Sophisticated construction of binary PdPb alloy nanocubes as robust electrocatalysts toward ethylene glycol and glycerol oxidation.

The design of nanocatalysts by controlling pore size and particle characteristics is crucial to enhance the selectivity and activity of the catalysts. Thus, we have successfully demonstrated the synthesis of binary PdPb alloy nanocubes (PdPb NCs) by controlling pore size and particle characteristics. In addition, the as-obtained binary PdPb NCs exhibited superior electrocatalytic activity of 4.06 A mg-1 and 16.8 mA cm-2 towards ethylene glycol oxidation reaction (EGOR) and 2.22 A mg-1 and 9.2 mA cm-2 towards glycerol oxidation reaction (GOR) when compared to the commercial Pd/C. These astonishing characteristics are attributed to the attractive nanocube structures as well as the large number of exposed active areas. Furthermore, the bifunctional effects originated from Pd and Pb interactions help to display high endurance with less activity decay after 500 cycles, showing a great potential in fuel cells applications

Modelling and optimisation on scroll expander for waste heat recovery organic Rankine cycle

Scroll expander has demonstrated high efficiency at low power range. In this paper, a generic model of a scroll expander has been developed. It can calculate the ideal expander parameters to give the optimal efficiency and prevent under- or over-expansion at any given operating conditions or fluids. The dynamic model was validated by predicting the ideal volumetric expansion ratio with ideal expansion ratio of 4.03 at 0.7 MPa pressure, and showed agreement with experimental data. The results suggested that the rate of scroll increase K in the geometric model has little effect on volumetric expansion ratio or ideal scroll length of the expander, but when expansion ratio is kept constant, lower K value results in lower leakage losses

Tirofiban for Stroke without Large or Medium-Sized Vessel Occlusion

The effects of the glycoprotein IIb/IIIa receptor inhibitor tirofiban in patients with acute ischemic stroke but who have no evidence of complete occlusion of large or medium-sized vessels have not been extensively studied. In a multicenter trial in China, we enrolled patients with ischemic stroke without occlusion of large or medium-sized vessels and with a National Institutes of Health Stroke Scale score of 5 or more and at least one moderately to severely weak limb. Eligible patients had any of four clinical presentations: ineligible for thrombolysis or thrombectomy and within 24 hours after the patient was last known to be well; progression of stroke symptoms 24 to 96 hours after onset; early neurologic deterioration after thrombolysis; or thrombolysis with no improvement at 4 to 24 hours. Patients were assigned to receive intravenous tirofiban (plus oral placebo) or oral aspirin (100 mg per day, plus intravenous placebo) for 2 days; all patients then received oral aspirin until day 90. The primary efficacy end point was an excellent outcome, defined as a score of 0 or 1 on the modified Rankin scale (range, 0 [no symptoms] to 6 [death]) at 90 days. Secondary end points included functional independence at 90 days and a quality-of-life score. The primary safety end points were death and symptomatic intracranial hemorrhage. A total of 606 patients were assigned to the tirofiban group and 571 to the aspirin group. Most patients had small infarctions that were presumed to be atherosclerotic. The percentage of patients with a score of 0 or 1 on the modified Rankin scale at 90 days was 29.1% with tirofiban and 22.2% with aspirin (adjusted risk ratio, 1.26; 95% confidence interval, 1.04 to 1.53, P = 0.02). Results for secondary end points were generally not consistent with the results of the primary analysis. Mortality was similar in the two groups. The incidence of symptomatic intracranial hemorrhage was 1.0% in the tirofiban group and 0% in the aspirin group. In this trial involving heterogeneous groups of patients with stroke of recent onset or progression of stroke symptoms and nonoccluded large and medium-sized cerebral vessels, intravenous tirofiban was associated with a greater likelihood of an excellent outcome than low-dose aspirin. Incidences of intracranial hemorrhages were low but slightly higher with tirofiban

Real-Time Recognition and Localization Based on Improved YOLOv5s for Robot’s Picking Clustered Fruits of Chilies

Chili recognition is one of the critical technologies for robots to pick chilies. The robots need locate the fruit. Furthermore, chilies are always planted intensively and their fruits are always clustered. It is a challenge to recognize and locate the chilies that are blocked by branches and leaves, or other chilies. However, little is known about the recognition algorithms considering this situation. Failure to solve this problem will mean that the robot cannot accurately locate and collect chilies, which may even damage the picking robot’s mechanical arm and end effector. Additionally, most of the existing ground target recognition algorithms are relatively complex, and there are many problems, such as numerous parameters and calculations. Many of the existing models have high requirements for hardware and poor portability. It is very difficult to perform these algorithms if the picking robots have limited computing and battery power. In view of these practical issues, we propose a target recognition-location scheme GNPD-YOLOv5s based on improved YOLOv5s in order to automatically identify the occluded and non-occluded chilies. Firstly, the lightweight optimization for Ghost module is introduced into our scheme. Secondly, pruning and distilling the model is designed to further reduce the number of parameters. Finally, the experimental data show that compared with the YOLOv5s model, the floating point operation number of the GNPD-YOLOv5s scheme is reduced by 40.9%, the model size is reduced by 46.6%, and the reasoning speed is accelerated from 29 ms/frame to 14 ms/frame. At the same time, the Mean Accuracy Precision (MAP) is reduced by 1.3%. Our model implements a lightweight network model and target recognition in the dense environment at a small cost. In our locating experiments, the maximum depth locating chili error is 1.84 mm, which meets the needs of a chili picking robot for chili recognition

