The thickness-dependent band gap and defect features of ultrathin ZrO2 films studied by spectroscopic ellipsometry.

The band gap and defect features of ultrathin ZrO2 films with varying thicknesses have been investigated by spectroscopic ellipsometry through the point-by-point data inversion method. The ε2-sprectra in the 3-6 eV range are extracted based on an optical model consisting of a Si substrate/effective ZrO2 film/air ambient structure where the effective ZrO2 film is a combination of interfacial layers and ZrO2. Evident widening of the band gap with a reducing size is observed when the effective ZrO2 films are below a critical thickness, somewhere between 8.80 nm and 17.13 nm. This is due to quantum-confinement and amorphous effects. Moreover, the sub-band-gap defects at interfacial layers and in bulk ZrO2 are identified and present strong thickness dependence as well. The interfacial defects at 3.26, 4.13, 4.43, and 4.77 eV mainly exist below the critical thickness and exhibit a significant suppression with increasing film thickness. The bulk defects at 4.15 eV and 4.46 eV dominate in ZrO2 films once they are over the critical thickness. The evolution of the band gap and defects is closely related to variance in the electronic structure of amorphous ZrO2. Our results may be helpful in understanding controversial problems concerning the size effect on ultrathin high-k oxide films and exploring the further miniaturization of electronic devices based on them.

A Novel Group Decision-Making Method Based on Sensor Data and Fuzzy Information.

Algal bloom is a typical phenomenon of the eutrophication of rivers and lakes and makes the water dirty and smelly. It is a serious threat to water security and public health. Most scholars studying solutions for this pollution have studied the principles of remediation approaches, but few have studied the decision-making and selection of the approaches. Existing research uses simplex decision-making information which is highly subjective and uses little of the data from water quality sensors. To utilize these data and solve the rational decision-making problem, a novel group decision-making method is proposed using the sensor data with fuzzy evaluation information. Firstly, the optimal similarity aggregation model of group opinions is built based on the modified similarity measurement of Vague values. Secondly, the approaches' ability to improve the water quality indexes is expressed using Vague evaluation methods. Thirdly, the water quality sensor data are analyzed to match the features of the alternative approaches with grey relational degrees. This allows the best remediation approach to be selected to meet the current water status. Finally, the selection model is applied to the remediation of algal bloom in lakes. The results show this method's rationality and feasibility when using different data from different sources.

Dynamic Correlation Analysis Method of Air Pollutants in Spatio-Temporal Analysis.

Pollutant analysis and pollution source tracing are critical issues in air quality management, in which correlation analysis is important for pollutant relation modeling. A dynamic correlation analysis method was proposed to meet the real-time requirement in atmospheric management. Firstly, the spatio-temporal analysis framework was designed, in which the process of data monitoring, correlation calculation, and result presentation were defined. Secondly, the core correlation calculation method was improved with an adaptive data truncation and grey relational analysis. Thirdly, based on the general framework and correlation calculation, the whole algorithm was proposed for various analysis tasks in time and space, providing the data basis for ranking and decision on pollutant effects. Finally, experiments were conducted with the practical data monitored in an industrial park of Hebei Province, China. The different pollutants in multiple monitoring stations were analyzed crosswise. The dynamic features of the results were obtained to present the variational correlation degrees from the proposed and contrast methods. The results proved that the proposed dynamic correlation analysis could quickly acquire atmospheric pollution information. Moreover, it can help to deduce the influence relation of pollutants in multiple locations.

[Research on modeling and simulation of the system of position transformation mechanical ventilation].

The principle of Position Transformation Mechanical Ventilation (PTMV) was introduced briefly, and the mechanical structure and the intelligent control algorithm were studied. According to the principle and function requirement of PTMV, the mechanical structure of slip pole driven rocking chair(SPDRC) was proposed, the dynamics model of SPDRC was established, and the auto disturbance rejection controller was designed. The integrated model of control system was structured by using ADAMS and MATLAB, and the model validation and simulation were implemented. The simulation results indicate that the mechanical structure is feasible and the control process of ADRC is precise and steady.

Present status and expectation of aristaless-related homeobox (ARX) in endocrine pancreas.

The aristaless-related homeobox (ARX) gene has become one of most frequently mutated genes which is closely linked with development of the vertebrate central nervous system; however, the molecular and clinical bases of its function in the proliferation and differentiation of the endocrine pancreas have not, to date, been systematically characterized. ARX is considered as a regulator which determines endocrine cell fate and a bio-marker of the pancreatic α-cell. Disruption and mutation of ARX are found to lead to the deletion and reduction of α-cells both in mice models and in humans. Furthermore, expression of ARX is regulated by multiple transcription factors involved in development of the pancreas, such as Ngn3, Isl1, Nkx2.2 and Nkx6.1. Taken together, given the vital importance of glucagon in diabetes treatment, it is possible that ARX may down-regulate exorbitant glucagon levels by reducing the number of α-cells as a direct target; thus, the role of ARX in the maintenance of α-cell identity and quantity should be investigated and summarized. This article mainly focuses on the role of ARX in the endocrine pancreas, introduces the ARX-related animal model and transcription factors, and highlights the latest advances in our understanding in order to provide a clearer theoretical foundation for future scientific research.

