Ammonolyzed MoO3 Nanobelts as Novel Cathode Material of Rechargeable Li‐Ion Batteries

Through a moderate ammonolysis method, nanobelts of α‐MoO₃ can be modified to H_xMo(O, N)_3. When reaction temperatures are kept between 200–300 °C, gaseous NH₃ diffuses in‐between the oxide layers and reacts with terminal oxygen sites of MoO₃. As a consequence, hydrogen is introduced into the layers and bonded to terminal oxygen, and together with the effect of nitradation, the unit cell volume significantly shrinks mostly along the b axis. The modified compound H_xMo(O, N)₃ exhibits not only better electronic conductivity, but also faster lithium ion mobility than regular MoO₃. In addition, this ammonolyzed MoO₃ exhibits enhanced electrochemical performance beyond MoO₃. In the potential window 1.5–3.5 V, the specific capacity of H_xMo(O, N)₃ can reach more than 250 A h kg^?1 and was cycled 300 times without fading. It can be considered as a novel candidate cathode material with high specific charge for rechargeable Li‐ion batteries.     

Trichothecene Biosynthesis in Fusarium sporotrichioides: Origin of the Oxygen Atoms of T-2 Toxin

Mass spectral analysis of T-2 toxin formed during the growth of Fusarium sporotrichioides (ATCC 24043) in the presence of H₂¹⁸O showed incorporation of up to three ¹⁸O atoms per toxin molecule. The carbonyl oxygens of the acetates at C-4 and C-15 and of the isovalerate at C-8 were derived from H₂O. Toxin formed in the presence of ¹⁸O molecular oxygen incorporated up to six ¹⁸O atoms per toxin molecule. The overall incorporation was 78 and 92% of toxin molecules labeled for H₂¹⁸O and ¹⁸O₂ labeled samples, respectively. The oxygens of position 1, the 12,13-epoxide, and the hydroxyl groups at C-3, C-4, C-8, and C-15 were all derived from molecular oxygen.     

How relevant are S=O and P=O Double Bonds for the Description of the Acid Molecules H2SO3, H2SO4, and H3PO4, respectively?

The acid molecules H₂SO₃, H₂SO₄, and H₃PO₄ are usually drawn using "Lewis structures" which exhibit the octet extension by 3d-orbitals on sulfur and phosphorus, respectively. Thus, S=O and P=O double bonds are assumed to be formed. The natural d-orbital occupancies on S and P, however, were calculated to be as low as 0.1 e, and therefore, an octet extension can hardly be expected. After the natural bond orbitals (NBO) search procedure was forced to attempt to form different Lewis structures of bonds and lone pairs, we defined the optimal Lewis structure, if a dominant structure exists at all, by the maximum electronic charge in Lewis orbitals. Indeed, sulfur obeys the octet rule in the optimal zwitterionic Lewis structures and does not form S=O double bonds. No dominant resonance structure could be found for H₃PO₄ where polarized PO ?-bond and zwitterionic PO bond structures exhibit similar weights.     

ERRATA

Please replace the paragraph Culture of material in Materialand method on page 574 (Fujii, Shimmen and Tazawa), Vol. 19,No. 4 with the following corrected paragraph. Materials and methods Culture of material Spirogyra sp. used for the experiments was collected in theriver Kamogawa in Kyoto. Cylindrical cells composing the filamentwere 55 µm in diameter and 100–200 µm in length.Each cell usually had one spiral ribbon-like chloroplast. Thealga was cultured in slightly modified Reichardt's medium (27),1000 ml of which contained: 200 mg KNO₃, 20 mg K₂HPO₄, 10mgH₃BO₃, 6.6 mg FeSO₄?7H₂O, 25 mg Na₂EDTA (ethylenediamine tetraaceticacid disodium salt), 200 mg NaHCO₃, 50 mg CaSO₄?2H₂O, 10mg MgSO₄?7H₂O,0.5 mg ZnSO₄?7H₂O, 5mg MnCl₂?4H₂O, 24 µg Na₂MoO₄, 2 µgCoCl₂?6H₂O, 500 mg Tris. The pH was adjusted to 7.4 with HCl.The alga was cultured in a Petri dish at 20?1?C under a 16 hr–8hr light-dark regime. The light intensity was about 2000 lux.Under such conditions, the cells divided once a day fairly synchronously. Experimental solutions Artificial pond water (APW) containing 0.1 mM each of KCl, NaCland CaCl₂     

