Prediction of botanical composition in grassland herbage samples by near infrared reflectance spectroscopy

Near infrared reflectance spectroscopy (NIRS) was evaluated as a method to predict the botanical composition of seminatural grassland in ‘dehesa’ systems. Samples of herbaceous biomass were harvested over four consecutive years, determining in each—by manual separation—the proportion by weight of the following taxonomic groups: grasses, legumes and the rest of the families in a single block (‘others’). After reconstructing the natural samples they were analysed by NIRS. One set of samples (calibration set) was selected for the development of the equations, assaying different mathematical treatments (log l/R, first derivative and second derivative). The ranges of coefficients of multiple determination and standard errors of calibration, respectively, for the various components were: grasses, 0.86 to 0.92 and 6.66 to 9.14; legumes, 0.77 to 0.81 and 6.82 to 7.43; and ‘others’, 0.85 to 0.88 and 8.17 to 9.54. The remaining samples not included in the development of the NIRS equations (prediction set) were used for the purposes of validating the best equations. Standard errors of performance were: grasses, 6.12; legumes, 7.56 and ‘others’, 7.70.     

原子团离子在Al_(x)Ga(1-x)As基体组分SIMS定量分析中的应用

通过检测原子团离于MCs 和MAs－（M是基体元素）对AlxGa1-xAs基体组分进行了定量的分析，考察了MIQ－156SIMS上所测这些原子团离子的能量分布及其对分析结果的影响，并对正、负SIMS测量方法做出比较。     

高速连铸工艺中的结晶器保护渣技术

论述了高速连铸工艺的技术特点及应用于高速连铸工艺的保护发展现状，阐述了高速连铸保护渣成分设计，性能要求及冶金特性，提出了高速连铸保护渣研制和应用中存在的问题及今后工作的建议。     

影响点火药点火温度的因素及其与能量输出的关系

通过对给定金属，氧化剂体系的ＤＴＡ试验，研究了影响点火药点火温度的因素，说明了它们和点火药能量输出的关系。     

稀土对WC－8Ni硬质合金性能影响的研究

研究了添加微量稀土氧化物对ＷＣ－８Ｎｉ硬质合金物理机械性能的影响。在用Ｘ射线。射、扫描电镜及透射电镜等手段对含稀土ＷＣ－８Ｎｉ合金进行显微结构分析的基础上，探讨了稀土在合金中的分布状态、对组织结构的影响及其强化机理。井指出，通过添加微量稀土氧化物，可使ＷＣ－８Ｎｉ硬质合金的物理机械性能接近和达到ＹＧ８的水平。     

Exploring the potential of word processing for non-native writers

The potential of word processing for non-native student writers is explored through an examination of effects in the categories of writing process, quantity and quality of writing, planning and prewriting, revising, conception of writing, cognitive processing, setting effects, and attitudes. It is maintained that non-native writers may benefit in significant ways from the attributes of word processing and the conditions surrounding its use in composition instruction. Martha C. Pennington holds a Ph.D. in Linguistics from the University of Pennsylvania. As Reader in English at the City Polytechnic of Hong Kong, she directs research on the learning and teaching of English as a second language. Her most recent book is a collection edited with Vance Stevens entitled, Computers in Applied Linguistics(Multilingual Matters, 1992).     

原位统计分布分析在焊接结构用大壁厚钢铸件应用性能评价中的应用

大壁厚钢铸件广泛应用于超大型焊接工程结构中,提高大壁厚钢铸件的冶金质量是确保结构安全的重要保证。为加强今后大壁厚钢铸件生产过程中的冶金质量控制,采用金属原位统计分布分析技术和热模拟技术对边长为1000mm的方形铸件进行元素分布测定及热模拟试验,并对铸件的力学性能、金相组织进行了分析,以进行使用性能评价研究。发现距离表面110mm附近存在偏析带,C、Mn、Si、P均有不同程度的富集,而含Al夹杂物较少。铸件四分之一厚度处存在明显的负偏析区。铸件心部则存在较明显的中心疏松和正偏析,同时也存在主要含Al、Ti等元素的夹杂物富集。试验结果表明溶质元素C偏析造成了铸件在不同位置连续转变曲线和拉伸性能的明显差异,并会对焊接性造成影响。金属原位统计分布分析技术可以全面反映铸件的元素偏析情况,从而更有针对性地做好质量控制措施。     

