Structure Of Na Research Articles

Dynamics and structure of nickel chloride–methanol solutions: quasi-elastic neutronscattering and molecular dynamics simulations

The high-resolution quasi-elastic neutron scattering (QENS) technique has been applied tostudy the translational diffusion of methanol protons in pure methanol (MeOH) at 223and 297 K, and in 0.3 and 1.3 molal non-aqueous electrolyte solutions (NAESs) ofNiCl2 in methanol at 297 K. Molecular dynamics (MD) simulations, in conjunction with thepresent QENS results and our previously published structural results obtained by neutrondiffraction isotopic substitution (NDIS) experiments, have been carried out in theNVT ensemble to explore the particle dynamics and microscopic structures ofthe experimentally investigated systems. The simulated structure of the∼1.35 molal NiCl2–MeOH NAES has been compared with the structures ofNi2+ andCl− coordinationshells in ∼1.4 molal NAES obtained earlier by the NDIS technique.

IDENTIFICATION AND LOCALIZATION OF NA+ K+ATPASE IN BOVINE SPERMATOZOA

Na+ K+ATPase is a ubiquitous transmembrane protein. In sperm, Na+ K+ATPase is important for fertility and capacitation, participating in ion transport and very recently shown to function as a signaling molecule in tyrosine phosphorylation. Na+ K+ATPase is a dimer, with isoforms of its alpha (1, 2, 3, and 4; approximately 110 kDa) and beta (1, 2, and 3; approximately 55 kDa) subunits. We hypothesized that specific alpha and beta isoforms in the head are more likely to be active in sperm capacitation, whereas those present in the midpiece or tail region are more likely involved in sperm flagellar activity, so this study's objective was to identify and localize subunits of Na+ K+ATPase within bull sperm. The presence and localization of Na+ K+ATPase in fresh bull sperm was identified by immunoblotting and immunocytochemistry using mouse monoclonal antibodies against the alpha 1 and 3 isoforms, and the beta 1, 2 and 3 isoforms. The relative quantity of Na+ K+ATPase present in spermatozoa HPM from different bulls was determined by densitometry of immunoblot bands and compared to ATPase in bovine kidney membranes. Sperm and kidney specifically bound all antibodies at kDa equivalent to the supplied positive control and to additional bands; the kDa of the additional bands differed between the tissues. Deglycosylation of the B1 subunit reduced the kDa of the bands in both sperm and kidney, but the mass of the deglycosylated bands still differed between kidney and sperm. All alpha and beta isoforms were detectable in bull HPM, at significantly lower concentrations than in the kidney. The most prevalent isoforms in sperm HPM were B1 (2030-4085 units/mg protein) and A3 (1650 units/mg protein), with the least being B2, where there were multiple low intensity bands; however in kidney the most abundant were A1 (402,572 units/mg protein) and B1 (136,873 units/mg protein) with multiple bands of low intensity observed in B2. The B1 isoform showed 4 bands in sperm HPM (70, 60, 40 and 45 kDa), and one band in kidney (55 kDa). Two bands were observed in HPM from the A1 isoform (105 and 100 kDa) and one band in kidney (100 kDa). Multiple bands were observed in A3, B2 and B3 for both sperm HPM and kidney, however, rat brain controls showed a single band at the appropriate molecular mass for each isoforms. Immunofluorescence of intact fresh bull sperm confirmed that all isoforms were present in the head region of spermatozoa in which HPM's were naturally disrupted or deliberately permeabilised, however completely intact cells showed no fluorescence, suggesting that the antibody binding sites are either present on the inner surface of the HPM or on the outer surface of the acrosomal membrane. The A3 subunit was also uniformly distributed postequatorially. The unique quantity, location and structure of Na+ K+ATPase in sperm suggests that this protein has unique functions in sperm. (poster)

