Biased Bowl-Direction of Monofluorosumanene in the Solid State.

A new curved π-conjugated molecule 1-fluorosumanene (1) was designed and synthesized that possesses one fluorine atom on the benzylic carbon of sumanene. This compound can exhibit bowl inversion in solution, leading to the formation of two diastereomers, 1endo and 1exo, with different dipole moments. Experimental and theoretical investigation revealed an energetical relationship among 1exo, 1endo, and solvent to realize the various endo:exo ratios in the single crystals of 1 depending on the crystallization solvent. Significantly, the molecular dynamics (MD) simulations revealed that 1exo positively worked for the elongation of the stacking structure and the final endo:exo ratio was affected by the relative stability difference between 1endo and 1exo derived by solvation. Such an arrangeable endo:exo ratio of 1 realized the preparation of unique materials showing a different dielectric response from the same molecule 1 just by changing the crystallization solvent.

Age-, season- and gender-specific reference intervals of serum 25-hydroxyvitamin D3 for healthy children (0 ~ 18 years old) in Nanning area of China.

Establishing specific reference intervals (RIs) of serum 25-hydroxyvitamin D3 [25(OH)D] for children is essential for improving the accuracy of diagnosis and prognosis monitoring of diseases such as rickets and growth retardation. The study including 6,627 healthy children was conducted to establish specific RIs of 25(OH)D for children in Nanning area of China. The results showed that there were statistically significant differences among age, season, and gender of serum 25(OH)D levels, and the age-specific RIs of serum 25(OH)D were 20.3 ~ 53.6 ng/mL for 0 ~ ≤ 1 year and 18.9 ~ 49.6 ng/mL for 2 ~ ≤ 3 years. The age-, season-specific RIs of serum 25(OH)D for 4 ~ ≤ 6 years in spring-summer and autumn-winter were 15.8 ~ 42.6 ng/mL and 15.2 ~ 37.7 ng/mL, respectively. The age-, gender-specific RIs of serum 25(OH)D for 7 ~ ≤ 18 years for males and females were 12.1 ~ 36.1 ng/mL and 10.8 ~ 35.3 ng/mL, respectively. This study successfully established the RIs of serum 25(OH)D, which may help to improve disease diagnosis and monitoring for children in the Nanning area of China.

Preparation and Thermal Performance of Fatty Acid Binary Eutectic Mixture/Expanded Graphite Composites as Form-Stable Phase Change Materials for Thermal Energy Storage.

A series of fatty acid binary eutectic mixture/expanded graphite (FABEM/EG) composite phase change materials (CPCMs) were prepared by absorbing a liquid FABEM into the EG. The thermal properties, thermostability, and thermoreliability were determined by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and thermal cycling tests, respectively. Fourier transform infrared spectrometry (FT-IR) and scanning electron microscopy (SEM) were used to analyze the chemical structure and microstructure, respectively. Thermal conductivity measurements and heat storage/release experiments were carried out to study the heat transfer performance. The DSC test results show that the phase transition temperatures and latent heat of these CPCMs are in the range of 17.8-55.2 °C and 134.9-176.2 J/g, respectively. FT-IR analysis indicates there is only a simple physical adsorption between EG and the PCM and no chemical reaction occurs. SEM results show that the fatty acid binary eutectic mixtures are well adsorbed in the pores of EG, and EG can provide a certain mechanical strength and prevent phase change materials from leaking. The thermal conductivity measurement and heat storage/release experiment show that the addition of EG greatly improves the thermal conductivities of the CPCMs. TGA test results and thermal cycle tests show that the CPCMs have excellent thermal stability and long-term cycling thermal reliability.

ESG Performance and Stock Price Volatility in Public Health Crisis: Evidence from COVID-19 Pandemic.

Unlike traditional financial crises, COVID-19 is a global public health crisis with a significant negative impact on the global economy. Meanwhile, the stock market has been hit hard, and corporate share prices have become more volatile. However, the stock prices of some enterprises with good performance of ESG (Environment, Social, and Governance) are relatively stable in the epidemic. This paper selects ESG rating data from MSCI (Morgan Stanley Capital International) with better differentiation, adopts multiple regression and dummy variables, and adopts the Differences-in-Differences (DID)model with the help of COVID-19, an exogenous event. Empirical test the impact of ESG performance on the company's stock price fluctuations. The results show that the stock price volatility of companies with good ESG performance is lower than that of companies with poor performance. Second, COVID-19 exacerbates volatility in company stock prices, but the increase in stock price volatility of companies with good ESG performance is small. That is, good ESG performance helps reduce the increase in stock price volatility due to COVID-19 shock, and plays a role in enhancing "resilience" and stabilizing stock prices. This paper provides new empirical evidence for the study of ESG performance and corporate stock price volatility, and puts forward relevant policy recommendations for enterprises and government departments.

