Fast Photoresponse and Long Lifetime UV Photodetectors and Field Emitters Based on ZnO/Ultrananocrystalline Diamond Films.

We have designed photodetectors and UV field emitters based on a combination of ZnO nanowires/nanorods (ZNRs) and bilayer diamond films in a metal-semiconductor-metal (MSM) structure. The ZNRs were fabricated on different diamond films and systematic investigations showed an ultra-high photoconductive response from ZNRs prepared on ultrananocrystalline diamond (UNCD) operating at a lower voltage of 2 V. We found that the ZNRs/UNCD photodetector (PD) has improved field emission properties and a reduced turn-on field of 2.9 V µm(-1) with the highest electron field emission (EFE) by simply illuminating the sample with ultraviolet (UV) light. The photoresponse (Iphoto /Idark ) behavior of the ZNRs/UNCD PD exhibits a much higher photoresponse (912) than bare ZNRs (229), ZNRs/nanocrystalline diamond (NCD; 518), and ZNRs/microcrystalline diamond (MCD; 325) under illumination at λ=365 nm. A photodetector with UNCD films offers superior stability and a longer lifetime compared with carbon materials and bare ZNRs. The lifetime stability of the ZNRs/UNCD-based device is about 410 min, which is markedly superior to devices that use bare ZNRs (92 min). The ZNRs/UNCD PD possesses excellent photoresponse properties with improved lifetime and stability; in addition, ZNRs/UNCD-based UV emitters have great potential for applications such as cathodes in flat-panel displays and microplasma display devices.

The effect of tetrafluoromethane plasma post-treatment on the electrical property of tungsten oxide nanowires.

The effects of tetrafluoromethane (CF4) plasma on the surface morphology, chemical compositions, and electrical property of tungsten oxide (W18O49) nanowires are investigated. The nanostructured tungsten oxide nanowires with average length of 250-350 nm were self-catalytically grown on Si substrate. By post-treatment with CF4 plasma for 10 min, the W18O49 nanowires on the substrate showed the highest current response. Longer CF4 plasma post-treatment time demonstrated higher etching effect which demolished the nanowires and resulted in lower conductivity of the samples. The disintegration of the W18O49 nanowires layer after CF4 plasma treatment, revealed physically by the decrease of the average thickness and chemically by the decrease of XRD peak ratio (I 23.0/I 26.0), was closely related to the overall electrical performance. The etching effect was further reveled by Raman spectra showing the evolution of O-W-O and W=O characteristics with the increased post-treatment time. Moreover, the improvement of the electrical property of W18O49 nanowires was elucidated by the exposure rate to explain the mechanism of plasma post treatment in three stages: passivation, degradation and ablation. The maximum exposure rate, corresponding to the maximum conductivity, was achieved by 10 min of CF4 plasma treatment. The time-differentiated exposure analyses confirmed the evolution of resistance of W18O49 nanowires on Si with different post-treatment time which supported the results of surface characterizations.

A novel blood-cell-two-compartment model for transferring a whole blood time activity curve to plasma in rodents.

The term input function usually refers to the tracer plasma time activity curve (pTAC), which is necessary for quantitative positron emission tomography (PET) studies. The purpose of this study was to acquire the pTAC by independent component analysis (ICA) estimation from the whole blood time activity curve (wTAC) using a novel method, namely the FDG blood-cell-two-compartment model (BCM). This approach was compared to a number of published models, including linear haematocrit (HCT) correction, non-linear HCT correction and two-exponential correction. The results of this study show that the normalized root mean square error (NRMSE) and the error of the area under curve (EAUC) for the BCM estimate of the pTAC were the smallest. Compartmental and graphic analyses were used to estimate the metabolic rate of the FDG (MR(FDG)). The percentage error for the MR(FDG) (PE(MRFDG)) was estimated from the BCM corrected pTAC and this was also the smallest. It is concluded that the BCM is a better choice when transferring wTAC into pTAC for quantification.

Interleukin-1alpha and -1beta promoter polymorphisms in Taiwanese patients with dementia.

