A study of the voltage and current efficiencies of fused salt AlCl3 electrolysis using bench scale cells

The fused salt electrolysis of AlCl₃ dissolved in LiCl-NaCl melts at 700°C was studied using bench scale cells employing graphite electrodes. The effects of AlCl₃ concentration, forced convection, interelectrode spacing, and current density on the voltage, current, and energy efficiencies of the process were investigated. At a practical cell voltage of 3.05 V and current density of 15 kA·m^?2 the electrical energy consumption per kg of aluminum produced by the AlCl₃ process was about 32 MJ, compared with a typical value of 52 MJ·kg^?1 for the Hall-Héroult electrolysis.     

Long-term outcome in acute myocardial infarction patients admitted to hospitals with and without on-site cardiac catheterization facilities. MITI Investigators. Myocardial Infarction Triage and Intervention

BACKGROUND: Previous studies have documented the strong association between availability of on-site cardiac catheterization facilities and increased use of coronary angiography in patients with acute myocardial infarction (AMI). Although these studies have shown little influence of the availability of catheterization labs on hospital mortality, no long-term follow-up has been reported. METHODS AND RESULTS: From a cohort of 12,331 AMI patients admitted to 19 Seattle area hospitals, we compared long-term outcome in 7985 patients admitted to hospitals with and 4346 patients admitted to hospitals without on-site catheterization labs. During the index hospitalization, patients admitted to hospitals with on-site catheterization were more likely to undergo coronary angiography (67.1% versus 39.3%, P<.0001), coronary angioplasty (32.5% versus 13.2%, P<.0001), or coronary bypass surgery (12.5% versus 9.5%, P<.0001). At 3-year follow-up, patients admitted to hospitals with on-site catheterization labs were more likely to undergo postdischarge angiography (19.2% versus 15.2%, P=.0001) and coronary angioplasty (11.6% versus 8.2%, P<.0001). This was associated with approximately $2500.00 per patient in higher cumulative costs. Despite this higher rate of procedure use, there was no association between admission to a hospital with on-site catheterization facilities and lower long-term mortality (multivariate hazard ratio, 1.0; 95% CI, 0.93 to 1.1., the hazard being associated with admission to hospitals with on-site catheterization facilities). CONCLUSIONS: In an urban area with unconstrained patient transfer mechanisms and high overall cardiac procedure use rates, AMI patients admitted to hospitals without on-site catheterization facilities were managed with fewer procedures during hospitalization and follow-up. This more conservative treatment approach was not associated with any observed increase in long-term mortality.     

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.     

Performance of a randomization test for single-subject (15)O-water PET activation studies

We adapted and implemented a permutation test (Holmes 1994) to single-subject positron emission tomography (PET) activation studies with multiple replications of conditions. That test determines the experimentwise alpha error as well as location and extent of focal activations in each individual. Its performance was assessed in five normal volunteers, using (15)O-H2O-PET data acquired on a high-resolution scanner, with septa retracted (3D mode), during functional activation by repeating words versus resting (four replications each). Calculated alpha errors decreased and the size of activated tissue volumes (voxels with P < or = 0.05) increased with increasing filter kernel size applied to the difference images. At a filter kernel of 12 mm Gaussian full width at half maximum, significant focal activations were seen bilaterally in superior temporal cortex, including Brodmann's areas 41 and 42, in all five subjects. Additional foci were detected in the precentral gyrus, left inferior frontal gyrus, supplementary motor area, and cerebellum of several subjects. The average CBF increase in activated voxels ranged from 17.6% to 28.7%. Activated volumes were smaller than those detected with a standard parametric test procedure. We conclude that the permutation test is a less sensitive procedure, having the advantage of not depending on unproven distributional assumptions, that detects strong activation foci in individual subjects with high reproducibility.     

