Processible nanostructured materials with electrical conductivity and magnetic susceptibility: Preparation and properties of maghemite polyaniline nanocomposite films

We here present a versatile process for the preparation of maghemite/polyaniline (gamma-Fe2O3/ PAn) nanocomposite films with macroscopic processibility, electrical conductivity, and magnetic susceptibility. The gamma-Fe2O3 nanoparticles are coated and the PAn chains are doped by anionic surfactants of omega-methoxypoly(ethylene glycol) phosphate (PEOPA), 4-dodecylbenzenesulfonic acid (DBSA), and 10-camphorsulfonic acid (CSA). Both the coated gamma-Fe2O3 and the doped PAn are soluble in common organic solvents, and casting of the homogeneous solutions gives free-standing nanocomposite films with gamma-Fe2O3 contents up to similar to 50 wt %. The morphology of the gamma-Fe2O3 nanoparticles are characterized by transmission electron microscopy, UV-vis spectroscopy, and X-ray diffractometry. The gamma-Fe2O3/PAn films prepared from chloroform/m-cresol solutions of DBSA-coated gamma-Fe2O3 and CSA-doped PAn are conductive (sigma = 82-237 S/cm) and superpapamagnetic, exhibiting no hysteresis at room temperature. The zero-field-cooled magnetization experiment reveals that the nanocomposite containing 20.8 wt % gamma-Fe2O3 has a blocking temperature (T-b) in the temperature region of 63-83 K.

A study of cokes used as anodic materials in lithium ion rechargeable batteries

A variety of cokes pretreated at different temperatures are used as anodic materials and their electrochemical characteristics are examined by cyclic voltammetry. It is found that for some cokes such as petroleum coke (preheated at 1300 degrees C), pitch coke (1300 degrees C), needle coke (1900 degrees C), metallurgical coke (1900 degrees C), high capacity and cyclic efficiency are achieved. Needle coke (1900 degrees C) and metallurgical coke (1900 degrees C) in particular give a capacity of over 200 mAh/g and a cyclic efficiency of nearly 100%, whereas poor performance is exhibited by those pretreated at higher or lower temperatures, e.g., petroleum cokes (500 degrees C, 2800 degrees C), pitch coke (500 degrees C) and needle coke (2800 degrees C). The cyclic voltammograms show two electrochemical processes, one at about 0.1 V vs. Li+/Li which is electrochemically reversible, and may be attributed to the intercalation/deintercalation of lithium ions while the other, at about 0.6 V vs. Li+/Li, is electrochemically irreversible and may be assigned to the decomposition of the electrolyte solvent, which leads to formation of the passive film on the anode surface. The experimental results strongly suggest that the pretreatment temperature of cokes and of the solvent are determining factors for the growth, structure and properties of the passive film.

THERMAL BEHAVIORS OF INTRINSIC POLYANILINE AND ITS DERIVATIVES

Thermal properties of polyaniline (PAn), polytoluidine(POT) and polyanisidine(PAs) were examined by TG and DSC techniques. The weight-uptake of POT at 200-300 degrees C was observed and carefully discussed.

THE FRACTURE-BEHAVIOR OF PHENOLPHTHALEIN POLYETHER ETHER KETONE AT ELEVATED-TEMPERATURE FOR LONG TERMS

The fracture behavior of phenolphthalein polyether-ether ketone (PEK-C) affected by physical aging at 200 degrees C was studied by tensile experiments, scanning electron microscopy, and differential scanning calorimetry observations. The ductile-brittle fracture transition (DBT) caused by physical aging can be considered as a competition between fracture mechanisms of crazing and shear yielding. The aging time required for the DBT is found to be around 400 h, based on the morphological studies and tensile experiments. The shear yielding component of the mechanical deformation could erase the aging effect, thus a deaging phenomenon occurs. We found that the deaging phenomenon has an intrinsic relationship with the extent of aging in the specimen and as a result of the fracture behavior. (C) 1995 John Wiley and Sons, Inc.

