The segregation of elements in high-refractory-content single-crystal nickel-based superalloys

Nickel-based superalloys are complex alloys that contain ten to 15 elements that are widely used in industries where high-temperature strength and corrosion resistance are required. Alloy additions commonly include Cr, Co, W, Ta, Al, Ti, Re, Mo, and, in some alloys, Ru. Each of these additions can affect the as-cast microstructure due to differences in elemental segregation. A better understanding of the effects of typical additions to nickel-based superalloys on the segregation of the elements in the alloy can help identify potential improvements in the processing of current alloys and the development of new alloys. Therefore, the effects of several common alloying additions on solidification segregation and defects were evaluated. In general, an increase in the degree of elemental segregation was observed with increases in each of the elements listed except cobalt and molybdenum. Increased levels of cobalt and molybdenum resulted in reductions in the segregation of most of the elements in the alloy. For more information, contact G.E. Fuchs, University of Florida, Department of Materials Science and Engineering, 116 Rhines Hall, Gainesville, FL 82611, USA; (352) 846-3317; fax (352) 392-7219; e-mail gfuch@mse.ufl.edu.     

Frequency of isolation of Salmonella from protective foot covers worn in broiler houses as compared to drag-swab sampling

In this study we tested the hypothesis that the frequency of Salmonella isolation from protective foot covers worn in individual broiler production houses would compare favorably to isolation rates obtained from conventional drag-swab methods. Salmonella was detected with equal frequency from protective foot covers and drag-swab assemblies on nine individual broiler farms over three separate sampling periods. Salmonella was detected in 13 of a total 27 individual samplings by culturing the protective foot covers, whereas positive detections occurred in 16 of a total 27 samplings when using the drag-swab method. Of the total number of houses identified as positive, these frequencies were unaltered when evaluated against the flock status of each farm at the time of sampling. Both methods were equally as likely to detect Salmonella when houses were either vacant (awaiting the placement of the next flock) or occupied (currently housing chickens of any age). In addition to highlighting the development of a potential new Salmonella monitoring technique, this study reinforces our current understanding regarding the importance of stringent biosecurity practices on poultry farms.     

Lisuride prevents learning and memory impairment and attenuates the increase in extracellular dopamine induced by transient global cerebral ischemia in rats

In this experiment, we tested the efficacy of neuroprotection with lisuride, a dopamine agonist, using the 4-vessel occlusion rat model. Functional improvement was evaluated with two behavior tests exploring learning and memorization capacity in the rat, the Morris water maze and the 14-unit T-maze, 18 days after ischemia. Extracellular dopamine levels during ischemia were determined in search of a possible neuroprotection mechanism. Dopamine and its metabolites, DOPAC and HVA, as well as the serotonin metabolite, 5-HIAA, were assayed with HPLC-EC, in striatal extracellular fluid obtained by in vivo microdialysis in the awake rat. Lisuride was administered at a total dose of 10 ng by continuous intrastriatal infusion or at the dose of 0.5 mg/kg by i.p. infusion, 160 minutes before onset of ischemia for the neurochemical study and at the dose of 0.5 mg/kg via i.p. infusion, 1 hour before occlusion of the carotid arteries, for the behavior tests. Behavioral testing showed significantly better recovery in both sets of behavioral tests, with more pronounced positive results with the 14-unit T-maze, in comparison with the saline-treated animals. Microdialysis confirmed a significant attenuation of the ischemia-induced dopamine surge, whatever the mode of administration, compared with saline-treated animals. These results show that lisuride offers significant neuroprotection from the effect of experimental transient global forebrain cerebral ischemia in the rat; the mechanism would imply, at least in part, reduced levels of extracellular dopamine.     

Home environment and cognitive development in the first 3 years of life: A collaborative study involving six sites and three ethnic groups in North America.

