15 research outputs found
Surface Aggregate Structure of Nonionic Surfactants on Silica Nanoparticles
The self-assembly of two nonionic surfactants, pentaethylene glycol
monododecyl ether (C12E5) and n-dodecyl-{\ss}-maltoside ({\ss}-C12G2), in the
presence of a purpose-synthesized silica sol of uniform particle size (diameter
16 nm) has been studied by adsorption measurements, dynamic light scattering
and small-angle neutron scattering (SANS) using a H2O/D2O mixture matching the
silica, in order to highlight the structure of the surfactant aggregates. For
C12E5 strong aggregative adsorption onto the silica beads, with a high plateau
value of the adsorption isotherm above the CMC was found. SANS measurements
were made at a series of loadings, from zero surfactant up to maximum surface
coverage. It is found that the spherical core-shell model nicely reproduces the
SANS data up to and including the local maximum at q = 0.42 nm-1 but not in the
Porod region of high q, indicating that the surface area of the adsorbed
surfactant is underestimated by the model of a uniform adsorbed layer. A
satisfactory representation of the entire scattering profiles is obtained with
the model of micelle-decorated silica beads, indicating that C12E5 is adsorbed
as spherical micellar aggregates. This behaviour is attributed to the high
surface curvature of the silica which prevents an effective packing of the
hydrophobic chains of the amphiphile in a bilayer configuration. For the
maltoside surfactant {\ss}-C12G2 very weak adsorption on the silica beads was
found. The SANS profile indicates that this surfactant forms oblate ellipsoidal
micelles in the silica dispersion, as in the absence of the silica beads
Determination of the oxygen, carbon and vacancy concentration in solar-grade silicon and correlation with the hydrogen diffusivity
Die Europäische Wirtschaftsgemeinschaft auf dem Weg zum einheitlichen Binnenmarkt und zur Steuergemeinschaft im Jahr 1992: Wissenschaftliches Kolloqium aus Anlass des 70. Geburtstages von Henning von Armin, Saarbrücken, 14. Mai 1988
Behavioral observations and measurements of aerial pheromone in a mating disruption trial against pea moth Cydia nigricana F (Lepidoptera, Tortricidae)
Synthetic sex pheromone of the pea moth Cydia nigricana, (E,E)-8,10-dodecadien-1-yl acetate (E8,E10-12:Ac), was applied in a 3-ha pea field at a rate of 17 g/ha, in two different dispenser formulations. Aerial concentrations within pea canopy, as determined by a field electroantennogram (EAG) apparatus, were 2 and 3 ng/m(3) in the two dispenser treatments. The validity of the EAG measurements was corroborated by sampling of field air, followed by gas chromatographic quantification of E8,E10-12:Ac. Males were attracted to fresh dispensers releasing E8,E10-12:Ac plus less than 2% of the antagonistic E, Z; Z, E; and Z, Z isomers. Two days after placement, the proportion of these isomers had increased to 6%. Males were then no longer attracted to the dispensers, but were observed to fly out of the treated field. Male attraction to calling females was almost entirely suppressed, and attraction to traps baited with synthetic pheromone was significantly reduced. Larval infestation in the pheromone-treated field was 2%, compared to 36% in a control field
Non-invasive positive pressure ventilation for the treatment of severe stable chronic obstructive pulmonary disease: a prospective, multicentre, randomised, controlled clinical trial
BACKGROUND: Evidence is weak for the ability of long-term non-invasive positive pressure ventilation (NPPV) to improve survival in patients with stable hypercapnic chronic obstructive pulmonary disease (COPD). Previous prospective studies did not target a reduction in hypercapnia when adjusting ventilator settings. This study investigated the effect of long-term NPPV, targeted to markedly reduce hypercapnia, on survival in patients with advanced, stable hypercapnic COPD.
METHODS: This investigator-initiated, prospective, multicentre, randomised, controlled clinical trial enrolled patients with stable GOLD stage IV COPD and a partial carbon dioxide pressure (PaCO2) of 7 kPa (51\ub79 mm Hg) or higher and pH higher than 7\ub735. NPPV was targeted to reduce baseline PaCO2 by at least 20% or to achieve PaCO2 values lower than 6\ub75 kPa (48\ub71 mm Hg). Patients were randomly assigned (in a 1:1 ratio) via a computer-generated randomisation sequence with a block size of four, to continue optimised standard treatment (control group) or to receive additional NPPV for at least 12 months (intervention group). The primary outcome was 1-year all-cause mortality. Analysis was by intention to treat. The intervention was unblinded, but outcome assessment was blinded to treatment assignment. This study is registered with ClinicalTrials.gov, number NCT00710541.
