302 research outputs found
Oxygen vacancies in strained SrTiO thin films: formation enthalpy and manipulation
We report the enthalpy of oxygen vacancy formation in thin films of
electron-doped SrTiO, under different degrees of epitaxial stress. We
demonstrate that both compressive and tensile strain decrease this energy at a
very similar rate, and promote the formation of stable doubly ionized oxygen
vacancies. Moreover, we also show that unintentional cationic vacancies
introduced under typical growth conditions, produce a characteristic rotation
pattern of TiO octahedra. The local concentration of oxygen vacancies can
be modulated by an electric field with an AFM tip, changing not only the local
electrical potential, but also producing a non-volatile mechanical response
whose sign (up/down) can be reversed by the electric field.Comment: Physical Review B (accepted for publication
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Thiotepa hyperpigmentation preceding epidermal necrosis: malignant intertrigo misdiagnosed as Stevens-Johnson syndrome-toxic epidermal necrolysis overlap
Thiotepa is a common alkylating agent known to precipitate cutaneous reactions consistent with toxic erythema of chemotherapy, including erythema and hyperpigmentation. Herein, we describe an atypical case of malignant intertrigo involving preferential erythema and desquamation not only of skin folds but also of occluded areas after thiotepa-based conditioning. The diagnosis was complicated by concurrent stomatitis and oral petechiae in the setting of autologous stem cell transplant 11 days prior for diffuse large B-cell lymphoma. Histopathological examination from two cutaneous sites demonstrated epidermal dysmaturation and eccrine gland necrosis consistent with thiotepa-induced desquamation and not Stevens-Johnson syndrome or graft-versus-host-disease. Malignant intertrigo can present with extensive cutaneous involvement, as evidenced by our patient who had 25% body surface area affected. Mucosal involvement is common with most chemotherapeutic regimens and its presence should not deter the astute clinician from consideration of a diagnosis of toxic erythema of chemotherapy. No further interventions were needed and the patient healed spontaneously
Electron degeneracy and intrinsic magnetic properties of epitaxial Nb:SrTiO thin-films controlled by defects
We report thermoelectric power experiments in e-doped thin films of SrTiO
(STO) which demonstrate that the electronic band degeneracy can be lifted
through defect management during growth. We show that even small amounts of
cationic vacancies, combined with epitaxial stress, produce a homogeneous
tetragonal distortion of the films, resulting in a Kondo-like resistance upturn
at low temperature, large anisotropic magnetoresistance, and non-linear Hall
effect. Ab-initio calculations confirm a different occupation of each band
depending on the degree of tetragonal distortion. The phenomenology reported in
this paper for tetragonally distorted e-doped STO thin films, is similarto that
observed in LaAlO/STO interfaces and magnetic STO quantum wells.Comment: 5 pages, 5 figure
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The Concept of Rebelliosness of Negroes and Whites
The problem investigated in this paper is the concept of rebelliousness, especially as it applies to two racial groups, Negroes and Whites
Reduction of thermal conductivity in ferroelectric SrTiO3 thin films
Bulk SrTiO3 is a quantum paraelectric in which an antiferrodistortive distortion below approximate to 105 K and quantum fluctuations at low temperature preclude the stabilization of a long-range ferroelectric state. However, biaxial mechanical stress, impurity doping, and Sr nonstoichiometry, among other mechanisms, are able to stabilize a ferroelectric or relaxor ferroelectric state at room temperature, which develops into a longer-range ferroelectric state below 250 K. In this paper, we show that epitaxial SrTiO3 thin films grown under tensile strain on DyScO3 exhibit a large reduction of thermal conductivity, approximate to 60% of at room temperature, with respect to identical strain-free or compressed films. The thermal conductivity shows a further reduction below 250 K, a temperature concurrent with the peak in the dielectric constant [J. H. Haeni et al., Nature (London) 430, 758 (2004)]. These results suggest that strain gradients in the relaxor and ferroelectric phase of SrTiO3 are very effective phonon scatterers, limiting the thermal transport in this material
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Corrigendum: Thiotepa hyperpigmentation preceding epidermal necrosis: malignant intertrigo misdiagnosed as Stevens-Johnson syndrome-toxic epidermal necrolysis overlap
The original article was published on February 15, 2020 and corrected on March 15, 2020.The revised version of the article corrects the contact information of the Corresponding Author. The changes appear in the revised online PDF copy of this article
The Impact of a Complement-Based Assortment Organization on Purchases
