Energy Nonequipartition in a Sheared Granular Mixture

The kinetic granular temperatures of a binary granular mixture in simple shear flow are calculated by means of the Direct Simulation Monte Carlo method. The results show that the temperature ratio is clearly different from unity (as may be expected since the system is out of equilibrium) and strongly depends on the restitution coefficients as well as on the parameters of the mixture. The influence of the temperature differences on the rheological properties is also discussed. The results are compared with the theoretical predictions obtained from the Boltzmann kinetic theory by using a Sonine polynomial expansion. The comparison shows an excellent agreement over the range of parameters investigated.     

Synthesis of Novel Isocytosine Pseudonucleotide Analogues

Abstract

Ethyl dialkylphosphonoacetates were prepared from the corresponding dimethylalkylphosphites via the Arbuzov reaction with ethyl bromoacetate. The phosphonoacetates so produced were converted into enaminoacetates by reaction with DMF dimethylacetal and these were used as bidentate electrophiles for the synthesis of phosphonopyrimidones. Several of these compounds were tested for biological activity but none were found to possess antiviral activity.     

江苏金坛盐矿形成时期盐湖水体成分:来自石盐包裹体的证据

我国白垩纪晚期-古近纪由于燕山运动和喜马拉雅运动,形成了一系列的断陷盆地,金坛盐矿就是该时期始新世中晚期的盐湖沉积.本次研究首次在国内半定量的进行了石盐原生包裹体的分析,发现其中Ca2+缺失而富含SO2-4,原始卤水成分为Na-Mg-K-Ca-C1-SO4体系.     

平滑肌肌球蛋白轻链激酶及ATP结合位点突变体对ATP酶活性的调节作用

目的：探寻MLCK的非激酶活性区域对MLCK活性的影响,进一步阐明MLCK的非激酶活性在调节平滑肌收缩过程中的分子机制。方法：利用编码MLCK全长的pColdI表达载体对其ATP结合位点进行定点突变,获得无激酶活性的MLCK突变体;应用Glycerol—PAGE鉴定肌球蛋白磷酸化水平;应用孔雀绿方法检测重组MLCK对肌球蛋白ATP酶活性的影响。结果：MLCK／△ATP（突变型）失去磷酸化肌球蛋白轻链的激酶活性;重组MLCK（野生型）和MLCK／AATP（突变型）均可以在非钙条件下激活非磷酸化肌球蛋白Mg2＋-ATP酶活性,抑制磷酸化肌球蛋白的Mg2＋．ATP酶活性,而且激活与抑制作用均随着MLCK浓度的增加而增大,但二者对肌球蛋白的ATP酶活性的作用没有显著差异（P〉0．05）。结论：平滑肌肌球蛋白轻链激酶及ATP结合位点突变体具有激活非磷酸化肌球蛋白ATP酶活性的作用。     

Vegetation and soil and plant chemistry on ultramafic rocks in the tropical Far East

The tropical Far East has many outcrops of ultramafic rock including very large areas in Sulawesi (c. 8000 km²) and New Caledonia (c. 5500 km²). The outcrops occur under several different climates, and give rise to a range of soils, the characteristics of which are reviewed. The vegetation on them is very varied. Under the same climate one can find grassland, scrub, and both short and tall rain forests. The variation in species richness on the ultramafics is difficult to explain. The degree of endemism varies too; it is probably less dependent on soil characteristics than on historical factors. The causes of the various unusual types of vegetation on ultramafic outcrops are discussed. It is possible that the somewhat dwarfed forests result from a shortage of one or more major nutrients or from very high soil Mg/Ca quotients or high Ni concentrations. The distinct ‘maquis’ vegetation of New Caledonia, and probably ultramafic scrub elsewhere, has evolved in relation to not only the soil chemical factors just listed but also periodic fire and varying degrees of drought. Fires are certainly more important than was once thought and the adverse soil factors may have a role in delaying recolonisation. The plant chemistry is notable for the presence of species which hyperaccumulate certain elements, notably Ni. This phenomenon is discussed in relation to its ecological importance, which may be protection of the hyperaccumulators against herbivores. The need for a conservation policy for the ultramafic areas is stressed, and mention is made of the restoration work on sites damaged by nickel mining in New Caledonia.     

Accumulative Characteristics of Some Plant Species to Magnesium around a Magnesite Mine Area in Northeast China

The deposition of Mg-rich dust from magnesite calcination can lead to serious soil contamination. As an efficient remediation method, phytoremediation is often used to remove contaminants from the environment. However, no information is available on phytoremediation of Mg-contaminated soils. In this study, we determined the Mg concentrations in above- and belowground parts of six dominant plant species and soils (0–20 cm layer) beneath these plants in a magnesite mining region in Northeast China. Mg was enriched in leaves of all six species. Translocation factors (TF) of all six species were far greater than 1. Enrichment factors (EF) of Kochia scoparia, Cassia nomame, and Hordeum jubatum were 1.1, 1.1, and 1.0, respectively, while those of the other three species were not greater than 0.5. The results suggest that Kochia scoparia, Cassia nomame, and Hordeum jubatum are the potential Mg-accumulators, and could be used for remediation of Mg-contaminated soils.     

An acetylcholinesterase biosensor based on graphene–gold nanocomposite and calcined layered double hydroxide

In this study, a novel acetylcholinesterase-based biosensor was fabricated. Acetylcholinesterase (AChE) was immobilized onto a glassy carbon electrode (GCE) with the aid of Cu–Mg–Al calcined layered double hydroxide (CLDH). CLDH can provide a bigger effective surface area for AChE loading, which could improve the precision and stability of AChE biosensor. However, the poor electroconductibility of CLDHs could lead to the low sensitivity of AChE biosensor. In order to effectively compensate the disadvantages of CLDHs, graphene–gold nanocomposites were used for improving the electron transfer rate. Thus, the graphene–gold nanocomposite (GN-AuNPs) was firstly modified onto the GCE, and then the prepared CLDH-AChE composite was immobilized onto the modified GCE to construct a sensitive AChE biosensor for pesticides detection. Relevant parameters were studied in detail and optimized, including the pH of the acetylthiocholine chloride (ATCl) solution, the amount of AChE immobilized on the biosensor and the inhibition time governing the analytical performance of the biosensor. The biosensor detected chlorpyrifos at concentrations ranging from 0.05 to 150 μg/L. The detection limit for chlorpyrifos was 0.05 μg/L.     

Effect of annealing temperature and dopant concentration on the thermoluminescence sensitivity in LiF:Mg,Cu,Ag material

LiF:Mg,Cu,Ag is a new dosimetry material that is similar to LiF:Mg,Cu,P in terms of dosimetric properties. The effect of the annealing temperature in the range of 200 to 350°C on the thermoluminescence (TL) sensitivity and the glow curve structure of this material at different concentrations of silver (Ag) was investigated. It has been demonstrated that the optimum values of the annealing temperature and the Ag concentration are 240°C and 0.1 mol% for better sensitivity, respectively. The TL intensity decreases at annealing temperatures lower than 240°C or higher than 240°C, reaching a minimum at 300°C and then again increases for various Ag concentrations. It was observed that the glow curve structure altered and the area under the low temperature peak as well as the area under the main dosimetric peak decreased with increasing annealing temperature. The position of the main dosimetric peak moved in the direction of higher temperatures, but at 320 and 350°C annealing temperatures, it shifted to lower temperatures. It was also observed that the TL sensitivity could partially be recovered by a combined annealing procedure.