Operando Spectroscopy Observation of Mo Clusters-Ti3 C2 TX Catalyst/Support Interface's Dynamic Evolution in Hydrogen Evolution Reaction.

The interaction between catalyst and support plays an important role in electrocatalytic hydrogen evolution (HER), which may explain the improvement in performance by phase transition or structural remodeling. However, the intrinsic behavior of these catalysts (dynamic evolution of the interface under bias, structural/morphological transformation, stability) has not been clearly monitored, while the operando technology does well in capturing the dynamic changes in the reaction process in real time to determine the actual active site. In this paper, nitrogen-doped molybdenum atom-clusters on Ti3 C2 TX (MoACs /N-Ti3 C2 TX ) is used as a model catalyst to reveal the dynamic evolution of MoAcs on Ti3 C2 TX during the HER process. Operando X-ray absorption structure (XAS) theoretical calculation and in situ Raman spectroscopy showed that the Mo cluster structure evolves to a 6-coordinated monatomic Mo structure under working conditions, exposing more active sites and thus improving the catalytic performance. It shows excellent HER performance comparable to that of commercial Pt/C, including an overpotential of 60 mV at 10 mA cm-2 , a small Tafel slope (56 mV dec-1 ), and high activity and durability. This study provides a unique perspective for investigating the evolution of species, interfacial migration mechanisms, and sources of activity-enhancing compounds in the process of electroreduction.

Assessment of cerebral infarction after transient cerebral ischemic attack by ABCD2 score combined with the position of intracranial vascular stenosis.

This study aims to investigate the value of the ABCD score combined with the position of the offending vessel stenosis in predicting the risk of transient ischemic attack (TIA) to develop into cerebral infarction.The ABCD score and head magnetic resonance imaging + magnetic resonance angiography (MRA) results of 192 patients with TIA were retrospectively analyzed. With the 7th day as the endpoint time, these patients were divided into 3 groups, according to ABCD scores: low-risk group (n = 105), moderate-risk group (n = 60), and high-risk group (n = 27). Blood vessels were screened using head MRA results, and patients were accordingly divided into 2 groups: proximal vascular stenosis group (n = 71) and nonproximal vascular stenosis group (n = 171). Then, the association of the position of the intracranial vascular stenosis and ABCD score with short-term prognosis was analyzed.Based on the ABCD score, the incidence of cerebral infarction after 1 week was significantly higher in the high-risk group (85.7%) than in the moderate-risk group (16.7%) and low-risk group (1.9%), and the differences were statistically significant (P < .05). When the ABCD score was ≥4 points, the incidence of cerebral infarction after 1 week was significantly higher in the proximal vascular stenosis group (59.1%) than in the nonproximal vascular stenosis group (30.8%), and the difference was statistically significant (P < .05). When the ABCD score was <4 points, the incidence of cerebral infarction after 1 week in the proximal stenosis group (2%) was not significantly different from that in the nonproximal stenosis group (1.9%, P > .05).The ABCD score combined with proximal offending vessel stenosis can improve the short-term prediction of cerebral infarction in patients with TIA.

[Semi-analysis algorithm to retrieve pigment concentrations in the red tide area of the East China Sea].

For the purpose of detecting and forecasting research of red tides to reduce the loss, a semi-analytic algorithm to retrieve chlorophyll-a concentrations was established in the area where red tides often brought out, according to the data collected during the red tides cruise in the East China Sea in April 2002. In the algorithm, empirical equations were made based on the coefficients from the in-situ data, including the optical properties of the research area. The in-situ data were used to validate the algorithm. The discrepancy of chlorophyll-a absorption coefficients and concentrations are mainly located in the region of 30%. The root mean deviation of the chlorophyll-a concentrations between the observed and the calculated is 0.24, the maximum relative deviation 40.93%, the mean relative deviation 18.83% and the correlation coefficient 0.83. The results show that the precision of the algorithm is high and the algorithm is fit for the research area.