Efficient synthesis of functionalized 2-pyridones by ytterbium chloride catalyzed tandem condensation

An efficient method was developed for the synthesis of arylidene heterobicyclic 3-cyano-2-pyridones via ytterbium chloride catalyzed tandem condensation of aromatic aldehydes,cyclic ketones,and cyanoacetamide.The conditions and scope of the reaction were investigated and a reaction mechanism was proposed.     

Variability of snail growing season at the Chinese Loess Plateau during the last 75 ka

Knowledge of seasonal climate change is one of the key issues facing Quaternary paleoclimatic studies and estimating seasonal climate change is difficult,especially changes such as seasonal length on glacial-interglacial timescales.The stable isotope composition from seasonal land snail shells provides the potential to reveal seasonal climatic features.Two modern land snail species,cold-aridiphilous Pupilla aeoli and thermo-humidiphilous Punctum orphana,were collected from different climatic zones in 18 localities across the Chinese Loess Plateau,spanning 11 degrees of longitude and covering a range of 1000 km2.The duration of the snail growing season(temperature ≥10℃) was shorter(202 ± 6 d) in the eastern Loess Plateau compared with in the western Loess Plateau(162 ±7 d).The δ13C of P.aeoli shells was ?9.1‰ to ?4.7‰ and ?5.0‰ to 0.3‰ for δ18O.For P.orphana,the δ13C ranged from ?9.1‰ to ?1.9‰ and ?8.9‰ to ?2.9‰ for δ18O.Both the δ13C and δ18O differences between the two snail species were reduced from the east to the western Loess Plateau(2.8‰ to 0.2 ± 1.1‰ for δ13C and 4.7‰ to 2.9 ± 1.3‰ for δ18O).These isotopic differences roughly reflect the difference in the growing season lengths between the east and west Loess Plateau indicating that the duration of the snail growing season shortens by 15 d or 19 d if the difference decreases by 1‰ in δ13C or δ18O,respectively.Thus,the difference in δ13C and δ18O between both snail species can be used to reveal the length of the snail growing season in the past.Based on our investigation,the length of the snail growing seasons from the Xifeng region during the last 75 ka was reconstructed.During the mid-Holocene(8-3 ka),the mean isotopic difference from both snail species reached maximum values of 2.6 ± 0.7‰ and 2.1 ± 1.4‰ for δ13C and δ18O,respectively.This was followed by MIS 3 that ranged from 2.5 ± 0.4‰ for δ13C and 1.6 ± 0.8‰ for δ18O.The Last Glacial Maximum changed by only 0.2‰ and 0.4‰ for δ13C and δ18O,respectively.Therefore,we estimate that the duration of the snail growing seasons to be ～200 ± 10 d during the mid-Holocene,190 ± 6 d in MIS 3 and 160 ± 3 d during the last glacial period.     

Degradation of the antibiotic sulfamonomethoxine sodium in aqueous solution by photo-Fenton oxidation

In this study, photo-Fenton oxidation was applied to degradation of sulfamonomethoxine sodium (SMMS) in aqueous solution. The operation parameters of pH, temperature, and concentrations of H2O2, Fe2+ and SMMS were investigated. The optimum conditions for the photo-Fenton process were determined as follows: [SMMS]=4.53 mg/L, pH 4.0, [H2O2]=0.49 mmol/L, [Fe2+]= 19.51 μmol/L and T=25°C. Under these conditions 98.5% of the SMMS degraded. The kinetics were also studied, and degradation of SMMS by the photo-Fenton process could be described by first-order kinetics. The apparent activation energy was calculated as 23.95 kJ/mol. Mineralization of the process was investigated by measuring the chemical oxygen demand (COD), and the COD decreased by 99% after 120 min. This process could be used as a pretreatment method for wastewater containing sulfamonomethoxine sodium.     

