High purity H2 by sorption-enhanced chemical looping reforming of waste cooking oil in a packed bed reactor.

High purity hydrogen (>95%) was produced at 600 degrees C and 1 atm by steam reforming of waste cooking oil at a molar steam to carbon ratio of 4 using chemical looping, a process that features redox cycles of a Ni catalyst with the in-situ carbonation/calcination of a CO(2) sorbent (dolomite) in a packed bed reactor under alternated feedstreams of fuel-steam and air. The fuel and steam conversion were higher with the sorbent present than without it. Initially, the dolomite carbonation was very efficient (100%), and 98% purity hydrogen was produced, but the carbonation decreased to around 56% with a purity of 95% respectively in the following cycles. Reduction of the nickel catalyst occurred alongside steam reforming, water gas shift and carbonation, with H(2) produced continuously under fuel-steam feeds. Catalyst and CO(2)-sorbent regeneration was observed, and long periods of autothermal operation within each cycle were demonstrated.

Chemical looping reforming of waste cooking oil in packed bed reactor.

Chemical looping steam reforming for hydrogen production from waste cooking oil was investigated using a packed bed reactor. The steam to carbon ratio of 4 and temperatures between 600 and 700 degrees C yielded the best results of the range of conditions tested. Six cycles at two weighted hourly space velocities (WHSV of 2.64 and 5.28 h(-1)) yielded high (>0.74) and low (<0.2) oil conversion fractions, respectively, representing low and high coking conditions. The WHSV of 2.64 h(-1) yielded product concentrations closest to equilibrium values calculated assuming a fresh rapeseed oil composition. Repeated cycling revealed some output oscillations in reactant conversion and in the extent of Ni-NiO conversion, but did not exhibit deterioration by the 6th cycle. The selectivity of CO, CO(2) and CH(4) were remarkably constant over the performed cycles, resulting in a repeatable syngas composition with H(2) selectivity very close to the optimum.

Effects of the glucocorticoid agonist, RU28362, and the antagonist RU486 on lung phosphatidylcholine and antioxidant enzyme development in the genetically obese Zucker rat.

The biochemical maturation of the lung in late gestation and in the young animal is regulated by glucocorticoids. The present study was aimed at dissociating the different glucocorticoid receptor sites involved in these regulatory functions. The obese Zucker rat was selected as a model for this study as it exhibits hypersensitivity to glucocorticoid hormone action by virtue of its elevated receptor numbers and activity. Two synthetic steroid analogues were administered to obese animals; RU28362, a specific type II receptor agonist, and the type II antagonist RU486. RU28362 promoted a strong catabolic effect, which was associated with reduced food intake and the abolition of growth in the rats. The agonist, RU28362, attenuated developmental increases in antioxidant enzyme activities, and altered the growth of the tissue. At the age studied, development of the lung phosphatidylcholine (PC) system was almost complete, but RU28362 increased disaturated PC 16:0/16:0 concentrations by almost 2-fold, and altered the molecular composition of total pulmonary PC. RU486 attenuated the growth of the rats and reduced their food intake. Treatment with the type II antagonist attenuated lung growth and increased the activities of pulmonary copper zinc (Cu/Zn) and manganese (Mn) superoxide dismutases. RU486 had no effect on lung PC concentrations and molecular composition. The data suggest a role for type I glucocorticoid receptors in the regulation of the antioxidant enzyme system in the lung, as type II antagonism will channel endogenous glucocorticoid binding to the type I site. Type II receptor binding would appear to play a role in regulating the lung PC content.

Magnitude of hyperoxic stress and degree of lung maturity determine the nature of pulmonary antioxidant response in the guinea pig.

The ability of the immature lung to induce antioxidant defences in response to hyperoxic stress was examined. Preterm guinea pigs (65 days gestation, term = 68 d) were exposed to either 21% O2, 85% O2 or 95% O2 for 72 hours. Exposure to 85% O2 increased lung catalase, glutathione peroxidase and manganese superoxide dismutase activities in comparison to air controls. Exposure to 95% O2 resulted only in an increase in glutathione peroxidase activity. Bronchoalveolar lavage fluid GSH concentration was increased by a similar amount by both exposure regimes, while lung copper/zinc superoxide dismutase activity was unchanged by either treatment. Comparison of the antioxidant response of term and preterm animals exposed to 85% O2 for 72 hours indicated a greater response in the lung of the preterm animals. Manganese superoxide dismutase activity was elevated in both term and preterm animals, while catalase and glutathione peroxidase activities were elevated only in preterm animals. The extent of microvascular permeability as indicated by bronchoalveolar lavage fluid protein concentration, was lower in preterm animals than in term animals. We conclude that the immature lung can respond to hyperoxic stress by antioxidant induction and that the nature of the response is dependent, in part, both on the severity of the stress and on the maturity of the lung.

