Understanding the molecular interaction and relaxation findings in amphiphilics on solution state using TDR

The dielectric behavior of stearic acid in 1,4-dioxane medium at various temperature 303 K–288 K and frequency regime (10 MHz–30 GHz) determined from the complex dielectric permittivity spectra obtained by Time Domain Reflectometry(TDR). In this frequency range, the dielectric study gives the electrostatic interaction as well as orientational polarizability of complex mixtures of long chain molecules significantly. Dielectric parameters were calculated from the complex spectra of the binary mixture by non linear least square fit method. The excess permittivity (ε^E), correlation factors were calculated for the binary system. Thermal parameters(ΔH-enthalpy, ΔS-entropy and ΔG-Gibbs free energy) were calculated and the direction of reaction is determined. The FTIR spectrum of the binary system recorded and the assignments are discussed. The FTIR spectral assignments confirm the molecular interactions.     

A simple analytical model of laser direct-drive thin shell target implosion

A high-neutron yield platform imploded by a thin shell target is generally built to probe nuclear science problems, and it has the advantages of high neutron yield, ultrashort fusion time, micro fusion zone, isotropic and monoenergetic neutron. Some analytical models have been proposed to interpret exploding-pusher target implosion driven by a long wavelength laser, whereas they are imperfect for a 0.35 μm laser implosion experiment. When using the 0.35 μm laser, the shell is ablated and accelerated to high implosion velocity governed by Newton's law, ablation acceleration and quasi-adiabatic compression models are suitable to explain the implosion of a laser direct-drive thin shell target. The new analytical model scales bang time, ion temperature and neutron yield for large variations in laser power, target radius, shell thickness, and fuel pressure. The predicted results of the analytical model are in agreement with experimental data on the Shenguang-III prototype laser facility, 100 kJ laser facility, Omega, and NIF, it demonstrates that the analytical model benefits the understanding of experiment performance and optimizing the target design of high neutron yield implosion.     

Measurement of(n,α)and(n,2n)reaction cross sections at a neutron energy of 14.92±0.02 MeV for potassium and copper with uncertainty propagation

Experimentally measured neutron activation cross sections are presented for the ⁶⁵Cu(n,0)^62mCu,⁴¹ K(n,a)^38Cl,and ⁶⁵Cu(n.2n)⁶⁴Cu reactions with detailed uncertainty propagation.The neutron cross secions were measured at an incident energy of 14.92±0.02 MeV,and the neutrons were based on the(d,n)a fusion reaction.The ²⁷ Al(n,a)²⁴Na reaction was used as a reference reaction for the normalization of the neutron flux.The pre-calib-rated lead-shielded HPGe detector was used to detect the residues'γ-ray spetra.The data from the measured cross sections are compared to the previously measured cross sections from the EXFOR database,theoretically calculated cross sections using the TALYS and EMPIRE codes,and evaluated nuclear data.     

Small-angle neutron scattering study on the stability of oxide nanoparticles in long-term thermally aged 9Cr-oxide dispersion strengthened steel

A 9Cr-oxide dispersion strengthened (ODS) steel was thermally aged at 873 K for up to 5000 h. The size distribution and chemical composition of the dispersed oxide nanoparticles were analyzed by small-angle neutron scattering under a magnetic field. Combined with transmission electron microscopy, Vickers micro-hardness tests and electron backscattered diffraction measurements, all the results showed that the thermal treatment had little or no effect on the size distributions and volume fractions of the oxide nanoparticles in the ferromagnetic matrix, which suggested excellent thermal stability of the 9Cr-ODS steel.     

