Cost-benefit analysis of power system reliability: two utility casestudies

There is an emerging recognition that utility investments and other decisions that affect electric service reliability should be explicitly evaluated on the basis of their cost and benefit implications. A cost-benefit approach that quantifies the reliability benefits of alternatives in terms of the reduction in costs resulting from unserved energy enables the evaluation of generation and transmission capacity additions on a consistent, economic basis. This approach has been applied to two utility case studies. In a case study for Pacific Gas and Electric Company, it was used to evaluate three options for maintaining reliability in a major load center-two involving local generation, and the third, a new 230 kV transmission connection. In a case study for Duke Power Company, the approach was used to evaluate alternative designs for proposed additions to a transmission station. This paper describes the methodology and presents the two utility studies     

Advanced generating technologies: motivation and selection processin electric utilities

The constant search by electric utilities for advanced methods for generating electricity to meet future demand is discussed. The primary goal is to generate electricity with minimum damage to the environment and to use resources that are abundant. The evaluation of the role of these technologies in the future utility system, considering both quantifiable and nonquantifiable benefits and risks, is discussed from the perspective of the utility planning process     

Role of carrier material in encapsulation of yeast (Saccharomyces cerevisiae) by spray drying

ABSTRACT

Yeast was encapsulated using different carrier materials and their combinations to explore the possible synergistic effect of carrier material during encapsulation using spray drying. Freeze-drying was performed for comparison. The dried cell powders were analyzed for the quality aspects (morphology, flowability, and storage stability). The best results were observed, with a combination of whey protein and corn starch (cell survival: 82.37% and yield: 56%, w/w) with a shelf life of 6 months (with only 10% reduction in cell survival). The survival was found to be 40% without any carrier material, which decreased to less than 25% within 4 weeks.     

Surface topography of polylactic acid nanofibrous mats: influence on blood compatibility

Fabricating nanofibrous scaffolds with robust blood compatibility remains an unmet challenge for cardiovascular applications since anti-thrombogenic surface coatings did not withstand physiological shear force. Hence, the present study envisages the influence of smooth and porous topographies of poly(lactic acid) (PLA) nanofibers on hemocompatibility as it could offer time-independent blood compatibility. Further, recent studies have evolved to integrate various contrasting agents for augmenting the prognostic properties of tissue engineered scaffolds; an attempt was also made to synthesize Curcumin–superparamagnetic iron oxide nanoparticle complex (Cur–SPION) as a contrasting agent and impregnated into PLA nanofibers for evaluating the blood compatibility. Herein, electrospun nanofibers of PLA with different topographies (smooth and porous) were fabricated and characterized for surface morphology, zeta potential, fluorescence, and crystallinity. The scaffolds with smooth, porous and rough surface topographies were thoroughly investigated for its hemocompatibility by evaluating hemolysis percentage, platelet adhesion, in vitro kinetic clotting time, serum protein adsorption, plasma recalcification time (PRT), capture and release of erythrocytes. Although the nanofibers of all three groups showed acceptable hemolytic percentage (HP?<?5%), the adhered RBCs on Cur–SPION based fibers undergo morphological transformation from biconcave discocytes to echinocytes with cube-like protrusions. On the contrary, no morphological changes were observed in RBCs cultured on smooth and porous nanofibers. Porous fibers exhibited excellent anti-thrombogenic property and adhered lesser platelets and maintained the discoidal morphology of native platelets. Cur–SPION integrated PLA nanofibers showed inactivated platelets with anti-thrombogenic activity compared to smooth nanofibers. In conclusion, PLA nanofibers porous topography did not affect the RBC membrane integrity and maintained discoidal morphology of platelets with superior anti-thrombogenic activity. However, smooth and Cur–SPION integrated PLA nanofibers were found to activate the platelets and deform the RBC membrane integrity, respectively. Hence, the nanofibers with porous structures provide an ideal topography for time-independent hemocompatibility.

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Encapsulation of yeast (Saccharomyces cereviciae) by spray drying for extension of shelf life

The objective of the present work was to encapsulate yeast using different carrier materials and examine their efficacy in retaining viability of cells after spray drying. Slurry containing yeast cells along with known amount of carrier material (maltodextrin, corn starch, gum arabic, acacia gum, polyethylene glycol 8000, β-cyclodextrin, and skimmed milk powder, one at a time) was added and served as feed. Among these carrier materials attempted, corn starch and maltodextrin showed the best results with respect to powder yield (59%, w/w) and cell survival (80.5%), respectively. However, considering both survival and powder yield (67 and 59% w/w, respectively), corn starch was observed to be the most suitable carrier material.     

