比,基础日粮添加0.1%的GMOS可显著降低肉中吲哚的含量(P＜0.05),对其他肉质指标无显著影响.     

微量热法研究三价砷对土壤的毒性作用

本文应用微量热法研究不同浓度的三价砷对土壤微生物活性的影响.研究发现三价砷能够抑制土壤微生物代谢活性.土壤微生物生长速率常数k,最大热功率Pmax及代谢总热QT都受到不同程度的影响.     

硫磷化合物对轻石脑油裂解结焦影响的中试研究

以轻石脑油为裂解原料,对硫磷化合物的抑制结焦效果进行中式试验研究。采用扫描电子显微镜和能量色散谱仪分析加结焦抑制剂和无结焦抑制剂条件下形成焦层的形貌和成分,采用色谱/质谱联用仪分析裂解尾气成分及含量,并与无抑制剂的裂解试验结果进行对比。结果表明,硫磷化合物的抑制结焦效果为41.2%,炉管出口剥落焦层为较厚的大片状焦,厚度约为100微米,无丝状焦存在。加结焦抑制剂炉管的裂解产物中乙烯收率低于无抑制剂炉管的乙烯收率,丁二烯收率略有提高,但是三烯总收率相差不大。     

运动员稀氧区域训练对肌肉纤维耐久力的影响

目的:研究运动员稀氧区域训练对肌肉纤维耐久力的影响。方法:分析18名运动员在常氧和高原低氧(模拟海拔4500 m递增负荷运动时,低氧通气反应速率、最大摄氧量以及最大耐力持续时间三个肌肉纤维耐久力评估指标的变化情况。结果:高原低氧训练时运动员低氧通气速率和最大耐力持续时间显著高于常氧对应值,高原低氧训练时,运动员最大摄氧量低于常氧对照组。高原低氧训练组,运动员在4个不同功率等级低氧通气速率,均高于常氧对应值,低氧通气速率在50%、75%以及100%最大功率时显著高于常氧对应值,最大摄氧量在各相对功率等级中,无显著性差异。运动员的低氧通气反应速率在高原低氧训练组至75%最大功率阶段降低,在75%至100%最大功率阶段基本保持平稳上升,不同相对强度下低氧训练组运动员最大摄氧量较常氧对应值显著降低。结论:高原运动训练下运动员肌肉纤维耐久力增强,疲劳时间降低,可提高运动员的运动能力。     

半乳甘露寡糖和金霉素对育肥猪生长性能、屠宰性能、血清生化指标和猪肉品质的影响

将48头育肥猪（杜×长×大）随机分为两组，每组三个重复，在同一玉米－豆粕型基础日粮中分别添加0.1%半乳甘露寡糖(GMOS)和50mg/Kg 金霉素(CTC)，进行了46天的对比试验。饲养试验结束后从两个处理的每个重复分别选择一头阉公猪屠宰，结果表明1）生长性能：基础日粮添加0.1% GMOS与添加50mg/Kg CTC相比较，平均日增重提高10.2%（P<0.05），平均日采食量降低25.2%（P<0.01），料肉比下降13.2%（P<0.01）；2）屠宰性能：基础日粮添加 0.1%的GMOS与添加50mg/Kg的CTC相比较，背膘厚下降了15.6%，皮厚下降了11.5%，瘦肉率提高了2.94%，但经统计分析，差异均不显著(P>0.05)；3）血清生化指标：与添加50mg/Kg的CTC相比，基础日粮添加0.1%的GMOS可使育肥猪血清中的血糖水平升高120%（P<0.05），胆固醇水平下降3.86% (P>0.05)，甘油三脂水平下降42.6% (P>0.05)；4）猪肉品质：与添加50mg/Kg的金霉素相比，基础日粮添加0.1%的GMOS可显著降低肉中吲哚的含量（P<0.05），对其它肉质指标无显著影响。     

红茶萃取物及茶黄素对两类酮酰还原酶的抑制作用

利用酶动力学方法测定了50％乙醇红茶萃取物和其主要活性成分茶黄素对存在于动物中的I型脂肪酸合酶的酮酰还原催化中心（KR）和存在于细菌中的II型脂肪酸合酶的酮酰还原酶（FabG）的抑制能力和抑制特征。这两个抑制剂对KR和FabG均有强的可逆抑制和不可逆抑制能力，是KR和FabG的底物NADPH的竞争性抑制剂，并且NADPH可以显著降低它们不可逆失活KR和FabG的速率，表明这两个抑制剂可能作用于两种酮酰还原酶的NADPH结合位点。两个抑制剂对KR和FabG的抑制特征基本一致，表明两种不同进化程度的酮酰还原酶的活性部位很相似。序列同源性分析表明它们有一段同源性很高的序列，可能与活性部位组成有关。因此，通过对FabG的研究能够了解KR活性部位的空间结构。由于抑制能力强和来源丰富，这二个抑制剂具有较高的应用潜力。     

