Group-index and resonant field enhancement in a symmetric double-sided grated waveguide

A numerical study has been carried out by means of the Green's function method to explore possible performance improvements of a simple grated waveguide (GWg) by the variations of its grated structure. It is shown that a GWg featuring symmetric two-sided grated structure of 16 teeth with a 60?nm groove depth and having a symmetric refractive index profile with a relatively large contrast between the grated and ungrated layers is capable of delivering largely improved device performance compared to that achieved previously with a one-sided grating of 40?nm groove depth and asymmetric index profile. The improvement is characterized by a remarkable 8-fold and 15-fold increase in the group index and the maximum field intensity, respectively, at the first resonance wavelength above the upper band edge (shorter wavelength), while relatively less improvement is found at the first resonance wavelength below the lower band edge (longer wavelength). It is shown that more than 20% further improvement can be obtained by an appropriate shifting of the two innermost adjacent grating teeth in the case of the 40?nm groove depth. Apart from that, the result also reveals an interesting and remarkable correlation between the variations of the group index and the confined energy.     

Extract of Irish potatoes (Solanum tuberosum L.) decreases body weight gain and adiposity and improves glucose control in the mouse model of diet‐induced obesity

Both sexes of mice were fed a high fat diet (HFD) for 10 weeks without and with polyphenolic‐rich potato extracts (PRPE) of cultivars Onaway and Russet Burbank. PRPE attenuated weight gain in male and female mice by as much as 63.2%, which was associated mostly with a reduction in adiposity. Mice receiving PRPE showed enhanced capacity for blood glucose clearance. Sex differences regarding the impact of HFD and PRPE on plasma levels of insulin, ghrelin, leptin, gastric inhibitory peptide, and resistin were noted. PRPE may serve as part of a preventative dietary strategy against the development of obesity and type 2 diabetes.     

Fourier transform infrared studies of poly(vinyl chloride) blends with ethylene Co- and terpolymers

The miscibility of poly(vinyl chloride) (PVC) with various ethylene copolymers and terpolymers were investigated using FT-IR spectroscopy. All blends reported were 50/50 by weight. In blends of PVC with ethylene/dimethyl acrylamide copolymer (E/DMA), frequency shifts were observed in the amide carbonyl (proton acceptor) and the α-hydrogen of PVC (proton donor) characteristic bands. In blends of PVC with ethylene/ethyl acrylate/carbon monoxide terpolymer (E/EA/CO), both the ester carbonyl and the ketone carbonyl characteristic frequencies showed mutual shifts and appeared as if they merged together. Small frequency shifts were also observed in the α-hydrogen of PVC characteristic bands. In blends of PVC with ethylene/vinyl acetate/carbon monoxide terpolymer (E/VA/CO), the ester carbonyl frequency showed a shift while that of the ketone carbonyl was essentially unchanged. On the other hand, in PVC blends with ethylene/vinyl acetate copolymer (E/VA), the ester CO frequency did not show any shift, which is consistent with their observed immiscibility. Thus, it is clear that incorporating a ketone ? C?O in ethylene/ester copolymers to form the corresponding terpolymers enhances their miscibility with PVC as earlier proposed on the basis of dynamic mechanical studies. Similar results were shown for blends of PVC with ethylene/2 ethyl hexyl acrylate/carbon monoxide terpolymer (E/2EHA/CO). Frequency shifts imply specific interactions which suggest polymer-polyer miscibility on a molecular scale.     

Analgesia using continuous axillary block after surgery of severe hand injuries: self-administration versus continuous injection

OBJECTIVE: To compare analgesia produced after surgery for severe hand trauma, by a continuous axillary block obtained either with a continuous injection (CA) or controlled by the patient (PCA). STUDY DESIGN: Prospective, randomized study. PATIENTS: Forty-two ASA physical class 1 and 2 patients were enrolled over a twelve-month period and randomly allocated either into the CA or the PCA group. METHODS: After recovery from the surgical block, the axillary plexus was located using a nerve stimulator and a 20 G catheter (Contiplex B Braun) inserted over 5 centimeters into the axillary sheath. In the CA group (n = 21) patients received 0.1 mL.kg-1.h-1 of 0.25% bupivacaine and in the PCA group (n = 21) patients received 0.1 mL.kg-1 boluses of 0.25% bupivacaine with a one hour lock-out period. Data collected were pain intensity rated according to he visual analog scale (VAS), the total volume of bupivacaine injected, the quantity of nalbuphine administered as 10 mg boluses when VAS was = 5, and the patient's satisfaction after removal of the catheter. Statistical analysis used Student t test, ANOVA and chi 2 test. RESULTS: The mean duration of catheter use was 5 +/- 3 days. During this period the amount of bupivacaine was significantly reduced in the PCA group when compared to the CA group (P < 0.001). Similarly, the PCA group required significantly less nalbuphine. Finally, in this group, the satisfaction index was higher than in the CA group (95 versus 52% respectively, P < 0.01). CONCLUSION: Continuous axillary plexus blockade provides safe and effective postoperative analgesia. With the PCA technique results a lower quantity of bupivacaine is required and patient's satisfaction better.     

