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High molecular weight vinyl esters and carbonates based on oligo(ethylene glycol), oligomeric fatty acids and poly(hexamethylene carbonate), as alternatives for potentially cytotoxic acrylate based monomers have been structured by Additive Manufacturing Technologies (AMTs) like Microstereolithography (μ-SLA), Digital Light Processing (DLP) and Two-Photon Induced Photopolymerization (TPIP). With these techniques feature resolutions down to 10 μm (μ-SLA and DLP) or even 200 nm (TPIP) can be obtained.
This new class of monomers exhibits LC50 values for cytotoxicity up to two orders of magnitude lower than acrylate references. Beside a high reactivity of the resin, the shrinkage and the mechanical properties of the final part material are another essential parameter. Low molecular weight monomers are very reactive and lead to densely cross-linked materials which suffer from high shrinkage and strains within the cured material. Therefore, mixtures of high molecular weight vinyl esters/carbonates with low molecular weight crosslinkers have been evaluated regarding their photoreactivity and mechanical properties.
We report on three cases of patients whose primary symptoms of myasthenia gravis were related to the upper aerodigestive tract. Symptoms had been present unrecognized in all patients for up to three years, and one patient subsequently developed a myasthenic crisis. We highlight the clinical features of myasthenia gravis to allow its prompt recognition in patients presenting to the ENT surgeon or physician.
We describe the operation of lasers having active regions composed of InP self-assembled quantum dots embedded in In0.5Al0.3Ga0.2P grown on GaAs (100) substrates by MOCVD. InP quantum dots grown on In0.5Al0.3Ga0.2P have a high density on the order of about 1-2x10 cm-2 with a dominant size of about 10-15 nm for 7.5 ML growth. These In0.5Al0.3Ga0.2P/InP quantum dots have previously been characterized by atomic-force microscopy, high-resolution transmission electron microscopy, and photoluminescence. We report here the 300K operation of optically pumped red-emitting quantum dots using both double quantum-dot active regions and quantum-dot coupled with InGaP quantum-well active regions. Optically and electrically pumped 300K lasers have been obtained using this active region design; these lasers show improved operation compared to the lasers having QD-based active regions with threshold current densities as low as Jth ∼ 0.5 KA/cm2.
We describe the operation of lasers having active regions composed of InP selfassembled quantum dots embedded in In0.5Al0.3Ga0.2P grown on GaAs (100) substrates by MOCVD. InP quantum dots grown on In0.5Al0.3Ga0.2P have a high density on the order of about 1–2×10 cm−2 with a dominant size of about 10–15 nm for 7.5 ML growth. These In0.5Al0.3Ga0.2P/InP quantum dots have previously been characterized by atomic-force microscopy, high-resolution transmission electron microscopy, and photoluminescence. We report here the 300K operation of optically pumped red-emitting quantum dots using both double quantum-dot active regions and quantum-dot coupled with InGaP quantum-well active regions. Optically and electrically pumped 300K lasers have been obtained using this active region design; these lasers show improved operation compared to the lasers having QD-based active regions with threshold current densities as low as Jth ∼ 0.5 KA/cm2.
High-resolution optical and NIR observations are used to constrain a dynamical model of the circumnuclear star forming (SF) region in the barred galaxy M100 (NGC 4321). Small leading arms observed in our K-band image of the nuclear region have been reproduced in numerical modeling of M100, a galaxy with a double inner Lindblad resonance (ILR). We also present preliminary optical and NIR observations of NGC 6951: a barred galaxy with circumnuclear SF showing a distinctly different behavior to M100 at 2.2µm.
Internal photoemission of both electrons and holes is used to investigate the movement of the mobility edges in high quality intrinsic, undoped hy-drogenated amorphous silicon (a-Si:H) with temperature and electrical field. The electron mobility edge is found to move up in energy by ∼40meV between 298K and 120K. On the other hand, the hole mobility edge remains essentially unchanged between 298K and 160K. The injection (and collection) of photoemitted holes is less efficient than that for electrons and in the films studied could not be measured below 160K.
Many of the chemical and physical interactions that take place in natural soil-water systems are strongly influenced by the presence of natural organic polyelectrolytes. The most common of these organic polyelectrolytes is humic acid, which is defined as the alkali soluble, acid insoluble fraction of soil organic matter. Over a hundred years of experimental data have demonstrated that a wide variety of different materials having different physical and chemical properties fit this definition. If we are to make any progress in understanding the role of humic materials in soil-water systems, then we must have a classification system which, as far as possible, provides a unique taxonomic definition for each separate molecular species that falls into the category of humic acid.
Various triphormic dioctahedral minerals and their dehydroxylation and rehydroxylation products have been examined by chemical, thermal, X-ray and infra-red absorption techniques. Since minerals with high Al-for-Si substitution do not rehydroxylate readily under the mild conditions used, attention was focused largely upon pyrophyllite and montmorillonite. Rehydroxylation occurs rapidly at about 400–500°C. Infra-red spectra indicate that there is a structural resemblance between the layers of all the dehydroxylates and that the rehydroxylates possess regions similar to untreated pyrophyllite. X-ray results show that stacking of the layers cannot be identical in the various samples. Although the structures could not be determined, the scheme proposed by Jonas for the rehydroxylate could not be reconciled with experimental results: nor does rehydroxylated montmorillonite resemble the abnormal form.
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