Studies of the Genotoxicity of Glycidyl Methacrylate (GMA)

The following experiments were conducted to evaluate the genotoxic effects of GMA (glycidyl methacrylale) on mammalian and human cells.(1) Using the absorption spectrum shift method in vitro, we observed that the maximums of calf thymus DNA and GMA were shifted toward longer wavelengths (a change of more than 15nm) and the absorbance decreased after incubation at room temperature for 15min or more.The result indicates that binding of DNA and GMA had occurred.The binding force is strong, not affected by the addition of concentrated sodium chloride solution, and only slightly decreased by the addition of 8 M urea solution.Therefore the bond between DNA and GMA might be covalent.(2) In cell cultures, unscheduled DNA synthesis (UDS) in human and/or rat lymphocyte was induced and DNA semiconserva-tive replication was inhibited by GMA at concentrations of less than 5.2 mM.(3) Sperm abnormality tests and assays of UDS in germ cells of male mice were conducted to study the in vivo genotoxicity of GMA.The results revealed that GMA could damage DNA, increase sperm abnormality frequency, and reduce the number of sperm cells, 1990 Academic Press.Inc.

The Association of Psychological Stress Related Cytokines (TNF Alpha, IFN-Gamma) with Essential Hypertension in Ningxia Hui Autonomous Region

The study aimed to explore the association between psychological stress-related cytokines and essential hypertension to provide the theoretical basis for the prevention and control of the essential hypertension. We screened hypertension patients in six communities in Wuzhong City of Ningxia, and chose the healthy people who had lived in the same community for full 5 years as a control group. Finally, we selected 210 pairs of cases and controls randomly, including 108 pairs of Hui and 102 pairs of Han (50% male;age 35 -74). The results showed that the serum TNF alpha levels of hypertension group were higher than the control group (ρ 0.01), and the serum IFN-gamma levels were lower than the control group both in Hui and Han (ρ 0.01). Further analysis showed that the serum TNF alpha level of the Hui hypertension group was higher than the Han hypertension group (ρ 0.01), while the serum IFN-gamma level was lower than Han hypertension group (ρ 0.01). In conclusion, TNF alpha and IFN-gamma were the important related cytokines between psychological stress and hypertension, and taking effective measures to control the level of serum TNF alpha. IFN-gamma may have the vital significance in alleviating or preventing the genesis and development of essential hypertension.

英语学习者程式语的使用及其与英文口语流利度的关联分析

该研究借助语料探讨了汉语母语的英语学习者英文口语中三种不同长度的程式化语言分布特点,进一步利用典型相关模型(CCA)分析了这些英语学习者英文程式化语言的使用和其英文口语流利度的相互关系。流利度指标采用了四个时间性参数,程式化语言使用指标采用了三种不同长度的程式化语言使用参数。该研究使用语料取自86名汉语母语英语学习者英文口语。研究结果表明这些汉语母语英语学习者的英文口语流利度和其英文程式化语言的使用存在强相关关系。

Insight into synergistic antioxidation mechanisms of butyl hydroxyanisole with common synthetic antioxidants

Butyl hydroxyanisole(BHA) is usually blended with other synthetic antioxidants to improve the antioxidative property due to synergistic antioxidation. However, the synergistic antioxidation mechanisms of BHA with synergists have not been revealed yet. Thus, the antioxidation of BHA with butylated hydroxytoluene(BHT), tert-butylhydroquinone(TBHQ), or propyl gallate(PG) was investigated in the 2,2-azobis(2-amidino-propane) dihydrochloride oxidizing system. The contents of BHA, BHT, TBHQ,PG, and transformation products were measured by high-performance liquid chromatography. Transformation products were identified with liquid chromatography-mass spectrometry and gas chromatography–mass spectrometry. Results showed that synergistic antioxidation occurred between BHA and BHT, TBHQ, or PG. The synergistic antioxidation effect of BHA and BHT was attributed to the regeneration of BHA by BHT. Transformation products of BHA and BHT(compounds 6 and 7, dimers of BHA and BHT) had little contribution due to the relatively low content(<0.6%). The synergistic antioxidation effect of BHA and TBHQ or BHA and PG was attributed to the protective mechanism of TBHQ or PG on BHA. No transformation products were detected of BHA and TBHQ. Transformation products of BHA and PG(compounds 9 and 10, dimers of BHA and PG) had limited contribution due to the relatively low percentage(<7%). Therefore, BHA and BHT performed competitive antioxidation,while BHA and TBHQ or PG performed protective antioxidation.