Comparison of volatile compounds produced in model cheese medium deacidified by Debaryomyces hansenii or Kluyveromyces marxianus

The aroma of a deacidified cheese medium is the result of the overall perception of a large number of molecules belonging to different classes. The volatile compound composition of (60%) cheese medium (pH 5.8) deacidified by Debaryomyces hansenii (DCM(Dh)) was compared with the one deacidified by Kluyveromyces marxianus (DCM(Km)). It was determined by dynamic headspace extraction, followed by gas chromatography separation and quantification as well as by mass spectrometry identification. Whatever the media tested, a first class of volatile compounds can be represented by the ones not produced by any of the yeasts, but some of them are affected by K. marxianus or by D. hansenii. A second class of volatile compounds can be represented by the ones produced by K. marxianus, which were essentially esters. Their concentrations were generally higher than their thresholds, explaining the DCM(Km) global fruity odor. A third class can be represented by the ones generated by D. hansenii, which were essentially methyl ketones with fruity, floral (rose), moldy, cheesy, or wine odor plus 2-phenylethanol with a faded-rose odor. The impact of methyl ketones on the DCMDh global flavor was lower than the impact of 2-phenylethanol and even negligible. Therefore, the global faded-rose odor of D. hansenii DCM can be explained by a high concentration of 2-phenylethanol.     

Analysis and prediction of traffic fatalities resulting from angle collisions including the effect of vehicles' configuration and compatibility

Although the rapid growth in light truck vehicle (LTV) sales, including minivans, sports utility vehicles (SUVs), and light-duty trucks, has not been associated with an overall increase in collisions or traffic deaths in the US, there is a need for a research program to determine whether particular types of collisions have become more frequent or injurious because of the increase in the percent of LTVs in traffic. This paper presents an analysis of the effect of the increasing number of LTV registrations on fatal angle collision trends in the US. The analysis investigates the number of annual fatalities that result from angle collisions as well as collision configuration (car-car, car-LTV, LTV-car, and LTV-LTV). The analysis uses the Fatality Analysis Reporting System (FARS) crash databases covering the period 1975-2000. Results showed that death rates differ based on the collision configuration. Time series modeling results showed that fatalities in angle collisions will increase in the next 10 years, and that they are affected by the expected increase in the percentage of LTVs in traffic. Forecast showed that the total number of annual deaths is expected to reach 6300 deaths by the year 2010 (an increase of 12% over 2000). Analysis into the configuration of the collision indicated the seriousness of angle collisions involving an LTV striking a common passenger car (LTV-car). A time series model illustrated the significance of time lag and percent of LTVs in traffic on the increase of this type of fatal collisions. Forecasts from the time series model indicated a 32% increase in deaths due to this type of collisions in the next 10 years.     

FA and tocopherol composition of Vietnamese oilseeds

Seeds of 40 oilseed species from 23 different plant families (Brassicaceae, Cucurbitaceae, Fabaceae, Sapindaceae, Malvaceae, Gnetaceae, Clusiaceae, Bruseraceae, Ranunculaceae, Convolvulaceae, Amaranthaceae, Tiliaceae, Basellaceae, Solanaceae, Umbelliferae, Labiatae, Compositae, Theaceae, Euphorbiaceae, Caesalpiniaceae, Sapotaceae, Anacardiaceae, and Connaraceae) grown in Vietnam were analyzed for oilseed oil content, FA, and vitamin E. The seed oil content varied between 0.2 g/100 g for Mangifera indica and 75.7 g/100 g for Calophyllum inophyllum, whereas only nine seeds contained more than 40% oil. The tocopherol content ranged from 26 (Sapindus mukorossi) to 9361 mg/kg (Litchi chinensis). In nine seed oils unusual FA such as conjugated, cyclopropenoic, or epoxy FA were found.