Ultrafast and stable phase transition realized in MoTe2-based memristive devices.

Phase engineering of two-dimensional transition metal dichalcogenides has received increasing attention in recent years due to its atomically thin nature and polymorphism. Here, we first realize an electric-field-induced controllable phase transition between semiconducting 2H and metallic 1T' phases in MoTe2 memristive devices. The device performs stable bipolar resistive switching with a cycling endurance of over 105, an excellent retention characteristic of over 105 s at an elevated temperature of 85 °C and an ultrafast switching of ∼5 ns for SET and ∼10 ns for RESET. More importantly, the device works in different atmospheres including air, vacuum and oxygen, and even works with no degradation after being placed in air for one year, indicating excellent surrounding and time stability. In situ Raman analysis reveals that the stable resistive switching originates from a controllable phase transition between 2H and 1T' phases. Density functional theory calculations reveal that the Te vacancy facilitates the phase transition in MoTe2 through decreasing the barrier between 2H and 1T' phases, and serving as nucleation sites due to the elimination of repulsive forces. This electric-field-induced controllable phase transition in MoTe2 devices offers new opportunities for developing reliable and ultrafast phase transition devices based on atomically thin membranes.

[Distribution of Typical Pollutants from Rainwater Sewer Sediments in Suzhou City].

In this study, we separately collected rainwater sewer sediments from typical samples in Suzhou city, such as the urban commercial district, historical and cultural protection area, cultural and educational area, and living area, and analyzed the particle size distribution of the sediments and the characteristics of carbon, nitrogen, phosphorus content, and pollution load distribution under each graded particle size. The median particle size D50 of each sample point was 16.55-327.50 µm, and the particle size trend was as follows:commercial area > living area > historical and cultural protection area > cultural and educational area. D50 was related to the total organic carbon (TOC). The total nitrogen (TN), total phosphorus (TP), and ammonia nitrogen (NH4+-N) were significantly positively correlated, as were the pollutants. The spatial difference of ω(TOC), ω(TN), ω(TP), and ω(NH4+-N) in rainwater sewer sediments from different regions was as follows:commercial area > historical and cultural protection area > living area > cultural and educational area, in which ω(TOC) was 0.84%-6.76%, and ω(TN), ω(TP), and ω(NH4+-N) were 917.5-12707.1, 196.1-2524.8, and 9.3-156.8 mg·kg-1, respectively. TOC, TP, and NH4+-N pollution loads were mainly concentrated on particles ≤ 75 µm and 250-1000 µm. Street dust pollutants highly differed spatially, with a high content of attached pollutants on street dust particles with a particle size of ≤ 75 µm. Various pollutants migrated into the street dust-pipes, and TP and TN showed certain enrichment characteristics in the sewer. Controlling the transportation of street dust and the accumulation of sediments in the sewer can reduce the pollution of sediment into the rivers during the rainy season.

[Effect of tianma gouteng decoction on the endothelial function and the renal protein expression in spontaneously hypertensive rats].

OJECTIVE: To observe the effect of tianma gouteng decoction (TGD) on the endothelial function and the renal protein expression of spontaneously hypertensive rats, and to analyze its possible mechanism. METHODS: Totally 18 6-week-old SHR were randomly divided into 3 groups according to randomized block design, the SHR control group, the TGD group, and the captopril group, 6 in each group. Meanwhile, Wistar Kyoto (WKY) rats of the same age were recruited as a WKY control group. Rats in the TGD group were administered with TGD at the daily dose of 10. 260 g/kg. Rats in the captopril group were administered with captopril at the daily dose of 3. 375 g/kg. 2 mL/100 g distilled water was administered to rats in the SHR control group and the WKY control group. All medication was performed by gastrogavage once per day till rats were 24 weeks old. Changes of blood pressure were measured once per two weeks. The relaxation of the thoracic aorta and the superior mesenteric artery was determined by vascular ring in vitro to reflect the endothelial function. The total renal protein was separated by two-dimensional electrophoresis (2-DE). The significantly deviated protein was verified by Western blot. RESULTS: (1) Compared with the SHR control group, blood pressure was significantly lowered in rats (10 - 24 weeks old) of the captopril group (P <0.01, P <0.05). The hypotensive effect of TGD was obvious at the beginning of hypertension (10 -12 weeks) (P <0. 01). But along with the progression of hypertension, its hypotensive effect was not obvious (P>0. 05). (2) Compared with the SHR control group, the relaxation of the superior mesenteric artery was obviously improved in the TGD group (P <0. 05); the relaxation of the thoracic aorta and the superior mesenteric artery was obviously superior in the WKY control group (P <0. 01, P <0. 05). But there was no statistical difference in each relaxation index between the captopril group and the SHR control group (P >0. 05).(3) RESULTS: of 2-DE found 16 significantly differential renal protein, mainly involved nitric oxide (NO) system, oxidative stress, and cytoskeleton-related proteins. Results of Western blot showed that TGD could significantly improve expressions of Cu-Zn superoxide dismutase (SOD), N(G, N(G)-dimethylarginine dimethylaminohydrolase 2 (DDAH2), and pterin-4-alpha-carbinolamine dehydratase 1 (PCBD1) (P <0. 05). CONCLUSION: GTD could protect the endothelial function of the superior mesenteric artery in SHR, and its intervention mechanism of hypertension induced early renal injury might be relevant to regulating the NO system and antioxidative stress.

[Analysis of renal protein expressions of spontaneously hypertensive rat intervention by three different Chinese medicine compounds for hypertension].

OBJECTIVE: To observe the differential protein expression profile of three different Chinese medicine compounds on spontaneous hypertensive rat, which were Banxiabaizhutianma Decoction, Dihuangyinzi Decoction and Tianmagouteng Decoction, and to elaborate their function characters and regulation pathway using the principal component analysis and analyze the basic theory of different treatment of hypertension. METHODS: Give three compounds to 6-week-old SHR (Spontaneous hypertensive rat) as experimental group and captopril to 6-week-old WKY (Wistar-Kyoto rat) as control group by gavage. Monitor the blood pressure of rat tail to 24-week-old and then all rats were decapitated. Extracte the rental protein to finish two-dimensional electrophoresis experiments and get the differential protein spots using PDQuest software. Study the three different compounds' effect of trend on SHR blood pressure using PCAC principal component analysis. RESULTS: The blood pressure of SHR remained rising from 6-week-old to 10-week-old, when Tianmagouteng Decoction had a significant anti-hypertension effect. But as the blood pressure of SHR remained high, Banxiabaizhutianma Decoction and Dihuangyinzi Decoction performed better in lowering blood pressure. At last, renal protein expression profile analysis showed that there were 84 significantly different proteins between SHR and WKY of 24-week-old and the PCA result showed that the principal component extraction was 95.951%, it was sure that Tianmagouteng Decoction and Banxiabaizhutianma Decoction had significantly changed rental protein spots on SHR while Dihuangyinzi Decoction had not. CONCLUSION: In the early stages of rising blood pressure, Tianmagouteng Decoction has significant anti-hypertensive effect. But when the blood pressure remain high, Banxiabaizhutianma Decoction and Dihuangyinzi Decoction are superior to Tanmagouteng Decoction in anti-hypertension. Banxiabaizhutianma Decoction and Tianmagouteng Decoction can significantly improve rental protein spots on SHR while Dihuangyinzi Decoction can not.