油脂浓度对餐厨废弃物厌氧消化特性的影响

[目的]研究油脂浓度对餐厨废弃物厌氧消化特性的影响。[方法]在中温条件下,采用批式试验研究了不同油脂浓度(15%、20%、25%、30%和35%TS)对餐厨垃圾中温厌氧消化过程中甲烷日产气量、累积产气量及发酵液中p H、氨氮、碳酸氢盐碱度和总有机酸的变化规律。[结果]油脂浓度为25%TS时,餐厨垃圾的累积甲烷产量最高,为606.0 m L/g VS;发酵液中总有机酸和碳酸氢盐碱度(VFA/TIC)均小于0.4,维持了较强的缓冲能力。动力学模型参数表明,油脂浓度越高,餐厨垃圾厌氧消化启动阶段的延滞期越长,油脂浓度为35%TS时的延滞期比35%TS时的延滞期延长了4.4 d。[结论]油脂浓度为25%TS时,获得最大甲烷产量(606 m L/g VS)。     

Kinetics of zinc uptake by mycorrhizal (VAM) and non-mycorrhizal corn (Zea mays L.) roots

Summary The kinetics of Zn absorption were studied in mycorrhizal (Glomus macrocarpum) and non-mycorrhizal roots of corn (Zea mays L.) at pH 6.0 at Zn concentrations of 75 mol to 1.07 mol m^-3. Five concentration-dependent phases of Zn absorption were recognized; phase 0 (1.5–4.0 mmol m^-3) was linear but the other four phases (4.0 mmol to 1.07 mol m^-3) obeyed Michaelis-Menten kinetics. At low concentrations (less than 4 mmol m^-3), sigmoidal kinetics of Zn absorption were observed. The absorption of Zn by mycorrhizal maize was greater at low concentrations but decreased at higher levels. This appeared to be a result of a higher maximal uptake rate in phase 1 and lower K _m values in the subsequent phases. Kinetic models yielding continuous isotherms could not account for the observed multiphasic pattern.Research paper no. 6820 through the Director, Experiment Station, G.B. Pant University of Agriculture and Technology, Pantnagar 263 145, UP, India     

丝素蛋白膜作为葡萄糖氧化酶载体的研究

采用戊二醛共价交联法将葡萄糖氧化酶（GOD）固定在丝素膜上，探讨了酶的固定化方法，研究了固定化酶膜的动力学性质，并与包埋法制备的酶膜进行了比较。共价法可获得高活力的酶膜（534u／cm2），固定化过程中使用甲醇或戊二醛处理对酶活力有轻微影响。固定化GOD最适pH值向中性偏移（pH7．0），最适温度为50℃，热稳定性提高，表观米氏常数比溶液酶降低，酶膜的贮存稳定性良好。     

Chemical kinetics of Japanese cedar,cypress, fir,and spruce and characterization of charcoal

 Thermogravimetric and differential thermal analyses techniques have been applied to investigate the thermal degradation characteristics and chemical kinetics of Japanese cedar, cypress, fir, and spruce. The decomposition of the components could be modeled by an Arrhenius kinetic expression. The kinetic parameters were extracted from the thermogravimetric data using least-squares techniques. The heating rates used for the analyses were 10°, 5°, and 0.33°C/min; and the activation energy and reaction order of the above woods were 7.54, 8.39, 2.87, and 7.88 kJ/mol and 0.71, 0.64, 0.44, and 0.63, respectively. Finally, carbonization was done to produce charcoal from these woods under various operating conditions, and the charcoal was characterized in respect to yield, heating value, electrical conductivity, and X-ray diffraction. The quality of the charcoal from fir was the best among the four types of wood. The charcoal produced is inferior to binchotan (white charcoal) in respect to electrical conductivity and crystalline structure. Received: February 13, 2002 / Accepted: July 12, 2002 Acknowledgment The authors express their gratitude to Professor Yoshida of Applied Chemistry in Tokyo Metropolitan University for performing the TG/DTA in his laboratory and for his valuable suggestions about the analyses.     

黄瓜苗期吸收NO_3~－、K~＋的动力学研究

试验结果表明：黄瓜苗期吸收ＮＯ３－、Ｋ＋的Ｋｍ值分别为０．２５和０．２２ｍｍｏｌ／Ｌ．Ｉｍａｘ分别为７．６７和１２．８６μｍｏｌ／ｇ·ｈ，Ｃｍｉｎ分别为０．０１和０．０２ｍｍｏｌ／Ｌ．说明黄瓜对Ｋ＋的吸收能力大于ＮＯ３－，在黄瓜苗期施用氮肥的同时，要注重钾肥的施用．     

Expansion profiles of wheat doughs fermented by seven commercial baker's yeasts

Commercial baker's yeast consists of Saccharomyces cerevisae, however the strain can vary in each baker's yeast, which might influence the dough fermentation time. The scope of this research was to investigate the dough expansion of wheat doughs fermented by seven commercial baker's yeasts at different yeast concentrations (2.88·10¹¹, 5.76·10¹¹ and 8.64·10¹¹ colony forming units/kg flour) and fermentation temperatures (5 °C, 15 °C, 25 °C and 35 °C). Dough expansion was investigated by monitoring the dough height and it was found to be described well by a first order kinetic model. Doughs fermented with four of the seven yeasts generally had higher kinetic rate constants and hence shorter fermentation times compared to fermentation with the other three yeasts. The shortest fermentation times were found for doughs fermented at 25 °C and the highest yeast concentration, a trend found for all the yeasts tested. The differences in the kinetic rate constants indicate a differentiation in yeast strain among the commercial baker's yeasts emphasising the great importance of the choice of baker's yeast for the dough fermentation time.     

