Two-dimensional electron gas related emissions in ZnMgO/ZnO heterostructures

Radiative recombination of two-dimensional electron gas(2DEG), induced by polarization and validated by Hall effect measurements, is investigated in ZnMgO/ZnO heterostructures grown by metal-organic chemical vapor deposition. The Mg composition, the depth profile distribution of Mg, the residual strain in ZnMgO caplayer, and the thickness of caplayer all significantly influence the 2DEG-related transitions in ZnMgO/ZnO heterostructures. Below or above ZnO donor bound exciton, three additional broad emissions persisting up to 100 K are assigned to the spatially indirect transitions from 2DEG electrons to the photoexcited holes towards the ZnO flat-band region or remaining at the heterointerface.Research is supported by the State Key Program for Basic Research of China under Grant No. 2011CB302003 and National Natural Science Foundation of China (Nos. 61025020 and 60990312)

The prevalence of depressive symptoms among older patients with hypertension in rural China

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139900/1/gps4628.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139900/2/gps4628_am.pd

Protocol of an ongoing randomized controlled trial of care management for comorbid depression and hypertension: the Chinese Older Adult Collaborations in Health (COACH) study

Abstract Background Depression and hypertension are common, costly, and destructive conditions among the rapidly aging population of China. The two disorders commonly coexist and are poorly recognized and inadequately treated, especially in rural areas. Methods The Chinese Older Adult Collaborations in Health (COACH) Study is a cluster randomized controlled trial (RCT) designed to test the hypotheses that the COACH intervention, designed to manage comorbid depression and hypertension in older adult, rural Chinese primary care patients, will result in better treatment adherence and greater improvement in depressive symptoms and blood pressure control, and better quality of life, than enhanced Care-as-Usual (eCAU). Based on chronic disease management and collaborative care principles, the COACH model integrates the care provided by the older person’s primary care provider (PCP) with that delivered by an Aging Worker (AW) from the village’s Aging Association, supervised by a psychiatrist consultant. One hundred sixty villages, each of which is served by one PCP, will be randomly selected from two counties in Zhejiang Province and assigned to deliver eCAU or the COACH intervention. Approximately 2400 older adult residents from the selected villages who have both clinically significant depressive symptoms and a diagnosis of hypertension will be recruited into the study, randomized by the villages in which they live and receive primary care. After giving informed consent, they will undergo a baseline research evaluation; receive treatment for 12 months with the approach to which their village was assigned; and be re-evaluated at 3, 6, 9, and 12 months after entry. Depression and HTN control are the primary outcomes. Treatment received, health care utilization, and cost data will be obtained from the subjects’ electronic medical records (EMR) and used to assess adherence to care recommendations and, in a preliminary manner, to establish cost and cost effectiveness of the intervention. Discussion The COACH intervention is designed to serve as a model for primary care-based management of common mental disorders that occur in tandem with common chronic conditions of later life. It leverages existing resources in rural settings, integrates social interventions with the medical model, and is consistent with the cultural context of rural life. Trial registration ClinicalTrials.gov ID: NCT01938963 ; First posted: September 10, 2013.https://deepblue.lib.umich.edu/bitstream/2027.42/143862/1/12877_2018_Article_808.pd

Temperature-dependent exciton-related transition energies mediated by carrier concentrations in unintentionally Al-doped ZnO films

The authors reported on a carrier-concentration mediation of exciton-related radiative transition energies in Al-doped ZnO films utilizing temperature-dependent (TD) photoluminescence and TD Hall-effect characterizations. The transition energies of free and donor bound excitons consistently change with the measured TD carrier concentrations. Such a carrier-concentration mediation effect can be well described from the view of heavy-doping-induced free-carrier screening and band gap renormalization effects. This study gives an important development to the currently known optical properties of ZnO materials.This research is supported by the State Key Program for Basic Research of China under Grant No. 2011CB302003, National Natural Science Foundation of China (Nos. 61025020, 60990312, and 61274058), Basic Research Program of Jiangsu Province (BK2011437), and the Priority Academic Program Development of Jiangsu Higher Education Institutions

Thermal pretreatment of sapphire substrates prior to ZnO buffer layer growth

The properties of ZnO buffer layers grown via metal-organic chemical vapor deposition (MOCVD) on sapphire substrates after various thermal pretreatments are systematically investigated. High-temperature pretreatments lead to significant modifications of the sapphire surface, which result in enhanced growth nucleation and a consequent improvement of the surface morphology and quality of the ZnO layers. The evolution of the surface morphology as seen by atomic force microscopy indicates an obvious growth mode transition from three-dimensional to quasi-two-dimensional as the pretreatment temperature increases. A minimum surface roughness is obtained when the pretreatment temperature reaches 1150 °C, implying that a high-temperature pretreatment at 1150 °C or above may lead to a conversion of the surface polarity from O-face to Zn-face, similar to processes in GaN material growth via MOCVD. By analyzing the evolution of the film properties as a function of pretreatment temperature, the optimal condition has been determined to be at 1150 °C. This study indicates that a high-temperature pretreatment is crucial to grow high-quality ZnO on sapphire substrates by MOCVD.This research was supported by the State Key Program for Basic Research of China under Grant No. 2011CB302003, National Natural Science Foundation of China (Nos. 61025020, 60990312, and 61274058), Basic Research Program of Jiangsu Province (BK2011437), and the Priority Academic Program Development of Jiangsu Higher Education Institutions

