Arabinogalactan as a carrier for contrast agent in magnetic resonance imaging

Arabinogalactan-Gd-DTPA was synthesized by the reaction of diethylenetriaminepenta-acetic acid (DTPA) bisanhydride with polysaccharide in dry DMSO and characterized by FTIR, elemental analysis and ICP-AES. Its stability was investigated by competition with Ca2+, EDTA, DTPA. The t(1)-relaxivity is 8.06 mmol(-1) . L . s(-1) in D2O, 8.48 mmol(-1) . L . s(-1) in 0.725 mmol . L-1 BSA, respectively. t(1)-weighted MR imaging of rat kidney and liver showed a remarkable enhancement post injection of Arabinogalactan-Gd-DTPA. The results indicate that the arabinogalactan-Gd-DTPA is a potential contrast agent for MRI.

An evaluation of gadolinium polyoxornetalates as possible MRI contrast agent

Two gadolinium polyoxometalates, K9GdW10O36 and K-11 [Gd(PW11O39)(2)], have been evaluated both in vivo and in vitro as candidates for tissue-specific MRI contrast agents. T-1-relaxivities of 6.89 mM(-1) . s(-1) for K9GdW10O36 and 5.27 mM(-1) . s(-1) for K-11[Gd(PW11O39)(2)] are slightly higher than that of the commercial MRI contrast agent (Gd-DTPA). Both compounds bind with bovine serum albumin and human serum transferrin and favorable liver-specific contrast enhancement in in vivo MRI with Sprague-Dawley rats after i.v. administration has been demonstrated. Imaging studies demonstrate that the two agents have a long residence time, showing MR signal enhancement in the liver for more than 40 min, longer than commercially available contrast agents. In vivo and in vitro assays showed that GdW10 and Gd(PW11)(2) are promising liver-specific MRI contrast agents and GdW10 may be used in the diagnosis of the pathological state. However, with the higher acute toxicity, the two gadolinium polyoxometalates need to be modified and studied further before clinical use.

Study of facilitated potassium ion transfer across a water vertical bar 1,2-dichloroethane interface using different phase volume ratio systems

A study of potassium ion transfer across a water \ 1,2-dichloroethane (W \ DCE) interface facilitated by dibenzo-18-crown-6 (DB18C6) with various phase volume ratio systems is presented. The key point was that a droplet of aqueous solution containing a redox couple, Fe(CN)(6)(3-)/Fe(CN)(6)(4-), with equal molar ratio, was first attached to a platinum electrode surface, and the resulting droplet electrode was then immersed into the organic solution containing a hydrophobic electrolyte to construct a platinum electrode/aqueous phase/organic phase system. The interfacial potential of the W \ DCE within the series could be externally controlled because the specific compositions in the aqueous droplet make the Pt electrode function like a reference electrode as long as the concentration ratio of Fe(CN)(6)(3-)/Fe(CN)(6)(4-) remains constant. In this way, a conventional three-electrode potentiostat can be used to study the ion transfer process at a liquid \ liquid (L \ L) interface facilitated by an ionophore with variable phase volume ratio (r = V-o/V-w). The effect of r on ion transfer and facilitated ion transfer was studied in detail experimentally. We also demonstrated that as low as 5 x 10(-8) M DB18C6 could be determined using this method due to the effect of the high phase volume ratio.

Charge transport in a blue-emitting alternating block copolymer with a small spacer to conjugated segment length ratio

We analyze current versus voltage data obtained using single carrier injection in several metal/polymer/metal sandwich structures. The polymer used in each case is a soluble blue-emitting alternating block copolymer. Our experimental results demonstrate that the electron transport is space-charge limited by the high density of traps having an exponential energy distribution (temperature dependent characteristic energy) in the copolymer. The electron mobility of 8x10(-10) cm(2)/V s is directly determined using space-charge-limited current analytical expressions. Hole transport is also space-charge limited, with a mobility of 2x10(-6) cm(2)/V s. A hole trap with energy 0.17 eV is observed. We compare these results with those obtained for related block copolymers with different spacer and conjugated segment lengths and discuss the influence of spacer length and conjugated segment length on the charge transport properties. (C) 2000 American Institute of Physics. [S0021-8979(00)04501-1].