The Influence of Third-party E-Commerce Platform Price Limits on the Dual-Channel Strategy of Manufacturers

Powerful platform operators always set price limits for sellers on the platform. This paper establishes Stackelberg game models according to two pricing models when the manufacturer enters the third-party e-commerce platform and sells products online. The first is a seller-pricing model in which the manufacturer decides the online price. The second is a platform-pricing model in which the platform decides the online price. We obtain the equilibrium results for these two models and the condition that allows the manufacturer to adopt the dual-channel strategy by comparing the operation decisions and performance of supply-chain members in the two models. Results show that the dual-channel strategy of the manufacturer always decreases the profit of the traditional retailer. In comparison with the sellerpricing model, the platform-pricing model always erodes parts of the manufacturers profit obtained by the dual-channel strategy. The manufacturer will pass on the partial loss to the retailer using relative leadership in the platform-pricing model, which renders the profit of the retailer lower than that in the seller-pricing model. Also, price limits do not always bring the platform more profits;sometimes the platform is forced to set a low price.

Influences of CeO_(2)morphology on enhanced performance of electro-Fenton for wastewater treatment

As a kind of rare-earth oxide,CeO_(2)has been considered as a great potential material for its abundant oxygen vacancies and catalysis activity in wastewater treatment.In this study,three ceria samples with different morphological structure were prepared,and their effect on contaminates degradation in electro-Fenton(E-Fenton)system was investigated.It is found that the morphology of CeO_(2)has great influence on promoting the performance of E-Fenton process.The rod-like CeO_(2)(R-CeO_(2))induced EFenton system shows higher azo dye X3 B removal and mineralization rates than cubs(C-CeO_(2))and octahedrons(O-CeO_(2)),and the degradation kinetic rate constants are 0.28,0.169 and 0.181 min^(-1)respectively,already surpass that of the blank one(0.120 min^(-1)).The H_(2)O_(2)generation capacity of R-CeO_(2)induced E-Fenton system is also superior to the others,and the corresponding Faraday current efficiency even increases to 166.2%at 2.5 min.Characterizations by scanning-transmission electron microscopy(STEM),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),electron spin resonance(ESR),Raman spectroscopy were conducted to disclose the mystery behind this phenomenon.The results indicate that the difference of surface oxygen vacancy density in different shaped CeO_(2)acts as a magic driving force for the accelerated oxygen reduction,and then leads to the enhanced degradation efficiency of E-Fenton system.This work provides a new insight into the development and application of rare-earth elements based catalyst in E-Fenton technology.

Leaching kinetics and permeability of polyethyleneimine added ammonium sulfate on weathered crust elution-deposited rare earth ores

At present,in-situ leaching of weathered crust elution-deposited rare earth ores(WCE-DREOs) encounter with problems such as long leaching cycles,slow infiltration rate and low product purity.In order to solve the above problems,the conventional leaching agent ammonium sulfate((NH_(4))_(2)SO_(4)) was compounded with polymeric surfactant polyethyleneimine(PEI) to form a composite leaching agent.The effects of leaching temperature,PEI concentration.flow rate and pH on leaching kinetics and permeability of rare earths(RE) and aluminum(AI) in orebody were studied.It is found that with temperature increasing,the time required to reach leaching equilibrium for both RE and Al is shortened,the apparent activation energies of RE and AI are 14.79 and 13.45 kJ/mol,respectively,and the leaching processes are in accordance with the outer diffusion control,When the concentrations of(NH_(4))_(2)SO_(4) and PEI in the composite leaching agent are 2.0 wt% and 0.4 wt%;the time required to reach leaching equilibrium for RE and AI is about 50% shorter than that using(NH_(4))_(2)SO_(4) alone,and the leaching efficiencies of RE are slightly higher than that of Al.Properly increasing the temperature and flow rate of the composite leaching agent can improve the leaching efficiencies of RE and Al,but pH has neglected effects on the leaching efficiencies of RE.At PEI concentrations below 0,4 wt%, the addition of PEI promotes the leaching of RE and AI.In column leaching studies of the WCE-DREO,the addition of 0.4 wt% PEI to the traditional leaching agent(NH_(4))_(2)SO_(4) has no impact on the leaching efficiencies of RE.However,it can significantly increase the infiltration rate of WCE-DREO,shortening the leaching time per 10 mL effluent from about 30 min for(NH_(4))_(2)SO_(4) leaching system to 20 min for the composite leaching system.The leaching time is shortened by one-third,and the leaching cost is reduced,which can provide theoretical guidance for the development and commercial implementation of novel composite leaching agent for WCE-DREO.