Defect formation in epitaxial oxide dielectric layers due to substrate surface relief

Defects were characterized in epitaxial (001) CeO₂ films deposited and planarizedin situ on patterned (001) LaAlO₃ substrates by ion beam assisted deposition (IBAD). A hill and valley structure with steps running parallel to the [100] LaAlO₃ axis was produced on the surface of the substrate by photolithography and ion beam etching prior to film deposition. A conformai epitaxial CeO₂ layer of ∼ 100 nm thickness was deposited on the heated substrate by e-beam evaporation. Lattice-matching between the e-beam film and the substrate was of the type: (001) CeO₂∥(001) LaAlO₃ and [110] CeO₂∥[100] LaAlO₃. Evaporative deposition of additional film onto the conformai layer was accompanied by bombardment with a 500 eV argon/oxygen ion beam to promotein situ planarization. Extreme lattice misfit for the orientation (001) CeO₂∥(001)LaAlO₃ and [001] CeO₂∥[001] LaAlO₃ caused formation of dislocations in the e-beam CeO₂ film in the vicinity of individual ledges in the substrate surface. Coherence of the CeO₂ film was locally lost in the step regions of the hill and valley structure. The large patterned steps, which are composed of numerous adjacent ledges in the LaAlO₃ surface, caused nucleation of CeO₂ with a tilt misalignment of up to ∼5‡ about the substrate [100]. Nucleation and growth of nonepitaxial CeO₂ crystallites was observed along the step regions of the film during the IBAD portion of deposition. Defect formation in the e-beam ceria layer due to substrate surface relief indicates that “lattice engineering≓ of multilayer epitaxial structures may not be possible when nonplanar surfaces are created during device fabrication. The IBAD CeO₂ layer was more defective than the conformai layer deposited without the impinging ion beam, even in the portions of the film where epitaxy was maintained throughout both layers.     

Electric Properties of Semiconductor Nanopillars

We studied the electrical transport through epitaxial, 8 nm long and about 100 nm diameter, GaAs pillars. They are fabricated with molecular beam epitaxy using a self-assembling method called local droplet etching. The nanopillars are embedded in an AlGaAs tunneling barrier between two epitaxial GaAs layers. Because of the epitaxial growth, the pillars are connected to these GaAs layers without additional interfaces. They thus can be considered as electronic point contacts between three-dimensional electron reservoirs. Voltage-current characteristics of the structures feature a characteristic asymmetry that is not observed in reference samples. Furthermore, the behavior of the resistance in magnetic fields applied parallel and perpendicular to the current direction is compared for samples with and without pillars. Clear differences are found that are associated with current-carrying states in the pillars.     

25-hydroxycholecalciferol serum levels in patients with Crohn's disease

In 37 patients with Crohn's disease the 25-hydroxycholecalciferol (25-HCC) serum level, serum concentration of calcium and inorganic phosphate, and the enzyme activity of alkaline phosphatase were measured. Furthermore the activity index of Crohn's disease was determined in every patient. There was no statistically significant difference of 25-HCC serum levels in these patients compared to a healthy control group. Correspondingly most patients showed normal alkaline phosphatase enzyme activity and normal serum concentration of calcium and inorganic phosphate. No correlation between 25-HCC concentration and site of inflammation or activity index was found.     

A CMOS Low-Noise Instrumentation Amplifier Using Chopper Modulation

This paper describes a low-power, low-noise chopper stabilized CMOS instrumentation amplifier for biomedical applications. Low thermal noise is achieved by employing MOSTs biased in the weak/moderate inversion region, whereas chopper stabilization is utilized to shift 1/f-noise out of the signal band hereby ensuring overall low noise performance. The resulting equivalent input referred noise is approximately 7 nV/ ?{Hz}\sqrt{\rm Hz} for a chopping frequency of 20 kHz. The amplifier operates from a modest supply voltage of 1.8 V, drawing 136 A of current thus consuming 245 W of power. The gain is 72.5 dB over a 4 kHz bandwidth. The inband PSRR is above 90 and the CMRR exceeds 105 dB.     

