GaAs interfacial self-cleaning by atomic layer deposition

The reduction and removal of surface oxides from GaAs substrates by atomic layer deposition (ALD) of Al2O3 and HfO2 are studied using in situ monochromatic x-ray photoelectron spectroscopy. Using the combination of in situ deposition and analysis techniques, the interfacial "self-cleaning" is shown to be oxidation state dependent as well as metal organic precursor dependent. Thermodynamics, charge balance, and oxygen coordination drive the removal of certain species of surface oxides while allowing others to remain. These factors suggest proper selection of surface treatments and ALD precursors can result in selective interfacial bonding arrangements

Frequency dispersion reduction and bond conversion on n-type GaAs by in situ surface oxide removal and passivation

The method of surface preparation on n-type GaAs, even with the presence of an amorphous-Si interfacial passivation layer, is shown to be a critical step in the removal of accumulation capacitance frequency dispersion. In situ deposition and analysis techniques were used to study different surface preparations, including NH4OH, Si-flux, and atomic hydrogen exposures, as well as Si passivation depositions prior to in situ atomic layer deposition of Al2O3. As–O bonding was removed and a bond conversion process with Si deposition is observed. The accumulation capacitance frequency dispersion was removed only when a Si interlayer and a specific surface clean were combined

Hydrodynamics of topological defects in nematic liquid crystals

We show that back-flow, the coupling between the order parameter and the velocity fields, has a significant effect on the motion of defects in nematic liquid crystals. In particular the defect speed can depend strongly on the topological strength in two dimensions and on the sense of rotation of the director about the core in three dimensions.Comment: 4 pages including two figure

Words fail me: the verbal IQ deficit in inflammatory bowel disease and irritable bowel syndrome

Background: Many chronic illnesses are accompanied by impaired cognitive functioning. In people with Inflammatory Bowel Disease (IBD), there is some research to suggest a decrement in verbal IQ (VIQ), when compared to people with Irritable Bowel Syndrome (IBS) and healthy controls. Although this is an important finding, it is necessary to ensure that such deficits are not due to methodological problems such as the failure to take into account pre-morbid functioning. Methods: A total of 88 people (IBD, N 29; IBS, N 29; Controls, N 30) completed the Wechsler Abbreviated Scale of Intelligence (WASI), the Wechsler Test of Adult Reading (WATR), the Trait Rumination Questionnaire (TRQ), the Center for Epidemiologic Studies Depression Scale (CES-D), and the General Health Questionnaire (GHQ-12). Results: We found evidence of a VIQ decrement in both IBD and IBS groups when measured against both healthy controls and against their own pre-morbid IQ scores (WTAR-Predicted WAIS-III IQ measures). However, the decrement was larger (and of clinical significance) in the IBD group but not in the IBS group. Conclusion: Some tentative evidence is presented which suggests that poor VIQ performance may be due in part to interference from excessive rumination

Galactomannan Does Not Precede Major Signs on a Pulmonary Computerized Tomographic Scan Suggestive of Invasive Aspergillosis in Patients with Hematological Malignancies

Background. Detection of serum galactomannan (GM) antigen and presence of the halo sign on a pulmonary computerized tomographic (CT) scan have a high specificity but a low sensitivity to diagnose invasive aspergillosis (IA) in patients at risk for this disease. To our knowledge, the relationship between the time at which pulmonary infiltrates are detected by CT and the time at which GM antigens are detected by enzyme immunoassay (EIA) has not been studied. Methods. In a prospective study, tests for detection of GM were performed twice weekly for patients with hematological malignancies who had undergone hematopoetic stem cell transplantation (HSCT) or had received induction and/or consolidation chemotherapy. A pulmonary CT scan was performed once weekly. Infiltrates were defined as either major or minor signs. IA was classified as proven, probable, or possible, in accordance with the definition stated by the European Organization for Research and Treatment of Cancer-Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycoses Study Group. Results. We analyzed 161 episodes of infection in 107 patients (65 allogeneic HSCT recipients, 30 autologous HSCT recipients, and 66 induction and/or consolidation chemotherapy recipients). A total of 109 episodes with no IA, 32 episodes with possible IA, and 20 episodes with probable or proven IA were identified. Minor pulmonary signs were detected by CT in 70 episodes (43%), and major pulmonary signs were detected by CT in 11 episodes (7%). Univariate and multivariate analyses revealed no significant association between detection of GM by EIA and detection of abnormal pulmonary signs by CT. A significant association was found between GM levels and receipt of piperacillin-tazobactam. GM test results were not positive before major signs were seen on CT images. Only 7 (10%) of 70 patients with minor pulmonary signs had positive GM test results before detection of the greatest pathologic change by CT. Conclusions. We show that detection of GM by EIA does not precede detection of major lesions by pulmonary CT. In the clinical setting, the decision to administer mold-active treatment should based on detection of new pulmonary infiltrates on CT performed early during infection, rather than on results of EIA for detection of G

