Sorption of methane,ethane, propane,butane, carbon dioxide,and nitrogen on kerogen

Sorption isotherms of nitrogen, methane (in the pressure range of 0.1–40 MPa), ethane (0.1–3.7MPa), propane (0.01–1 MPa), butane (0.01–0.2 MPa), and carbon dioxide (0.1–6 MPa) are measured on two adsorbents with kerogen contents of 16 and 75% at temperatures of 303, 323, 343 K. Adsorption volumes are calculated for all adsorption systems using two independent methods. The BET technique is used to determine the surface area values of the two adsorbents on the basis of sorption data for ethane, propane, butane, and carbon dioxide. The initial and isosteric adheat of sorption values are calculated on the basis of sorption isotherms of ethane, propane, butane, carbon dioxide measured at three temperatures. It is found from comparing the dependences of isosteric heat of sorption on the two adsorbents that molecules of the above gases diffuse into its bulk (adsorbent 2) in addition to sorbing on the outside surface formed by kerogen molecules, while sorption of the same gases on the rock (adsorbent 1) is similar to sorption on a smooth hard adsorbent surface.     

Behaviour of Mo,Al, As,Cs, Sn,Sb, Pd,Rh, Ru,Ge, Se and Te on the macroporous resin AG MP-1 in alkaline medium

The behaviour of Mo and some other elements on Ag MP-1 in alkaline medium was investigated. Equilibrium distribution coefficients, K_d, are presented for Mo on the anion exchangers AG 1-X2, AG 1-X4, AG 1-X8 and AG MP-1, and for some elements on AG MP-1 in alkaline medium. An anion exchange chromatographic separation of Mo from some of these elements is described and some results obtained with this method are reported.     

Theoretical Study on the Structure and Stability of Si5X （X = Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl） Clusters

1 INTRODUCTION In the later 60s of last century, silicon substituted for germanium to present as mainstream in semicon- ductor. The semi-conductive devices made by silicon have many advantages, for example, refractory pro- perty, high radioresistance, simple and stable process- ing technic, high machinability and low cost. So it was widely used to manufacture large power appara- tuses, for instance, digit and linear integrated circuit, large scale integrated circuit (LSI), etc. Thus, th…     

Magnetic nanoparticles: Synthesis, stabilization, functionalization, characterization, and applications

This review focuses on the synthesis, protection, functionalization, characterization and with some applications of magnetic nanoparticles (MNPs). The review begins with an overview on magnetic property and single domain particles. The synthetic strategies developed for the generation of MNPs, with a focus on particle formation mechanism and recent modifications made on the synthesis of monodisperse samples of relatively large quantities are also discussed. Then, different methodologies for the protection and functionalization of the synthesized MNPs, together with the characterization techniques are explained. Finally, some of the recent industrial, biological, environmental and analyticals application of MNPs are briefly reviewed, and some future trends and perspectives in these research areas will be outlined.     

First-principles Density Functional Theory Elucidation of the Hydrogen Evolution Reaction on TM-promoted TiC2 (TM=Fe,Co, Ni,Cu, Ru,Rh, Pd,Ag, Os,Ir, Pt,and Au)

Single-atom-catalyst-based systems have been attractive by virtue of their desirable catalytic performance. Herein, the possibility of the 15 transition-metal (TM)-promoted (TM=Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Ag, Cd, Os, Ir, Pt, Au, and Hg) and their hydrogen evolution reaction (HER) performance were investigated on two-dimensional titanium carbides (TiC₂). It is found that the adsorption strength of TMs on TiC₂ is stronger than that of TMs on γ-graphyne and weaker than that of TMs on Ti₃C₂. Among the fifteen investigated catalysts, Ru−TiC₂, Ag−TiC₂, Ir−TiC₂, Au−TiC₂, and Fe−TiC₂ exhibits overpotential of −0.18, −0.15, −0.18, −0.17, and −0.04 V, respectively. In addition, the Volmer-Tafel step was preferred to the Volmer-Heyrovsky step on Fe−TiC₂. This work suggests that Fe−TiC₂ is possibly a superior HER electrocatalyst.     

Catalysis in the Synthesis of S,N-Heterocycles and O,N-, S,N-, and O,S,N-Macroheterocycles

The review systemizes and generalizes published data on the catalytic syntheses of six-, seven-, and eight-membered S,N-heterocycles and O,N-, S,N-, and O,S,N-macroheterocycles.     

Polarization consistent basis sets. 4: the elements He, Li, Be, B, Ne, Na, Mg, Al, and Ar

Polarization consistent basis sets, optimized for density functional calculations, are proposed for the elements He, Li, Be, B, Ne, Na, Mg, Al, and Ar. The basis sets for He, B, Ne, Al, and Ar are assigned based on the previously proposed basis sets for H, C-F, and Si-Ar. The basis sets for Li, Be, Na, and Mg are defined based on energetic analysis along the lines used in previous work and the performance for molecular systems. The performance for atomization energies is comparable to those for systems composed of the elements H, C-F, and Si-Ar.     

