Development of a dispersive liquid-liquid microextraction method based on solidification of a floating organic drop for the determination of beta-carotene in human serum

A dispersive liquid-liquid microextraction method based on solidification of a floating organic drop (DLLME-SFO) was developed for HPLC determination of β-carotene in human serum. A narrow-neck glass tube was used for simple and rapid collection of the solidified organic phase from aqueous surface after its centrifugation and cooling in a water bath. Acetone and 2-decanol were used as the disperser and organic phases, respectively. Effects of salt concentration and phase volumes on the extraction of the analyte were optimized using a central composite design method. During the optimization, a spectrophotometric method was used for determinations. Under the optimized conditions, an extraction recovery of 99.0 ± 2.4% was obtained for five replicated analyses of β-carotene with an enrichment factor of 40. A detection limit of 0.08 μg/mL was achieved. The proposed method was successfully applied to the determination of β-carotene in human serum samples.     

Chemical Bonding Tuned Lattice Anharmonicity Leads to a High Thermoelectric Performance in Cubic AgSnSbTe3

Comprehension of chemical bonding and its intertwined relation with charge carriers and heat propagation through a crystal lattice is imperative to design compounds for thermoelectric energy conversion. Here, we report the synthesis of large single crystal of new p-type cubic AgSnSbTe₃ which shows an innately ultra-low lattice thermal conductivity (κ_lat) of 0.47–0.27 Wm⁻¹ K⁻¹ and a high electrical conductivity (1238 – 800 S cm⁻¹) in the temperature range 294–723 K. We investigated the origin of the low κ_lat by analysing the nature of the chemical bonding and its crystal structure. The interaction between Sn(5 s)/Ag(4d) and Te(5p) orbitals was found to generate antibonding states just below the Fermi level in the electronic band structure, resulting in a softening of the lattice in AgSnSbTe₃. Furthermore, the compound exhibits metavalent bonding which provides highly polarizable bonds with a strong lattice anharmonicity while maintaining the superior electrical conductivity. The electronic band structure exhibits nearly degenerate valence-band maxima that help to achieve a high Seebeck coefficient throughout the measured temperature range and, as a result, the maximum thermoelectric figure of merit reaches to ≈1.2 at 661 K in pristine single crystal of AgSnSbTe₃.     

Degradation of methylene blue via Co–TiO<Subscript>2</Subscript> nano powders modified by meso-tetra(carboxyphenyl)porphyrin

TiO₂ photocatalylysts as an environmental cleaning factor has drawn considerable attention due to the global increase in the level of environmental pollutions. Studies on the development of new TiO₂ materials wherein its photocatalytic activity can be activated by visible light will be valuable for field application. In this study, porphyrins/Co-doped TiO₂ were prepared by sol–gel method. The nanopowders were characterized by means of X-ray diffraction, energy dispersive X-ray spectroscopy, IR spectroscopy and transmission electron microscopy (SEM). In addition, the photocatalytic degrading efficiency of porphyrins/Co-doped TiO₂ complexes on the methylene blue decomposition under irradiation with visible light is evaluated.     

Solving a class of two-dimensional linear and nonlinear Volterra integral equations by the differential transform method

In this paper, we will give some results for developing the two-dimensional differential transform (TDDT) for double integrals. Then the TDDT method will be developed for solving a class of two-dimensional linear and nonlinear Volterra integral equations. We also give some examples to demonstrate the accuracy of the method.     

Iterative In Situ Click Chemistry Creates Antibody‐like Protein‐Capture Agents

Special agents for protein capture : Iterative in situ click chemistry (see scheme for the tertiary ligand screen) and the one‐bead–one‐compound method for the creation of a peptide library enable the fragment‐based assembly of selective high‐affinity protein‐capture agents. The resulting ligands are water‐soluble and stable chemically, biochemically, and thermally. They can be produced in gram quantities through copper(I)‐catalyzed cycloaddition.

     

Electronic and optical properties of Full-Heusler alloy Fe3?xMnxSi

The electronic and optical properties of the nonstoicheiometric Heusler alloys Fe_3−x Mn _x Si with (x = 0,0.75,1,1.25,2) have been studied by the first principles study in the framework of the density functional theory (DFT). Optical properties including the dielectric function, refractive index, energy-loss spectra, absorption spectra, optical conductivity and reflectivity were also calculated. Results show that the electronic structure of Fe_3−x Mn _x Si alloys have half-metallic property for (x = 0.75,1,1.25). The real part of dielectric function has two main peaks in high energies. From absorption spectra it can be seen that absorption curves in low energy are broadened with respect to higher energies. The refractive index has a nonlinear dispersion in the energy range of 45–55 eV. The energy of plasmon peaks obtained from electron energy loss function (ELF) are about 25 eV.     

HypoGel负载Pd纳米催化剂制备与表征及温和条件下催化Suzuki反应(英文)

A new heterogeneous catalyst composed of Pd nanoparticles immobilized within a HypoG el resin has been prepared in the absence of any ligands using an extensive cross-linking method.This newly developed nanocatalyst was characterized by N_2 adsorption-desorption,X-ray diffraction(XRD),transmission electron microscopy(TEM),scanning electron microscopy(SEM),energy dispersive X-ray(EDX),Fourier transform infrared spectroscopy and inductively coupled plasma-mass spectrometer(ICP-MS)techniques.TEM and XRD results revealed that the Pd nanoparticles were well dispersed with diameters in the range of 4–12 nm,and an average size of about 8 nm.The cross-linked Pd catalyst demonstrated excellent catalytic activity towards the synthesis of a series of biaryl compounds by the reaction of various aryl halides(e.g.,bromides andiodides)with phenylboronic acid in the presence of tetrabutylammonium bromide.ICP-MS analysis indicated that there was only 0.25%weight loss of Pd(0.55±0.02 ppm)from the supported catalyst after the first cycle reaction.Furthermore,the catalyst showed excellent reusability(up to five uses)with consistently high levels of catalytic activity following its recovery by filtration.     

Impacts of external electric fields on the permeation of glycerol and water molecules through aquaglyceroporin-7: molecular dynamics simulation approach

The European Physical Journal E - The current research numerically investigates the Marangoni convection in a cylindrical annulus filled with hybrid nanofluid saturated porous media. The interior...