Cre-loxP-mediated inactivation of the alpha6A integrin splice variant in vivo: evidence for a specific functional role of alpha6A in lymphocyte migration but not in heart development

Two splice variants of the alpha6 integrin subunit, alpha6A and alpha6B, with different cytoplasmic domains, have previously been described. While alpha6B is expressed throughout the development of the mouse, the expression of alpha6A begins at 8.5 days post coitum and is initially restricted to the myocardium. Later in ontogeny, alpha6A is found in various epithelia and in certain cells of the immune system. In this study, we have investigated the function of alpha6A in vivo by generating knockout mice deficient for this splice variant. The Cre- loxP system of the bacteriophage P1 was used to specifically remove the exon encoding the cytoplasmic domain of alpha6A in embryonic stem cells, and the deletion resulted in the expression of alpha6B in all tissues that normally express alpha6A. We show that alpha6A-/- mice develop normally and are fertile. The substitution of alpha6A by alpha6B does not impair the development and function of the heart, hemidesmosome formation in the epidermis, or keratinocyte migration. Furthermore, T cells differentiated normally in alpha6A-/- mice. However, the substitution of alpha6A by alpha6B leads to a decrease in the migration of lymphocytes through laminin-coated Transwell filters and to a reduction of the number of T cells isolated from the peripheral and mesenteric lymph nodes. Lymphocyte homing to the lymph nodes, which involves various types of integrin-ligand interactions, was not affected in the alpha6A knockout mice, indicating that the reduced number of lymph node cells could not be directly attributed to defects in lymphocyte trafficking. Nevertheless, the expression of alpha6A might be necessary for optimal lymphocyte migration on laminin in certain pathological conditions.     

The impact of peptic ulcer disease and infection with Helicobacter pylori on life expectancy

OBJECTIVE: Knowledge about the influence of H. pylori-related disease on life expectancy might affect physician behavior in dealing with such disease. The aim of this study was to assess how life expectancy is influenced by H. pylori infection and peptic ulcer disease. METHODS: The declining exponential approximation of life expectancy was used to model the effects of H. pylori and various peptic ulcer disease conditions on life expectancy. Deaths from peptic ulcer and gastric cancer were determined from the Vital Statistics of the United States. H. pylori prevalence rates were derived from the existing literature. RESULTS: Cure of active peptic ulcer increases life expectancy by 2.3 yr in persons aged 40-44 yr and 121 days in persons aged 70-74 yr. More substantial impact occurs in complicated ulcer, with increases in life expectancy ranging between 26.1 and 6.3 yr. Primary prevention of H. pylori could increase life expectancy by 190 days in those aged 40-44 yr and 26 days in 70-74-yr-old subjects. CONCLUSION: The benefit of ulcer cure or H. pylori prevention diminishes as age advances. Cure of ulcers in young patients or in those who have sustained complications results in an appreciable increase in life expectancy. Successful primary prevention of H. pylori in selected populations could substantially increase life expectancy.     

Comparative cost-effectiveness analysis of theophylline and ipratropium bromide in chronic obstructive pulmonary disease. A three-center study

The charts of 311 patients receiving theophylline (T) and 289 patients receiving ipratropium bromide (IB) for COPD were reviewed to determine the total costs and cost-effectiveness of these 2 agents in 3 different health-care settings. A direct cost-accounting method assessed cost, and a Markov decision-analysis model calculated cost-effectiveness. Costs to treat toxic effects were greater for T versus IB. The types and incidences of toxic effects, by drug, were similar among the three centers. Overall costs for T were $121.40 per patient per therapy-month versus $84.56 per patient per therapy-month for IB, as determined by the cost-accounting method. The marginal cost was $366 for T over IB when extrapolated over 1 year using the Markov model. The Markov model also predicted that patients receiving IB had a greater number of complication-free therapy-months (measurement of effectiveness) than patients receiving T. We conclude that treatment with IB was less costly and more cost-effective than T.     

Influence of vacuum on the porosity and mechanical properties in rotational molding

Rotational molding allows the production of seamless, hollow parts with a high degree of design flexibility. Nevertheless, the process has limitations such as long cycle times as long holding times are necessary to produce components free of air inclusions. Within the scope of this article, an experimental setup was developed to evaluate the possibility and resulting effects of using vacuum in the rotational molding process. For this purpose, trials with different vacuum pressure levels and holding times were carried out and the resulting porosity and surface quality as well as the mechanical properties of the specimens were determined. The investigations showed that the use of vacuum allows a significant reduction in porosity even at low holding times, which can considerably reduce the cycle time of the process. However, the extent of possible time saving is limited by the requirement of a good surface quality, on which the vacuum application shows no effect. Furthermore, the mechanical properties of the parts could be slightly improved by using vacuum. POLYM. ENG. SCI., 59:1544–1551 2019. © 2019 Society of Plastics Engineers     

Collaborating with Virtual Assistants in Organizations: Analyzing Social Loafing Tendencies and Responsibility Attribution

Information Systems Frontiers - Organizations increasingly introduce collaborative technologies in form of virtual assistants (VAs) to save valuable resources, especially when employees are...