如何造就未来的工程师——从激光感应线开始

<正>有机会尝试使用实际工程设计工具的学生更有希望将来在工程设计方面有所作为美国教育有一个令人不安的趋势,那就是孩子们不想成为工程师。在即将毕业的高中生中,有兴趣以工程为职业的学生已为数不多。大学电气和计算机工程专业的招生人数不断减少。最令人担忧的是,最近十年来,工     

Towards the construction of an eigenvalue engine

In this paper a new algorithm for the computation of the eigenvalues of real symmetric matrices is presented. The algorithm may be expressed in terms of a collection of communicating process and is suitable for implementation as a dedicated engine constructed from a network of transputers. However, it can also be efficiently implemented on a multiprocessor supercomputer such as the CRAY X-MP or on a set of interconnected SIMD machines.     

High temporal resolution rainfall–runoff modeling using long-short-term-memory (LSTM) networks

Neural Computing and Applications - Accurate and efficient models for rainfall–runoff (RR) simulations are crucial for flood risk management. Most rainfall models in use today are...     

薄层毛细渗透技术测定多孔性固体颗粒的表面能成分

研究了用薄层毛细渗透技术测定多孔性颗粒的表面张力和表面张力成分。以多孔性薄层硅胶板作模拟体系，以1-溴代萘和二碘甲烷作探针液体求得的硅胶表面张力的非极性成分完全一致；基于甲酰胺-水、乙二醇-水、甲酰胺-乙二醇3对探针液体求得的硅胶表面张力的极性成分彼此很好地符合。由此得到硅胶的总表面张力和表面张力的各成分分别为：rs^T=48．2mN／m，rs^LW=41．4mN／m，rs^AB=6．78mN／m，rs^ =1．65mN／m和rs^-=6．97mN／m，且rs^T与基于硅胶板归一化润湿速度-液体表面张力曲线最高点所得值完全符合。     

FUNGAL-INDUCED REDISTRIBUTION OF KRAFT LIGNIN MOLECULAR WEIGHT BY MULTI-ANGLE LASER LIGHT SCATTERING

Culture broths from Phanerochaete chrysosporium and Trametes cingulata, combined with co-factors such as hydrogen peroxide, dithiothreitol, copper, iron, and manganese ions were examined for the ability to modify lignin structure. High-performance size exclusion chromatography (HP-SEC) coupled to multi-angle laser light scattering (MALLS) detection was used to determine the effect of several white rot fungi, pH values, enzymes, and co-factors on the molecular weight distribution of treated kraft lignin. The analytical procedure tracked changes in molecular weight distribution, radius of gyration, and hydrodynamic radius. Results showed changes in the molecular weight distribution of lignin components when treated with combinations of factors. The induced cultures showed more lignin depolymerization for the specific lignin samples in which they were initially grown. The distribution in the radius of gyration became narrower with time, indicating that molecular conformation changed to a more uniform molecular shape. H₂O₂ and DTT showed the most significant changes in lignin molecular weight distribution.     

InP nanowire/polymer hybrid photodiode

A novel design is presented for a nanowire/polymer hybrid photodiode. n-InP nanowires are grown directly onto an indium tin oxide (ITO) electrode to increase carrier collection efficiency and to eliminate the need for an expensive substrate. Experiments show that an ohmic contact is achieved between the nanowires and the ITO electrode. The nanowires are then enveloped by a high hole mobility conjugated polymer, poly(3-hexylthiophene). Compared to the control polymer-only device, the inclusion of InP nanowires increases the forward bias current conduction by 6-7 orders of magnitude. A high rectification ratio of 155 is achieved in these photodiodes along with a low ideality factor of 1.31. The hybrid device produces a photoresponse with a fill factor of 0.44, thus showing promise as an alternative to current polymer solar cell designs.     

