Thermo-neutral production of metals and hydrogen or methanol by the combined reduction of the oxides of zinc or iron with partial oxidation of hydrocarbons

Stoichiometry and temperature requirements are determined for combining the endothermic reduction of metal oxides (ZnO, Fe₂O₃, and MgO) with the exothermic partial oxidation of hydrocarbons (CH₄, n-butane, n-octane, and n-dodecane) in order to co-produce simultaneously metals and syngas in thermo-neutral reactions. Thermogravimetric and GC measurements on the combined reduction of ZnO and Fe₂O₃ with the partial oxidation of CH₄ were conducted at 1400 K to experimentally verify the products predicted by equilibrium computations, and resulted in the complete reduction to Zn and Fe, respectively, while producing high quality syngas. A preliminary economic assessment that assumes a natural gas price of 11.9 US$/MWh and credit for zinc sale at 750 US$/metric ton, indicates a competitive cost of hydrogen production at 6.0 US$/MWh, based on its high heating value. The proposed combined process offers the possibility of co-producing metals and syngas in autothermal non-catalytic reactors, with significant avoidance of CO₂ emission.     

Characterization of glycopeptide-resistant enterococci from a Swiss hospital

Between August 1994 and September 1996, 28 glycopeptide-resistant enterococci (GRE) were isolated from 8 infected patients and 11 intestinal carriers hospitalized at the University Hospital of Geneva. Identification to the species was made by both phenotypic (API 20 STREP and Rapid ID 32 STREP systems, and Vitek Gram Positive Identification Card) and genotypic methods using a multiplex PCR assay developed also for the determination of the genotype of glycopeptide resistance (vanA, vanB, vanC1, and vanC2-C3 genes). Fifteen isolates were identified as Enterococcus faecium, 8 as E. gallinarum, 4 as E. faecalis, and 1 as E. hirae. All of the phenotypic identification methods failed to differentiate some isolates of E. gallinarum from E. faecium, or vice versa. Both vanA (n = 18) and vanB (n = 4) glycopeptide resistance genotypes were found. For the first time, the vanB determinant was found in two isolates of E. gallinarum. Two patients were colonized by two different species containing the vanA gene and one by two different species containing the vanB gene. All vanA isolates were highly resistant to both vancomycin and teicoplanin except for three isolates which were susceptible to teicoplanin. Molecular typing by pulsed-field gel electrophoresis showed identical or similar patterns among E. faecium isolates with the vanA gene in five patients for whom the epidemiological link could not be always elucidated. This study emphasizes the necessity of utilizing both phenotypic and genotypic methods to characterize GRE.     

Colorectal intussusception: an unusual gastrointestinal complication of hereditary angioedema

One case of prenatally diagnosed congenital diaphragmatic hernia was reviewed in terms of the anesthetic managements. Concentrations of diazepam, pancuronium and fentanyl were measured in maternal, fetal and umbilical serum. As expectedly, the transition of diazepam through the placenta was large and the concentration of diazepam in the fetal serum was equal to that of maternal serum, but only a small amount of pancuronium was transferred.     

Rate-Distortion Coding Simulation for Color Images

We propose a distortion measure for color images, based on a mathematical model of color vision, and supported by subjective image quality evaluations. The visual model is configured after a simplified schematic of the retina's physiology and it transforms the red, green and blue image components into a representation that is consistent with major psychophysical phenomena. The distortion criterion proposed consists of measuring the mean square error in the above representation space. Consistency of the measure with human quality judgment is supported by a subjective ranking experiment, using images distorted in various ways by addition of noise. An optimal coder (in the rate distortion sense) is also simulated, which minimizes the distortion measured as proposed. The resulting image provides a quality standard at the rate distortion bound, against which actual coders can be compared. Finally it is observed that from a statistical point of view, the model's output is a near ideal color image representation for efficient coding.     

Diffuse Reflectance Spectroscopy; Applications,Standards, and Calibration (With Special Reference to Chromatography)

The multitude of areas in which diffuse reflectance spectroscopy can be applied has been described in several books and reviews and ranges from color measurements of textiles, pharmaceuticals, building materials, paper and pulp materials etc., to adsorption studies and other basic investigations in physical, inorganic and organic chemistry.The major area of application is still the measurement of color which has become indispensible in the quality control of colored products, dyes and pigments. Color matching practices and techniques with sophisticated instrumentation which can be fully computerized as well as the use of simpler filter instruments for quality control are mentioned.Transferability of reflectance data i.e., color coordinates, depends on the quality of standards particularly when absolute measurements are desired. The difficulty of finding suitable “white standards” with good reflection properties at low UV and with a good long term stability is discussed. Similar arguments hold for sphere coating materials. For the measurement of fluorescing surfaces suitable standards are lacking which renders transfer of such data almost impossible.The usefulness of diffuse reflectance techniques to study adsorption phenomena on small particle adsorbents is demonstrated with a malachite green-o-carboxylic acid lactone system studied by Kortüm. This or similar systems could be adopted to the measurement of relative surface areas on certain chromatographic adsorbents yielding more realistic values than the BET-method.The most recent area of application has been in the field of chromatography for the in situ evaluation of chromatographic zones in flat-bed chromatography, electrophoresis and isoelectric focusing.In chromatography, standardization is less problematic since usually relative measurements are sufficient. On the other hand one has to find suitable calibration procedures. The use of the Kubelka-Munk function is often questionable since we are usually not dealing with layers of infinite thickness and below 300 nm the conventional adsorbents such as silica gel, alumina or cellulose are strongly absorbing. Experiences with a new function combining the laws of Kubelka-Munk and Lambert-Beer are therefore presented.The problem is also to find calibration techniques which account for chromatographic parameters. Until recently it was believed that a quantitative evaluation of chromatograms required a number of reference zones to be developed on the same chromatogram. In our experience this is no longer true. A novel calibration technique which utilizes the concept of transferable calibration factors is discussed. With this approach a quantitative evaluation of a chromatogram with only one reference spot is possible. Here again scanning and data acquisition can be fully automated. The application of proper calibration procedures to differential reflectance techniques and the measurement of multi-component systems is briefly mentioned.Finally it is demonstrated that it is possible to carry out in situ quantitative measurements on low UV absorbing compounds (down to 190 nm) separated on silica gel surfaces, provided suitable techniques and instrumentation are used.     

