Size-exclusion Chromatography of Urea-Formaldehyde Resins

Samples of urea-formaldehyde resin have been investigated by means of size-exclusion chromatography systems: (A) Zorbax PSM packing with either pure N,N-dimethylacetamide (DMA) eluant or DMA+0.1 mol dm^?3 LiNO₃ eluant; (B) Styragel packing with DMA eluant. In addition to separation by size-exclusion, adsorption/partition and hydrodynamic effects were observed. The influence of reaction time and conditions on the production of large soluble aggregates was investigated briefly.     

A computational model for recognition of multifont word images

A computational model for the recognition of multifont machine-printed word images of highly variable quality is given. The model integrates three word-recognition algorithms, each of which utilizes a different form of shape and context information. The approaches are character-recognition-based, segmentation-based, and word-shape-analysis based. The model overcomes limitations of previous solutions that focus on isolated characters. In an experiment using a lexicon of 33,850 words and a test set of 1,671 highly variable word images, the algorithm achieved a correct rate of 89% at the top choice and 95% in the top ten choices.     

Rapid reacquisition of fear to a completely extinguished context is replaced by transient impairment with additional extinction training.

A series of experiments studied reacquisition of fear reactions to a completely extinguished context. Reacquisition was rapid when reconditioning occurred as soon as the fear reactions were completely extinguished, showing that the original conditioning was intact. However, when reconditioning occurred after massive extinction training, fear reactions were depressed but then recovered across a long retention interval. This recovery was due to reconditioning and was similar to that produced by conditioning a massively preexposed context. These results show that massive extinction converts a potentially dangerous context into one that is merely familiar. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Integrating entrapped mixed microbial cell (EMMC) technology for treatment of wastewater containing dimethyl sulfoxide (DMSO) for reuse in semiconductor industries

Solvents containing dimethyl sulfoxide (DMSO) are widely used in the rinse process of stripping photoresistors in semiconductor manufacturing industries. The disposal/reuse of wastewater containing DMSO is a serious problem because of its high concentration of organic carbon and the need to suppress the odor from its sulfur contents. An entrapped mixed microbial cell (EMMC) process was used to investigate the effectiveness of removing DMSO from a synthetic wastewater in a once-through up-flow fixed-bed bioreactor. Both cellulose triacetate and cellulose acetate were used to prepare the EMMC carriers. Various hydraulic retention times (HRTs) (based on the void volume) of 3, 4, 5, 6, and 12 h were investigated when the concentration of DMSO was 500 mg/l and 1,000 mg/l. It was found that the addition of 50 mg/l of sucrose was needed to serve as the carbon source for possible co-metabolism of DMSO. Based on the result of the impact of various dilution rates (1/HRT) on the TOC (total organic carbon) removal efficiency and TOC remaining, a dilute curve for this relationship was plotted. Thus, an optimal operational criterion was developed, i.e., it must be operated at a dilution rate of less than 0.15 h⁻¹ or at an HRT of higher than 6.66 h, in order to achieve more than 95% of TOC (or more than 99% of DMSO) removal efficiency when using the cellulose triacetate as the EMMC carriers. This process performance was compared to the bio-contact filter (BCF) process conducted in Japan. It was found that the present study is capable of producing much less effluent nitrogen (including NH₄-N and NO₃-N) content than the BCF process under similar loading conditions. It is possible that integrating the unit process of EMMC as pretreatment with microfiltration (MF) and reversed osmosis (RO) processes is promising for the reuse and recycling of semiconductor wastewater. Thus, higher quality (less organic carbon and inorganic nitrogen content) pretreated water can be further treated by another physical chemical process, such as MF and RO, for the production of superpurity water for reuse in the semiconductor manufacturing industry.     

Accurate prediction of scorpion toxin functional properties from primary structures

Scorpion toxins are common experimental tools for studies of biochemical and pharmacological properties of ion channels. The number of functionally annotated scorpion toxins is steadily growing, but the number of identified toxin sequences is increasing at much faster pace. With an estimated 100,000 different variants, bioinformatic analysis of scorpion toxins is becoming a necessary tool for their systematic functional analysis. Here, we report a bioinformatics-driven system involving scorpion toxin structural classification, functional annotation, database technology, sequence comparison, nearest neighbour analysis, and decision rules which produces highly accurate predictions of scorpion toxin functional properties.     