HELIX-INDUCED ASYMMETRIC POLYMERIZATION

Asymmetric polymerization could be induced by an already formed optically active living prepolymer with one-handed screw sense helix conformation. The usually formed anionic active centre on the prepolymer could be changed to cationic, radical and even of Ziegler-Natta type. These living prepolymers with various kinds of active centre were all effective to induce a consequent asymmetric polymerization of a monomer which may be other than that in the prepolymer, to afford an optically active helical chain with the same screw sense as that of the prepolymer. Eight monomers have been used in the work. Optical rotation, circular dichroism and gelpermeation chromatography have been taken to prove the helix-induced asymmetric polymerization.

STUDIES ON RADIATION EFFECTS OF PTFE .2. RADIATION-INDUCED STRUCTURAL-CHANGES AND THE TEMPERATURE EFFECT

In this work PTFE sheets irradiated with gamma-rays at 150-degrees-C and 200-degrees-C were studied using x-ray photoelectron spectroscopy (XPS). The main structural changes in PTFE due to radiation are the formation of CF3 and CF groups. An irradiation temperature dependence of the relative content of the three kinds of groups in irradiated PTFE was observed. The CF3 groups, especially when irradiation is carried out a lower temperatures, can defluorinate in the same manner as previosly reported for CF2 groups. The CF groups, on the other hand, are observed to increase with increasing irradiation dose and irradiation temperature; the latter was explained as due to an increase in branching structures.

Sedimentation rates and provenance analysis in the Southwestern Okinawa Trough since the mid-Holocene

As a high-sedimentation rate depocenter along the path of the Kuroshio Current, the southwesternmost part of the Okinawa Trough is a key area to understand the Kuroshio history and sediments transportation. A 34.17-m-long sediment core was obtained by the advanced piston corer of Marco Polo/IMAGES XII MARION DUFRESNE during the May 2005 from the Southern Okinawa Trough at site MD05-2908. The recovered sediments were analyzed by AMS C-14 dating, coarse size fraction (> 63 mu m) extraction and moisture content determination in order to study its sedimentation flux and provenance. The depth-age relationship of core MD05-2908 was well constrained by 17 C-14 dating points. The sediments span across the mid-Holocene (6.8 ka B.P.) and have remarkablely high sedimentation rates between 1.8 and 21-2 m/ka, which is well consistent with the modern observations from sediment traps. We identified five 70-200 a periods of abnormally rapid sedimentation events at 6790-6600 a B.P., 5690-5600 a B.P., 4820-4720 a B.P., 1090-880 a B.P., and 260-190 a B.P., during which the highest sedimentation rate is up to 21-2 m/ka. In general, the lithology of the sediments were dominated by silt and clay, associated with less than 5% coarse size fraction (a parts per thousand << 63 mu m). As the most significant sediment source, the Lanyang River in northeastern Taiwan annually deliver about 10Mt materials to the coastal and offshore region of northeast Taiwan, a portion of which could be carried northward by currents toward the study area. Therefore, we concluded that the 5 abnormally rapid sedimentation events may be related to intensified rainfall in Taiwan and thus increased materials to our study area at that time. However, a few extreme-rapid sedimentation events cannot be explained by normal river runoff alone. The large earthquakes or typhoons induced hyperpycnal discharge of fluvial sediment to the ocean may also act as a potential source supply to the Okinawa Trough.