Ionization of sodium in water clusters

Structures of Na(H2O)n and Na+(H2O)n clusters with n = 1−6, 19, and 28 are determined in the second order of the Moller-Plesset perturbation theory with the use of extended atomic basis set 6–31++G**. It is found that when the number of molecules is sufficient for the formation of two solvation shells around sodium, a continuous hydrogen-bond network is formed in both neutral and charged clusters, and the orientation of each molecule is determined by the balance between interactions with the neighboring water molecules and with the field of the central particle. In the cations, this field is stronger, and up to the third solvation shell, molecules have a predominant orientation with respect to sodium. In the neutral clusters, with an increase in the number of water molecules, the maximum of the electron density distribution of the highest occupied molecular orbital becomes more distant from the sodium nucleus, being shifted toward the cluster surface. The energy of this orbital accordingly decreases in absolute value approaching 22 kcal/mol inmicroparticles. In the charged clusters, the distribution of the positive charge generally correlates with the character of the highest occupied orbital in the neutral systems, so that with an increase in the number of molecules, the atomic charge of sodium decreases and tends to zero as n → ∞. The ionization potential of sodium changes in inverse proportion to the linear size of the cluster, and should not exceed 1.1 eV in watermicroparticles.

Itinerant in-plane magnetic fluctuations and many-body correlations inNaxCoO2

Based on the {\it ab-initio} band structure for Na$_x$CoO$_2$ we derive the single-electron energies and the effective tight-binding description for the $t_{2g}$ bands using projection procedure. Due to the presence of the next-nearest-neighbor hoppings a local minimum in the electronic dispersion close to the $\Gamma$ point of the first Brillouin zone forms. Correspondingly, in addition to a large Fermi surface an electron pocket close to the $\Gamma$ point emerges at high doping concentrations. The latter yields the new scattering channel resulting in a peak structure of the itinerant magnetic susceptibility at small momenta. This indicates dominant itinerant in-plane ferromagnetic fluctuations above certain critical concentration $x_m$, in agreement with neutron scattering data. Below $x_m$ the magnetic susceptibility shows a tendency towards the antiferromagnetic fluctuations. We further analyze the many-body effects on the electronic and magnetic excitations using various approximations applicable for different $U/t$ ratio.

In-situ synthesis of PHEMA magnetic nanogels via photochemical method

One-pot synthesis of magnetic nanogels via photochemical method is reported in this paper. Poly (2-Hydroxyethyl methacrylate) (PHEMA) magnetic nanogels are synthesized by in-situ polymerization of 2-Hydroxyethyl methacrylate (HEMA) and N, N’-methylene-bis- (acrylamide) (MBA) in Fe3O4 aqueous suspension under UV irradiation. The structure and compositions of magnetic na

Polymeric metal‐organic octupolar NLO materials: lithium(I) and sodium(I) 3,5‐dinitrobenzoates

AbstractLithium 3,5‐dinitrobenzoate (Li(dnb)) exhibits a 1D propeller chain structure of D 3 point symmetry and the chains are trigonally assembled in the crystal under the chiral space group P 3121. Sodium 3,5‐dinitrobenzoate (Na(dnb)) also crystallizes in space group P 3121 and exhibits a 3D structure. The structure of Na(dnb) could be regarded to be similar to that of Li(dnb) if the weaker Na‐O(nitro) bonds were to be ignored. These two compounds represent rare examples of octupoles arranged in an octupolar environment and show modest powder SHG effects. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Hydrothermal synthesis and crystal structure of Na(Na,Mn)7Mn22(PO4)180.5H2O, a new compound of fillowite structure type

