[Learning curve of uniportal video-assisted thoracoscopic surgery lobectomy for the treatment of resectable lung cancer].

Objective: To analyze the learning curve of uniportal video-assisted thoracoscopic surgery (VATS) lobectomy for the treatment of resectable lung cancer. Methods: The clinical data of 160 patients with resectable lung cancer who underwent uniportal VATS lobectomy by a single surgical team between May 2016 and April 2017 at Department of Thoracic Surgery, the First Affiliated Hospital of the University of Science and Technology of China were analyzed retrospectively. The study group consisted of 90 male and 70 female patients with age of 28 to 84 years (median: 62 years). The patients were divided into four groups from group A to D according to chronological order. The operation time, incision length, intraoperative blood loss, number of dissected lymph nodes and nodal stations, the proportion of changes in operation mode, postoperative complications, chest drainage duration and hospitalization time were individually compared among the four groups by variance analysis and χ(2) test. Results: The 4 groups were similar in terms of incision length, chest drainage duration, number of dissected lymph nodes and nodal stations and postoperative hospitalization time (P>0.05). The difference of the operation time ((185.9±17.9) minutes vs. (139.9±10.7) minutes vs.(128.7±7.8) minutes vs.(124.0±9.3) minutes, F=219.605, P=0.000), intraoperative blood loss ((233.9±135.8) ml vs. (126.8±18.1) ml vs. (116.4±22.6) ml vs.(112.8±25.3) ml, F=26.942, P=0.000), the proportion of changes in operation mode (17.5% vs.7.5% vs. 5.0% vs. 5.0%, χ(2)=8.300, P=0.040), and the incidence of postoperative complications (27.5% vs. 10.0% vs. 10.0% vs. 7.5%, χ(2)=8.643, P=0.034) among the 4 groups was statistically significant. Conclusions: Uniportal VATS lobectomy can be safely and feasibly performed for resectable lung cancer, learning curve for uniportal VATS lobectomy is approximately 40 cases. Operation time, intraoperative blood loss, postoperative complications and the proportion of changes in operation mode can be used as the main measures during surgery.

[A prospective comparative study examing the impact of uniportal and three portal video-assisted thoracic surgery on short-term quality of life in lung cancer].

Objective: To evaluate the effect of the postoperative short-term quality of life between uniportal and three portal video-assisted thoracic surgery for radical lung cancer resection. Methods: The perioperative data and short-term quality of life of 120 patients received uniportal and three portal video-assisted thoracic surgery for radical lung cancer resection were analyzed from September to November 2017 at Department of Thoracic Surgery, the First Affiliated Hospital of University of Science and Technology of China. There were 64 male and 56 female patients aging of (62±10) years (ranging from 28 to 82 years). There were 60 cases received uniportal (uniportal group) and 60 cases received three portal video-assisted thoracic surgery (three-portal group). Quality of life by measurement of functional and symptom scales was assessed before surgery at baseline, and 1, 2, 4, and 8 weeks after the operation. The t test, χ(2) test, Fisher exact test and Wilcoxon rank-sum test were used to compare the date between the 2 groups. Repeated measurement variance was used for comparison of the quality of life at different time points. Results: There were no statistically significant differences in the clinicopathological features of the two groups (P>0.05). Intraoperative bleeding volume ((92±85) ml vs. (131±91) ml, t=2.387, P=0.019), postoperative catheter time ((4.4±3.1) days vs. (6.0±3.9) days, t=2.401, P=0.018), and postoperative hospitalization time ((6.2±4.0) days vs. (8.3±4.6) days, t=2.626, P=0.010) in the patients with uniportal group were less than that in three-portal group. Preoperative functional areas, symptom areas and overall health scores were similar in the two group. The functional areas such as physical function, role function, emotional function and social function and overall health status of uniportal group were significantly higher than those of three-portal group in postoperative time, while the fatigue and pain of uniportal group were significantly lower than that of three-portal group. Conclusions: Uniportal video-assisted thoracic surgery can achieve the same safety and radical of three-portal video-assisted thoracic surgery. It has advantages in intraoperative bleeding volume, postoperative time after operation, hospitalization time and postoperative life quality.

