Experience with ERCOT System's IT development and operation

ERCOT is an independent, not for profit organization that manages the deregulated electric system in the state of Texas. The deregulation model includes separate markets for bulk power and retail choice, with ERCOT acting as a facilitator for ancillary service market operation, reliability coordination and retail switching. The information technology (IT) tools are broadly classified under three categories-technical operations, commercial operations, and data warehouse. Technical operations include the market operation system (MOS) working in tandem with the power operation system (POS). Commercial operations include the client registration, load profiling, data acquisition, data aggregation, settlements, billing and a transaction clearing house. Since the ERCOT market is an evolving market, new market rules and reliability standards are established periodically and the IT tools are updated to reflect these changes. This paper provides an overview of the development and operational process of the IT tools pertaining to the ERCOT technical operations system.     

COMPARISON OF NASAL INSULIN POWDERS PREPARED BY SUPERCRITICAL FLUID AND FREEZE-DRYING TECHNIQUES

In this study, the effect of drug loading on the nasal absorption of insulin was determined. Human insulin was loaded into different drug carriers by two methods: supercritical fluid processing and freeze-drying. The powder formulations were characterized and then evaluated after nasal administration to alloxan induced diabetic rabbits at a dose of 5U/kg and 7.5U/kg. The blood glucose levels and serum insulin levels were monitored for five hours after administration of insulin formulations. The drug carriers evaluated were: ammonium glycyrrhizinate (AG), polyacrylic acid (PAA), cross-linked polyacrylic acid (CPAA), polyethylene oxide (PEO) and chitosan (CHTN).

Nasal administration of AG infused with insulin by carbon dioxide resulted in absolute bioavailability of 9.81% as compared to 2.86% observed with same powder loaded with insulin by freeze-drying. 8.05% bioavailability was obtained with PAA powder loaded with insulin by carbon dioxide as compared to much lower absorption seen with freeze-dried formulation. Similarly a two fold increase in absolute bioavailability was observed when carbon dioxide infused CPAA powder formulation was compared to the lyophilized powder. Nasal administration of PEO and CHTN loaded with insulin by carbon dioxide resulted in bioavailabilities of 1.55% and 1. 18% respectively.

The drug-loading process seems to have a significant effect on nasal absorption of insulin. The powders loaded with insulin by carbon dioxide infusion resulted in significantly higher absorption. The exact mechanism is still not known and a possible explanation for increased absorption may be due to improved stability of insulin in carbon dioxide infused formulations. Among the powders evaluated, polyacrylic acid and ammonium glycyrrhizinate prepared by carbon dioxide infusion as drug-loading method seem to offer good potential for development of nasal powder dosage forms for insulin.     

On the Trapping of Vinylgold Intermediates

An internal aryl‐substituted ortho‐alkynylphenol and a similar aniline with stoichiometric amounts of N,N′‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene‐gold tosylate [(IPr)AuOTs] and triethylamine gave the aurated heterocycles as stable intermediates of the corresponding gold(I)‐catalysed hydrooxylation and hydroamination reactions. X‐ray crystal structure analyses of both products could be obtained. A similar internal alkyl‐substituted ortho‐alkynylphenol gave only the cycloisomerised product, no aurated intermediate could be detected.     

A new power sensitivity method of ranking branch outagecontingencies for voltage collapse

The objective of this paper is to present a powerful procedure for identifying severe single branch outage contingencies with respect to saddle-mode bifurcation induced voltage collapse, given a power system operating point, a load demand forecast, and a generation dispatch. The new power sensitivity ranking algorithm for voltage collapse, called λ/MVA sensitivity, provides more accurate "distance to collapse" estimates than linear admittance sensitivity, yet requires only slightly more computation time. The distinguishing features are the ability (1) to rank all branches in a large-scale power system quickly, and (2) to estimate the outage contingency bifurcation values accurately. As an illustration, the new λ/MVA sensitivity ranking algorithm can estimate all 6689 single branch outage contingency bifurcation points (λ*_ctgc) of a 3493 bus power system within 3% relative error, except for two branches within 7%, in less than 4 min on a 180 MHz PentiumPro PC