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Free-standing nanowires are promising platforms for hosting three-dimensional heterostructures such as single quantum dots for quantum photonics, modulation doped heterostructures for gate-all-around high mobility transistors, etc. The peculiarity of heteroepitaxy in nanowires is the existence of multiple growth interfaces with different crystallographic orientations (usually one top- and six side-facets), where the growth can take place in different modes (e.g. vapor-liquid-solid on the top- and vapor-solid on the side-facets) and can be controlled independently. Furthermore, strained epilayers in nanowires can relax elastically both at the lateral free surface and by stretching the substrate, which in this case are the thin nanowires. All these features open up new possibilities for complex three-dimensional heterostructures with loose strain restrictions. Here, we have investigated the growth of radial and axial heterostructures, as well as combinations of the two, within III-As nanowires. The radial ones consist of thin GaAs nanowires overgrown all-around with an InxAl1-xAs layer in a core/shell fashion. In agreement with theory, the small volume of the core allows for strain engineering both in the core and the shell, and for realization of highly-mismatched/strained heterostructures (with misfits up to 4%) without dislocations. The manipulation of the growth kinetics is necessary in order to suppress strain-driven phenomena, such as the preferential shell-growth and In-incorporation on one side of the core. The axial heterostructures consist of single or multiple GaAs/AlxGa1-xAs quantum dots. The width and the thickness of these dots can be controlled independently. The AlxGa1-xAs segments were grown as digital alloys using pulsed epitaxy in order to achieve sharper interfaces and to avoid the formation of stacking faults. Finally, we realized complex heterostructures with single GaAs/AlxGa1-xAs quantum dots inside the core of core/shell nanowires, aiming at engineering the electronic properties of the dots depending on the composition and thickness of the shell. Besides MBE experiments, our investigations involved transmission electron microscopy (HR-TEM, STEM, EDX, STEM tomography), X-ray diffraction, Raman scattering spectroscopy, and photoluminescence spectroscopy.

Single quantum dots in the core of freestanding semiconductor nanowires is a promising scheme for the realization of on-demand sources of single photons or entangled photon pairs in quantum technology systems. Here, we demonstrate that complex quantum-dots can be grown in self-catalyzed III-As nanowires and their emission can be tuned in a wide range of wavelengths. The quantum dots are formed inside self-catalyzed GaAs nanowires (grown on Si substrates by molecular beam epitaxy) by first growing an axial AlxGa1-xAs/GaAs/AlxGa1-xAs heterostructure in pulsed mode . The AlxGa1-xAs segments are grown as digital alloys with a precise control of the composition, the thickness, and the crystal structure (absence of stacking faults). Then, the nanowires are overgrown all-around with an InxAl1-xAs layer in a core/shell fashion. Owing to the large lattice-mismatch with the shell, the thin core develops tensile hydrostatic strain and the emission from the dot is strongly red-shifted. Furthermore, distinct exciton-biexciton features are identified in photoluminescence measurements.

Based on several randomised clinical studies indicating benefit from oral probiotic intake for the prevention of hospital-acquired infections in critically ill patients, this study aimed to explain the mechanism of action of probiotics for the prevention of lethal experimental infection by multidrug-resistant (MDR) Pseudomonas aeruginosa. Experiments using an Escherichia coli strain susceptible to all antimicrobials were also conducted. C57BL/6 mice were pre-treated intraperitoneally with sterile water for injection or Lactobacillus plantarum. Survival was recorded and mice were sacrificed for measurement of apoptosis and tissue bacterial overgrowth and for isolation and culture of splenocytes for cytokine production. Experiments were repeated after pre-treatment with a commercial preparation of four probiotics (L. plantarum, Lactobacillus acidophilus, Saccharomyces boulardii and Bifidobacterium lactis; LactoLevure®). Peripheral blood mononuclear cells (PBMCs) of healthy volunteers were stimulated by heat-killed P. aeruginosa following pre-treatment with medium or probiotics. Pre-treatment with L. plantarum significantly prolonged survival after challenge by either MDR P. aeruginosa (66.7% vs. 31.3%; P = 0.026) or E. coli (56.0% vs. 12.0%, P = 0.003). Survival benefit was even more pronounced when mice were pre-treated with LactoLevure®. Tissue bacterial outgrowth and apoptosis of white blood cells and splenocytes were not altered. TNFα and IL-10 production by splenocytes of mice pre-treated with probiotic was increased and IFNγ production was decreased. Pre-treatment with LactoLevure® restored production of IL-17. Stimulation of human PBMCs after probiotic pre-treatment was accompanied by reduced gene expression of SOCS3. The results suggest that the protective effect of probiotics is mediated through prevention of sepsis-induced immunosuppression. © 2015 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Objective: Previous few studies have shown that resistin is significantly elevated in breast cancer (BC) patients. Therefore, we investigated whether serum resistin could be used as a potential diagnostic and prognostic tool for postmenopausal BC (PBC), taking into account clinicopathological features, serum tumor markers, anthropometric, metabolic, and, for the first time, inflammatory parameters. Methods: Serum resistin, tumor markers (CA 15-3 and CEA), metabolic, anthropometric and inflammatory parameters (TNF-α, IL-6, hsCRP) were determined in 103 postmenopausal women with incident, pathologically confirmed, invasive BC, 103 controls matched on age and time of diagnosis, and 51 patients with benign breast lesions (BBL). Results: Mean serum resistin was significantly higher in cases than in controls and patients with BBL (p