The effect of H<Subscript>3</Subscript>O<Superscript>+</Superscript> on the membrane morphology and hydrogen bonding of a phospholipid bilayer

At the 2017 meeting of the Australian Society for Biophysics, we presented the combined results from two recent studies showing how hydronium ions (H₃O⁺) modulate the structure and ion permeability of phospholipid bilayers. In the first study, the impact of H₃O⁺ on lipid packing had been identified using tethered bilayer lipid membranes in conjunction with electrical impedance spectroscopy and neutron reflectometry. The increased presence of H₃O⁺ (i.e. lower pH) led to a significant reduction in membrane conductivity and increased membrane thickness. A first-order explanation for the effect was assigned to alterations in the steric packing of the membrane lipids. Changes in packing were described by a critical packing parameter (CPP) related to the interfacial area and volume and shape of the membrane lipids. We proposed that increasing the concentraton of H₃O⁺ resulted in stronger hydrogen bonding between the phosphate oxygens at the water–lipid interface leading to a reduced area per lipid and slightly increased membrane thickness. At the meeting, a molecular model for these pH effects based on the result of our second study was presented. Multiple μs-long, unrestrained molecular dynamic (MD) simulations of a phosphatidylcholine lipid bilayer were carried out and showed a concentration dependent reduction in the area per lipid and an increase in bilayer thickness, in agreement with experimental data. Further, H₃O⁺ preferentially accumulated at the water–lipid interface, suggesting the localised pH at the membrane surface is much lower than the bulk bathing solution. Another significant finding was that the hydrogen bonds formed by H₃O⁺ ions with lipid headgroup oxygens are, on average, shorter in length and longer-lived than the ones formed in bulk water. In addition, the H₃O⁺ ions resided for longer periods in association with the carbonyl oxygens than with either phosphate oxygen in lipids. In summary, the MD simulations support a model where the hydrogen bonding capacity of H₃O⁺ for carbonyl and phosphate oxygens is the origin of the pH-induced changes in lipid packing in phospholipid membranes. These molecular-level studies are an important step towards a better understanding of the effect of pH on biological membranes.     

Orientation of Pea Stem Mitochondrial H+-Pyrophosphatase and Its Different Characteristics from the Tonoplast Counterpart

Proton pumping pyrophosphatase (H⁺-PP_iase) of pea stem mitochondriaappears to be localized on the inner surface of the inner membrane.Aminohexanediphosphonate and dichloromethylenediphosphonateexert different inhibitory effects on this activity and on thatof tonoplast. Antibody raised against membrane-bound mitochondrialH⁺-PP_iase does not react with tonoplast vesicles. Thus, plantmitochondrial H⁺PP_iase seems to have a molecular structure differentfrom that of vacuolar H⁺-PP_iase. (Received August 2, 1996; Accepted October 18, 1996)     

Density functional study of H<Subscript>2</Subscript>O molecule adsorption on α-U(001) surface

Periodic density functional theory (DFT) calculations were performed to investigate the adsorption of H₂O on U(001) surface. The metallic nature of uranium atom and different adsorption sites of U(001) surface play key roles in the H₂O molecular dissociate reaction. The long-bridge site is the most favorable site of H₂O-U(001) adsorption configuration. The triangle-center site of the H atom is the most favorable site of HOH-U(001) adsorption configuration. The interaction between H₂O and U surface is more evident on the first layer than that on any other two sub-layers. The dissociation energy of one hydrogen atom from H₂O is ?1.994 to ?2.215 eV on U(001) surface, while the dissociating energy decreases to ?3.351 to ?3.394 eV with two hydrogen atoms dissociating from H₂O. These phenomena also indicate that the O_ads can promote the dehydrogenation of H₂O. A significant charge transfer from the first layer of the uranium surface to the H and O atoms is also found to occur, making the bonding partly ionic.     

