Individual and combined effects of water quality and empty bed contact time on As(V) removal by a fixed-bed iron oxide adsorber: Implication for silicate precoating

The individual and combined effects of changes in water quality (i.e. pH, initial concentrations of arsenate (As(V)) and competing ions) and empty bed contact time (EBCT) on As(V) removal performance of a fixed-bed adsorber (FBA) packed with a nanostructured goethite-based granular porous adsorbent were systematically studied under environmentally relevant conditions. Rapid small scale column tests (RSSCTs) were extensively conducted at different EBCTs with synthetic waters in which pH and the concentrations of competing ions (phosphate, silicate, and vanadate) were controlled. In the absence of the competing ions, the effects of initial As(V) concentration, pH, and EBCT on As(V) breakthrough curves were successfully predicted by the homogeneous surface diffusion model (HSDM) with adsorption isotherms predicted by the extended triple layer model (ETLM). The interference effects of silicate and phosphate on As(V) removal were strongly influenced by pH, their concentrations, and EBCT. In the presence of silicate (≤21 mg/L as Si), a longer EBCT surprisingly resulted in worse As(V) removal performance. We suggest this is because silicate, which normally exists at much higher concentration and moves more quickly through the bed than As(V), occupies or blocks adsorption sites on the media and interferes with later As(V) adsorption. Here, an alternative operating scheme of a FBA for As(V) removal is proposed to mitigate the silicate preloading. Silicate showed a strong competing effect to As(V) under the tested conditions. However, as the phosphate concentration increased, its interference effect dominated that of silicate. High phosphate concentration (>100 μg/L as P), as experienced in some regions, resulted in immediate As(V) breakthrough. In contrast to the observation in the presence of silicate, longer EBCT resulted in improved As(V) removal performance in the presence of phosphate. Vanadate was found to compete with As(V) as strongly as phosphate. This study reveals the competitive interactions of As(V) with the competing ions in actual adsorptive treatment systems and the dependence of optimal operation scheme and EBCT on water quality in seeking improved As(V) removal in a FBA.     

Absorption of silicone fluid in a silicone elastomer

Measurements have been made of the absorption properties of a silicone fluid in a silicone elastomer, Aircast 3700, at temperatures between 0 and 150 °C. It was found that the diffusivity could be described by Arrhenius' law. The saturation fluid content was 20% at 0 °C, decreasing to 17% at 120 °C. The swelling was large, up to 26% at saturation, and approximately equalled the volume of fluid absorbed. A reverse thermal effect was observed and an attempt has been made to explain it.     

Self-implantation energy and dose effects on Ge solid-phase epitaxial growth

The effects of implantation energy and dose on Ge solid-phase epitaxial growth kinetics were studied using (0 0 1) Ge substrates self-implanted at energies of 20-150 keV and doses of 1 × 10¹⁴−2 × 10¹⁵ cm⁻². All implants produced a continuous amorphous layer, which was crystallized by annealing at 330 °C for 22-176 min. At lower doses, the growth velocity was implant energy-independent while at higher doses the growth rate tended to decrease with decreasing implant energy. The decrease in growth velocity with energy at higher doses is discussed in terms of possible implantation-induced stresses altering growth kinetics.     

Can duplex scan arterial mapping replace contrast arteriography as the test of choice before infrainguinal revascularization?

PURPOSE: Arteriography is the diagnostic test of choice before lower extremity revascularization, because it is a means of pinpointing stenotic or occluded arteries and defining optimal sites for the origin and termination of bypass grafts. We evaluated whether a duplex ultrasound scan, used as an alternative to arteriography, could be used as a means of accurately predicting the proximal and distal anastomotic sites in patients requiring peripheral bypass grafts and, therefore, replace standard preoperative arteriography. METHODS: Forty-one patients who required infrainguinal bypass grafts underwent preoperative duplex arterial mapping (DAM). Based on these studies, an observer blinded to the operation performed predicted what operation the patient required and the best site for the proximal and distal anastomoses. These predictions were compared with the actual anastomotic sites chosen by the surgeon. RESULTS: Whether a femoropopliteal or an infrapopliteal bypass graft was required was predicted correctly by means of DAM in 37 patients (90%). In addition, both anastomotic sites in 18 of 20 patients (90%) who had femoropopliteal bypass grafts and 5 of 21 patients (24%) who had infrapopliteal procedures were correctly predicted by means of DAM. CONCLUSION: DAM is a reliable means of predicting whether patients will require femoropopliteal or infrapopliteal bypass grafts, and, when a patient requires a femoropopliteal bypass graft, the actual location of both anastomoses can also be accurately predicted. Therefore, DAM appears able to replace conventional preoperative arteriography in most patients found to require femoropopliteal reconstruction. Patients who are predicted by means of DAM to require crural or pedal bypass grafts should still undergo preoperative contrast studies to confirm these results and to more precisely locate the anastomotic sites.     

Effect of SDS on Acid Milk Coagulability

ABSTRACT To study the importance of hydrophobic interaction on the mechanism of acid milk gel formation, milk coagulation process was monitored at 30 °C in presence of various levels of sodium dodecyl sulphate (SDS). As a function of the SDS concentration, acid milk coagulability was either enhanced or reduced. Main pH‐induced biochemical changes were preserved despite the presence of SDS (such as pH‐induced demineralization and pH‐induced protein solubilization). It could be assumed that SDS‐modified casein micelles ability to coagulate by lowering of pH might seem to be governed essentially by the level of SDS‐induced k‐casein micellar dissociation, at natural milk pH.     

Enterococci with acquired vancomycin resistance in pigs and chickens of different age groups

Results of isolation of glycopeptide-resistant enterococci from fecal samples of pigs and chickens were found to differ strongly depending upon the type and age of animals and isolation technique (direct selective plate or broth enrichment). Isolations were frequent in broiler chickens and in sows but rare in layer chickens.     

Intra-accumbens infusions of antisense oligodeoxynucleotides to one isoform of glutamic acid decarboxylase mRNA, GAD65, but not to GAD67 mRNA, impairs sustained attention performance in the rat

The effects of bilateral infusions of antisense oligodeoxynucleotides (ODNs) for the two isoforms of glutamic acid decarboxylase (GAD65; GAD67) into the nucleus accumbens on the performance of intact rats in a task designed to assess sustained attention were tested. The task required the animals to discriminate between signal and non-signal events. Signals and non-signals were presented randomly and unpredictably. The task generated all four response types of a sustained attention task, i.e., hits, misses, correct rejections, false alarms. Infusions of the scrambled sequence ODNs did not affect performance. Likewise, infusions of the GAD67 ODNs failed to produce any effect. However, infusions of the GAD65 ODNs into the nucleus accumbens resulted in a robust and reliable decrease in the relative number of hits. Similarly, the combined infusion of GAD65+67 ODNs impaired the hit rate but did not affect the animals' ability to reject non-signals. Following each treatment series, performance rapidly returned to baseline, further indicating the specificity and reversibility of the effects of the infusions of the ODNs. While these data suggest that translation arrest of specifically the GAD65 isoform of the enzyme in the nucleus accumbens impairs attentional performance, the neuronal mechanisms mediating these effects remain unsettled.