Formation and crosslinking of latex films through the reaction of acetoacetoxy groups with diamines under ambient conditions

We investigated the processes of film formation, polymer diffusion, and crosslinking of latex films at ambient temperature, using low T_g methacrylate latex bearing acetoacetoxy groups, and curing the systems with 1,6-hexanediamine as the crosslinker. The addition of diamine induces floc formation, which modifies the rheological properties of the dispersion and increases its drying rate when coated onto a substrate. The crosslinking reaction between diamine and acetoacetoxy groups occurs at a rapid rate, even in the dispersed state. Although the crosslinking reaction precedes polymer diffusion in the two systems we examined, latex films with relatively good solvent resistance are obtained. Department of Chemistry, Toronto, Ontario, Canada M5S 3H6. Department of Polymer Chemistry, P. O. Box 513, 5600 MB Eindhoven, The Netherlands.     

Blind separation of instantaneous mixture of sources based on orderstatistics

In this paper, we introduce a novel procedure for separating an instantaneous mixture of sources based on order statistics. The method is derived in a general context of independence component analysis, using a contrast function defined in term of the Kullback-Leibler divergence or of the mutual information. We introduce a discretized form of this contrast permitting its easy estimation through order statistics. We show that the local contrast property is preserved and derive a global contrast, exploiting only the information of the support of the distribution (in case this support is finite). Some simulations are given, illustrating the good performance of the method     

The emergence of coherence over the course of decision making.

Previous research has indicated that decision making is accompanied by an increase in the coherence of assessments of the factors related to the decision alternatives. In the present study, the authors investigated whether this coherence shift is obtained before people commit to a decision, and whether it is obtained in the course of a number of other processing tasks. College students were presented with a complex legal case involving multiple conflicting arguments. Participants rated agreement with the individual arguments in isolation before seeing the case and after processing it under various initial sets, including playing the role of a judge assigned to decide the case. Coherence shifts were observed when participants were instructed to delay making the decision (Experiment 1), to memorize the case (Experiment 2), and to comprehend the case (Experiment 3). The findings support the hypothesis that a coherence-generating mechanism operates in a variety of processing tasks, including decision making. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Power, efficiency, and thermal characteristics of type-II interbandcascade lasers

High-performance mid-infrared type-II interband cascade lasers have been demonstrated under continuous-wave (CW) conditions with record-high wall-plug efficiencies (>14%) and output powers (>100 mW/facet) above 77 K. Device characteristics of these type-II interband cascade lasers are investigated systematically in terms of their output powers and efficiencies. Also, by comparing the temperature dependence of the threshold currents under pulsed and CW conditions, the thermal resistance and maximum heat sink temperature for CW operation are estimated for several mesa sizes. The limiting factors due to device heating for high-power/high-efficiency operation are identified and discussed in connection with device dimensions and packaging for the purpose of assessing further improvements     

The single-breath nitrogen test in coal miners: factors associated with failure to perform

The objectives of this study were to determine the prevalence of musculoskeletal complaints in a population of lock assemblers in the West Midlands; to follow one group over 12 months and to explore the relationship between survey data, sickness absence information and claims experience. An adapted Nordic Musculoskeletal Questionnaire was used to determine annual and weekly prevalence and annual disability rates for musculoskeletal complaints. There was no statistically significant difference in complaints between the six companies, apart from an increased reporting of neck (p < 0.001), upper back (p < 0.001) and hip (p < 0.05) symptoms at one company (Site 4) during the week prior to the study. When the study was repeated at Site 4 one year later, new employees had significantly fewer complaints of neck and elbow discomfort over the previous year and week, but no difference in wrist complaints was reported. This survey of lock assemblers has highlighted high levels of self-reported upper limb complaints when compared to other referent groups of workers.     

Prediction of solubility of long-chain hydrocarbons in various solvents using UNIFAC

The UNIFAC group contribution model has been widely used in the prediction of phase equilibria of various fluid mixtures. We have applied the method to predict the solubility of various long-chain hydrocarbon solids in a number of solvents of industrial importance. The calculated solubilities are compared with measured values and also with the predictions of the regular solution theory of Hildebrand and Scatchard. Some disagreements were found between the measured solubilities and the predicted values of both theories. Overall the UNIFAC scheme appears to be superior to the regular solution theory.Paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A.     

Chemical compositions,fine structure and physicochemical properties of kudzu (Pueraria lobata) starches from different regions

Three commercial kudzu starches from Vietnam, Japan and Korea were used to determine chemical compositions, isoflavone compounds, fine structure and physicochemical properties. The kudzu starch from Vietnam had polygonal granules, whereas the kudzu starches from Japan and Korea contained both polygonal and spherical granules. Total protein, lipid, ash and phosphorus contents present in these kudzu starches were less than 1% (starch basis). The kudzu starch from Vietnam and Korea contained both daidzein and daidzin, whereas the kudzu starch from Japan had only daidzein. These starches had similar actual amylose contents (22.2–22.9%). However, λ_max, blue value and apparent amylose contents of the kudzu starch from Vietnam were lower than those from Japan and Korea. Amylose molecules of the kudzu starch from Vietnam had the largest average degree of polymerization (DP_n) and number of chains (NC), followed by the kudzu starches from Japan and Korea. Amylopectin molecules of the kudzu starch from Vietnam also had the largest DP_n and NC, followed by the kudzu starches from Korea and Japan. X-ray diffraction patterns of the kudzu starches from Vietnam, Japan and Korea were A-type, C-type and B-type, respectively. The kudzu starch from Vietnam was found to have the specific characteristics such as significantly high gelatinization temperature, transition enthalpy and degree of crystallinity as compared to the kudzu starch from Korea and Japan.     

Calculation of DC Magnetic Flux Deviation in the Converter-Transformer of a Self-Commutated BTB System During Single-Line-to-Ground Faults

This paper deals with a 50-MW self-commutated Back-To-Back (BTB) system intended for power-flow control between transmission networks. It focuses on the dynamic behavior of the BTB system during single-line-to-ground (SLG) faults that often result in voltage sags. A non-negligible amount of dc magnetic flux deviation appears in the converter-transformers of the BTB system just after the occurrence and restoration of an SLG fault. The dc deviation may bring magnetic flux saturation and an excessive magnetizing current to the transformers. This paper derives theoretical equations related to the dc deviation with reasonable approximation. The theoretical results are confirmed by computer simulation.     

Load Bearing Capacity of Reinforced Concrete Beams Subjected to Dynamic Cyclic Loads

A kinematic method is developed to determine the shakedown limits of elastic-perfectly plastic steel-reinforced concrete beams under quasi-static and dynamic cyclic loads. This procedure, like the respective kinematic approach of plastic limit analysis, is visual and easy to use in engineering applications. The load parameters (amplitudes, frequency) versus yield moment diagrams, constructed from possible collapse modes, should assist in choosing the reinforcement scheme and amounts of reinforcement to meet the load bearing requirements for the structures.