One-step synthesis of magnetic composite UiO-66/Fe3O4/GO for the removal of radioactive cesium ions

Journal of Radioanalytical and Nuclear Chemistry - In this study, the UiO-66/Fe3O4/GO composite was prepared by one step method for removal of cesium ions (Cs+) in water and exhibited excellent...     

Countable Products of Čech-scattered supercomplete spaces

We prove by using well-founded trees that a countable product of supercomplete spaces, scattered with respect to ech-complete subsets, is supercomplete. This result extends results given in [1], [5], [6], [19], [26] and its proof improves that given in [19].     

Perfect 3-colorings on 6-regular graphs of order 9

The concept of a perfect coloring, introduced by P. Delsarte, generalizes the concept of completely regular code. We study the perfect 3-colorings (also known as the equitable partitions into three parts) on 6-regular graphs of order 9. A perfect n-colorings of a graph is a partition of its vertex set. It splits vertices into n parts A1, A2,...,An such that for all i,j∈{1,2,...,n}, each vertex of Ai is adjacent to aij vertices of Aj. The matrix A =(aij)n×n is called quotient matrix or parameter matrix. In this article, we start by giving an algorithm to find all different types of 6-regular graphs of order 9. Then, we classify all the realizable parameter matrices of perfect 3-colorings on 6-regular graphs of order 9.     

Small molecule‐mediated control of hydroxyapatite growth: Free energy calculations benchmarked to density functional theory

The unique, plate‐like morphology of hydroxyapatite (HAP) nanocrystals in bone lends to the hierarchical structure and functions of bone. Proteins enriched in phosphoserine (Ser‐OPO₃) and glutamic acid (Glu) residues have been proposed to regulate crystal morphology; however, the atomic‐level mechanisms remain unclear. Previous molecular dynamics studies addressing biomineralization have used force fields with limited benchmarking, especially at the water/mineral interface, and often limited sampling for the binding free energy profile. Here, we use the umbrella sampling/weighted histogram analysis method to obtain the adsorption free energy of Ser‐OPO₃ and Glu on HAP (100) and (001) surfaces to understand organic‐mediated crystal growth. The calculated organic‐water–mineral interfacial energies are carefully benchmarked to density functional theory calculations, with explicit inclusion of solvating water molecules around the adsorbate plus the Poisson–Boltzmann continuum model for long‐range solvation effects. Both amino acids adsorb more strongly on the HAP (100) face than the (001) face. Growth rate along the [100] direction should then be slower than in the [001] direction, resulting in plate‐like crystal morphology with greater surface area for the (100) than the (001) face, consistent with bone HAP crystal morphology. Thus, even small molecules are capable of regulating bone crystal growth by preferential adsorption in specific directions. Furthermore, Ser‐OPO₃ is a more effective growth modifier by adsorbing more strongly than Glu on the (100) face, providing one possible explanation for the energetically expensive process of phosphorylation of some proteins involved in bone biomineralization. The current results have broader implications for designing routes for biomimetic crystal synthesis. © 2013 Wiley Periodicals, Inc.     

自然循环型气液固三相流载气蒸发传热的实验研究

符号表Cs固体颗粒在液体中的含量vol．％dp固体颗粒直径mmde实验段当量直径mmh表面传热系数kw／m2Kk液体导热率W／mKq热通量kw／m2r液体汽化潜热kJ／kgTw加热壁面温度℃ug载气表现速度mm／sul循环液速m／sρg载气的密度kg／m3ρl液体的密度kg／m3ρs固体颗粒的密度kg／m3μg气相粘度mPa·sμl液相粘度mPa·sBo沸腾准数Nu努塞尔准数Reg载气雷诺数Rel液体雷诺数沸腾与蒸发装置内换热壁面上的结垢与结疤是降低换热效率的重要因素之一。换热装置的防垢抗垢一直受到重视。近年来，一些研究者将固体颗粒引入换热器的加热管内，形成流化床换热…     

Fabrication of superhydrophobic surfaces by dislocation-selective chemical etching on aluminum, copper, and zinc substrates

A surface roughening method by simple chemical etching was developed for the fabrication of superhydrophobic surfaces on three polycrystalline metals, namely aluminum, copper, and zinc. The key to the etching technique was the use of a dislocation etchant that preferentially dissolves the dislocation sites in the grains. The etched metallic surfaces, when hydrophobized with fluoroalkylsilane, exhibited superhydrophobic properties with water contact angles of larger than 150 degrees, as well as roll-off angles of less than 10 degrees for 8-microL drops. Also, the dislocation etching concept introduced here may be helpful in the fabrication of superhydrophobic surfaces on other polycrystalline substrates.     

