Dilute magnetic semiconductor quantum-well structures for magnetic field tunable far-infrared/terahertz absorption

The design of ZnCdSe–ZnMnSe-based quantum wells is considered, in order to obtain a large shift of the peak absorption wavelength in the far infrared range, due to a giant Zeeman splitting with magnetic field, while maintaining a reasonably large value of peak absorption. A triple quantum-well structure with a suitable choice of parameters has been found to satisfy such requirements. A maximal tuning range between 14.6 and 34.7 meV is obtained, when the magnetic field varies from zero to 5 T, so the wavelength of the absorbed radiation decreases from 85.2 to 35.7 μm with absorption up to 1.25% at low temperatures. These structures might form the basis for magnetic field tunable photodetectors and quantum cascade lasers in the terahertz range

Interplay between mesoscopic phase separation and bulk magnetism in the layered NaxCoO2

Specific heat of the layered NaxCoO2 (x=0.65, 0.70 and 0.75) oxides has been measured in the temperature range of 3-360 K and magnetic field of 0 and 9 T. The analysis of data, assuming the combined effect of inter-layer superexchange and the phase separation into mesoscopic magnetic domains with localized spins embedded in a matrix with itinerant electronic character, suggests that the dominant contribution to the specific heat in the region of short-range ordering is mediated by quasi-2D antiferromagnetic clusters, perpendicular to the CoO2 layers

Innovation and external knowledge sources in knowledge intensive business services (KIBS): evidence from de-industrialized UK regions

This paper explores the effect of external knowledge sources and the uneven geography on innovation activity in small Knowledge Intensive Business Services (KIBS). It draws on results from a survey of 342 small and medium (SME) KIBS located in the UK’s North East and West Midlands, both de-industrialised regions. It is shown that innovation is supported by knowledge gained from frequent interaction with customers both regional and UK based as well as international. More frequent interaction with local business networks, informal contacts and national licensing arrangements also enhances innovativeness. Various industry-specific business networks and regional government agencies act as important sources of knowledge and networking and these are more important for KIBS located in the North East. The results indicate that more frequent collaboration with regional universities and regional public sector organisations does not benefit KIBS from either region. Also, while we acknowledge a positive effect of R&D on KIBS innovativeness we argue that its effect is less important compared to regional and extra regional knowledge sources

The effect of external knowledge sources and their geography on innovation in Knowledge Intensive Business Services (KIBS) SMEs; some Implications for de-industrialized regions in the UK

The paper explores the effect of external knowledge sources and their geography on innovation activity in small Knowledge Intensive Business Services (KIBS). It draws on results from a survey conducted in 2010 of 342 small and medium (SME) KIBS in the UK’s, North East and West Midlands. It is shown that innovation is supported by knowledge gained from frequent interaction with regional and UK customers as well as more frequent interaction with local business networks, including informal contacts as well as national licensing arrangements, regional and UK commercial networks and UK public and professional infrastructure. Innovation capability is also enhanced by internationalisation through both traded and untraded relationships. Various industry-specific business networks and regional government agencies also act as important sources of knowledge and networking in de-industrialised regions. No support is found for benefits arising from the clustering of firms in similar line of business or with regional universities or public sector organisations. Also, while we acknowledge positive effect of R&D on KIBS innovativeness we argue that its' effect is much less important compared to regional and extra regional knowledge source

DEVELOPMENT AND OPTIMIZATION OF CARVEDILOL FORMULATION USING EXPERIMENTAL DESIGN

The aim of this paper was to develop and optimize the carvedilol tablets formulation using the full factorial design. The content of binder (PVP K30), content of disintegrant (crospovidone) and main compression force were used as the independent variables. Tablets were prepared by wet granulation. The percentage of released carvedilol from prepared formulation after 10 minutes was defined as the response. It has been found that formulation with the low content of binding agents (4.8%), high content of disintegrant (4.5%) and compression force of 50 N has the best profile of drug. The optimal formulation was defined based on implementation of pharmaceuticaltechnological tests (testing strength, friability, disintegrating, contents of drug substance, drug release profiles). The stability of the optimal formulation with carvedilol was estimated using the aging tests

Magnetic field tunable terahertz quantum well infrared photodetector

A theoretical model and a design of a magnetic field tunable CdMnTe/CdMgTe terahertz quantum well infrared photodetector are presented. The energy levels and the corresponding wavefunctions were computed from the envelope function Schr¨odinger equation using the effective mass approximation and accounting for Landau quantization and the giant Zeeman effect induced by magnetic confinement. The electron dynamics were modeled within the self-consistent coupled rate equations approach, with all relevant electron-longitudinal optical phonon and electron-longitudinal acoustic phonon scattering included. A perpendicular magnetic field varying between 0 T and 5 T, at a temperature of 1.5 K, was found to enable a large shift of the detection energy, yielding a tuning range between 24.1 meV and 34.3 meV, equivalent to 51.4 μm to 36.1 μm wavelengths. For magnetic fields between 1 T and 5 T, when the electron population of the QWIP is spin-polarized, a reasonably low dark current of ≤1.4×10–² A/cm² and a large responsivity of 0.36−0.64 A/W are predicted