Catalytic oxidation of phenol in wastewater-A new application of the amorphous Fe78Si9B13 alloy

The amorphous Fe78Si9B13 alloy was used as a heterogeneous Fenton catalyst in the process of phenol degradation.The influences of main operating parameters such as reaction temperature,catalyst amount,hydrogen peroxide dosage and initial pH of solution on phenol degradation rate were investigated.The maximum mineralization of phenol was achieved at 60°C,6 g/L Fe78Si9B13, 0.31 mol/L hydrogen peroxide,with an initial pH of 2.5.More than 99%of phenol was completely removed under the optimum conditions within 10 min for a solution containing 1000 mg/L of phenol.Batch experiments for solutions containing phenol con- centrations ranging from 50 to 2000 mg/L were investigated under the above conditions and the same excellent degradation rate was obtained.The Fe78Si9B13 showed better catalytic activity than iron powder and Fe 2+ .Addition of n-butannol(hydroxyl radical scavenger)decreased the degradation rate of phenol,which demonstrates that hydroxyl radicals were mainly responsible for the removal of phenol.We demonstrated that phenol may be degraded by hydroxyl radicals decomposed by hydrogen peroxide on the surface of Fe78Si9B13 and illustrated the reaction mechanism for this process.This amorphous alloy exhibited high stability in recycling experiments and showed excellent reuse performance even after continuous operations of 8 cycles.     

Changes in the power spectrum of electrical signals in maize leaf induced by osmotic stress

To quantify the characteristics of the power spectrum of plant electrical signals, we defined the following concepts:spectral edge frequency (SEF), spectral center frequency (SCF), power index (PI) and power spectral entropy (PSE). These parameters were used to examine and quantify changes in the power spectrum of electrical signals in maize leaves under osmotic stress. In the absence of osmotic stress, the SEF of the electrical signal in maize leaves was approx. 0.2 Hz and the SCF was approx. 0.1 Hz. The electrical signal in maize leaves was mainly a slow wave signal with a frequency of 0-0.1 Hz. After 2 h osmotic stress, the SEF and SCF of the electrical signal increased to higher frequencies. The proportion of the fast wave frequency also increased to 0.1-0.2 Hz, resulting in a dramatic increase in PSE. We also found that the changes in PSE and SCF were significantly correlated during osmotic stress. We propose that the changes in the PSE and SCF in maize leaves can be used as a sensitive signal indicating water deficit in leaf cells under osmotic stress. Thus, measurement of SCF or PSE of electrical signals in maize leaves could be used to develop early warning and rapid diagnosis techniques for the water demands of plants.     

泥河湾井儿洼剖面粉砂黏土纹层成分的扫描电镜与能谱分析

利用扫描电镜以及X射线能谱仪,对泥河湾盆地井儿洼剖面的粉砂黏土沉积纹层进行成分分析,结果表明在一个纹层偶中Si和Ca元素的质量含量w存在明显的差异,粉砂纹层中的w(Si)值高,w(Ca)值低;而黏土纹层中的w则正好相反.Si和Ca元素在粉砂纹层和黏土纹层中的交替变化,与碎屑物的组成有关,可能反映了一年中古湖水特征的季节性变化.     

融合多传感器信息的移动机器人自定位方法

提出一种给定环境模型下移动机器人全局自定位算法,通过融合声纳传感器和视觉传感器的异质传感信息把具有多模态、鲁棒性强的Markov方法和单模态、高效准确的EKF方法组合应用并加以改进,来实现准确和快速的全局定位,同时提高位姿跟踪的准确性.Markov方法中位姿空间的低分辨率离散减小了存储需求,声纳感知模型对位姿空间分布进行初始化并提供了全局的位姿假设,视觉感知模型实现了位姿分布更新,而基于视觉特征的EKF方法则提高了定位的精度.实验结果验证了本方法的有效性.     

Fluid/melt inclusions in Cenozoic mantle xenoliths from Linqu,Shandong Province,eastern China: Implications for asthenosphere-lithosphere interactions

Fluid and melt inclusions in mantle xenoliths are thought as direct samples to study mantle liquids. Here we apply Raman mi- crospectroscopy and microthermometry to fluid/melt inclusions in lherzolite xenoliths in Qiaoshan basalts, a Miocene volcano in Linqu, Shandong Province, eastern China. These inclusions include (1) early CO2 fluid inclusions, (2) early carbonate melt inclu-sions, (3) late CO2 fluid inclusions, and (4) late silicate melt inclusions. Among the early CO2 fluid inclusions, most consist of...     

乌鲁木齐河流域气温特征分析

本文根据乌鲁木齐河流域气温观测资料,分析了气温的日、月、年变化的特点。并分析了气温随高程的变化,表明在不同季节和不同高度范围内气温递减率是不同的,提出了计算气温递减率的公式,为冰雪融水和蒸发计算提供了分析依据。