2，4-二硝基甲苯加氢反应历程及操作条件对反应速率的影响

研究2,4-二硝基甲苯(2,4-DNT)在Ni/硅藻土催化剂上的加氢反应历程和操作条件对反应速率的影响.通过GC-MS分析,提出2,4-DNT加氢合成2,4-二氨基甲苯(2,4-TDA)的反应历程.用初速率分析法考察操作条件对反应速率的影响,分析结果表明:在最佳实验条件下,当搅拌速率达1 500 r/min时,反应进入本征区;反应速率随催化剂用量的增加而线性增加;反应速率随压力和温度的升高而加快;温度与催化剂用量是影响2,4-DNT加氢反应速率的关键因素.     

Degradation of 2,4-dichlorophenol catalyzed by the immobilized laccase with the carrier of Fe3O4@MSS–NH2

With the Fe₃O₄@MSS (magnetic mesoporous silica spheres)–NH₂ as the carrier and the glutaraldehyde as crosslinking agent, the immobilized laccase has been prepared and characterized by XRD, IR, SEM and BET etc. Under the optimal conditions, the removal efficiency of 2,4-DCP reached 88 % and the removal efficiency still remained 61.5 % after five cycles of operations. In virtue of GC–MS analysis, 2,5-dimethoxyl-1,4-quinone, 2-chlorine-1,4-dimethoxyl benzene, 3,3′-dichlorine-4,4′-dimethoxyl biphenyl, maleic acid phenol ester, and three kinds of maleic acid, alcohol ester, and para-hydroxyl phenol ester compounds have been identified as intermediate and final degradation products of 2,4-DCP, respectively. Besides, the degradation products of 2,4-DCP have been confirmed by performing the ¹H-NMR and ¹³C-NMR experiments, further demonstrating the degradation mechanism of 2,4-DCP by the immobilized laccase.     

Effect of irrigation with saline water on soil water-salt dynamics and maize yield in Arid Northwest China

An experiment was conducted in non-weighing lysimeters to study the effect of irrigation with saline water on water movement and salt accumulation and maize yield. The experiment was carried out in northwest China,both sufficient and insufficient irrigation were applied in the first year,and only sufficient treatments in the second year. Irrigation with solute concentration of 9 g·L-1 and 6 g·L-1 led to salt accumulation about 6-8 dS·m-1 in certain depths,even downwards to 160 cm received about 4 dS·m-1 for 9 g·L-1 and 2 dS·m-1 for 6 g·L-1,which was two times more than initial. Salt-affected water extracted from soil behaved as low evapotranspiration under sufficient irrigation,and more water was left in the soil. Yield of spring maize was not affected when saturated soil paste electrical conductivity did not exceeded 1.2 dS·m-1.     

2,4-DNT在鲤鱼肝脏、肠内生物转化的对比研究

通过体外实验,探讨了2,4-二硝基甲苯(2,4-DNT)在鲤鱼肝脏、肠内的生物转化规律,以及2,4-DNT的浓度对生物转化的影响.采用磷酸盐缓冲溶液(pH值为7.4),在通氮气、厌氧条件下,以鲤鱼肝S-9组分和肠内容物为材料研究了2,4-DNT的生物转化.结果表明:鲤鱼肝S-9组分和肠道微生物对2,4-DNT具有代谢作用,在2,4-DNT的生物转化过程中,肝脏起了主要作用,但肠道微生物的作用也不容忽视.     

Room-temperature NH3 sensors with high sensitivity and short response/recovery times

Micro-sensors are fabricated by co-electrospin- ning In203 and SnO2 nanofibers on the substrates of SiO2/Si with interdigitated Pt signal electrodes. The total sensor area is 1.36 mmx 0.55 mm and the active area is only 0.63 mmx 0.55 ram. Excellent NH3 sensing properties are obtained based on the sensors at room temperature. The sensitivity is at most 28 when the sensors are exposed to NH3 of 10 ppm. The response time is 8 s or so and the recovery time is nearly 2 s. Not only fine selectivity, but also long- time stability is obtained. The results not only demonstrate the obtained micro-sensors are very promising devices for NH3 detection, but also show a possible route for large-scale NH3 sensor fabrication at the industrial level.     

