STRUCTURE AND PROPERTIES OF MALEATED HIGH-DENSITY POLYETHYLENE

Possible changes in the structure and properties of maleated polyethylene (HDPE-MA) at different degrees of grafting (D.G.) were examined. At the level of 1.6 maleic anhydride (MA)/100 ethylene units E, 70-80% of crystallinity of the parent PE was retaine

ELECTROCHEMICAL SCANNING-TUNNELING-MICROSCOPY

An ECSTM apparatus with an ideal tip using a homemade SSX-1A STM instrument has been constructed. STM and ECSTM tips were made by electrochemical etching and insulating with paraffin, silicon rubber or epoxy resin under an optical microscope. In situ imag

PC/ABS BLENDS:COMPATIBILIZATION AND MECHANICAL-BEHAVIOR

PC/ABS(M) blends, encompassing the whole composition range between pure PC and ABS(M), were prepared by melt-mixing in a Brabender-like apparatus. Thermal, mechanical and impact tests were performed on compression moulded specimens. Inward Tg shifts were

MICROSTRUCTURE ANALYSIS OF 3 SEGMENTED COPOLYMERS CONTAINING POLYDIMETHYLSILOXANE BY SOLID-STATE HIGH-RESOLUTION NMR

The microstructure of two bicomponent and one tricomponent segmented copolymers, based on polydimethylsiloxane, poly(p-hydroxystyrene) or/and polysulfone, were investigated using an extended Goldman-Shen pulse sequence, proton spin-spin relaxation measurements, and C-13 and Si-29 NMR spectra. The results indicate that there exist four phases with different sizes, components and morphological structure in the segmented copolymers studied in this work, i. e., a rigid-chain phase of very slow motion, a rigid-chain-rich phase of slow motion, a flexible-chain-rich phase of fast motion and a flexible-chain phase of faster motion. The sizes of different domains, calculated from the spin diffusion rates, are about 50-100 angstrom for the flexible-chain-rich phase of fast motion and 200-300 angstrom for the flexible-chain phase of faster motion. The relative quantities of polydimethylsiloxane in the flexible-chain phase of fast motion are slightly different in different kinds of segmented copolymers.

MISCIBILITY AND PHASE-BEHAVIOR IN BLENDS OF POLY(HYDROXYETHER OF BISPHENOL-A) WITH POLY(ETHYLENE OXIDE-CO-PROPYLENE OXIDE)

The miscibility of poly(hydroxyether of bisphenol A) (phenoxy) with a series of poly(ethylene oxide-co-propylene oxide) (EPO) has been studied. It was found that the critical copolymer composition for achieving miscibility with phenoxy around 60-degrees-C is about 22 mol % ethylene oxide (EO). Some blends undergo phase separation at elevated temperatures, but there is no maximum in the miscibility window. The mean-field approach has been used to describe this homopolymer/copolymer system. From the miscibility maps and the melting-point depression of the crystallizable component in the blends, the binary interaction energy densities, B(ij), have been calculated for all three pairs. The miscibility of phenoxy with EPO is considered to be caused mainly by the intermolecular hydrogen-bonding interactions between the hydroxyl groups of phenoxy and the ether oxygens of the EO units in the copolymers, while the intramolecular repulsion between EO and propylene oxide units in the copolymers contributes relatively little to the miscibility.

