Resonant Charge Transfer of Hydrogen Rydberg Atoms Incident on a Cu(100) Projected Band-Gap Surface.

The charge transfer (ionization) of hydrogen Rydberg atoms (n=25-34) incident on a Cu(100) surface is investigated. Unlike fully metallic surfaces, where the Rydberg electron energy is degenerate with the conduction band of the metal, the Cu(100) surface has a projected band gap at these energies, and only discrete image states are available through which charge transfer can take place. Resonant enhancement of charge transfer is observed for Rydberg states whose energy matches one of the image states, and the integrated surface ionization signals (signal versus applied field) show clear periodicity as a function of n as the energies come in and out of resonance with the image states. The surface ionization dynamics show a velocity dependence; decreased velocity of the incident H atom leads to a greater mean distance of ionization and a lower field required to extract the ion. The surface ionization profiles for "on resonance" n values show a changing shape as the velocity is changed, reflecting the finite field range over which resonance occurs.

Charge transfer of Rydberg H atoms at a metal surface.

The charge transfer of Rydberg hydrogen atoms at a metal surface is investigated for the first time. The surface ionization of Stark states with various electron density distributions with respect to the surface is examined. Unlike the nonhydrogenic species studied previously, genuine control over the orientation of the electronic wave function in the surface-ionization process is demonstrated. A comparison of the results for a range of collisional velocities for the most redshifted Stark state with principal quantum numbers n=20-36 with the classical over-the-barrier approach shows a good agreement for the onset of the ion signal, but the shallow rise in signal is not accounted for. An excellent fit of the experimental results can be achieved using a simple semiempirical model.

Bite the bullet: lead poisoning after ingestion of 206 lead bullets.

A 45-y-o male with a history of schizophrenia was admitted to a local VA psychiatric unit. Five days later, endoscopy due to abdominal pain, gastrointestinal bleeding and blood hemoglobin of 5.6 g/dL revealed bullets in the stomach. On subsequent radiograph, > 50 bullets were visualized in the stomach and intestines. Poison Center recommendations included whole bowel irrigation and a blood lead level. After poor results with gastrointestinal decontamination and a repeat radiograph showing > 100 cartridges, surgical intervention was considered but not performed due to perceived risk of bullet detonation from electrocautery. The blood lead was reported as 391 mcg/dL. Calcium EDTA therapy was initiated, followed by aggressive gastrointestinal decontamination. Four days of whole bowel irrigation facilitated passage of 206 cartridges over the next 10 days. The patient was discharged on a 14-day course of 600 mg Succimer tid to treat the bone lead deposits and blood lead level of 49 mcg/dl. An outpatient visit 6 w later showed the blood lead level had dropped to 24 mcg/dl. Aggressive gastrointestinal decontamination and calcium EDTA and Succimer administration successfully treated an ingestion lead bullets and the resulting lead poisoning.

Unplanned endotracheal extubation in the intensive care unit.

STUDY OBJECTIVE: To identify the frequency, outcome, and factors associated with unplanned endotracheal extubation (UE) in the intensive care unit (ICU). DESIGN: Prospective study. SETTING: An urban, university trauma-surgical ICU. PATIENTS: 96 intubated ICU patients who underwent 101 episodes of UE. INTERVENTIONS: Patient, nursing, respiratory, and demographic factors associated with UE and patient outcome were determined for one year. Results were presented to nursing staff. The incidence of UE as a function of the total number of ventilator days was determined for one year post nursing education. ENDPOINTS: Patients with UE were identified. Patients with reintubation were followed until final extubation. MEASUREMENTS AND MAIN RESULTS: 85% of UE were self-extubations and 15% were accidental. Self-extubations occurred with equal frequency during all three nursing shifts in alert or agitated patients who were not being weaned. Accidental extubations occurred during the day shift in less alert patients and were associated with transport procedures and the use of rotary beds. Overall, 57% of patients were reintubated and most reintubations were in the first hour. Difficulty with reintubation was common, and one patient who could not be reintubated died. There were significantly fewer UE per ventilator day after nursing education. CONCLUSIONS: Patients should be observed closely after unplanned extubation, although many may not require reintubation. Reintubation can be quite difficult, necessitating highly skilled airway management. Attention to associated risk factors may decrease the incidence of both accidental and self-extubation.