FINDINGS: Patients were recruited from 36 respiratory units in Germany and Austria, starting on Oct 29, 2004, and terminated with a record of the vital status on July 31, 2011. 195 patients were randomly assigned to the NPPV group (n=102) or to the control group (n=93). All patients from the control group and the NPPV group were included in the primary analysis. 1-year mortality was 12% (12 of 102 patients) in the intervention group and 33% (31 of 93 patients) in the control group; hazard ratio 0\ub724 (95% CI 0\ub711-0\ub749; p=0\ub70004). 14 (14%) patients reported facial skin rash, which could be managed by changing the type of the mask. No other intervention-related adverse events were reported.
INTERPRETATION: The addition of long-term NPPV to standard treatment improves survival of patients with hypercapnic, stable COPD when NPPV is targeted to greatly reduce hypercapnia
A Wavelength-shifting Optical Module (WOM) for in-ice neutrino detectors
We report on the development status of a single-photon sensor that employs wavelength-shifting and light-guiding techniques to maximize the collection area while minimizing the dark noise rate. The sensor is tailored towards application in ice-Cherenkov neutrino detectors embedded in inert and cold, low-radioactivity and UV transparent ice as a detection medium, such as IceCube-Gen2 or MICA. The goal is to decrease the energy threshold as well as to increase the energy resolution and the vetoing capability of the neutrino telescope, when compared to a setup with optical sensors similar to those used in IceCube. The proposed sensor captures photons with wavelengths between 250 nm and 400 nm. These photons are re-emitted with wavelengths above 400 nm by a wavelength shifting coating applied to a 90 mm diameter polymer tube. The tube guides the light towards a small-diameter PMT via total internal reflection. By scaling the results from smaller laboratory prototypes, the total efficiency of the proposed detector for a Cherenkov spectrum is estimated to exceed that of a standard IceCube optical module. The status of the prototype development and the performance of its main components will be discussed
A Wavelength-shifting Optical Module (WOM) for in-ice neutrino detectors
We report on the development status of a single-photon sensor that employs wavelength-shifting and light-guiding techniques to maximize the collection area while minimizing the dark noise rate. The sensor is tailored towards application in ice-Cherenkov neutrino detectors embedded in inert and cold, low-radioactivity and UV transparent ice as a detection medium, such as IceCube-Gen2 or MICA. The goal is to decrease the energy threshold as well as to increase the energy resolution and the vetoing capability of the neutrino telescope, when compared to a setup with optical sensors similar to those used in IceCube. The proposed sensor captures photons with wavelengths between 250 nm and 400 nm. These photons are re-emitted with wavelengths above 400 nm by a wavelength shifting coating applied to a 90 mm diameter polymer tube. The tube guides the light towards a small-diameter PMT via total internal reflection. By scaling the results from smaller laboratory prototypes, the total efficiency of the proposed detector for a Cherenkov spectrum is estimated to exceed that of a standard IceCube optical module. The status of the prototype development and the performance of its main components will be discussed
A Wavelength-shifting Optical Module (WOM) for in-ice neutrino detectors
We report on the development status of a single-photon sensor that employs wavelength-shifting and light-guiding techniques to maximize the collection area while minimizing the dark noise rate. The sensor is tailored towards application in ice-Cherenkov neutrino detectors embedded in inert and cold, low-radioactivity and UV transparent ice as a detection medium, such as IceCube-Gen2 or MICA. The goal is to decrease the energy threshold as well as to increase the energy resolution and the vetoing capability of the neutrino telescope, when compared to a setup with optical sensors similar to those used in IceCube. The proposed sensor captures photons with wavelengths between 250 nm and 400 nm. These photons are re-emitted with wavelengths above 400 nm by a wavelength shifting coating applied to a 90 mm diameter polymer tube. The tube guides the light towards a small-diameter PMT via total internal reflection. By scaling the results from smaller laboratory prototypes, the total efficiency of the proposed detector for a Cherenkov spectrum is estimated to exceed that of a standard IceCube optical module. The status of the prototype development and the performance of its main components will be discussed