Over the catalyst containing (VO)2P207 and -V0PO4, C3H8 was oxidized to acetic and acrylic acids with the selectivities of 30-36% and 30-38%, respectively. The addition of La2O3 and Dy2O3 onto the ...catalyst brought about an increase in the rate of carboxylic acid s formation and its selectivity. The formation rate of the carboxylic acids gave a maximum at 10--20 at% of La content. Enhanced selectivity of carboxylic acids was observed upon the addition of Bi2O3. The selectivity of acetone extraporated to 0 sec of W/F was estimated to about 6%, suggesting that there is a reaction path to acetone via isopropenyl radical, isopropenylperoxyl radical. Temperature programmed desorption spectra of NH3 and CO2from the VP-0 catalysts with and without La203 indicated that the addition of La2O3increased the amount of both weaker acidic sites and weaker basic sites. Comparing the formation rates of partial oxidation products over the La203 containing catalyst and that containing no La2O3 in the oxidation of C3H8, C3H6, and acrylic acid, it is concluded that added La2O3 mainly accelerates the rate of reaction via isopropenylperoxyl radical.
A new principle for the copper removal process, Electro-Chemical-Polishing (ECP), to replace CMP is demonstrated. ECP which leverages electrochemical dissolution of copper has removal rates ...determined by the imposed current, higher than 8000 A/min, while "planarization" is made by wiping out copper complexes at a wiping pressure ten times lower than that for CMP to form erosion- and scratch-free damascene copper interconnects. ECP is a promising replacement for CMP suitable for copper inlaid in fragile low-k materials.
In this paper, we propose a method to rapidly decide process orders which satisfy all constraints by adding some jobs from a set of spare jobs to a large number of jobs which have the constraints ...about each connection between jobs. This problem can be divided into two parts of problem, namely a process ordering problem in each partial set which is easy to satisfy all the constrains, and an ordering problem among partial sets which is difficult to satisfy all the constraints, by grouping a set of jobs whose characteristic is similarity into partial sets.
A fragile porous ultra-low-k (k=2.2) silica was successfully integrated at trench level in damascene copper by applying our previously reported 1 electro chemical polishing (ECP) technique for Cu. ...After removing Cu by ECP, the barrier (WN) was removed by low pressure (LP) CMP (<1 psi). Practical polishing rates were obtained for WN in LP-CMP, because of higher chemical sensitivity of WN compared to Ta(N). Compatibility of CVD barrier to porous low-k, excellent barrier performance in aggressive features and lower via resistance were achieved by a newly developed CVD/PVD stacked WN barrier.
Five hundred and sixty-one endocardial pacing leads implanted in the right ventricle of 502 patients between 1971 and 1990 were followed for up to 17 years regarding their complications, stimulation ...threshold behavior, and overall longevity. Lead tip dislodgement occurred in 16 leads (2.9%), in 14 of which dislodgement occurred within 2 months after implantation. The incidence of dislodgement was significantly smaller in tined leads than in nontined leads. Lead conductor fracture occurred in 19 leads (3.4%), in 15 of which fracture occurred within 5 years after implantation. Two particular sites of lead fracture were identified; i.e., one within the pacemaker pocket and the other at a particular point in the subclavian vein between the clavicle and the first rib. Fixation ligature in the former site and the venopuncture point for lead insertion in the latter site are thought to be related to lead fracture. Other complications included insulator break in 3 leads (0.5%), exit block in 7 leads (1.2%), and poor sensing in 2 leads (0.4%). The cumulative survival of leads was 94.1±2.7% (mean±95% confidence interval) at 5 years, 86.3±6.3% at 10 years, and 74.2±14.0% at 15 years after implantation. The minimal stimulation threshold, lead impedance and R wave amplitude were all found to be stable for up to 10 years, and there were no tendencies toward higher stimulation threshold during the observation period of this study.
Optically active α-halocarboxylic acids and derivatives are important and versatile building blocks in organic synthesis. Lewis acid assisted chiral Brönsted acid (LBA) was recently prepared in situ ...from tin(IV) tetrachloride and optically pure binaphthol and shown to be an effective reagent for enantioselective protonation of pro- chiral silyl enol ethers and ketene bis(trialkylsilyl) acetals. In this paper we describe highly enantioselective protonation of ketene bis(trimethylsilyl) acetals prepared from α-aryl-α-haloaeetic acids using LBA. This is a new methodology for the enantioselective synthesis of α-aryl-α-haloacetic acid derivatives, and the commercially available chiral binaphthol can be recovered efficiently for reuse.
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