The chemical compound Na(Na,Mn) 7 Mn 22 (PO 4 ) 18 ·0.5H 2 O was synthesized with a Tuttle pressure vessel at 800°C and 1 kbar during experimental investigations on the conditions of fillowite formation. The crystal structure of a single-crystal, space group R 3 (No. 148), a = 15.2741(9), c = 43.334(3) A, Z = 6, was determined from X-ray intensity data and refined up to R 1 = 0.0728 and R 1{FO>4σ(FO)} = 0.0546. The crystal structure of Na(Na,Mn) 7 Mn 22 (PO 4 ) 18 ·0.5H 2 O is similar to the structure of fillowite, Na 6 Ca 3 (Mn,Fe) 21 (PO 4 ) 18. , but a significant difference between the synthetic H 2 O containing compound and fillowite is the replacement of (Na12)O 8 - by Mn(H 2 O) 2 O 5 - polyhedra, which form characteristic six-member rings. The coordination polyhedra around Na12 and Mn12 are so different that simple isomorphous substitution of Na12 by Mn12 is very unlikely, but whole six-member rings either of (Na12)O 8 - or (Mn12)(H 2 O) 2 O 5 polyhedra seem to be distributed statistically over the crystal structure. No indication for ordering, e.g. sheet by sheet, has been observed. Na(Na,Mn) 7 Mn 22 (PO 4 ) 18 ·0.5H 2 O is the first fillowite-like compound for which water is located in the structure from single-crystal study. This result is proved by infrared spectral data and indicates that water can play an essential role in the fillowite structure-type. Structural features of the synthetic compounds Na(Na,Mn) 7 Mn 22 (PO 4 ) 18 ·0.5H 2 O, Na 4 Ca 4 Mg 21 (PO 4 ) 18 and fillowite are compared.

Energy and shape method for determining the valence and bond structures of crystals

Based on Xie's the one-atom self-consistency method for determining the valence and bond (VB) structures of crystal, the energy and shape (ES) method has been brought forward. New progress has been made in the theory. The VB structures are determined with the unity of lattice constant and energy minimization. To take Mg as an example, the ES method is introduced in detail. The VB structures of Na, Mg, Al, Ti, Zr and Hf are determined. The results are more refined and reliable.

Effect of FeCl3 and acetone on the structure of Na–montmorillonite studied by Mössbauer and XRD measurements

57Fe Mossbauer spectroscopy, X-ray diffraction, X-ray fluorescence spectroscopy and infrared spectroscopy were used to study the effect of FeCl3 and acetone on the structure of a Na-bentonite. XRD indicated the incorporation of Fe3+ ions into the interlayer space since the basal lattice spacing of montmorillonite increased to 1.6 from 1.24 nm after treatment with FeCl3 dissolved in acetone. Interlayer Na+ ions could be exchanged to Fe3+. Magnetically split Mossbauer subspectra with internal magnetic fields 41 and 46 T at 74 K, were associated with two main Fe3+ microenvironments within the interlayer regions. The resultant Fe-montmorillonite was successfully applied as a catalyst in the preparation of 1,1-diacetates from aromatic aldehydes and acetic acid anhydride.

U(IV)/Ln(III) mixed site in polymetallic oxalato complexes. Part III: Structure of Na[Yb(C 2O 4) 2(H 2O)]·3H 2O and the derived quadratic series (NH 4+) 1−x[ Ln1−xU x (C 2O 4) 2(H 2O)]·(3+ x) H 2O, Ln=Y, Pr–Sm, Gd, Tb

