纳米Al2O3颗粒对Cu-Al2O3性能的影响

采用溶胶-凝胶法制备纳米Al₂O₃颗粒,通过粉末冶金法制备氧化铝铜（Cu-Al₂O₃）。采用X射线光电子能谱仪、扫描电子显微镜、洛氏硬度仪和涡流计分别测试了Cu-Al₂O₃的结合能、微观组织、硬度和导电率。结果表明：随Al₂O₃颗粒含量的增加,Cu-Al₂O₃的硬度先升高后降低,当Al₂O₃颗粒的质量分数达到0.084%时,Cu-Al₂O₃的硬度达到最大值75.73（HRB）。Cu-Al₂O₃的导电率随着Al₂O₃颗粒含量的增加逐渐下降。Al₂O₃颗粒的质量分数为0.084%时为最佳值,Cu-Al₂O₃的硬度达到最大值,导电率达到69.1% IACS。     

氧化吸收法同步脱除燃烧烟气中SO2，NOx和CO2的化学热力学及其评价

湿化学法同步脱除烟气中气态污染物是燃烧源大气污染控制的重要方法之一,为探究采用不同氧化吸收策略同时脱除燃烧烟气中SO_2,NO_x和CO_2的可行性,基于化学热力学原理,分析了9种联合氧化吸收策略的性能,具体的氧化吸收策略包括:H_2O_2-NH_3·H_2O,H_2O_2-MDEA,H_2O_2-NaOH,O3-NH_3·H_2O,O3-MDEA,O3-NaOH,NaClO_2-NH_3·H_2O,NaClO_2-MDEA和NaClO_2-NaOH,并提出新的动态加权法对其性能进行综合评价。结果表明:上述所有策略均具有SO_2,NO_x和CO_2捕获的可行性。O3-NaOH,NaClO_2-MDEA和NaOH做吸收剂的氧化吸收溶液分别对单一脱硫、脱硝和脱碳效果最好。当综合考虑同步脱除SO_2,NO_x和CO_2时,NaClO_2-MDEA优于其他策略,其结果可为燃烧烟气中的气体污染物的联合脱除提供参考。     

Carbon and nitrogen stable isotope analyses of mammal bone fossils from the Zhongba site in the Three Gorges Reservoir region of the Yangtze River,China

Based on AMS ¹⁴C dating data, carbon and nitrogen isotope analyses were conducted on mammal bone collagen of deer, cattle and pigs from the Zhongba site in the Three Gorges Reservoir region of the Yangtze River. These analyses were conducted to reconstruct palaeodiets of mammals, palaeoecology, palaeoenviroment and previous human activities in the study area. Results show that the collagen loss of bone did not change the in vivo isotopic composition of carbon and nitrogen stable isotopes, and most of the bone fossils were well preserved. The bone collagen of samples from deer had a mean δ¹³C of -23.1‰ and a mean δ¹⁵N of 4.7‰, suggesting that deer subsisted in a closed habitat and fed on branches and leaves. The bone collagen of cattle had a mean δ¹³C of –19.6‰ and a mean δ¹⁵N of 5.2‰, which indicates that cattle subsisted in an open habitat and fed on grasses and stems. The δ¹³C values show that both deer and cattle fed on C₃ plants and lived in the same ecosystem, but the t-test results show that deer δ¹³C and δ¹⁵N values were both more negative than those of cattle, indicating that they inhabited different niches. The δ¹³C and δ¹⁵N values of cattle partially overlapped those of deer, suggesting some competition in diets between them. The t-tests show that the δ¹³C and δ¹⁵N values of pigs were more positive than those of cattle and deer, which signifies that pigs occupied a higher trophic level compared to cattle and deer. The wide range of pig δ¹³C values demonstrates that pig trading had been taking place from early Neolithic Age to late Bronze Age. There were no significant differences in deer δ¹³C and δ¹⁵N values among different archaeological periods, making it clear that climatic, ecological and environmental conditions were kept relatively stable from 2200 to 4200 a BP. This stability may have been responsible for the extensive and complete cultural layers at the Zhongba site. The minimum number of samples required to estimate the mean δ¹³C values of deer, pigs and cattle are 8, 73 and 16, respectively, and for mean δ¹⁵N values of deer, pigs and cattle, the minimum numbers are 4, 5 and 6, respectively.     

