ABSTRACT
Cyclohexene is an important intermediate during the oxidation of cycloalkanes, which comprise a significant portion of real fuels. Thus, experimental data sets and kinetic models of cyclohexene play an important role in the understanding of the combustion of cycloalkanes and real fuels. In this work, an experimental and kinetic modeling study of the high-temperature ignition of cyclohexene is performed. Ignition delay time (IDT) measurements are carried out in a high-pressure shock tube (HPST). The studied pressures are 5, 10, and 20 bar; the equivalence ratios are 0.5, 1.0, and 2.0; and the temperatures range from 980 to 1400 K for IDT in HPST. It is shown that the IDTs of cyclohexene exhibit Arrhenius behaviors as a function of temperature, and the IDTs decrease as the equivalence ratio and pressure increase. The experimental results are simulated using three previous detailed kinetic mechanisms and an updated detailed mechanism in this work. The updated detailed kinetic mechanism exhibits good agreement with experimental results. Reaction path analysis and sensitivity analysis are performed to provide insights into the chemical kinetics controlling the ignition of cyclohexene. The results demonstrate that different detailed kinetic mechanisms are significantly different, and there are still no unified conclusions about the major reaction path for cyclohexene oxidation. However, it is worth noting that the abstraction reaction by oxygen at the allylic site and the submechanism of cyclopentene are of significant importance for the accurate prediction of IDTs of cyclohexene. The present experimental data set and kinetic model should be valuable to improve our understanding of the combustion chemistry of cycloalkanes.
ABSTRACT
Gastric cancer (GC) is a leading global health problem as it is the fifth most common cancer type and the third most common cause of cancer-related deaths worldwide. In most areas of the world, the incidence rate of GC is 1.5- to 3-fold higher in males than in females. The androgen receptor (AR) is an independent adverse prognostic factor in patients with GC. However, the mechanism by which AR regulates the progression of GC remains unclear. In this study, we found that AR expression was upregulated in 6/8 GC cell lines, and this expression was higher than that in immortalized gastric cells. AR expression was also higher in GC tissues than in adjacent tissues. Moreover, the ectopic expression of AR promoted the colony formation ability, migration and invasion of GC cells. In contrast, AR knockdown had the opposite effects on GC cell lines. Remarkably, we found that AR regulated cell cycle-related kinase (CCRK) expression through transcriptional mechanisms. The AR-CCRK axis promoted GC development through the phosphorylation of GSK3ß and ß-catenin. Furthermore, TCGA data revealed that high expression of AR or CCRK was related to poor prognosis in GC patients. The prognosis was significantly worse in patients with concurrent high AR and CCRK expression than in patients with low AR and CCRK expression. In conclusion, our study demonstrated that AR and CCRK acted as oncogenes in GC progression. However, their clinical roles require further exploration.
ABSTRACT
A method for the determination of trace elements such as lead, arsenic and mercury in cream cosmetics by total reflection X-ray fluorescence spectrometry (TXRF) with suspension sampling was developed. The mixed solvents of water,tetrahydrofuran,methanol and were used to disperse paste, cream, and additives of triton X-100 to promote the test liquid uniform. The test suspension fluid were taken into the sample carrier,drying and then introduced into TXRF. Poly(1-vinylpyrrolidone-co-vinyl acetate) (P(VP-co-VAc)) was added to curing sediments,inhibiting proliferation. Triton X-100 and P(VP-co-VAc) were found to have the function of reducing mercury loss in the drying process. The loss of elements in the drying process and the effect of triton X-100 and P(VP-co-VAc) were investigated. The effect of cream matrix, element interference, spectral line and the inner standard were discussed. The calibration curves for quantitative analysis were established using matrix standards, so the error of software decomposition peak and the error caused by thick sample were avoided within a certain range. In this work,the linear correlation coefficients of Pb,As and Hg calibration curve were greater than 0.998 The detection limit of Pb,As and Hg in the solution were 0.005,0.004 and 0.006 μg/mL,respectively. Relative standard diviations(RSDs, n=11) of Pb, As and Hg were 7.8%-14.9%,6.6%-13.3% and 7.6%-14.6% respectively. The results of Pb, As, and Hg in cream cosmetics determinated by this method agreed with those obtained from inductively coupled plasma atomic emission spectrometry and the value of standard reference material. The TXRF method was proved to be accurate,simple and valuable in determination of trace heavy metal ions in cosmetic samples.
ABSTRACT
AIMS: Calcification in adamantinomatous craniopharyngioma (ACP) is troublesome for surgical intervention. The aim of this study was to examine the osteogenic proteins that play important roles in the calcium deposition of the odontogenic/osteogenic tissues in craniopharyngioma. METHODS AND RESULTS: Craniopharyngiomas (n = 89) were investigated for the presence and expression pattern of the osteoinductive/odontoinductive factor bone morphogenetic protein-2 (Bmp2) and two osteoblastic differentiation makers, Runt-related transcription factor-2 (Runx2) and Osterix, using immunohistochemistry and Western blotting. Our results showed that Bmp2, Runx2 and Osterix levels increased in cases with high calcification and correlated positively with the degree of calcification in ACP, whereas they showed little or no expression in squamous papillary craniopharyngioma. In ACP, Bmp2 was expressed primarily in the stellate reticulum and whorl-like array cells; Runx2 and Osterix tended to be expressed in calcification-related epithelia, including whorl-like array cells and epithelia in/around wet keratin and calcification lesions. CONCLUSIONS: Our study indicated, for the first time, that osteogenic factor Bmp2 may play an important role in the calcification of ACP via autocrine or paracrine mechanisms. Given the presence of osteogenic markers (Runx2 and Osterix), craniopharyngioma cells could differentiate into an osteoblast-like lineage, and the process of craniopharyngioma calcification resembles that which occurs in osteogenesis/odontogenesis.