Single crystals of a new sodium ytterbium oxalate Na[Yb(C 2O 4) 2(H 2O)]·3H 2O ( 1) and six mixed lanthanide (III)–uranium (IV) oxalates (NH 4 +) 1− x [ Ln 1− x U x (C 2O 4) 2(H 2O)]·(3+ x) H 2O, Ln=Y, x = 0.47 ( 2), Ln=Pr, x = 0.42 ( 3), Ln=Nd, x = 0.60 ( 4), Ln=Sm, x = 0.55 ( 5), Ln=Gd, x = 0.25 ( 6) and Ln=Tb, x = 0.52 ( 7) have been grown using slow diffusion through silica gels. The crystal structures of all the compounds have been determined by single-crystal X-ray diffraction. For compound 1 the symmetry is monoclinic, space group Pc, cell dimensions a=8.559(2) Å, b=8.564(2) Å, c=14.938(3) Å, β=103.062(3), Z = 4 . The structure of 1 is isotypic with Na[Y(C 2O 4) 2(H 2O)]·3H 2O and consists of layers formed by four-membered rings of Yb connected through oxalate ions. The ytterbium atom is nine-coordinated by oxygen from four bis-bidentate oxalate ligands and one water molecule which alternate up and down the layer. Na + ions and supplementary water molecules are located between the layers. The six mixed lanthanide (III)–uranium (IV) oxalates, 2– 7, are isotypic, the symmetry is tetragonal, space group P4/ n, the unit cell parameters are in the range 8.7239(12)–8.9116(6) and 7.854(2)–7.9487(9) Å for a and c, respectively, Z = 2 . The structure of the six compounds is built from the same two-dimensional arrangement of alternating metallic and oxalate ions forming four-membered rings. The layers are similar to that observed in 1 and the mixed Ln(III)/U(IV) oxalate layers are obtained by partial substitution of Ln(III) by U(IV) in a nine-coordinated site, the charge surplus being compensated by removal of monovalent cations in the interlayer space. The ammonium ions and the water molecules are disordered in the same crystallographic site. Thus these compounds form the third series of mixed lanthanide (III)–uranium (IV) oxalates, the tetragonal one, that completes the two others previously reported, the hexagonal and the triclinic series.

Structural Polarity Induced by Cooperative Hydrogen Bonding and Lone-Pair Alignment in the Molecular Uranyl Iodate Na2[UO2(IO3)4(H2O)

Na2[UO2(IO3)4(H2O)] has been synthesized under mild hydrothermal conditions. Its structure consists of Na+ cations and [UO2(IO3)4(H2O)](2-) anions. The [UO2(IO3)4(H2O)](2-) anions are formed from the coordination of a nearly linear uranyl, UO2(2+), cation by four monodentate IO(3-) anions and a coordinating water molecule to yield a pentagonal bipyramidal environment around the uranium center. The water molecules form intermolecular hydrogen bonds with the terminal oxo atoms of neighboring [UO2(IO3)4(H2O)](2-) anions to yield one-dimensional chains that extend down the b axis. There are two crystallographically unique iodate anions in the structure of Na2[UO2(IO3)4(H2O)]. One of these anions is aligned so that the lone-pair of electrons is also directed along the b axis. The overall structure is therefore polar, owing to the cooperative alignment of both the hydrogen bonds and the lone-pair of electrons on iodate. The polarity of the monoclinic space group C2 (a = 11.3810(12) A, b = 8.0547(8) A, c = 7.6515(8) A, beta = 90.102(2) degrees , Z = 2, T = 193 K) found for this compound is consistent with the structure. Second-harmonic generation of 532 nm light from a 1064 nm laser source yields a response of approximately 16x alpha-SiO2.

Structural, Thermal and Dielectric Studies in Na2SeO4×Te (OH)6×H2O.

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Rubidium dimolybdate, Rb2Mo2O7, and caesium dimolybdate, Cs2Mo2O7

The crystal structures of dirubidium heptaoxodimolybdate, Rb(2)Mo(2)O(7), and dicaesium heptaoxodimolybdate, Cs(2)Mo(2)O(7), in the space groups Ama2 and P2(1)/c, respectively, have been determined for the first time by single-crystal X-ray diffraction. The structures represent two novel structure types of monovalent ion dimolybdates, A(2)Mo(2)O(7) (A = alkaline elements, NH(4), Ag or Tl). In the structure of Rb(2)Mo(2)O(7), Mo atoms are on a twofold axis, on a mirror plane and in a general position. One of the Rb atoms lies on a twofold axis, while three others are on mirror planes. Two O atoms attached to the Mo atom on a mirror plane are located on the same plane. Rubidium dimolybdate contains a new kind of infinite Mo-O chain formed from linked MoO(4) tetrahedra and MoO(6) octahedra alternating along the a axis, with two terminal MoO(4) tetrahedra sharing corners with each octahedron. The chains stack in the [001] direction to form channels of an approximately square section filled by ten-coordinate Rb ions. Seven- and eight-coordinate Rb atoms are located between chains connected by a c translation. In the structure of Cs(2)Mo(2)O(7), all atoms are in general positions. The MoO(6) octahedra share opposite corners to form separate infinite chains running along the c axis and strengthened by bridging MoO(4) tetrahedra. The same Mo-O polyhedral chain occurs in the structure of Na(2)Mo(2)O(7). Eight- to eleven-coordinate Cs atoms fill the space between the chains. The atomic arrangement of caesium dimolybdate has an orthorhombic pseudosymmetry that suggests a possible phase transition P2(1)/c-->Pbca at elevated temperatures.