Turbidite and bottom-current evolution revealed by anisotropy of magnetic susceptibility of redox sediments in the Ulleung Basin,Sea of Japan

Anisotropy of magnetic susceptibility(AMS) from above and below 7.31 m in a core from the southern Ulleung Basin shows clear differences on an equal area projection of the lower hemisphere.Rather concentrated steep inclination of K 3 and horizontal inclination of K 1 and K 2(K1 ≥K2 ≥K3) are located within the upper part,and the latter two axes lie perpendicular to each other near the bedding plane.In contrast,random distribution of the three axes and extremely high value of shape parameters(Q=(K1-K2)/[(K1+K2)/2-K3]) are evident in the lower part,indicating complete destruction of the original sedimentary structure.This result is consistent with data from X-radiographs,which show numerous conglomerates,distortions and cleavages in the lower part.According to age models by Liu et al.(2010) and Zou et al.(2010),the bottom age at 7.31 m is 48 cal ka BP,and the time domain is discussed below.The degree of AMS(P) is low,1-1.08,and linearly related to the foliation(F)(R2 =0.95,N=176).The relationship between F and linearity(L) implies oblate aligning patterns that are typically sedimentary in origin.At least five redox couplets were found with the aid of S ratios and other rock magnetic parameters,and in most cases,the original signals of climate survived early diagenesis.The paleomagnetically reoriented AMS show corresponding changes with millennial events in the last 48 cal ka.Clearly tilted K 3 directions and reduction of P and F occurred within DO1-BA warm events,when melt water pulse 1A nd the YD cold event took place.The turbulent conditions therein,synchronous with coarsening of sediments,provide evidence of strong bottom currents and possible directional changes,as evidenced by different K3 tilting directions.A NE current direction in the last 4.5 cal ka is consistent with in situ measurements of bottom currents.Responses of AMS,mainly to climatic modulation,show on the one hand,the limited influence of diagenesis on rock magnetic signals and,on the other hand,the dramatic change of hydrodynamic conditions and terrigenous inputs during rapid sea level rise during the last deglaciation.     

中国低纬高原平流层NOx分布及其与O3的关系

 利用1992年9月～2005年8月的HALOE资料,对我国低纬高原地区上空平流层中NO_x,O₃等大气痕量气体的混合比垂直变化进行了研究,并对本区域不同高度上NO_x混合比与全球同纬度进行了比较,同时对NO_x随时间的演变特征,NO_x的变化周期及NO_x与O₃的相关关系进行了分析.结果表明:①NO_x,O₃混合比先随高度增加,到极值时又逐渐减小;在极值高度上,各个季节NO_x,O₃的混合比值都是夏季最高,冬季最低;②在5 hPa以上,春季NO混合比与同纬度地区的纬圈平均相比其值更高,各个季节NO₂混合比的总体趋势都要比同纬度地区低;③在100,10 hPa和1 hPa上,NO_x混合比随时间变化的总体趋势是各不相同的;④NO_x具有准2 a周期变化;⑤在10 hPa附近,NO_x与O₃存在较明显的反相关关系.     

Synthesis, conductivity and photosensitivity of 2-D conjugated polymers of metalporphyrazine with sulfur bridges

The title polymers PMS₈Pz, M=Mn^II, Fe^II, Co^II, Ni^II, Cu^II, Zn^II, were synthesized by reaction of 2, 3, 5, 6-tetracyano-1, 4-dithiin with corresponding metal salts, respectively. The structure and properties of these polymers were characterized by elemental analysis, transmission electron microscope, DTA, IR, UV-Vis, fluorescence and EPR spectra. It has been found that these conjugated polymers have the property of intrinsic semiconductor. The conductivity σ_298K of these polymers is in the range of 10⁻⁹≈10⁻³ S·cm⁻¹ under pressure 10.63 MPa and incrementals in the metal order Mn<Co<Fe<Zn<Cu<Ni. The photosensitivity of the MS₈Pz to the CdS-PVA films is incrementals in the metal order Zn<Mn<Co<Fe<Cu<Ni. Supported by the National Natural Science Foundation of China and by the Approach Fund of State Key Laboratory of Coordination Chemistry in Nanjing University Peng Zhenghe: born in Apr. 22, 1945, Professor     

Effect of Co on the martensitic transformation,crystal structure and magnetization of Ni<Subscript>52.5</Subscript>Mn<Subscript>23.5</Subscript>Ga<Subscript>24</Subscript> based ferromagnetic shape memory alloys

Five(Ni52.5Mn23.5Ga24)100-xCox(x = 0,2,4,6,8) alloys were prepared by arc melting,and the effects of Co addition on the martensitic phase transformation,crystal structure and magnetization were investigated.The phase transformation temperatures Ms,Mf,As and Af are proportional to the content of Co in the(Ni52.5Mn23.5Ga24)100-xCox alloys,which appears to be due to the variation in the valance electron concentration.The Curie temperature is sensitive to the composition of the alloy.As the amount of Co changes,both the Co-Mn exchange interaction and the distance between Mn atoms change.These,in turn,affect the Curie temperature and magnetization behavior of the alloy.The martensite phases in all the alloys are domained in three different orientations,the domain boundary was determined to belong to the family of {112} lattice planes.     