[A serum lipidomic study of patients with non-alcoholic fatty liver disease].

Objective: To investigate the serum lipidomic profile in patients with nonalcoholic fatty liver disease (NAFLD), and to analyze the lipid metabolism characteristics of NAFLD. Methods: The subjects were divided into control group (23 patients) and pathologically confirmed NAFLD group (42 patients), and ultra-high-performance liquid chromatography-tandem mass spectrometry was used to measure serum lipidomic metabolites. The partial least squares-discriminant analysis (PLS-DA) model was established to analyze the differences in lipid metabolism with reference to the univariate analysis. The t-test and Mann-Whitney U test were used for data analysis. Results: A total of 239 lipids were identified and qualitative and quantitative analyses were performed. The PLS-DA model (R2 = 0.753, Q2 = 0.456) and the univariate analysis showed that 77 lipids were metabolized differentially between the NAFLD group and the control group (VIP > 1, P < 0.05), including free fatty acid, phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, lysophosphatidylcholine, lysophosphatidylinositol (LPI), choline plasmalogen (PlsCho), ethanolamine plasmalogen (PlsEtn), ceramide (Cer), sphingomyelin, and triglyceride (TG). Compared with the control group, the NAFLD group had significant increases in monounsaturated fatty acids (increased by 39%, t = -3.954, P < 0.05) and TGs (increased by 36%, Z = -2.662, P < 0.05), mainly TGs with low numbers of carbon atoms and unsaturated bonds, while there were reductions in TGs with high numbers of carbon atoms and unsaturated bonds. In addition, compared with the control group, the NAFLD group had significant increases in the levels of LPI (increased by 223%, t = -3.858, P < 0.05) and Cer (increased by 21%, t = -2.481, P < 0.05) and significant reductions in PlsCho (reduced by 18%, t = 3.184, P < 0.05) and PlsEtn (reduced by 20%, t = 2.363, P < 0.05). Conclusion: There is a significant difference in lipid metabolism profile between NAFLD patients and healthy people, and a serum lipidomic analysis of NAFLD helps to further clarify the characteristics of lipid metabolism in patients with NAFLD.

Magnetic mediation effect of a C impurity in a Mn-doped Zn12O12 nanocluster: a case of multiple exchange interactions.

The stability and exchange interaction mechanism of a doped Zn12O12 cluster with Mn and C atoms were investigated by first-principles calculations. For the Mn-doped Zn12O12 cluster, it is identified that a superexchange interaction deriving the hybridization between the Mn 3d(2/x)-2/y and O 2p(xy) orbitals dominates the Mn(↑)-Mn(↓) antiferromagnetic coupling, although a direct exchange interaction deriving the Mn-Mn bonding is also found. In order to turn the Mn spin state in the Mn-doped Zn12O12 cluster, C doping is undertaken to change the magnetic interactions of these impurities. It is proved that the C incorporation into the Mn-doped Zn12O12 cluster destroys the short-ranged antiferromagnetic coupling, where multiple exchange interactions take over, including the direct exchange interaction and the kinetic p-d exchange interaction partially due to the geometric distortion and surface effect with dangling bonds (sp(2)-like hybrids). It is concluded that the kinetic p-d exchange interaction plays a dominant role in Mn/C-doped Zn12O12 clusters.

Intravenous fentanyl is exhaled and the concentration fluctuates with time.