Preparation and characterization of myristic acid/expanded graphite composite phase change materials for thermal energy storage.

Myristic acid/expanded graphite (MA/EG) composite phase-change material (CPCM) was prepared by absorbing liquid MA (as the PCM) into EG (as the supporting material). Its chemical structure, microstructure, and thermal properties were characterized and studied. In the MA/EG CPCM, the largest mass content of MA was 93.5% by using the diffusion-exudation circle method for the first time. Fourier transform infrared spectroscopy (FTIR) analysis indicated that the MA and EG were a pure physical mixture of which the structure does not change, and they undergo no chemical reaction. Differential-scanning-calorimetry (DSC) analysis results showed that the melting and freezing temperatures of the MA/EG CPCM were 53.3 and [Formula: see text], respectively, and the melting and freezing latent heats were 189.5 and 187.8 J/g, respectively. After several heat-cycle accelerations, the material still had good thermal-energy-storage effect. MA/EG CPCM thermoconductivity was greatly enhanced after adding EG, and the results of thermal-storage/-release experiments indicated that the thermal-storage and -release ratios of the MA/EG phase-change unit was greatly improved when compared with that of MA. These results indicated that the MA/EG CPCM was a suitable low-temperature thermal-energy-storage material.

Selective cytotoxicity of marine-derived fungal metabolite (3S,6S)-3,6-dibenzylpiperazine-2,5-dione against cancer cells adapted to nutrient starvation.

The cancer cells that are adapted to the hypoxic and nutrient-starved conditions of the tumor microenvironment have become a key target for anticancer therapies. In the course of search for selective cytotoxic substances against cancer cells adapted to nutrient starvation, (3S,6S)-3,6-dibenzylpiperazine-2,5-dione (1) was isolated from culture extract of marine-derived Paecilomyces formous 17D47-2. Compound 1 showed cytotoxic activity on the human pancreatic carcinoma PANC-1 cells adapted to glucose-starved conditions with IC50 value of 28 µM, whereas no effect was observed against PANC-1 cells under general culture conditions up to 1000 µM. Further studies on the mechanism of the selective cytotoxicity of 1 against the glucose-starved PANC-1 cells suggest that it may function via uncoupling of mitochondrial oxidative phosphorylation.

HCV and HIV infection among heroin addicts in methadone maintenance treatment (MMT) and not in MMT in Changsha and Wuhan, China.

OBJECTIVE: To compare HCV and HIV infection among heroin addicts in MMT and not in MMT in two large cities in central China. METHODS: A total of 541 heroin addicts were recruited from MMT clinics and voluntary detoxification centers in Changsha and Wuhan, China. Structured questionnaires collected data on their socio-demographics, clinical status, risk behaviors, and their knowledge of HIV. Their HIV serostatus and Hepatitis C virus (HCV) serostatus were determined by testing antibodies in blood serum. RESULTS: We observed a higher prevalence of HCV infection among MMT heroin addicts (82.3%) than that in the non-MMT group (50.6%). However, our findings indicated that the heroin addicts in MMT had less drug or sexual HIV/HCV risk behaviors and more knowledge about HIV than non-MMT addicts. The heroin addicts in MMT had a significantly higher percentage of individuals who always used condoms (44.9%) compared with patients in the non-MMT group (14.6%, p = 0.039), and they had more knowledge about HIV than non-MMT individuals (p<.001). The percentage of HIV-positive addicts in the MMT group (0.7%) and non-MMT group (0.8%) were almost same. CONCLUSION: Our study indicated that the rate of HCV infection among heroin addicts among MMT or non-MMT settings in central China is very high. The non-MMT heroin addicts have higher risk of becoming infected with HCV in the future, while at present they have lower rates of HCV infection than MMT heroin addicts. Although rates of HIV infection among MMT and non-MMT heroin addicts are low now, they are all at great risk of becoming infected with HIV in the future, especially for non-MMT heroin addicts. We should use the MMT sites as a platform to improve the control of HCV and HIV infection in heroin addicts.