热带西太平洋边缘晚第四纪以来的古环境研究

利用取自热带太平洋边缘的5个柱状岩芯Ph05-5、WP3、MD2908、Z14-6和WP7，通过对其微体古生物和生物地球化学成分的分析，结合浮游有孔虫氧、碳同位素数据、AMS14C测年结果和已有的研究资料，分别研究了热带西太平洋边缘晚第四纪以来的钙质超微化石群落特征、碳酸盐旋回、超微化石氧碳同位素特征、古生产力和上层海水结构演化以及高分辨率东亚夏季风指标，并探讨了碳酸盐旋回、古生产力和上层海水结构演化、全新世东亚夏季风强弱变化的控制机制，以及钙质超微化石下透光带属种Florisphaera profunda的相对百分含量变化在热带太平洋边缘的古环境指示意义及不同环境条件下的控制机制。 西菲律宾海Ph05-5岩芯和台湾东南部WP3岩芯中CaCO3和钙质超微化石碳酸盐溶解指数、初级生产力指标的变化显示约190 kyr BP以来CaCO3含量整体上都表现为冰期高、间冰期低的“太平洋型”旋回特征，但菲律宾以东海区在末次冰期（MIS 4~2期）内部又显示出间冰段含量高、冰段含量低的“大西洋型”旋回特征。碳酸盐旋回的主要控制因素在菲律宾以东海区是碳酸盐溶解作用，而台湾东南海区则是初级生产力变化引起的钙质生物输入量的波动。 西菲律宾海Ph05-5岩芯中190 kyr BP以来的钙质超微化石δ18O值在末次间冰期（MIS 5e）和全新世明显低于末次冰期（MIS 5d~2）和倒数第二次冰期（MIS 6）。超微化石δ18O值与浮游和底栖有孔虫δ18O值都呈明显的正相关关系，但是超微化石的δ18O平均值重于表层浮游有孔虫Globigeriniodes rubber，轻于中层Neogloboquadrina dutertrei。超微化石δ13C值变化与其绝对丰度变化表明西菲律宾海区大约在MIS 6和MIS 5e期，表层海水初级生产力相当稳定且显著低于其它各时期；约从MIS 5d期开始表层初级生产力显著上升，并一直持续到末次冰期；在MIS1、2期，表层初级生产力有所下降，但仍高于MIS 6和MIS 5e期。 Ph05-5岩芯中钙质超微化石下透光带属种F. profunda相对百分含量和浮游有孔虫转换函数的温跃层深度变化表明西太平洋暖池北缘约190 kyr BP 以来，营养跃层和温跃层冰期（MIS 6期和5d~2期）浅，间冰期（MIS5e）和全新世深，MIS5e期是最近两个冰期旋回中营养跃层和温跃层深度最深的时期。F. profunda百分含量初级生产力转换方程计算结果和与钙质超微化石绝对丰度的变化显示冰期初级生产力高，间冰期和全新世初级生产力低， MIS5e期初级生产力最低。此外，Δδ13C C. wullerstorf-coccolith和Δδ13C C. wullerstorf-N. dutertrei差值的变化也说明190 kyr BP以来冰期表层输出生产力高于间冰期，其中最为突出的特征也是MIS5e期为生产力输出的最低值期。上层海水结构和生产力的上述变化特征与现代La Niňa事件爆发时的海洋环境相当类似，该海区MIS5e期可能是La Niňa事件频繁爆发的一段时期，可以与现代La Niňa现象类比。同时，根据Wyrtki提出的信风张弛理论推测MIS5e期，由于La Niňa事件的频繁爆发黑潮主流应该是增强的。 热带西太平洋暖池核心区WP7岩芯中250 kyr BP以来的初级生产力在间冰期明显低于冰期，间冰期生产力相对稳定，冰期(MIS6，4和2)生产力升降幅度较大；冰期向间冰期过渡的冰消期内生产力的降低是相对缓慢的，而间冰期向冰期过渡时生产力的增加是迅速的。初级生产力指标的交叉频谱分析显示出偏心率、斜率、岁差（半岁差）、30kyr和50kyr周期。说明暖池区晚第四纪以来古生产力变动除了受全球冰量变动控制以外，低纬区的岁差驱动也是主要控制因子。约250 kyr BP以来古生产力的变化与Vostok冰心的CO2记录在30kyr周期上高度相关，低CO2值与高生产力相对应，印证了大洋初级生产力在全球碳循环中扮演了重要的“吸收者”的角色，30kyr周期是赤道太平洋地区生物生产力ENSO式变化特征的体现，这也证明了低纬地区生物泵在控制大气CO2浓度方面的重要作用。另外，在岁差周期段，底栖有孔虫U+B含量和N. dutertrei δ13C代表的生产力变动领先于有孔虫δ18O代表的冰体积变化约2.6~7kyr（0.5kyr,2.6 kyr,4.2 kyr, 7kyr），表明在千年时间尺度上日射是该区生产力变化的直接驱动力，两极冰体积变化（δ18O）没有明显的影响低纬气候波动。 对热带西太平洋边缘海区WP7、Ph05-5、WP3和Z14-6四个岩芯中晚第四纪以来超微化石下透光带属种F. profunda相对百分含量变化进行横向对比研究表明，F. profunda百分含量分布并非简单受水深控制，而是由海水上层复杂的生态因素所决定；F. profunda相对百分含量变化曲线与浮游有孔虫N. dutertrei氧同位素曲线呈不同程度的相关性，N. dutertrei 氧同位素越轻，对应的F. profunda相对百分含量越高；冲绳海槽中部的Z14-6岩芯中F. profunda相对含量变化的主控因子是黑潮流的强弱变化；WP7和Ph05-5两个岩芯中F. profunda相对含量变化与低纬地区暖池变化特征密切相关。 6800 yr BP以来台湾东北部MD2908岩芯中F. profunda相对百分含量变化与太阳黑子数量呈明显的反相关关系，而且3700 yrBP以来更为明显。由于F. profunda相对百分含量变化与该地区东亚夏季风引起的降雨量密切相关，所以推测6800 yr BP以来东亚夏季风受太阳活动影响，其中的纽带是IZCT的纬向位置变动。