Reliability Prediction Techniques for Complex Systems

As electronic systems continue to evolve into more and more complex structures, the search for better and more efficient reliability prediction techniques naturally takes on added momentum. Needed are not only systematic methods of mathematical model building that will simplify the procedures involved but also noncomplex ways of obtaining solutions to many practical problems. This paper illustrates the applicability of transition diagram in describing the state space of a complex system, repairable or nonrepairable, and shows the methodology of writing the set of first-order linear differential equations representing the system performance by inspection of the transition diagram. A discussion of some applicable properties of linear signal-flow graphs is included. Methods of solving problems by inspection techniques are clearly explained and specific examples are given to illustrate the concepts. The mean time Tm for a system to pass for the first time from its initial state to a failed state is usually a statistic of prime interest. Certain properties of Laplace transform are used to illustrate how Tm of a general complex system, repairable or nonrepairable, can be obtained by solving a set of simultaneous algebraic equations. Flow graph techniques of solution by inspection are shown to be a valuable tool in obtaining analytical solutions for Tm of many practical systems.     

Determination of Surface Tension of Succinonitrile Using a Surface Light Scattering Spectrometer

Liquid/vapor interfacial surface tensions of succinonitrile, NC(CH₂)₂CN, were measured using noninvasive surface light scattering (SLS) spectroscopy. Succinonitrile (SCN) has been and is being used extensively in materials science and fluid physics research, for example, in several theoretical and numerical studies of dendritic growth. It is an established model material with several essential physical properties accurately known with the exception of the liquid/vapor surface tension, _1v, at various temperatures. Using the SLS spectrometer, we have experimentally determined the liquid/vapor surface tension of SCN in the temperature range from just above its melting point (58.1°C) to 118°C using this noninvasive method. Previous measurements of SCN surface tension are extremely limited. To the best of our knowledge, this work is the first to measure the surface tension of succinonitrile noninvasively at melt and elevated temperatures. The SLS spectroscopy is relatively new and unique. This technique has several advantages over classical methods: it is noninvasive, has a good accuracy, and can be used to measure the surface tension and viscosity simultaneously, although the viscosity results are not discussed here. The accuracy of values obtained from this technique on some standard liquids is better than 2% for the surface tension and about 10 to 15% for viscosity. Our measurements gave _1v=42.28–0.0629T±0.2 (mN·m^-1), with T in °C, and the viscosity at 60°C is 2.68±0.3 cp for pure SCN.     

Effects of Ru on the high-temperature phase stability of Ni-base single-crystal superalloys

Microstructural instabilities associated with the precipitation of refractory-rich topologically-close-packed (TCP) phases within the microstructure of advanced Ni-base single-crystal superalloys were quantified in two nominally identical alloys with and without additions of Ru. Differences in the microstructural kinetics associated with the formation of TCP precipitates in these experimental single-crystal superalloys enabled the influence of Ru to be assessed. Detailed microstructural investigations were carried out on specimens subjected to prolonged isothermal exposures at elevated temperature. Even after 1000 hours at temperatures in excess of 1100 °C, the microstructure of the Ru-bearing alloy was highly resistant to the formation of TCP phases. Transmission electron micro-analysis (TEM) coupled with X-ray diffraction (XRD) was used to identify the characteristic crystal structures of the TCP precipitates in both alloys as being primarily the orthorhombic P and tetragonal σ phase. The sluggish precipitation kinetics of TCP phases in the Ru-bearing single-crystal Ni-base superalloy prevents the breakdown of the parent γ-γ′ microstructure and greatly enhances the high-temperature creep characteristics.     

Efficient IEEE 802.11 handoff based on a novel geographical fingerprint scheme

The effective coverage distance of wireless LAN (WLAN) being small, users may leave the coverage area of the specific access point (AP) from time to time while roaming. However, the wireless network is a shared medium. The air is open for everyone. In general there is collision if a few users attempt to transmit with the same channel that is more rigorous during handoff period because of active scan mode. The active scan will perform requests for searching available AP. Unfortunately, this function consumes too much resource in wireless communication, and also affect total performance. We will propose an advanced active scan to improve it. In our proposal, we convert RF signal distribution to a simple classification problem, like as XOR classifier with artificial neural network (ANN). We combine ANN with active scan to achieve our goal. And the weight, which trained by ANN presents the connection character of geography. Moreover, the weight could be stored in AP for reusing and is called geographical fingerprint. The average enhancement of reducing the active scan area is about 62%. Copyright © 2006 John Wiley & Sons, Ltd.