Factors Controlling the Distribution of Transitional Metal Elements in Marine Hydrogenic Ferromanganese Crusts

A series of selective dissolution experunents were conducted on the hydrogeinc ferromanganese crusts collected near Line Island to study the geochemistry of Mn, Fe, Cu, Co, Ni and Ti. Despite of the fact that the very close intergrowth between amorphous ferric oxyhydroxides and 6-MnO2 exists in the hydrogenic ferromanganese crusts, there is no isomorphous substitution between iron and manganese. This is because the two elements in oxides have different crystal chemistry and geochemistry, such assertion bemg in agreement with the results of selective dissolution experiments. Transitional metal elements such as Cu, Co, Ni and Ti are enriched in different phases, i.e. Ni and Co are incorporated into 6-MnO2 while Cu and Ti are incorporated into ferric oxyhy- droxides. The distributions of the elements in amorphous ferric oxyhydroxides and δ-MnO2 are controlled by the existing states of the elements in the seawater and the crystal chemistry and geochemistry of these elements/inns in oxides.

Finite element analysis of elasto-plastic plate bending problems using transition rectangular plate elements

In this work, the finite element analysis of the elasto-plastic plate bending problems is carried out using transition rectangular plate elements. The shape functions of the transition plate elements are derived based on a practical rule. The transition plate elements are all quadrilateral and can be used to obtain efficient finite element models using minimum number of elements. The mesh convergence rates of the models including the transition elements are compared with the regular element models. To verify the developed elements, simple tests are demonstrated and various elasto-plastic problems are solved. Their results are compared with ANSYS results.

Infrared emissivity of transition elements doped ZnO

Infrared emissivity was studied in Zno.99Mo.olO （M is Mn, Fe or Ni） and Znl_xCoxO （x=0.01, 0.02, 0.03 and 0.04） powders synthesized by solid-state reaction at various temperatures. XRD patterns confirm the wurtzite structure of the prepared samples. No peaks of other phases arising from impurities are detected in Mn- and Co-doped ZnO, hut the peaks of ZnFe204 and NiO are observed in Zno.99Feo.010 and Zno.99Nio.o10. The SEM observations indicate that with larger grain sizes than those of Zn0.99Feo.010 and Zno.99Ni0.010, Co-doped ZnO exhibits smooth grain surfaces. The infrared absorption spectra show that infrared absorptions related to oxygen in Zn0.99M0.010 are much stronger than those in Co-doped ZnO. Co ions are dissolved into the ZnO lattice with Co2＋ state from XPS spectra analysis. The infrared emissivity results imply that the emissivity of Zno.99Ni0.010 is the highest （0.829） and that of Zno.99C00.010 is the lowest （0.784） at 1 200 ℃. The emissivity of Zno.99Co0.010 decreases to the minimum （0.752） at 1 150 ℃ and then increases with growing calcination temperature. As the Co doping content grows, the emissivity of Co-doped ZnO calcined at 1 200 ℃ falls to 0.758 in the molar fraction of 3% and then ascends.

Influence of Substitution of Transition Elements for Fe on the Structure and Magnetic Properties of the Nd_(16)Fe_(75)AI_2B_7 AHoy

1.IntroductionThe influence of substitution of variouselements for Fe on the magnetic propertiesof the NdFeBalloy has been investi-gated by several authors,among which theAl substitution can increase the coercivity[1]and the addition of both Co and Al has beenproved to have a positive effect on im-proving both the coercivity and other per-

A GROUP OF ISOPARAMETRIC ELEMENTS SUITABLE FOR ST．VENANT’S TORSION OF A BAR WITH CRACKS

In this paper, we shall give a group of new isoparametric elements suitable .for St.Wnant's torsion of a bar with vertical cracks. These elements are eight-pointisoparametric element, quarter eight-Point isoparametric element and eight-pointisoparametric transition element. Among these elements, the second and the thirdelements possess the singularity of order r-1/2 at crack tip. Using these elements, wehave completed the calculations of St. Venant's torsion for a cylinder with a radialvertical crack. The calculated results show that the isoparametric elements given bythis paper have ideal accuracy. good convergence. high speed of convergence, lowfreedom and little computational time, and so they can be widely applied to practice.