Solution structure of molybdic acid from Raman spectroscopy and DFT analysis

Protonation of produces the well-characterized polymolybdates, but at concentrations below 10⁻³ M the dominant species is monomeric molybdic acid, H₂MoO₄. It is likely to be the species adsorbed on manganese oxide, a process thought to control levels in the ocean, because of the strong proton dependence of adsorption. The molecular structure of H₂MoO₄ is elusive, since it occurs only in dilute solutions. Using 244 nm laser excitation, near resonance with O → Mo charge-transfer electronic transitions of H₂MoO₄, we have detected a 919 cm⁻¹ Raman band assignable to ν_sMoO. Using DFT, we have computed geometries and vibrational modes for the various structures consistent with the H₂MoO₄ formula. We tested the computations on a series of Mo(VI) oxo complexes with known vibrational frequencies, at several levels of theory. Best agreement with experimental values, at reasonable computational cost, was obtained with the B3LYP functional, employing a LANL2DZ ECP basis set for Mo and the 6-311+G(2df,p) basis set for O and H. Among the possible H₂MoO₄ structures only those based on the MoO₃ unit, with one, two or three coordinated water molecules, gave a scaled frequency for ν_sMoO that was within two standard deviations of 919 cm⁻¹. Best agreement was obtained for MoO₃(H₂O)₃. The MoO₂ and MoO structures gave frequencies that were too high. The Mo(OH)₆ structure could be excluded, because its vibrational frequencies shift down strongly upon H/D exchange, whereas the 919 cm⁻¹H₂MoO₄ band shifts up 1 cm⁻¹ in D₂O.     

DFT study of CO<Subscript>2</Subscript> and H<Subscript>2</Subscript>O co-adsorption on carbon models of coal surface

The moisture content of coal affects the adsorption capacity of CO₂ on the coal surface. Since the hydrogen bonds are formed between H₂O and oxygen functional group, the H₂O cluster more easily adsorbs on the coal micropore than CO₂ molecule. The coal micropores are occupied by H₂O molecules that cannot provide extra space for CO₂ adsorption, which may leads to the reduction of CO₂ adsorption capacity. However, without considering factors of micropore and oxygen functional groups, the co-adsorption mechanisms of CO₂ and adsorbed H₂O molecule are not clear. Density functional theory (DFT) calculations were performed to elucidate the effect of adsorbed H₂O to CO₂ adsorption. This study reports some typical coal-H₂O···CO₂ complexes, along with a detailed analysis of the geometry, energy, electrostatic potential (ESP), atoms in molecules (AIM), reduced density gradient (RDG), and energy decomposition analysis (EDA). The results show that H₂O molecule can more stably adsorb on the aromatic ring surface than CO₂ molecule, and the absolute values of local ESP maximum and minimum of H₂O cluster are greater than CO₂. AIM analysis shows a detailed interaction path and strength between atoms in CO₂ and H₂O, and RDG analysis shows that the interactions among CO₂, H₂O, and coal model belong to weak van der Waals force. EDA indicates that electrostatic and long-range dispersion terms play a primary role in the co-adsorption of CO₂ and H₂O. According to the DFT calculated results without considering micropore structure and functional group, it is shown that the adsorbed H₂O can promote CO₂ adsorption on the coal surface. These results demonstrate that the micropore factor plays a dominant role in affecting CO₂ adsorption capacity, the attractive interaction of adsorbed H₂O to CO₂ makes little contribution.     

