低负荷下危急疏水与跨级疏水的能效评价研究

在正常工况下汽轮机回热系统中表面式加热器采用疏水逐级自流的连接方式,但在低负荷的工况下,由于加热器之间的压差变小,疏水逐级自流不畅,为防止加热器满水,需要通过危急疏水系统排放疏水。首次利用等效焓降方法,分别建立了低负荷工况下跨级疏水系统与危急疏水系统的能效分析模型,并与传统的危急疏水系统进行了经济性比较。在算例中,定量评价了低负荷工况下跨级疏水与危急疏水对经济性的影响。

Prognostic significance of preoperative and postoperative CK19 and CEA m RNA levels in peripheral blood of patients with gastric cardia cancer

AIM To evaluate the clinical and prognostic significance of preoperative and postoperative cytokeratin 19(CK19) and carcinoembryonic antigen(CEA) m RNA levels in peripheral blood of patients with gastric cardia cancer(GCC).METHODS We detected the preoperative and postoperative mR NA levels of CK19 and CEA in peripheral blood of 129 GCC patients by using reverse transcription-polymerase chain reaction and evaluated their clinical and prognostic significance by univariate Kaplan-Meier survival analysis and multivariate Cox proportional hazard analysis. A new prognostic model which stratified patients into three different risk groups was established based on the independent prognostic factors.RESULTS Elevated preoperative and postoperative CK19 and CEA mR NA levels in peripheral blood of GCC patients were associated with lymph node metastasis. Univariate analysis showed that tumor size, histological grade, depth of tumor invasion, lymph node metastasis, preoperative CK19 m RNA, and preoperative and postoperative CEA m RNA levels were correlated with the prognosis of GCC patients. The multivariate analysis showed that lymph node status(P = 0.018), preoperative CK19(P = 0.035) and CEA(P = 0.011) m RNA levels were independent prognostic factors for overall survival(OS). The 5-year OS rates for the low-, intermediate-, and high-risk groups were 48.3%, 22.6%, and 4.6%, respectively(P < 0.001).CONCLUSION Elevated preoperative CK19 and CEA mR NA levels may be regarded as promising biomarkers for predicting lymph node metastasis and poor prognosis in patients with GCC. This new prognostic model may help us identify the subpopulations of GCC patients with the highest risk.

Comparison on the phytoextraction efficiency of Bidens pilosa at heavy metal contaminated site in natural and electrokinetic conditions

The plant samples of Bidens pilosa were collected from a coal gangue vacant site and its surrounding area,located in central China,to study the remediation effect of the plant species on heavy metal(HM)contamination in both natural and electrokinetic(EK)conditions.The analytical results showed that the effect of phytoextraction and bioconcentration on the heavy metals in the sample of the EK group is more significant than those in the other control group.Compared with the results of natural condition,under the EK condition the concentrations of cadmium(Cd),lead(Pb),copper(Cu)and zinc(Zn)in the stems and leaves of the Bidens pilosa increased to 0.40 mg/kg,4.23 mg/kg,7.27 mg/kg,830.24 mg/kg,respectively,with their increments of 292%,1731%,141%,2076%.For root samples,the Cd,Pb,Cu and Zn concentrations increased to 0.52 mg/kg,4.36 mg/kg,10.87 mg/kg,and 98.12 mg/kg and the increase rates were 1034%,140%,29%,and 181%,respectively.The phytoextraction efficiency of the Bidens pilosa was significantly higher than that of control group.The removal efficiency of Cd,Pb,Cu and Zn in soil increased to 26%,72%,27%,and 79%with the EK applied.In addition,the mechanism of HM migration,extraction and enrichment in Bidens pilosa under the EK condition was discussed.

Preparation of chitosan-Epigallocatechin-3-O-gallate nanoparticles and their inhibitory effect on the growth of breast cancer cells

In this paper,we prepared the nanoparticle drug carrier system between nanoparticles chitosan and Epigallocatechin-3 O-gallate(EGCG)for breast cancer cell inhibiting application.For this drug carrier system,chitosan acts as a carrier and EGOG as a drug.Which were systematically characterized and thoroughly evaluated in terms of their inhibition rate and biocompatibility.We also did a cell scratch test and the result indicated that the chitosan EGCG nanoparticles have inhibitory effect on the growth of breast cancer cells.The inhibition rate could reach up to 21.91%.This work revealed that the modification of nanopartidles paved a way for specific biomedical applications.

Analysis of factors affecting microwave heating of natural gas hydrate combined with numerical simulation method

As a clean and abundant unconventional natural gas resource,natural gas hydrate(NGH)holds the characteristics of safety,high efficiency and sustainable exploitation,which helps to alleviate the energy shortage of China,reduce the foreign-trade dependence of oil and gas,and ensure the national energy security.Microwave heating is a significant method that has been used in natural gas hydrate exploration.By using the microwave heating,the NGH in the reservoir formations would be heated,decomposed and stimulated thanks to taking advantage of microwave heating's unique characters:efficiency,high speed,clean and pollution-free.This paper established the temperature under microwave heating gas hydrate distribution theory model,and by using the finite element method for simulating temperature field of microwave heating gas hydrate,this paper analyzed the natural gas hydrate in the microwave field temperature distribution in the influencing factors.Microwave has a significant heating effect on the hydrate reservoir in the immediate vicinity of wellbore,and it is not affected by the initial conditions of reservoir.The temperature can rise to above 50℃ within 1 h which is higher than the phase equilibrium temperature at the time of hydrate decomposition and is helpful to improve the decomposition rate of hydrate.The frequency is set at 915 MHz,and the feed port has a spiral arrangement with a length of 10 mm,which greatly expands the microwave heating range.