Definition and Application of Topological Index Based on Bond Connectivity

Bond connectivity topological index S i based on chemical bonds was defined by using a matrix method.And S i is formed by atomic parameters such as the number of valence electrons,the number of the highest main quantum of atoms and the bonding electrons and bond parameters such as the length of bonds,the electronegativity difference of bonding atoms.The molecular bond connectivity topological index S is composed of S i.The thermodynamic properties of saturated hydrocarbons,unsaturated hydrocarbons,oxygen organic,methane halide and transitional element compounds and the molecular bond connectivity topological index S have an optimal correlative relationship.

Photo-Controlled MOBILE's

A novel optoelectronic functional circuit with heterojunction phototransistors (HPTs) and resonant tunneling diodes (RTDs) is described,which presents the function of both photocurrent switching and photo-current latching.These behaviors have been demonstrated by simulating experiments and circuit simulation.Furthermore,basing on photo-current latching behavior,various photo-controlled basis logic elements such as delayed flip-flop (DFF) can be designed and fabricated.

A Fundamental DFT Study of Anatase(TiO2) Doped with 3d Transition Metals for High Photocatalytic Activities

Anatase（TiO_2） has been widely used in photocatalysis. However, it can only absorb near-ultraviolet light with a wavelength below approximately 388 nm due to a wide band gap. Therefore a modification should be made for anatase to increase its capability in utilizing more abundant visible light. We investigated the doped anatase with the most promising 3d transition metal elements, and the results showed that the visible light absorption intensity was increased significantly due to the reduced band gap and the cavitation effects. As compared to other 3d transition metals, Cu was found to be the most effective one in improving anatase photocatalytic effects. In addition, greater Cu concentration doped in the anatase increased the photocatalysis effects but reduced the anatase stability, therefore, an optimized Cu concentration should be considered to optimize the anatase photocatalysis activity.

Geochemical anomaly and the causes of transition metal accumulations in late Permian coal from the eastern Yunnan-western Guizhou region

The concentration of 39 trace elements in coal from the late Permian taken from the eastern Yunnan-western Guizhou region was determined using inductively coupled plasma mass spectrometry. It was found that the mean content of Ti, V, Cr, Mo, Co, Ni, Y, and Zr is higher than the national average. The occurrence of Mn, Ni, and Co in the different coalfields is distinctly different. Most of the enriched transition metal elements exist mainly as inorganic minerals. In the Zhina coalfield, Co, Ni, and Nb are primarily associated with sulfur. Mn, Cs, and Mo are mostly sulfides. Almost all Co was organic and a significant part of the Ni is also organic in the Liupanshui coalfield. Cs, Co, and Ni are related to sulfur in the coal taken from eastern Yunnan. Carbonate is the main form of Mn in the coal from eastern Yunnan and the Liupanshui coalfield. Ti is the oxide in the coal samples where Ti is enriched. Zr is in the form of zircon in the samples where Zr is enriched. The situation for most of the transition metal elements is consistent with terrestrial genesis. Coal seams are universally influenced by the sea. The strongly seawater effected peat bog with a reductive and alkaline environment favors the relative enrichment of Mn. A reducing environment is conducive to transition metal element enrichment.

The partitioning behavior of trace elements in subduction zones:Advances and prospects