Optical and thermal characterization of albumin protein solders

The effect of temperature on the optical and thermal properties of pure and indocyanine green-doped albumin protein solders as a function of wavelength has been studied between 25 degrees C and 100 degrees C. An increase in the group refractive index by up to 4% and a decrease in absorption coefficient (approximately 800 nm) by up to 8%, after denaturing the solder specimens in a constant-temperature water bath at temperatures of 60-100 degrees C, were not significant. The reduced scattering coefficient, however, increased rapidly with temperature as the solder changed from being a highly nonscattering medium at room temperature to a highly scattering medium at temperatures close to 70 degrees C. The thermal conductivity, thermal diffusivity, and heat capacity increased by up to 30%, 15%, and 10%, respectively. Finally, the frequency factor and activation energy were measured to be 3.17 x 10(56) s(-1) and 3.79 x 10(5) J mol(-1), respectively, for liquid protein solders (25% bovine serum albumin) and 3.50 x 10(57) s(-1) and 3.85 x 10(5) J mol(-1), respectively, for solid protein solders (60% bovine serum albumin). Incorporation of dynamic optical and thermal properties into modeling studies of laser tissue interactions could have a significant influence on the determination of the expected zone of damage.     

Effect of composition on the conductivity and morphology of ligno sulfonic acid sodium salt doped polyaniline

A systematic approach is developed to study the ligno sulfonic acid sodium salt (LSA) protonation or doping process with polyaniline emeraldine base (Pani‐EB) in organic solvents like dimethyl sulfoxide, and the influence of LSA‐doping on the properties of polyaniline was investigated in detail. The composition of Pani‐EB and LSA was varied in the weight ratio of 1:1 to 1:50 to investigate the effect of the dopant concentration on the conductivity and morphology. The doping process was confirmed by UV–vis and FTIR spectroscopes. The composition analysis indicates that only 50% of the LSA is used for the doping process irrespective of the weight ratio of LSA/Pani‐EB in the feed. The four probe conductivity measurement suggests that the conductivity of the doped samples are increasing with the increase in the ratio of Pani‐EB/dopant composition, and the high conductivity of the doped material was obtained in the range of 1.0 × 10^?2 S/cm. Scanning electron microscopy reveals that LSA induces a selective aggregation in the polyaniline chains to produce needlelike or rod‐shape morphology of sizes having ～0.2 μm diameter and 1 μm length. At very higher amount of LSA, the microrods are completely collapsed and form uniform continuous morphology. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2650–2655, 2006     

<Emphasis Type="Italic">cis</Emphasis>-, <Emphasis Type="Italic">trans</Emphasis>- and Saturated Fatty Acids in Selected Hydrogenated and Refined Vegetable Oils in the Indian Market

The fatty acid composition of 27 samples of commercial hydrogenated vegetable oils and 23 samples of refined oils such as sunflower oil, rice bran oil, soybean oil and RBD palmolein marketed in India were analyzed. Total cis, trans unsaturated fatty acids (TFA) and saturated fatty acids (SFA) were determined. Out of the 27 hydrogenated fats, 11 % had TFA about 1 % where as 11 % had more than 5 % TFA with an average value of about 13.1 %. The 18:1 trans isomers, elaidic acid was the major trans contributor found to have an average value of about 10.8 % among the fats. The unsaturated fatty acids like cis-oleic acid, linoleic acid and α-linolenic acid were in the range of 21.8–40.2, 1.9–12.2, 0.0–0.7 % respectively. Out of the samples, eight fats had fatty acid profiles of low TFA (less than 10 %) and high polyunsaturated fatty acids (PUFA) such as linoleic and α-linolenic acid. They had a maximum TFA content of 7.3 % and PUFA of 11.7 %. Among the samples of refined oils, rice bran oil (5.8 %) and sunflower oil (4.4 %) had the maximum TFA content. RBD palmolein and rice bran oils had maximum saturated fatty acids content of 45.1 and 24.4 % respectively. RBD palmolein had a high monounsaturated fatty acids (MUFA) content of about 43.4 %, sunflower oil had a high linoleic acid content of about 56.1 % and soybean oil had a high α-linolenic acid content of about 5.3 %.