Dashnic-Zusmanovich矩阵线性互补问题误差界的估计

研究P-矩阵的新子类Dashnic-Zusmanovich矩阵线性互补问题的误差界.利用Dashnic-Zusmanovich矩阵M和■=I-D+DM的性质、不等式的性质,以及M矩阵的逆矩阵无穷范数上界的估计式,得到了矩阵M的线性互补误差界的估计式.     

均匀分散的纳米银/介孔氮化碳复合微粒的协同光催化性能研究

为了有效还原污染水中的硝基化合物和光解水制氢,采用浸渍法制备纳米银/介孔石墨相氮化碳(Ag/mpg-C_3N_4)复合微粒,继而通过简单吸附法制备Ag/5-OH-ZnTPP/mpg-C_3N_4复合微粒,利用BET,SEM,XRD和XPS等表征方法对所制备复合微粒的形貌、微观结构和组成进行测试,结果显示,介孔石墨相氮化碳(mpg-C_3N_4)呈多孔片层状,纳米银粒子(AgNPs)均匀分散于mpg-C_3N_4表面及片层间。通过UV-vis DRS,PL和PT等表征方法对Ag/5-OH-ZnTPP/mpg-C_3N_4复合微粒的光电性能进行测试,结果表明,AgNPs的引入和锌卟啉的表面敏化作用提高了mpg-C_3N_4基体对可见光的利用率。选用对硝基苯酚还原和光解水制氢为模型反应,经贵金属沉积改性及锌卟啉表面敏化改性后显著提高了mpg-C_3N_4基体的光催化活性。因此,Ag/5-OH-ZnTPP/mpg-C_3N_4复合微粒对4-NP的还原反应及光解水制氢具有高效催化活性。     

垂直振动激励下不同状态物料的宏观混合效果

为了解振动混合应用于不同状态被混物料时,物料状态对宏观混合效果的影响,采用垂直振动混合方式对液-液体系、固体填料黏合剂体系和颗粒体系进行混合研究,观测和记录混合发展过程。在频率为60 Hz、振幅为2 mm的工况下对甘油水溶液、高黏态火炸药模拟物、铝粉颗粒进行振动混合研究。结果表明,不同状态物料振动混合强度影响因素不同;对于液-液混合体系,液体黏度是影响其混合强度的主要因素,黏度越小混合越剧烈;对于颗粒体系,流散性是影响其混合强度的主要因素,流散性越好混合越剧烈;对于固体填料黏合剂体系,液相组分的黏度和固相组分的流散性共同影响混合强度,固体填料黏合剂体系的混合是基于物料的缠结和撕裂来实现的。     

Synthesis and electrochemical properties of LiNi0.8Al0.2−xTixO2 cathode materials by an ultrasonic-assisted co-precipitation method

A new co-precipitation route was proposed to synthesize LiNi_0.8Al_0.2−xTi_xO₂ (x=0.0-0.20) cathode materials for lithium ion batteries, with Ni(NO₃)₂, Al(NO₃)₃, LiOH·H₂O, and TiO₂ as the starting materials. Ultrasonic vibration was used during preparing the precursors, and the precursors were protected by absolute ethanol before calcination in the air. The influences of doped-Ti content, calcination temperature and time, additional Li content, and ultrasonic vibration on the structure and properties of LiNi_0.8Al_0.2−xTi_xO₂ were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and charge-discharge tests, respectively. The results show that the optimal molar fraction of Ti, calcination temperature and time, and additional molar fraction of Li for LiNi_0.8Al_0.2−xTi_xO₂ cathode materials are 0.1, 700°C, 20 h, and 0.05, respectively. Ti doping facilitates the formation of the α-NaFeO₂ layered structure, and ultrasonic vibration improves the electrochemical performance of LiNi_0.8Al_0.2−xTi_xO₂.     

