CO_2浓度倍增对城市油松抗氧化酶活性的影响

利用OTC(开顶箱)法模拟未来CO2浓度,于CO2倍增浓度(700μmol·mol-1)和正常空气CO2浓度(≈350μmol·mol-1)条件下,测定了沈阳市区油松(Pinustabulaeformis)针叶超氧自由基(O2.-)产生速率、过氧化氢(H2O2)含量、超氧化物歧化酶(SOD)与抗坏血酸-谷胱甘肽循环(ASA-GSHcycle)主要酶活性动态变化,探讨高浓度CO2对油松抗氧化酶活性的影响。结果表明:在短期(60d)内CO2浓度倍增使油松超氧自由基(O2.-)产生速率与过氧化氢(H2O2)含量减少,而SOD、抗坏血酸过氧化物酶(APX)、单脱氢抗坏血酸还原酶(MDAR)、脱氢抗坏血酸还原酶(DHAR)、谷胱甘肽还原酶(GR)活性升高;植株抗氧化能力增强,对活性氧清除能力提高;但长期(70d以上)CO2浓度倍增处理则可能使试验结果发生逆转。

CO_2质量浓度对沈阳市银杏生长及光合固碳能力的影响

以生长在沈阳市区内的银杏为试材,使用开顶箱模拟法对倍增CO2质量浓度(700μmol．mol-1)和正常空气CO2质量浓度(≈350μmol．mol-1)条件下,银杏生长参数、叶面积指数、不同天气中净光合速率日变化进行了初步研究,探讨了高质量浓度CO2对单株银杏光合固碳能力的影响。结果表明:CO2质量浓度增高可以显著提高银杏枝条的生长量和银杏的叶面积指数。经高质量浓度CO2处理后,银杏不同天气下光合速率日变化趋势与对照一致,即晴天为双峰曲线,多云天气为单峰曲线,但净光合速率显著高于对照(P<0．001)。由于净光合速率和叶面积指数升高,高质量浓度CO2也显著提高了单株银杏的固碳释氧能力(P<0．01),晴天比对照提高了119．5％,阴天提高了175．4％。

Calorimetric study on two biphenyl liquid crystals

The molar heat capacities of the two biphenyl liquid crystals, 3BmFF and 3BmFFXF3, with a purity of 99.7 mol% have been precisely measured by a fully automated precision adiabatic calorimeter in the temperature range between T = 80 and 350 K. Nematic phase-liquid phase transitions were found between T = 297 K and 300 K with a peak temperature of T-peak = (298.071 +/- 0.089) K for 3BmFF, and between T = 316 and 319 K with a peak temperature of T-peak = (315.543 +/- 0.043) K for 3BmFFXF3. The molar enthalpy (Delta(trs)H(m)) and entropy (Delta(trs)S(m)) corresponding to these phase transitions have been determined by means of the analysis of the heat capacity curves, which are (15.261 +/- 0.023) U mol(-1) and (51.202 +/- 0.076) J K-1 mol(-1) for 3BmFF, (31.624 +/- 0.066) kJ mol(-1) and (100.249 +/- 0.212) J K-1 mol(-1) for 3BmFFXF3, respectively. The real melting points (TI) and the ideal melting points (TO) with no impurities of the two compounds have been obtained from the fractional melting method to be (298.056 +/- 0.018) K and (298.165 +/- 0.038) K for 3BmFF, (315.585 +/- 0.043) K and (315.661 +/- 0.044) K for 3BmFFXF3, respectively. In addition, the transitions of these two biphenyl liquid crystals from nematic phase to liquid phase have further been investigated by differential scanning calorimeter (DSC) technique; the repeatability and reliability for these phase transitions were verified. (C) 2004 Elsevier B.V. All rights reserved.

Low-temperature heat capacities and derived thermodynamic functions of cyclohexane

The low-temperature heat capacities of cyclohexane were measured in the temperature range from 78 to 350 K by means of an automatic adiabatic calorimeter equipped with a new sample container adapted to measure heat capacities of liquids. The sample container was described in detail. The performance of this calorimetric apparatus was evaluated by heat capacity measurements on water. The deviations of experimental heat capacities from the corresponding smoothed values lie within +/-0.3%, while the inaccuracy is within +/-0.4%, compared with the reference data in the whole experimental temperature range. Two kinds of phase transitions were found at 186.065 and 279.684 K corresponding solid-solid and solid-liquid phase transitions, respectively. The entropy and enthalpy of the phase transition, as well as the thermodynamic functions {H-(T)- H-298.15 K} and {S-(T)-S-298.15 K}, were derived from the heat capacity data. The mass fraction purity of cyclohexane sample used in the present calorimetric study was determined to be 99.9965% by fraction melting approach.