Oxygen Adsorption on Zr(0001): An ab Initio Study

Abstract

The main goal of this paper is to study the oxygen adsorption on the Zr(0001) surface using first-principles total-energy calculations based on density-functional theory. We present preliminary results which concern the atomic oxygen adsorption on the Zr(0001) surface. We first report a static study where we calculate the atomic structure and adsorption energy for oxygen occupying various surface and subsurface sites at three different coverages: Θ = 1/4, 1/2, and 1 ML. We find that oxygen atoms are preferentially adsorbed into the octahedral holes between the 2nd and 3rd metallic layers. We secondly perform ab initio molecular dynamics calculations for the Zr(0001) – (3 × 3) – O system to show how the oxygen can penetrate through the surface and how it finally reaches its equilibrium position, trapped between the 1st and 2nd zirconium layers.     

Synthesis and spectroscopic studies of paramagnetic molybdenum(V) thioglycolate

A paramagnetic binuclear molybdenum(V) thioglycolate of composition Mo₂(L)₅(H₂O)₂ (H₂L = CH₂SHCOOH, thioglycolic acid) has been synthesized by direct reduction of molybdenum(VI) oxide hydrate (MoO₃ · H₂O) with thioglycolic acid in an argon atmosphere. Based on the combined results of elemental analysis, EPR, IR ¹H NMR, electronic spectra, magnetic susceptibility, cyclic voltametry and x-ray photoelectron spectral measurements, it is concluded that in the title compound, both the molybdenum atoms are in pentavalent state with octahedral coordination through both sulphur and oxygen atoms of thioglycolic acid and water molecules. The two molybdenum ions have slightly different coordination environments due to bridging thioglycolate ions.     

Modeling and scale-up of the unsterile scleroglucan production process with Sclerotium rolfsii ATCC 15205

An empirical model was applied to describe the growth related formation of scleroglucan in batchwise cultivation of Sclerotium rolfsii. In this case, the level of oxygen supply controls the carbon flux into glucan, biomass, and CO₂ evolution and therefore determines the yield coefficients Y_Glucan/BDM and Y_BDM/O2. It was observed that scleroglucan formation is enhanced under microaerobic conditions. However, as the empirical model and data of actual batch cultivations show, different maxima exist for product end concentration [g/l] and volumetric productivity [g/ld] depending on the total oxygen uptake during cultivation. A sufficient bulk mixing of the highly viscous culture suspension becomes particularly important during large-scale cultivations. In addition, the scleroglucan production process proved to be shear sensitive. A correlation between the attainable molecular weight of the glucan and the stirrer tip velocity in bioreactors of different sizes is presented. For all these reasons, a scale-up of this process is very complex. Large-scale cultivations under microaerobic conditions, aiming for maximum product end concentration, were slowed down by poor bulk mixing leading to a lower carbon flux into glucan formation. On the other hand, a scale-up designed for maximum volumetric productivity using high oxygen supply was successfully conducted up to a reactor volume of 1.500 l. To minimize the loss in product quality (molecular weight of the glucan) due to high stirrer tip velocities, a mixing concept was developed employing reduced agitation combined with maximum aeration to secure a sufficient axial bulk mixing in the reactor.     

Molybdenum complexes with O,N,S donor ligands as models for active sites in oxotransferases and hydroxylases

A series of homologous mononuclear dioxomolybdenum complexes were prepared and fully characterized with structurally related thiosemicarbazone ligands supplying a tridentate O,N,S donor set to the central metal atom. The ligands are derived from the prototype 2-hydroxybenzaldehyde-4-triphenylmethylthiosemicarbazone (H₂L). Within this series the crystal structures of 11 complex compounds [MoO₂(LRⁿ)(dmf)] and [MoO₂(LRⁿ)(MeOH)] were determined showing characteristic differences in the gross structural properties of the central metal core. From the variation of substituents in this ligand library the influences of electronic ligand effects on the spectroscopic, electrochemical, and functional properties of these biomimetic model complexes for molybdenum-containing oxotransferases are reported.     