The effect of increasing the excitation level of the sodium atom on the structure of the Na ∗Ar n polyatomic exciplexes

In this work, the geometrical structures, the formation energies, and electronic states of the Na( ms)Ar n polyatomic exciplexes with m = 3–6 and n = 2–5 are studied by using a quantum-classical method. The interaction potential between an electronically excited sodium atom and argon atoms are calculated by using a one-electron model involving electron–Ar and electron–Na + pseudopotentials, in which the Hamiltonian is diagonalized at every optimization step in the Basin Hopping algorithm. The relationship between the position of the electronically excited levels and the cluster geometry is investigated as a function of the excitation level and of the spatial extension of the excited electron orbital. We show that the equilibrium structures of the ground state Na(3s)Ar n and those of the electronically excited states Na(4s)Ar n , Na(5s)Ar n , and Na(6s)Ar n are significantly different. As a result of the detailed examination of the relationships between the geometrical structure and density distribution of the Na valence electron of the Na ∗Ar n with n = 2–5 polyatomic exciplexes, we can see that for the Na(4s)Ar n polyatomic exciplexes, the two extreme geometries, neutral Na(3s)Ar n and ionic Na +Ar n compete. It appears that none of them is the actual one. For Na(5s)Ar n and Na(6s)Ar n the valence electron is very weakly bound to the ionic core and described by a more diffused orbital so that the geometry and the formation energies of this excited state called Rydberg states converge towards those of the ionic cores.

Synthesis, Crystal Structure and Thermal Behavior of Na4 [B10O16(OH)2]×4H2O.

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Metal−Metal Bond or Isolated Metal Centers? Interaction of Hg(CN)2 with Square Planar Transition Metal Cyanides

Three adducts have been prepared from Hg(CN)(2) and square planar M(II)(CN)(4)(2)(-) transition metal cyanides (M = Pt, Pd, or Ni, with d(8) electron shell) as solids. The structure of the compounds K(2)PtHg(CN)(6).2H(2)O (1), Na(2)PdHg(CN)(6).2H(2)O (2), and K(2)NiHg(CN)(6).2H(2)O (3) have been studied by single-crystal X-ray diffraction, XPS, Raman spectroscopy, and luminescence spectroscopy in the solid state. The structure of K(2)PtHg(CN)(6).2H(2)O consists of one-dimensional wires. No CN(-) bridges occur between the heterometallic centers. The wires are strictly linear, and the Pt(II) and Hg(II) centers alternate. The distance d(Hg)(-)(Pt) is relatively short, 3.460 A. Time-resolved luminescence spectra indicate that Hg(CN)(2) units incorporated into the structure act as electron traps and shorten the lifetime of both the short-lived and longer-lived exited states in 1 compared to K(2)[Pt(CN)(4)].2H(2)O. The structures of Na(2)PdHg(CN)(6).2H(2)O and K(2)NiHg(CN)(6).2H(2)O can be considered as double salts; the lack of heterometallophilic interaction between the remote Hg(II) and Pd(II) atoms, d(Hg)(-)(Pd) = 4.92 A, and Hg(II) and Ni(II) atoms, d(Hg)(-)(Ni) = 4.61 A, is apparent. Electron binding energy values of the metallic centers measured by XPS show that there is no electron transfer between the metal ions in the three adducts. In solution, experimental findings clearly indicate the lack of metal-metal bond formation in all studied Hg(II)-CN(-)-M(II)(CN)(4)(2)(-) systems (M = Pt, Pd, or Ni).

