PREDICTION OF CRITICAL PROPERTIES OF 1-HEXENE/HEXENE ISOMERS/CARBON DIOXIDE MIXTURES WITH A CUBIC EOS: SENSITIVITY TO MIXTURE COMPOSITION AND TO THE PATH OF APPROACH TO CRITICAL POINTS

Critical loci of 1hexene/CO₂ and (hexene isomer pseudo-component)/CO₂ binary mixtures, along with the critical properties of the ternary mixture of CO₂/l-hexene/(hexene isomer pseudo-component) were predicted using Gibbs' thermodynamic criteria for criticality in conjunction with the Peng-Robinson (P-R) EOS. Maximum deviation in the critical pressures of the l-hexene/CO₂ binary mixture is less than 2% from reported experimental values. The addition of hexene isomer to the l-hexene/CO₂ binary and the path of approach to mixture critical points are shown to have surprisingly strong effects on predicted mixture critical properties. For a given ternary mixture, multiple critical points are predicted depending upon the isopleth (either constant CO₂ mole fraction path or constant 1-hexene mole fraction path) along which the critical point is approached. Critical densities predicted along the CO₂ isopleth of approach to critical points are always smaller than the ones predicted along the 1-hexene isopleth of approach. Furthermore, upon hexene isomer addition to the l-hexene/CO₂ binary, whereas the predicted critical property surfaces of the ternary system vary monotonically along the CO₂ isopleth of approach, extrema in these surfaces are predicted when approaching the mixture critical points along 1-hexene isopleths. These anomalous predictions are attributed to the inability of the cubic EOS to accurately model the phase behavior near the critical point.     

Decrystallization and acetylation and benzoylation of cotton fibers

The general effects of chemical modification such as acetylation and benzoylation on cotton yarns and fabrics are described and it is demonstrated that the physical properties of yarns and fabrics in terms of their elongation, moisture regain, friction, abrasion resistance, and recovery are enhanced significantly. Thermal analysis data show that benzoylated sample is the most stable product.     

Uniform waveband assignment in optical mesh networks

The cost of an optical network in wavelength division multiplexing (WDM) networks can be reduced using optical reconfigurable optical add/drop multiplexers (ROADMs), which allow traffic to pass through without the need for an expensive optical-electro-optical (O-E-O) conversion. Waveband switching (WBS) is another technique to reduce the network cost by grouping consecutive wavelengths and switching them together using a single port per waveband. WBS has attracted the attention of researchers for its efficiency in reducing switching complexity and therefore cost in WDM optical networks. In this paper, we consider the problem of switching wavelengths as non-overlapping uniform wavebands, per link, for mesh networks using the minimum number of wavebands. Given a fixed band size b _s , we give integer linear programming formulations and present a heuristic solution to minimize the number of ROADMs (number of wavebands) in mesh networks that support a given traffic pattern. We show that the number of ROADMs (or number of ports in band-switching cross-connects) can be reduced significantly in mesh networks with WBS compared to wavelength switching using either the ILP or the heuristic algorithm. We also examine the performance of our band assignment algorithms under dynamic traffic.     

Effects of enzymatically-extracted purple rice bran fiber as a protectant of L. plantarum NRRL B-4496 during freezing,freeze drying,and storage

This study investigated purple rice bran fiber (PRF) as a protectant for Lactobacillus plantarum NRRL B-4496 (LP) during freezing, freeze drying and storage. PRF was enzymatically extracted from purple rice bran. L. plantarum NRRL B-4496 was grown in MRS broth, centrifuged, and immobilized on PRF suspension. LP cells immobilized on PRF (LP-PRF) and free LP cell (control) samples were frozen in either air blast (AF) or cryogenic freezing (CF) before freeze drying. Freeze-dried (FLP) samples were stored either at room temperature or at refrigerated temperature. For either freezing method, PRF protected cells had less than one log reduction of viable cells while the control had reductions greater than six logs after freeze drying. The log reductions of viable LP cells protected with PRF after freeze drying and 12 weeks storage at 4° C for AF and CF treatments were 0.7 and 1.3 log cycle, respectively. The viable LP-PRF cell count for CF was significantly lower than for AF after 12 weeks at room temperature. PRF improved LP survival in both AF and CF samples in bile. This study demonstrated that freezing methods affected LP viability during storage and that PRF could protect at both refrigerated and room temperatures.     

