Structure and dynamics of an active polymer adsorbed on the surface of a cylinder.

The structure and dynamics of an active polymer on a smooth cylindrical surface are studied by Brownian dynamics simulations. The effect of an active force on the polymer adsorption behavior and the combined effect of chain mobility, length N, rigidity κ, and cylinder radius, R, on the phase diagrams are systemically investigated. We find that complete adsorption is replaced by the irregular alternative adsorption/desorption process at a large driving force. Three typical (spiral, helix-like, and rod-like) conformations of the active polymer are observed, dependent on N, κ, and R. Dynamically, the polymer shows rotational motion in the spiral state, snake-like motion in the intermediate state, and straight translational motion without turning back in the rod-like state. In the spiral state, we find that the rotation velocity ω and the chain length follow a power-law relation ω ∼ N-0.42, consistent with the torque-balance theory of general Archimedean spirals. And the polymer shows super-diffusive behavior along the cylinder for a long time in the helix-like and rod-like states. Our results highlight that the mobility, rigidity, and curvature of surface can be used to regulate the polymer behavior.

Route-Planning Method for Plant Protection Rotor Drones in Convex Polygon Regions.

Aiming at the problem of low operating efficiency due to the poor endurance of plant protection rotor drones and the small volume of pesticide carried, this paper proposes a route-planning algorithm for convex polygon regions based on the initial heading angle. First, a series of coordinate conversion methods ranging from the Earth coordinate system to the local plane coordinate system are studied. Second, in the local plane coordinate system, a route generation method based on subregion is proposed; therefore, multiple routes can be generated with different initial heading angles. Lastly, the optimal route and the best initial heading angle can be obtained after the comparison according to the three evaluation criteria: number of turns, route distance, and pesticide waste rate. The simulation results show that, compared with the common grid method, the route generation method based on subregion reduces the route distance and pesticide waste rate by 2.27% and 13.75%, respectively. Furthermore, it also shows that, compared with the route generated by the initial heading angle of 0°, the optimal route reduces the number of turns, route distance, and pesticide waste rate by 60%, 17.65%, and 38.18%, respectively. The route was optimized in three aspects and reached the best overall result using this method, which in turn proved its feasibility.

[Cognitive behavioral therapy for depression in advanced schistosomiasis patients].

OBJECTIVE: To evaluate the efficacy of cognitive behavioral therapy for depression in advanced schistosomiasis patients. METHODS: A total of 60 advanced schistosomiasis patients with major depressive disorder were divided into a combination therapy group (30 cases) who received sertraline plus cognitive behavior therapy and a monotherapy group (30 cases) who received sertraline only. Before the treatment and at the 1st, 2nd, 4th, 8th week after the treatment, the efficacy and safety were assessed with the HAMD17 item score and the related factor points and TESS. The effective rate, side effect rate and relapse rate in six months were calculated and compared between the two groups. RESULTS: At the end of 8th week after the treatment, the total scores of HAMD, factor scores of cognitive impairment, retardation factor scores and sleep disturbance factor scores in the 2 groups were statistically decreased compared with those before the treatment (P < 0.05 or P < 0.01). The factor scores in the combined therapy group were lower than those in the monotherapy group. The effective rate in the combination therapy group was 86.7% (26/30), and it was significantly higher than that in the monotherapy group (56.7%, 17/30), (chi2 = 6.65, P < 0.05). The doses of the drug were lower in the combination therapy group than those in the monotherapy group (t = 2.25, P < 0.05). Within six months, the relapse rate was 13.3% in the combination therapy group, and it was significantly lower than that in the monotherapy group (46.7%) (chi2 = 7.937, P < 0.025). The side effect rate was 23.3% in the combination therapy group and that was 26.7% in the monotherapy group, and there was no statistically significant difference between the two groups (P > 0.05). CONCLUSION: The combination therapy (drug combined with cognitive behavioral therapy) is effective in advanced schistosomiasis patients with depression, and it also can reduce the amount of medication and the relapse.

[Polymorphisms of methylenetetrahydrofolate reductase C677T and the risk of stomach cancer].