Impact of lignin composition on cell‐wall degradability in an Arabidopsis mutant

An Arabidopsis mutant that does not deposit syringyl‐type lignin was used to test the hypothesis that lignin composition impacts cell‐wall degradability. Two lines of the ferulate‐5‐hydroxylase‐deficient fah1 mutant and the wild‐type control line were grown in the greenhouse. In Experiment 1, the plants were harvested at the mature seed stage. For Experiment 2, plants were harvested 5, 6, 7 and 8 weeks after sowing. In both experiments stems were collected and analysed for cell‐wall concentration and composition, and in vitro degradability of cell‐wall polysaccharide components by rumen micro‐organisms. The absence of syringyl‐type lignin was confirmed for the mutant lines by nitrobenzene oxidation and pyrolysis‐GC‐MS. Lignin concentration was the same for all three Arabidopsis lines, at all stages of maturity. The Arabidopsis stems were similar to forage legumes in that the potentially degradable cell‐wall fraction was very quickly degraded. Cell‐wall polysaccharide degradability did not differ among the Arabidopsis lines in the first experiment after 24‐h fermentations, but the cell‐wall polysaccharides of the fah1‐2 mutant line were less degradable after 96‐h than either the wild‐type or the fah1‐5 mutant. In contrast, in Experiment 2 no differences among lines were found for cell‐wall polysaccharide degradability after either 24‐ or 96‐h fermentations; however, signficantly higher levels of ester‐bound ferulic acid were found in the walls of the fah1 mutant lines. As expected, increasing stem maturity was correlated with reduced degradation of cell‐wall polysaccharides. These experiments indicate that either lignin composition, as measured by syringyl‐to‐guaiacyl ratio, does not alter cell‐wall degradability in Arabidopsis, or that the fah1 mutation has other effects on the cell walls of these mutants such that the impact of the change in syringyl‐to‐guaiacyl ratio is masked. © 1999 Society of Chemical Industry     

Zwitterionic poly(carboxybetaine) microgels for enzyme (chymotrypsin) covalent immobilization with extended stability and activity

There is emerging evidence that biocompatible zwitterionic materials can prevent nonspecific interactions within protein systems and increase protein stability. Here, a zwitterionic microgel was synthesized from poly (carboxybetaine methyl methacrylate) (pCB) using an inverse emulsion, free radical polymerization reaction technique. The microgel was loaded with a model enzyme, α-chymotrypsin (ChT), using a post-fabrication loading technique. A reaction scheme was developed and studied for covalent immobilization of ChT within the microgel. Confocal laser microscopy studies showed that immobilized ChT (i-ChT) was distributed within the hydrogel. The enzyme-immobilized microgels showed excellent reusability (72% of its initial activity after 10 uses) and could undergo several freezing/drying/rehydration cycles while retaining enzymatic activity. The i-ChT activity, half-life, and conformational stability were studied at varying pH and temperatures with results compared to free ChT in buffer. ChT immobilized within pCB hydrogel showed increased enzymatic stability as observed by a 13°C increase in the temperature at which i-ChT loses activity compared to free ChT. Furthermore, enzyme half-life increased up to seven-fold for the pCB immobilized ChT, and the increased stability resulted in higher activity at elevated pH. The i-ChT was most active at pH of 8.5 and was partially active up to the pH of 10.2.     

Defining the good life following acquired physical disability.

The objective of this article is to provide empirical and theoretical perspective on what attitudes and behaviors could constitute living a good life following acquired physical disability. We define the term "the good life"; briefly examine the construct's role in philosophy, history, and positive psychology; and then suggest links to rehabilitation psychology. We review variables presumed to be both predictive of and important to living well, noting that relatively few have pronounced effects on well-being. Across time, people tend to adapt to both positive and negative events. Following the onset of disability, however, people do not necessarily return to their baseline levels of well-being. To live a good life with disability, we illustrate some choices and actions that individuals can take within three defining areas: making connections with others, developing positive traits, and enacting life regulation qualities. We conclude by suggesting how understanding the nature of the good life following disability onset can inform rehabilitation theory and therapy, and aid clients and families. (PsycINFO Database Record (c) 2010 APA, all rights reserved)