Improved field emission from multiwall carbon nanotubes with nano-size defects produced by ultra-low energy ion bombardment

Multiwalled carbon nanotubes were irradiated with ultra-low energy (few eV) nitrogen and hydrogen ions using a microwave discharge. These ultra-low energy plasma-ions remain confined to the nanotube walls, transferring their maximum energy to the carbon atoms, and produce extraordinary structural changes to the carbon nanotube pillars as well as within the carbon nanotubes. Conical shaped emitters and nanotube structures with nano-defects are produced that exhibit remarkable field emission with ultra-low turn-on electric field (∼0.16 V/μm) and a >300-fold increase in the maximum emission current density compared to non-irradiated nanotubes. Doping of nitrogen is also identified due to such irradiation processes.     

Experimental investigation of the catalytic cracking of methane over a supported Ni catalyst

TGA experiments on the catalytic cracking of methane and methane diluted with hydrogen over a 5 wt% Ni/γ‐alumina catalyst at 500°C and 1 and 10 bar are described. Carbon deposition on the catalyst, as expressed in specific weight of carbon, varies with time. Eventually, the deposition stops because of deactivation. The specific weight at this point depends on the hydrogen partial pressure and there is also a weak dependence on the degree of contact between catalyst particles. A model based on assuming carbon deposition proceeds through whisker formation and growth, and deactivation occurs through encapsulation adequately describes the experimental observations up to 20 vol% hydrogen in the feed.     

Inflammatory aneurysm of the ascending aorta and aortic arch

Transbronchial needle aspiration (TBNA) is a valuable, minimally invasive procedure for diagnosing and staging lung cancer in patients, but it is underutilized by practicing pulmonologists. To assess the approach to TBNA of current pulmonary Fellows, we recorded their computerized interactive responses during the 1995 American College of Chest Physicians Fellows' Conference. Among 109 Fellows attending, only 10% reported that they routinely (> or = 85% of cases) performed TBNA to diagnose or stage malignant disease, and 40% noted that they rarely (< or = 5% of cases) performed it. They estimated their diagnostic TBNA yields in patients with mediastinal cancer as follows: > or = 80% by 2% of Fellows; between 25% and 80% by 54% of Fellows; and < 25% by 45% of Fellows. They noted that the main limitations of TBNA at their institutions were suboptimal bronchoscopy technique (30%), technician support (1%), cytopathology support (14%), all of these factors (25%), or the belief that TBNA is not useful (30%). TBNA is currently underutilized and/or underemphasized at bronchoscopy training programs. Major modifications of Fellow experiences are necessary if TBNA is to impact optimally on patient management.     

Post-operative pyrexia in an orthopaedic unit

The causes of post operative pyrexia in an orthopaedic unit was studied prospectively in 520 patients who underwent surgery. Two hundred patients (38.4%) developed postoperative pyrexia as defined by having recorded high temperatures of over 38 degrees C on two occasions within 24 hours (excluding the first 24 hours post-operatively). The commonest causes of post-operative pyrexia were wound infection in 70 (13.4%), respiratory tract infections in 40 (7.6%) and malaria in 30 (5.7%) patients, while other causes were urinary tract infection in 20 (3.8%), thrombophlebitis in 15 (2.8%) and deep vein thrombosis in 15 (2.8%) of the patients; while ten (1.9%) patients had pyrexia of undetermined cause despite exhaustive clinical and laboratory workup. The other associated conditions in patients who developed pyrexia were diabetes mellitus in 20 (3.8%), HIV seropositivity and malignancy in 30 (5.7%) and six (1.1%) patients, respectively.     

The choice of the optimal schedules in the vaccination procedure against influenza in elderly subjects

The paper describes a clinical case of the cerebral hyperperfusion syndrome, a rare complication of carotid endarterectomy. The syndrome appeared as the generalized convulsive syndrome in the patient in the early postoperative period. In the context of clinical observation, the results of analysis of the literature are presented and the pathogenesis, diagnosis, therapy, and prevention of the cerebral hyperperfusion syndrome considered.