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Developmental adversities early in life are associated with later psychopathology. Clustering may be a useful approach to group multiple diverse risks together and study their relation with psychopathology. To generate risk clusters of children, adolescents, and young adults, based on adverse environmental exposure and developmental characteristics, and to examine the association of risk clusters with manifest psychopathology. Participants (n = 8300) between 6 and 23 years were recruited from seven sites in India. We administered questionnaires to elicit history of previous exposure to adverse childhood environments, family history of psychiatric disorders in first-degree relatives, and a range of antenatal and postnatal adversities. We used these variables to generate risk clusters. Mini-International Neuropsychiatric Interview-5 was administered to evaluate manifest psychopathology. Two-step cluster analysis revealed two clusters designated as high-risk cluster (HRC) and low-risk cluster (LRC), comprising 4197 (50.5%) and 4103 (49.5%) participants, respectively. HRC had higher frequencies of family history of mental illness, antenatal and neonatal risk factors, developmental delays, history of migration, and exposure to adverse childhood experiences than LRC. There were significantly higher risks of any psychiatric disorder [Relative Risk (RR) = 2.0, 95% CI 1.8–2.3], externalizing (RR = 4.8, 95% CI 3.6–6.4) and internalizing disorders (RR = 2.6, 95% CI 2.2–2.9), and suicidality (2.3, 95% CI 1.8–2.8) in HRC. Social-environmental and developmental factors could classify Indian children, adolescents and young adults into homogeneous clusters at high or low risk of psychopathology. These biopsychosocial determinants of mental health may have practice, policy and research implications for people in low- and middle-income countries.
Hybrid organic-inorganic semiconducting interfaces have attracted attention in photodiodes and field-effect transistors (FETs) due to the realization of intrinsic p-n junctions and their mechanical flexibility. With the difficulty of developing high-mobility n-type organic semiconductors due to the necessity of low LUMO levels and ambient environment stability, solution processable inorganic materials are an excellent alternative. ZnO is an intrinsic n-type semiconductor which is non-toxic and sol-gel processable, creating avenues for film patterning and fully solution processed devices. We report the improvement of electron mobilities in ZnO FETs through simple UV-Ozone processing which reduces lattice defects within the film and at the SiO2/ZnO interface. Treated ZnO films yield electron mobilities close to 10-2 cm2/Vs and on/off current ratios of 104 while non-treated films have mobilities on the order of 10-5 cm2/Vs and an order of magnitude lower on/off current ratios. Treated films also yield improved photoresponsivity and detectivity in hybrid ZnO-organic photodetectors.
The present study details facile synthesis of hollow Cu2O nanospheres decorated with Ag nanoparticles using a simple surfactant technique for enhanced photocatalytic activity. The morphology and structure is studied via XRD and SEM. Cu2O hollow nanospheres with a diameter of 500-800 nm were synthesized via Ostwald ripening using CuSO4 aqueous solution. The catalytic activity of Cu2O is studied in the presence of UV and visible light using Methyl Orange (MO) as a model pollutant. Ag decorated Cu2O particles showed a 49% increase in photocatalytic activity over the undecorated Cu2O. The improved photocatalytic activity is achieved by surface plasmon resonance effects in the silver nanoparticles, allowing utilization of the lower energy portion of the solar spectrum.
In this paper, we report new phase of crystalline silicon, quasicrystalline silicon thin-film on glass substrate. The surface topography of these films reveal simultaneous existence of sixfold and fivefold symmetry. We found an array of quasi-unit cell in 2-D that formed quasicrystalline solid. This is first time demonstration of quasicrystalline for single element, silicon (Si). Raman spectra suggests that we found crystalline silicon structure on glass substrate that is not single-crystal silicon (c-Si) but very close to c-Si.