Relative paleointensity of the geomagnetic field during the past 200 ka from the West Philippine Sea and its chronological significance

Our rock magnetic analysis of core Ph05 from the West Philippine Sea demonstrates that the core preserves a strong, stable remanent magnetization and meets the magnetic mineral criteria for relative paleointensity (RPI) analyses. The magnetic minerals in the sequence are dominated by pseudosingle-domain magnetite, and the concentration of magnetic minerals is at the same scale. Both the conventional normalizing method and the pseudo-Thellier method were used in conjunction with the examination of the rock magnetic properties and natural remanent magnetization. Susceptibility (chi), anhysteretic remnant magnetization (ARM) and saturation isothermal remnant magnetization (SIRM) were used as the natural remanent magnetization normalizer. However, coherence analysis indicated that only ARM is more suitable for paleointensity reconstruction. The age model of core is established based on oxygen isotope data and AMS(14)C data, which is consistent with the age model estimated from RPI records. The relative paleointensity data provide a continuous record of the intensity variation during the last 200 ka, which correlates well with the global references RPI stacks. Several prominent low paleointensity values are identified and are correlated to the main RPI minima in the SINT-200 record, suggesting that the sediments have recorded the real changes of geomagnetic field.

The variation of upper ocean structure and paleoproductivity in the Kuroshio source region during the last 200 kyr

A core from the source region of the Kuroshio warm current (east of the Luzon Island) was analyzed using several proxies in order to study the variability of the Western Pacific Warm Pool (WPWP) during the last two glacial-interglacial cycles. Primary productivity (PP) variations were deduced from variations in the coccolith flora. Primary productivity was higher during glacial periods (the end of Marine Isotope Stage [MIS] 3, some periods in MIS 2 and 6), and decreased during interglacial periods (MIS 7, MIS Se and probably MIS 5c-5d), with the lowest PP in MIS 5e. variations in the delta C-13 difference in benthic and bulk carbonate, thus in the vertical gradient of delta C-13 in dissolved inorganic carbon (Delta delta C-13(c). (wuellerstorfi-N. dutertrei) and Delta delta C-13(c.) (wuellerstorfi-coccolith)) Coincided With the PP Changes, showing that export productivity was low during interglacial periods (MIS 7, MIS 5e and Holocene) and high during glacial periods (MIS 6, probably MIS 5c-5d, late MIS 4 and late MIS 3). Comparison of foraminiferal carbonate dissolution indicators and PP changes reveals that nannofossil assemblage in core Ph05-5 is not sensitive to carbonate dissolution intensity. The depth of the thermocline (DOT) was estimated from planktonic forminiferal assemblages, and was relatively greater during interglacial periods (MIS 7, MIS 5e, probably MIS 5c and Holocene) than during glacials (middle MIS 6, probably MIS 5b and 5d, some periods in MIS 4, MIS 3 and MIS 2). Good coherence between the paleoproductivity records and the DOT suggests that the DOT changes could be the primary control factor in changes of paleoproductivity, and the glacial high productivity in the Kuroshio source region could be associated with a global increase of nutrient concentration in the intermediate waters that upwelled into the photic zone. The low CO2 values derived for intervals of high productivity and a relatively shallow DOT suggest that the changes in biological productivity and DOT in the equatorial Pacific could have modified atmospheric CO2 concentrations. High Sea Surface Temperatures (SSTs) during the warm MIS 5e in combination with intensified monsoonal rain fall could have resulted in a more intense stratification of the upper waters, resulting in low nutrient supply to the surface waters and a resulting decrease in productivity. (C) 2010 Elsevier B.V. All rights reserved.