Electrothermal atomic absorption determination of arsenic, antimony, bismuth, manganese, nickel, selenium, tellurium, and chromium in pure copper

Summary Traces of As, Bi, Cr, Mn, Ni, Sb, Se and Te in pure copper were determined by means of electrothermal atomic absorption spectrometry using continuum source background correction and computer signal processing. The effect of the copper matrix on the atomic absorption signals close to the noise level and on sensitivity are studied. The limits of detection were determined in the presence of 50 g of copper.

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Elektrothermische Atomabsorptionsbestimmung von Spuren Arsen, Antimon, Bismut, Mangan, Nickel, Selen, Tellur und Chrom in reinem Kupfer

     

Polarization consistent basis sets. VII. The elements K, Ca, Ga, Ge, As, Se, Br, and Kr

Polarization consistent basis sets, optimized for density functional calculations, are proposed for the elements K, Ca, Ga, Ge, As, Se, Br, and Kr. The basis set composition in terms of number of primitive functions and the contraction is defined based on energetic analyses of atoms and molecules along the lines used in previous work and on the performance for molecular systems. The performance for atomization energies and dipole moments is compared to other widely used basis sets, and it is shown that the new basis sets allow a systematic reduction of basis set errors and in general perform better than existing ones.     

Hydration forces: Observations, explanations, expectations, questions

The hydration force between large molecules or large surfaces is built on weak perturbation of many solvent molecules. The structure of the surface sets boundary conditions on solvent while structural forces within the solvent set the range. For this collection of essays, we focused on forces between surfaces at nanometer separations. It is instructive to distinguish primary hydration, the binding of water and perturbation within a few layers, from secondary hydration related to redistribution of solutes. The subject is still basically empirical, lacking satisfactory theory and sufficient measurement.     

The geometric, electronic, and magnetic properties of Ag5X+ (X = Sc, Ti, V, Cr, Mn, Fe, Co, and Ni) clusters

Density functional theory calculations are performed on small cationic transition metal doped silver clusters, Ag5X+ (X = Sc, Ti, V, Cr, Mn, Fe, Co, and Ni) using the B3LYP and BP86 functionals. Several two-dimensional and three-dimensional isomers with the dopant at a high coordinated site are found to be close in energy. The relative energy of the isomers is checked with CCSD(T). The interaction between the dopant 3d electrons and the host is discussed by considering the density of states and the shape of the molecular orbitals. A large local spin magnetic moment on the dopant atom is predicted.     

Reduction specifics of rare-earth orthovanadates (REE = La,Nd, Sm,Dy, Ho,Er, Tm,Yb, and Lu)

The reduction specifics of REE orthovanadates LnVO₄ (Ln = La, Nd, Sm, Dy, Ho, Er, Tm, Yb, and Lu) have been studied using the temperature-programmed reduction (TPR) method. Hydrogen and carbon monoxide were chosen as reducing agents. The reduction temperature is found to depend both on the REE and the reducing agent. REE orthovanadates are reduced in the range 1033–1153 K not forming phases that contain vanadium in intermediate oxidation states. In CO, the reduction temperature is found to be higher than in H₂ for all orthovanadates. TPR data have been used to calculate the activation energies of reduction of REE orthovanadates using the Kissinger equation. The effective activation energies of reduction depend on the REE and the reducing agent and are in the range 41–147 kJ/mol.     

Muscarine,imidazole, oxazole,thiazole, Amaryllidaceae and Sceletium alkaloids

A review with 136 references covers the literature from July 2000 to June 2001 on the isolation, bioactivities, and synthetic highlights of complex natural products including muscarine, imidazole, oxazole, thiazole, Amaryllidaceae and Sceletium alkaloids.     

Seven germacranolides,eupaglehnins A,B, C,D, E,and F,and 2alpha-acetoxyepitulipinolide from Eupatorium glehni

Four new germacrane-type sesquiterpenoids with unsaturated acids as esters at the 8-position, two chlorine atom-containing lactones, 2alpha-acetoxyepitulipinolide, and 12 previously known compounds have been isolated from the MeOH extract of Eupatorium glehni (Compositae) and their structures have been determined on the basis of spectral data analyses.     

Sorption of butane, propane, ethane, methane, and carbon dioxide on asphaltene

Isotherms of sorption of butane, propane, ethane, methane, and carbon dioxide on an asphaltene sample of known elemental composition were measured. The effect of the pressure and temperature on the shape the sorption isotherms for all the adsorption systems studied was examined. The values of the initial heat of sorption were determined and compared to the energies of interaction of the molecules with asphaltene. The results obtained suggest that asphaltene is a swellable amorphous sorbent.     