Optimization of Quercetin Extraction from Green Tea (Camellia sinensis) Using Central Composite Design, and the Pharmacological Activity of the Extract

The aim of this paper was to optimize an extraction procedure of quercetin from green tea using central composite design. Extraction time, ethanol concentration, and solid to liquid ratio were selected as the independent variables, while quercetin yield was defined as a response. The impact of factors and their interactions on the quercetin yield was studied based on the results of ANOVA test. The extraction time of 58.5 min, ethanol concentration of 94.7 % (v/v), and solid to liquid ratio of 1:19.4 (m/v) were found as the optimal conditions. The experimental confirmation of the proposed optimal conditions indicated that there was a good agreement between the experimental and predicted values. In addition to quercetin, the presence of 17 bioactive compounds was confirmed in the green tea extract using mass spectrometry method. Antioxidant, antimicrobial and antitumor activity of the optimal extract was determined using DPPH assay, disk diffusion method, and MTT assay, respectively

An <i>in vivo cis</i>-Regulatory Screen at the Type 2 Diabetes Associated <i>TCF7L2</i> Locus Identifies Multiple Tissue-Specific Enhancers

Genome-wide association studies (GWAS) have repeatedly shown an association between non-coding variants in the TCF7L2 locus and risk for type 2 diabetes (T2D), implicating a role for cis-regulatory variation within this locus in disease etiology. Supporting this hypothesis, we previously localized complex regulatory activity to the TCF7L2 T2D-associated interval using an in vivo bacterial artificial chromosome (BAC) enhancer-trapping reporter strategy. To follow-up on this broad initial survey of the TCF7L2 regulatory landscape, we performed a fine-mapping enhancer scan using in vivo mouse transgenic reporter assays. We functionally interrogated approximately 50% of the sequences within the T2D-associated interval, utilizing sequence conservation within this 92-kb interval to determine the regulatory potential of all evolutionary conserved sequences that exhibited conservation to the non-eutherian mammal opossum. Included in this study was a detailed functional interrogation of sequences spanning both protective and risk alleles of single nucleotide polymorphism (SNP) rs7903146, which has exhibited allele-specific enhancer function in pancreatic beta cells. Using these assays, we identified nine segments regulating various aspects of the TCF7L2 expression profile and that constitute nearly 70% of the sequences tested. These results highlight the regulatory complexity of this interval and support the notion that a TCF7L2 cis-regulatory disruption leads to T2D predisposition.</p

On the coherence/incoherence of electron transport in semiconductor heterostructure optoelectronic devices

This paper compares and contrasts different theoretical approaches based on incoherent electron scattering transport with experimental measurements of optoelectronic devices formed from semiconductor heterostructures. The Monte Carlo method which makes no a priori assumptions about the carrier distribution in momentum or phase space is compared with less computationally demanding energy-balance rate equation models which assume thermalised carrier distributions. It is shown that the two approaches produce qualitatively similar results for hole transport in p-type Si1-xGex/Si superlattices designed for terahertz emission. The good agreement of the predictions of rate equation calculations with experimental measurements of mid- and far-infrared quantum cascade lasers, quantum well infrared photodetectors and quantum dot infrared photodetectors substantiate the assumption of incoherent scattering dominating the transport in these quantum well based devices. However, the paper goes on to consider the possibility of coherent transport through the density matrix method and suggests an experiment that could allow coherent and incoherent transport to be distinguished from each other

Estrus Induction in Sexually Mature Gilts with Different Hormonal Treatments

The aim of this study was to determine the effectiveness of the synchronized estrus induction in sexually mature gilts, after treatment with different hormonal treatments, given in the unknown phase of a spontaneous estrus cycle. Sexually mature gilts were used, with at least one spontaneous estrous cycle. A total of 90 gilts were treated with single i/m injection of 1,000 IU eCG (Folligon®), 40 gilts were treated with two separate i/m injection of 1 ml PGF2α (Dinolytic®), at an interval of 11 days, and 40 gilts were treated orally (within diet) with 20 mg of synthetic progestagen preparation Altrenogest (Regumate®), during 18 days. Estrus was detected twice daily, in the 10h to 12h intervals, by direct contact with the teaser boar. The best induction of synchronized estrus (in 90% of gilts), which appeared within the first 7 days (mean 5.3 days) after treatment, was found in gilts treated with progestagen preparations. In the three repetitions of treatment with eCG, within the first 7 days (mean 4.2 days) after the treatment, estrus was detected in 65%, 40% or 33% of the treated gilts. After treatment with luteolytic preparation PGF2α (Dynolitic®), estrus was detected in 40% of gilts, on average 5.5 days after treatment. The obtained results clearly show that the successful induction of synchronized estrus in sexually mature gilts can be done only by the method for prolongation of the luteal phase of the spontaneous estrous cycles, using progestagen preparations