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The recent developments in electric vehicle (EV) necessities the requirement of a human intervention free charging system for safe and reliable operation. Wireless power transfer (WPT) technology shows promising options to automate the charging process with user convenience. However, the operation of the WPT system is designed to operate at a high-frequency (HF) range, which requires proper control and modulation technique to improve the performance of power electronic modules. This paper proposes a dead-time (DT) integrated Pulse Density Modulation (PDM) technique to provide better control with minimal voltage and current ripples at the switches. The proposed technique is investigated using a LCC-LCL compensated WPT system, which predominantly affects the high-frequency voltage and current ripples. The performance analysis is studied at different density conditions to explore the impact of the integrated PDM approach. Moreover, the PDM technique gives better control over the power transfer at different levels of load requirement. The simulation and experimental analysis was performed for a 3.7 kW WPT prototype test system under different modes of operation of the high-frequency power converters. Both the simulated and experimental results demonstrate that the proposed PDM technique effectively enhances the efficiency of the HF inverter while significantly reducing output current ripples, power dissipation and improving the overall WPT system efficiency to 92%, and leading to a reduction in the power loss in the range of 10% to 20%. This leads to improved overall system control and performance. [ABSTRACT FROM AUTHOR]

Tetraphenylporphyrin conjugates with one (PB1) and four (PB4) cobalt(III) bis(1,2-dicarbollide) substituents are synthesized and the physicochemical and photophysical properties are described. It is found that both PB1 and PB4 are new representatives of nonpeptide HIV-I protease inhibitors.

Enhanced hydrolysis rates for the cleavage of bis(4-nitrophenyl)phosphate (BNPP), a modelphosphodiester, can be achieved by using ditopic receptors containing the known phosphate-binding nucleus, sapphyrin, attached covalently to suitably oriented polyhydroxyl subunits. The results suggest that the presence of ditopic approach is useful in the construction of catalysts capable of enhancing the hydrolysis of other less-active phosphodiester substrates including oligonucleotides.

HIV protease (PR) represents a prime target for rational drug design, and protease inhibitors (PI) are powerful antiviral drugs. Most of the current PIs are pseudopeptide compounds with limited bioavailability and stability, and their use is compromised by high costs, side effects, and development of resistant strains. In our search for novel PI structures, we have identified a group of inorganic compounds, icosahedral metallacarboranes, as candidates for a novel class of nonpeptidic PIs. Here, we report the potent, specific, and selective competitive inhibition of HIV PR by substituted metallacarboranes. The most active compound, sodium hydrogen butylimino bis-8,8-[5-(3-oxa-pentoxy)-3-cobalt bis(1,2dicarbollide)]di-ate, exhibited a [K.sub.i] value of 2.2 nM and a submicromolar E[C.sub.50] in antiviral tests, showed no toxicity in tissue culture, weakly inhibited human cathepsin D and pepsin, and was inactive against trypsin, papain, and amylase. The structure of the parent cobalt bis(1,2-dicarbollide) in complex with HIV PR was determined at 2.15 [Angstrom] resolution by protein crystallography and represents the first carborane-protein complex structure determined. It shows the following mode of PR inhibition: two molecules of the parent compound bind to the hydrophobic pockets in the flap-proximal region of the S3 and S3' subsites of PR. We suggest, therefore, that these compounds block flap closure in addition to filling the corresponding binding pockets as conventional PIs. This type of binding and inhibition, chemical and biological stability, low toxicity, and the possibility to introduce various modifications make boron clusters attractive pharmacophores for potent and specific enzyme inhibition. rational drug design | aspartic proteases | carboranes | x-ray structure analysis | virostatics

Eight meso-aryl calixphyrin derivatives are synthesized and their conformational equilibria and transitions studied with temperature-dependent NMR spectroscopy. Based on density functional computations, several conformer species could be identified and observed changes in chemical shifts explained.

A convenient route to functionalized porphomono-and prophodimethenes in up to 41% yield is reported. It is found that tuning of experimental conditions dramatically influences distributions of the products.

The selection of substituents of the porphyrin macrocycle allows to preprogram the behavior of the porphyrins in aqueous solutions. It was demonstrated that the stacking interaction between porphyrin units and the hydrophobic interactions between alkyl/aryl residues of the phosphonium moieties and the porphyrin macrocycles stabilize the aggregated forms.

Polyvinyl chloride-derived ion-selective electrodes (ISEs) were produced from a neutral anion binding receptor, meso-octamethylcalix(4)pyrrole (1). Analogous systems were also produced from the novel pyridine-containing analogues of 1, namely dichlorocalix(2)pyrrole(2)pyridine (2) and tetrachlorocalix(4)pyridine (3). Results showed that the potentiometric selectivity for membrane ISEs based on 2 and 3 toward a range of investigated anions was found to be pH dependent.