Temperature dependence of circular DNA topological states

Circular double stranded DNA has different topological states which are defined by their linking numbers. Equilibrium distribution of linking numbers can be obtained by closing a linear DNA into a circle by ligase. Using Monte Carlo simulation, we predict the temperature dependence of the linking number distribution of small circular DNAs. Our predictions are based on flexible defect excitations resulted from local melting or unstacking of DNA base pairs. We found that the reduced bending rigidity alone can lead to measurable changes of the variance of linking number distribution of short circular DNAs. If the defect is accompanied by local unwinding, the effect becomes much more prominent. The predictions can be easily investigated in experiments, providing a new method to study the micromechanics of sharply bent DNAs and the thermal stability of specific DNA sequences. Furthermore, the predictions are directly applicable to the studies of binding of DNA distorting proteins that can locally reduce DNA rigidity, form DNA kinks, or introduce local unwinding.Comment: 15 pages in preprint format, 4 figure

Planning Method for Urban Subway Park-and-Ride Station and Parking Berth

For satisfying the growing demand of parking in urban area and relieving traffic congestion in downtown, under the condition of urban subway park-and-ride (P&R), the methods of site selection and scale calculation of parking lots are studied. Selecting Xi'an Rd. business circle in Dalian as study object, both survey and analysis of parking demand were conducted. Based on the principle of random equilibrium selection, the logit model of P&R demand was constructed. Then the forecasting models of parking demand both in downtown and peripheral zones were proposed respectively. Using the minimum travel distance of vehicles as the objective function, site selection optimization model of P&R station was constructed. The calculation methods of scale for parking lots in both downtown and P&R station were also processed. For the case of Xi'an Rd. business circle, not only the site of P&R station was planned, but the scale of parking berth was calculated. According to the plan and calculation, the total number of parking berth has increased from 3380 to 4011. Among the planned berths, 75.7 % are in the business circle and 24.3 % in P&R stations are outside downtown. Thus, the number of planned berths in the business circle has actually decreased by about 8 %. The research indicates that, for downtown with subway system, by reducing parking berths in downtown and increasing them in P&R stations outside the urban area, this planning method is more beneficial to relieve the problems of parking and traffic congestion in downtown than traditional method

Phytoremediation : a sustainable remedial method for soil contaminated by vanadium

Vanadium amassing in the soil increased with its widespread usage in multi-field. Elevated soil vanadium confers adverse effects on living organisms involved in plants, animals, and microorganisms. Moreover, vanadium can enter the human body through the food chain and lead to potential health risks stemming from its toxicity and carcinogenicity. Therefore, the remediation of soil contaminated by vanadium is imperative. Phytoremediation, a clean phytotechnology, is gaining increasing grace in modern society that prefers spirit-enjoy persuing. However, due to the blemishes of the remediation plants per se, the remediation efficiency relying on plants alone is not attractive. Therefore, the strengthened screening of vanadium accumulator and hyperaccumulator plants should step forward. Simultaneously, it is necessary to improve phytoremediation efficiency by some complementary measures, such as inoculating plant growth-promoting bacteria, vanadium reducing bacteria, and the proper application of plant growth regulators. Overall, microbe-assisted and moderate usage of plant growth-promoting factors are promising for the phytoremediation of vanadium-contaminated soil

The impact on the soil microbial community and enzyme activity of two earthworm species during the bioremediation of pentachlorophenol-contaminated soils

The ecological effect of earthworms on the fate of soil pentachlorophenol (PCP) differs with species. This study addressed the roles and mechanisms by which two earthworm species (epigeic Eisenia fetida and endogeic Amynthas robustus E. Perrier) affect the soil microbial community and enzyme activity during the bioremediation of PCP-contaminated soils. A. robustus removed more soil PCP than did E. foetida. A. robustus improved nitrogen utilisation efficiency and soil oxidation more than did E. foetida, whereas the latter promoted the organic matter cycle in the soil. Both earthworm species significantly increased the amount of cultivable bacteria and actinomyces in soils, enhancing the utilisation rate of the carbon source (i.e. carbohydrates, carboxyl acids, and amino acids) and improving the richness and evenness of the soil microbial community. Additionally, earthworm treatment optimized the soil microbial community and increased the amount of the PCP-4-monooxygenase gene. Phylogenic classification revealed stimulation of indigenous PCP bacterial degraders, as assigned to the families Flavobacteriaceae, Pseudomonadaceae and Sphingobacteriacea, by both earthworms. A. robustus and E. foetida specifically promoted Comamonadaceae and Moraxellaceae PCP degraders, respectively

METHODS FOR ESTIMATING VEHICLE QUEUES AT A MARINE TERMINAL: A COMPUTATIONAL COMPARISON

A long queue of vehicles at the gate of a marine terminal is a common traffic phenomenon in a port-city, which sometimes causes problems in urban traffic. In order to be able to solve this issue, we firstly need accurate models to estimate such a vehicle queue length. In this paper, we compare the existing methods in a case study, and evaluate their advantages and disadvantages. Particularly, we develop a simulation-based regression model, using the micro traffic simulation software PARAMIC. In simulation, it is found that the queue transient process follows a natural logarithm curve. Then, based on these curves, we develop a queue length estimation model. In the numerical experiment, the proposed model exhibits better estimation accuracy than the other existing methods

N′-[(E)-2-Hydroxy­benzyl­idene]-5-methyl­isoxazole-4-carbohydrazide monohydrate

In the structure of the title compound, C12H11N3O3·H2O, the dihedral angle formed by the benzene and isoxazole rings is 2.03 (8)°. The mol­ecular conformation is stabilized by an intra­molecular O—H⋯N hydrogen bond. In the crystal structure, mol­ecules are linked into a three-dimesional network by inter­molecular N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds, and by π–π stacking inter­actions involving adjacent benzene and isoxazole rings [centroid–centroid separation = 3.663 (2) Å]