Highlights from the Literature

Highlights from the Literature

Determination of the magnetic and nuclear structure of Ni _{2.17} Mn _{0.83} Ga

The structure of Ni2.17Mn0.83Ga has been investigated as a function of temperature using neutron powder diffraction. Above T = 310 K the compound has the cubic L21 structure, with lattice parameter a = 5.79 A, and with the excess nickel atoms occupying the vacant manganese sites. Magnetisation and resistivity measurements indicate a Curie temperature of T = 340 K with a further transition at T = 301 K associated with a structural phase transition. The martensitic phase was found to have a tetragonal structure with cell parameters a = b = 3.87 A and c = 6.47 A and space group I4/mmm. Although there is negligible change in atomic volume the lattice parameters a and b change by ∼5.5% and the c-axis by almost 12%. The large change in cell parameters and the relatively high transition temperature make the compound a promising candidate for applications.

Vanadium(IV and V) Complexes of Schiff Bases and Reduced Schiff Bases Derived from the Reaction of Aromatic o‐Hydroxyaldehydes and Diamines: Synthesis, Characterisation and Solution Studies

AbstractSeveral sal2en‐type reduced Schiff bases have been prepared from the reaction of 2 equiv. of salicylaldehyde (or derivatives) with ethylenediamine followed by reduction with NaBH4 and subsequently characterised. The water‐soluble ligands (SO3‐sal)2en and R(SO3‐sal)2en (SO3‐sal = salicylaldehyde‐5‐sulphonate) have been studied by pH potentiometry and 1H NMR spectroscopy and the protonation constants of R(SO3‐sal)2en have been determined. The Schiff bases are more susceptible to hydrolysis than the corresponding reduced Schiff bases. The crystal structures of H2(o‐van)2en and KH(o‐van)2en (o‐van = o‐vanillin) have been determined by X‐ray diffraction. The vanadium(IV) complexes have been prepared and characterised by magnetic measurements and IR, UV/Vis and EPR spectroscopy. The colours, magnetic susceptibilities and IR spectra of the new vanadium(IV) complexes of the reduced Schiff bases now obtained suggest oligomeric/polymeric structures for the compounds while the corresponding VIVO–Schiff‐base complexes are monomeric.The complexation of [VIVO]2+ and [VVO2]+ with R(SO3‐sal)2enin aqueous solution has been studied by pH potentiometry, UV/Vis as well as by EPR spectroscopy for the VIVO system and 1H and 51V NMR spectroscopy for the VVO2 system. Complex formation constants have been determined and binding modes have been proposed. N,N′‐ethylenebis(pyridoxylaminato) (Rpyr2en) has also been obtained and the structure of Na[VVO2(Rpyr2en)]·CH3OH·3H2O determined by X‐ray diffraction. The Rpyr2en2– ligand coordinates through both the N‐amine and O‐phenolate moieties in a symmetrical α‐cis type coordination mode, i.e. with both O‐phenolato donors cis to the O‐oxo atoms and trans to each other. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Structure refinements of Na0.8Ti1.2Ga4.8O10: X-ray diffraction analysis for the sodium ion distribution in a one-dimensional tunnel-like space

The structure of Na0.8Ti1.2Ga4.8O10 was determined by means of single-crystal X-ray diffraction at 173 and 123 K and reinvestigated at 299 K. The host structure containing one-dimensional tunnels was retained over the temperatures examined, while significant changes were observed in the probability density distribution of Na+ ions in the tunnel. The refinement based on the local structure model with the deviated Na+ ion neighboring the vacancy gave a similar result to that from the conventional model, but with reduced standard uncertainties of the structural parameters for the Na+ ions. The potential barrier for the Na+ ion hopping between adjacent cavities was estimated to be ca 30-40 meV from the joint probability density function of deviated Na+ ions.