两种超微细矿物粉体材料的制备及应用研究

Superfine mineral materials are mainly resulted from the pulverization of natural mineral resources, and are a type of new materials that can replace traditional materials and enjoy the most extensive application and the highest degree of consumption in the present day market. As a result, superfine mineral materials have a very broad and promising prospect in terms of market potential. Superfine pulverization technology is the only way for the in-depth processing of most of the traditional materials, and is also one of the major means for which mineral materials can realize their application. China is rich in natural resources such as heavy calcite, kaolin, wollastonite, etc., which enjoy a very wide market of application in paper making, rubber, plastics, painting, coating, medicine, environment-friendly recycle paper and fine chemical industries, for example. However, because the processing of these resources is generally at the low level, economic benefit and scale for the processing of these resources have not been realized to their full potential even up to now. Big difference in product indices and superfine processing equipment and technologies between China and advanced western countries still exists. Based on resource assessment and market potential analysis, an in-depth study was carried out in this paper about the superfine pulverization technology and superfine pulverized mineral materials from the point of mineralogical features, determination of processing technologies, analytical methods and applications, by utilizing a variety of modern analytical methods in mineralogy, superfine pulverization technology, macromolecular chemistry, material science and physical chemistry together with computer technology and so on. The focus was placed on the innovative study about the in-depth processing technology and the processing apparatus for kaolin and heavy calcite as well as the application of superfine products. The main contents and the major achievements of this study are listed as follows: 1. Superfine pulverization processing of mineral materials shall be integrated with the study of their crystal structures and chemical composition. And special attention shall be put on the post-processing technologies, rather than on the indices for particle size, of these materials, based on their fields of application. Both technical feasibility and economic feasibility shall be taken into account for the study about superfine pulverization technologies, since these two kinds of feasibilities serve as the premise for the industrialized application of superfine pulverized mineral materials. Based on this principle, preposed chemical treatment method, technology of synchronized superfine pulverization and gradation, processing technology and apparatus of integrated modification and depolymerization were utilized in this study, and narrow distribution in terms of particle size, good dispersibility, good application effects, low consumption as well as high effectiveness of superfine products were achieved in this study. Heavy calcite and kaolin are two kinds of superfine mineral materials that enjoy the highest consumption in the industry. Heavy calcite is mainly applied in paper making, coating and plastics industries, the hard kaolin in northern China is mainly used in macromolecular materials and chemical industries, while the soft kaolin in southern China is mainly used for paper making. On the other hand, superfine pulverized heavy calcite and kaolin can both be used as the functional additives to cement, a kind of material that enjoys the biggest consumption in the world. A variety of analytical methods and instruments such as transmission and scanning electron microscopy, X-ray diffraction analysis, infrared analysis, laser particle size analysis and so on were applied for the elucidation of the properties and the mechanisms for the functions of superfine mineral materials as used in plastics and high-performance cement. Detection of superfine mineral materials is closely related to the post-processing and application of these materials. Traditional detection and analytical methods for superfine mineral materials include optical microscopy, infrared spectral analysis and a series of microbeam techniques such as transmission and scanning electron microscopy, X-ray diffraction analysis, and so on. In addition to these traditional methods, super-weak luminescent photon detection technology of high precision, high sensitivity and high signal to noise ratio was also utilized by the author for the first time in the study of superfine mineral materials, in an attempt to explore a completely new method and means for the study of the characterization of superfine materials. The experimental results are really exciting! The innovation of this study is represented in the following aspects: 1. In this study, preposed chemical treatment method, technology of synchronized superfine pulverization and gradation, processing technology and apparatus of integrated modification and depolymerization were utilized in an innovative way, and narrow distribution in terms of particle size, good dispersibility, good application effects, low consumption as well as high effectiveness of superfine products were achieved in the industrialized production process*. Moreover, a new modification technology and related directions for producing the chemicals were invented, and the modification technology was even awarded a patent. 2. The detection technology of super-weak luminescent photon of high precision, high sensitivity and high signal to noise ratio was utilized for the first time in this study to explore the superfine mineral materials, and the experimental results can be compared with those acquired with scanning electron microscopy and has demonstrated its unique advantages. It can be expected that further study may possibly help to result in a completely new method and means for the characterization of superfine materials. 3. During the heating of kaolinite and its decomposition into pianlinite, the diffraction peaks disappear gradually. First comes the disappearance of the reflection of the basal plane (001), and then comes the slow disappearance of the (hkl) diffraction peaks. And this was first discovered during the experiments by the author, and it has never before reported by other scholars. 4. The first discovery of the functions that superfine mineral materials can be used as dispersants in plastics, and the first discovery of the comprehensive functions that superfine mineral materials can also be used as activators, water-reducing agents and aggregates in high-performance cement were made in this study, together with a detailed discussion. This study was jointly supported by two key grants from Guangdong Province for Scientific and Technological Research in the 10th Five-year Plan Period (1,200,000 yuan for Preparation technology, apparatus and post-processing research by using sub-micron superfine pulverization machinery method, and 300,000 yuan for Method and instruments for biological photon technology in the characterization of nanometer materials), and two grants from Guangdong Province for 100 projects for scientific and technological innovation (700,000 yuan for Pilot experimentation of superfine and modified heavy calcite used in paper-making, rubber and plastics industry, and 400,000 yuan for Study of superfine, modified wollastonite of large length-to-diameter ratio).

