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We report different growth modes and corresponding magnetic properties of thin EuSe films grown by molecular beam epitaxy on BaF2, Pb1−xEuxSe, GaAs, and Bi2Se3 substrates. We show that EuSe grows predominantly in the (001) orientation on GaAs(111) and Bi2Se3, but along the (111) crystallographic direction on BaF2 (111) and Pb1−xEuxSe (111). High resolution transmission electron microscopy measurements reveal a sharp and highly crystalline interface for both (001) and (111) EuSe films. In agreement with previous studies, ordered magnetic phases include antiferromagnetic, ferrimagnetic, and ferromagnetic phases. In contrast to previous studies, we found a strong hysteresis of the antiferromagnetic–ferrimagnetic transition. The ability to grow epitaxial films of EuSe on Bi2Se3 and of Bi2Se3 on EuSe enables further investigation of interfacial exchange interactions between various phases of an insulating metamagnetic material and a topological insulator. [ABSTRACT FROM AUTHOR]

Topological surface-states can acquire an energy gap when time-reversal symmetry is broken by interfacing with a magnetic insulator. This gap has yet to be measured. Such topological-magnetic insulator heterostructures can host a quantized anomalous Hall effect and can allow the control of the magnetic state of the insulator in a spintronic device. In this work, we observe the energy gap of topological surface-states in proximity to a magnetic insulator using magnetooptical Landau level spectroscopy. We measure Pb1-xSnxSe–EuSe heterostructures grown by molecular beam epitaxy exhibiting a record mobility and low Fermi energy. Through temperature dependent measurements and theoretical calculations, we show this gap is likely due to quantum confinement and conclude that the magnetic proximity effect is weak in this system. This weakness is disadvantageous for the realization of the quantum anomalous Hall effect, but favorable for spintronic devices which require the preservation of spin-momentum locking at the Fermi level. The proximity coupling of topological insulators with magnetic materials can give rise to exotic phenomenon such as the quantum anomalous Hall effect. Here, the authors use magneto-optical Landau level spectroscopy to investigate Pb1-xSnxSe-EuSe heterostructures finding evidence of a quantum confinement induced energy gaps in the topological surface states, that overshadow the magnetic proximity effects. [ABSTRACT FROM AUTHOR]

This report showcases a vertical tunnel field effect transistor (TFET) fabricated from a GaN/InGaN heterostructure and compares it to a gated vertical GaN p-n diode. By including a thin InGaN layer, the interband tunneling in the TFET is increased compared to the gated homojunction diode. This leads to an increased drain current of 57 μA/μm and a reduced subthreshold swing of 102 mV/dec, from 240 mV/dec. However, trap assisted tunneling prevents devices from realizing subthreshold slopes below the Boltzmann limit of 60 mV/dec. Nevertheless, this work shows the capability of tunnel field effect transistors to be realized in GaN by taking advantage of the spontaneous and piezoelectric polarization in the III-N material system. [ABSTRACT FROM AUTHOR]

A novel method for fabricating metal-based single-electron transistors (SETs) is reported that combines a nanoscale island produced via electron beam induced deposition (EBID) of Pt metal with a tunnel barrier dielectric produced via atomic layer deposition (ALD) of alumina (Al2O3). A characteristic nonlinearity in Ids-Vds and Coulomb blockade oscillations of the SET are observed at 300 mK. The versatility of the EBID method provides a way to fabricate 3D structures that could be particularly useful in a number of charge sensing applications and which, combined with the accuracy and precise control that ALD provides for the SET's tunnel barriers, greatly expands the choice of techniques suitable for SET fabrication. [ABSTRACT FROM AUTHOR]

The response to steroid therapy is used to characterize the idiopathic nephrotic syndrome (INS) of childhood as either steroid-sensitive (SSNS) or steroid-resistant (SRNS), a classification with a better prognostic capability than renal biopsy. The majority (∼80%) of INS is due to minimal change disease but the percentage of focal and segmental glomerulosclerosis is increasing. We applied a new technological platform to examine the urine proteome to determine if different urinary protein excretion profiles could differentiate patients with SSNS from those with SRNS. Twenty-five patients with INS and 17 control patients were studied. Mid-stream urines were analyzed using surface enhanced laser desorption and ionization mass spectrometry(SELDI-MS). Data were analyzed using multiple bioinformatic techniques. Patient classification was performed using Biomarker Pattern SoftwareTM and a generalized form of Adaboost and predictive models were generated using a supervised algorithm with cross-validation. Urinary proteomic data distinguished INS patients from control patients, irrespective of steroid response, with a sensitivity of 92.3%, specificity of 93.7%, positive predictive value of 96% and a negative predictive value of 88.2%. Classification of patients as SSNS or SRNS was 100%. A protein of mass 4,144 daltons was identified as the single most important classifier in distinguishing SSNS from SRNS. SELDI-MS combined with bioinformatics can identify different proteomic patterns in INS. Characterization of the proteins of interest identified by this proteomic approach with prospective clinical validation may yield a valuable clinical tool for the non-invasive prediction of treatment response and prognosis. Copyright © 2006 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Interactions of leukocytes with the vascular endothelium culminating in their diapedesis represent not only a crucial event in immune surveillance and defense but are also critically involved in the pathogenesis of many inflammatory diseases, including atherosclerosis. Our previous in vitro studies using atomic force microscopy measurement of monocyte-endothelial cell interaction have demonstrated that a cyclic arginine-glycine-aspartic acid peptide (cRGD) inhibited their adhesion through very late antigen (α4β1-integrin; VLA4)-vascular cell adhesion molecule-i by 60% with the IC50 = 100 nM. To elucidate the potential efficacy of this peptide in vivo in preventing atherogenesis, experiments were performed in apolipoprotein E (ApoE)-deficient (-/-) mice fed a Western diet and receiving chronic treatment with cRGD peptide for 2-4 wk. In addition, some animals were subjected to a temporary carotid artery ligation while receiving the above treatment. Formation of fatty streaks and infiltration of the vascular wall with macrophages were not affected by cRGD treatment. Infiltration of the carotid artery postligation was significantly reduced in the cRGD-treated animals, as was the lipid accumulation. Furthermore, cRGD-treated ApoE-/- mice exhibited significantly lesser macrophage infiltration and lipid accumulation in the kidneys, the site of the highest expression of VLA4, These data demonstrated that cRGD peptide is a potent inhibitor of monocyte/macrophage infiltration of the injured macrovasculature and of the renal microvasculature, where it results in the attenuation of lipid accumulation. Formation of fatty streaks in the aortic root was not inhibitable by this treatment. [ABSTRACT FROM AUTHOR]