Emulsification properties of polyesters and sucrose ester blends II: Alkyl glycoside polyesters

Surface active properties such as surface and interfacial tension reductions and stability of oil-in-water (o/w) and water-in-oil (w/o) emulsions by alkyl glycoside fatty acid polyesters, a potential fat substitute, and emulsifier blends of alkyl glycoside polyesters and Ryoto sugar esters were investigated. Our results indicate that blending of lipophilic and hydrophilic emulsifying agents produces a synergistic effect on reduction of surface and interfacial tensions and may, in some cases, result in more stable emulsions. Alkyl glycoside polyesters may be suitable for w/o emulsions, such as margarine and butter, and their blends with hydrophilic emulsifiers will produce reduced calorie emulsifiers suitable for use in o/w emulsions, such as salad dressing. There appears to be great potential for using such emulsifier blends in food, cosmetics and pharmaceutical applications.     

Design and Configuration Rationales for Digital Video Storage and Delivery Systems

Recent advances in computing technology have brought multimedia information processing to prominence. The ability to digitize, store, retrieve, process, and transport analog information in digital form has changed the dimensions of information handling. Several architectural and network configurations have been proposed for efficient and reliable digital video delivery systems. However, these proposals succeed only in addressing subsets of the whole problem. In this paper, we discuss the characteristics of video services. These include Cable Television, Pay-Per-View, and Video Repository Centers. We also discuss requirements for Video On Demand services. With respect to these video services, we analyze two important video properties: image quality and response time. We discuss and present configurations of a Digital Video Delivery System (DVDS) from three general system components - servers, clients, and connectivities. Pertinent issues in developing each component are also analyzed. We also present an architecture of a DVDS that can support the various functionalities that exist in the various video services. Lastly, we discuss data allocation strategies which impact performance of interactive video on demand (IVOD). We present preliminary results from a study using a limited form of mirroring to support high performance IVOD.     

A two-term MEDLINE search strategy for identifying randomized trials in obstetrics and gynecology

In this study, we examined whether endothelin (ET) plays a role in the short-term increase in mean arterial pressure (MAP) after nitric oxide synthase (NOS) inhibition with N(omega)-nitro-L-arginine methyl ester (L-NAME) in stroke-prone spontaneously hypertensive rats (SHRSPs). Experiments were performed by using Inactin-anesthetized male SHRSPs that were pretreated with chlorisondamine to block reflex autonomic cardiovascular effects. Injection of L-NAME (10 mg/kg, i.v.), but not D-NAME, produced rapid and marked increases (74 +/- 3 mm Hg) in MAP that were sustained for >1 h. In SHRSPs that were treated with the ET(A/B) receptor antagonist, L-754,142 (15 mg/kg + 15 mg/kg/h), L-NAME increased MAP by 45 +/- 4 mm Hg (p < 0.0001 compared with L-NAME alone). L-754,142 blocked pressor responses to big ET-1 by >90% but was without effect on pressor responses to norepinephrine. Plasma levels of ET-1 averaged 5 +/- 1 pg/ml in animals given vehicle and were slightly increased in animals given either L-NAME alone (7 +/- 2 pg/ml) or L-754,142 alone (7 +/- 2 pg/ml) but increased markedly when L-NAME and L-754,142 were given together (114 +/- 18 pg/ml). This may relate to an effect of L-754,142 to block ET-receptor-mediated clearance of ET-1. We conclude that ET plays a role in the short-term pressor response after NOS inhibition in SHRSPs.     

Lipase G-Catalyzed synthesis of monoglycerides in organic solvent and analysis by HPLC

Monoglycerides were synthesized with Lipase G fromPenicillium sp. as biocatalyst. This enzyme successfully catalyzed the esterification of glycerol with oleic acid (18:1 n-9) or eicosapentaenoic acid, EPA (20:5 n-3) in hexane. Esterification at 40°C for 24 hr resulted in 86.3 mol% and 64.3 mol% incorporation of 18:1 n-9 and 20:5 n-3, respectively. Lipase GC fromGeotrichum candidum was not effective in esterifying the fatty acids under the present experimental conditions. Lipase G was able to incorporate 98.5 mol% and 98.1 mol% of 18:1 n-9 onto glycerol in 24 hr or less at 25°C and 37°C, respectively, in the absence of molecular sieve 4A. The product formed was analyzed by high performance liquid chromatography (HPLC) with a combined evaporative light scattering mass detector (ELSD) and ultraviolet detection at 206 nm. The result of this study demonstrates that Lipase G is capable of incorporating long-chain fatty acids of potential health benefit onto glycerol.     

Spatio-temporal effects of multimedia objects storage and delivery for video-on-demand systems

As the number of video streams to be supported by a digital video delivery system (DVDS) increases, an improved understanding of the necessity for reliable and cost-efficient support for a considerable number of video streams (in the magnitude of tens of thousands), and the dependency largely on software capabilities emerges. Even in the presence of an optimal hardware configuration, or model, and associated costs, using software to exploit the underlying hardware capabilities is of paramount importance. Although a number of DVDSs have become operational, their ability to deliver the required services mainly depends on the small number of streams supported and the hardware trade-offs. It is imperative that current software developments account for the eventual scalability of the number of video streams without commensurate increase in hardware. In this paper, we present strategies for the management of video streams in order to maintain and satisfy their space and time requirements. We use a DVDS architectural model with functionally dichotomized nodes: a single-node partition is responsible for data retrieval, while the remaining partition of nodes accepts user requests, determines object locations, and routes requests through the network that connects both partitions. We present a detailed analysis of the issues related to queuing I/O requests and data buffering. The discussion includes the requirements for arranging and scheduling I/O requests and data buffers, with the objective of guaranteeing the required data availability rates for continuous media display.     