Modification of a poly(methyl methacrylate) injection-molded microchip and its use for high performance analysis of DNA

Inexpensive and permanently modified poly(methyl methacrylate)(PMMA) microchips were fabricated by an injection-molding process. A novel sealing method for plastic microchips at room temperature was introduced. Run-to-run and chip-to-chip reproducibility was good, with relative standard deviation values between 1-3% for the run-to-run and less than 2.1% for the chip-to-chip comparisons. Acrylonitrile-butadiene-styrene (ABS) was used as an additive in PMMA substrates. The proportions of PMMA and ABS were optimized. ABS may be considered as a modifier, which obviously improved some characteristics of the microchip, such as the hydrophilicity and the electro-osmotic flow (EOF). The detection limit of Rhodamine 6G dye for the modified microchip on the home-made microchip analyzer showed a dramatic 100-fold improvement over that for the unmodified PMMA chip. A detection limit of the order of 10(-20) mole has been achieved for each injected phiX-174/HaeIII DNA fragment with the baseline separation between 271 and 281 bp, and fast separation of 11 DNA restriction fragments within 180 seconds. Analysis of a PCR product from the tobacco ACT gene was performed on the modified microchip as an application example.

Ocorrência e correção de deficiência de ferro em (Arachis pintoi) em latossolo amarelo.

Em uma pequena quadra de seringueiras jovens, plantadas em 1993, na Embrapa Amazonia Ocidental, o solo apresentava sinais de erosao laminar, apesar da pequena pendente. Como tentativa para contornar esse problema, foi escolhido Arachis pintoi como planta de cobertura, por nao ser escandente e apresentar razoavel tolerancia a sombreamento. Porem, essa tentativa na quadra de seringueiras jovens nao teve o exito esperado, devido a ausencia de modulacao, inclusive nas margens fora dessa quadra, onde o A. pintoi nao apresentou carencia de ferro. Com a necessidade de aplicacao de nitrogenio, para evitar perda por volatilizacao, foi necessario fazer coroamento das plantas, o que tornou essa operacao extremamente dificil por causa do tapete de ramos superpostos e enraizados.

Sistemas agroflorestais de seringueira com cafeeiro.