Temperature-dependent Hall-effect measurements have been performed on three Ga-doped ZnO thin films of various thicknesses (65, 177, and 283 nm), grown by pulsed laser deposition at 400 °C and annealed at 400 °C for 10 min in Ar, N2, or forming-gas (5% H2 in Ar). The donor ND and acceptor NAconcentrations as a function of sample thickness and annealing conditions are determined by a new formalism that involves only ionized-impurity and boundary scattering. Before annealing, the samples are highly compensated, with ND = (2.8 ± 0.3) × 1020 cm-3 and NA = (2.6 ± 0.2) × 1020 cm-3. After annealing in Ar the samples are less compensated, with ND = (3.7 ± 0.1) × 1020 cm-3 and NA = (2.0 ± 0.1) × 1020 cm-3; furthermore, these quantities are nearly independent of thickness. However, after annealing in N2 and forming-gas, ND and NA are thickness dependent, partly due to depth-dependent diffusion of N2 and H, respectively.
An attempt is made to understand the growth kinetics of carbon nanospheres (CNS) synthesized using a “green” technique. An aqueous solution of glucose, the precursor, was hydrothermally treated to produce porous CNS with homogeneous size distribution and smooth surfaces. The growth of CNS was studied by evaluating transmission electron microscope images as a function of hydrothermal reaction time and temperatures. Raman spectra revealed the presence of short-ordered graphitic nanostructures in an amorphous carbon matrix. FTIR spectroscopy confirms the carbonization of glucose and shows the presence of surface hydroxyl groups on CNSs. Based on various experimental observations it is proposed that the growth of CNSs is dictated by a reaction-controlled mechanism where long chain glucose-based oligomers bond to the CNS surface. The narrow size distribution and highly hydrophilic surface of these amorphous CNS makes them potential candidates for biomedical applications.
In this work, we report on nucleation and growth of silicon thin films on glass substrate with “five-fold” symmetry and “six-fold” symmetry by ceramics hot wire chemical vapor deposition. We observed “confinement of heat and photon” is a powerful approach in developing silicon thin films with novel structure, i.e. quasicrystalline silicon thin films on glass substrate. We found unambiguously that photons emitted from the hot filament influence the nucleation of nanocrystal silicon that produces new type of silicon thin films with “five-fold” symmetry and “six-fold” symmetry.
In this paper we report non magnetic elements (Al and Cu) doping effect on the structural and magneto-transport properties of Zn0.85Mn0.15O dilute magnetic semiconductors. Thin films of undoped Zn0.85Mn0.15O (ZnMnO), Al doped Zn0.80Al0.05Mn0.15O (ZnMnAlO), and Cu doped Zn0.85Cu0.05Mn0.15O (ZnMnCuO) were grown on sapphire single crystals using pulse laser deposition technique. X-Ray Diffraction and Raman Spectra confirm the epitaxial growth with a strong orientation along the c-axis. Scanning Electron Microscopy and Atomic Force Microscopy reveals surface microstructure of all the films. Magneto transport properties quantify the carrier concentrations and mobilities at room temperature in all the films.
In this paper, the effect of substrate on the domain structure growth and electrical and magnetic properties of epitaxial Mn-doped Zn0.8Mn0.15O (ZnMnO) thin films has been investigated. Epitaxial thin films of ZnMnO dilute magnetic semiconductors (DMS) were grown on various substrates such as single crystal sapphire, single crystal silicon, and quartz substrates using Pulsed Laser Deposition (PLD) technique . Structural, surface, magnetic, and optical properties have been observed on these films using X-Ray diffraction (XRD), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), and Raman spectroscopy. X-Ray Diffraction shows that films are highly epitaxial and c-axis oriented with some induced strain. AFM images show that film surface is smooth with RMS roughness of the order of 1-2 nm over 5*5sq.micron. Magnetic characteristic properties such as carrier concentration, mobility, and temperature dependent resistivity were also investigated. Carrier concentration decreases and mobility increases for both the films on silicon and quartz substrates when compared to film on sapphire.
The conductivity and magnetotransport properties of compression molded half-metallic CrO2/Polyimide composites over a range of different metallic concentrations have been studied. The conductivity measurements on these composites show negative slope of resistance versus temperature. The magnetoresistance measurement indicates obvious enhancement at low temperatures. The maximum in magnetoresistance (MR) is found to be temperature and metal volume fraction dependent. Significant differences in high and low temperature magnetoresistive behavior in the composite have been observed. The high field, 15 T MR measurements show 23% and 19% MR enhancement at 5K and 75 K, respectively. Thus, it is found that the polymer barrier can contribute to enhancing magnetoresistive properties of the composite.
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