Unusual intestinal manifestations of tuberculosis

In an 87-year-old Swiss female referred with complaints of bloody diarrhea and weight loss, colonoscopy revealed three ulcers in the rectum and colon. Cultures from the colonic ulcers were positive for Mycobacterium tuberculosis. There was no evidence of pulmonary infection. One week after adequate therapy was begun, a perforation occurred at the rectosigmoid junction. The sigmoid was resected and left-sided colostomy was performed. Seven days after surgery the patient died. Clinical features, diagnosis and morphological changes of intestinal tuberculosis are discussed.     

Dose escalation of the hypoxic cell sensitizer etanidazole combined with ifosfamide, carboplatin, etoposide, and autologous hematopoietic stem cell support

Multiple mechanisms of drug resistance contribute to treatment failure. Although high-dose therapy attempts to overwhelm these defenses pharmacologically, this approach is only successful in a fraction of treated patients. Many drug resistance mechanisms are shared between malignant and normal cells, but the expression of various drug resistance mechanisms associated with hypoxia is largely confined to tumor tissue. Thus, reversal of this mechanism is likely to provide a therapeutic advantage to the host. This study was designed to define the dose-limiting toxicities and maximum tolerated dose of etanidazole when it is given concurrently with high-dose ifosfamide, carboplatin, and etoposide (ICE), with hematopoietic stem cell support. The maximum tolerated doses of high-dose ICE were administered concurrently with dose escalations of etanidazole, a hypoxic cell sensitizer. All agents were given by 96-h continuous i.v. infusion beginning on day -7. Mesna uroprotection was provided. Autologous marrow and cytokine mobilized peripheral blood progenitor cells were reinfused on day 0. Granulocyte colony-stimulating factor was administered following reinfusion until the granulocytes recovered to > 1000/microliter. Fifty-five adults with advanced malignancies were enrolled in cohorts of five to nine patients. Four dose levels of etanidazole between 3 and 5.5 g/m2/day (12, 16, 20, and 22 g/m2 total doses) and two doses of carboplatin (1600 and 1800 mg/m2 total doses) were evaluated. Seven patients died of organ toxicity (13%); two each from veno-occlusive disease of liver and sepsis; and one each from sudden death, renal failure, and refractory thrombocytopenic hemorrhage. Five deaths occurred at the top dose level. One additional patient suffered a witnessed cardiorespiratory arrest from ventricular fibrillation and was resuscitated. Dose-dependent and largely reversible peripheral neuropathy was observed consisting of two syndromes: severe cramping myalgic/neuralgic pain, predominantly in stocking glove distribution, occurring between day -3 and day 0, and a sensory peripheral neuropathy with similar distribution peaking around day +60. The maximal achievable dose of etanidazole (16 g/m2 dose level) resulted in a mean serum level of 38 micrograms/ml (25-55 micrograms/ml). Etanidazole significantly enhanced host toxicity of high-dose ICE. Effective modulatory doses of etanidazole could not be given with acceptable toxicity using this schedule.     

Oligosaccharide mimics containing galactose and fucose specifically label tumour cell surfaces and inhibit cell adhesion to fibronectin

With the aim of establishing a versatile and easy synthesis of branched saccharides for biological applications, we used molecular-dynamics simulations to model Lewis(y) to two classes of di- or triantennary saccharide mimetics. One set of mimetics was based on 1,3,5-tris(hydroxymethyl)cyclohexane (TMC) as the core, the other on furan, and both were derivatised with galactose and/or fucose. The TMC-based saccharides were biotinylated, while the furan disaccharides were treated with maleimide-activated biotin in a Diels-Alder fashion to yield oxazatricyclodecanes (OTDs). These were then assayed as cell-surface labels in human colon (SW480 and CaCo-2), liver (PLC), Glia (U333 CG 343) and ovary (SKOV-3) tumour cell lines. Discrete staining patterns were observed in all cells, usually at one or two poles of the cells, particularly with the asymmetric 3-beta-L-fucopyranosyloxymethyl-4-beta-D-galactopyranosyloxymethyl-OTD. Normal SV40-transformed fibroblasts (SV80) showed no staining. Adhesion of the highly metastatic mouse melanoma line B16 F10 to fibronectin was inhibited by 80 % by the TMC-digalactoside and by 30 % by 3,4-bis-(beta-D-galactopyranosyloxymethyl)furan. None of the saccharide mimetics inhibited the adhesion of the less metastatic B16 F1 line. Migration of B16 F10 cells through Matrigel was greatly inhibited by the TMC-digalactoside and weakly inhibited by the TMC-trigalactoside. The saccharide mimetics that had shown the best structural agreements with the terminal saccharides of Lewis(y) in the molecular dynamics simulation were also the most biologically potent compounds; this underlines the predictive nature of molecular dynamics simulations. The use of the non-saccharide cores enabled us to adapt spacer lengths and terminal saccharides to optimise the structures to bind more avidly to cell-surface lectins.