707 research outputs found
In situ infrared absorption spectroscopy of dusty plasmas
In situ, time-resolved Fourier transform infrared spectroscopy was used to study particulate formation in rf discharges in mixtures of silane, argon, and nitrogen. The spectra were taken at a maximum rate of 20 Hz. The discharge conditions were chosen such that previous calibrations of the time evolutions of particle size and density could be used. The measurements indicate that the onset of the solid-state vibrational absorptions of the SiH and SiH2 bands only takes place after the nucleation and coagulation phase have finished; it coincides with the previously predicted start of the deposition of amorphous hydrogenated silicon on the particles. The dissociation of the silane feed gas is found to be in the range of 30%, and its time development suggests that also the large-scale dissociation of silane only starts after the coagulation phase. This is in agreement with previously observed trends for the electron temperature. If silicon partilces are grown in the plasma, and the silane flow is stopped, the Si particles stay trapped in the glow. The infrared measurements, however, show that they almost completely oxidize: the SiH/SiH2 vibrations disappear and a strong SiO vibration appears. If nitrogen gas is allowed into the plasma, the SiO vibration is replaced by a SiN vibration. © 1996 American Vacuum Societ
Tinea nigra by Hortaea werneckii, a report of 22 cases from Mexico
Tinea nigra is a superficial mycosis caused by Hortaea werneckii.
It is an infrequent asymptomatic infection that affects human palms and soles,
and is mostly observed in tropical countries. We evaluate retrospectively
twenty-two confirmed cases of tinea nigra from a total of eleven yr
(1997–2007) and discuss the epidemiology, clinical features and
treatment of this disease. In twelve cases, adults were involved, in 10,
children. In nineteen cases the disorder was located on palms of hands and in
three on soles of feet. In all cases, the obtained isolates were
morphologically identified as Hortaea werneckii and the
identification of ten isolates was retrospectively confirmed with the help of
sequences of the internal transcribed spacer regions of the ribosomal DNA. The
patients received topical treatment with Whitfield ointment, ketoconazole,
bifonazole, or terbinafine. Treatment with keratolytic agents and topical
antifungals was effective
Transport of argon ions in an inductively coupled high-density plasma reactor
The first direct observation of the velocity distribution of the metastable Ar1*~2G9/2! ions in the presheath of an inductively coupled plasma has been achieved by using the Doppler shifted laser induced fluorescence technique. Drift of the ions along the electric field in the presheath is observed and distribution functions of the velocity in both parallel and perpendicular directions, relative to the E field, are deduced at 5 and 40 mTorr. Present results show that in high density plasmas the velocity distribution of the metastable ions is directly related to that of the ground state argon ions. Neutral gas temperature of around 600 K is also measured from the absorption profile of a diode laser beam, set on one of the 772.4 nm argon lines
In situ infrared absorption spectroscopy of dusty plasmas
International audienceIn situ, time-resolved Fourier transform infrared spectroscopy was used to study particulate formation in rf discharges in mixtures of silane, argon, and nitrogen. The spectra were taken at a maximum rate of 20 Hz. The discharge conditions were chosen such that previous calibrations of the time evolutions of particle size and density could be used. The measurements indicate that the onset of the solid-state vibrational absorptions of the SiH and SiH 2 bands only takes place after the nucleation and coagulation phase have finished; it coincides with the previously predicted start of the deposition of amorphous hydrogenated silicon on the particles. The dissociation of the silane feed gas is found to be in the range of 30%, and its time development suggests that also the large-scale dissociation of silane only starts after the coagulation phase. This is in agreement with previously observed trends for the electron temperature. If silicon partilces are grown in the plasma, and the silane flow is stopped, the Si particles stay trapped in the glow. The infrared measurements, however, show that they almost completely oxidize: the SiH/SiH 2 vibrations disappear and a strong SiO vibration appears. If nitrogen gas is allowed into the plasma, the SiO vibration is replaced by a SiN vibration
Pseudovirgaria, a fungicolous hyphomycete genus
