陕西省榆林市冬季PM_(10)和PM_(2.5)的污染特征

为了探讨陕西省榆林市冬季大气颗粒物的污染特征,2013年11月对榆林市3个采样点进行可吸入颗粒物(PM10)和细颗粒物(PM2.5)同步观测,利用离子色谱法和热光分析法测定PM10和PM2.5中无机水溶性离子和碳组分的浓度。结果表明:3个采样点PM10和PM2.5日均质量浓度分别为162、74μg/m3,颗粒物浓度由大到小的采样点为环保旧站、实验中学和环保大厦;PM10中有机碳和元素碳的质量浓度空间分布与颗粒物的相同;PM2.5中有碳组分在环保旧站和实验中学的浓度接近,都大于环保大厦的;无机离子中SO42-和Ca2+浓度最大;PM10与PM2.5整体偏碱性,亏损的阴离子主要是CO32-;扬尘在PM10中的比例远远大于其他组分;PM2.5中碳组分含量较大,其次是土壤尘、硫酸盐、氯化物和硝酸盐等;治理PM10和PM2.5污染应以加强扬尘控制和减少燃煤污染物排放为主。     

The Development of a Mathematical Approximation Technique to Determine the Mass Median Aerodynamic Diameter (MMAD) and Geometric Standard Deviation (GSD) of Drug Particles in an Inhalation Aerosol Sprat

The aerodynamic diameter of an airborne particle is the key property in determining its respiratory deposition. Two particles may differ in their shape, size, and/or density and still be aerodynamically indistinguishable because they have similar behavior in a moving airstream. A cascade impactor has been used to measure the range of aerodynamic diameters for drug particles in an aerosol spray product. The two terms associated with aerodynamic particle sizing are Mass Median Aerodynamic Diameter (MMAD) and the Geometric Standard Deviation (GSD). Both terms are determined from the visual fit of a straight line to data manually plotted on log-probability paper. The plotting of this data is a time consuming activity and the fit of the line to the data can be very subjective.

Although this technique is an excellent candidate for computerization, it cannot be done directly since the probability axis is an integral function not easily adaptable to the computer packages generally used in the laboratory. A mathematical approximation has been developed that in effect “linearizes” the probability axis. The mathematical relationship (a fifth degree polynomial expression) when incorporated into a general computer program allows for the direct computation of the two aerodynamic terms. Since the subjectiveness of manually plotting the data and fitting the line are removed, the results obtained are potentially more accurate. Also, the results are obtained more quickly with significantly less effort. This paper explores the development of the mathematical relationship and provides a comparison of values obtained by both the manual and computer methods.     

Properties, Microstructures and Precipitate Morphology of Hot-rolled Interstitial-Free (IF) Steel Sheets

［1］Klaus Hulka: Stahl und Eisen, 1990, (9), 450. ［2］Zuocheng WANG: Ph.D. Thesis, University of Science and Technology Beijing, 1994. (in Chinese) ［3］Zuocheng WANG, Zongren WANG and Xianjin WANG: Mater. Sci. Tech., 1997, 5(2), 129. (in Chinese) ［4］Zuocheng WANG and Xianjin WANG: Special Steel,1999, 20(3), 23. (in Chinese)     

Morphology, mechanical and thermal properties of graphene-reinforced poly(butylene succinate) nanocomposites

Graphene nanosheets (GNSs) reinforced poly(butylene succinate) (PBS) nanocomposites are facilely obtained by a solution-based processing method. Graphene nanosheets, which are derived from chemically reduced graphite oxide (GO), are characterized by AFM, TEM, XRD and Raman spectra. The state of dispersion of the GNSs in the PBS matrix is examined by SEM observations that reveals homogeneous distribution of GNSs in PBS matrix. A 21% increase in tensile strength and a 24% improvement of storage modulus are achieved by addition of 2.0 wt% of GNS. The electrical conductivity and thermal stability of the graphene-based nanocomposite are also improved. DSC measurement indicates that the presence of graphene sheets does not have a remarkable impact on the crystallinity of the nanocomposites. Therefore, the high performances of the nanocomposites are mainly attributed to the uniform dispersion of GNSs in the polymer matrix and strong interfacial interactions between both components.     