Studies on structure-property relationship between color reagents and contrast of their color reactions with cerium by topological indices

In this paper, three topological indices A(m1), A(m2) and A(m3) have been applied to multivariate analysis in structure property relationship studies. The topological indices oi fourty-three asymmetrical phosphono bisazo derivatives of chromotropic acid have been calculated, The structure-property relationship between color reagents and contrast of color reactions with cerium has been studied by A, indices and structure selective factors, Good results have been obtained.

Gonad development characteristics and sex ratio in triploid chinese shrimp (Fenneropenaeus chinensis)

This paper details for the first time the gonad development characteristics and sex ratio of triploid shrimp (Fenneropenaeus chinensis). In triploid shrimp the development of gonad is apparently impaired, especially in females. In the ovary of triploids, germ cells mainly remain at oogonia stage during September through December. From January to February of the next year, partial primary oocytes developed in the ovary lobes. Spermatocytes and spermatids could be observed in the testes of triploids, and a few sperm were observed in the vas deferens and spermatophores. The morphology of sperms in triploid shrimp was abnormal. Flow cytometry was used to detect the ploidy of sperm in the vas deferens. The data showed that triploidy could affect the sex ratio in Chinese shrimp. The female-to-male ratio in triploids of about 4:1 will favor triploid shrimp aquaculture.

长江口上升流区营养盐动力学

近年来，东中国海赤潮灾情严重，且74.7%的赤潮集中在 30°30′～32°00′N、122°15′～123°10′E的“赤潮高发区”。在研究该区赤潮成因时，长江口沿岸上升流的影响越来越受到人们的关注，并被一些专家观测和研究。但目前为止，针对该区营养盐动力学特征及其对叶绿素a影响的研究较少，且不系统。 本文根据2004年四个季度月的调查资料，系统地探讨了长江口上升流区营养盐动力学特征；估算了上升流的营养盐通量，并和陆源输入通量进行了比较。初步探讨了上升流对该区营养盐结构和浮游植物生长的影响。为深入研究长江口富营养化和赤潮形成机制提供了参考。 结果表明春季在122°20′～123°00′E，31°00′～32°00′N以北海域存在低温、高盐、低溶解氧的沿岸上升流。它不但可把底层高含量磷酸盐输送到10m层以上海区，而且还为上层海区输入了相对低含量硝酸盐和硅酸盐，从而改善了上层营养盐结构，使得营养盐比值接近Redfield Ratios，同时还改善了上层的透明度；从而有利于浮游植物的繁殖。夏季上升流受到强大的长江冲淡水压制，表现不如春季明显，主体水团出现在122°20′～123°00′E，31°15′～31°50′N海区10m层以下。 在秋、冬季，上升流现象被更强的对流现象所掩盖，表现为台湾暖流表层水的入侵。表、底层水域不仅温、盐度分布十分接近，而且营养盐结构差异也较小。冬季台湾暖流水中的磷酸盐含量远比秋季高，与春、夏季上升流水团中磷酸盐含量接近。硝酸盐和硅酸盐含量比秋季稍高，比春、夏季上升流水团中的含量稍低。 叶绿素a季节性分布表明，在春、夏季的10m层以下水域，叶绿素a受到透明度限制，含量相差不大；而在表层和10m层之间，春季叶绿素a的含量远高于夏季，说明春季的营养盐结构和自然条件更有利于浮游植物的繁荣生长。在秋季台湾暖流水影响的区域，表层叶绿素a含量较夏季稍低。而冬季该区叶绿素a含量则是最低的。 对长江口上升流水团春季营养盐通量的计算结果表明，上升流水团中磷酸盐输送通量远远高于长江径流输入，是其径流通量的两倍以上，可能会成为影响该海区磷酸盐分布以及浮游植物生长的一个值得关注的因素。 关键词：上升流，营养盐动力学，营养盐结构，叶绿素a，长江冲淡水

Nutrient characteristics in the Yangtze River Estuary and the adjacent East China Sea before and after impoundment of the Three Gorges Dam