Previous studies have reported that fentanyl is eliminated predominantly by hepatic biotransformation, and that some is eliminated unchanged in urine and stools. No reports have described the elimination of fentanyl via the lungs. In this study, exhaled gas samples from eight anaesthetized patients undergoing cardiac surgery were analysed using solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS). Results confirmed that fentanyl was exhaled by patients after intravenous administration, that the concentration of exhaled fentanyl fluctuated with time and peak concentrations were reached approximately 15 - 20 min after intravenous fentanyl administration. Thus, in addition to hepatic biotrans formation and elimination via urine and faeces, fentanyl is also eliminated unchanged by the lungs. The potential risk to operating theatre personnel from long-term exposure to low levels of exhaled anaesthetic agents following intravenous administration to patients during surgery warrants further research.

WITHDRAWN: Neoadjuvant chemotherapy versus none for resectable gastric cancer.

BACKGROUND: Gastric cancer is a major cause of cancer death, and many patients are only diagnosed when the cancer has reached an advanced stage. Neoadjuvant chemotherapy (NAC), that is, chemotherapy administered shortly before surgical treatment, could provide a method of increasing the possibility of complete resection and survival. OBJECTIVES: To evaluate the effect of neoadjuvant chemotherapy versus none for patients with resectable gastric cancer in terms of efficacy and toxicity. SEARCH STRATEGY: Electronic databases including Cochrane Library, MEDLINE, EMBASE, CancerLit, Chinese Biomedical Literature Database (CBMDISC) and ongoing clinical trials as well as handsearching of conference proceedings, were searched to retrieve relevant data. SELECTION CRITERIA: Randomized controlled clinical trials of neoadjuvant chemotherapy on resectable gastric cancer. DATA COLLECTION AND ANALYSIS: We identified a total of 36 published citations or meeting abstracts. Thirty-two items were excluded. Of the four remaining studies, three stated random allocation but the method of randomization was unclear. Two of these employed allocation concealment by sealed envelope which was controlled by an independent party. None of the trials was double blind. All trials presented a detailed description of the number of withdrawals, dropouts and losses to follow-up. MAIN RESULTS: Of the four clinical trials enrolled, there were 250 and 332 cases in total, with 106 and 126 deaths at the end of follow-up in the NAC and control group, respectively. The OR (odds ratio) was 1.05 (95%CI: 0.73-1.50), which was not statistically significant. Of the evaluable 129 patients receiving NAC, 28.7% demonstrated either a complete or a partial response. Two studies of NAC in resectable gastric cancer had resection rate data available for analysis The R0 resection rate in the NAC group was comparable to that in the control (OR: 0.96 (95%CI: 0.51-1.83)). The morbidity and mortality of NAC varied with the regimens used preoperatively. Of the 129 patients included in the analyzed studies, some acceptable toxicity was observed. AUTHORS' CONCLUSIONS: There is no definite evidence of the effectiveness of NAC in resectable gastric cancer, in terms of improvements in patient survival, in the trials we reviewed. Neoadjuvant chemotherapy should not be used routinely in clinical setting until further results from randomized clinical are available. Neoadjuvant chemotherapy of gastric cancer should be applied under the framework of clinical trials.

Neoadjuvant chemotherapy versus none for resectable gastric cancer.

