Nickel may be produced in acidic chloride-sulfate based electrolytes. Nickel is initially deposited on stainless steel or titanium cathodes to produce starting sheets while chlorine gas is evolved on ...DSA anodes. Stress in the nickel deposit may cause bending of the cathode sheet. In addition, irregular growth such as dendrite formation may occur. In extreme cases, short-circuiting of electrodes will happen. Fundamental electrochemical studies of the initial stages of the electrodeposition process may give valuable information for obtaining smooth nickel deposits.
Electrochemical experiments of nickel deposition were carried out on titanium substrates using cyclic voltammetry and potential step, and examined with SEM imaging. The measurements were performed at different deposition potentials and times to get an overall picture of the nucleation and growth of nickel on titanium substrates. Further deposition studies have been performed using
in situ
AFM to study the whole process from single nickel nuclei to a cohesive layer, and determine the nucleation mode and characteristics. The effects of electrolyte composition and pH will be presented.
The pre-treatment of the substrate is important for the nucleation and properties of the nickel deposit. The figure illustrates the different nucleation overpotential for a smooth and rough titanium substrate.
Figure 1
Aims
Cryothermic ablation using a cryoballoon is a novel technique which has been used to treat paroxysmal atrial fibrillation. In this study, we wanted to test this technique to treat focal atrial ...tachycardias (ATs) from the pulmonary veins (PV).
Methods and Results
Five patients (four women, one man, mean age 43 ± 16 years) with severe symptoms due to focal AT originating from a PV were studied. A single transseptal puncture was done. After confirmation of the diagnosis by conventional mapping, a 23 or 28 mm cryoballoon catheter was positioned in the PV of interest. Freezing was done for 300 s and repeated at least once before attempts to induce arrhythmia. All patients were successfully treated. Total procedure and fluoroscopy time was 138 ± 55 and 26 ± 21 min, respectively. During a follow-up of 10 ± 7 months no clinical recurrences occurred.
Conclusion
Cryoablation using a cryoballoon might be an easy and safe tool to treat ATs originating from the PV with reasonable procedure time.
Nickel may be produced by electrolysis in acidic chloride based electrolytes. Nickel is initially deposited on stainless steel or titanium starting sheets while chlorine gas is evolved on DSA anodes. ...Stress in the nickel deposit may cause bending of the cathode sheet. Also irregular growth such as dendrite formation may occur. In extreme cases short circuiting of electrodes will happen. Fundamental electrochemical studies of the initial stages of the electrodeposition process may give valuable information for obtaining smooth nickel deposits.
Initial experiments were carried out by using cyclic voltammetry on cathodes of titanium. Ongoing studies are performed by potential step chronoamperometry to study the nucleation and growth of nickel on titanium cathode substrates. Experiments to study the effect of electrolyte composition, pH and temperature on the nickel deposition process are under way. Electrolysis to deposit macroscopic amounts of nickel will be carried out to characterize the deposits by optical methods.
To study the extent to which lifelong physical training can affect cardiovascular capacity, left ventricular function, and myocardial perfusion in elderly men.
Ten healthy male veteran endurance ...athletes aged 73 +/- 3 yr (mean +/- SD) and a control group of 12 sedentary or moderately physically active healthy subjects aged 75 +/- 2 yr were studied. Echocardiographic examinations at rest and exercise stress tests were performed. Gated blood pool scans and myocardial perfusion scintigraphy were recorded at rest and during exercise. Maximal VO2 was 41 +/- 7 mL.kg-1.min-1 in the athletes and 26 +/- 5 mL.kg-1.min-1 in the controls (P < 0.001). Echocardiographic measures of systolic and diastolic function at rest were better in the athletes. The ejection fraction during exercise was also higher in the athletes (P = 0.003). Seven of the 10 athletes, but none of the controls, had pathological myocardial perfusion findings.
By endurance training, a high level of physical capacity can be maintained late in life. The superior cardiovascular function in the veteran athletes, compared with the untrained controls was due to both better systolic and diastolic left ventricular function. Myocardial perfusion defects in athletes should be judged with caution, as this finding is common both in veteran athletes and as previously shown, in young athletes.
Background: Beneficial training outcomes have been reported in sedentary patients with chronic heart failure (CHF) after exercise training. However, data on training effects in previously trained ...patients, as well as comparisons of different exercise modes, are lacking. The aim of this study is to compare exercise training on a cycle ergometer (major muscle mass) and aerobic knee-extensor training (minor muscle mass) in previously trained patients with CHF.
Methods and Results: Twenty-four men and women (age, 63 ± 10 years mean ± SD) with stable, moderate CHF (left ventricular ejection fraction, 30% ± 11%) who had completed their first exercise training period more than 1 year ago were allocated to either the exercise or control group. After stratification for sex, age, ejection fraction, and cardiac output response, the training group was further randomized to either cycle ergometer or knee-extensor training for 8 weeks. The control and training patients did not differ at baseline, and the measured variables did not change in the control group during the 8 weeks. Citrate synthase activity in skeletal muscle increased after cycle training (23%;
P < .02) and knee-extensor training (45%;
P < .008), and blood lactate concentration at submaximal intensities decreased (
P < .04) in both groups. However, only after knee-extensor training did the peak oxygen uptake increase (19%;
P < .01) and sympathetic nervous system activity, measured as plasma norepinephrine concentration at rest (
P < .05) and during exercise (
P < .008), decrease. Minnesota Living with Heart Failure questionnaire scores also showed improvement in the health-related quality of life (
P < .05) only after knee-extensor training.
Conclusion: Physical training is beneficial in previously trained patients with CHF. Aerobic training involving a minor muscle mass shows greater efficiency than training involving a major muscle mass.
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IJS, IMTLJ, KILJ, KISLJ, NUK, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
We tested the hypothesis that the extent of signs of ischaemia detected by vectorcardiography (VCG) during elective coronary angioplasty (percutaneous transluminal coronary angioplasty; PTCA) is ...related to systolic and diastolic myocardial velocities, as determined by tissue Doppler echocardiography. A total of 15 patients undergoing PTCA (12 men/three women; age 61+/-9 years), without prior myocardial infarction and with an ejection fraction of >50%, were included. The balloon inflation was repeated three times, with minimum intervals of 2 min between inflations. Tissue Doppler echocardiography was performed, in an apical two- or four-chamber view, before and at the end of each inflation. Peak systolic velocity, time-to-peak systolic velocity (TTP), peak early (E(m)) and late (A(m)) diastolic velocities, the E(m)/A(m) ratio and isovolumic relaxation time were measured in the basal segments of the left ventricle. VCG recordings were carried out during the whole procedure. ST vector magnitude (ST-VM) and ST change vector magnitude (STC-VM) were monitored. The total duration and area of each VCG change during inflation were calculated for each patient. Isovolumic relaxation time, peak E(m) and A(m) values and the E(m)/A(m) ratio did not change significantly during inflation. Peak systolic velocity decreased (6.7+/-2.0 to 5.3+/-1.9 cm/s; P<0.001) and TTP increased (157+/-60 to 192+/-60 ms; P<0.01) during inflation. Both STC-VM time (r=-0.68, P<0.01) and STC-VM area (r=-0.68, P<0.01) were related to peak systolic velocity during inflation. STC-VM time was also related (r=0.55, P<0.05) to the difference in peak systolic velocity during compared with before inflation. ST-VM was less closely related to peak systolic velocity. Thus the duration and degree of ischaemia, as measured by VCG, are related to peak systolic velocity in the basal segments of the left ventricle.
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