白云石产品深加工技术研究——白云石小二甲(30mm～45mm)焙烧试验

本文通过对重钢矿业公司景星矿白云石小二甲焙烧试验项目进行叙述,提出了竖窑焙烧小粒级矿石的加工工艺和技术方案,有利于优化产品结构,提高白云石矿产资源的综合利用水平。

Protective effects of 2,4-dihydroxybenzophenone against acetaminophen-induced hepatotoxicity in mice

AIM:To examine the effects of 2,4-dihydroxybenzophenone(BP-1),a benzophenone derivative used as an ultraviolet light absorbent,on acetaminophen(APAP)induced hepatotoxicity in C57BL/6J mice.METHODS:Mice were administered orally with BP-1 at doses of 200,400 and 800 mg/kg body weight respectively every morning for 4 d before a hepatotoxic dose of APAP(350 mg/kg body weight) was given subcutaneously.Twenty four hours after APAP intoxication,the serum enzyme including serum alaine aminotransferase(ALT),aspartate aminotransferase(AST),lactate dehydrogenase(LDH) were measured and liver histopathologic changes were examined.RESULTS:BP-1 administration dramatically reduced serum ALT,AST and LDH levels.Liver histopathological examination showed that BP-1 administration antagonized APAP-induced liver pathological damage in a dose-dependent manner.Further tests showed that APAP-induced hepatic lipid peroxidation was reduced significantly by BP-1 pretreatment,and glutathione depletion was ameliorated obviously.CONCLUSION:BP-1 can effectively protect C57BL/6J mice from APAP-induced hepatotoxicity,and reduction of oxidative stress might be part of the protection mechanism.

Kinetic Modeling of Methanol to Olefins(MTO)Process on SAPO-34 Catalyst

A kinetic model of MTO process over the SAPO-34 catalyst considering the effect of water and coke deposition has been proposed.The model takes into account three steps of the MTO reaction in which the products cover 5 lumped components.The water in the feed not only reduces the concentration of methanol but also alleviates the deactivation of SAPO-34 catalyst.The kinetic parameters have been estimated by the least square method.It has been proved that the calculated values in the kinetic model are in good agreement with the experimental values.

Comparison of Two Different Protocols for Induction of Parturition in Heifers with or without Estradiol Benzoate

Objectives of this study were to investigate the efficacy of dexamethasone in combination with estradiol benzoate in controlled induction of parturition in heifers, especially in the subjects of retained fetal membranes and dystocia caused by fetal oversize. A total number of 100 Holstein-Friesian heifers aged 24-25 months, mean weight 450 kg and body condition score of 3-4 from a dairy herd located in the suburb of Tabriz with similar nutrition and management systems were allocated at random into two groups. Group A （Control, n = 50） heifers, after passing the minimum 270 d of pregnancy were injected with 30 mg dexamethasone IM. Group B （Treatment, n = 50） heifers with the same period of pregnancy received 30 mg dexamethasone plus 20 mg estradiol benzoate IM on the same days of pregnancy. The overall durations of initial treatments to induction of parturition were （41.50 ~ 2.65） h in group A and （37.50 ：i： 1.27） h in group B. In group A, more dystocia cases were observed than in group B. After parturition, group A showed a higher percentage of retention of fetal membranes as well as the calf mortality and dystocia compared to group B. The differences between two groups were statistically significant （P 〈 0.05）. In conclusion, our results indicate that induction of parturition by estradiol benzoate and dexamethasone together will be more effective than dexamethasone alone because of the less retention of fetal membranes, easy calving and shorter time from induction to parturition.

Kinetics for hydrogen production by methanol steam reforming in fluidized bed reactor

Hydrogen is one of the best energy carriers.Fluidized bed reactor provides a promising approach for hydrogen production. To describe the hydrogen generating rate with methanol steam reforming in fluidized bed reactor quantitatively, dual-rate kinetic models of the reactions with exponent form were developed, including that of steam reforming reaction(SR) and decomposition reaction(DE).The reaction rate per unit mass of catalyst was related to partial pressures of components. The exponentials in kinetic equations were obtained by linear least-squares method based on the experimental data. The variance homogeneity test(F test) shows that the dynamic models are feasible with high accuracy, which can be used to predict the generating rate of hydrogen under different reaction temperatures and feed flow rates in fluidized bed reactor. The SR and DE activation energy obtained indicates that ESR\ EDE, which can explain the previous observation that the CO_2 selectivity decreased with the temperature increase.

Enhanced antitumor effect of TM208 in combination with 5-fluorouracil in H_(22) transplanted mice

4-Methylpiperazine-l-carbodithioc-acid-3-cyano-3,3-diphenylpropyl ester hydrochloride（TM208）,a newly synthesized dithiocarbamate derivative,exhibits antitumor effect in vivo with low toxicity.However,the antitumor effect of TM208 in combination with drugs in clinical use for cytotoxic chemotherapy has not been identified.In our study,the antitumor effects and toxicities of TM208 in combination with cisplatin（DDP）,cyclophosphamide（CTX） and 5-fluorouracil（5-Fu）,respectively,were evaluated in vivo using a transplanted solid-type hepatocarcinoma H_（22） mice model.The results suggested that 5-Fu（5 mg/kg/2d） potentiated the antitumor effect of TM208（100 mg/kg/d） with significantly higher tumor inhibition rates（P0.01） and a slight elevation of toxicity;however,DDP and CTX in combination with TM208 did not exhibit similar enhanced antitumor effect.For further investigation,we found that the TM208 and 5-Fu combination therapy led to G_2/M cell cycle arrest of tumor cells in vivo by downregulating the protein expression of cyclin Bl,cdc2,cdk7,and upregulating the expression of p21 and p53.The protein expression levels of cyclin Dl and cyclin E were also downregulated in tumor cells treated with TM208 and 5-Fu,while those of cdk4 and cdk2 remained unchanged.The change of mRNA expression level of cdc2 was consistent with that of its protein in each group,while the mRNA expression of cyclin B1 remained unchanged among each group.These results demonstrated the dosage regimen of TM208 for combination therapy and could serve as evidence for clinical use of TM208 as an antineoplastic drug.