Nuclear safety in the unexpected second nuclear era.

Nuclear energy development has entered an unexpected second nuclear era, which is mainly driven by developing countries. Despite major efforts to pursue a safe nuclear energy system in the first nuclear era, severe nuclear accidents occurred. A basic problem is that we do not have an adequate understanding of nuclear safety.

The design of a direct charge nuclear battery with high energy conversion efficiency.

Direct charging nuclear batteries (DCNB) have the potential of being widely used to meet the special requirements in the area of aerospace and ocean. The current application of direct charging nuclear batteries is restricted by the low energy conversion efficiency, commonly less than 10%. This low efficiency is limited mainly by issues of low source efficiency and shunt factor among others, such as collection and geometry factors.

[Development and Validation of Dynamic Intensity Modulated Accurate Radiotherapy System KylinRay-IMRT].

KylinRay-IMRT is the advanced radiotherapy treatment planning module of accurate radiotherapy system (KylinRay) aiming to provide accurate and efficient plan design platform. In this paper the system design, main functions and key technologies of KylinRay-IMRT were introduced. KylinRay-IMRT supports three dimensional conformal radiotherapy (3D-CRT), intensity modulated radiotherapy (IMRT) and many other types of treatment plan design with function modules including patient data management, image registration and fusion, image contouring, image three dimensional reconstruction and visualization, three dimensional conformal radiotherapy planning, intensity modulated radiotherapy planning, plan evaluation and comparison, and report print.

Halogen bonding versus hydrogen bonding induced 2D self-assembled nanostructures at the liquid-solid interface revealed by STM.

We design a bifunctional molecule (5-bromo-2-hexadecyloxy-benzoic acid, 5-BHBA) with a bromine atom and a carboxyl group and its two-dimensional self-assembly is experimentally and theoretically investigated by using scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. The supramolecular self-organization of 5-BHBA in two different solvents (1-octanoic acid and n-hexadecane) at the liquid-solid interface at different solution concentrations is obviously different due to the cooperative and competitive intermolecular halogen and hydrogen bonds. Three kinds of nanoarchitectures composed of dimers, trimers and tetramers are formed at the 1-octanoic acid/graphite interface based on -COOHHOOC-, triangular C[double bond, length as m-dash]OBrH-C, -BrO(H), BrBr, and OH interactions.

Cooperation and competition between halogen bonding and van der Waals forces in supramolecular engineering at the aliphatic hydrocarbon/graphite interface: position and number of bromine group effects.

Herein, the photophysical properties of two π-conjugated thienophenanthrene derivatives (6,9- and 5,10-DBTD) are reported. Their self-assembled monolayers in aliphatic hydrocarbon solvents under different concentrations were investigated by scanning tunneling microscopy on a graphite surface. The STM results revealed that the self-assembled structures of the two geometrical isomers exhibited absolutely different behaviors.

Controllable Orientation of Ester-Group-Induced Intermolecular Halogen Bonding in a 2D Self-Assembly.

Halogen bonding with high specificity and directionality in the geometry has proven to be an important type of noncovalent interaction to fabricate and control 2D molecular architectures on surfaces. Herein, we first report how the orientation of the ester substituent for thienophenanthrene derivatives (5,10-DBTD and 5,10-DITD) affects positive charge distribution of halogens by density functional theory, thus determining the formation of an intermolecular halogen bond and different self-assembled patterns by scanning tunneling microscopy. The system presented here mainly includes heterohalogen X···O═C and X···S halogen bonds, H···Br and H···O hydrogen bonds, and I···I interaction, where the directionality and strength of such weak bonds determine the molecular arrangement by varying the halogen substituent.

Effects of the position and number of bromine substituents on the concentration-mediated 2D self-assembly of phenanthrene derivatives.

The effects of the position and number of bromine substituents on the self-assembled patterns of phenanthrene derivatives by changing multiple weak intermolecular interactions were investigated at the 1-octanoic acid/graphite interface at different concentrations by scanning tunneling microscopy. Two Br substituted DBHP molecules (2,7-DBHP, 3,6-DBHP) and BHP without a Br group formed a linear lamellar pattern by the van der Waals interactions between the alkoxyl chains in each lamella at high concentrations, which forces the phenanthrene derivatives to self-organize in a π-π stacked edge-on conformation. On decreasing the solution concentration, owing to the molecule-molecule van der Waals force and BrBr halogen bonds or the molecule-solvent cooperative BrO (C[double bond, length as m-dash]O) hydrogen and BrHO-hydrogen bonds, 2,7-DBHP molecules were found to form two kinds of network structures, whereas 3,6-DBHP molecules formed only a zigzag pattern due to the intermolecular BrBr van der Waals type interactions.

Dynamic evaluation of environmental impact due to tritium accidental release from the fusion reactor.

As one of the key safety issues of fusion reactors, tritium environmental impact of fusion accidents has attracted great attention. In this work, the dynamic tritium concentrations in the air and human body were evaluated on the time scale based on accidental release scenarios under the extreme environmental conditions. The radiation dose through various exposure pathways was assessed to find out the potential relationships among them.

High-spin states and level structure in stable nucleus strontium-84.

High-spin states of (84)Sr are populated through the reaction (70)Zn ((18)O, 4n) (84)Sr at the beam energy of 75 MeV. The measurements of excitation functions, γ-γ coincidences, directional correlations of oriented states (DCO) ratios and γ-transition intensities are performed using eight anticompton HPGe detectors and one planar HPGe detector. Based on the experimental results, we establish a new level scheme of (84)Sr, in which 12 new states and nearly 30 new γ-transitions are identified in the present work.