电感耦合等离子体质谱法(ICP-MS)测定稀土矿中钇、镧、铈、镨、钕、钐、铕、钆、铽、镝、钬、铒、铥、镱、镥和钪量

通过用四酸与微波消解法溶解样品对比,建立了用硝酸、盐酸、氢氟酸、高氯酸分解样品,采用电感耦合等离子体质谱法(ICP-MS)测定稀土矿中16种元素含量。方法采用_¹⁰³Rh作为内标消除干扰,确定了最优测定条件,16种稀土元素检出限为0.0029-0.0099ng/mL,测定范围为0.0005-0.020%。精密度试验、加标回收试验及标准物质检测,结果验证了方法的可行性及准确性。该方法简单易操作,结果可靠,能满足实验分析要求。     

Pi bonding and negative hyperconjugation in mono-, di-, and triaminoborane, -alane, -gallane, and -indane

A systematic quantum chemical investigation of mono-, di-, and triaminoborane, -alane, -gallane, and -indane is carried out to determine quantitatively the effects of pi bonding and negative hyperconjugation on structures, energetics, and rotational barriers in these systems. Pi bonding plays a significant role in the aminoborane compounds, but becomes rapidly less significant in the aminoalanes, -gallanes, and -indanes. For each main-group metal X investigated, X-N rotational barriers are found to be essentially equal depending only on the number of remaining in-plane amino groups. The contribution of negative hyperconjugation to reducing rotational barriers, as assessed from natural bond orbital (NBO) delocalization energies, is independent of the pyramidalization of the out-of-plane amino group, and is also dependent only on the number of rotated groups. Optimized tris[bis(trimethylsilyl)amino]-substituted structures of boron, aluminum, gallium, and indium are found to compare quite well with available experimental structural data, and exhibit X-N torsion angles that are independent of the central metal atom.     

Formation,structure, composition,and catalytic properties of Ni-, Cu-, Mn-, Fe-, and co-containing films on aluminum

Layers containing oxygen compounds of copper and nickel and(or) of one of transition metals (manganese, cobalt, iron) were formed on an aluminum alloy by the plasma-electrolytic oxidation method. The layers were characterized by means of X-ray phase analysis, X-ray fluorescence microanalysis, and scanning electron microscopy and tested in the reaction of CO oxidation to CO₂.     

Comparison of partial digestion procedures for determination of Ca, Cr, Cu, Fe, K, Mg, Mn, Na, P, and Zn in milk by inductively coupled plasma-optical emission spectrometry

A fast procedure was developed for determination of Ca, Cr, Cu, Fe, K, Mg, Mn, Na, P, and Zn in milk samples. This procedure consisted of a partial digestion with hydrochloric acid on a hot plate. The results obtained were compared with 3 other digestion procedures (dry ashing and 2 microwave digestions). All the procedures showed similar precision levels, with coefficients of variation <10% for most analyzed elements. Accuracy was evaluated by using certified reference materials, and the values obtained were within the confidence intervals for these products. The results obtained were not considered statistically different. The partial digestion on a hot plate with HCl can be very practical for laboratories with relatively large numbers of sample analyses.     

Structure and electronic properties of PbnM (M=C, Al, In, Mg, Sr, Ba, and Pb; n=8, 10, 12, and 14) clusters: theoretical investigations based on first principles calculations

A systematic theoretical study of the PbnM (M=C, Al, In, Mg, Sr, Ba, and Pb; n=8, 10, 12, and 14) clusters have been investigated to explore the effect of impurity atoms on the structure and electronic properties of lead clusters. The calculations were carried out using the density functional theory with generalized gradient approximation for exchange-correlation potential. Extensive search based on large numbers of initial configurations has been carried out to locate the stable isomers of PbnM clusters. The results revealed that the location of the impurity atom depends on the nature of interaction between the impurity atom and the host cluster and the size of the impurity atom. Whereas, the impurity atoms smaller than Pb favor to occupy the endohedral position, the larger atoms form exohedral capping of the host cluster. The stability of these clusters has been analyzed based on the average binding energy, interaction energy of the impurity atoms, and the energy gap between the highest occupied and lowest unoccupied energy levels (HLG). Based on the energetics, it is found that p-p interaction dominates over the s-p interaction and smaller size atoms interact more strongly. The stability analysis of these clusters suggests that, while the substitution of Pb by C or Al enhances the stability of the Pbn clusters, Mg lowers the stability. Further investigations of the stability of PbnM clusters reveal that the interplay between the atomic and electronic structure is crucial to understand the stability of these clusters. The energy gap analysis reveals that, while the substitution of Mg atom widens the HLG, all other elements reduce the gap of the PbnM clusters.