Attempted to examine the generalizability of environment/development relationships among 3 ethnic groups across the first 3 years of life. Social status did not show a consistent relationship to either quality of home environment or children's developmental status across the various groups. Results indicated a fairly consistent relationship between HOME scores and children's developmental status, although there were some ethnic and social status differences in the relationship. Measures of specific aspects of the child's home environment, such as parental responsivity and availability of stimulating play materials, were more strongly related to child developmental status than global measures of environmental quality such as SES. When the child's developmental status and early home environment were both very low, the likelihood of poor developmental outcomes was markedly increased compared with cases when only one was low. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of clonidine on cerebral blood flow velocity, carbon dioxide cerebral vasoreactivity, and response to increased arterial pressure in human volunteers

BACKGROUND: Because patients may be taking clonidine chronically or may be receiving it as a premedication before surgery, the authors investigated its effect on cerebral hemodynamics. METHODS: In nine volunteers, middle cerebral artery mean blood flow velocity (Vm) was measured using transcranial Doppler ultrasonography (TCD). CO2 vasoreactivity was measured before clonidine administration (preclonidine), 90 min after clonidine, 5 microg/kg orally, then following restoration of mean arterial pressure (MAP) to the preclonidine level. In addition, Vm was measured after a phenylephrine-induced 30-mmHg increase in MAP. RESULTS: After clonidine administration, Vm decreased from 62 +/- 9 to 48 +/- 8 cm/s (P < 0.01), and MAP decreased from 86 +/- 10 to 63 +/- 5 mmHg (P < 0.01; mean +/- SD). Clonidine decreased the CO2 vasoreactivity slope from 2.2 +/- 0.4 to 1.2 +/- 0.5 cm x s(-1) x mmHg(-1) (P < 0.05); restoring MAP to the preclonidine level increased the slope to 1.60 +/- 0.5 cm x s(-1) x mmHg(-1), still less than the preclonidine slope (P < 0.05). CO2 vasoreactivity expressed as a percentage change in Vm, decreased after clonidine, 3.5 +/- 0.8 versus 2.4 +/- 0.8 %/mmHg (P < 0.05); this difference disappeared after restoration of MAP, 3.1 +/- 1.2 %/mmHg. With a 30-mmHg increase in MAP, Vm increased by 13% before and after clonidine (P < 0.05). CONCLUSIONS: Clonidine, 5 microg/kg orally, decreases Vm and slightly attenuates cerebral CO2 vasoreactivity, therefore decreased cerebral blood flow and mildly attenuated CO2 vasoreactivity should be anticipated.     

cis-Diaminedichloroplatinum(II) complexes reversibly bound to water-soluble polyaspartamide carriers for chemotherapeutic applications. II: Platinum coordination to ethylenediamine ligands attached to poly(ethylene oxide)-grafted carrier polymers

In continuation of previous investigations aiming at the development of macromolecular metal complexes for biomedical use, this communication describes poly(alkylene oxide)-grafted polymeric platinum complexes. The platinum-containing macromolecules are obtained from presynthesized polyaspartamide carriers bearing poly(ethylene/propylene oxide) side chains and hydroxyethyl side groups as hydrosolubilizing units in addition to ethylenediamine side group terminals for metal coordination. Platination is brought about by treatment of the carriers with tetrachloroplatinate(II) ion in aqueous solution at 25–60°C. pH 4–6. The polymeric products, purified by dialysis in aqueous solution, are isolated by freeze-drying in yields of 60–80%. Platinum contents are in the range of 4–15%. The metal is bound to the carrier through chelation with the ethylenediamine ligands, forming square-planarcis-dichloroethylenediamine-platinum(II) complex species as side-chain terminals. Initially, the product polymers dissolve smoothly in water. Although on room-temperature storage in the solid state they gradually turn insoluble as a consequence of intermolecular solid-state interaction, solubility is retained on low-temperature storage and in frozen aqueous solutions.Presented in part at the Fifth International Symposium on Macromolecule-Metal Complexes. September 29–October 3, 1993. Bremen, Germany. For Part I of this Series, see Ref. 1.     

