The production and characterization of poly(lactic acid) fibers dyeable with anionic dyes using octaammonium polyhedral oligomeric silsesquioxane nanoparticle

In this study, acid dyeable poly(lactic acid) (PLA) fiber was produced with the addition of octaammonium polyhedral oligomeric silsesquioxane (OA-POSS) nanoparticle during the melt spinning. The tensile, thermal and morphological properties of the fiber samples were characterized by tensile testing, differential scanning calorimetry, scanning electron microscopy and transmission electron microscopy. Two different anionic dyes, a disulphonated 1:2 premetallised acid dye and monosulphonated non-metallised, were used. The effects of dyeing conditions including dyeing temperature and time, OA-POSS concentration, anionic dye types and concentrations were investigated on the dyeability properties of the PLA fiber samples. It was concluded that the percent crystallinity and the tensile strength of pure PLA fiber decreased as the added amount of OA-POSS increased. According to the dyeing results, the addition of OA-POSS greatly improved the dyeability of the PLA fiber with anionic dyes by introducing ion–ion interaction between the terminal ammonium groups of POSS nanoparticle and the sulphonyl groups of dye molecules.     

Effect of phosphoric acid and acetic acid addition on the hydrogen evolution using Ni based catalyst prepared in ethanol,methanol, and water solvents

Ni-based catalysts were synthesized in water, methanol and ethanol solvents by chemical reduction with sodium borohydride (NaBH₄). The obtained catalyst for the first time was used to catalyze the NaBH₄ hydrolysis reaction with phosphoric acid and acetic acid including different concentrations. The maximum hydrogen production rates obtained in the hydrolysis reaction including 0.5 M phosphoric acid and 0.1 M acetic acid of the Ni-based catalyst prepared in ethanol solvent were 5214 and 3650 ml g^?1 min^?1, respectively.     

s-Domain analysis of lightning surges in three-phase systems using nonuniform single-phase line model

Surge response of the transmission tower in a three-phase transmission system is computed using s-domain nonuniform single-phase transmission line modelling. First, tower top voltage is obtained considering the tower and the ground wire by excluding the effect of the phase conductors, and then the induced voltages on the phase conductors as a result of the current flowing through the ground wire are computed using the magnetic coupling between the ground wire and the phase conductors. The first step of the analysis is the formulation of the system response in the s-domain, and the second step is the frequency to time domain conversion, which is carried out using fast inverse Laplace transform (FILT). The voltages on the phase conductors and the voltages across the tower insulators are computed, and some of the results obtained using s-domain analysis are compared with those obtaining using electromagnetic transients program (EMTP). The effect of frequency dependence of the line parameters is investigated.     

Effective parametric control laws for market economy mechanisms

Parametric control for market economy mechanisms is studied under the assumption that effective algorithms are chosen from separate extremal problems.Translated from Avtomatika i Telemekhanika, No. 3, 2005, pp. 105–112.Original Russian Text Copyright © 2005 by A. Ashimov, As. Ashimov, Borovskii, Volobyeva.This paper was recommended for publication by D.A. Novikov, a member of the Editorial Board     

Service-specific resource allocation in WDM networks with quality constraints

The need to establish wavelength-routed connections in a service-differentiated fashion is becoming increasingly important due to a variety of candidate client networks (e.g., IP, SDH, ATM) and the requirements for QoS-delivery within transport layers. The multiservice operation changes the way we deal with wavelength-routed paths, as they are now being characterized by manifold properties, such as transmission quality, restoration, network management, and policies. We propose a generic approach to service-differentiated connection accommodation in wavelength-routed networks where, for the network state representation, the supplementary network graphs are defined and referred to as service-specific wavelength-resource graphs. These graphs are used for the appropriate allocation of wavelengths on concatenated physical resources building a wavelength route, along which the necessary transmission quality is achieved and the required management and surveillance functions are provided. By considering twofold wavelength routing metrics, i.e., QoS metrics (service requirements) and resource metrics (quality constraints), these graphs can yield the solution to the QoS-routing problem, i.e., the provision of service-specific guarantees under quality constraints-a feature that is still missing from the existing architectures. The numerical analysis of dynamically reconfigurable multiservice WDM networks is presented for regular network operation as well as for optical network service restoration.     

Low-threshold ZnSe microdisk laser based on fluorine impurity bound-exciton transitions

Impurity states in semiconductors, in which two long-lived ground states can be optically coupled to a single excited state, provide a powerful mechanism for applications including lasing without inversion, electromagnetically induced transparency, and optically addressable quantum memory for quantum information processing. We report low-threshold lasing from fluorine-doped ZnMgSe/ZnSe quantum wells in microdisk cavities. The lasing mechanism was studied by power-dependent photoluminescence spectroscopy. Lasing thresholds lower than 50 W cm⁻² were observed and the fraction of spontaneous emission contributed to the lasing modes was about β=0.03-0.1.