西安市春季大气颗粒物PM_(2.5)与PM_(10)的特征

2010年4月在西安市区4个点使用低流量采样器同步连续采集2周(24 h/d)细颗粒物PM2.5和可吸入颗粒物PM10样品,分别利用热光碳分析仪、离子色谱和X射线荧光光谱仪分析其含碳组分(有机碳和元素碳)、水溶性无机离子(NH4+、Na+、K+、Ca2+、Mg2+、F-、Cl-、SO42-、NO3-)和元素Ca、Fe等浓度。结果表明,沙尘暴期间,PM10的质量浓度是PM2.5的3倍,PM2.5和PM10中有机碳浓度大于正常天气的,SO42--NO3--NH4+浓度急剧减小,明显小于正常天气,这与干燥沙尘暴的稀释作用有关;后向轨迹、气溶胶指数和Ca与Fe元素质量浓度比验证了沙尘暴颗粒来源西部戈壁沙尘和黄土高原;阴阳离子平衡计算显示沙尘事件颗粒物呈碱性,阴阳离子差异估算的CO32-含量与Ca2+具有强相关性,表明沙尘暴颗粒以CaCO3为主。     

(Sr,Pb)TiO3超微粉体的制备和性质

应用草酸盐共沉淀法制备（Ｓｒ，Ｐｂ）ＴｉＯ３超细粉体，分析了共学淀产物的热分解过程，确定了昌化温度和煅烧条件，同时，测量了粉示的晶粒尺寸，标定了材料的晶体结构，试验了粉体的烧结条件。     

Development of a Tunable, Narrow-Linewidth, CW 2.066-mum Ho:YLF Laser for Remote Sensing of Atmospheric CO(2) and H(2)O

A smoothly tunable, narrow-linewidth, cw, 32-mW, 2.066-mum Ho:YLF laser was constructed and used for the first time in preliminary spectroscopic measurements of atmospheric CO(2) and H(2)O. The laser was constructed with a 4.5-mm-long, TE-cooled, codoped 5% Tm and 0.5% Ho yttrium lithium fluoride crystal (cut at Brewster's angle) pumped by an Ar(+)-pumped 500-mW Ti:sapphire laser operating at 792 nm. Intracavity etalons were used to reduce the laser linewidth to approximately 0.025 cm(-1) (0.75 GHz), and the laser wavelength was continuously and smoothly tunable over approximately 6 cm(-1) (180 GHz). The Ho:YLF laser was used to perform spectroscopic measurements on molecular CO(2) in a laboratory absorption cell and to measure the concentration of CO(2) and water vapor in the atmosphere with an initial accuracy of approximately 5-10%. The measurement uncertainty was found to be due to several noise sources, including the effect of asymmetric intensity of the laser modes within the laser linewidth, fluctuations caused by atmospheric turbulence and laser beam/target movement, and background spectral shifts.     

Morphology and molecular orientation in sexithiophene and N,N′-bis (n-octyl)-dicyanoperylenediimide heterostructures

We report on the growth mode of N,N′-bis (n-octyl)-dicyanoperylenediimide (PDI-8CN₂) on sexithiophene (T6) thin films, studied with different structural, morphological and optical techniques. We aim to individuate the most favorable conditions for the realization of heterostructure devices. The crystalline quality was established by X-ray patterns and Atomic Force Microscopy (AFM) images, and found to be generally high. The anisotropic optical constants extracted from ellipsometry measurements shed light on the mean molecular orientation in the PDI-8CN₂ film. AFM images evidence two different growth modes: at T6 thickness less than 2 monolayers (ML), the growth of PDI-8CN₂ on T6 is favored with respect to SiO₂, while, at higher thickness (2-6 ML), the situation is reversed. An optimum T6 underlayer thickness of approximately 1 ML provides the best quality of PDI-8CN₂ layer corresponding to the highest island dimension, the highest molecular order parameter, and the lowest roughness. Spectrum broadening was observed for extinction coefficient of PDI-8CN₂ in the heterostructures, as compared with a sole material film, and explained by two effects: increase in molecular disorder and formation of charge transfer complexes.     