OsHAC1;1 and OsHAC1;2 function as arsenate reductases and regulate arsenic accumulation

Rice is a major dietary source of the toxic metalloid arsenic (As). Reducing its accumulation in rice (Oryza sativa) grain is of critical importance to food safety. Rice roots take up arsenate and arsenite depending on the prevailing soil conditions. The first step of arsenate detoxification is its reduction to arsenite, but the enzyme(s) catalyzing this reaction in rice remains unknown. Here, we identify OsHAC1;1 and OsHAC1;2 as arsenate reductases in rice. OsHAC1;1 and OsHAC1;2 are able to complement an Escherichia coli mutant lacking the endogenous arsenate reductase and to reduce arsenate to arsenite. OsHAC1:1 and OsHAC1;2 are predominantly expressed in roots, with OsHAC1;1 being abundant in the epidermis, root hairs, and pericycle cells while OsHAC1;2 is abundant in the epidermis, outer layers of cortex, and endodermis cells. Expression of the two genes was induced by arsenate exposure. Knocking out OsHAC1;1 or OsHAC1;2 decreased the reduction of arsenate to arsenite in roots, reducing arsenite efflux to the external medium. Loss of arsenite efflux was also associated with increased As accumulation in shoots. Greater effects were observed in a double mutant of the two genes. In contrast, overexpression of either OsHAC1;1 or OsHAC1;2 increased arsenite efflux, reduced As accumulation, and enhanced arsenate tolerance. When grown under aerobic soil conditions, overexpression of either OsHAC1;1 or OsHAC1;2 also decreased As accumulation in rice grain, whereas grain As increased in the knockout mutants. We conclude that OsHAC1;1 and OsHAC1;2 are arsenate reductases that play an important role in restricting As accumulation in rice shoots and grain

Distinct enhancement of sub-bandgap photoresponse through intermediate band in high dose implanted ZnTe:O alloys

The demand for high efficiency intermediate band (IB) solar cells is driving efforts in producing high quality IB photovoltaic materials. Here, we demonstrate ZnTe:O highly mismatched alloys synthesized by high dose ion implantation and pulsed laser melting exhibiting optically active IB states and efficient sub-gap photoresponse, as well as investigate the effect of pulsed laser melting on the structural and optical recovery in detail. The structural evolution and vibrational dynamics indicates a significant structural recovery of ZnTe:O alloys by liquid phase epitaxy during pulsed laser melting process, but laser irradiation also aggravates the segregation of Te in ZnTe:O alloys. A distinct intermediate band located at 1.8 eV above valence band is optically activated as evidenced by photoluminescence, absorption and photoresponse characteristics. The carrier dynamics indicates that carriers in the IB electronic states have a relatively long lifetime, which is beneficial for the fast separation of carriers excited by photons with sub-gap energy and thus the improved overall conversion efficiency. The reproducible capability of implantation and laser annealing at selective area enable the realization of high efficient lateral junction solar cells, which can ensure extreme light trapping and efficient charge separationThis research was supported by National Natural Science Foundation of China (Nos 61274058, 61271077, 61504057, 61574075 and 61322403), the Natural Science Foundation of Jiangsu Province (Nos BK2011437 and BK20130013), the Six Talent Peaks Project in Jiangsu Province (2014XXRJ001), the Priority Academic Program Development of Jiangsu Higher Education Institutions, and the Australian Research Council

Wip1-dependent modulation of macrophage migration and phagocytosis

Macrophage accumulation within the vascular wall is a hallmark of atherosclerosis. Controlling macrophage conversion into foam cells remains a major challenge for treatment of atherosclerotic diseases. Here, we show that Wip1, a member of the PP2C family of Ser/Thr protein phosphatases, modulates macrophage migration and phagocytosis associated with atherosclerotic plaque formation. Wip1 deficiency increases migratory and phagocytic activities of the macrophage under stress conditions. Enhanced migration of Wip1-/- macrophages is mediated by Rac1-GTPase and PI3K/AKT signalling pathways. Elevated phagocytic ability of Wip1-/- macrophages is linked to CD36 plasma membrane recruitment that is regulated by AMPK activity. Our study identifies Wip1 as an intrinsic negative regulator of macrophage chemotaxis. We propose that Wip1-dependent control of macrophage function may provide avenues for preventing or eliminating plaque formation in atherosclerosis