Antibacterial activity and structure-activity relationships of Schiff bases on <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> by microcalorimetry

The growth of Staphylococcus aureus under the action of six kinds of Schiff bases(A,B,C,D,E,F) was studied by means of microcalorimetry. Growth constant k and inhibition ratio I were calculated. Also,the antibacterial activity,the action characteristics and the structure-activity relationships of the compounds on S. aureus were analyzed. Results indicate that B,F show good antibacterial activity(IC50:293.6 mg · L-1 and 307.8 mg · L-1) ,D,E show moderate antibacterial activity(IC50:966.3 mg · L-1 and 1 126.7...     

四氧化三铁-石墨烯复合芬顿催化剂用于染料脱色的研究

芬顿催化是污水处理中最常用的技术之一,但是传统芬顿试剂需要对水体进行酸化并造成大量亚铁离子浪费.本文用水合肼还原法制备了四氧化三铁-石墨烯复合芬顿催化剂(Fe3O4-G),测试其催化脱色甲烯蓝的活性.Fe3O4-G样品用透射电镜、X射线光电子能谱和红外光谱等表征.Fe3O4-G能催化双氧水分解氧化脱色甲烯蓝.Fe3O4-G在pH3.5~9.5范围内均能有效催化脱色甲烯蓝,最佳pH为8.5.Fe3O4-G的催化活性几乎不受溶剂的影响,加入自由基淬灭剂叔丁醇对脱色也没有明显抑制.Fe3O4-G在较高的温度下催化能力更强,增大双氧水用量也能促进脱色反应.     

生态营林桉树人工林林木生长动态分析

为阐明轮伐期内不同类型桉树(Eucalyptus spp.)人工混交林的生长动态特征及变化规律,选择于2012年在中国林业科学研究院热带林业实验中心青山实验场采用生态营林制度营造的桉树×降香黄檀混交林(Eucalyptus×Dalbergia odorifera,MED)、桉树×望天树混交林(Eucalyptus×Parashorea chinensis,MEP)、桉树×红锥混交林(Eucalyptus×Castanopsis hystrix,MEC)和桉树纯林(PEU)为研究对象,设置固定监测样地,基于桉树第一轮伐期内的3次林分调查(2014、2016、2018年),分析不同混交林桉树和珍贵树种的胸径、树高、单株材积和林分蓄积量动态变化特征。结果表明,监测期内,4种林分类型林木胸径、树高、单株材积和林分蓄积量均随林龄显著增加;混交林中降香黄檀、红锥及望天树均可显著促进桉树胸径、树高、单株材积及林分蓄积量的生长,促进作用大小表现为MED>MEC>MEP;不同混交类型中珍贵树种的胸径、树高、单株材积及林分蓄积量均表现为MEC>MEP>MED,林分总蓄积量表现为ME...     

水溶性磁性Fe_3O_4纳米粒子对小麦生长影响的研究

水溶性磁性Fe_3O_4纳米颗粒由于其良好的生物相容性、超顺磁性等特征,在生物领域常被用来作为磁性载体材料,其广泛的生产和应用增加了它们在环境中释放的可能性,需对其环境生物安全性进行评价.首先合成了水溶性磁性Fe_3O_4纳米纳米粒子,并用透射电子显微镜和马尔文粒度分析仪对其进行形貌分析和表征.然后在不同的浓度下(0、0.72、1.44、3.6 mg/mL)研究了水溶性磁性Fe_3O_4纳米粒子对小麦生长的影响,结果显示随着浓度的增加,磁性Fe_3O_4纳米纳米粒子对小麦生长的抑制越明显,造成生长抑制和根结构损伤.结果证明了水溶性磁性Fe_3O_4纳米颗粒对小麦植物存在一定的生物毒性,其环境排放应该严格限制.     

广西主要贝类养殖区重金属含量分布特征及污染评价

为探究广西主要贝类养殖区重金属含量的分布状况及污染水平,依据2016-2018年广西主要贝类养殖区的海水、表层沉积物及生物体中重金属元素(Cu、Pb、Zn、Cd、Hg、As)的调查分析数据,分别采用单因子污染指数(P_i)法、地积累指数(I_geo)法和生物富集系数(Bioconcentration Factors, BCF)对养殖区重金属进行污染评价。结果表明：海水中各重金属的含量分布为Zn>Cu>As>Pb>Cd>Hg,污染程度为Cu>Hg>Zn=Pb>Cd>As;沉积物中各重金属的含量分布为Zn>Cu>Pb>As>Cd>Hg,污染程度为As>Cd>Pb>Hg>Cu=Zn;近江牡蛎(Crassostrea rivularis)贝体中各重金属的含量分布为Zn>Cu>Cd>As>Pb>Hg,污染程度为Zn>Cu>Cd>Pb>Hg>As,生物富集能力为Zn>Cu>Cd&g...     