Biochemical Neuroadaptations in the Rat Striatal Dopaminergic System after Prolonged Exposure to Methamphetamine Self-Administration

Perturbations in striatal dopamine (DA) homeostasis might underlie the behavioral and pathobiological consequences of METH use disorder in humans. To identify potential consequences of long-term METH exposure, we modeled the adverse consequence DSM criterion of substance use disorders by giving footshocks to rats that had escalated their intake of METH during a drug self-administration procedure. Next, DA D1 receptor antagonist, SCH23390 was injected. Thereafter, rats were euthanized to measure several indices of the striatal dopaminergic system. Footshocks split the METH rats into two phenotypes: (i) shock-sensitive that decreased their METH-intake and (ii) shock-resistant that continued their METH intake. SCH23390 caused substantial dose-dependent reduction of METH taking in both groups. Stopping SCH23390 caused re-emergence of compulsive METH taking in shock-resistant rats. Compulsive METH takers also exhibited greater incubation of METH seeking than non-compulsive rats during withdrawal from METH SA. Analyses of DA metabolism revealed non-significant decreases (about 35%) in DA levels in resistant and sensitive rats. However, striatal contents of the deaminated metabolites, DOPAL and DOPAC, were significantly increased in sensitive rats. VMAT2 and DAT protein levels were decreased in both phenotypes. Moreover, protein expression levels of the D1-like DA receptor, D5R, and D2-like DA receptors, D3R and D4R, were significantly decreased in the compulsive METH takers. Our results parallel findings in post-mortem striatal tissues of human METH users who develop Parkinsonism after long-term METH intake and support the use of this model to investigate potential therapeutic interventions for METH use disorder.     

Solid phase extraction of chromium(VI) from aqueous solutions by adsorption of its ion-association complex with cetyltrimethylammoniumbromide on an alumina column

A simple approach has been developed for the solid phase extraction of chromium(VI) based on the adsorption of its ion-association complex with cetyltrimethylammoniumbromide (CTABr) on an alumina column. The effect of various parameters such as acidity, stability of the column, sample volume, effect of diverse ions, etc. have been studied in detail. The adsorbed complex could be eluted using sodium hydroxide and the concentration of chromium has been established using visible spectrophotometry after complexation with diphenyl carbazide. The calibration graph was linear in the range 0-0.5 microg mL(-1) chromium(VI) with a detection limit of 5 microg L(-1). A highest preconcentration factor of 25 could be obtained for 250 mL sample volume. The data from the column studies were also studied using the Thomas model of adsorption. The experimental results obtained were correlated with the proposed model of adsorption. The Thomas rate constant k was found to be 0.0025 L/min mg and the maximum adsorption capacity q(o) was found to be 0.36 mgCr/g alumina at an initial chromium(VI) concentration of 1 mg L(-1). The validity of the method has been checked by applying it to study the recovery of chromium in spiked water samples and electroplating wastewater.     

功率管理实现最优功率设计

为了实现目前的功率管理目标,需要采取一种全面的功率管理方法,下至晶体管,上至全芯片技术,悉数包含在内。     

Direct incorporation of tungsten into ultra-large-pore three-dimensional mesoporous silicate framework: W-KIT-6

Tungsten was incorporated into ultra-large-pore silicate, KIT-6, via hydrothermal synthesis method using a Pluronic P123 triblock copolymer as the structure directing agent and n-butanol as additive. The Si/W ratio in the synthesis gel was varied from 10 to 100. Calcined W-KIT-6 samples were characterized by XRD, elemental analysis, N₂ sorption, HR-TEM, XPS, DR-UV-Vis, H₂-TPR and NH₃-TPD. These samples possess surface areas ranging from 625 to 927?m²/g with corresponding pore volumes from 1.09 to 1.44?cm³/g and narrow pore size distributions from 6.3 to 6.9?nm. In all the samples, the framework incorporation of tungsten is evident from low angle XRD and DR-UV-Vis analyses. In samples with higher tungsten content, extra-framework WO₃ species were also evident from high angle XRD, Laser Raman and DR-UV-Vis studies. NH₃-TPD study revealed the presence of low to medium acid strength sites in these samples.