This article examines whether and why organizing product categories according to the consumption goal they serve (i.e., complement-based assortment organization) may increase purchases compared with organizing product categories according to their attributes or physical characteristics (i.e., substitute-based assortment organization). Across two field experiments, a virtual reality experiment, and a lab experiment, the authors show that a complement-based assortment organization, compared with a substitute-based assortment organization, leads to increased numbers of purchases and increased expenditures. Ease of visualization of the consumption process mediates the results. The impact of the complement-based organization on purchases is more pronounced for less involved consumers and for consumers with a less specific shopping goal. These findings have both theoretical and practical implications
B-cell activating factor (BAFF) plasma level at the time of chronic GvHD diagnosis is a potential predictor of non-relapse mortality
Biological markers for risk stratification of chronic GvHD (cGvHD) could improve the care of patients undergoing allogeneic hematopoietic stem cell transplantation. Increased plasma levels of B-cell activating factor (BAFF), chemokine (C-X-C motif) ligand 9 (CXCL9) and elafin have been associated with the diagnosis, but not with outcome in patients with cGvHD. We evaluated the association between levels of these soluble proteins, measured by ELISA at the time of cGvHD diagnosis and before the initiation of therapy, with non-relapse-mortality (NRM). Based on the log-transformed values, factor levels were divided into tertiles defined respectively as low, intermediate, and high levels. On univariable analysis, BAFF levels were significantly associated with NRM, whereas CXCL9 and elafin levels were not. Both low (⩽2.3 ng/mL, hazard ratio (HR)=5.8, P=0.03) and high (>5.7 ng/mL, HR=5.4, P=0.03) BAFF levels were associated with a significantly higher NRM compared with intermediate BAFF level. The significant effect of high or low BAFF levels persisted in multivariable analysis. A subset of cGvHD patients had persistently low BAFF levels. In conclusion, our data show that BAFF levels at the time of cGvHD diagnosis are associated with NRM, and also are potentially useful for risk stratification. These results warrant confirmation in larger studies
The biocompatibility of titanium in a buffer solution: compared effects of a thin film of TiO2 deposited by MOCVD and of collagen deposited from a gel
This study aims at evaluating the biocompatibility of titanium surfaces modified according two different ways: (i) deposition of a bio-inert, thin film of rutile TiO2 by chemical vapour deposition (MOCVD), and (ii) biochemical treatment with collagen gel, in order to obtain a bio-interactive coating. Behind the comparison is the idea that either the bio-inert or the bio-active coating has specific advantages when applied to implant treatment, such as the low price of the collagen treatment for instance. The stability in buffer solution was evaluated by open circuit potential (OCP) for medium time and cyclic voltametry. The OCP stabilized after 5104 min for all the specimens except the collagen treated sample which presented a stable OCP from the first minutes. MOCVD treated samples stabilized to more electropositive values. Numeric results were statistically analysed to obtain the regression equations for long time predictable evolution. The corrosion parameters determined from cyclic curves revealed that the MOCVD treatment is an efficient way to improve corrosion resistance. Human dermal fibroblasts were selected for cell culture tests, taking into account that these cells are present in all bio-interfaces, being the main cellular type of connective tissue. The cells grew on either type of surface without phenotype modification. From the reduction of yellow, water-soluble 3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT cytotoxicity test), MOCVD treated samples offer better viability than mechanically polished Ti and collagen treated samples as well. Cell spreading, as evaluated from microscope images processed by the program Sigma Scan, showed also enhancement upon surface modification. Depending on the experimental conditions, MOCVD deposited TiO2 exhibits different nanostructures that may influence biological behaviour. The results demonstrate the capacity of integration in simulated physiologic liquids for an implant pretreated by either method
On the Convergence of Kergin and Hakopian Interpolants at Leja Sequences for the Disk
We prove that Kergin interpolation polynomials and Hakopian interpolation
polynomials at the points of a Leja sequence for the unit disk of a
sufficiently smooth function in a neighbourhood of converge uniformly
to on . Moreover, when is on , all the derivatives of
the interpolation polynomials converge uniformly to the corresponding
derivatives of
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