BACKGROUND: Gastric cancer is a major cause of cancer death, and many patients are only diagnosed when the cancer has reached an advanced stage. Neoadjuvant chemotherapy (NAC), that is, chemotherapy administered shortly before surgical treatment, could provide a method of increasing the possibility of complete resection and survival. OBJECTIVES: To evaluate the effect of neoadjuvant chemotherapy versus none for patients with resectable gastric cancer in terms of efficacy and toxicity. SEARCH STRATEGY: Electronic databases including Cochrane Library, MEDLINE, EMBASE, CancerLit, Chinese Biomedical Literature Database (CBMDISC) and ongoing clinical trials as well as handsearching of conference proceedings, were searched to retrieve relevant data. SELECTION CRITERIA: Randomized controlled clinical trials of neoadjuvant chemotherapy on resectable gastric cancer. DATA COLLECTION AND ANALYSIS: We identified a total of 36 published citations or meeting abstracts. Thirty-two items were excluded. Of the four remaining studies, three stated random allocation but the method of randomization was unclear. Two of these employed allocation concealment by sealed envelope which was controlled by an independent party. None of the trials was double blind. All trials presented a detailed description of the number of withdrawals, dropouts and losses to follow-up. MAIN RESULTS: Of the four clinical trials enrolled, there were 250 and 332 cases in total, with 106 and 126 deaths at the end of follow-up in the NAC and control group, respectively. The OR (odds ratio) was 1.05 (95%CI: 0.73-1.50), which was not statistically significant. Of the evaluable 129 patients receiving NAC, 28.7% demonstrated either a complete or a partial response. Two studies of NAC in resectable gastric cancer had resection rate data available for analysis The R0 resection rate in the NAC group was comparable to that in the control (OR: 0.96 (95%CI: 0.51-1.83)). The morbidity and mortality of NAC varied with the regimens used preoperatively. Of the 129 patients included in the analyzed studies, some acceptable toxicity was observed. AUTHORS' CONCLUSIONS: There is no definite evidence of the effectiveness of NAC in resectable gastric cancer, in terms of improvements in patient survival, in the trials we reviewed. Neoadjuvant chemotherapy should not be used routinely in clinical setting until further results from randomized clinical are available. Neoadjuvant chemotherapy of gastric cancer should be applied under the framework of clinical trials.

Screening and analysis of bioactive compounds in traditional Chinese medicines using cell extract and gas chromatography-mass spectrometry.

As the cost of drug development is always many times more than that of drug discovery, predictive methods aiding in the screening of bioavailable drug candidates are of profound significance. In this paper, a novel method for screening bioactive compounds from traditional Chinese medicines (TCMs) was developed by using living cell extract and gas chromatography (GC)-mass spectrometer (MS). The method was validated by using elemene emulsion injection (EEI), a typical TCM with known active compound, to interact with murine ascites hepatocarcinoma cell strain with high metastatic potential (HCa-F). Finally, the method was applied to screen the bioactive compounds from multi-component zedoary turmeric oil and glucose injection (ZTOGI). After HCa-F cells was incubated in ZTOGI, ethyl acetate (EtOAc) was used to extract the compounds in the cells for GC-MS analysis. Fourteen compounds were detected in the desorption eluate of HCa-F cell extract of ZTOGI, and further identified by MS. Curzerene and beta-elemene were found to be two major bioactive compounds in ZTOGI. These results show that the method developed may be applied to quickly screen the potential bioactive components in TCMs interacting with the target cells.

Study of urinary 8-hydroxydeoxyguanosine as a biomarker of oxidative DNA damage in diabetic nephropathy patients.

Increased oxidative stress induced by hyperglycemia may contribute to the pathogenesis of diabetic complications. Urinary 8-hydroxydeoxyguanosine (8-OHdG) has been reported to serve as a sensitive biomarker of oxidative DNA damage and also of oxidative stress. This article studied oxidative DNA damage in patients with diabetic nephropathy and in healthy control subjects by urinary 8-OHdG evaluations. Contents of 8-OHdG in urine were analyzed by capillary electrophoresis with end-column amperometric detection (CE-AD) after a single-step solid-phase extraction (SPE). Levels of urinary 8-OHdG in diabetic nephropathy patients with macroalbuminuria was significant higher than in control subjects (5.72 +/- 6.89 micromol/mol creatinine versus 2.33 +/- 2.83 micromol/mol creatinine, P = 0.018). A significant difference of 24 h urinary 8-OHdG excretions exists between the patients with macroalbuminuria and the patients with normoalbuminuria (19.2 +/- 16.8 microg/24 h versus 8.1 +/- 1.7 microg/24 h, P = 0.015). There was a positive correlation between urinary excretion of 8-OHdG and glycosylated hemoglobin (HbA1c) (r = 0.287, P = 0.022). A weak correlation exists between the levels of 8-OHdG and triglyceride (r = 0.230, P = 0.074). However, the urinary 8-OHdG contents are not correlated with blood pressure and total cholesterol. The increased excretion of urinary 8-OHdG is seen as indicating an increased systemic level of oxidative DNA damage in diabetic nephropathy patients.