Pure rotational spectrum and structural determination of silacyclopentane

The ground state pure rotational spectrum of silacyclopentane (SCP) has been investigated using both Fourier Transform Microwave (FTMW) and chirped pulse Fourier Transform Microwave (cp-FTMW) spectroscopies. In addition to the parent species, the spectra of the ¹³C, ²⁹Si and ³⁰Si singly-substituted isotopologues were recorded in the 6–24 GHz region in natural abundance. Structural analysis confirms that the ground state has C₂ symmetry and the geometric parameters determined based on heavy atom substitution include the bond distances, bond angles and dihedral angles of the SCP ring backbone.     

关于kr-空间与k-空间

本文给出了具有局部可数闭ｋ－网的ｋｒ－空间成为ｋ－空间的一个充要条件，此结果给林寿提出的问题作了一个回答。     

Studies on Organo-Phosphorus, -Arsenic and -Antimony Polytungstates and Polymolybdates (Ⅶ)——Preparation and Properties of p-Aminophenylarsenic Polymolybdates

In order to investigate the influence of organic groups on the types of organoarsenic polymolybdates, the reations of p-aminophenylarsonic acid with sodium molybdate were tested at pH=3-5. Six salts were prepared and characterized. (1) (CN3H8)4 [(p-NH3C6H4As)2Mo6O25] · H2O, (2) (CN3H6)4 [(p-, NH3C6H4As )2Mo6O25 ] · 6H20, (3) Cs4 [(p-NH3C6H4As)2Mo6O25] · 4H2O, (4) C(CH3)4N]4[(p-NH3C6H4As)2Mo6O25] · 5H2O, (5) [(n-C4H9)4N]3Na[(p-NH3C6H4As)2Mo6O25] · 2H2O, (6) Ba2 NH3C6H4As)2Mo6O25] · 10H2O. The IR, UV spectra, and electrochemical behavior are reported and discussed. They should belong to the same type as that for phenyl derivative or the nitrophenyl derivatives. But the ammo groups can accept protons, so that the anion' s charge decreases. Very similar to the tungsten congener (CN3H6)4[(p-NH3C,H4As)2W6O25] · 4H2O, [(RAs)2Mo6O25]4- type of complexes are formed.     

Study of the fluid flow characteristics in a porous medium for CO2 geological storage using MRI

The objective of this study was to understand fluid flow in porous media. Understanding of fluid flow process in porous media is important for the geological storage of CO₂. The high-resolution magnetic resonance imaging (MRI) technique was used to measure fluid flow in a porous medium (glass beads BZ-02). First, the permeability was obtained from velocity images. Next, CO₂–water immiscible displacement experiments using different flow rates were investigated. Three stages were obtained from the MR intensity plot. With increasing CO₂ flow rate, a relatively uniform CO₂ distribution and a uniform CO₂ front were observed. Subsequently, the final water saturation decreased. Using core analysis methods, the CO₂ velocities were obtained during the CO₂–water immiscible displacement process, which were applied to evaluate the capillary dispersion rate, viscous dominated fractional flow, and gravity flow function. The capillary dispersion rate dominated the effects of capillary, which was largest at water saturations of 0.5 and 0.6. The viscous-dominant fractional flow function varied with the saturation of water. The gravity fractional flow reached peak values at the saturation of 0.6. The gravity forces played a positive role in the downward displacements because they thus tended to stabilize the displacement process, thereby producing increased breakthrough times and correspondingly high recoveries. Finally, the relative permeability was also reconstructed. The study provides useful data regarding the transport processes in the geological storage of CO₂.