THE FREQUENCIES OF HAPTOGLOBIN TYPES IN FIVE POPULATIONS *

Haptoglobin types have been determined by starch gel electrophoresis of blood from five populations. The gene frequencies obtained for allele Hp 1 were as follows: American whites, 043; American Negroes, 0.59; African Negroes, 0.72; Apaches, 0.59; and Asiatic Indians, 0.18. In tribes of the Ivory Coast and Liberia, there was a suggestion of a cline which parallels that for haemoglobin S. Evidence is presented that the condition of ahaptoglobinemia is under genetic control but not by a gene allelic to the Hp 1 -Hp 2 series. The importance of the ahaptoglobinemic individuals for genetic studies and the possibility of selection in the maintenance of the genetic polymorphism are discussed. The authors wish to acknowledge the excellent assistance of Alojzia Sandor, who carried out the electrophoretic separations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66263/1/j.1469-1809.1958.tb01460.x.pd

On the calculation of effective electric field in In0.53Ga0.47As surface channel metal-oxide-semiconductor field-effect-transistors

The effective electron mobility of In0.53Ga0.47As metal-oxide-semiconductor field-effect-transistors with HfO2 gate oxide was measured over a wide range of channel doping concentration. The back bias dependence of effective electron mobility was used to correctly calculate the vertical effective electric field. The effective electron mobility at moderate to high vertical effective electric field shows universal behavior independent of substrate impurity concentration. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3588255

Colloquium: Mechanical formalisms for tissue dynamics

The understanding of morphogenesis in living organisms has been renewed by tremendous progressin experimental techniques that provide access to cell-scale, quantitative information both on theshapes of cells within tissues and on the genes being expressed. This information suggests that ourunderstanding of the respective contributions of gene expression and mechanics, and of their crucialentanglement, will soon leap forward. Biomechanics increasingly benefits from models, which assistthe design and interpretation of experiments, point out the main ingredients and assumptions, andultimately lead to predictions. The newly accessible local information thus calls for a reflectionon how to select suitable classes of mechanical models. We review both mechanical ingredientssuggested by the current knowledge of tissue behaviour, and modelling methods that can helpgenerate a rheological diagram or a constitutive equation. We distinguish cell scale ("intra-cell")and tissue scale ("inter-cell") contributions. We recall the mathematical framework developpedfor continuum materials and explain how to transform a constitutive equation into a set of partialdifferential equations amenable to numerical resolution. We show that when plastic behaviour isrelevant, the dissipation function formalism appears appropriate to generate constitutive equations;its variational nature facilitates numerical implementation, and we discuss adaptations needed in thecase of large deformations. The present article gathers theoretical methods that can readily enhancethe significance of the data to be extracted from recent or future high throughput biomechanicalexperiments.Comment: 33 pages, 20 figures. This version (26 Sept. 2015) contains a few corrections to the published version, all in Appendix D.2 devoted to large deformation

Topological Defects in Nematic Droplets of Hard Spherocylinders

Using computer simulations we investigate the microscopic structure of the singular director field within a nematic droplet. As a theoretical model for nematic liquid crystals we take hard spherocylinders. To induce an overall topological charge, the particles are either confined to a two-dimensional circular cavity with homeotropic boundary or to the surface of a three-dimensional sphere. Both systems exhibit half-integer topological point defects. The isotropic defect core has a radius of the order of one particle length and is surrounded by free-standing density oscillations. The effective interaction between two defects is investigated. All results should be experimentally observable in thin sheets of colloidal liquid crystals.Comment: 13 pages, 16 figures, Phys. Rev.

Differences in anti-malarial activity of 4-aminoalcohol quinoline enantiomers and investigation of the presumed underlying mechanism of action

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