Using quantile regression to analyze the stressor–response relationships between nutrient levels and algal biomass in three shallow lakes of the Lake Taihu Basin,China

Understanding the stressor–response relationship between nutrient levels and algal biomass is a prerequisite for the management of eutrophication in lakes. In this study, a quantile regression(QR) approach was used to interpret the stressor–response relationships between nutrient(e.g., phosphorus, nitrogen) concentrations and algal biomass as measured by chlorophyll-a(Chl-a) levels. QR results indicated that Lake Dianshan and Lake Changdang,which are both heavily eutrophicated, were P-limited only.In contrast, Lake Kuilei, which has significantly lower nutrient levels and algal biomass than the other two lakes,was P- and N-limited. Moreover, in Lake Kuilei, N and P levels had significant interaction effects on the algal biomass at the upper quantiles(s [ 0.68). The degree to which the lakes were P-limited increased with rises in the mean total P concentration in the lakes. QR has many advantages over ordinary least squares regression for discriminating limiting factors and, in particular, allows us to estimate changes near the upper extremes of distributions associated with limiting factors. QR is adapted to more specialized risk management problems, such as early warnings of the risk of algal blooms.The probable value-at-risk of harmful algal blooms for Lake Kuilei, Lake Dianshan and Lake Changdang is s = 0.76(Chl-a = 9 mg/m3), s = 0.87(Chl-a = 24 mg/m3) and s = 0.72(Chl-a = 35 mg/m3), respectively. Given the results of the stressor–response relationship analysis, we conclude that reductions in P input represent the most feasible and least costly approach for managing eutrophication in the shallow lakes of the Lake Taihu Basin. To control the magnitude and duration of algal blooms in shallow lakes,reductions in P and N inputs are required. The 95 % CI bounds of slopes indicated that the interactions of nonnutrient factors with nutrients had strong impacts on the algal biomass in lightly eutrophicated Lake Kuilei. It is suggested that, in addition to reductions in nutrient loads,several ecological measures, such as an increase in the biomass of submerged macrophytes and the reduction of hydraulic retention time by flushing, could represent important components of an integrated approach to eutrophication management in the Lake Taihu Basin.     

An ultra-sensitive non-enzymatic hydrogen peroxide sensor based on SiO2-APTES supported Au nanoparticles modified glassy carbon electrode

A novel electrochemical sensor based on (3-aminopropyl)triethoxysilane (APTES) functionalized SiO₂ supported Au nanoparticles and Nafion (Nf) as the protective membrane was fabricated for the electrochemical determination of H₂O₂ in contact lens-cleaning solution. The modification steps of glassy carbon working electrode (GCE) were evaluated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The amperometric results showed that Nf/[email protected]₂-APTES/GCE sensor can be used to determine H₂O₂ in contact lens solutions with the linear ranges of 14–180 μM and 0.18–7.15 mM, excellent sensitivities of 2514.6 and 894.2 μA mM cm^?2, and a low limit of detection (LOD) of 4.25 μM depending upon signal-to-noise ratio of 3. Nf/[email protected]₂-APTES/GCE exhibited excellent repeatability with relative standard deviation (RDS) of 2.66% and acceptable reproducibility with RSD of 3.35%. The sensor displayed reasonable selectivity in the presence of uric acid, dopamine, ascorbic acid, glucose, mannose, glycine, fructose, histidine, and arginine with RSD less than 2.5%. The fabricated Nf/[email protected]₂-APTES/GCE sensor has been successfully applied to detect H₂O₂ in contact lens cleaning solutions.     