水岩作用下湘西北页岩膨胀抑制性实验研究

在钻进页岩气储层时,水岩相互作用是引起井壁失稳的重要原因。对此以湘西北页岩为研究对象,开展了水岩作用页岩水化膨胀抑制性实验,对比了KCl、SDBS和CTAB 3种钻井液体系对湘西北页岩的膨胀抑制性,分析了其膨胀抑制机理,优选出了其膨胀抑制剂的最佳浓度。研究表明:钻井液体系中KCl、SDBS和CTAB浓度小于1. 5%时,钻井液体系普遍具有良好的膨胀抑制性; KCl和SDBS的最佳浓度分别为1. 0%、1. 5%,CTAB浓度在小于0. 5%时抑制效果较好,且随浓度增加,其膨胀量呈线性增长;最优浓度下,湘西北页岩在KCl、SDBS钻井液体系中的最大膨胀量分别为0. 03 mm和0. 13 mm,其最大膨胀速率为0. 0002 mm/min和0. 00092 mm/min。     

不同施肥处理对稻田系统氮素流失的影响

通过测坑定位试验,研究了3种施肥处理下稻田系统氮素流失特征.试验结果表明,施肥后各个处理的稻田坑面水中NH+4-N浓度逐日递减,无机肥处理,混施肥处理和有机肥处理的NH+4-N浓度在施肥第2天分别降低35.17%、24.78%、14.12%;施用有机肥能有效降低氮素在稻田土层中的淋溶速率,低于无机肥处理和混施肥处理,施...     

Insights into the microbial community structure of anaerobic digestion of municipal solid waste landfill leachate for methane production by adaptive thermophilic granular sludge

BackgroundThe amount of municipal solid waste (MSW) gradually increased along with the rapid development of modern cities. A large amount of landfill leachate are generated with excessive chemical oxygen demand (COD), which create a great deal of pressure on the environment-friendly treatment process. Anaerobic digestion is an ideal technique to solve the above problem.ResultsA thermophilic granular sludge was successfully adapted for anaerobic digestion of MSW leachate (from an aging large-scale landfill) for methane production. The COD degradation efficiency improved by 81.8%, while the methane production rate reached 117.3 mL CH₄/(g VS d), which was 2.34-fold more than the control condition. The bacterial and archaeal communities involved in the process were revealed by 16S rRNA gene high-throughput pyrosequencing. The richness of the bacterial community decreased in the process of thermophilic granular sludge, while the archaeal community structure presented a reverse phenomenon. The bacterial genus, Methanosaeta was the most abundant during the mesophilic process, while Methanobacterium, Methanoculleus, Methanosaeta and Methanosarcina were more evenly distributed. The more balanced community distribution between hydrogenotrophic and acetotrophic methanogens implied a closer interaction between the microbes, which further contributed to higher methane productivity. The detailed relationship between the key functional communities and anaerobic digestion performances were demonstrated via the multivariate canonical correspondence analysis.ConclusionsWith the assistance of adaptive thermophilic granular sludge, microbial community structure was more evenly distributed, while both of COD degradation rate and methane production was improved during anaerobic digestion of MSW landfill leachate.How to cite: Feng S, Hou S, Huang X, et al. Insights into the microbial community structure of anaerobic digestion of municipal solid waste landfill leachate for methane production by adaptive thermophilic granular sludge. Electron J Biotechnol 2019;39. https://doi.org/10.1016/j.ejbt.2019.04.001.     

Effects of volatile fatty acids in biohydrogen effluent on biohythane production from palm oil mill effluent under thermophilic condition

BackgroundBiohydrogen effluent contains a high concentration of volatile fatty acid (VFA) mainly as butyric, acetic, lactic and propionic acids. The presence of various VFAs (mixture VFAs) and their cooperative effects on two-stage biohythane production need to be further studied. The effect of VFA concentrations in biohydrogen effluent of palm oil mill effluent (POME) on methane yield in methane stage of biohythane production was investigated.ResultsThe methane yield obtained in low VFA loading (0.9 and 1.8 g/L) was 15–20% times greater than that of high VFA loading (3.6 and 4.7 g/L). Butyric acid at high concentrations (8 g/L) has the individual significantly negative effect the methane production process (P < 0.05). Lactic, acetic and butyric acid mixed with propionic acid at a concentration higher than 0.5 g/L has an interaction significantly negative effect on the methanogenesis process (P < 0.05). Inhibition condition had a negative effect on both bacteria and archaea with inhibited on Geobacillus sp., Thermoanaerobacterium thermosaccharolyticum, Methanoculleus thermophilus and Methanothermobacter delfuvii resulting in low methane yield.ConclusionPreventing the high concentration of butyric acid, and propionic acid in the hydrogenic effluent could enhance methane production in two-stage anaerobic digestion for biohythane production.     

