Monolith Passive Adsorbers Prepared with Hydrophobic Porous Silica Rods Coated with Hydrogel

This work focuses on the synthesis and characterization of porous silica monolith-based adsorbent materials. Materials with bimodal porosity (macro and meso) were prepared through a sol–gel process. The capacity of adsorption of organic molecules was ensured by grafting of hydrophobic organic coating on the silica surface. Alkylsilane chains or lauryl acrylate polymer were used for this purpose. The adsorption kinetic behavior of the produced materials was assessed through benzophenone adsorption studies in aqueous media. The results have shown that the macropore size of the monoliths had no effect on the adsorption capacity. The thicker organic layer prepared by polymerization of lauryl acrylate has decreased the adsorption kinetics without affecting the total adsorption capacity. The over-coating with additional external layer of hydrogel further slowed the diffusion of benzophenone thus better matches the passive-sampler requirements.     

Relation between the E(5) symmetry and the interacting boson model beyond the mean-field approximation

In a unified algebraic scheme,we investigate the relation between the E(5) symmetry and the interacting boson model beyond the mean-field level.The results indicate that the E(5) symmetry is actually in between the critical point of the U(5)-O(6) transition and the O(6) limit but it is fairly close to the former based on the phase diagram of the interacting boson model at the large boson number limit.In addition,an algebraic Hamiltonian of the E(5)-β2n model is proposed.     

核素稳定区外围线的汇合

在氘氚结团核素图中,稳定区局部区域以质子数Z=18,38,58与幻数中子数N=20,50,82为界,稳定区边界折线延伸会合于坐标S轴与坐标H=30与S=30的坐标,(22,30)(24,30)及(30,16)^(30,0).范围常数44在稳定区外围的坐标(44,44)(44,22)(22,22)(22,0)显示出来.因为在氘氚结团中可能屏蔽了核子间复杂相互作用的主要部分,故能发现核素体系深层本质规律.     

A Low-Temperature Broadband NMR Probe for Multinuclear Cross-Polarization

Dissolution dynamic nuclear polarization (D-DNP) probes are usually designed for one or at most two specific nuclei. Investigation of multiple nuclei usually requires manufacturing a number of costly probes. In addition, changing the probe is a time-consuming process since a system that works at low temperature (usually between 1.2 and 4.2 K) must be warmed up, thus increasing the risks of contamination. Here, an efficient apparatus is described for D-DNP designed not only for microwave-enhanced direct observation of a wide range of nuclei S such as ¹H, ¹³C, ²H, ²³Na, and ¹⁷O, but also for cross-polarization (CP) from I=¹H to such S nuclei. Unlike most conventional designs, the tuning and matching circuits are partly immersed in superfluid helium at temperatures down to 1.2 K. Intense radio-frequency (RF) fields with amplitudes on the order of 50 kHz or better can be applied simultaneously to both nuclei I and S using RF amplifiers with powers on the order of 90 and 80 W, respectively, without significant losses of liquid helium. The system can operate at temperatures over a wide range between 1.2 and 300 K.     

Observation of nuclear track in organic material by Atomic Force microscopy in real time during etching

The developments of Atomic Force Microscopy (AFM) allow to investigated solid surfaces with a nanometer scale. These techniques are useful methods allowing direct observation of surface morphologies. Particularly in the nuclear track fields, they offer a new tool to give many new informations on track formation. In this paper we present the preliminary results of a new use of this technique to characterize continuously the formation of the revealed track in a cellulose nitrate detector (LR115) after an alpha particle irradiation. For that, a specific cell has been used to observe, by nano-observations, the evolution of track shapes simultaneously with chemical treatment. Thus, the track shape evolution has been studied; visualizing the evolution of the tracks in real time, in situ during the chemical etching process.     

A Theoretical and Experimental Study of the Interaction of C6F6 with Electron Donors

The NMR effects produced on the nitrogen absolute shieldings in a series of electron donors when they interact with hexafluorobenzene, C₆F₆, have been theoretically studied. The complexes have been optimized at the B3LYP/6-311++G** level and the NMR shieldings have been calculated using the GIAO method. The results obtained have allowed devising an experiment (C₆F₆···NCCH₃ complex) that is compatible with the theoretical calculations.     

Experimental aspect of solid-state nuclear magnetic resonance studies of biomaterials such as bones

Solid-state nuclear magnetic resonance (SSNMR) spectroscopy is increasingly becoming a popular technique to probe micro-structural details of biomaterial such as bone with pico-meter resolution. Due to high-resolution structural details probed by SSNMR methods, handling of bone samples and experimental protocol are very crucial aspects of study. We present here first report of the effect of various experimental protocols and handling methods of bone samples on measured SSNMR parameters. Various popular SSNMR experiments were performed on intact cortical bone sample collected from fresh animal, immediately after removal from animal systems, and results were compared with bone samples preserved in different conditions. We find that the best experimental conditions for SSNMR parameters of bones correspond to preservation at −20 °C and in 70% ethanol solution. Various other SSNMR parameters were compared corresponding to different experimental conditions. Our study has helped in finding best experimental protocol for SSNMR studies of bone. This study will be of further help in the application of SSNMR studies on large bone disease related animal model systems for statistically significant results.     

Ground State Structure of Hs Super-heavy Isotopes

The ground state properties of Hs nuclei studied in the framework of the relativistic mean field theory revealed that more stable isotopes are located on the proton abundant side of the chain.The last stable nucleus to the proton drip line is ~(256)Hs.The most stable unknown Hs nucleus may be ~(268)Hs.The density dependent delta interaction pairing is used to improve the BCS pairing correction,which results in more reasonable single-particle energy level distributions and nucleon occupation,and it is shown to be available to describe the properties of nuclei in the superheavy region.