CAFTURE AND RECYCLE OF BYPASSING BUBBLE GAS IN A FLUIDIZED BED: THE “BUBBLE EATER”

The bubble eater is a device which can sense, capture, and recycle bubble gas in a bubbling fluidized bed. The theory describing the enhancement of reactant gas conversion are presented and illustrated by means of a numerical example.     

Pheromone regulated production of inositol-(1, 4, 5)-trisphosphate in the mammalian vomeronasal organ

Social behaviors of most mammals are profoundly affected by chemical signals, pheromones, exchanged between conspecifics. Pheromones interact with dendritic microvilli of bipolar neurons in the vomeronasal organ (VNO). To investigate vomeronasal signal transduction pathways, microvillar membranes from porcine VNO were prepared. Incubation of such membranes from prepubertal females with boar seminal fluid or urine results in an increase in production of inositol-(1, 4, 5)-trisphosphate (IP3). The dose response for IP3 production is biphasic with a GTP-dependent component at low stimulus concentrations and a nonspecific increase in IP3 at higher stimulus concentrations. The GTP-dependent stimulation is mimicked by GTPgammaS and blocked by GDPbetaS. Furthermore, the GTP-dependent component of the stimulation of IP3 production is sex specific and tissue dependent. Studies with monospecific antibodies reveal a G alpha(q/11)-related protein in vomeronasal neurons, concentrated at their microvilli. Our observations indicate that pheromones in boar secretions act on vomeronasal neurons in the female VNO via a receptor mediated, G protein-dependent increase in IP3. These observations set the stage for further investigations on the regulation of stimulus-excitation coupling in vomeronasal neurons. The pheromone-induced IP3 response also provides an assay for future purification of mammalian reproductive pheromones.     

In vitro studies on the use of clay, clay minerals and charcoal to adsorb bovine rotavirus and bovine coronavirus

Rotaviruses are the leading cause and coronaviruses are the major contributors of acute gastroenteritis in the young of various mammalian and avian species. Despite numerous trials and decades of research, vaccines have limited efficacy particularly for calves. As an alternative method of controlling infection, we have investigated broad spectrum antiviral agents that are not discriminatory among various viruses. This report involves testing a variety of adsorbent agents including charcoal, clay, and clay minerals to adsorb rotavirus and coronavirus in vitro. Results revealed that all the adsorbent agents had good to excellent capability of adsorbing rotavirus and excellent capability of adsorbing coronavirus. Percent adsorptions ranged from 78.74% to 99.89% for rotavirus and 99.99% for coronavirus; while sand (negative control) was < 0.01%. A high affinity binding was present as determined by a low percent desorption (0.06-3.09%). However, the adsorbent bound virus complex retained, and may have actually enhanced, infectivity.     

The failure of an F/A-18 trailing edge flap hinge

During a flight over sea, the right-hand trailing-edge flap (TEF) from an RAAF F/A-18 separated. Although the flap was not recovered, the mode of failure suggested that the outboard hinge lug was first to fail. A fleet-wide inspection of the TEF outer hinge lugs disclosed two other cracked hinge lugs. Examination of these cracks revealed that they had propagated as the result of a combination of corrosion and fatigue, in that the corrosive environment appeared to have accelerated the fatigue crack growth rate. Laboratory experiments indicated that, in a salt solution, the 7050 aluminium alloy from which the lugs were manufactured is susceptible to corrosion fatigue and that the observed cracking matched that on the cracked lugs: corrosion fatigue was therefore suspected to have been a contributing factor in the unexpected failure. Quantitative fractography on the fatigue cracks, combined with several assumptions and deductions, including information about the failure size of the crack gained from witness marks found on the monoball bearing of the failed TEF, led to an estimate of the fatigue crack growth rate. This crack growth rate and the short service life clearly indicated the limitations of the then-current non-destructive inspection (NDI) technique, and a more sensitive inspection method was developed to assist in the maintenance of adequate RAAF flying hours between inspections. This failure investigation provided an excellent example of how fractography, laboratory experiments and NDI can be combined to determine a possible cause of failure and to establish remedial measures for the fleet.     

A 150 MHz 0.6 μm BiCMOS superscalar microprocessor

An implementation of the Pentium microprocessor architecture in 0.6 μm BiCMOS technology is described. Power dissipation is reduced and performance is enhanced over the previous generation. Processor features, implementation technology, and circuit techniques are discussed. An internal clock rate of 150 MHz is achieved at 3.7 V and -55°C     

Influence of DNA repair by ada and ogt alkyltransferases on the mutational specificity of alkylating agents

We investigated the influence of the alkyltransferases (ATases) encoded by the ada and ogt genes of Escherichia coli on the mutational specificity of alkylating agents. A new mutational assay for selection of supF- mutations in shuttle-vector plasmids was used. Treating plasmid-bearing bacteria with N-methyl-N-nitrosourea (MNU), N-ethyl-N-nitrosourea (ENU), and ethyl methanesulfonate (EMS) dramatically increased the mutation frequency (from 33-fold to 789-fold). The vast majority of mutations (89-100%) were G:C-->A:T transitions. This type of mutation increased in ada- (MNU) or ogt- (ENU) bacteria, suggesting that repair of O6-methylguanine by ada ATase and repair of O6-ethylguanine by ogt ATase contribute mainly to the decrease in G:C-->A:T transitions. The analysis of neighboring base sequences revealed an overabundance of G:C-->A:T transitions at 5'-GG sequences. The 5'-PuG bias increased in ATase-defective cells, suggesting that these sequences were not refractory to repair. G:C-->A:T transitions occurred preferentially in the untranscribed strand after in vivo exposure. That this strand specificity was detected even in bacteria devoid of ATase activity (ada- ogt-) and not after in vitro mutagenesis suggests a bias for damage induction rather than for DNA repair. Highly significant differences were found between the in vivo and in vitro incidences of G:C-->A:T substitutions at the two major hotspots, positions 123 (5'-GGG-3'; antisense strand) and 168 (5'-GGA-3'; sense strand). These results are explained by differences in the probability of formation of stem-loop structures in vivo and in vitro.