Differential influence of herbicide treatments on activity and kinetic parameters of C4 photosynthetic enzymes from Zea mays

The recommended field dose of rimsulfuron, imazethapyr, alachlor, atrazine or fluometuron differentially reduced shoot fresh and dry weight of 10-day-old maize seedlings as well as leaf protein content during the following 12 days. These reductions seemed consistent during the whole period with fluometuron, atrazine and alachlor but appeared to be nullified by the 5th day of treatment with rimsulfuron and imazethapyr. On the other hand, all herbicides mostly provoked significant inhibitions in specific activities of phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31), malate dehydrogenase (MDH, EC 1.1.1.82), pyruvate phosphate dikinase (PPDK, EC 2.7.9.1) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) in leaves during the first 2 days. Thereafter, the inhibition was recovered in samples treated with rimsulfuron and imazethapyr, leveled off with alachlor but consistently augmented with atrazine and fluometuron. The kinetic characterization showed that rimsulfuron or imazethapyr unchanged V_max of all enzymes in vitro, however, V_max of PEPC, PPDK and Rubisco were decreased in vivo. Nevertheless, atrazine or fluometuron substantially reduced V_max of all enzymes while alachlor showed a reduction in this value of PEPC, MDH and Rubisco. Thus atrazine, fluometuron and, to a lower extent, alachlor reduced concentrations of all enzymes as well as rimsulfuron and imazethapyr for only Rubisco. On the contrary, K_m values of all enzymes were progressively increased by all herbicides indicating that the different herbicides altered the structural integrity of all enzymes. These findings conclude that rimsulfuron or imazethapyr competitively inhibited MDH but revealed mixed inhibition to PEPC, PPDK and Rubisco. Atrazine or fluometuron revealed mixed inhibitions to all enzymes whereas alachlor seemed to be either a competitive inhibitor to PPDK or a mixed inhibitor to PEPC, MDH and Rubisco.     

还原型谷胱苷肽(GSH)作用下土壤磷酸酶动力学特性研究

采用室内培养方法研究还原型谷胱苷肽(GSH)对黑土和棕壤磷酸酶动力学特性的影响。结果显示480mgkg-1(以风干土重计)的GSH处理的黑土磷酸单酯酶、三酯酶和棕壤的二酯酶、三酯酶Vmax值显著大于对照,证明GSH是通过增大酶量实现Vmax值的增大。试验中GSH处理的棕壤磷酸单酯酶及黑土的磷酸二酯酶Km值显著低于对照,说明GSH改变了酶结构,增强了酶与底物的亲和力。     

卵黄提取液防治新城疫—传染性法氏囊病的试验研究

首次应用高免卵黄的三氯甲烷提取液在实验室保护试验成功的基础上对现地588,688只病鸡进行了治疗保护试验,对新城疫(ND)、传染性法氏囊病(IBD)及两者混合感染鸡群的保护率为96.45％,试验结果表明,卵黄提取液的应用为防治ND-IBD病鸡提供了一种可靠的手段。     

Impact of adjuvants on bentazon efficacy on selected broadleaf weeds

Tank-mix adjuvants can increase the efficacy of herbicides. Therefore, the effects of different rates of bentazon alone or tank-mixed with ammonium sulfate, non-ionic (0.25% Induce) or organosilicone (0.1% Kinetic) adjuvants were investigated on cocklebur (Xanthium strumarium), black nightshade (Solanium nigrum), velvetleaf (Abutilon theophrasti), and stranglervine (Morrenia odorata) under greenhouse condition. There were variations in susceptibility of the four weed species to bentazon-adjuvants tank-mixture treatments. Black nightshade control never exceeded 55% with all bentazan treatments rates from 0.84 to 2.24 kg ha⁻¹ with or without the adjuvants. While cocklebur was completely controlled with the application of bentazon at 1.12 kg ha⁻¹, or with bentazon at 0.84 kg ha⁻¹ plus one of the three adjuvants, with insignificant differences between adjuvants. The limited factor of controlling velvetleaf and stranglervine is the bentazon rate. Complete foliar death (98–100%) of velvetleaf and stranglervine was with bentazon at 1.68 kg ha⁻¹ alone or with Induce or Kinetic adjuvant. The results suggested that black nightshade was difficult-to-control weed, while cocklebur was susceptibility to bentazon at lowest rate (0.84 kg ha⁻¹) plus adjuvant. Mixing adjuvant with bentazon generally enhanced common cocklebur and black nightshade control, while addition of adjuvant to bentazon at all rates for controlling stranglervine did not cause any significant difference.