Excellent ethanol sensor based on multiwalled carbon nanotube-doped ZnO

Multiwalled carbon nanotubes(MWNTs)were synthesized through CVD method,and the gas sensitive materials MWNTs/ZnO were obtained by mixing MWNTs and ZnO.The gas sensing properties of the as-prepared materials were investigated.The results show that the gas sensing properties of ZnO sensor are significantly improved by doping MWNTs.The sensitivity,response time and recovery time to 50 ppm ethanol at 260°C are 46,4 and 20 s,respectively.We also examined the selectivity of 0.1 wt%MWNTs-doped ZnO sensors to different gases.The results show that the sensor possesses an excellent selectivity to ethanol.     

Export and remineralization of POM in the Southern Ocean and the South China Sea estimated from 210Po/210Pb disequilibria

Disequilibria between ^210Po and ^210Pb in the upper water and their potential applications as a proxy of particle export and remineralization were examined in the Southern Ocean （station IV3） and the South China Sea （NS44）. ^210po was deficit in surface waters but excessive relative to ^210Pb in subsurface waters. Good positive correlation between ^210Po and particulate organic carbon （POC） indicated deficits and excess of ^210Po resulted from particulate organic matter （POM） export and remJneralization respectively, which was also supported by the decreased δ^13C and increased δ^15N downwards as a result of particle remineralization. On the basis of ^210Po/^210Pb box-model, POC export flux out of the surface waters were 1.2 mmol C. m^-2. d^-1 and 2.3 mmol C. m^-2. d^-1 for station NS44 and IV3, respectively. In the subsurface waters, remineralization fluxes of ^210Po were 0.062 Bq. m^-2.d^-1 and 0.566 Bq.m^-2.d^-1 for station NS44 and IV3 along with the recycle efficiency of 52±26% and 119±52%, respectively. Remineralized fluxes of POM derived from ^210Po and exported POC were 0.6 mmol C.m^-2.d^-1 and 2.7 mmol C. m^-2. d^-1 for NS44 and IV3. This study suggested that ^210Po was a powerful tracer of particle export and remineralization.     

分子印迹电化学发光传感器检测毒死蜱

石墨相氮化碳纳米薄片（g-C₃N₄NSs）具有优良的电化学发光（ECL）性能和良好的成膜特性.以g-C₃N₄NSs作为ECL材料,利用其良好的成膜性能将其固定在玻碳电极（GCE）上,再以毒死蜱（CPF）作模板分子,甲基丙烯酸（MAA）作功能单体,通过分子自组装制备分子印迹聚合物（MIP）.将该聚合物引入g-C₃N₄NSs修饰电极,构建了一个MIP-ECL传感器.除去模板分子的传感器能够选择性识别CPF,利用CPF对g-C₃N₄NSs ECL信号的淬灭作用实现了CPF的高灵敏、高选择性检测.传感器对CPF的线性响应范围是1.0×10^-8~1.0×10^-4mol·L^-1,检出限（LOD）是5.0 nmol·L^-1,用于蔬菜中CPF残留量检测,结果令人满意.     

The effect of DIO additive on performance improvement of polymer solar cells

A series of polymer solar cells （PSCs） based on poly （diketopyrrolopyrrole-terthiophene） （PDPP3T） and [6,6]-phenyl-C71-butyric acid methyl ester （PC71BM） as active layer were fabricated to investigate the effect of 1,8- diiodooctane （DIO） on the performance of PSCs. The power conversion efficiency （PCE） of PSCs was increased from 3.77 % to 4.37 % for the cells with DIO additive. The underlying reason may be attributed to that DIO additive could make PC71BM more dispersive in the active layer, forming a better bicontinuous interpenetrating network for excition dissociation and charge carrier transport. There- fore, the short circuit current density （Jsc） and fill factor （FF） was increased from 8.25 to 9.18 mA/cm2 and from 67.2 % to 70.0 % for the PSCs with DIO additive compared with PSCs without DIO additive.     