Soluble minerals in chemical evolution

The adsorption of 5-AMP and 5-CMP was studied in saturated solutions of several soluble mineral salts (NaCl, Na₂SO₄, MgCl₂·6H₂O, MgSO₄·7H₂O, CaCl₂·2H₂O, CaSO₄·2H₂O, SrCl₂·6H₂O, SrSO₄, and ZnSO₄·7H₂O) as a function of pH, ionic strength, and surface area of the solid salt. The adsorption shows a pH dependence; this can be correlated with the charge on the nucleotide molecule which is determined by the state of protonation of the N-1 nitrogen of 5-AMP or N-3 nitrogen of 5-CMP and the phosphate oxygens. The adsorption which results from the binding between the nucleotide molecule and the salt surface is proposed as being due to electrostatic forces. It was concluded that the adsorption was reversible in nature. The adsorption shows a strong dependence upon ionic strength and decreases with increasing ionic strength. Surface area is shown to be an important factor in evaluating and comparing the magnitude of adsorption of nucleotides onto various mineral salts. The implications of the results of the study are discussed in terms of the importance of soluble mineral salts as adsorption sites in the characterization of the adsorption reactions of an adsorbed template in biogeochemical cycles.     

Synthesis, structure and characterization of a new tetrameric tungsten-oxo complex [WO2Cl2(THF)]4

WOCl₄ reacts with (Me₃Si)₂O and excess THF to give [WO₂Cl₂(THF)]₄ (1), a new tetrameric tungsten(VI)-oxo complex, which was characterized and crystal structure was determined by X-ray crystallography. Complex 1 has a roughly square planar tetranuclear structure bridged by μ-oxo ligands. Each tungsten atom is coordinated by two bridging oxygens, one terminal oxygen, two “axial” chlorine atoms and one “equatorial” O-bonded THF ligand. One of the two μ-oxo ligands is similar to the terminal oxygen atom and the other one is similar to the coordinated oxygen atom of the THF ligand, respectively, which confirmed a previous proposal. Four WO₃Cl₂(THF) octahedral are associated by sharing corners. Complex 1 is different from three known tetrameric tungsten analogues in its structural arrangement and properties.     

DFT studies of acrolein molecule adsorption on pristine and Al- doped graphenes

The ability of pristine graphene (PG) and Al-doped graphene (AlG) to detect toxic acrolein (C₃H₄O) was investigated by using density functional calculations. It was found that C₃H₄O molecule can be adsorbed on the PG and AlG with adsorption energies about ?50.43 and – v30.92 kcal mol^?1 corresponding to the most stable configurations, respectively. Despite the fact that interaction of C₃H₄O has no obvious effects on the of electronic properties of PG, the interaction between C₃H₄O and AlG can induce significant changes in the HOMO/LUMO energy gap of the sheet, altering its electrical conductivity which is beneficial to sensor designing. Thus, the AlG may be sensitive in the presence of C₃H₄O molecule and might be used in its sensor devices. Also, applying an external electric filed in an appropriate orientation (almost stronger than 0.01 a.u.) can energetically facilitate the adsorption of C₃H₄O molecule on the AlG.     