Comparison of serum from gastric cancer patients and from healthy persons using FTIR spectroscopy.

Since serum can reflect human beings' physiological and pathological conditions, FTIR spectroscopy was used to compare gastric cancer patients' serum with healthy persons' serum in this study. The H2959/H2931, H1646/H1550, H1314/H1243, H1453/H1400 and H1080/H1550 ratios were calculated, among these ratios, the H2959/H2931 ratio might be a standard for distinguishing gastric cancer patients from healthy persons. Then curve fitting was processed using Gaussian curves in the 1140-1000 cm(-1) region, and the result showed that the RNA/DNA ratios of gastric cancer patients' serum were obviously lower than those of healthy persons' serum.

SU-E-T-504: Incident Fluence Reconstruction Based on Monte Carlo Finite-Size Pencil Beam Model for Dose Guided Radiation Therapy.

Purpose: In dose guided radiation therapy, incident fluence is one of the important parameters for both influence verification and dose reconstruction. The objective of this investigation was to develop a method to obtain the incident fluence for dose reconstruction in dose guided radiation therapy (DGRT).

Methods: An incident fluence reconstruction model based on Monte Carlo Finite-size pencil beam (MCFSPB) model and "Matthew Effect" Conjugate-gradient (CG) algorithm was developed, where the MCFSPB model was developed by FDS Team (www.

SU-E-T-204: A Prototype of Dose-Guided Radiation Therapy.

Purpose: With the advancement in dosimetric devices and the development of dose reconstruction algorithm, the implementation of dose-guided radiation therapy (DGRT) is feasible. In order for DGRT to be performed clinically, a prototype of DGRT was developed in this study.

Methods: The prototype adopted a strategy for DGRT that adjusted the treatment plan for future fractions to compensate for dosimetric errors from past fractions, which included four main functional modules: management of patient plan information, dose reconstruction, dose evaluation, plan adjustment.

Patient positioning error measurement based on dynamic template matching techniques.

The decrease of accuracy in patients' repeated positioning in radiotherapy due to body's transformation is considered and a positioning error measurement method using dynamic template matching technique is brought forward in this paper. This method is an improvement of the matching method to correct positioning error based on the CT digitally reconstructed radiograph(DRR), which uses the video reconstructed 3D surface model that can reflect the body's transformation as the matching template instead of DRR. This method can not only improve the positioning accuracy but also eliminate the adverse influence brought by body's transformation.

A multi-objective hybrid genetic based optimization for external beam radiation.

A multi-objective hybrid genetic based optimization algorithm is proposed according to the multi-objective character of inverse planning. It is based on hybrid adaptive genetic algorithm, which combines the simulated annealing, uses adaptive crossover and mutation, and adopts niched tournament selection. The result of the test calculation demonstrates that excellent converge speed can be achieved using this approach.

Effect of CT Image-Based Voxel Size On Monte Carlo Dose Calculation.

Currently, the conventional empirical or semi-empirical dose calculation algorithms for radiation treatment planning system have been selected as dose engines. The accuracy of these dose calculation algorithms is limited. The main problem is that they fail to adequately consider the lateral transport of radiation or loss of electronic equilibrium near interface between two heterogeneous mediums.

Repeated positioning in accurate radiotherapy based on virtual net technique and contrary reconstruction scheme.

This paper presents a new repeated positioning system for external radiotherapy. A new scheme is proposed to rebuild patient's body surface 3-D image based on simple stereo vision model and virtual net technique, which improves the reconstruction precision of the template. For the calculation of the positioning error, the contrary reconstruction scheme is adopted and the positioning speed is greatly improved.

'A finite size pencil beam for IMRT dose optimization'--a simpler analytical function for the finite size pencil beam kernel.

A simple and finite-termed analytical function for the finite size pencil beam kernel was constructed. The dose cross-profile of a semi-infinite field with field edge at x = 0 can be well fitted by the Boltzmann function. The pencil beam cross-profile of width 2x(0) can be obtained as the difference between two semi-infinite fields shifted by 2x(0).

An integrative radiation protection control system based on a CAN bus for the HT-7U tokamak fusion device.

A radiation protection control system has been designed, based on distributed computers and consideration of the features of the radiation source of the HT-7U fusion experimental device, for protecting the workers and the public against neutron and photon radiation, and especially for ensuring that workers cannot unexpectedly enter an area of high radiation level in any case. A multisubsystem (irradiation monitoring subsystem, access control subsystem, safety interlock subsystem and other related facilities) integration concept is proposed for the design. This system has been implemented on the basis of the up-to-date industrial field bus CAN, featuring simplicity and flexibility of installation and maintenance, capability for real-time long distance communication and multi-master protocol.

Diffusion of Eu(III) in compacted bentonite-effect of pH, solution concentration and humic acid.

The effect of pH, Eu(III) solution concentration and humic acid on the diffusion of Eu(III) in compacted bentonite (rho(b) = 1000 +/- 30 kg/m(3)) was studied with "in-diffusion" method at an ionic strength of 0.1M NaClO(4). The results (K(d) values from the first slice and theoretical calculation, apparent and effective diffusion coefficients) derived from the new capillary method are in good agreement with the literature data under similar conditions, and fit the Fick's second law very well.