Helicobacter pylori prevalence and CagA status among children in two counties of China with high and low risks of gastric cancer.

BACKGROUND: Studies in adult populations in selected countries with widely varying rates of gastric cancer have shown a weak correlation between gastric cancer mortality rates and the prevalence of CagA+ strains of H. pylori. However, only limited data are available in ethnically homogenous populations with varying rates in the same region. METHODS; We compared the prevalence of H. pylori in general and of CagA+ strains in particular among children in Shandong Province, China in areas at high (Linqu County) and low risk (Cangshan County) of gastric cancer. H. pylori status among children aged 3 to 12 years was determined by 13C-UBT, and CagA status was determined by enzyme-linked immunosorbent assay (ELISA). Because of the difficulty in obtaining blood from young children aged 3 to 4 years and from some children aged 5 years, CagA status was determined among part of children 5 years old and children 6 to 12 years old. RESULTS; Among 98 children aged 3 to 12 years in Linqu, 68 (69.4%) was H. pylori-positive, as compared with 29 (28.7%) among 101 children in Cangshan. Among children positive for 13C-UBT, the proportion of the CagA+ strains were identified was 46 (88.5%) of 52 in Linqu and 13 (81.3%) of 16 in Cangshan, respectively. CONCLUSIONS: The prevalence of H. pylori was nearly three times higher among children in Linqu than in Cangshan, which may contribute to the large differential in gastric cancer rates for two neighboring populations in Shandong Province.

An intervention trial to inhibit the progression of precancerous gastric lesions: compliance, serum micronutrients and S-allyl cysteine levels, and toxicity.

Gastric cancer is the second most frequent cause of death from cancer in the world and the leading cause of death from cancer in China. In September 1995, we launched a randomized multi-intervention trial to inhibit the progression of precancerous gastric lesions in Linqu County, Shandong Province, an area of China with one of the world's highest rates of gastric cancer. Treatment compliance was measured by pill counts and quarterly serum concentrations of vitamin C, vitamin E and S-allyl cysteine. In 1999, toxicity information was collected from each trial participant to evaluate treatment-related side-effects during the trial. Compliance rates were 93% and 92.9% for 39 months of treatment with the vitamins/mineral and garlic preparation, respectively. The means for serum concentrations of vitamins C and E were 7.2 microg/ml and 1695 microg/dl among subjects in the active treatment groups compared with 3.1 microg/ml and 752 microg/dl among subjects in the placebo treatment group, respectively. No significant differences in side-effects were observed between the placebo treatment group and the vitamins/mineral and garlic preparation treatment groups during the 39-month trial period.

Inactivation of p53 sensitizes U87MG glioma cells to 1,3-bis(2-chloroethyl)-1-nitrosourea.

We examined the effect of p53 inactivation on the response of U87MG glioma cells to 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). These studies were motivated by three observations: (a) some human astrocytomas are sensitive to BCNU and some are resistant; (b) chemosensitive astrocytomas are more likely to be found in young adults whose tumors are more likely to harbor a p53 mutation; and (c) mouse astrocytes lacking the p53 gene are more sensitive to BCNU than wild-type cells. Here, we observed that p53 inactivation by transfection with pCMV-E6 sensitized U87MG cells to BCNU. Compared with control U87MG-neo cells with intact p53 function, the clonogenic survival of U87MG-E6 cells exposed to BCNU was reduced significantly. In U87MG-E6 cells, sensitization to BCNU was associated with failure of p21(WAF1) induction, transient cell cycle arrest in S phase, accumulation of polyploid cells, and significant cell death. In contrast, resistance to BCNU in U87MG-neo cells was associated with up-regulation of p53, prolonged induction of p21(WAF1), sustained cell cycle arrest in S phase, and enhancement of DNA repair. U87MG cells with disrupted p53 function were less able to repair BCNU-induced DNA damage and survive this chemotherapeutic insult. The question arises of whether p53 dysfunction might be a chemosensitizing genetic alteration in human astrocytic gliomas.