An explanation to the high efficiency ofm-THPC (temporfin) used in photodynamic therapy

Meso-tetrahydroxylphenyl chlorin (m-THPC) is one of the most efficient prospective sensitizers used in photodynamic therapy (PDT). ESR spectroscopy, fluorescence quenching experiments and cyclic voltammogram measurement were used to study its redox properties. The results showed that the ability of m-THPC generating superoxide radical anions was very strong, and the rate constant of m-THPC fluorescence quenching by oxygen k_q (O₂)=1.46×10¹⁰ mol^-1·s^-1. The values of fluorescence quen- ching rate constant of m-THPC by some other electron acceptors, such as methyl viologen (MV²⁺) and anthraquinone (An), were also measured. And they were k_q (MV²⁺)=5.51×10⁹ mol^-1·s^-1, k_q (An)=7.81×10⁹ mol^-1·s^-1. The oxidation potential of m-THPC was examined to be +0.62 V (vs. NHE) in acetonitrile. All these suggested that m-THPC should be a much stronger electron donor than photofrin, the currently used in clinical photodrug, and may react easily through electron transfer with biological matter to yield various radicals. So it seemed reasonable that the type Ⅰ reaction may play an important role in the high activity of m-THPC-PDT.     

The contribution of root respiration to soil CO2 efflux in Puccinellia tenuiflora dominated community in a semi-arid meadow steppe

Rising atmospheric CO2 and temperature are altering ecosystem carbon cycling. Grasslands play an important role in regional climate change and global carbon cycle. Below-ground processes play a key role in the grassland carbon cycle because they regulate …     

Selective catalytic oxidation of ammonia to nitrogen over orderly mesoporous CuFe2O4 with high specific surface area

Orderly mesoporous CuFe2O4 spinel-type mixed oxide with high specific surface area was prepared successfully by a hard-template method in which KIT-6 mesoporous silica was selected as the hard template. The KIT-6 hard template and CuFe2O4 samples were charac- terized by X-ray diffraction, X-ray photoelectron spec- troscopy, X-ray fluorescence, transmission electron microscopy, scanning electron microscopy, nitrogen physisorption, and hydrogen-temperature programmed reduction. The KIT-6 hard template had perfect crystalli- zation and ordered mesoporous structure with a probable pore distribution of about 9.1 nm, large enough to be filled by the spinel precursor. The mesoporous CuFe2O4 spinel oxide synthesized inside the KIT-6 mesopores had a rela- tively small pore size （4.3 nm）, orderly arrangement, and high specific area （194 m2/g）. The catalytic activity of the mesoporous CuFe2O4 was tested for the selective oxidation of ammonia to nitrogen. The conversion of ammonia reached nearly 100 % at 300 ℃with a nitrogen selectivity as high as 96 %. The nitrogen selectivity remained high with increasing temperature and even maintained a value of 80 % at 600 ℃.     

Fluxes of carbon dioxide and methane from swamp and impact factors in Sanjiang Plain,China

Incomplete decomposition of organic matter results in the accumulation of the carbon and other nutriments in wetlands. The wetland ecosystem gains a large amount of carbon from atmosphere CO2 by photosynthesis, and it loses much of which back into the atmosphere as CO2 and CH4 emission through the decomposition and respiration. Climate change, such as global warming and reduction of precipitation could drive the wetlands from carbon sink to source[1,2]. Wetland plays an important role in car…     

Observation of small-scale processes over shelf break in the East China Sea

The turbulent dissipation along with temperature and salinity was measured on board R/V Dong Fang Hong 2 over the shelf break of the East China Sea from March 7 to 9, 2004. Applying the Turner angle, it is found that the ＇diffusive＇ double diffusion, salt-fingering, and stable stratification coexist in the upper water column of about 50 m. Below that depth, there exists weak salt-fingering. The turbulent dissipation rates are enhanced along the ray paths of M2 internal tides emanating from the shelf break with values ranging from 1.0×10^-9 W·kg^-1 to 1.2×10^-6 W·kg^-1. The corresponding diapycnal mixing rates are from 1×10^-6 m^2· s^-1 to 1×10^-2 m^2· s^-1. The spatially averaged mixing rate over the whole observation section is 2.3×10^-3 m^2· s^-1, which is much larger than 1×10^-5 m^2·s^-1 of the background diapycnal mixing rate in the open ocean.     

