Current Results

Here we survey with some critical commentary recent enumerative work from 1999 through May 2001. We divide up the discussion into different broad categories, separating off the work on fullerene isomer problems from other isomer work, in part because of the activity in dealing with fullerenes, and in part because, to deal best with fullerenes, Polya theory has played a lesser role. 

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Since any current resulting from tire anodic reaction must be consumed by tire catlrodic reaction, tire catlrodic current,7, must be equal to tire airodic current As a consequence, tire equilibrium potential of a metal (e.g. Fe) tlrat is immersed into air aqueous electrolyte will be adjusted by tire condition tlrat = j This is... 

Nonfaradaic Currents Faradaic currents result from a redox reaction at the electrode surface. Other currents may also exist in an electrochemical cell that are unrelated to any redox reaction. These currents are called nonfaradaic currents and must be accounted for if the faradaic component of the measured current is to be determined. 

The ion current resulting from collection of the mass-separated ions provides a measure of the numbers of ions at each m/z value (the ion abundances). Note that for this ionization method, all ions have only a single positive charge, z = 1, so that m/z = m, which means that masses are obtained directly from the measured m/z values. Thus, after the thermal ionization process, m/z values and abundances of ions are measured. The accurate measurement of relative ion abundances provides highly accurate isotope ratios. This aspect is developed more fully below. 

Selectivity of propylene oxide from propylene has been reported as high as 97% (222). Use of a gas cathode where oxygen is the gas, reduces required voltage and eliminates the formation of hydrogen (223). Addition of carbonate and bicarbonate salts to the electrolyte enhances ceU performance and product selectivity (224). Reference 225 shows that use of alternating current results in reduced current efficiencies, especiaHy as the frequency is increased. Electrochemical epoxidation of propylene is also accompHshed by using anolyte-containing silver—pyridine complexes (226) or thallium acetate complexes (227,228). 

Substituents on the methine chain can stabilize the dye radical cation if the substituent (like methyl) is located on the high electron density carbons. However, no significant stabilization occurs when alkyl groups are on the alternate positions (like 9, 11 for the dication in Fig. 9). Current results for several dyes including die arbo cyanines and carbocyanines indicate that electronic stabilization of the dication radical lengthens the radical lifetime and also enhances the reversibiUty of the dimerization process (37). 

The siting of substations, electrical, geographic, economic, political, and aesthetic factors must be considered. The high voltages of the transmission system are utilized because the reduced currents result in more efficient power transmission. Therefore, substations are placed as close to the system loads as possible to minimize losses. This is con-... 

At the positive electrode the electronic current results in an increasing electron density. The electrode B/electrolyte system compensates this process by the consumption of electrons for the deposition of B+ ions ... 

In cerebellar Purkinje cells, a TTX-sensitive inward current is elicited, when the membrane was partially repolarized after strong depolarization. This resurgent current contributes to high-frequency repetitive firing of Purkinje neurons. The resurgent current results from open channel block by the cytoplasmic tail of the (34 subunit. The med Nav 1.6 mutant mice show defective synaptic transmission in the neuromuscular junction and degeneration of cerebellar Purkinje cells. 

The potential-step experiment can also be used to record the charge versus tune dependence. This is accomplished by integrating the current resulting from the... 

The mass spectrometric currents follow largely, but not completely the faradaic current signals. The contributions to the respective faradaic currents resulting from complete oxidation to CO2, which are calculated using the calibration constant K (see Section 13.2), are plotted as dashed lines in the top panels in Fig. 13.3. For the calculations of the partial reaction currents, we assumed six electrons per CO2 molecule formation and considered the shift in the potential scale caused by the time... 

Conversion of the m/z = 44 ion current into a partial faradaic reaction current for formaldehyde oxidation to CO2 (four-electron reaction) shows that, under these experimental conditions, formaldehyde oxidation to CO2 is only a minority reaction pathway (dashed line in Fig. 13.6a). Assuming CO2 and formic acid to be the only stable reaction products, most of the oxidation current results from the incomplete oxidation to formic acid (dotted hne in Fig. 13.6a). The partial reaction current for CO2 formation on Pt/Vulcan at 0.6 V is only about 30% of that during formic acid... 

However, in light of our current results it may be more correct to split this step into the foUowing ... 

In contrast to the other ionization detectors a decrease in the detector background current is measured rather than an increase in the number of ions or electrons generated. The detector standing current results from the bombardment of the carrier gas by beta electrons forming a plasma of positive ions. 

Albella and co-workers have also explained the prebreakdown deviation of the Ua(t) dependence in galvanostatic anodization from linearity. This is ascribed to increasing participation of electrons in the anodic current, resulting in the loss of current efficiency.296... 

With the number of known exoplanets increasing very fast, current results are giving us the chance to undertake the first statistical studies of the properties of the exoplanets, as well of their host stars [24,21,8]. This is bringing new interesting constraints for the models of planet formation and evolution. 

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