Practical, efficient synthesis of metal oxide nanocrystals with good crystallinity and high specific surface area by a modified polymer-network gel method is demonstrated, taking ZnO nanocrystals as ...an example. A novel stepwise heat treatment yields significant improvement in crystal quality. Such nanophase materials can effectively degrade common organic dyes under solar radiation and can perform very well in photo-assisted detection of NO
gas. Other typical metal oxide nanocrystals with good crystallinity and high specific surface area were also synthesized successfully under similar conditions. This work provides a general strategy for the synthesis of metal oxide nanocrystals, balancing the crystallinity and specific surface area.
The Chinese government plans to adopt a low or no subsidy policy mechanism on renewable energy power development in the future. To achieve a balance between reducing financial burden on the ...government and ensuring profitability of investors as well as to account for the regional differences in China, a novel regional wind power grid feed-in tariff benchmark price mechanism by Net Present Value (NPV) method and Real Option (RO) method is proposed in this paper. The results voice support on the appropriateness of gradually decreasing the wind feed-in tariff (FIT) benchmark price to as low as the coal-fired FIT. The proposed FIT price level is presented as a price range on the basis of a guaranteed Internal Rate of Return (IRR) falls in between 8% to 15% for wind power investors. The results indicate that the current FIT price should be readjusted and redistributed. Although the FIT price in Central and South China grids is recommended to be relatively high, the NPV of wind farm project value in six regional grids are at the same level.
•A regional-power-grid-based wind FIT price mechanism is proposed.•Carbon emission trading scheme is considered under two scenarios.•Enterprise’s managerial flexibility and uncertainty is counted in the NPV model.•The calculation considers IRR ranges from 8% to 15%.•Policy implications are constructive for government and investors.
Roughness is usually regarded as one of the most important factors to evaluate the quality of grinding process and ground surface. Many grinding parameters are affecting ground surface roughness with ...different extents, however, the most influential factors are wheel dressing and wear effects which were unfortunately not get seriously attention in the previous researches. On the other hand, as a most common indicator, roughness is only a statistical evaluation which is not enough to describe the topography characteristics of a surface, especially under higher demands on grinding process and functional ground surface quality. Thus in this work, a 2D and 3D ground surface topography models were established based on the microscopic interaction mechanism model between grains and workpiece in grinding contact zone. In this study, besides grinding parameters, the wheel dressing and wear effects were taken into consideration, including dressing depth, dressing lead, geometry of diamond dressing tool and wear effects of both wheel and diamond dressing tool. A dressing and wear profile line, Ldw, which will describe how the grains’ shapes are changed, was established and added into a former 2D ground surface roughness prediction model. In order to obtain a better visual effect, a 3D topography model was established which is based on the interaction situations in real grinding process. Both 2D and 3D models will predict ground surface roughness more precisely and stably than traditional models by comparing with a dressing lead single-factor experiment. Results also showed that the selection of dressing parameters and dressing tools can refer to the formed shape of Ldw by comparing with grinding depth, ae, and the dressing lead should be carefully chosen which will greatly influence ground surface topography the most.
•A new numerical method of ground surface roughness and 2D/3D topography considering dressing and wear effects was developed.•Most of the grinding and dressing parameters were considered; conclusions showed that dressing lead influents grinding process the most.•The method was validated by comparing with experiment; new method has more precise and stable prediction abilities.•The method developed and the calculation programs can be further used in dressing and grinding process design and optimization.
Neutron-gamma discrimination is a tough and significative in experimental neutrons measurements procedure, especially for low-energy neutrons signal discrimination. In this work, based on the Pulse ...Shape Discrimination (PSD) and Back-Propagation (BP) artificial neural networks, a neutron-gamma discrimination method is developed to broaden the lower limit of energy threshold with the hidden layer of 20 neurons. Compared with neutron-gamma discrimination method based on PSD only, the developed neutron-gamma discrimination method based on the PSD and BP-ANN can discriminate neutron and gamma-ray signals with low energy threshold, which can discriminate signals up to 99.93%. Moreover, this work can reduce the energy threshold from 350 keV to 70 keV, as well as the acquired data utilization increased from 60% to more than 99.9%, which overcome the hardware limitations and distinguish neutron and gamma-ray signals, effectively. The developed neutron-gamma discrimination method and the trained neural network can be directly used to other experimental neutrons measurements.
•Based on the Pulse Shape Discrimination (PSD) and Back-Propagation (BP) artificial neural networks, a neutron-gamma discrimination method is developed to broaden the lower limit of energy threshold from 350 keV to 70 keV, and the acquired data utilization increases from 60% to more than 99.9%.•Compared with neutron-gamma discrimination method based on PSD only, the developed neutron-gamma discrimination method based on the PSD and BP-ANN can discriminate neutrons and gamma rays with low energy threshold, which can discriminate signals up to 99.93%.•In experiment, the inverse-time-of-flight spectroscopy technology is introduced to verify reliability of the developed neutron-gamma discrimination method.•The experiment verify that the trained neural network can also be used to other experimental measurements for neutron-gamma discrimination with low energy threshold.