Esta publicacao tem por objetivo reunir as informacoes disponiveis na literatura sobre os sistemas agroflorestais de seringueira com cafeeiro, de modo a auxiliar os agricultores e extensionistas nas tomadas de decisoes e servir como referencial para pesquisas futuras nessa area. Sao discutidos os aspectos economicos e tecnicos das culturas, tais como: exigencias de clima e solo, compatibilidade vegetativa e fitossanitaria, materiais geneticos, tipos de sistemas, indice de equivalencia de area e praticas de manejo, visando a viabilidade tecnica e economica das culturas e dos sistemas como um todo.

Escolha da área para plantio de seringueira no Cerrado.

2001

Perspectivas da cultura da seringueira no Cerrado.

2001

Abertura de painel de sangria de seringueira com raspador de casca.

2001

Desempenho de clones de seringueira sob diferentes sistemas de sangria.

Este trabalho teve como objetivo avaliar o crescimento e a producao da borracha de clones seringueira [Havea brasiliensis ( Wild. Ex Adr. De Juss.) Muell. Arg.] sob diferentes sistemas de sangria, em condição de Cerrado dos Municipios de Barro Alto Goianesia no Estado de Goais. O plantio foi feito em fevereiro de 1992, no espacamento de 8,0 x 2,5 m (500 plantas/ha), em talhoes de 8 a 10 hectares para cada um dos clones RRIM 600, GT 1, PB 217, PB 235, PR 107 e PR 255 os quais receberam as mesmas praticas de manejo. Aos oito anos de idade, foram feitas as seguintes avaliacoes: estande final; circunferencia do caule a 1,20 m do solo; porcentagens de plantas aptas a sangria; producao de borracha acumulada na caneca pesada mensalmente; incidencia de seca de painel. A producao foi avaliada em nove sistemas de sangria em meia espiral (1/2 S), praticados cinco dias por semana (5d/7) e 10 meses ao ano (10m/12), variando na frequência de sangria (d/4 e d/7 = a cada 4 e 7 dias), a concentracao de Ethephon (ET 0,25%, 2,5%,3,3% e 5,0%) e sua frequencia de aplicacao durante o periodo chuvoso ( a cada 22, 28 e 35 dias), como segue: 1) 1/2S, d/7, ET 2,5% a cada 22 dias; 2)1/2S, d/7, ET 2,5% a cada 30 dias (referncia); 3) 1/2S. d/4, ET 2,5% a cada 30 dias; 4) 1/2S, d/7, ET 3,3% a cada 22 dias; 5)1/2S, d/7, ET 3,3% a cada 30 dias; 6) 1/2S. d/7, ET 5,0% a cada 22 dias 7) 1/2S, d/7, ET 5,0% a cada 30 dias; 8) 1/2S, d/7, ET 5,0% a cada 35 dias; 9) 1/2S, d/7, ET 0,25% (pulverizando 10 ml por painel) a cada 22 dias. Nos sistemas 1 a 8, o Ethephon foi pincelado ( 1mL) na canaleta de corte e ate 2 cm acima dela (Pa e La). O delineamento experimental foi de blocos ao acaso, com quatro repeticoes de 10 plantas poe parcela. Cada clone constitui um experimento separado, sendo os resultados de producao acumulada anual submetidos a analise de variancia e, nos caso de significancia, as medias dos sistemas foram comparadas pelo teste Tukey, ao nível de 5% de probabilidade. Nao foi constatada qualquer incidencia de seca de painel e os resultados possibilitaram as seguintes conclusoes para as condicoes da regiao: 1) o sistema 1/2S, d/7, ET 2,5% a cada 30 dias e o mais indicado par a sangria dos clones PR 255, PR 107, PB 235, PB 217 e GT 1; 2) o sistema 1/2S, d/7, ET 3,3% a cada 30 dias e o mais indicado para a sangria do clone RRIM 600; 3) a producao individual de borracha em kg/planta/ano e maior nos clones RRIM 600, PB 217 e PR 255, enquanto a producao total em kg/ha/ano e superior nos clones RRIM 600 e PB 235; 4)os clones PB 217 e PR 255 sao menos adaptados a regiao, apresentando menores valores de estande final, circunferencia do caule, porcentagem de plantas em sangria e de producao total de borracha por hectare.

Ocorrência e controle da vaquinha em seringais em formação.

O controle da vaquinha é difícil por ser um inseto que se alimenta de muitas plantas e apresenta grande mobilidade. No entanto, a aplicação de produtos a base de Tricloform ou Carbaril, principalmente nos foliolos jovens, diminui os prejuízos causados pelo ataque da praga.