Relation between standard entropies of elements and electronic configurations

A close relationship has been found between the standard entropies of elements and their electronic configurations. Based on the positions of elements in the periodic table and the variation in the standard entropies of elements, the standard entropies of elements can be expressed as the sum of two functions:S ⁰=f(N) +f(E), whereS ⁰ is the standard entropy of an element,N the principal quantum number, andE the number of outermost electrons. And the specific formula isS ⁰ = 99.05N ^1/3 + [0.32(sp −4)⁴ -119.76] + [-56.56N ^1/3+ 0.70(sd ∼-7)² −42.12] + [−11.95 × 10⁻⁴(df-8)⁻⁴ -105.70], wheresp, sd, df are the numbers of the outermost electrons in thesp, sd, df regions of the periodic table, respectively. This formula helps reveal the essence of the standard entropies of elements and deepens our understanding of the thermodynamic characteristics of compounds.     

Influence of Characteristics on Bending Strength of Layered Steel Fiber Reinforced Concrete

The influence of two main characteristics of steel fiber, the aspect ratio （Df） and volume fraction （ρf）, on the bending strength of Layered Steel Fiber Reinforced Concrete （LSFRC） is investigated by using orthogonal test. Via the variance analysis on the experimental results and trend analysis on the two characteristics, Df is found significantly related to the bending strength of LSFRC. The influence ratio is 63.3%. The bending strength of LSFRC increases if Df increases, makes better when Df reaches 100. ρf has ordinary influence on the bending strength of LSFRC. The influence ratio is 29.2%. Other characteristics, such as the shape of steel fiber and the mix proportion, have less influence. The best ρf contributing to the bending strength of LSFRC is 1.5 %. If ρf is greater than 1.5%, it has negative influence on the bending strength of LSFRC. So, ρf makes a limited contribution to the bending strength of LSFRC.     

Plasma structures inside boundary layers of magnetic clouds

Magnetic cloud is an important interplanetary dis-turbance structure generated by the coronal mass ejections(CMEs), it has been widely investigated[1—5] since it wassuggested by Burlaga et al[1]. However, the boundary ofthe magnetic cloud has no objective definition yet. Manyobservational signatures have been used to identify thecloud boundary[6—13], as Burlaga[14] indicated, there is noconsistency among these various approaches. The problemof the BLs was not been solved because of its co…     

Effects of nitrogen sources and glucose on the consumption of ethylene and methane by temperate volcanic forest surface soils

There is limited knowledge with regard to the consumption of ethylene (C2H4) and methane (CH4) in volcanic forest soils containing low microbial carbon-to-organic carbon ratio, and to the responses of both consumptions to nitrogen and carbon additions. Temperate volcanic forest surface soils under three forest stands (e.g. Pinus sylvestris L., Cryptomeria japonica and Quercus serrata) were used to compare CH4 and C2H4 consumption by forest soils, and to study the effects of nitrogen sources and glucose on both consumptions. There was a good parallel between CH4 and C2H4 consumption by for- est soils, but mineralization reduced CH4 consumption rather than C2H4 consumption in forest soils, particularly in a Pinus forest soil. The stimulatory effect of glucose addition on both CH4 and C2H4 consumption by forest soils was increased by increasing the pre-incubation period after glucose addi- tion, and a largest stimulation occurred in the Pinus forest soil. The addition of KNO3-N at the rate of 100 μg·g1 significantly reduced the consumptions of both C2H4 and CH4 by forest soils (P≤0.05). In the presence of urea plus dicyandiamide, the consumption rates of C2H4 and CH4 by forest soils were higher than those in the KNO3-N and urea-N treated soils at the same N rate (P≤0.05), but were similar to those of the control. Hence, under experimental conditions, there was a strong inhibitory effect of NO3 rather than NH4 addition on the CH4 and C2H4 consumption in these forest soils. When amount of the added NO3-N increased up to more than 2―3 times the soil initial NO3-N concentrations, both C2H4 and CH4 consumption rates were reduced to 10%―20% of the rates in soils without nitrate addition. By comparing the three forest stands, it was shown that there was a smallest effective concentration of the added nitrate that could inhibit C2H4 and CH4 consumption in the Pinus forest soil, which indicated that C2H4 and CH4 consumption of the soil was more sensitive to NO3-N addition.