[Technique and advance of comprehensive two-dimensional gas chromatography].

Many analytical problems require more resolution than the conventional single column chromatographic technique can provide. In such cases the separation power can be enhanced by using more than one separation technique or mechanism. The sample is then dispersed in different time dimensions. The resolution obtained depends strongly on the difference between these dimensions. The highest resolution is gained when there is no correlation between the separations, the dimensions being orthogonal to each other. Comprehensive two-dimensional gas chromatography (GC x GC) provides a true orthogonal separation system in which a modulator serially couples two columns containing dissimilar stationary phases. It focuses and subsequently reinjects components eluting from the first column into the second one. The system generates a peak capacity that is approximately equal to the product of the peak capacities of the two individual separation systems. In this paper, technique and instrumental considerations of GC x GC are discussed. The three designs of contemporary GC x GC systems are presented and compared. A number of typical applications on complex samples such as petroleum products and environmental pollutants are also cited. Finally, the future perspectives of GC x GC are simply discussed.

[Development of a gas chromatographic column system for the on-line analysis of trace tetrahydrofuran in hexane].

A gas chromatographic system using home-made 7 microns thick cross-linked dimethylpolysiloxane columns for the on-line analysis of trace tetrahydrofuran in hexane in a rubber production facility was developed. The experimental parameters of the column system, including the temperature, flow rate as well as the back-flushing and heart-cutting program were investigated. The total column-switching program was suggested. The system has been successfully operated for more than one year with good resolution, stability and precision (RSD < 5%) in analyzing trace tetrahydrofuran (0-250 x 10(-6), V/V) for industrial process control in the rubber production facility.

[Advances in chromatography and related techniques in China--status report in 1998-1999].

This report covers developments in chromatography and related techniques in China during the period of 1998-1999. The papers published in 23 domestic and a few foreign periodicals which are closely related to chromatography, and presented at 1999 Beijing Conference and Exhibition on Instrumental Analysis and the 12th National Symposium of Chromatography are reviewed. Specific topic areas covered include gas chromatography (GC), high performance liquid chromatography (HPLC), capillary electrophoresis (CE) and capillary electrochromatography (CEC), solid phase extraction (SPE) and solid phase microextraction (SPME).

Gastric dysplasia and gastric cancer: Helicobacter pylori, serum vitamin C, and other risk factors.

BACKGROUND: Gastric cancer is generally thought to arise through a series of gastric mucosal changes, but the determinants of the precancerous lesions are not well understood. To identify such determinants, we launched a follow-up study in 1989-1990 among 3433 adults in Linqu County, China, a region with very high rates of gastric cancer. METHODS: Data on cigarette smoking, alcohol consumption, and other characteristics of the participants were obtained by interview in 1989-1990, when an initial endoscopy was taken. At study entry, antibodies to Helicobacter pylori were assayed in 2646 adults (77% of people screened), and levels of serum micronutrients were measured in approximately 450 adults. Follow-up endoscopic and histopathologic examinations were conducted in 1994. Antibodies to H. pylori, levels of serum micronutrients, and other baseline characteristics were compared between subjects whose condition showed progression to dysplasia or gastric cancer from study entry to 1994 and subjects with no change or with regression of their lesions over the same time frame. All P: values are two-sided. RESULTS: The presence of H. pylori at baseline was associated with an increased risk of progression to dysplasia or gastric cancer (odds ratio [OR] = 1.8; 95% confidence interval [CI] = 1.2-2.6). The risk of progression to dysplasia or gastric cancer also was moderately increased with the number of years of cigarette smoking. In contrast, the risk of progression was decreased by 80% (OR = 0.2; 95% CI = 0.1-0.7) among subjects with baseline ascorbic acid levels in the highest tertile compared with those in the lowest tertile, and there was a slightly elevated risk in those individuals with higher levels of alpha-tocopherol. CONCLUSIONS: H. pylori infection, cigarette smoking, and low levels of dietary vitamin C may contribute to the progression of precancerous lesions to gastric cancer in this high-risk population.