From November 2002 to 2006, five cruises were undertaken in the Yangtze River Estuary and the adjacent East China Sea to compare the nutrient concentrations, ratios and potential nutrient limitation of phytoplankton growth before and after impoundment (June 2003) of the Three Gorges Dam (TGD). Concentrations of dissolved inorganic nitrogen (DIN), soluble reactive phosphorus (SRP) and total nitrogen (TN) exhibited an increasing trend from 2002 to 2006. In contrast, total phosphorus (TP) concentration exhibited a decreasing trend. The mean concentrations of DIN, SRP, and TN in the total study area increased from 21.4 mu M, 0.9 mu M, and 41.8 mu M in 2002 to 37.5 mu M, 1.3 mu M. and 82.2 mu M in 2006, respectively. while TP decreased from 2.1 mu M to 1.7 mu M. The concentration of dissolved reactive silica (DRSi) had no major fluctuations and the differences were not significant. The mean concentration of DRSi in the total study area ranged from 52.5 to 92.3 mu M. The Si:N ratio decreased significantly from 2.7 in 2002 to 1.3 in 2006, while TN: TP ratio increased from 22.1 to 80.3. The area of potential P limitation of phytoplankton growth expanded after 2003 and potential Si limitation appeared in 2005 and 2006. Potential P limitation mainly occurred in an area of salinity less than 30 after 2003, while potential Si limitation occurred where the salinity was greater than 30. By comparison with historical data, the concentrations of nitrate and SRP in this upper estuary during November 1980-2006 increased obviously after impoundment of TGD but DRSi decreased. Meanwhile, the ratios of N:P, Si:N and Si:P decreased obviously. (c) 2009 Elsevier B.V. All rights reserved.

A field study on the conversion ratio of phytoplankton biomass carbon to chlorophyll-a in Jiaozhou Bay, China

A one-year field study was conducted to determine the conversion ratio of phytoplankton biomass carbon (Phyto-C) to chlorophyll-a (Chl-a) in Jiaozhou Bay, China. We measured suspended particulate organic carbon (POC) and phytoplankton Chl-a samples collected in surface water monthly from March 2005 to February 2006. The temporal and spatial variations of Chl-a and POC concentrations were observed in the bay. Based on the field measurements, a linear regression model II was used to generate the conversion ratio of Phyto-C to Chl-a. In most cases, a good linear correlation was found between the observed POC and Chl-a concentrations, and the calculated conversion ratios ranged from 26 to 250 with a mean value of 56 A mu g A mu g(-1). The conversion ratio in the fall was higher than that in the winter and spring months, and had the lowest values in the summer. The ratios also exhibited spatial variations, generally with low values in the near shore regions and relatively high values in offshore waters. Our study suggests that temperature was likely to be the main factor influencing the observed seasonal variations of conversion ratios while nutrient supply and light penetration played important roles in controlling the spatial variations.

Studies on growth rate and grazing mortality rate by microzooplankton of size-fractionated phytoplankton in spring and summer in the Jiaozhou Bay, China

Dilution experiments were performed to examine the growth rate and grazing mortality rate of size-fractionated phytoplankton at three typical stations, inside and outside the bay, in the spring and summer of 2003 in the Jiaozhou Bay, China. in spring, the phytoplankton community structure was similar among the three stations, and was mainly composed of nanophytoplankton, such as, Skeletonema costatum and Cylindrotheca closterium. The structure became significantly different for the three stations in summer, when the dominant species at Stas A, B and C were Chaetoceros curvisetus, Pseudo-nitzschia delicatissima, C. affinis, C. debilis, Coscinodiscus oculus-iridis and Paralia sulcata respectively. Tintinnopsis beroidea and T. tsingtaoensis were the dominant species in spring, whereas the microzooplankton was apparently dominated by Strombidium sp. in summer. Pico- and nanophytoplankton had a relatively greater growth rate than microzooplankton both in spring and summer. The growth rate and grazing mortality rate were 0.18 similar to 0.44 and 0.12 similar to 1.47 d(-1) for the total phytoplankton and 0.20 similar to 0.55 and 0.21 similar to 0.37 d-1 for nanophytoplankton in spring respectively. In summer, the growth rate and grazing mortality rate were 0.38 similar to 0.71 and 0.27 similar to 0.60 d-1 for the total phytoplankton and 0.11 similar to 1.18 and 0.41 similar to 0.72 d(-1) for nano- and microphytoplankton respectively. The carbon flux consumed by microzooplankton per day was 7.68 similar to 39.81 mg/m(3) in spring and 12.03 similar to 138.22 mg/m(3) in summer respectively. Microzooplankton ingested 17.56%similar to 92.19% of the phytoplankton standing stocks and 31.77%similar to 467.88% of the potential primary productivity in spring; in contrast, they ingested 34.60%similar to 83.04% of the phytoplankton standing stocks and 71.28%similar to 98.80% of the potential primary productivity in summer. Pico- and nanophytoplankton appeared to have relatively greater rates of growth and grazing mortality than microphytoplankton during the experimental period. The grazing rate of microzooplankton in summer was a little bit greater than that in spring because of the relatively higher incubation temperature and different dominant microzooplankton species. Microzooplankton preferred ingesting nanophytoplankton to microphytoplankton in spring, while they preferred ingesting picophytoplankton to nanophytoplankton and microphytoplankton in summer. Compared with the results of dilution experiments performed in various waters worldwide, the results are in the middle range.

