Lipid lowering therapy and military aviators

This article discusses the role of the newer lipid lowering agents (statins and fibrates) for the treatment of hyperlipidemias in military aviators. Special emphasis will be on long-term safety and the effects of these drugs on CNS functions pertinent to aviators. We propose that these new lipid lowering agents, such as hydrophilic statins and newer fibrates are reasonably safe in aviators with restricted flying duties, subject to long-term surveillance by a specialist.     

System partitioning of MCMs for low power

Meeting the design challenges inherent in complex multichip modules that also reduce power dissipation is a daunting task, considering the number of constraints and the nonlinear cost functions explored early in the prototyping process. Current algorithms do not do the job. A new systematic approach combines commercial software with simple size-reduction and linearization methods that are largely unknown in the industry. The authors present results obtained from experiments with a set of large ICs     

Immobilization of Dicationic Mn(III) Salen in the Interlayers of Montmorillonite Clay for Enantioselective Epoxidation of Nonfunctionalized Alkenes

Dicationic chiral Mn(III) salen complex (0.4 mol%) immobilized in the interlayer of montmorillonite clay 4A, epoxidize bulkier alkenes (epoxide yield 68–99%) with high chiral induction (up to 95% ee) with a catalyst reusability of up to four cycles.     

Synthesis and evaluation of morpholinoalkyl ester prodrugs of indomethacin and naproxen

Morpholinoalkyl esters (HCl salts) of naproxen 1 and indomethacin 3 were synthesized and evaluated in vitro and in vivo for their potential use as prodrugs for oral delivery. Prodrugs were freely soluble in simulated gastric fluid (SGF) and pH 7.4 phosphate buffer and showed a minimum of a 2000-fold increase in solubility over the parent drugs. All prodrugs were more lipophilic than parent drugs as indicated by n-octanol/pH 7.4 buffer partition coefficients but less lipophilic in terms of n-octanol/SGF partition coefficients. Potentiometrically determined pKa's for prodrugs were in the range of 6.89 to 8.62 at 25 degrees C. All prodrugs were quantitatively hydrolyzed to their respective parent drugs by enzymatic and/or by chemical means. An increase in carbon chain length rendered the prodrugs more stable at pH 7.4 but less stable in SGF. The esters were generally found to be hydrolyzed rapidly in rat plasma at 37 degrees C, the half-lives being in the range of 1.2-31.0 min. Based on in vitro results, prodrugs 2c and 4c were chosen to evaluate solid-state stability, in vivo bioavailability, and ulcerogenicity. At elevated temperatures, the solid-state decomposition of 2c and 4c followed biphasic kinetics, with rapid decomposition occurring initially. The prodrugs were 30-36% more bioavailable orally than the parent drugs following a single equimolar solution dose in rats. Prodrugs 2c and 4c were significantly less irritating to gastric mucosa than parent drugs following single-dose and chronic oral administration in rats.     

Formulation of electric-field integral equation without use of differential operator

We derive a new formulation of the electric-field integral equation for the surface current density on an infinitely long conducting strip, with a TE incident field. The formulation avoids the use of a differential operator, allows numerical solution using pulse basis functions and point matching, and is applicable to any two-dimensional scatterer. Our approach is readily extendable to three-dimensional problems.     

Fluorescent lipids of bovine brain white matter

Two fluorescent lipids were isolated from a chloroform-methanol (2∶1 v/v) extract of bovine brain white matter by two-step preparative thin layer chromatography on Silica Gel G. The first step was performed with chloroform-diethyl ether-acetic acid (70∶30∶1 v/v) as developing solvent and revealed a single fluorescent band below the solvent front. The band was scraped off, and the lipid was eluted in chloroform and reapplied to Silica Gel G plates. In the second step, benzene-methanol-ethyl acetate (85∶10∶5 v/v) as developing solvent revealed two fluoresent bands (A and B) with R_f values of 0.72 and 0.65. The lipids were eluted and the UV and visible absorption spectra were measured in heptane, as were the excitation and fluorescence spectra. Sulfuric acid absorption spectra (2 and 24 hr treatment at 22 C) as well as the resulting excitation and fluorescence spectra were also determined. The fluorescent lipids reacted positively in a number of nonspecific color tests for steroids, but the chemical nature of these minor components of the neutral lipid fraction remains to be established.     

Methane oxidative coupling over bismuth oxychloride-lithium carbonate-magnesia systems

The conversion of methane, the selectivity to C₂ hydrocarbons, and, particularly, the ethene-to-ethane ratio are much higher over BiOCl-Li₂CO₃-MgO than those over pure BiOCl and BiOCl-MgO. In addition, they remain almost the same over a period of 5 h for the former system, but decline significantly for the other two systems (BiOCl and 10% BiOCl-MgO). The XPS investigations provide some insight about the processes responsible for this behavior, indicating that not only Cl but also Bi is likely to play a role.     

A lapping and polishing process to achieve high quality alumina surfaces for applications in device fabrication

A lapping process for achieving high quality alumina (Al₂O₃) surfaces was investigated. Alumina films were sputter deposited on thick TiC---Al₂O₃ ceramic wafers. Polishing of these films was carried out on pitch plates (organic resin melted and set on the circular disk of a lapping machine). Abrasives with different grit sizes, 0.05–1.0 μm, were tried together with different lapping process parameters. Qualitu of the lapped surface was studied in terms of roughness and flatness. Stock removal rates were also measured. Correlation of surface quality with lapping parameters was established to achieve process optimization.

Scratch-free polished alumina surfaces were obtained by using this technique. Specific applications of the process in the fabrication of magnetic recording devices are indicated.     

Dissociation constants of long chain fatty acids in methanol-water and ethanol-water mixtures

The pK_a values of lauric acid, myristic acid, palmitic acid and stearic acid in methanol-water and ethanol-water mixtures of different compositions at 303 K and ionic strength, I=0.1M(KNO₃) have been determined. The pK_a values of the fatty acids have been found to increase with the alcohol content of the solvent. It has also been found that, in general, the pK_a values in the ethanolic solvent are greater than those in the methanolic solvent. In a given solvent mixture the observed pK_a value decreases in the order of stearic acid > palmitic acid > myristic acid > lauric acid. Departure from the predicted linearity of the plots of pK_a against the inverse of the dielectric constant, 1/D indicates that the electrostatic effects taken into account by the Born theory are not adequate enough to represent the total medium effects on pK_a.