Objective: Previous studies have shown that visfatin is significantly elevated in patients with gastric carcinoma and postmenopausal breast cancer (PBC). We thus explored whether serum visfatin could be used as a potential diagnostic and prognostic tool for PBC, taking into account clinicopathological features, serum tumor markers, anthropometric and metabolic parameters. Methods: Serum visfatin, tumor marker CA 15-3, carcinoembryonic antigen, metabolic and anthropometric parameters were determined in 103 postmenopausal women with pathologically confirmed, incident invasive breast cancer, 103 controls matched on age and time of diagnosis, and 51 patients with benign breast lesions (BBL). Results: Mean serum visfatin was significantly higher in cases than in controls and patients with BBL (p < 0.001). In cases, visfatin was significantly associated with CA 15-3 (p = 0.03), hormone-receptor status (p < 0.001), lymph node invasion (p = 0.06) but not with metabolic and anthropometric variables (p > 0.05). Multivariable regression analysis revealed that absence of estrogen and progesterone receptors (ER-PR-) was the strongest significant determinant of serum visfatin (p < 0.001) in cases adjusting for demographic, metabolic and clinicopathological features. Based upon receiver operator characteristic analysis, serum visfatin outperformed CA 15-3 only in discriminating between PBC cases with early cancer stage than those with late stage, and in differentiating particularly patients with ER-PR- breast tumors. Conclusion: Further prospective and longitudinal studies are needed to determine whether serum visfatin could be used as a prognostic tool in the armamentarium of PBC monitoring and management in conjunction with other biomarkers. © 2011 Elsevier Ireland Ltd. All rights reserved.

Objective: Obesity has been implicated in the etiology of postmenopausal breast cancer (PBC). We hypothesized that altered secretion of visfatin may underlie this association. We thus investigated the association of serum visfatin with PBC risk, taking into account known risk factors including adipokines and anthropometric and metabolic parameters. Methods: In a case-control study, we studied 102 postmenopausal women with pathologically confirmed, incident invasive breast cancer and 102 control women matched on age and time of diagnosis between 2003 and 2010 at Army Share Fund Hospital, Veterans' Hospital (NIMTS). Levels of serum visfatin, adiponectin, leptin, metabolic parameters, carcinoembryonic antigen, and CA 15-3 were determined. Results: The mean serum visfatin level was significantly higher in case than in control participants (P < 0.001). Women in the highest quartile of visfatin concentration presented significantly higher odds for PBC, adjusting for age, date of diagnosis, education, body mass index, waist circumference, years with menstruation, parity/age at first full-term pregnancy, breast-feeding, family history of cancer, use of exogenous hormones, alcohol consumption, smoking status, homeostasis model assessment score, and serum leptin and adiponectin concentrations (odds ratio, 7.93; 95% CI, 2.52-24.9). In case participants, the visfatin level correlated significantly with the tumor marker CA 15-3 (P = 0.03) but not with metabolic and anthropometric variables (P > 0.05). Conclusions: Further prospective studies are needed to determine whether an elevated serum visfatin level is implicated in the etiopathogenesis of PBC or reflects changes during PBC progression and could therefore be used as a biomarker for PBC. © 2011 The North American Menopause Society.