自然湿地甲烷排放时空变化规律研究（英文）

对三江平原沼泽湿地甲烷排放时空变化规律及其影响因素进行了研究。自然湿地甲烷排放存在着明显的季节性变化，即随着植物生长甲烷排放量不断增加，在8月未达到最大值，而后下降。这一变化特点主要受温度和沼泽静水层深度所控制。春季低温不仅直接降低了甲烷的产生强度，而且也降低了其它好氧微生物的活性，使得沼泽水中存留较多的氧气，这些氧气直接加速了沼泽水中甲烷氧化，同时又提高了沼泽水的氧化还原电位，后者反过来进一步减缓甲烷的产生。三江平原不同植被生长的沼泽甲烷排放通量呈如下特点：毛果苔草>乌拉苔草>小叶章。莎草科植物生长的沼泽中，72-86%的甲烷通过植物排放进入大气，而小叶章生长的沼泽只有28-31%。毛果苔草促进了沼泽水中甲烷的氧化而不是产生，相反小叶章通过释放根系分泌物刺激甲烷产生的能力大于分泌氧气促进甲烷氧化的能力。毛果苔草沼泽水中更高的甲烷浓度是由于深的静水层淹没更多的植物立枯，从而为产甲烷菌提供充足的底物所致。     

Evaluation of triclosan toxic effects on the methanogenic activity

BackgroundTriclosan (TCS) is an antimicrobial agent widely used in health care and consumer products. This compound is present in sludge of wastewater treatment plants (WWTPs), and because of its bactericidal characteristics, it can inhibit the methanogenic activity in anaerobic digestion (AD) technology. The aim of this study was to evaluate the toxic effects of TCS on the methanogenic activity.ResultsBatch anaerobic reactors were used with TCS concentrations of 7.8, 15.7, 23.5, and 31.4 mg/L. These assays consisted in three successive feedings (I, II, and III), wherein the sludge was exposed to each TCS concentration and volatile fatty acid (VFA) substrate. For evaluation of the residual sludge activity during feeding III, only VFA was used. The results showed that the increase in TCS concentrations correlated with the reduction in methane (CH₄) production. In this case, the minimum values were achieved for TCS concentration of 31.4 mg/L with CH₄ levels between 101.9 and 245.3 during feedings I, II, and III. Regarding the effect of TCS on VFA consumption, an inhibitory effect was detected for TCS concentrations of 23.5 and 31.4 mg/L, with concentrations of acetic, butyric, and propionic acids at the end of the assay (37 d) between 153.6 and 206.8, 62.5 and 60.1, and 93.4 and 110 mg/L, respectively. Regarding the removal of TCS during AD, these values were above 47%.ConclusionTCS is an inhibitor of methanogenic activity with a decrease between 63 and 70% during the different feedings. The CH₄ production was not recovered during feeding III, with inhibition percentages of 21–72%.How to cite: Reyes-Contreras C, Leiva AM, Vidal G. Evaluation of triclosan toxic effects on the methanogenic activity. Electron J Biotechnol 2019;39. https://doi.org/10.1016/j.ejbt.2019.03.006.     

有机碳源添加对不同C/N比有机物料氮矿化进程的影响

采用室内恒温控湿好气培养法,研究了掺混不同C/N比有机物料土壤中有机氮的矿化进程,及有机碳源添加对其的影响。培养 30周的结果表明:掺混大豆粉的土壤有机氮的矿化速率最快,在第 30d时达到最大;掺混玉米秸粉土壤有机氮的矿化速率最慢;有机碳源的添加明显抑制了有机氮的矿化进程,但这种抑制作用只是暂时的,最终将以有机氮的矿化分解为发展总趋势。     

The effect of introduction of chicken manure on the biodiversity and performance of an anaerobic digester

