Inversion of exciton level splitting in quantum dots

The demonstration of degeneracy of exciton spin states is an important step toward the production of entangled photon pairs from the biexciton cascade. We measure the fine structure of exciton and biexciton states for a large number of single InAs quantum dots in a GaAs matrix; the energetic splitting of the horizontally and vertically polarized components of the exciton doublet is shown to decrease as the exciton confinement decreases, crucially passing through zero and changing sign. Thermal annealing is shown to reduce the exciton confinement, thereby increasing the number of dots with splitting close to zero

Repurposing existing drugs for the treatment of COVID-19

The rapid global spread and significant mortality associated with the coronavirus disease (COVID-19) caused by SARS-CoV-2 viral infection has spurred an urgent race to find effective treatments. Repurposing existing drugs is a particularly attractive approach as pharmacokinetic and safety data already exist, thus development can leapfrog straight to clinical trials of efficacy, generating results far more quickly than de novo drug development. This review summarizes the state of play for the principle drugs identified as candidates to be repurposed for treating COVID-19 grouped by broad mechanism of action: antiviral, immune enhancing, and anti-inflammatory or immunomodulatory. Patient selection, particularly with regard to disease stage, is likely to be key. To date only dexamethasone and remedesivir have been shown to be effective, but several other promising candidates are in trials

Date Fiber as a Constituent of Broiler Starter Diets

In Oman, efforts are underway to find alternative sources of fwd to support domestic livestock. The date industry thrives in Oman and one of its by-products is date fiber, a by-product of date syrup production. Although the product contains some free sugars, an evaluation of its potential in broiler diets has never been undertaken. Therefore, we conducted an experiment to investigate the value of date fiber in broiler chick diets. The experimental diets consisted of four graded levels of date fiber: 0, 15, 30 and 45 % in a broiler-starter ration replacing corn as an energy source. The diets were isonitrogenous. There were five replicates for each of the four diets and each replicate contained six broiler chicks. As date fiber percent increased in the dietary treatment, there were linear reductions in body weight gain, calculated apparent metabolizable energy (AMEn) content, and apparent protein digestibility (P < 0.05). Poor feed utilization (i .e., reduced feed efficiency) was observed in birds fed date fiber diets compared to the control group (P < 0.05). The poor performance of birds fed date fiber may be attributed to protein and energy limitations. We conclude that date fiber has no value in growing broiler diets. However, it may have utility in diets where a stable body weight is desirable

Survey of the Problems of Girl Child in Ekiti State, Nigeria

Objectives: To determine the prevalence of teenage pregnancy and knowledge of reproductive health problems among adolescent girls in Ekiti State, Southwest Nigeria.Methods: A cross-sectional community based study was conducted. Using convenient random sampling technique, four local government areas were selected. Eligible participants were both in and out of school children between the ages of 13 -18 years. A hundred respondents were sampled from each selected local government, making a total sample size of 400. Consenting participants were administered questionnaire in their homes by trained LGA enumerators. It elicited information on socio-demographic and reproductive health issues. Data collected were subsequently collated and analyzed.Results: Majority of the girls (78%) were still in-school. All were already menstruating, mostly attaining menarche between the age 15-16years. Only 212 (53%) could remember their last menstrual period. Sexual derby mainly occurred around age 15-16years; 53.3% were already sexually exposed. A quarter of respondents had been pregnant before. Only 187 (46.8%) were aware of modern contraception. The girls had a fair knowledge of implication of early sexual derby and unprotected intercourse, though it did not translate to behavioural change.Conclusion: There is a high prevalence of teenage pregnancy and poor reproductive health knowledge among teenagers in Ekiti State. More collective efforts involving parents, community heads, opinion leaders, civil societies and the state are needed to help our girls attain and sustain healthy reproductive behaviours

Nanostructured luminescently labeled nucleic acids

Important and emerging trends at the interface of luminescence, nucleic acids and nanotechnology are: (i) the conventional luminescence labeling of nucleic acid nanostructures (e.g. DNA tetrahedron); (ii) the labeling of bulk nucleic acids (e.g. single‐stranded DNA, double‐stranded DNA) with nanostructured luminescent labels (e.g. copper nanoclusters); and (iii) the labeling of nucleic acid nanostructures (e.g. origami DNA) with nanostructured luminescent labels (e.g. silver nanoclusters). This review surveys recent advances in these three different approaches to the generation of nanostructured luminescently labeled nucleic acids, and includes both direct and indirect labeling methods

Bolometric detection of terahertz quantum cascade laser radiation with graphene-plasmonic antenna arrays

We present a fast room temperature terahertz detector based on graphene loaded plasmonic antenna arrays. The antenna elements, which are arranged in series and are shorted by graphene, are contacting source and drain metallic pads, thus providing both the optical resonant element and the electrodes. The distance between the antenna's arms of approximately 300 nm allows a strong field enhancement in the graphene region, when the incident radiation is resonant with the antennas. The current passing through the source and drain is dependent on the graphene's conductivity, which is modified by the power impinging onto the detector as well as from the biasing back-gate voltage. The incident radiation power is thus translated into a current modification, with the main detection mechanism being attributed to the bolometric effect. The device has been characterized and tested with two bound to continuum terahertz quantum cascade lasers emitting at a single frequency around 2 THz and 2.7 THz yielding a maximum responsivity of ~2 mA W$^{−1}$.RD, HEB and DAR acknowledge financial support from the Engineering and Physical Sciences Research Council (Grant No. EP/J017671/1, Coherent Terahertz Systems). SH acknowledges funding from EPSRC (Grant No. EP/K016636/1, GRAPHTED). KN acknowledges the University of Cambridge Nanoscience Doctoral Training Centre (EPSRC EP/G037221/1) for financial support

Zinc Overload Enhances APP Cleavage and Aβ Deposition in the Alzheimer Mouse Brain

BACKGROUND: Abnormal zinc homeostasis is involved in β-amyloid (Aβ) plaque formation and, therefore, the zinc load is a contributing factor in Alzheimer's disease (AD). However, the involvement of zinc in amyloid precursor protein (APP) processing and Aβ deposition has not been well established in AD animal models in vivo. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, APP and presenilin 1 (PS1) double transgenic mice were treated with a high dose of zinc (20 mg/ml ZnSO4 in drinking water). This zinc treatment increased APP expression, enhanced amyloidogenic APP cleavage and Aβ deposition, and impaired spatial learning and memory in the transgenic mice. We further examined the effects of zinc overload on APP processing in SHSY-5Y cells overexpressing human APPsw. The zinc enhancement of APP expression and cleavage was further confirmed in vitro. CONCLUSIONS/SIGNIFICANCE: The present data indicate that excess zinc exposure could be a risk factor for AD pathological processes, and alteration of zinc homeostasis is a potential strategy for the prevention and treatment of AD

Low-energy Pion-nucleon Scattering

This paper contains the results of an analysis of recent low-energy pion-nucleon scattering experiments. Obtained are phase shifts, the pion-nucleon coupling constant and an estimate of the Sigma term.Comment: 30 pages, 11 figures, LaTe