Blood type and family cancer history in relation to precancerous gastric lesions.

BACKGROUND: The increased odds of stomach cancer among subjects with blood type A have been reported in epidemiological studies. AIM: To study the relation of family history of gastric cancer and ABO blood type with precancerous gastric lesions in a high-risk area for stomach cancer. Subjects and setting We examined 3400 adults aged 35-64 in a population-based gastric endoscopic screening in a county in China with one of the highest rates of stomach cancer in the world. METHODS: In this cross-sectional study, data on family cancer history, ABO blood type and other characteristics of the participants were obtained by interview and blood test. Responses were compared between those with the most advanced gastric lesions, dysplasia (DYS) or intestinal metaplasia (IM), versus those with chronic atrophic gastritis (CAG) or superficial gastritis (SG). RESULTS: The prevalence odds ratio (OR) for blood type A relative to other types was 1.39 (95% CI : 1.12-1.73) for DYS and 1.28 (95% CI : 1.06-1.53) for IM. The OR associated with parental history of stomach cancer was 1.88 (95% CI : 1.20-2.95) for DYS, but the numbers were too small to evaluate aggregation among siblings. The combined OR associated with blood type A and a parental of history of gastric cancer was 2.61 (95% CI : 1.59-4.30) for DYS and 1.46 (95% CI : 0.93-2.31) for IM. CONCLUSIONS: The findings suggest that genetic factors play a role in developing precancerous gastric lesions.

[Column efficiency prediction of two dimensional chromatography by artificial neural network].

This paper used artificial neural network (ANN) modeling method to study the relationship between the column efficiency and the operating conditions. This method solved the problem that it is not easy to establish a quantitative model between the column efficiency and its main effecting factors using those traditional modeling methods, as the relationship is usually quite complex and non-linear in fact. The varied-pace BP (back-propagation) learning algorithm was adopted, and a three-layer weight-connected ANN model for a typical dual column system was established. The effective plate number representing the column efficiency acted as the output vectors, while the temperature of the pre-column, the temperature of the main column, the pressure difference between the columns and the vent rate acted as the input vectors. Then the model acquired was used to predict column efficiency (characterized by "effective plate number") under different operating conditions. The results showed that the model predicting value was in consistent with the value found. This work proved that ANN modeling method was suitable for the study on the relationship between the column efficiency of two-dimensional column chromatography system and the operating conditions.

[Advances in nonaqueous capillary electrophoresis].

Advances in nonaqueous capillary electrophoresis are reviewed with 71 references in this paper. Capillary electrophoresis is generally performed in aqueous buffer. In fact, it can provide some advantages to use organic solvent as a separation medium instead of water. The choice of organic solvent and electrolyte, the detection mode and solute-additive interactions are summarized. Furthermore, the separation of inorganic ions, neural compounds, organic acids, pharmaceuticals, metabolites and chiral substance is also described.

[Investigation of a gas chromatographic column system for the on-line analysis of gaseous components in de-propane tower of pyrolysis equipment].

Multi-dimensional gas chromatograph has become an important process analyzer due to the advantages of high resolution and fast speed. According to the production requirement, a gas chromatographic column switching system has been investigated for the on-line analysis of gaseous components from high-pressure and lower-pressure de-propane towers of pyrolysis equipment. By using two different injection times on three injectors, and fore-flush and back-flush techniques, C2-hydrocarbons, propane, propene, methylacetylene, propadiene and C4-hydrocarbons can be separated on 7 columns in 7 minutes. The practical application showed the developed column system is suitable for the on-line monitoring of the production process.