CFD analysis of variable wall thickness scroll expander integrated into small scale ORC systems

The studies of constant wall thickness scroll expander have pointed out that geometries with large built-in volume ratios are necessary to achieve high performances in small-sized organic Rankine cycle (ORC) units. The variable wall thickness expander design offers the opportunity of increasing the geometric expansion ratio with the number of scroll turns remaining unchanged to avoid sealing and lubricating issues. In this paper, unsteady and three-dimensional computational fluid dynamics (CFD) simulations of scroll expander using variable wall thicknesses were therefore carried out to investigate the effects of the geometry on the internal flow behaviour. The scroll expander was integrated into an ORC unit fed by R123. The dynamic mesh technology of ANSYS Fluent was applied to generate the deforming mesh in the expander working chambers. The aerodynamic performance analysis yielded how over-expansion phenomena occurred at low pressure ratio while under-expansion phenomena were existing at high pressure ratio which are consistent with the thermodynamic theory of scroll expander. The higher pressure ratio was also contributing to higher temperature drops during the expansion process. Moreover, the occurrence of flank leakages through the radial clearances and its effects on the flow field were pointed out further proving the thermodynamic theory of scroll expander

Gut Microbiota Mediates Skin Ulceration Syndrome Outbreak by Readjusting Lipid Metabolism in <i>Apostichopus japonicus</i>

The intestinal tract is the most important location for symbiotes and pathogens, and the microbiota plays a crucial role in affecting the health of the gut and other host organs. Dysbacteriosis in the intestinal system has been proven to be significant in skin ulceration syndrome (SUS) in sea cucumbers. This study investigates whether the gut microbiota and lipid metabolites are relevant to the initiation and progression of SUS in a Vibrio-splendidus-infected sea cucumber model. The tight junction genes were downregulated and the inflammatory factor gene transcriptions were upregulated after V. splendidus infection in the intestinal tissue of the sea cucumber. V. splendidus infection modulated the gut microbiota by interacting with Psychromonas macrocephali, Propionigenium maris, Bacillus cereus, Lutibacter flavus, and Hoeflea halophila. Meanwhile, the metabolites of the long-chain fatty acids in the intestinal tissue, including triglycerides (TG), phosphatidylethanolamines (PE), and phosphatidylglycerols (PG), were altered after V. splendidus infection. V. splendidus engaged in positive interactions with PG and PE and negative interactions with specific TG. These results related to gut microbiota and metabolites can offer practical assistance in the identification of the inflammatory mechanisms related to SUS, and this study may serve as a reference for predicting the disease

The impact of political connections on the efficiency of China's renewable energy firms

This study investigates the impact of political connections on firm efficiency as well as its mechanisms in Chinese renewable energy firms. The empirical results reveal a direct negative association between political connections and firm efficiency and an indirect correlation through political resources. The results indicate that the higher the level of political connections, the stronger the relationship between political connections and firm efficiency. Our findings also indicate that the impact of political connections is different between state-owned and non-state-owned firms. For state-owned firms, political connections are negatively correlated with firm efficiency and government subsidies are not beneficial for state-owned firms in promoting productivity. As for non-state-owned firms, there is a ‘double-edged sword’ effect of political connections on firm efficiency. On the one hand, political connections are associated with lower firm efficiency, but on the other hand, political connections can alleviate the adverse effects of financing constraints on non-state-owned firms. •Political connections and firm efficiency are negatively correlated.•Firms can benefit from political connections by obtaining more political resources.•Political connections decrease the efficiency by over-exploiting political resources.•The impacts of political connections are different between state-owned and non state-owned firms

CFD analysis of the influence of variable wall thickness on the aerodynamic performance of small scale ORC scroll expanders

This research paper presents a CFD analysis of small scale ORC scroll expanders using variable and constant wall thicknesses by providing back-to-back aerodynamic performance comparisons. The evaluation of the three-dimensional and transient CFD results shows that the shorter scroll profile length of the variable wall thickness design (VWD) generated lower average radial and axial gas forces. In addition, higher pressure gradients in between individual working chambers contributed to a higher peak of the tangential gas moment despite higher transient gas force and tangential gas moment variations. Moreover, the pressure trace analysis reveals that the expansion process was finished at a crank angle of 816° in VWD, compared to 996° in the constant wall thickness design (CWD). The studies of the static pressure distributions along the surface of the fixed scroll of the two geometries indicate that static pressure drops through local radial clearances were higher in VWD. However, a higher number of static pressure drops occurred in CWD. The expansion process of CWD was driven by lower pressure gradients resulting in a complete dissipation of the large-scale vortices in the expansion chambers of CWD at the crank angle of 672°, in contrast to 600° in the expansion chambers of VWD