Institutional Aspects of Water Management in Central Asia Water Users Associations

Abstract

The way water resources in the former Soviet Union (FSU) were managed in the second half of the past century had both positive and negative effects and contributed to the existing situation. On the one hand, extensive development of water resources led to the transformation of millions of hectares of virgin lands into agricultural production, providing millions of people with food and livelihoods. On the other hand, the over-exploitation of water resources led to drastic changes of the environment: many water bodies, such as lakes, small rivers, and delta wetlands dried up. The Aral Sea basin is one of the dramatic examples of the negative impacts of large-scale irrigation interventions. The state-controlled era of development in the Soviet period has a legacy of standardized procedures and rules formulated at the top. The shortcomings of such a water management included fragmentation, duplication, and a highly administrative approach without considering the needs of the environment and input of water users into planning, allocating, and managing of water resources. This paper presents an analytical view of the role and importance of water users organizations/associations (WUOs/WUAs) in the irrigated agriculture and under irrigation management transfer (IMT) in Central Asia region. International Water Management Institute (IWMI) and the Scientific Information Center of Interstate Coordination Water Commission (SIC ICWC) conducted the “Best Practices.” Projects including activities covered Syr Darya and Amu Darya basins of Central Asia. During the first stage of the project (01.04.1002-31.03.2002), the monitoring objects were: 30 district water management organizations (DWMO), eight WUAs, 58 collective farms (CCF), and 61 private farms (PPF) from eight provinces Central Asia) project for conserving water resources by involving water users into water savings. The primary strategy was to propagate application of inexpensive technical and managerial methods and measures to save water by users themselves. The project is a joint project of IWMI and SIC ICWC aimed to monitor and disseminate the best practices of water conservation initiated by water users. The first year of the “Best Practices” project accomplished a broader involvement of water users into the water conserving methods, therefore continuing the beneficial good water management practices. It also continued to involve the water supplying organizations and various groups of water users (collective farms, farmers, and water users' associations). The major interest was to analyze the impacts of the different water conservation and management practices on productivity of water use.     

EFFECTS OF SAWDUST ON BIOGAS PRODUCTION FROM COWDUNG

ABSTRACT

The biogas generation was performed using cowdung and sawdust in the ratios of 4:1 and 2:1, respectively. The experiments were also conducted using cowdung alone for the comparison purpose. The increase in the amount of sawdust in the mixture of cowdung and sawdust decreases the quantity of gas production. The production of methane up to three weeks is also effected by the amount of sawdust. The nitrogen contents increase and volatile solids decrease with the digestion of waste materials. The thermogravimetric studies of the materials support the biogas generation as the decomposition of particular part of cowdung.     

Designing sustainable alternatives for batch operations using an intelligent simulation–optimization framework

The drive towards sustainability has compelled the batch process industries to implement the concept of environmentally friendly plants. However, the temporal nature of processing in these processes obviates the application of traditional waste minimization, material recycling, or energy integration schemes. Further, most of the existing methodologies for generating sustainable alternatives are restricted to specific problems, such as reaction byproduct, wastewater, or solvent minimization. In this paper, we propose an intelligent simulation–optimization framework for identifying comprehensive sustainable alternatives for batch processes. We differentiate between wastes generated by the reaction–separation process and cleaning wastes. A P-graph-based approach is used for identifying the root cause of process waste generation and generating broad design alternatives. Specific variable-level design solutions are then identified and evaluated using process simulation. The cleaning wastes resulting from the optimized process are also minimized using a source-sink allocation method that allows design of recycle network structure. A multi-objective stochastic optimization method is used to integrate the analysis so that the overall process economic and environmental footprint is optimized. We illustrate the proposed methodology using a well-known literature case study involving reaction, distillation and washing operation.     

Chemical and photoluminescence analyses of new carbon-based boron oxynitride phosphors

Analyses of newly developed carbon-based boron oxynitride phosphors using an electron energy-loss spectrometer and a spectroflurophotometer were carried out. The results showed that the prepared phosphor powder has covalently bonded boron, nitrogen, and oxygen atoms with a soft carbon framework. Photoluminescence characterization revealed that the resultant phosphor has a direct bandgap transition with defect broadened band edges, resulting in a high quantum efficiency, because the atomic distances of the phosphor are smaller than those of conventional carbon-based boron nitride compounds, which have an indirect bandgap transition and a low quantum efficiency. The atomic distances of the phosphor are smaller owing to the presence of oxygen atoms, which have a higher electron affinity and a smaller covalent bond radius compared with boron, carbon and nitrogen.     

Effect of Fe2O3/SiO2 ratio on maghemite-silica particulate nanocomposites

Abstract： Maghemite-silica particulate nanocomposites were prepared by modified 2-step sol-gel process. Superparamagnetic maghemite nanoparticles were successfully produced using Massart＇s procedure. Nanocomposites consisting of synthesized maghemite nanoparticles and silica were produced by dispersing the as-synthesized maghemite nanoparticles into the silica particulate form. The system was then heated at 140 ℃for 3 d. A variety of mass ratios of Fe2O3/SiO2 was investigated. Moreover, no surfactant or other unnecessary precursor was involved. The nanocomposites were characterized using XRD, BET and AGM. The XRD diffraction patterns show the reflection corresponding to maghemite nanoparticles and a visible wide band at 20 from 20° to 35° which are the characteristics of the amorphous phase of the silica gel. The patterns also exhibit the presence of only maghemite and SiO2 amorphous phase, which indicates that there is no chemical reaction between the silica particulate gel and maghemite nanoparticles to form other compounds. The calculated crystallite size for encapsulated maghemite nanoparticles is smaller than the as-synthesized maghemite nanoparticles indicating the dissolution of the nanoparticles. Very high surface area is attained for the produced nanocomposites （360-390 m^2/g）. This enhances the sensitivity and the reactivity of the nanocomposites. The shapes of the magnetization curves for nanocomposites are very similar to the as-synthesized maghemite nanoparticles. Superparamagnetic behaviour is exhibited by all samples, indicating that the size of the maghemite nanoparticles is always within the nanometre range. The increase in iron content gives rise to a small particle growth.