Background: The pandemic by the novel H1N1 virus has created the need to study any probable effects of that infection in the immune system of the host. Methodology/Principal Findings: Blood was sampled within the first two days of the presentation of signs of infection from 10 healthy volunteers; from 18 cases of flu-like syndrome; and from 31 cases of infection by H1N1 confirmed by reverse RT-PCR Absolute counts of subtypes of monocytes and of lymphocytes were determined after staining with monoclonal antibodies and analysis by flow cytometry. Peripheral blood mononuclear cells (PBMCs) were isolated from patients and stimulated with various bacterial stimuli. Concentrations of tumour necrosis factor-alpha, interleukin (IL)-1beta, IL-6, IL-18, interferon (FN)-alpha and of IFN-gamma were estimated in supernatants by an enzyme immunoassay. Infection by H1N1 was accompanied by an increase of monocytes. PBMCs of patients evoked strong cytokine production after stimulation with most of bacterial stimuli. Defective cytokine responses were shown in response to stimulation with phytohemagglutin and with heat-killed Streptococcus pneumoniae. Adaptive immune responses of H1N1-infected patients were characterized by decreases of CD4-lymphocytes and of B-lymphocytes and by increase of T-regulatory lymphocytes (Tregs). Conclusions/Significance: Infection by the H1N1 virus is accompanied by a characteristic impairment of the innate immune responses characterized by defective cytokine responses to S.pneumoniae. Alterations of the adaptive immune responses are predominated by increase of Tregs. These findings signify a predisposition for pneumococcal infections after infection by H1N1 influenza.©2009 Giamarellos-Bourboulis et al.

A one dimensional (1D) transfer matrix calculation of current transport in semiconductor nanowires with built-in barriers is described within the effective mass approximation by taking into account (i) the quantum confinement in the radial direction and (ii) the Fermi level position with respect to the 1D sub-band(s), both of which can be determined analytically. We calculate the current-voltage (I-V) characteristic for an InAs nanowire, which has a radius of 200 Å and two 50 Å InP, built-in barriers, which define a 150 Å long InAs quantum disk and find that a peak in the current occurs at an applied voltage of 72 mV, corresponding to resonant tunneling of carriers through the double barriers. This is in good agreement with the I-V curve measured in a similar nanowire at a temperature of 4.2 K, where resonant tunneling occurs at 80 mV. It is deduced that the Fermi level is ≈26 meV above the conduction band edge at the surface of the specific InAs nanowire, which is ten times lower than the Fermi level pinning at inverted InAs thin film surfaces. We discuss the importance of the strain and surface depletion. © 2008 American Institute of Physics. 104

A theoretical investigation of the effect of polarization-induced fields on the optoelectronic properties of a 3 nm In0.2Ga0.8N/GaN single quantum well has been carried out via a self-consistent solution of Schrödinger-Poisson equations within the effective mass approximation. A pronounced, non-monotonic dependence of the threshold current density Jth on the well width has been found due to the enhanced quantum-confined Stark effect. Furthermore, the dependence of threshold current density on the value of the electric field in the well was examined. The threshold current in the 3 nm In0.2Ga0.8N/GaN well is higher by a factor of 2-5 compared to an identical well with zero internal field Eint. We show that the ability to reduce or eliminate internal fields appears attractive for the improvement of the optoelectronic properties of nitride-based laser diodes and one of achieving this is by using field-compensated quaternary InAlGaN/GaN heterostructures. © 2006 Elsevier B.V. All rights reserved. 32 558 561 558-561

We show that residual doping and carrier distribution effects decrease the observed polarization-induced electric fields in GaN/AlGaN quantum wells and that these effects ought to be considered if we want to compare in a meaningful manner the experimental and theoretical polarizations in the AlGaN system. 188 867 870 867-870

We report early experimental results demonstrating a novel all-optical piezoelectric-barrier quantum well (QW) modulator. The device is designed such that an incident control laser beam strongly modulates the ground slate QW resonance of the heterostructure. Essential to this design is the fact that in strained semiconductor heterostructures grown along a polar axis (in our case [211]), the lattice-mismatch induced strain generates a large piezoelectric field along the growth axis [1].