HIV-1 proteinase is required for synthesis of pro-viral DNA.

HIV-1 proteinase activity is thought to occur primarily post-integration by cleaving the viral Gag and Gag-Pol polyproteins. Its role in the pre-integration stages of viral replication, however, has not been studied in detail. Here we report that a synthetic peptide analogue, UK-88,947, which is a specific inhibitor of purified HIV-1 proteinase, inhibits the processing of the viral polyproteins in cultures of HIV-1 infected cells and prevents the formation of mature, infectious virions. Analysis of DNA from HIV-1 infected cells treated with UK-88,947 showed that viral DNA synthesis was inhibited when the compound was added to cultures one hour before infection. Similar results were obtained when AZT was used. Neither HIV-1 reverse transcriptase or the replication of FIV are inhibited by UK-88,947.

Biochemical maturation of the guinea pig lung and survival following premature delivery.

1. Viable preterm guinea pigs were delivered by Caesarean section from 62 day gestation (term = 68 days). 2. Survival rates (24 hr) were greater than 90%, greater than 55% and greater than 35% respectively at 65, 63 and 62 days gestation. Guinea pig pups experienced increasing respiratory difficulty with progressive prematurity. 3. Lung phosphatidylcholine concentration increased steadily from 0.52 +/- 0.09 mumol/mg DNA at day 50 to 3.9 +/- 0.5 mumol/mg DNA at term. The relative contribution of the disaturated dipalmitoyl species increased over this time from 24.5 to 42.9%. 4. Pulmonary antioxidant capacity increased markedly over the final eight days of gestation, individual increases being manganese superoxide dismutase 68%, copper/zinc superoxide dismutase 48%, glutathione peroxide 37% and catalase 198%.

Developmental expression of antioxidant enzymes in guinea pig lung and liver.

Antioxidant enzyme activities, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and total glutathione concentration were determined in guinea pig lung and liver over the final period of gestation (days 50-68) and at several ages post-partum. Pulmonary antioxidant capacity increased markedly over the final days of gestation, individual changes ranging from 29% (glutathione) to 198% (GSH-Px). Liver antioxidant capacity was always 4-fold to 10-fold greater than that of the lung and exhibited very similar developmental profiles to those observed in the lung. From day 60 gestation to term (68 days), activity of the liver antioxidants increased, ranging from 246% (CAT) to 610% (glutathione). A number of antioxidants in both lung and liver exhibited either immediate pre- or post-birth decreases in activity. These falls could not be attributed to the way in which the results were expressed: i.e. they were similar, expressed per unit DNA, per unit protein, or per g wet wt. Following birth, liver antioxidant capacity increased such that the highest enzyme activities or glutathione concentration were recorded at 66 days post-partum. In lung, only Mn-SOD and glutathione exhibited higher levels at 66 days postpartum than at birth. In combination, these results of pulmonary and hepatic antioxidant enzyme activity indicate that the lung is not unique in acquiring increased antioxidant protection in the final period of gestation. They also suggest that a tissue's antioxidant requirement is dictated more by metabolic rate (hence free radical production) than incident partial pressure of oxygen.

Crystallizable HIV-1 protease derived from expression of the viral pol gene in Escherichia coli.

A plasmid vector was used to express the HIV-1 pol open reading frame under the regulation of the bacterial trp promoter in Escherichia coli. This expression system has been used as a source of recombinant viral protease. The self-processed active enzyme was recovered from a soluble fraction of a bacterial cell lysate and purified by a procedure involving four steps of chromatography. The protocol yielded 0.3 mg of protease for each liter of bacterial culture. The protease formed tetragonal bipyramidal crystals which have been used in high-resolution X-ray diffraction studies.