The Structure of the Irreversibly Bound Adhesion Promoter-Substrate Interfacial Layer of γ-Aminopropylsilanetriol on Crystalline Si, as Measured by XPS and FTIR

The irreversibly bound interfacial layer deposited by the γ-aminopropysilanetriol adhesion promoter onto a crystalline silicon substrate, which remains even after profuse washing, was found by XPS to have resulted from the fragmentation and rearrangement of the original γ-aminopropylsilanetriol molecule. A mechanism is proposed, involving the homolytic scission of the terminal N-C bond. One of the subsequent reactions is believed to involve hydrogen loss by abstraction and the formation of a terminal vinyl group, which bonds to the substrate. Support for this mechanism is found in IR spectroscopy of this layer.     

Factors influencing the formation of elongated morphologies in immiscible polymer blends during melt processing

The morphology of the dispersed phase in immiscible polymer blends plays an important role in the determination of the final physical properties. This paper considers factors that influence the final state of deformation of the dispersed phase, and in particular, the formation of fibers and lamellae. Blends of polyethylene and nylon-6 were extruded by ribbon extrusion at different draw ratios. Prior to single-screw extrusion the materials were blended in a co-rotating twin-screw extruder, and the size of the dispersed phase was studied as a function of the viscosity ratio. As the blends are extruded into ribbons and drawn through the calender rolls, the morphology of the dispersed phase undergoes drastic transformations. The fiber formation is enhanced by increasing the draw ratio. At high draw ratios, long thin fibers are observed. Some biaxial deformation is obtained for the noncompatibilized systems when the extruded materials enter the calender with the maximum closing pressure applied to the rolls. The same effect is observed for the compatibilized systems with lower values of the viscosity ratio. As a general rule, it has been observed that the final dispersed phase deformation is diminished in interfacially compatibilized systems.     

EXPERIMENTAL STUDY ON MIXING: POWER CONSUMPTION AND DEGREE OF SUSPENSION

An experimental study on mixing, degree of suspension and power consumption in solid-liquid suspensions was done. A system similar to those found in anaerobic fermentation processes of animal manures was used, and an existing mixing equipment was adapted for the study. Power consumption and degree of suspension for both mechanical mixing and mixing by gas was determined. The influence of variables such as geometry, solids concentration, stirrer velocity, and gas velocity was studied, discussed, and compared to data from the literature. Best results were obtained for gas mixing, the power consumption being about one fourth of that required by mechanical agitation. Finally, extended correlations relating Power and Reynolds numbers for mechanical mixing and mixing by gas are proposed.     

Decentralized observers with consensus filters for distributed discrete-time linear systems

This paper presents a decentralized observer with a consensus filter for the state observation of discrete-time linear distributed systems. Each agent in the distributed system has an observer with a model of the plant that utilizes the set of locally available measurements, which may not make the full plant state detectable. This lack of detectability is overcome by utilizing a consensus filter that blends the state estimate of each agent with its neighbors’ estimates. It is proven that the state estimates of the proposed observer exponentially converge to the actual plant states under arbitrarily changing, but connected, communication and pseudo-connected sensing graph topologies. Except these connectivity properties, full knowledge of the sensing and communication graphs is not needed at the design time. As a byproduct, we obtained a result on the location of eigenvalues, i.e., the spectrum, of the Laplacian for a family of graphs with self-loops.     

The morphology of MoS2, WS2, Co–Mo–S, Ni–Mo–S and Ni–W–S nanoclusters in hydrodesulfurization catalysts revealed by HAADF-STEM

HAADF-STEM studies have provided detailed morphological insight regarding MoS₂, WS₂, Co–Mo–S, Ni–Mo–S and Ni–W–S nanostructures in graphite-supported catalysts. It is found that the technique allows the catalytically active edges to be imaged even for single layer metal sulfide structures. Unpromoted MoS₂ and WS₂ are predominantly present as slightly truncated triangular clusters containing only a single S–M–S layer (M = Mo, W). The addition of promoter atoms results in more heavy truncations consistent with the expected tendency for the Co–Mo–S structures to expose promoted S-type edges at the expense of unpromoted Mo-type edges. However, the HAADF-STEM (High-Angle Annular Dark-field Scanning Transmission Electron Microscopy) results show for the first time that Co–Mo–S and Ni–W–S may also expose extended high index truncations.     

Agroecological analysis and economic benefit of organic resources and fertiliser in till and no-till sorghum production after a 6-year fallow in semi-arid West Africa

A field experiment was conducted in Gampela (Burkina Faso) in 2000 and 2001 to assess the impact of organic and mineral sources of nutrients and combinations thereof in optimising crop production in till and no-till systems and to assess the economic benefit of these options. The study showed that under conditions of rainfall deficiency, the use of a single organic resource at an equivalent dose of 40 kg N ha⁻¹ better secured crop yield than the application of an equivalent amount as urea-N, while a combination of organic resources and fertiliser was better in increasing crop yield than the application of the same N amount in the form of urea. In a year of rainfall deficiency, a mix of organic resources and fertiliser in both till and no-till systems increased crop water use efficiency, with the result that the farmer was able to purchase only half of the normal quantity of N fertiliser to obtain a higher yield that he would have done when all of the N was supplied in the form of urea. Under conditions where soil N is deficient, an economic benefit was achieved when urea was combined with easily decomposable organic material (e.g. sheep dung); mixing the urea at a dose of 40 kg N ha⁻¹ with maize straw was not sufficient in alleviating the negative interaction due to the enhanced N immobilisation. The results demonstrate that the use of N fertiliser alone was risky and that a higher yield, with the accompanying economic benefit, was scarcely achieved under the prevailing rainfall conditions. The application of soil and water conservation measures can contribute greatly to increasing the economic benefit of mineral, organic or combined organic and mineral-derived nutrient application under semi-arid conditions.     

Self‐regulation during e‐learning: using behavioural evidence from navigation log files

The current paper examined the relationship between perceived characteristics of the learning environment in an e‐module in relation to test performance among a group of e‐learners. Using structural equation modelling, the relationship between these variables is further explored in terms of the proposed double mediation as outlined by Ning and Downing. These authors initially proposed that motivation and self‐regulation strategies are mediators between the perception of the learning environment and performance. In our replication and extension study, we substituted self‐reported self‐regulation with behavioural indicators of self‐regulation using navigation log files and focused on test‐taking rather than general motivation. We proposed that navigational patterns captured using log files can also help deduce self‐regulation in e‐modules and provide information in the absence of self‐reports. Path analyses provide partial support for our navigational hypotheses and the model. Implications of our results for the use of e‐module data and conclusions based on navigation are discussed.     

纳米尺寸硫化镍化学增感剂

本文发现了硫化镍纳米粒子对卤化银乳剂的化学增感作用，采用水不溶性的硫化镍纳米粒子作为化学增感剂，与水溶性的硫代硫酸钠增感剂相比，可以在乳剂灰雾增加不大的条件下明显提高乳剂的感光度和反差。     

液体消毒洗涤剂的研制

研制了具有消毒杀菌、洗涤去污双重功效的液体消毒洗涤剂 ,测定了其对金黄色葡萄球菌的杀灭效果。结果表明 ,消毒洗涤剂的杀菌效果随其浓度的增加 ,作用时间的延长而提高 ;戊二醛浓度为 2 0 0× 10 -6时 ,与金黄色葡萄球菌作用 5min ,杀灭率可达 99.99%。将消毒洗涤剂在室温下放置半年 ,戊二醛分解率为 17.3 1%