48 research outputs found
Excitation and relaxation in atom-cluster collisions
Electronic and vibrational degrees of freedom in atom-cluster collisions are
treated simultaneously and self-consistently by combining time-dependent
density functional theory with classical molecular dynamics. The gradual change
of the excitation mechanisms (electronic and vibrational) as well as the
related relaxation phenomena (phase transitions and fragmentation) are studied
in a common framework as a function of the impact energy (eV...MeV). Cluster
"transparency" characterized by practically undisturbed atom-cluster
penetration is predicted to be an important reaction mechanism within a
particular window of impact energies.Comment: RevTeX (4 pages, 4 figures included with epsf
Tricholithobezoar Causing Gastric Perforation
A bezoar is an intraluminal mass formed by the accumulation of undigested material in the gastrointestinal tract. Trichobezoar is a rare condition seen almost exclusively in young women with trichotillomania and trichotillophagia. When not recognized, the trichobezoar continues to grow, which increases the risk of severe complications such as gastric ulceration and even perforation. Formation of a gallstone within the trichobezoar (tricholithobezoar) is an event that has not yet been described. We report the case of a 22-year-old woman admitted to the emergency room with signals and symptoms of an epigastric mass and perforative acute abdomen. Radiological study revealed bilateral pneumoperitoneum. Personal history revealed depressive syndrome, trichotillomania and trichophagia. With a diagnosis of visceral perforation, an urgent exploratory laparotomy was performed. This confirmed the diagnosis of gastric perforation due to a large trichobezoar with the formation of a gastrolith that was removed by anterior gastrotomy. Biochemical study of the gastric stone revealed that it was composed of bile salts. There were no complications. The patient was discharged on the 5th postoperative day and was referred for psychiatric treatment
Testing effectiveness of the revised Cape Town modified early warning and SBAR systems: a pilot pragmatic parallel group randomised controlled trial
Abstract
Background
Nursesâ recognition of clinical deterioration is crucial for patient survival. Evidence for the effectiveness of modified early warning scores (MEWS) is derived from large observation studies in developed countries.
Methods
We tested the effectiveness of the paper-based Cape Town (CT) MEWS vital signs observation chart and situation-background-assessment-recommendation (SBAR) communication guide. Outcomes were: proportion of appropriate responses to deterioration, differences in recording of clinical parameters and serious adverse events (SAEs) in intervention and control trial arms. Public teaching hospitals for adult patients in Cape Town were randomised to implementation of the CT MEWS/SBAR guide or usual care (observation chart without track-and-trigger information) for 31âdays on general medical and surgical wards. Nurses in intervention wards received training, as they had no prior knowledge of early warning systems. Identification and reporting of patient deterioration in intervention and control wards were compared. In the intervention arm, 24âday-shift and 23 night-shift nurses received training. Clinical records were reviewed retrospectively at trial end. Only records of patients who had given signed consent were reviewed.
Results
We recruited two of six CT general hospitals. We consented 363 patients and analysed 292 (80.4%) patient records (n =â150, 51.4% intervention, n =â142, 48.6% control arm). Assistance was summoned for fewer patients with abnormal vital signs in the intervention arm (2/45, 4.4% versus (vs) 11/81, 13.6%, OR 0.29 (0.06â1.39)), particularly low systolic blood pressure. There was a significant difference in recording between trial arms for parameters listed on the MEWS chart but omitted from the standard observations chart: oxygen saturation, level of consciousness, pallor/cyanosis, pain, sweating, wound oozing, pedal pulses, glucose concentration, haemoglobin concentration, and âlooks unwellâ. SBAR was used twice. There was no statistically significant difference in SAEs (5/150, 3.3% vs 3/143, 2.1% P =â0.72, OR 1.61 (0.38â6.86)).
Conclusions
The revised CT MEWS observations chart improved recording of certain parameters, but did not improve nursesâ ability to identify early signs of clinical deterioration and to summon assistance. Recruitment of only two hospitals and exclusion of patients too ill to consent limits generalisation of results. Further work is needed on educational preparation for the CT MEWS/SBAR and its impact on nursesâ reporting behaviour.
Trial registration
Pan African Clinical Trials Registry, PACTR201406000838118. Registered on 2 June 2014, www.pactr.org
Structures and reactions of hydrated biomolecular cluster ions
Photo-induced reactions and metastable decompositions of
cluster ions containing glycine, tryptophan, tryptophanylglicine and
[Fe(III)-protoporphyrin]+ (hemin ions solvated with water
molecules are studied with electrospray ionization (ESI). The ESI ion source
is improved to produce hydrated biomolecular cluster ions. Metastable
decompositions of the hydrated clusters following primary mass selection are
measured to determine the incremental solvent binding energies for the
clusters by using evaporative ensemble model. From these experimental
findings, stability of the cluster ions is discussed in terms of
delocalization of ionic charges. We also measure the photodissociation
yields of mass-selected water clusters containing hemin+ ions at 355
and 532Â nm. The mass spectra of photofragments show the -cleavage of
carboxymethyl groups in addition to the evaporation of solvent molecules
Photo-induced reactions of hemin
Photo-induced reaction of [Fe(III)-protoporphyrin]+ (hemin+) ions solvated with
dimethylsulfoxide (DMSO) is investigated by using a tandem mass spectrometer with electrospray
ionization. We measure the photodissociation yields of mass-selected hemin+(DMSO)n clusters for n = 0â3 in the energy region of 15â800â28â200Â cm-1. The mass spectra of the fragment ions show the
ÎČ-cleavage of carboxymethyl groups in addition to the evaporation of solvent molecules. Yield of the
ÎČ-cleavage reaction is found to depend strongly on the excitation energy and the number of solvent
molecules. We also examine the metastable decomposition of the clusters following primary mass
selection and determine the incremental solvent binding energies and internal energies for the clusters
using evaporative ensemble model. From these results, we investigate the reaction mechanism of
ÎČ-cleavage of hemin+ ion