High-pressure phase equilibria for the synthesis of ionic liquids in compressed CO2 for 1-hexyl-3-methylimidazolium bromide with 1-bromohexane and 1-methylimidazole

The use of carbon dioxide in the synthesis of ionic liquids (ILs) has many advantages over conventional solvents. Here, the high-pressure phase equilibria (including CO₂ solubility, volume expansion, and mixture critical points) are measured and modeled for the system involved in the synthesis of a model imidazolium ionic liquid 1-hexyl-3-methylimidazolium bromide ([HMIm][Br]) from 1-bromohexane and 1-methylimidazole. The global phase behavior of 1-methylimidazole was investigated and found to be a Type V system (or potentially IV) from the classification of Scott and van Konynenburg with regions of vapor–liquid equilibrium, vapor–liquid–liquid equilibrium, liquid–liquid equilibrium, an upper and lower critical endpoint and mixture critical points. The solubility and volume expansion of CO₂ in 1-methylimidazole, 1-bromohexane, a 1:1 mixture of 1-methylimidazole and 1-bromohexane and [HMIm][Br] was determined at 313.15 K and 333.15 K for pressures ranging from 10 to 160 bar. The solubility of CO₂ and the volume expansion increases in the order of [HMIm][Br]  1-methylimidazole < 1:1 mixture of reactants < 1-bromohexane. The Peng–Robinson equation of state with van der Waals 2-parameter mixing rules was used with estimated critical properties to well correlate the vapor–liquid equilibrium. The results have important ramifications on the kinetics and process constraints of an actual IL synthesis with CO₂.     

Enhanced detection and identification of glycopeptides in negative ion mode mass spectrometry

A combined mass spectrometry (MS) and tandem mass spectrometry (MS/MS) approach implemented with matrix-assisted laser desorption ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI FTICR MS) in the negative ion mode is described for enhanced glycopeptide detection and MS/MS analysis. Positive ion mode MS analysis is widely used for glycopeptide characterization, but the analyses are hampered by potential charge-induced fragmentation of the glycopeptides and poor detection of the glycopeptides harboring sialic acids. Furthermore, tandem MS analysis (MS/MS) via collision-induced dissociation (CID) of glycopeptides in the positive ion mode predominantly yields glycan fragmentation with minimal information to verify the connecting peptide moiety. In this study, glycoproteins such as, bovine lactoferrin (b-LF) for N-glycosylation and kappa casein (k-CN) for O-glycosylation were analyzed in both the positive- and negative ion modes after digestion with bead-immobilized Pronase. For the b-LF analysis, 44 potential N-linked glycopeptides were detected in the positive ion mode while 61 potential N-linked glycopeptides were detected in the negative ion mode. By the same token, more O-linked glycopeptides mainly harboring sialic acids from k-CN were detected in the negative ion mode. The enhanced glycopeptide detection allowed improved site-specific analysis of protein glycosylation and superior to positive ion mode detection. Overall, the negative ion mode approach is aimed toward enhanced N- and O-linked glycopeptide detection and to serve as a complementary tool to positive ion mode MS/MS analysis.     

The Viscosity of Nanofluids: A Review of the Theoretical,Empirical, and Numerical Models

The enhanced thermal characteristics of nanofluids have made it one of the most raplidly growing research areas in the last decade. Numerous researches have shown the merits of nanofluids in heat transfer equipment. However, one of the problems is the increase in viscosity due to the suspension of nanoparticles. This viscosity increase is not desirable in the industry, especially when it involves flow, such as in heat exchanger or microchannel applications where lowering pressure drop and pumping power are of significance. In this regard, a critical review of the theoretical, empirical, and numerical models for effective viscosity of nanofluids is presented. Furthermore, different parameters affecting the viscosity of nanofluids such as nanoparticle volume fraction, size, shape, temperature, pH, and shearing rate are reviewed. Other properties such as nanofluid stability and magnetorheological characteristics of some nanofluids are also reviewed. The important parameters influencing viscosity of nanofluids are temperature, nanoparticle volume fraction, size, shape, pH, and shearing rate. Regarding the composite of nanofluids, which can consist of different fluid bases and different nanoparticles, different accurate correlations for different nanofluids need to be developed. Finally, there is a lack of investigation into the stability of different nanofluids when the viscosity is the target point.     

Modeling Edge Heat Loss in a Flat-Plate Absorber Employed in an Indirect Solar Dryer—A 2D Galerkin Finite Element Analysis

An absorber plate is an essential component of some solar energy devices. As a primary energy conversion component, useful energy loss is not desired. The interactions and interrelationship between the parameters for use, insulation thermophysical properties, and ambient parameters are pertinent in the design of solar air heaters. A 2D finite element analysis was used to quantify the influence of edge convection heat loss on a simple absorber plate model. Results showed that the performance of the air heater can be significantly affected by edge heat loss from the absorber. The average temperature of the absorber, computed from the nodal temperature profile of the absorber, rose with superior edge insulation for low values of the heat transfer coefficient of the working fluid. However, when the ambient temperature was high, the average temperature of the absorber increased with poor edge insulation, although this condition is irregular due to fluctuations in the ambient condition. For low values of the heat transfer coefficient of the working fluid and low ambient temperature, the nondimensional edge loss flux was negligible for the absorber with superior edge insulation, and for high values of the heat transfer coefficient of the working fluid and low ambient temperature, the nondimensional edge loss flux was high for a poorly insulated absorber.