聚(3-羟基丁酸酯-co-4-羟基丁酸酯)/酶解木质素共混材料的制备及性能

双螺杆熔融共混制备了全生物降解的聚(3-羟基丁酸酯-co-4-羟基丁酸酯)(P3HB4HB)/纤维素酶解木质素(CEL)共混物,分别用热重分析、拉伸弯曲试验、冲击试验、扫描电镜(SEM)考察了CEL含量对共混物热学、力学性能及微观形貌的影响。研究发现,CEL的加入增强了材料的热稳定性,也提高了材料的模量,但断裂伸长率、拉伸强度、弯曲强度和冲击强度平缓降低,当CEL的质量分数为20%CEL,拉伸、弯曲、冲击三种强度的保持率都大于93%;SEM显示,P3HB4HB和CEL相容很好。CEL填充P3HB4HB不仅能降低材料成本,还能对材料的热学、力学性能保持较好或起改善作用,CEL最宜添加的质量分数为20%。     

STEP (Statistical Test of Equivalent Pathways) analysis: a mass spectrometric method for carbohydrates and peptides

We have recently developed a new mass spectrometry method, the STEP (statistical test of equivalent pathways) analysis that uses ion abundances in two tandem mass spectrometry experiments to obtain genealogy information about product ions present in mass spectra. The method requires minimal sample, and it can be performed using a conventional quadrupole ion trap mass spectrometer. To obtain genealogy information, STEP ratios are calculated by comparing the relative abundances of product ions in two MS/MS experiments. These ratios are directly related to the origin of the product ions. Product ions that result directly from the precursor ion always have STEP ratios that are 相似文献   

Morphology, structural and optical characterization of electron beam evaporated bromoaluminium phthalocyanine (BrAlPc) thin films

Bromoaluminium phthalocyanine (BrAlPc) thin films have been deposited onto pre-cleaned glass substrates by electron beam evaporation technique. Thin films have been characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and optical absorption (UV–Vis) spectra. XRD studies of BrAlPc thin film deposited at room temperature shows the indication of the α-phase. FESEM images have shown that the most of particles are spherical in shape with an average size about 26–34 nm. Using UV–Visible spectra over the wavelength range 300–800 nm, the optical band gap, absorption coefficient and extinction coefficient of BrAlPc thin films are evaluated. The optical absorption measurements of thin films show that the absorption mechanism is due to direct transition.     

Atmospheric concentrations, dry deposition and air-soil exchange of polycyclic aromatic hydrocarbons (PAHs) in an industrial region in Turkey

Concurrent ambient air and dry deposition samples were collected during two sampling periods at the Aliaga industrial region in Izmir, Turkey. Sigma 15-PAH (particulate+gas) concentrations ranged between 7.3 and 44.8 ng m(-3) (average+/-S.D., 25.2+/-8.8 ng m(-3)) and 10.2-71.9 ng m(-3) (44.1+/-16.6 ng m(-3)) in summer and winter, respectively. Winter/summer individual ambient PAH concentration ratios ranged between 0.8 (acenaphthene) and 6.6 (benz[a]anthracene) indicating that wintertime concentrations were affected by residential heating emissions. In contrast to the ambient concentrations, summation operator(15)-PAH particle dry deposition fluxes were higher in summer (5792+/-3516 ng m(-2)day(-1), average+/-S.D.) than in winter (2650+/-1829 ng m(-2)day(-1)), probably due to large particles from enhanced re-suspension of polluted soil particles and road dust. Average overall dry deposition velocity of PAHs calculated using the dry deposition fluxes and particle-phase concentrations was 2.9+/-3.5 cm s(-1). summation operator(15)-PAH concentrations in soils taken from 50 points in the area ranged between 11 and 4628 microg kg(-1) in dry weight. The spatial distribution of these concentrations indicated that the urban Aliaga, steel plants, the petroleum refinery, and the petrochemical plant are the major Sigma 15-PAH sources in the area. Fugacity calculations in air and soil showed that the soil acts as a secondary source to the atmosphere for low molecular weight PAHs in summer and as a sink for the higher molecular weight ones in summer and winter.     

Experimental Facilities to Monitor Various Types of Atmospheric Parameters in the Radio and Atmospheric Sciences Division (RASD) of CSIR-National Physical Laboratory

The Indian subcontinent with Himalayan Mountains on northern side, Bay of Bengal on eastern side, Arabian Sea on the western side and Indian Ocean on the southern side presents a unique natural setting with highly variable climatic features. The seasonal variation in North India is highly pronounced whereas in southern India it is moderate, the coastal areas are influenced by cyclones, north western India dominated by western disturbances and desert conditions. Added to these natural influences the rapid urbanization of regions resulted in changing atmospheric conditions leading to sudden occurrence of natural calamities. Prediction of these events requires very reliable climatic models which is a gigantic task. To develop climatic models suitable to our country, huge reliable data base of atmospheric parameters is required. Keeping this objective in view the Radio and Atmospheric Sciences Division of National Physical Laboratory has been engaged in monitoring the atmospheric parameters using various facilities with focus on northern plains. The present paper describes the latest research activities using the existing facilities and future activities and facilities planned in this division.     

