Field ionization of high-Rydberg fragments produced after inner-shell photoexcitation and photoionization of the methane molecule.

We have studied the production of neutral high-Rydberg (HR) fragments from the CH4 molecule at the C 1s → 3p excitation and at the C 1s ionization threshold. Neutral fragments in HR states were ionized using a pulsed electric field and the resulting ions were mass-analyzed using an ion time-of-flight spectrometer. The atomic fragments C(HR) and H(HR) dominated the spectra, but molecular fragments CH(x)(HR), x = 1-3, and H2(HR) were also observed. The production of HR fragments is attributed to dissociation of CH4(+) and CH4(2+) ions in HR states. Just above the C 1s ionization threshold, such molecular ionic states are created when the C 1s photoelectron is recaptured after single or double Auger decay. Similar HR states may be reached directly following resonant Auger decay at the C 1s → 3p resonance. The energies and geometries of the parent and fragment ions have been calculated in order to gain insight into relevant dissociation pathways.

Identification and treatment of sleep-disordered breathing in chronic spinal cord injury.

STUDY DESIGN: A follow up on an ongoing prospective cohort study. OBJECTIVE: Spinal cord injury or disorder (SCI/D) patients have higher rates of sleep-disordered breathing (SDB) than the general population. The objectives of this study were to examine predictors of SDB diagnosis and to estimate rates of SDB treatment in SCI/D patients. SETTING: A SCI clinical sleep research laboratory. METHODS: Twenty-eight SCI/D patients (7 women, age 42.8 ± 15.8 years; 16 cervical and 12 thoracic level injuries) completed a battery of questionnaires (Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), Berlin questionnaire (BQ) and fatigue severity scale (FSS)) and had one night of attended laboratory polysomnography (PSG). Participants were then notified of the results of their PSG and were interviewed approximately 1 year later to assess clinical outcomes. RESULTS: The majority of patients reported poor sleep quality on all questionnaires. On the basis of PSG, 22 (79%) patients had SDB (apnea-hypopnea index (AHI)⩾ 5 events per hour), and 17 (61%) had moderate/severe SDB (AHI⩾15 events per hour). Higher ESS scores were associated with a higher risk of AHI ⩾ 5; however, other questionnaires did not distinguish between those with and without SDB using either AHI cutoff. In follow-up interviews, only 50% of patients had spoken to a health-care provider about SDB and only six patients with SDB were prescribed treatment, four of whom were using the treatment at follow-up. CONCLUSION: SDB is common and severe among SCI/D patients. Screening questionnaires do not appear to differentiate between those with and without SDB. Even when SDB was recognized, many patients remained untreated. The increased prevalence of cardiovascular disease in SCI/D patients could represent a consequence of untreated SDB, and improving diagnosis and management of SDB has the potential to improve outcomes for these patients.

Role of the Renner-Teller effect after core hole excitation in the dissociation dynamics of carbon dioxide dication.

The fragmentation of the doubly-charged carbon dioxide molecule is studied after photoexcitation to the C 1s(1)2π(u) and O 1s(1)2π(u) states using a multicoincidence ion-imaging technique. The bent component of the Renner-Teller split states populated in the 1s→ π* resonant excitation at both the carbon and oxygen 1s ionization edges opens pathways to potential surfaces in highly bent geometries in the dication. Evidence for a complete deformation of the molecule is found in the coincident detection of C(+) and O(2)(+) ions. The distinct alignment of this fragmentation channel indicates rapid deformation and subsequent fragmentation. Investigation of the complete atomization dynamics in the dication leading to asymmetric charge separation shows that the primary dissociation mechanisms, sequential, concerted, and asynchronous concerted, are correlated to specific fragment kinetic energies. The study shows that the bond angle in fragmentation can extend below 20°.

Rapid biological synthesis of platinum nanoparticles using Ocimum sanctum for water electrolysis applications.