叶片水H218O富集的研究进展

 植物叶片水H₂¹⁸O富集对大气中O₂和CO₂的¹⁸O收支有着重要影响。蒸腾作用使植物叶片水H₂¹⁸O富集, 而植物叶片水H₂¹⁸O富集的程度主 要受大气水汽δ¹⁸O和植物蒸腾水汽δ¹⁸O的影响。过去, 通过引入稳态假设(蒸腾δ¹⁸O等于茎水δ¹⁸O)得到Craig-Gordon模型的闭合形式, 或 将植物整个叶片水δ¹⁸O经过Péclet效应校正后得到植物叶片水δ¹⁸O的富集程度。然而, 在几分钟到几小时的短时间尺度上, 植物叶片蒸腾 δ¹⁸O是变化的, 稳态假设是无法满足的。最近成功地实现了对大气水汽δ¹⁸O和δD的原位连续观测, 观测精度(小时尺度)可达到甚至优于稳定 同位素质谱仪的观测精度。在非破坏性条件下, 高时间分辨率和连续的大气水汽δ¹⁸O和蒸腾δ¹⁸O的动态观测, 将提高植物叶片水H₂¹⁸O富集的 预测能力。该文综述了植物叶片水H₂¹⁸O富集的理论研究的新进展、研究焦点和观测方法所存在的问题, 旨在进一步加深理解植物叶片水H₂¹⁸O 富集的过程及其机制。     

Room Temperature Preparation of Surface-Clean Hydrogen-Doped Plasmonic Molybdenum Oxide as a High-Efficient and Degradable Reactive Oxygen Species Scavenger

Considerable efforts have been made to develop reactive oxygen species (ROS) scavengers for removing high level of ROS. However, most of the reported ROS scavengers are nondegradable and involve harsh reaction conditions as well as utilize various surface ligands. In order to overcome these drawbacks, in the present work, we develop a facile and mild synthesis avenue for preparation of surface-clean hydrogen-doped molybdenum oxide (H_0.34MoO₃) via simply mixing MoO₃ dispersion with aluminum foil under an acidic environment without any surface capping reagents at room temperature. The resulting H_0.34MoO₃ can act as a broad-spectrum ROS scavenger, including ^.OH, H₂O₂, O₂⁻, and ¹O₂ as well as 2, 2-diphenyl-1-picrylhydrazyl (DPPH). The free radical scavenging activity of H_0.34MoO₃ achieves as high as 71.6% and 99.1% for ^.OH and DPPH scavenging, which is comparable and superior to that of ascorbic acid that is a classic free radical scavenger. More significantly, the resulting H_0.34MoO₃ is degrade, which can be degraded into molybdate ions under a neutral environment (pH 7.4).

     

Oxydiacetato complexes of thorium(IV), the crystal structures of tetra-aquo bis(oxydiacetato)thorium(IV) hexahydrate and di(sodium nitrate) disodium tris(oxydiacetato)thorium(IV)

The crystal and molecular structures of Th(oda)₂(H₂O)₄·6H₂O (1) and Na₂[Th(oda)₃]·2NaNO₃ (2) (oda = oxydiacetate) have been determined from three-dimensional X-ray diffraction data and refined by least squares to R = 0.049 and Rw = 0.049 for 2265 independent reflections for (1) and to R = 0.024 and Rw = 0.023 for 2196 independent reflections for (2).Crystal parameters are as follows: (1), tetragonal, space group P4₁2₁2, a = 10.335(2), c = 20.709(5) Å and Z = 4; (2), monoclinic, space group C2/c, a = 17.096(5), b = 9.451(2), c = 16.245(4) Å, β = 107.8(1) and Z = 4.In both compounds the thorium atom lies on a crystallographic two-fold axis. The co-ordination number for thorium in (1) is 10 (bicapped square antiprism geometry), the compound is monomeric, the two oda ligands are tridentate to the metal, and four water molecules complete the coordination sphere; in thorium (2) the coordination number is 9 (tricapped trigonal prism geometry) with three oda ligands tridentate to the metal, the [Th(oda)₃]^2? and NO₃^? anions are held together through the sodium ions which are coordinated both to the oda carboxylic oxygens and to the nitrate oxygens.The ThO coordination distances are: in (1) 2.411(8), 2.414(9) for the carboxylic oxygens, 2.479(10) and 2.486(8) for water molecules and 2.697(9) for the etheric oxygen and in (2) 2.384(3), 2.402(4) and 2.402(4) for the carboxylic oxygens, 2.559(5) and 2.562(4) Å for the etheric oxygens.