热输入对金属基复合涂层中(Nb,Ti)C颗粒分布及性能的影响

目的 热输入对复合碳化物的析出、分布及耐磨性能具有重要影响。然而,目前热输入对碳化物增强金属基复合堆焊层组织结构与性能方面影响的研究较少。因此,需要探究焊接热输入对(Nb,Ti)C增强金属基复合堆焊层组织及耐磨性的影响,明确(Nb,Ti)C复合颗粒在堆焊层的作用机制。方法 采用Ar保护气体进行堆焊涂层的制备,通过调节堆焊电流和电压,研究不同热输入下堆焊层的形貌、组织及耐磨性能。结果 堆焊层中Ti元素与C元素优先发生了原位反应,生成了以TiC为形核中心的(Nb,Ti)C复合碳化物,弥散分布在马氏体基体组织上。随着热输入的增大,析出的(Nb,Ti)C颗粒数量逐渐减少,块状(Nb,Ti)C尺寸也逐渐变小。采用较低的热输入时,堆焊层硬度达到最高,为734.88HV0.5;随着堆焊热输入的增大,堆焊层的显微硬度呈降低趋势。具有较多(Nb,Ti)C的低热输入试样耐磨性能最佳,磨损量为0.80 mg;而具有较少(Nb,Ti)C的高热输入试样产生了严重的黏着磨损,磨损量较低热输入试样增大了约144%。结论 在摩擦磨损过程中,高硬度的(Nb,Ti)C颗粒会对基体起保护作用,可以提升其耐磨性能,且耐磨损性...     

Morphology, Growth Process and Symmetry of {0001} Face on Yb：YAl3（BO3）4 Crystal

The {0001} face develops on the habit of self-frequency doubling laser crystal Yb: YAl3(BO3)4 (YbYAB) only under high growth rate condition, and its morphology is rough. To study the growth mechanism of {0001} face, we have observed the growth morphology on {0001} polishing section by atomic force microscopy (AFM). A series of AFM images captured in different growth durations on the {0001} polishing section reflect the crystal growth process. It is shown that the growth morphology on the {0001} polishing section was rough with many hillocks at the first growth stage, and it can become smooth finally, although the growth morphology on the {0001} face develoFed naturally on YbYAB crystal habit is always rough. On the smooth {0001} surface formed at the last growth stage, there aresome triangular pits. This fact is different from that of hillocks in most crystal growth morphologies. AFM can easilydistinguish the pits or hillocks on the surface, but differential interfere contrast microscopy (DIC) can not do. Theorientation of the triangular pits is just the opposite to the triangular {0001} faces. The chemical etching patternis also composed of this kind of triangular pits. These growth morphology and etching pattern of the {0001} facesshow 3m symmetry, but the point group of YbYAB crystal is 32. The symmetric contradiction between morphologyand point group does not exist for quartz, although whichsurface morphology we can distinguish the right form ormorphology we can not do. The reason for the symmetricand its point group is not known yet.has the same point group as YbYAB. From quartz {0001}left form of the crystal, but from YbYAB {0001} surfacecontradiction between YbYAB {0001} surface morphology and its point group is not known yet.     

Morphology and Thermodynamic Properties of a Copolymer with an Electronically Conducting Block: Poly(3-ethylhexylthiophene)-block-poly(ethylene oxide)

We report on the synthesis and morphology of a block copolymer, poly(3-(2'-ethylhexyl)thiophene)-b-poly(ethylene oxide) (P3EHT-b-PEO), that conducts both electrons and ions. We show that in the melt state the P3EHT-b-PEO chains self-assemble to produce traditional nanoscale morphologies such as lamellae and gyroid. This is in contrast to a majority of previous studies on copolymers with electronically conducting blocks wherein a nanofibrillar morphology is obtained. Our approach enables estimation of the Flory-Huggins interaction parameter, χ. The segregation strength between the two blocks is controlled through the addition of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). For the salt-free sample, the gyroid morphology, obtained in the melt state, is transformed into lamellae below the melting temperature of the P3EHT block. This is due to the "breaking out" of the crystalline phase. For the salt-containing sample, P3EHT-b-PEO has a lamellar morphology in both melt and crystalline states (confined crystallization).