[Determination of the activity of cytochrome P-450 CYP2A6 by HPLC method with caffeine as metabolizing probe].

AIM: To establish a HPLC method for determining five major metabolites of caffeine in the urine, 5-acetylamino-6-formylamino-3-methyluracil (AFMU), 1-methylxanthine (1X), 1-methyluric acid (1U), 1,7-dimethyluric acid (17U) and 1,7-dimethylxanthine (17X) and assess the activity of cytochrome P-450 CYP2A6. METHODS: The contents of five major metabolites of caffeine in the urine were determined by RP-HPLC method. Frequency distribution histogram was drawn by calculating the 17U/(AFMU + 1X + 1U + 17X + 17U) and then evaluated the activity of CYP2A6. RESULTS: The frequency distribution histograms of CYP2A6 approximately indicated three distinct groups, the cut of point is 0.23 between fast metabolizer and intermediate type. And the cut of point is 0.15 between slow metabolizer and intermediate type. CONCLUSION: The method is simple and rapid, suitable for the determination of metabolites of caffeine in urine. The method can be used to assay the activity of CYP2A6.

Alterations in the expression of Hs1-associated protein X-1 in the rat retina after optic nerve crush.

HS-1-associated protein X-1 (Hax-1) has been suggested to be expressed in various rodent and human tissues. Accumulating evidence has demonstrated that Hax­1 exerts an anti­apoptotic effect in neurological diseases. Furthermore, it has also been reported that Hax­1 interacts with various apoptosis­associated proteins, including high temperature-regulated A2 (HtrA2) and caspase­3. Previous studies have indicated that abnormal expression of Hax­1 may be associated with the development of the nervous system and with the pathophysiology of neurological diseases, including traumatic brain injury and cerebral ischemia. The present study reported temporal­spatial patterns of Hax­1 in rat retina following optic nerve crush (ONC). Using western blotting and double­immunofluorescence, significant upregulation of Hax­1 was observed in retinal ganglion cells (RGCs) in the retina following ONC. Increased Hax­1 expression was demonstrated to be accompanied by upregulation of active­caspase­3 and HtrA2 following ONC. In addition, Hax-1 co­localized with active caspase­3 and HtrA2 in RGCs following ONC. Terminal deoxynucleotidyl transferase­mediated biotinylated-dUTP nick­end labeling staining suggested that Hax­1 was involved in RGC apoptosis following ONC. Thus, these results suggested that Hax­1 may participate in regulating RGC apoptosis via interacting with caspase­3 and HtrA2 following ONC.

The impact of thickness and thermal annealing on refractive index for aluminum oxide thin films deposited by atomic layer deposition.

The aluminum oxide (Al2O3) thin films with various thicknesses under 50 nm were deposited by atomic layer deposition (ALD) on silicon substrate. The surface topography investigated by atomic force microscopy (AFM) revealed that the samples were smooth and crack-free. The ellipsometric spectra of Al2O3 thin films were measured and analyzed before and after annealing in nitrogen condition in the wavelength range from 250 to 1,000 nm, respectively. The refractive index of Al2O3 thin films was described by Cauchy model and the ellipsometric spectra data were fitted to a five-medium model consisting of Si substrate/SiO2 layer/Al2O3 layer/surface roughness/air ambient structure. It is found that the refractive index of Al2O3 thin films decrease with increasing film thickness and the changing trend revised after annealing. The phenomenon is believed to arise from the mechanical stress in ALD-Al2O3 thin films. A thickness transition is also found by transmission electron microscopy (TEM) and SE after 900°C annealing.

Optical properties of epitaxial BiFeO3 thin film grown on SrRuO3-buffered SrTiO3 substrate.

The BiFeO3 (BFO) thin film was deposited by pulsed-laser deposition on SrRuO3 (SRO)-buffered (111) SrTiO3 (STO) substrate. X-ray diffraction pattern reveals a well-grown epitaxial BFO thin film. Atomic force microscopy study indicates that the BFO film is rather dense with a smooth surface. The ellipsometric spectra of the STO substrate, the SRO buffer layer, and the BFO thin film were measured, respectively, in the photon energy range 1.55 to 5.40 eV. Following the dielectric functions of STO and SRO, the ones of BFO described by the Lorentz model are received by fitting the spectra data to a five-medium optical model consisting of a semi-infinite STO substrate/SRO layer/BFO film/surface roughness/air ambient structure. The thickness and the optical constants of the BFO film are obtained. Then a direct bandgap is calculated at 2.68 eV, which is believed to be influenced by near-bandgap transitions. Compared to BFO films on other substrates, the dependence of the bandgap for the BFO thin film on in-plane compressive strain from epitaxial structure is received. Moreover, the bandgap and the transition revealed by the Lorentz model also provide a ground for the assessment of the bandgap for BFO single crystals.