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High pressure spectroscopy is an efficient tool for verifying mechanisms of light emission. In this review high-pressure studies of recombination processes in InGaN alloys and quantum well (QW) structures: GaN/AlN, GaN/AlGaN, and near-lattice-matched GaN/AlInN are presented. The radiative recombination in nitride alloys corresponds to band-to-band transitions, thus the pressure coefficient of the photoluminescence energy dEPL/dp corresponds approximately to the pressure coefficient of the energy gap dEG/dp. In nitride polar heterostructures the built-in electric field influences strongly radiative recombination processes inducing a red shift of the photoluminescence energy. It is described by the quantum-confined Stark effect (QCSE). Applying pressure causes an increase of the electric field and consequently a decrease of dEPL/dp with respect to dEG/dp. It is also shown that dEG/dp is strongly reduced with increasing QW width. It reflects an increase in the effect of built-in electric field originating from more pronounced QCSE in wider QWs. [ABSTRACT FROM AUTHOR]

Bandgaps of AlInN alloys, short‐period InN/AlN superlattices (SLs), and short‐period AlInN alloy SLs are calculated using first‐principles calculations with the pseudopotential self‐interaction correction method. The dependence of these bandgaps on the composition and thickness of the SLs and the influence of strain are investigated. It is found that the bandgaps of the InN/AlN SLs depend on both the composition and thickness of the SLs. The maximum value of the bandgap equal to 2.56 eV is obtained for 1InN/4AlN SLs. The bandgaps of AlInN alloy SLs decrease with an increase in In content, and they cover the whole range between the values of AlN and InN. The bandgaps of InN/AlN SLs lattice‐matched to AlN are smaller than those of free‐standing InN/AlN SLs. [ABSTRACT FROM AUTHOR]

There is an increased risk of stroke in patients with HIV infection. One of the mechanisms is production of anticardiolipin (aCL) antibodies, induced by the virus. Many studies have documented a high incidence of aCL antibodies in patients with HIV infection and the increased risk of stroke, although there is no such correlation with other viruses that also stimulate production of aCL antibodies. Probably the HIV virus also stimulates production of other serum proteins, which together with aCL antibodies make procoaqulation complexes, similar to the primary anticardiolipin syndrome. We present a case of a 40-year-old patient, hospitalized three times in our department because of recurrent ischemic strokes. Diagnostic tests revealed a high titre of anticardiolipin antibodies and the early stage of HIV infection. Recurrent ischemic strokes were the first manifestation of HIV infection in this patient. [ABSTRACT FROM AUTHOR]

The article offers information on the Eight International Workshop on Nitride Semiconductors (IWN 2014) to be held in Wrocław, Poland from August 24-29, 2015.

Since a few years, attempts are taken at the application of vagus nerve stimulation in the treatment of severe depression. It appears that the vagus nerve exerts a direct influence on areas of the brain associated with the regulation of mood and increases the level of biogenic amines. What is more, studies have confirmed an increased activity of fronto-orbital and prefrontal cortex, hypothalamus, cingulum and an increased concentration of serotonin and noradrenalin in the CNS and in the cerebro-spinal fluid. Preliminary clinical trials have confirmed the efficacy, good tolerance and safety of this treatment modality, although some objections have been raised whether these promising results were not partly due to the placebo effect. Therefore new, multicenter clinical studies have been designed, enabling an unbiased evaluation of usefulness of this method in the treatment of depression.