The partitioning behavior of trace elements is of key importance for understanding the geochemical process and material cycle mechanism in subduction zones.This paper focuses on the advances and prospects on the studies of trace element partitioning in subduction zones from the following four aspects.(1)The properties of fluids derived from subducting slabs and their ability in element transport.How slab-derived solute-rich fluids and supercritical fluids are formed and what the roles and key control factors of these fluids are in transferring of elements(especially the high field strength elements)from slab to wedge are discussed.We point out that the detailed investigations of supercritical fluids may provide a new perspective for the element migration mechanism,material cycle process,arc magma genesis and so on.(2)The behavior of transition elements during mantle wedge melting.The behavior of the first row transition elements(Sc,Ti,V,Cr,Mn,Fe,Co,Ni,Cu,Zn)in the mantle partial melting process is compatible or incompatible,depending on residual mineral assemblage and physicochemical conditions.The partitioning behavior of the elements such as Sc,Ti,Co,Ni and Zn whose valence states do not change in the melting process mainly depends on the residual mineral assemblage and temperature,whereas the partitioning behavior of the multivalent elements such as V and Fe is also the function of oxygen fugacity(fO_(2))in addition to mineral assemblage and temperature.Therefore,the partitioning behavior of transition elements has important applications in tracing lithologic inhomogeneity and fO_(2)of the mantle wedges.(3)The specificity of element partitioning behavior during arc magma evolution.Garnet has Dy/Yb partitioning behavior different from amphibole,and rutile has Nb/Ta partitioning behavior different from amphibole.Dy/Yb and Nb/Ta partitioning differences for these minerals enable to distinguish the specific evolution process of arc magmas.The Dy/Yb and Nb/Ta generally decrease with the increase of SiO_(2)in arc magmas,indicating that amphibole fractionation should be the most important during arc magma differentiation.(4)The behavior of sulfur and chalcophile elements and porphyry metallogeny.In subduction zones,the behavior of chalcophile elements such as Cu and Au is controlled by sulfide and fluid.Therefore,the stability of sulfide,the time at which the fluid exsolves from the melt relative to sulfide saturation,the fluid/sulfide mass ratio and fluid/melt Cu and Au partition coefficients in intermediate-felsic magma-H_(2)O systems are especially important in understanding Cu and Au enrichment in magma-hydrothermal processes.Intermediate-felsic magmas mainly originate from the differentiation of arc magmas at lower crustal reservoirs,and thus the fluid exsolution from the lower crustal reservoirs and the fluid/melt and fluid/sulfide partition coefficients of Cu and Au should be the keys to understanding quantitatively how Cu and Au are migrated from the deep crust to the shallow site of mineralization.

AN ADAPTIVE HYBRID STRESS TRANSITION QUADRILATERAL FINITE ELEMENT METHOD FOR LINEAR ELASTICITY

In this paper, we discuss an adaptive hybrid stress finite element method on quadri- lateral meshes for linear elasticity problems. To deal with hanging nodes arising in the adaptive mesh refinement, we propose new transition types of hybrid stress quadrilateral elements with 5 to 7 nodes. In particular, we derive a priori error estimation for the 5- node transition hybrid stress element to show that it is free from Poisson-locking, in the sense that the error bound in the a priori estimate is independent of the Lam~ constant A. We introduce~ for quadrilateral meshes, refinement/coarsening algorithms, which do not require storing the refinement tree explicitly, and give an adaptive algorithm. Finally, we provide some numerical results.

A Modified Nonconforming 5-Node Quadrilateral Transition Finite Element

This paper analyzes a nonconforming 5-node quadrilateral transition finite element for Poisson equation.This element was originally proposed by Choi and Park[Computers and Structures,32(1989),pp.295–304 and Thin-Walled Structures,28(1997),pp.1–20]for the analysis of Mindlin plates.We show the consistency error of this element is only O(h^(1/2))over the transition edges of the quadrilateral subdivision.By modifying the shape functions with respect to mid-nodes,we get an improved version of the element for which the consistency error is O(h).Numerical examples are provided to verify the theoretical results.

A flexible logic circuit based on a MOS-NDR transistor in standard CMOS technology

A MOS-NDR（negative differential resistance） transistor which is composed of four n-channel metaloxide -semiconductor field effect transistors（nMOSFETs） is fabricated in standard 0.35μm CMOS technology.This device exhibits NDR similar to conventional NDR devices such as the compound material based RTD（resonant tunneling diode） in current-voltage characteristics.At the same time it can realize a modulation effect by the third terminal. Based on the MOS-NDR transistor,a flexible logic circuit is realized in this work,which can transfer from the NAND gate to the NOR gate by suitably changing the threshold voltage of the MOS-NDR transistor.It turns out that MOS-NDR based circuits have the advantages of improved circuit compaction and reduced process complexity due to using the standard IC design and fabrication procedure.

Group Theory Approach for the Stimulated Raman Scattering in Fiber

The symmetry of rotation vibration spectra of molecule SiO_2 is described by means of group U(5). Grouptheory approach is adopted to give the matrix elements of stimulated Raman scattering in fiber. The cross sectionsand gain coefficients of stimulated Raman scattering are given. The results are in good agreement with the experi-mental values.