长白赤松和红松土壤微生物活性对高浓度CO_2的响应(英文)

研究了2003 年夏季长白赤松和红松土壤微生物活性对高浓度CO2的响应规律。结果表明,长白赤松和红松土壤细菌数量受高浓度CO2影响显著(p < 0.05)减少;与对照箱(350 μmol ·mol-1 CO2)和裸地(350 μmol ·mol-1 CO2)相比,红松土壤淀粉酶和转化酶活性降低,而长白赤松土壤淀粉酶和转化酶活性却表现为增加;同时发现受700 μmol ·mol-1 CO2处理的红松和长白赤松土壤微生物生物量碳均表现为显著降低。DGGE 结果表明:受高浓度CO2 的影响,长白赤松和红松土壤细菌群落结构发生了明显的变化。研究结果表明土壤微生物对高浓度CO2的响应规律与所研究的的树种有关。图2 表2 参29。

长白山次生针阔混交林叶凋落物中有机物分解与碳、氮和磷释放的关系

采用分解袋法,研究了长白山次生针阔混交林内9种树种叶凋落物34个月的分解过程.结果表明:在次生针阔混交林中,不同树种叶凋落物的初始N和P浓度存在很大差异,叶凋落物分解速率(k)与初始N浓度和C/N显著相关.有机物剩余百分率与C剩余百分率呈显著的线性正相关关系,与N和P剩余百分率之间呈显著的二项式回归关系.N和P剩余百分率在初期阶段随有机物分解而增加,达到峰值后逐渐降低.随着有机物剩余百分率的下降,C/N和C/P均呈逐渐降低趋势,各种叶凋落物之间C/N和C/P的差异逐渐减小,分解末期分别趋近于23和350.随有机物剩余百分率的降低,N/P变化不明显,当有机物剩余百分率低于25%时,不同树种叶凋落物之间N/P差异显著下降.有机物剩余百分率可用来预测C、N和P的剩余百分率.

Effect of sodium alginate concentration on membrane strength and permeating property of poly-l-arginine group microcapsule

A novel poly-l-arginine microcapsule was prepared due to its nutritional function and pharmacological efficacy. A high-voltage electrostatic droplet generator was used to make uniform microcapsules. The results show that the membrane strength and permeating property are both remarkably affected with the changes of sodium alginate concentration. With the sodium alginate concentration increasing, gel beads sizes increase from 233 mum to 350 mum, release ratio is also higher at the same time, but the membrane strength decreases.

Investigation of thermodynamic properties of Co2O3 powder

The isobaric molar heat capacities of powder of Co2O3 were determined by an adiabatic calorimeter in the temperature range from 78 to 350 K. No phase transition takes place in this temperature range. The relationship of C-p,C-m with thermodynamic temperature T was established as C-p,C-m = -5 x 10(-6)T(3) + 0.0026T(2) + 0.0325T + 4.2592 (J K-1 mol(-1)), fitting coefficient R-2 = 0.9996. According to this relationship and the relationships between thermodynamic functions, the thermodynamic functions of powder of C2O3 were derived with 298.15 K as reference temperature. Thermal decomposition of Co2O3 powder was studied through thermogravimetry (TG). The possible mechanism of the thermal decomposition reaction was suggested according to the TG result. (C) 2003 Elsevier Science B.V. All rights reserved.

Epoxidation of propylene over Ag-CuCl catalysts using air as the oxidant

Ag-CuCl catalysts were found to be active and selective for the epoxidation of propylene using air as the oxidant. Ag catalyst gives a propylene conversion of 31.6%, with a propylene oxide (PO) selectivity of 0.42% at a reaction temperature of 350 degreesC after 220 min of reaction. Addition of CuCl significantly improves the selectivity to PO, and suppresses the conversion of propylene. The Ag-CuCl (1/0.6) catalyst gives propylene conversion of about 3% and a PO selectivity of about 30% at a reaction temperature of 350 degreesC after 500 min of reaction. The activity of the Ag-CuCl catalyst increases with the reaction time and the selectivity to PO is very stable for this catalyst. It is found that AgCl and CuO phases formed during the catalyst preparation are beneficial to the epoxidation of propylene.