BACKGROUND: Inflammatory events may contribute to the pathogenesis of dementia and interleukin-1 (IL-1) may exert both neurotoxic and neuroprotective effects. We investigated whether IL-1alpha -889 C/T and IL-1beta -511 C/T promoter polymorphisms are associated with the risk of Alzheimer's disease (AD) and vascular dementia (VaD). METHODS: AD patients (n = 219) and VaD patients (n = 82), who fulfilled the criteria of the NINCDS-ADRDA and NINDS-AIREN, and ethnic-matched and nondemented controls (n = 209) were analyzed by means of genotype association method. RESULTS: No significant difference in the genotype distribution of the analyzed single nucleotide polymorphisms was found between AD or VaD cases and controls. However, the frequency of the IL-1alpha -889 CT genotype was notably lower in VaD patients aged over 70 years than the age-matched controls (9.1 vs. 22.9%, p = 0.036) andtheIL-1alpha -889 CT genotype demonstrated a trend toward decrease in risk of developing VaD (odds ratio: 0.34; 95% confidence interval: 0.12-0.83, p = 0.026). Multivariate analysis revealed that the IL-1beta -511T-carrying genotype slightly strengthens the negative association of the IL-1alpha -889 CT genotype with VaD (odds ratio: 0.26; 95% confidence interval: 0.08-0.79, p = 0.024). CONCLUSION: Our data suggest a protective role of the IL-1alpha -889 CT genotype in VaD susceptibility among Taiwanese aged over 70 years.

Risk factors for vascular dementia: a hospital-based study in Taiwan.

BACKGROUND: In Taiwan, next to Alsheimer's, vascular dementia (VD) is the second leading cause of dementia in the elderly. Few studies have examined cardiovascular risk factors and their association with VD in Taiwan. METHODS: This is a case-control study using a sampling of subjects from the outpatient memory clinics of two hospitals. Identified cases were those patients diagnosed with VD based on the DSM-IV criteria. The controls were subjects with Clinical Dementia Rating Scale as 0, i.e. no dementia from the same dementia registry database. Exposure was recorded by means of a risk factor questionnaire or medical examination. RESULTS: There were a total of 190 patients with VD and 155 controls in this study. Significant risk factors were age, hypertension, diabetes and hyperlipidemia. There was no correlation with sex, education, cigarette smoking or alcohol consumption. CONCLUSIONS: This study confirmed reported cardiovascular risk factors contributing to VD as in Western countries.

[High temperature stress on rice anthesis: research progress and prospects].

High temperature-induced rice sterility at anthesis is characterized by its organ-specific, high severity, and low predictability of occurrence. This paper summarized the research advances in rice sterility at anthesis under high temperature, including occurrence period, injury temperature regime, differences in responses among varieties, damage mechanisms, evaluation methods, genetics of tolerance traits, and molecular biology of anther dehiscence and pollen abortion, etc. Based on the relevant researches in Japan as well as the studies in Jianghan Plain, China on the climate conditions under which high temperature-induced damage on middle-season rice hybrids occurred, some key points and main options for the further research were suggested.

Distributed collaborative CAD system based on Web Service.

This paper presents a novel Web Service based distributed collaborative CAD system employing feature as its collaborative design element and uses XML to define feature operations and communication protocol between the server and the client. To reduce network load and increase response ability of the system, the feature information is updated incrementally on the client. The system supports collaborative designing on heterogeneous platforms. Its framework and communication protocols are analyzed in detail. The experimental results from the developed prototype system showed that it can effectively support collaborative design under the distributed environment.

Intersections of two offset parametric surfaces based on topology analysis.

Conventional methods for solving intersections between two offset parametric surfaces often include iteratively using computationally expensive SSI (surface/surface intersections) algorithm. In addition, these methods ignore the relations between the intersection curves of parametric surfaces with different offset distances. The algorithm presented in this paper, makes full use of the topological relations between different intersection loops and calculates intersection loops with the help of previously calculated intersection loops. It first pre-processes two parametric surfaces to obtain the characteristic points, called topology transition points (TTPs), which can help in the subsequent finding of the topologies of the intersection curves. Then these points are categorized into several distinct groups, and we can determine the calculation strategy for searching initial points by analyzing the properties of these TTPs on the surfaces. Hence, all intersection curves can be marched from initial points by the tracing algorithm. The proposed algorithm could calculate intersection curves robustly and effectively, and has been tested to be capable of overcoming the degenerate conditions such as loop and singularities leaking that occur frequently in conventional algorithms.