This paper presents a new method to fabricate isotropic magnetorheological (MR) elastomers under natural conditions. In the absence of a magnetic field, a variety of MR elastomer samples made of ...carbonyl iron particles, silicon rubber and silicone oil, were fabricated. Their dynamic viscoelastic properties were characterized by a measurement system developed by our group. Also, the microstructure of the samples was observed by a scanning electron microscope. The effects of iron particles and additives on the MR effect and the relationship between microstructure and mechanical properties were investigated. Furthermore, a simple self-assembled microstructure was proposed to explain the inherent magnetoviscoelasticity of MR elastomers prepared in the absence of a magnetic field. The analytical results of the model are in agreement with experimental data. The study is also expected to provide a good guide for designing and preparing new MR elastomers.
Preoperative staging is essential for the planning of treatment of cancer. This study was designed to evaluate the accuracy of computed tomography (CT) in predicting the local stage of tongue cancer ...by comparing it with the gold standard of histopathology. A total of 233 patients with newly-diagnosed tongue cancer was retrospectively reviewed, and the size of the tumour and the status of the cervical lymph node were compared between CT images and histopathological results. Patients with stage II cancer were followed up to assess the influence of inaccurate preoperative staging on prognosis. The accuracy of local staging by CT was 47.6% (111/233), with 59.7% (139/233) for tumour stage, and 70.4% (164/233) for nodal stage. The greatest dimension of the tumour on the CT image was about 2mm less than that measured by histopathology. The estimated volume of tumour was a quarter smaller. The accuracy of predicting malignant lymph nodes by CT was 68.9% (n=161). Among patients with stage II disease, simultaneous neck dissection was less likely in the understaged group than in the accurately staged one. The reoperation rate was a little higher but not significantly so. We conclude that the accuracy of CT in predicting local staging for tongue cancer was only moderate, because it underestimated the size of the tumour and needed to improve the criteria for detecting malignant lymph nodes. Understaging on CT images may influence the prognosis of patients with early stage tongue cancer.
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In the past decade, garlic has become one of the most popular complementary therapies for blood pressure (BP) control used by hypertensive patients. Numerous clinical studies have ...focused on the BP-lowering effect of garlic, but results have been inconsistent. Overall, there is a dearth of information available to guide the clinical community on the efficacy of garlic in hypertensive patients.
To systematically review the medical literature to investigate the current evidence of garlic for the treatment of hypertension.
PubMed, the Cochrane Library and EMBASE were searched for appropriate articles from their respective inceptions until August 2014. Randomized, placebo-controlled trials comparing garlic vs. a placebo in patients with hypertension were considered. Papers were independently reviewed by two reviewers and were analyzed using Cochrane software Revman 5.2.
A total of seven randomized, placebo-controlled trials were identified. Compared with the placebo, this meta-analysis revealed a significant lowering effect of garlic on both systolic BP (WMD: −6.71 mmHg; 95% CI: −12.44 to −0.99; P = 0.02) and diastolic BP (WMD: −4.79 mmHg; 95% CI: −6.60 to −2.99; P < 0.00001). No serious adverse events were reported in any of the trials.
The present review suggests that garlic is an effective and safe approach for hypertension. However, more rigorously designed randomized controlled trials focusing on primary endpoints with long-term follow-up are still warranted before garlic can be recommended to treat hypertensive patients.
The tensile behaviors of Cu50Zr50 metallic glass (MG) films with the same cooling history as a function of film thickness are systematically studied by molecular dynamics simulations. It clearly ...reveals that with decreasing film thickness, a transition from the localized deformation to the non-localized deformation indeed occurs in Cu50Zr50 MG films, which might be a general phenomenon for all MGs. The thickness-dependent deformation mode change observed here, is then reasonably explained by the Griffith crack-propagation criterion.
The size effect on atomic structure of a Cu
Zr
amorphous system, including zero-dimensional small-size amorphous particles (SSAPs) and two-dimensional small-size amorphous films (SSAFs) together with ...bulk sample was investigated by molecular dynamics simulations. We revealed that sample size strongly affects local atomic structure in both Cu
Zr
SSAPs and SSAFs, which are composed of core and shell (surface) components. Compared with core component, the shell component of SSAPs has lower average coordination number and average bond length, higher degree of ordering, and lower packing density due to the segregation of Cu atoms on the shell of Cu
Zr
SSAPs. These atomic structure differences in SSAPs with various sizes result in different glass transition temperatures, in which the glass transition temperature for the shell component is found to be 577 K, which is much lower than 910 K for the core component. We further extended the size effect on the structure and glasses transition temperature to Cu
Zr
SSAFs, and revealed that the T
decreases when SSAFs becomes thinner due to the following factors: different dynamic motion (mean square displacement), different density of core and surface and Cu segregation on the surface of SSAFs. The obtained results here are different from the results for the size effect on atomic structure of nanometer-sized crystalline metallic alloys.
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