地质导向钻井关键技术及方法

On the basis of analyzing the principle and realization of geo-steering drilling system, the key technologies and methods in it are systematically studied in this paper. In order to recognize lithology, distinguish stratum and track reservoirs, the techniques of MWD and data process about natural gamma, resistivity, inductive density and porosity are researched. The methods for pre-processing and standardizing MWD data and for converting geological data in directional and horizontal drilling are discussed, consequently the methods of data conversion between MD and TVD and those of formation description and adjacent well contrast are proposed. Researching the method of identifying sub-layer yields the techniques of single well explanation, multi-well evaluation and oil reservoir description. Using the extremum and variance clustering analysis realizes logging phase analysis and stratum subdivision and explanation, which provides a theoretical method and lays a technical basis for tracing oil reservoirs and achieving geo-steering drilling. Researching the technique for exploring the reservoir top with a holdup section provides a planning method of wellpath control scheme to trace oil and gas reservoir dynamically, which solves the problem of how to control well trajectory on condition that the layer’s TVD is uncertain. The control scheme and planning method of well path for meeting the demands of target hitting, soft landing and continuous steering respectively provide the technological guarantee to land safely and drill successfully for horizontal, extended-reach and multi-target wells. The integrative design and control technologies are researched based on geology, reservoir and drilling considering reservoir disclosing ratio as a primary index, and the methods for planning and control optimum wellpath under multi-target restriction, thus which lets the target wellpath lie the favorite position in oil reservoir during the process of geo-steering drilling. The BHA (bottomhole assembly) mechanical model is discussed using the finite element method, and the BHA design methods are given on the basis of mechanical analyses according to the shape of well trajectory and the characteristics of BHA’s structure and deformation. The methods for predicting the deflection rate of bent housing motors and designing their assemblies are proposed based on the principle of minimum potential energy, which can clearly show the relation between the BHA’s structure parameters and deflection rate, especially the key factors’ effect to the deflection rate. Moreover, the interaction model between bit and formation is discussed through the process of equivalent formation and equivalent bit considering the formation anisotropy and bit anisotropy on the basis of analyzing the influence factors of well trajectory. Accordingly, the inherence relationship among well trajectory, formation, bit and drilling direction is revealed, which lays the theory basis and technique for predicting and controlling well trajectory.

