Latent heat storage performance of a layered perovskite-type compound, 1-C_(14)H_(29)NH_3)_2ZnCl_4(C_(14)Zn),embedded in a series of silica gel(SG) with pore sizes of d = 15–200 nm is investigated using differential scanning calorimetry(DSC), and powder X-ray diffractions(XRD). C_(14)Zn in the nanopores of silica gel shows size-dependent phase transition temperature, enthalpy change and supercooling. They have a stable transition temperature and heat capacity at each size in a short-term thermal cycling. Similar Xray diffraction patterns are observed for the nano-sized and the bulk C_(14)Zn. The encapsulation of a phase change material in nanopores is a new way of tuning its thermal energy storage properties for a wider range of temperature regulation. 相似文献
Sphingolipids serve not only as components of cellular membranes but also as bioactive mediators of numerous cellular functions. As the biological activities of these lipids are dependent on their structures, and due to the limitations of conventional ion activation methods employed during tandem mass spectrometry (MS/MS), there is a recognized need for the development of improved structure-specific methods for their comprehensive identification and characterization. Here, positive-ionization mode 193 nm ultraviolet photodissociation (UVPD)-MS/MS has been implemented for the detailed structural characterization of lipid species from a range of sphingolipid classes introduced to the mass spectrometer via electrospray ionization as their lithiated or protonated adducts. These include sphingosine d18:1(4E), dihydrosphingosine (sphinganine) d18:0, sphingadiene d18:2(4E,11Z), the isomeric sphingolipids ceramide d18:1(4E)/18:0 and dihydroceramide d18:0/18:1(9Z), ceramide-1-phosphate d18:1(4Z)/16:0, sphingomyelin d18:1(4E)/18:1(9Z) the glycosphingolipids galactosyl ceramide d18:1(4E)/24:1(15Z) and lactosyl ceramide d18:1(4E)/24:0, and several endogenous lipids present within a porcine brain total lipid extract. In addition to the product ions formed by higher energy collision dissociation (HCD), UVPD is shown to yield a series of novel structurally diagnostic product ions resulting from cleavage of both sphingosine carbon–carbon and acyl chain carbon–carbon double bonds for direct localization of site(s) of unsaturation, as well as via diagnostic cleavages of the sphingosine backbone and N–C amide bond linkages. With activation timescales and dissociation efficiencies similar to those found in conventional MS/MS strategies, this approach is therefore a promising new tool in the arsenal of ion activation techniques toward providing complete structural elucidation in automated, high-throughput lipid analysis workflows.
This work presents the experimental study of the isomeric ratio of 137mCe–137gCe produced in 138Ce(γ, n) 137m,gCe photonuclear reaction, in neutron capture reaction 136Ce(n, γ) 137m,gCe and in the two simultaneous reactions 138Ce(γ, n) 137m,gCe and 136Ce(n, γ) 137m,gCe in the mixed photon—neutron field by the activation method. The investigated samples were irradiated at the bremsstrahlung photon flux, in the epithermal and thermal-epithermal neutron beam and in the mixed photon-neutron field constructed at the electron accelerator Microtron MT-25 of the Flerov Laboratory of Nuclear Reaction, Joint Institute for Nuclear Research, Dubna, Russia. The results were analyzed, discussed and compared with those of other authors to examine the role of the channel effect in nuclear reaction and provide the nuclear data for theoretical model interpretation of nuclear reactions.
Di-1-methyl heptyl methyl phosphonate (DMHMP) is a promising alternative extractant for Th-U fuel reprocessing, in which the irradiation stability of extractant should be systematically studied. In this paper, the radiolysis products of DMHMP were analyzed qualitatively and quantitatively with gas and ion chromatograph, the possible radiolysis mechanism of DMHMP was also concluded. Moreover, the effect of structure on the radiolysis products and irradiation stability of neutral organophosphorus compound extractant was also discussed.
In the present study, an intracellular melanin, named LIM205, was separated from Lachnum YM205 mycelia and was purified on a Sephadex G-15 column. The molecular weight of LIM205 was determined as 522 Da, and its molecular formula was speculated as C28H14N2O7S. The possible chemical structure of LIM205 was determined according to the results of Fourier transform infrared (FT-IR), 1H NMR, 13C NMR, and pyrolysis/GC-MS analysis. With the aim to increase its water solubility, its carboxymethylated derivative, named CLIM205, was formed by the substitution of hydrogen atoms in LIM205 with one, two, and three carboxymethylate groups. FT-IR, UV, and ESI-MS analysis demonstrated that the carboxymethylate groups were conjugated onto LIM205. The lead detoxification activities of LIM205 and CLIM205 had also been investigated. In vivo test showed that both LIM205 and CLIM205 reduced the tissue lead concentration, enhanced lead excretion, and reversed lead-induced alterations in superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) concentrations in mice, with CLIM205 showed better efficacy. The study indicates that LIM205 and CLIM205 have significant lead detoxification effect which will contribute to solve related problems. 相似文献
A simple and sensitive surface-enhanced Raman spectroscopy (SERS) method for the detection of safranine T (ST) and Hg2+ using silver nanoparticles (AgNPs) as substrate was developed. ST can absorb on the surface of AgNPs through electrostatic interaction, the electromagnetic effect combined with chemical adsorption effect give a notable Raman enhancement for ST. The presence of Hg2+ well decreased the absorbed ST molecules on AgNPs, leading to a significant decrease of SERS signals thus enabling to detect Hg2+. The determination conditions for SERS, including the amount of AgNPs, the concentration of NaCl, the concentration of HCl, the concentration of ST and the reaction time, were optimised. Under the optimised experimental conditions, good linear responses were obtained for ST and Hg2+ in the concentration ranges of 0.01–4.0 μmol L?1 (3.5–1403.4 ng mL?1) and 0.01–2.0 μmol L?1 (2.0–401.2 ng mL?1), the limit of detection were 3.0 nmol L?1 (1.1 ng mL?1) and 2.0 nmol L?1 (0.4 ng mL?1), respectively. The present method was subsequently applied to the determination of ST in tomato sauces and Hg2+ in environmental waters, the recoveries of ST and Hg2+ in spiked samples are 95.5–107.8% and 91.4–110.8 %, respectively. 相似文献
TiO2 nanotubes (TNTs) were successfully synthesized from different alkaline media (i.e., NaOH and KOH) by using a microwave hydrothermal process. The effects of different alkaline media on the formation of TiO2 nanotubes and their physicochemical properties were investigated. The phases of different TiO2 nanostructures were studied by using X-ray diffraction patterns. Morphologies of the nanostructures were observed with a transmission electron microscope. The optical properties of the nanostructures were evaluated through the absorption behavior using UV–Vis diffuse reflectance spectroscopy. The photocatalytic activities of the TiO2 nanostructures were evaluated by the degradation of methylene blue aqueous dye solution under the simulated solar light irradiation. Similarly, the photovoltaic efficiencies of the prepared samples were investigated by making photo-anode layers in the Dye Sensitized Solar Cells (DSSCs). The results revealed that in comparison to the single layered TiO2 nanostructures in the DSSC, creation of a double layer structure significantly enhanced the efficiency of DSSC. 相似文献
For an arbitrary Lévy process X which is not a compound Poisson process, we are interested in its occupation times. We use a quite novel and useful approach to derive formulas for the Laplace transform of the joint distribution of X and its occupation times. Our formulas are compact, and more importantly, the forms of the formulas clearly demonstrate the essential quantities for the calculation of occupation times of X. It is believed that our results are important not only for the study of stochastic processes, but also for financial applications. 相似文献