Measurements of the 107Ag neutron capture cross sections with pulse height weighting technique at the CSNS Back-n facility

Silver indium cadmium (Ag-In-Cd) control rod is widely used in pressurized water reactor nuclear power plants, and it is continuously consumed in a high neutron flux environment. The mass ratio of ¹⁰⁷Ag in the Ag-In-Cd control rod is 41.44%. To accurately calculate the consumption value of the control rod, a reliable neutron reaction cross section of the ¹⁰⁷Ag is required. Meanwhile, ¹⁰⁷Ag is also an important weak r nucleus. Thus, the cross sections for neutron induced interactions with ¹⁰⁷Ag are very important both in nuclear energy and nuclear astrophysics. The (n,γ) cross section of ¹⁰⁷Ag has been measured in the energy range of 1-60 eV using a back streaming white neutron beam line at China spallation neutron source. The resonance parameters are extracted by an R-matrix code. All the cross section of ¹⁰⁷Ag and resonance parameters are given in this paper as datasets. The datasets are openly available at http://www.doi.org/10.11922/sciencedb.j00113.00010.     

Effect of pH and Protein Concentration on Rheological and Structural Behavior of Temperature-induced Bovine Serum Albumin Gels

The rheology of a temperature-induced protein bovine serum albumin gel is shown to strongly depend on the solution pH and protein concentration. Small-angle neutron scattering studies showed the presence of a fractal structure of the gels, resembling the aggregation of protein molecules and causing a three-dimensional network kind of arrangement. The fractal dimensions were observed to be constant and independent of the variation of pH and the protein concentration. The results of rheology and scattering experiments are correlated in terms of pH-dependent flexibility of flocs in the gels and hindrance to flow with concentration, while the structure of such flocs remains similar irrespective of the solution conditions.     

Comparison of Flameless Atomic Absorption Spectroscopy with Neutron Activation Analysis for Vanadium in Beach Asphalt

One of the major arguments against using trace metal characterization as a tool to identify oil spills is lack of reliability of the data. With this in mind, the precision of flameless atomic absorption spectroscopy and of neutron activation analysis was determined for vanadium in crude oil residues. Thirty crude oil residues (beach asphalts) were analyzed by both methods, and the results compared. For neutron activation analysis, the population mean was 195 ppm, and the standard deviation of the method was 5.38 ppm. For flameless atomic absorption spectroscopy, the population mean was 202 ppm, and the standard deviation 19.5 ppm.     

Vacuum fluctuation effects on hyperonic neutron star matter

The vacuum fluctuation （VF） effects on the properties of the hyperonic neutron star matter are investigated in the framework of the relativistic mean field （RMF） theory. The VF corrections result in the density dependence of in-medium baryon and meson masses. We compare our results obtained by adopting three kinds of meson-hyperon couplings. The introduction of both hyperons and VF corrections softens the equation of state （EoS） for the hyperonic neutron star matter and hence reduces hyperonic neutron star masses. The presence of the δ field enlarges the masses and radii of hyperonic neutron stars. Taking into account the uncertainty of meson-hyperon couplings, the obtained maximum masses of hyperonic neutron stars are in the range of 1.33M⊙-1.55M⊙.     

First neutron spectrometry measurement at the HL-2A Tokamak

A compact neutron spectrometer based on the liquid scintillator is presented for neutron energy spectrum measurements at the HL-2A Tokamak. The spectrometer was well characterized and a fast digital pulse shape discrimination software was developed using the charge comparison method. A digitizer data acquisition system with a maximum frequency of 1 MHz can work under an environment with a high count rate at HL-2A Tokamak. Specific radiation and magnetic shielding for the spectrometer were designed for the neutron spectrum measurement at the HL-2A Tokamak. For pulse height spectrum analysis, dedicated numerical simulation utilizing NUBEAM combined with GENESIS was performed to obtain the neutron energy spectrum. Subsequently, the transportation process from the plasma to the detector was evaluated with Monte Carlo calculations. The distorted neutron energy spectrum was folded with the response matrix of the liquid scintillation spectrometer, and good consistency was found between the simulated and measured pulse height spectra. This neutron spectrometer based on a digital acquisition system could be well adopted for the investigation of the auxiliary heating behavior and the fast-ion related phenomenon on different tokamak devices.