三门峡宋家店黄土－古土壤序列的地层学研究及其古环境记录

The Sanmen Gorge area is located in the southernmost margin of the Chinese Loess Plateau with well developed eolian deposit sequence for the past 2.6 Ma, providing a key site for further understanding of the evolution history of the East Asian monsoon since late Pliocene. This study attempted to characterize the stratigraphy and paleoclimate record of the loess-paleosol sequence in the Songjiadian section. The work involved includes systematic field investigation, paleomagnetic and rock magnetic analyses, grain size and major chemical composition analyses, and multiple proxy measurements of magnetic susceptibility, color reflectance and the ratio of CBD-dissolvable iron to the total iron (FeD/FeT). By comparisons of the Songjiadian section with well studied loess sections in the west of the Sanmen Gorge, the spatial variations of the East Asian monsoon was evaluated for some periods during which typical loess or paleosols developed. The following conclusions have been obtained. 1. Stratigraphic correlation and paleomagnetic result demonstrate that the loess-paleosol sequence in the Songjiadian section was accumulated from 2.6Ma, and is generally a complete and continuous loess sequence. However, notable differences from type loess sections have been identified for a few loess and paleosol units, featured by absence or anomalous thickness in the Songjiadian section. 2. Magnetic susceptibility and chromaticity records clearly reveal the loess-paleosol cycles, and indicate that the Sanmen Gorge area has been warmer and more humid than the Lingtai and Jingchuan sections in the western central Loess Plateau since the Early Pleistocene. 3. Grain size distribution patterns are typical of eolian dust, and show a great similarity between various units of loess and paleosols, and between the S32 and the underlying Red Clay through the Songjiadian profile, suggesting the eolian origin for the loess, paleosols and the Red Clay. 4. Comparison of the FeD/FeT curves from different loess sections indicates a stronger chemical weathering in the Songjiadian section and notable enhancement around 1800, 800 and 600 ka BP, implying the strengthening of the East Asian monsoon during these periods. In contrast, it was weakened at 1100 ka BP. Generally, the summer monsoon shows a gradually decreasing trend during the entire Pleostocene, but the spatial pattern typified by an increasing trend in weathering intensity from north to south remained the same. 5. The loess unit L9 in the Songjiadian section displays two geomagnetic field anomalies with the midpoint ages of 0.917 and 0.875 Ma respectively, with a segment of 12 ka. They are demonstrated to be equivalent to the Santa Rosa and Kamikatsura geomagnetic excursions. 6. Magnetite is the main magnetic carrier for both loess and paleosols. Maghemite concentration is higher in paleosols than in loess, and is an important carrier for the enhanced magnetic susceptibility in paleosols. Magnetic fabric analysis suggests a dominant N-S wind direction prevailing in the L9 and L15, while the summer winds were dominantly in NNE-SSW direction during the S8 period, notably differing from previous studies.

中国北方中新世风尘物质来源及古气候的地球化学指示

The most prominent tectonic and environmental events during the Cenozoic in Asia are the uplift of the Himalaya-Tibetan plateau, aridification in the Asian interior, and onset of the Asian monsoons. These caused more humid conditions in southeastern China and the formation of inland deserts in northwestern China. The 22 Ma eolian deposits in northern China provide an excellent terrestrial record relative to the above environmental events. Up to date, many studies have focused on the geochemical characters of the late Mio-Pleistocene eolian deposits, however, the geochemical characteristics of the Miocene loess and soils is still much less known. In this study, the elemental and Sr-Nd isotopic compositions of the eolian deposits from the Qinan (from 22.0 to 6.2 Ma) and the Xifeng (from 3.5 Ma until now) loess-soil sections were analyzed to examine the grain size effects on the element concentrations and the implications about the dust origin and climate. The main results are as follows: 1. The contents of Si, Na, Zr and Sr are higher in the coarser fractions while Ti and Nb have the highest contents in the 2-8 μm fractions. Al, Fe, Mg, K, Mn, Rb, Cu, Ga, Zn, V, Cr, Ni, LOI have clear relationships with grain-size, more abundant in the fine fraction while non significant relationship is observed for Y. Based on these features, we suggest that K2O/Al2O3 ratio can be used to address the dust provenance, and that VR (Vogt ratio = (Al2O3+K2O)/(MgO+CaO+Na2O)) can be used as a chemical weathering proxy for the Miocene eolian deposits because of their relative independence on the grain size. Meanwhile, SiO2/Al2O3 molar ratio is a best geochemical indicator of original eolian grain size, as suggested in earlier studies. 2. Analyses on the Sr and Nd isotope composition of the last glacial loess samples (L1) and comparison with the data from the deserts in northern China suggest that that Taklimakan desert is unlikely to be the main source region of the eolian dust. In contrast, these data suggest greater contributions of the Tengger, Badain Jaran and Qaidam deserts to the eolian dust during the last glacial cycle. Since the geochemical compositions (major, trace, REE and Sr, Nd isotope) of loess samples for the past 22 Ma are broadly similar with the samples from L1, these data trend to suggest relatively stable and insignificant changes of dust sources over the past 22 Ma. 3. Chemical weathering is stronger for Miocene paleosol samples than for the Plio-Pleistocene ones, showing warmer/more humid climatic conditions with a stronger summer monsoon in the Miocene. However, chemical weathering is typical of Ca-Na removal stage, suggesting a climate range from semiarid to subhumid conditions. These support the notion about the formation of a semi-arid to semi-humid monsoonal regime by the early Miocene, as is consistent with earlier studies.