The leaf extract of Ocimum sanctum was used as a reducing agent for the synthesis of platinum nanoparticles from an aqueous chloroplatinic acid (H(2)PtCl(6)·6H(2)O). A greater conversion of platinum ions to nanoparticles was achieved by employing a tulsi leaf broth with a reaction temperature of 100 °C. Energy-dispersive absorption X-ray spectroscopy confirmed the platinum particles as major constituent in the reduction process. It is evident from scanning electron microscopy that the reduced platinum particles were found as aggregates with irregular shape. Fourier-transform infrared spectroscopy revealed that the compounds such as ascorbic acid, gallic acid, terpenoids, certain proteins and amino acids act as reducing agents for platinum ions reduction. X-ray diffraction spectroscopy suggested the associated forms of platinum with other molecules and the average particle size of platinum nanoparticle was 23 nm, calculated using Scherer equation. The reduced platinum showed similar hydrogen evolution potential and catalytic activity like pure platinum using linear scan voltammetry. This environmentally friendly method of biological platinum nanoparticles production increases the rates of synthesis faster which can potentially be used in water electrolysis applications.

Changes in QT dispersion during adenosine infusion.

BACKGROUND: QT dispersion (QTd) measurement during treadmill stress testing has been to shown to improve the accuracy of exercise electrocardiogram (ECG) in the detection of significant coronary artery disease (CAD). HYPOTHESIS: The aim of this study was to determine whether adenosine-induced changes in QTd could predict significant CAD and to assess its efficacy as a diagnostic index in patients undergoing adenosine stress test. METHODS: QT interval measurements were made in 57 consecutive patients undergoing adenosine sestamibi stress test. Patients with an abnormal stress test underwent coronary angiography. Patients with significant disease by coronary angiography (> 70% stenosis) were classified as having CAD (Group 1), and those with normal stress images and/or normal coronaries by angiography were classified as having no CAD (Group 2). RESULTS: QT dispersion increased from 28.2 +/- 4.5 to 43.8 +/- 4.5 ms with a delta QTd of 15.53 +/- 3.68 in Group 1 (p = 0.001) and from 28.4 +/- 2.6 to 34.8 +/- 2.8 ms with a delta QTd of 6.58 +/- 2.21 ms in Group 2 (p = 0.006). Patients in Group 1 had a significantly higher increase in QTd (delta QTd) than the patients in Group 2 (p < 0.03). Addition of delta QTd (> 10 ms) to the ST depression during adenosine infusion would increase the sensitivity of the ECG from 23 to 65% and decrease the specificity from 91 to 70% for diagnosis of significant CAD. CONCLUSIONS: delta QTd is significantly more prolonged in patients with CAD during adenosine infusion. It increases the sensitivity of the stress ECG in diagnosis of CAD during adenosine infusion when used as an adjuvant index.

Staphylococcal pericarditis following percutaneous transluminal coronary angioplasty.

Infectious complications occurring after percutaneous transluminal coronary angioplasty are uncommon. We are reporting a case of bacterial pericarditis developing 1 week after coronary angioplasty and stent implantation. Treatment with appropriate antibiotics and drainage of the infected pericardial effusion was followed by a protracted hospital course and eventual control of infection and discharge of the patient.

Results of Stent Supported Percutaneous Transluminal Coronary Angioplasty in Octogenarians With Coronary Artery Disease.

Between January 1995 and July 1998, percutaneous transluminal coronary angioplasty was performed on 27 lesions in 24 octogenarians. Half of the patients were African American. Women comprised 67% of the study group. Patients with unstable angina and myocardial infarction constituted 54% of the cohort. Two-thirds of the patients (83%) had single vessel disease with predominant class A and B lesion complexity of the angioplasty site. Acute success rate was 92%. Stents were successfully placed in 11 subjects (46%). None had acute myocardial infarction, emergency coronary artery bypass surgery, or stroke as a complication of the procedure. One patient presenting with acute myocardial infarction complicated by cardiogenic shock, died. Significant bleeding complications requiring blood transfusions occurred in 17% of patients. Of the patients, 23 (96%) were discharged in a clinically stable condition. Follow up during a two year period was completed in 21 patients (88%). One patient died of cancer. Four subjects (19%) underwent repeat percutaneous transluminal coronary angioplasty. One other patient had recurrent chest pain requiring multiple hospitalizations. The remaining 16 patients (76%) remained free of recurrence of angina. We concluded that percutaneous transluminal coronary angioplasty with stent placement can be performed in octogenarians with a high rate of clinical and angiographic success with an acceptable range of morbidity and mortality, and favorable long term (two year) outcome. (c) 2000 by CVRR, Inc.