BackgroundAmmonium stress is a prime limiting phenomenon that occurs during methane formation from poultry manure. It is caused by elevated ammonium nitrogen concentrations that result from substrate decomposition. The amounts of methane formed depend on the activity of methanogenic microbes.ResultsDuring the research reported in this paper, the response of a mesophilic consortium inhabiting a biogas reactor to rising load of poultry manure was investigated. The taxonomic composition of bacterial population was mostly typical, however syntrophic bacteria were not detected. This absence resulted in limitation of succession of some methanogenic microorganisms, especially obligate hydrogenotrophs. The methanogenic activity of the consortium was totally dependent on the activity of Methanosaeta. Inhibition of methanoganesis was noticed at ammonium nitrogen concentration of 3.68 g/L, total cessation occurred at 5.45 g/L. Significant amounts of acetic acid in the fermentation pulp accompanied the inhibition.ConclusionsThe effectiveness of the consortium was totally dependent on the metabolic activity of the acetoclastic Methanoseata genus and lack of SAOB did not allow hydrogenotrophic methanogens to propagate and lead to cessation of biogas production at an elevated ammonium concentration at which acetoclastic methanogens were inhibited.How to cite: Świątek M, Lewicki A, Szymanowska D, et al. The effect of introduction of chicken manure on the biodiversity and performance of an anaerobic digester. Electron J Biotechnol 2019;37. https://doi.org/10.1016/j.ejbt.2018.11.002.     

十二烷基硫酸钠对合成天然气水合物储气特性的影响

实验研究表明 ,表面活性剂胶束溶液可加快水合物的形成和提高水合物的储气质量。在水合物形成体系实验中 ,添加了阴离子表面活性剂 (十二烷基硫酸钠 ) .结果发现 ,合成天然气 (甲烷、乙烷和丙烷的摩尔分数分别为 92 .0 5 %、4.96%和 2 .99% )在无搅拌 (即静止 )的系统中可快速形成 ,而且极大地提高了水合物的储气能力。对水合物储气而言 ,十二烷基硫酸钠溶液的浓度存在一个最佳值 ,使水合物的储气量达到最大值     

Production rate and diameter analysis of spherical monodisperse microbubbles from two-dimensional,expanding-nozzle flow-focusing microfluidic devices

Flow-focusing microfluidic devices (FFMDs) can produce microbubbles (MBs) with precisely controlled diameters and a narrow size distribution. In this paper, poly-dimethyl-siloxane based, rectangular-nozzle, two-dimensional (2-D) planar, expanding-nozzle FFMDs were characterized using a high speed camera to determine the production rate and diameter of Tween 20 (2% v/v) stabilized MBs. The effect of gas pressure and liquid flow rate on MB production rate and diameter was analyzed in order to develop a relationship between FFMD input parameters and MB production. MB generation was observed to transition through five regimes at a constant gas pressure and increasing liquid flow rate. Each MB generation event (i.e., break-off to break-off) was further separated into two characteristic phases: bubbling and waiting. The duration of the bubbling phase was linearly related to the liquid flow rate, while the duration of the waiting phase was related to both liquid flow rate and gas pressure. The MB production rate was found to be inversely proportional to the sum of the bubbling and waiting times, while the diameter was found to be proportional to the product of the gas pressure and bubbling time.     

筛选青霉素G钾工业盐的优良菌种

青霉素经历了多年的工业发展,以其良好的疗效低廉的价格在抗生素生产领域中占有重要的地位,青霉素G钾工业盐是青霉素的重要部分.供生产罐直接使用的菌种一般为生产种子,生产种子质量的优劣可影响发酵50%的成功率.为了提高青霉素G钾工业盐成品的质量降低成本,应筛选优良菌种.     

Cell-induced flow-focusing instability in gelatin methacrylate microdroplet generation

Photo-crosslinkable gelatin methacrylate (GelMa) microspheres are applicable to deliver cells or drugs in biological or biomedical applications. To fabricate GelMa microdroplets, a flow focusing technique with advantages of size control and rapid production was used in a T-junction microfluidic device. Instability played an important role in promoting microdroplet uniformity. 5 wt. % GelMa prepolymer solution mixed with cells affected cell-induced instability. At low flow rate ratio of GelMa to mineral oil below 0.200, stability was maintained regardless of GelMa concentration (5 and 8 wt. %) and cell presence, which led to uniform microdroplet generation. In contrast, instability at high flow rate ratio above 0.200 was worsened by cell presence and unstable jetting length, resulting in the generation of non-uniform cell-laden microdroplets. Therefore, the effect of cell-induced instability on microdroplet generation was minimized at a low flow rate ratio.