用氟里昴（freon）示踪棉兰老（Mindanao）岛以东海域海洋环流

菲律宾群岛以东的西太平洋赤道和热带海域以存在活跃和复杂的近表面环流而著称。北赤道流（North equatorial current）由东向西不断强化，当到达菲律宾群岛沿岸时，由于受菲律宾群岛的阻挡和β效应，海水在西边界堆积，在西边界形成两支强的西边界流，一支向北形成黑潮（Kuroshio current），一支向南形成棉兰老流（Mindanao current）。这两支西边界流对太平洋的热量重新分配将起着重要的作用。南下的棉兰老流到达棉兰老岛东南海域时，一部分成为印度尼西亚贯穿流（Indonesian throughflow），大部分转向东和苏拉威西海出来的海水及南赤道流（South equatorial current）越过赤道流进入这海域的海水混合，成为北赤道逆流（North equatorial countercurrent）。从1990年10月获得的水文资料算出本航次东边这条断面的纬向地转流断面图，可以看出，1990年晚秋北赤道汉分布在8°N以北的海域，强度最大的流集中在8～9°N之间相对狭窄的地带。而在76号站（3.41°N，128.76°N）到45号站（7.50°N，129.99°N）这条断面上，北赤道逆流分布在3°N～8°N之间，而强度最大流集中在靠近印度尼西亚的摩尔泰岛的南段，另从本航次获得的棉兰老岛以东海域-100米处动力米高度可以看出，在此海域存在两个气旋型涡旋（Cyclonic eddy）一个中心约在10.2°N，128°N，另一个中心在129°N以东，6.5°N左右的地方。用带~(63)Ni电子捕获检测器（ECD）的气相色谱对西太平洋的一些站在0米、50米、100米、150米、200米、300米等六层海水（有些站8～10层）中的氟里昴浓度进行了测定，发现在大部分站位位于300米以上的海水中氟里昴12浓度皆高于1.0 pmol·l~(-1)。表明表层温度混合层和温跃层之间的氟里昴-12交换的比较强烈，特别是靠近棉兰老岛的地方。用水下100米、200米氟里昴-12浓度等值线地域分布和变化，追踪北赤道流，棉兰老流，北赤道流之间的联系，结果与同一海域的动力米高度的地域分布十分吻合。再通过比较本航次东边这条断面的氟里昴-12浓度断面图和地转流断面图，我们能清楚地看的到，西向流区对应着高浓度的氟里昴-12分布，特别是在8～9°N流轴上面存在着氟里昴-12浓度最大值轴，而东向流区对应着相对低浓度的氟里昴-12分布，由以上结果，我们可以得出结论：用氟里昴示踪棉兰老岛以东海域的近表面环流是十分有效的，这样，氟里昴浓度在这海域的分布对今后建立本海域的大洋环流数学模式将能起重要作用。本文根据氟里昴主要来源是北半球的工业区，提出了一个氟里昴输入棉兰老岛以东海域的机制。

基于黑板结构的多传感器数据溶合系统FS-1

本文借助于数据溶合方法中的引导法构成的系统在移动式机器人定位中取得了令人满意的结果.本系统的特点是:用分布式黑板作为计算机构,使系统具有并行处理能力;把时间(时序)推理引入系统.在数据溶合中考虑了时间的重要作用.本文提出的溶合方法和结构原则上可用于其它相关的问题领域.

200 ℃水热条件下金属铂的氢渗透常数测定

本文采用氢感应法,测定低温水热条件下Pt 的H2 渗透常数k ,并可根据H2 渗透来计算实验体系的氧逸 度。这种方法无需依赖H2 在氧缓冲体系与实验体系间平衡状态的到达, 但要求有精确的氢渗透常数。本研 究在200 ℃, NNO 及HM氧缓冲的实验条件下,通过测定氢感应体系中淬火溶液Cl - 浓度的变化, 计算求得Pt 的H2 渗透常数k 为10 - 13～10 - 14数量级。并讨论了在实验及数据处理过程中对H2 渗透常数k 可能带来的误 差及影响因素。

Peak identification for PCDD/Fs in environmental samples at different temperature programs

A method has been developed for peak recognition of 136 polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) at different temperature programs. Their retention behaviours are predicted on the basis of an identification database of retention values (A, B) of gas chromatography. By the retention times of C-13 labelled 2,3,7,8-substituted PCDD/F internal standards, the retentions of all PCDDs and PCDFs can be calculated. After comparison with the retentions of practical environmental samples, the predicted values have been proved to be very accurate. (C) 2000 Elsevier Science Ltd. All rights reserved.