粉煤灰对钝化污泥重金属有效性影响

通过添加不同比例的粉煤灰对城市生活污泥进行钝化,系统的研究了粉煤灰对钝化污泥中金属元素Cd、Pb、Cu、Zn、Ni、Cr、Mn、Fe含量及其有效化的影响。结果表明:粉煤灰对污泥中有效态Cd、Pb、Ni、Cr、Mn、Fe具有钝化作用,其中对Cd和Fe的钝化效果最明显;但对Cu却有促进其向有效态转化的作用;总体上看钝化污泥人工土壤中重金属含量符合国家农用标准,而其中有效态Cd、Pb、Ni、C r的含量均远远低于对植物体造成毒害的临界水平。

红松和长白松针叶暗呼吸对连续4个生长季高浓度CO_2处理的响应

以开顶箱法研究了高浓度CO2对长白山两种针叶树—红松和长白松针叶暗呼吸作用的长期影响.对两个树种连续4个生长季进行700和500μmol·mol-1CO2处理,同时设接受大气CO2浓度(约350μmol·mol-1CO2)的开顶箱为对照,在CO2处理的第2,3和4个生长季分别测定了针叶的暗呼吸速率.结果表明:CO2处理的第2个生长季,高浓度CO2下红松和长白松针叶暗呼吸速率增加,可能与碳氮含量变化有关;CO2处理的第3个生长季,高浓度CO2条件下生长的红松针叶暗呼吸速率增加,长白松针叶的暗呼吸速率下降,两树种呈不同响应主要与植株的生长速率不同有关;CO2处理的第4个生长季,红松和长白松针叶的暗呼吸速率均受高浓度CO2抑制.第3个生长季通过改变测量CO2浓度,发现高浓度CO2对长白松针叶暗呼吸作用的短期效应与长期效应呈现一致性,红松不完全相同.红松和长白松针叶的暗呼吸作用对高浓度CO2的响应与CO2处理时间及植株个体的生长发育阶段有关,暗呼吸速率的变化是CO2直接作用与长期驯化共同作用的结果,不能用短期的测定结果预测针叶暗呼吸对高浓度CO2响应的长期效应.

几种酸性土壤供氮力测定方法的综合评价

模拟旱地条件进行黑麦草盆栽试验,对不同供氮力指标与黑麦草吸氮量相关性进行研究,结果表明,短期好气培养法测定的可矿化氮与吸氮量相关系数为0.820;氯化钾与氯化钙浸提的硝态氮与黑麦草吸氮量的相关系数分别为0.892和0.916,表明硝态氮含量作为土壤供氮能力指标具有一定的稳定性;微生物量氮的测定结果不够稳定且与黑麦草吸氮量相关性不高(r=0.751)。分析表明,氯仿熏蒸-浸提全氮与吸氮量的相关性最好,相关系数可达0.941,是一个较好的供氮力指标。

Modeling the effect of ozone loss on photobleaching of chromophoric dissolved organic matter in the St. Lawrence estuary

Temporal trends in total ozone for the St. Lawrence estuary were estimated from ground-based measurements at the NOAA/CMDL station in Caribou, Maine. Linear regression analysis showed that from 1979 to 1999 total ozone has decreased by about 3.3% per decade on an annual basis and ≤6.2% per decade on a monthly basis relative to unperturbed (pre-CFC) levels. The influence of increased ultraviolet-B (280–320 nm) radiation associated with ozone depletion on water column photochemical processes was evaluated by modeling the photobleaching of chromophoric dissolved organic material (CDOM). Linear regression analysis showed small (<0.5% per decade), but statistically significant upward trends in maximum noontime photobleaching rates. Most notably, positive trends in relative rates for May, June, and July, when maximum absolute rates are expected, were predicted. A global model based on TOMS ozone data revealed increases in photobleaching of ≤3% per decade at high latitudes in the Southern Hemisphere. Radiation amplification factors for increases in photochemically weighted UV (280–400 nm) in response to ozone depletion were estimated at 0.1 and 0.08 for photobleaching of CDOM absorbance at 300 and 350 nm, respectively. Application of the laboratory-based model to conditions that more closely resembled those in situ were variable with both overestimation and underestimation of measured rates. The differences between modeled rates and observed rates under quasi-natural conditions were as large or larger than the predicted increases due to ozone depletion. These comparisons suggest that biological activity and mixing play an important, but as yet ill-defined, role in modifying photochemical processes.