The coenzyme A-synthesizing protein complex and its proposed role in CoA biosynthesis in bakers'' yeast

An improved procedure is described for the recovery and purification of the coenzyme A-synthesizing protein complex (CoA-SPC) of Saccharomyces cerevisiae (bakers' yeast). The molecular mass of the CoA-SPC, determined prior to and following its purification, is estimated by Sephacryl S-300 size exclusion chromatography to be between 375,000-400,000. Two previously unreported catalytic activities attributed to CoA-SPC have been identified. One of these is CoA-hydrolase activity which catalyzes the hydrolysis of CoA to form 3',5'-ADP and 4'-phosphopantetheine, and the other is dephospho-CoA-pyrophosphorylase activity which catalyzes a reaction between 4'-phosphopantetheine and ATP to form dephospho-CoA. The dephospho-CoA then reacts with ATP, catalyzed by the dephospho-CoA-kinase, to reform CoA. This sequence of reactions, referred to as the CoA/4'-phosphopantetheine cycle, provides a mechanism by which the 4'-phosphopantetheine can be recycled to form CoA. Each turn of the cycle utilizes two mol of ATP and produces one mol of ADP, one mol of PPi, and one mol of 3',5'-ADP. Other than the hydrolysis of CoA by CoA-SPC, the 4'-phosphopantetheine for the cycle apparently could be supplied by alternate sources. One alternate source may be the conventional pathway of CoA biosynthesis. Intact CoA-SPC has been separated into two segments. One segment is designated apo-CoA-SPC and the other segment segment is referred to as the 10,000-15,000 M(r) subunit. The 5'-ADP-4'-pantothenic acid-synthetase, 5'-ADP-4'-pantothenylcysteine-synthetase, 5'-ADP-4'-pantothenylcysteine-decarboxylase, and CoA-hydrolase activities reside in the apo-CoA-SPC segment of CoA-SPC. Whereas the dephospho-CoA-kinase and the dephospho-CoA-pyrophosphorylase activities reside in the 10,000-15,000 M(r) subunit. Thus, the 10,000-15,000 M(r) subunit mimics the bifunctional enzyme complex that catalyzes the final two steps in the conventional pathway of CoA biosynthesis.     

Solution structure of a brodimoprim analogue in its complex with Lactobacillus casei dihydrofolate reductase

Two-dimensional (2D) double-quantum-filtered correlation spectroscopy (DQF-COSY), total correlation spectroscopy (TOCSY), nuclear Overhauser effect spectroscopy (NOESY), and rotating-frame NOESY (ROESY) spectra were used to assign essentially all the protons in a 1:1 complex of Lactobacillus casei dihydrofolate reductase formed with an analogue of the antibacterial drug brodimoprim [2,4-diamino-5-(3',5'-dimethoxy-4'-bromobenzyl)pyrimidine]. The analogue has a 4,6-dicarboxylic acid side chain substituted on the 3'-O position designed to interact with the Arg 57 and His 28 residues in L. casei dihydrofolate reductase; it binds a factor of 10(3) more tightly to the enzyme than does the parent compound. Thirty-eight intermolecular and 11 intramolecular NOEs were measured involving the bound brodimoprim-4,6-dicarboxylic acid analogue. These provided the distance constraints used in conjunction with an energy minimization and simulated annealing protocol (using Discover from Biosym Ltd.) to dock the brodimoprim analogue into dihydrofolate reductase. In calculations where side chains and backbone fragments for binding-site residues were allowed flexibility, 90% of the 40 calculated structures had reasonable covalent geometry and none of them had NOE distance violations of greater than 0.36 A. The conformations of the aromatic rings in the bound ligand were well-defined in all the structures, with torsion angles tau 1 = -153 degrees +/- 4 degrees (C4-C5-C7-C1') and tau 2 = 53 degrees +/- 4 degrees (C5-C7-C1'-C2'): the aromatic rings of the ligand occupied essentially the same space in all the calculated structures (root mean square deviation value 1.83 A). Inclusion of the electrostatic interactions into the energy minimizations indicated that structures in which the 4,6-dicarboxylate group of the ligand interacts with the side chains of Arg 57 and His 28 are of low energy. Significant differences in side-chain and backbone conformations were detected between binding-site residues in the enzyme complexes with the brodimorpim analogue and methotrexate.