OBJECTIVE: In order to study the relation between polymorphisms of methylenetetrahydrofolate reductase C677T (MTHFR) and susceptibility of stomach cancer (SC). METHODS: We conducted a case-control study with 107 cases of SC and 200 population-based controls in Huaian city of Jiangsu province, China. The epidemiological data were collected, and DNA of peripheral blood leukocytes was obtained from all of the subjects. MTHFR genotypes were detected by PCR-RFLP method. RESULTS: (1) The frequency of MTHFR variant genotypes (C/T + T/T) among the cases (79.4%) was significantly higher than the controls (68.5%) (P = 0.041 6); the crude OR for SC was 1.78 (95% CI: 0.99 - 3.22). After adjustment for sex and age, the OR for SC was 1.89 (95% CI: 1.08 - 3.32). (2) Subjects who had MTHFR variant genotypes and having smoking habit were at a significantly higher risk of developing SC (OR = 7.72, 95% CI: 2.23 - 26.79) compared with those who had wild-type homozygotes (C/C) genotype and no smoking habit. Individuals who had variant genotypes and who had habit of frequent alcohol drinking were at an increased risk of developing SC (OR = 3.08, 95% CI: 1.30 - 7.23) compared with those with C/C genotype and low consumption of alcohol. As compared with subjects with C/C genotype and low consumption of alcohol and no smoking habit, individuals who had variant genotypes and who had habits of frequent alcohol drinking and smoking had 12.96 (95% CI: 2.76 - 70.46) folds risk developing SC. CONCLUSIONS: These results in the present study suggested that the polymorphisms of MTHFR C677T was associated with risk of developing SC, and there was a coordinated effect between MTHFR genotypes and habits of smoking and alcohol drinking in the development of SC.

hOGG1 Ser(326)Cys polymorphism and modification by environmental factors of stomach cancer risk in Chinese.

Oxidative stress is involved in many types of DNA damage, e.g., resulting in 8-hydroxyguanine adducts. Since a human counterpart exists for the yeast gene OGG1 (hOGG1) encoding an enzyme that repairs 8-hydroxyguanine, its polymorphism, Ser(326)Cys, might have potential as a genetic marker for cancer susceptibility. To investigate its association with stomach cancer risk and possible interactions with environmental factors, we conducted a case-control study of 101 stomach cancer cases and 198 controls using PCR-single-strand conformation polymorphism and a questionnaire approach. The proportional distribution of the Cys/Cys alleles did not differ between stomach cancer cases and controls, but subgroup analyses revealed that a frequent drinking habit elevated the odds ratio (OR) for stomach cancer in Cys/Cys compared to Ser/Ser and Ser/Cys carriers. The ORs with frequent consumption of pickled vegetables and meat tended to be higher in Cys/Cys than in Ser/Ser and Ser/Cys carriers, these interactions being on the borderline of statistical significance. Our findings suggest that the hOGG1 Ser(326)Cys polymorphism may alter the impact of some environmental factors on stomach cancer development. For confirmation, an additional study with a larger number of subjects is now required.

Interaction between cytochrome P-450 2E1 polymorphisms and environmental factors with risk of esophageal and stomach cancers in Chinese.

Because cytochrome P-450 2E1 (CYP2E1) is involved in metabolic activation of environmental chemical carcinogens, gene polymorphisms that alter its functions may be associated with cancer susceptibility. However, previous studies have revealed disconcordant results with regard to cancer risk. To investigate gene-environment interactions with the RsaI polymorphism of CYP2E1 in terms of risk of esophageal and stomach cancers, we conducted a case-control study with 93 esophageal and 98 stomach cancer cases and 196 population-based controls in a high-endemic area for these cancers of China. We assayed genomic DNA samples for RFLPs in the CYP2E1 by PCR amplification, followed by digestion with RsaI, and collected information on environmental factors by a questionnaire approach. Odds ratios were estimated with an unconditional logistic model, after adjustment for potential confounding factors. The proportional distribution of the homozygous common RsaI alleles did not differ between cancer cases of the esophagus (59.1%) and stomach (59.2%), and controls (61.7%). However, we found a significant positive interaction between the heterozygous and homozygous RsaI rare alleles and ever-smoking in the odds ratio for stomach cancer (P = 0.015). The interaction between the gene polymorphism and dietary factors, such as garlic consumption, was not observed in both cancer cases. These results suggest that gene-environment interactions between the CYP2E1 polymorphism and smoking may have the potential to alter the susceptibility for cancer development in the stomach.