Micro-arc oxidization fabrication and ethanol sensing performance of Fe-doped TiO<Subscript>2</Subscript> thin films

In-situ pure TiO₂ and Fe-doped TiO₂ thin films were synthesized on Ti plates via the micro-arc oxidation (MAO) technique. The as-fabricated anatase TiO₂ thin film-based conductometric sensors were employed to measure the gas sensitivity to ethanol. The results showed that Fe ions could be easily introduced into the MAO-TiO₂ thin films by adding precursor K₄(FeCN)₆·3H₂O into the Na₃PO₄ electrolyte. The amount of doped Fe ions increased almost linearly with the concentration of K₄(FeCN)₆·3H₂O increasing, eventually affecting the ethanol sensing performances of TiO₂ thin films. It was found that the enhanced sensor signals obtained had an optimal concentration of Fe dopant (1.28at%), by which the maximal gas sensor signal to 1000 ppm ethanol was estimated to be 7.91 at 275°C. The response time was generally reduced by doped Fe ions, which could be ascribed to the increase of oxygen vacancies caused by Fe³⁺ substituting for Ti⁴⁺.     

SiO2/IDT/AlN/Diamond多层结构中声表面波传输特性的有限元分析

基于COMSOL软件对SiO2/IDT/AlN/Diamond多层结构中声表面波(surface acoustic wave,SAW)传输特性进行有限元(finite element method,FEM)分析.深入分析了多层结构中声波的色散特性,直观地展现了表面波向漏表面波的转化过程,研究了Al电极层厚度和SiO2缓冲层厚度对声表面波的影响.基于微加工工艺研制出一系列不同结构的声表面波谐振器,并对其频率响应特性进行了测试.测试结果与仿真结果基本一致,其中,1阶模式的声表面波表现出较好的应用潜力,可用于声表面波滤波器的研制.     

A new technique for synthesis of 2,4-dichloro-thieno[3,2-d]pyrimidine

3-Amino-2-methoxycarbonylthiophene used as the main raw material,an intermediate(thiofuran siamese) 2,4-dichloro-thieno[3,2-d]pyrimidine was synthesized.The prod-uct was characterized by nuclear magnetic resonance(NMR).The first step yield was 84%(190 ℃) and the second step yield was 81.4%(105 ℃,m(intermediate):m(phosphorus oxychloride) = 1:6.4).The raw product was refined with a unique refining process,which can enhance the purity up to 99.5% to meet the requirement of condi-tions for the development and research of thiofuran siamese as a new medicine of anticarcinogen.Contrasted with the traditional technique,this process featured with cheap raw materials,possible for solvent recovery and reuse,low comprehensive cost,and suit-able for production on certain scale.     

α-(2,5-二甲基-3,4-二乙酰基吡咯基)萘的合成和晶体结构

 在酸性介质中,3,4-二乙酰基-2,5-己二酮与萘胺作用,合成得到了α-(2,5-二甲基-3,4-二乙酰基吡咯基)萘,用IR,1H-NMR,MS,HRMS对其进行了表征,并用X射线衍射测定了α-(2,5-二甲基-3,4-二乙酰基吡咯基)萘的晶体结构.该晶体属三斜晶系,P1空间群,晶体学数据为:a是0.8045(1)nm,b是1.0018(1)nm,c是2.0757(2)nm,α是80.09(1)°,β是82.66(1)°,γ是83.81(1)°,V是1.6281(3)nm³,Z是4,M_r是305.36,D_c是1.246×10³kg/m³,μ(M_oK_α)是0.080mm^-1,F(000)是648,在I>2σ(I)的独立可观测衍射点为3669个,最终偏差因子R是0.0406,W_R是0.0962.