The genus Pseudovirgaria, based on P. hyperparasitica, was recently introduced for a mycoparasite of rust sori of various species of Frommeëlla, Pucciniastrum and Phragmidium in Korea. In the present study, an older name introduced by Saccardo based on European material, Rhinotrichum griseum, is shown to resemble P. hyperparasitica. Morphological study and ITS barcodes from fresh collections of R. griseum from Austria on uredinia and telia of Phragmidium bulbosum on Rubus spp. reveal that it is distinct from P. hyperparasitica. The status of the genus Rhinotrichum, introduced for a fungus occurring on dry wood, remains unclear. Pseudovirgaria grisea comb. nov. is therefore proposed for the mycoparasite occurring on rust fungi in Europe, and an epitype is designated from the recent collections
Capillary Condensation and Interface Structure of a Model Colloid-Polymer Mixture in a Porous Medium
We consider the Asakura-Oosawa model of hard sphere colloids and ideal
polymers in contact with a porous matrix modeled by immobilized configurations
of hard spheres. For this ternary mixture a fundamental measure density
functional theory is employed, where the matrix particles are quenched and the
colloids and polymers are annealed, i.e. allowed to equilibrate. We study
capillary condensation of the mixture in a tiny sample of matrix as well as
demixing and the fluid-fluid interface inside a bulk matrix. Density profiles
normal to the interface and surface tensions are calculated and compared to the
case without matrix. Two kinds of matrices are considered: (i) colloid-sized
matrix particles at low packing fractions and (ii) large matrix particles at
high packing fractions. These two cases show fundamentally different behavior
and should both be experimentally realizable. Furthermore, we argue that
capillary condensation of a colloidal suspension could be experimentally
accessible. We find that in case (ii), even at high packing fractions, the main
effect of the matrix is to exclude volume and, to high accuracy, the results
can be mapped onto those of the same system without matrix via a simple
rescaling.Comment: 12 pages, 9 figures, submitted to PR
Continuous-time random-walk approach to normal and anomalous reaction-diffusion processes
We study the dynamics of a radioactive species flowing through a porous
material, within the Continuous-Time Random Walk (CTRW) approach to the
modelling of stochastic transport processes. Emphasis is given to the case
where radioactive decay is coupled to anomalous diffusion in locally
heterogeneous media, such as porous sediments or fractured rocks. In this
framework, we derive the distribution of the number of jumps each particle can
perform before a decay event. On the basis of the obtained results, we compute
the moments of the cumulative particle distribution, which can be then used to
quantify the overall displacement and spread of the contaminant species.Comment: 6 pages, 4 figure
SARS-CoV-2 incidence in secondary schools; the role of national and school-initiated COVID-19 measures
Efficacy of a loading dose of IV salbutamol in children with severe acute asthma admitted to a PICU:a randomized controlled trial
The optimal dose regimen for intravenous (IV) treatment in children with severe acute asthma (SAA) is still a matter of debate. We assessed the efficacy of adding a salbutamol loading dose to continuous infusion with salbutamol in children admitted to a pediatric intensive care unit (PICU) with SAA. This multicentre, placebo-controlled randomized trial in the PICUs of four tertiary care children’s hospitals included children (2–18 years) with SAA admitted between 2017 and 2019. Children were randomized to receive either a loading dose IV salbutamol (15 mcg/kg, max. 750 mcg) or normal saline while on continuous salbutamol infusion. The primary outcome was the asthma score (Qureshi) 1 h after the intervention. Analysis of covariance models was used to evaluate sensitivity to change in asthma scores. Serum concentrations of salbutamol were obtained. Fifty-eight children were included (29 in the intervention group). Median baseline asthma score was 12 (IQR 10–13) in the intervention group and 11 (9–12) in the control group (p = 0.032). The asthma score 1 h after the intervention did not differ significantly between the groups (p = 0.508, β-coefficient = 0.283). The median increase in salbutamol plasma levels 10 min after the intervention was 13 μg/L (IQR 5–24) in the intervention group and 4 μg/L (IQR 0–7) in the control group (p = 0.001). Side effects were comparable between both groups. Conclusion: We found no clinical benefit of adding a loading dose IV salbutamol to continuous infusion of salbutamol, in children admitted to the PICU with SAA. Clinically significant side effects from the loading dose were not encountered.What is Known:• Pediatric asthma guidelines struggle with an evidence-based approach for the treatment of SAA beyond the initial steps of oxygen suppletion, repetitive administration of inhaled β2-agonists, and systemic steroids.• During an SAA episode, effective delivery of inhaled drugs is unpredictable due to severe airway obstruction.What is New:• This study found no beneficial effect of an additional loading dose IV salbutamol in children admitted to the PICU.• This study found no clinically significant side effects from the loading dose
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