Altered wound arginine metabolism by corticosterone and retinoic acid

The objective of this study is to study the pharmacokinetics of imipenem-cilastatin in patients with anuria related to multiorgan failure during continuous venovenous hemodialysis (CVVHD) at a fixed blood flow rate of 60 ml/min, fixed dialysate flow rate of 20 ml/min, and drainage flow rate of 1-3 mil/min. A prospective open label study was designed in an intensive care unit in a university hospital. Six patients who required mechanical ventilation and inotropic agents and exhibited acute anuric renal failure were examined. Intravenous imipenem-cilastatin, 500/500 mg, was administered over 30 mins. Blood samples were obtained from the inlet and the outlet of the dialyzer and dialysate samples from the outlet before and at 0.0, 0.5, 1.0, 2.0, 3.0, 6.0, 9.0, and 12.0 hrs after infusion ended. The peak and trough concentrations of imipenem were 32.47 +/- 6.69 micrograms/ml and 1.12 +/- 0.46 micrograms/ml, respectively, whereas those of cilastatin were 50.05 micrograms/ml +/- 14.80 and 9.53 +/- 3.25 micrograms/ml, respectively. The half life was 2.79 +/- 0.3 hr for imipenem, and 6.67 +/- 0.93 hr for cilastatin. Total body clearance of imipenem was 89.4 +/- 17.5 ml/min, including the clearance by CVVHD of 18.7 +/- 1.2 ml/min, and corresponding values for cilastatin were 31.7 +/- 9.0 ml/min and 13.7 +/- 3.4 ml/min. In conclusion, in patients with anuria, the elimination of imipenem-cilastatin was constant during CVVHD. The recommended regimen in patients with anuria who receive CVVHD in this setting was estimated as intravenous imipenem-cilastatin, 500/500 mg, every 12 hrs.     

Substratum topography influences susceptibility of Salmonella enteritidis biofilms to trisodium phosphate

Established (48- and 72-h) Salmonella enteritidis biofilms grown in glass flow cells with or without artificial crevices (0.5-, 0.3-, and 0.15-mm widths) were subjected to a 10% trisodium phosphate (TSP) solution under different flow regimens (0.3, 0.6, 1.2, and 1.8 cm s-1). The abundance of biofilm remaining after TSP treatment, the biocidal efficacy of TSP, and the factors which contributed to bacterial survival were then evaluated by using confocal laser microscopy and a fluorescent viability probe. Biofilm age affected the amount of biofilm which remained following a 15-s exposure to TSP. After TSP treatment of 48-h biofilms, 29% of the original biofilm remained at the biofilm-liquid interface, whereas 75% of the biofilm remained at the base (the attachment surface). Following TSP treatment of 72-h biofilms, 27% of the biofilm material remained at the biofilm-liquid interface, 73% remained at the 5-micron depth, and 91% remained at the biofilm base. Results obtained using the BacLight viability probe indicated that TSP exposure killed all the cells in 48-h biofilms, whereas in the thicker 72-h biofilms, surviving bacteria (approximately 2% of the total) were found near the 5- and 0-micron depths. In the presence of artificially constructed crevices, an inverse relationship was shown to exist between bacterial survival (ranging from approximately 13 to 83% of total biofilm material) and crevice width. This relationship was further influenced by the velocity of TSP flow; high TSP flow velocities (1.8 cm s-1) resulted in the lowest number of surviving bacteria at the base of crevices (approximately 42% survival). Extended time courses demonstrated that after TSP stress was relieved, biofilms continued to grow within crevices but not in systems without crevices. It is suggested that advective TSP flux into crevices and through the biofilm matrix was enhanced under conditions of high flow. These results suggest that the inherent roughness of the substratum on which the biofilm was grown and the timing of TSP application are important factors controlling the efficacy of TSP treatment.     

Characterization of vertebral strength using digital radiographic analysis of bone structure

Bone mineral densitometry (BMD) is useful in predicting fracture risk, but, unfortunately, there is a significant degree of overlap in BMD measurements of patients who have a high risk of fracture and patients with a low risk of fracture. In this study, a method of characterizing trabecular bone structure in digitized radiographs of vertebrae is proposed and assessed. A significant correlation between bone "structure" and the compressive strength of vertebral bodies was found. The utility of the parameter for distinguishing between "weak" and "strong" bone samples was assessed using receiver operating characteristic (ROC) analysis. Using this analysis, the structural parameter produced an area under the ROC of 0.88 +/- 0.05, while a bone density measure produced an area of 0.79 +/- 0.07. The results suggest that the addition of a measure of bone structure to the conventional measures of bone density may prove useful in predicting the quality of bone when considering surgical or medical intervention for osteoporotic conditions.