Electron transfer at tetrahedral cobalt(II). Part 1. Kinetics of bromate ion reduction

Summary The bromate ion reduction by 12-tungstocobaltate(II) anion has been investigated. The reaction obeys the empirical rate law:-d[reductant]/dt=5(a+b[H⁺]²)[BrO ₃ ^– ][reductant]: where a=(2.49±0.18)×10^–4M^–1 s^–1, b=(4.65±0.20)×10^–5M^–3s^–1 at 24.5±0.1°C [H⁺]=0.05–1.50M and I=2.0M (NaClO₄). This rate law is interpreted in terms of parallel reactions of BrO ₃ ^– and H₂BrO ₃ ⁺ . On the basis of the observed anion catalysis, substitution intertness of the reductant and Marcus type linear free energy relations, the outer sphere mechanism is proposed for both pathways.     

An adeno-associated viral vector transduces the rat hypothalamus and amygdala more efficient than a lentiviral vector

Background  

This study compared the transduction efficiencies of an adeno-associated viral (AAV) vector, which was pseudotyped with an AAV1 capsid and encoded the green fluorescent protein (GFP), with a lentiviral (LV) vector, which was pseudotyped with a VSV-G envelop and encoded the discosoma red fluorescent protein (dsRed), to investigate which viral vector transduced the lateral hypothalamus or the amygdala more efficiently. The LV-dsRed and AAV1-GFP vector were mixed and injected into the lateral hypothalamus or into the amygdala of adult rats. The titers that were injected were 1 × 10⁸ or 1 × 10⁹ genomic copies of AAV1-GFP and 1 × 10⁵ transducing units of LV-dsRed.     

AN INVESTIGATION INTO THE BALANCE OF PRESCRIPTION,EXPERIMENT AND PLAY WHEN LEARNING ABOUT THE PROPERTIES OF QUADRATIC FUNCTIONS WITH ICT

This paper will draw on research being developed within the Teaching and Learning strand of the ESRC InterActive Education: Learning in the Information Age project which is examining the ways in which new technologies can be used in educational settings to enhance learning. It will focus on the learning and understanding of quadratic functions using a graphical software package and includes a discussion of how the structuring of the activities influences the nature of the learning environment. The potential affordance that the software provides for experiment and play is highlighted in relation to the teacher's role in shaping the tasks to effectively make good use of this mode of learning.     

Mild solutions of evolution quantum stochastic differential equations with nonlocal conditions

We study existence of a unique mild solution of evolution quantum stochastic differential equations with nonlocal conditions under the strong topology. Using the method of successive approximations, we do not need to transform the nonlocal problem to a fixed point form. The evolution operator A generates a family of semigroup that are continuous. Nonlocal conditions allow additional measurements of certain phenomena that cannot be captured by the traditional initial conditions. We show that under some given conditions, the mild solution is unique and also stable. The method applied here is much easier when compared with previous methods used in literature.     

The ‘invisible science’: operational research for the British Armed Forces after 1945

This paper presents an original account of the contribution of operational research (OR) to the formulation of tactics and strategy on behalf of the British Armed Forces in the four decades after 1945. The main focus is on the Cold War in the European theatre, where OR analysts devoted considerable time and effort to the modelling of warfare on behalf of the British Army of the Rhine. In the absence of combat data for nuclear weapons, OR analysts devised a sequence of war games which evolved in conformity with the development of NATO strategy in relation to the Warsaw Pact. Again in the context of the Cold War, the paper analyses the role of OR in relation to the early V bomber force and the introduction of ‘global war studies’ on behalf of the Royal Navy. The paper also comments on the organisational structure of British military OR following on the creation of a centralised OR facility within the Ministry of Defence in 1965. In conclusion, the paper notes the sea-change in military OR following the end of the Cold War in 1990 and the onset of a period of sustained ‘asymmetric’ military operations in the former Yugoslavia, the Middle East and Afghanistan.     

Kinetic Enhancement of Direct Hydrogenation of MgB2 to Mg(BH4)2 upon Mechanical Milling with THF,MgH2, and/or Mg

Modification of magnesium diboride, MgB₂, by mechanical milling with THF, MgH₂, and/or Mg results in a lowering of the conditions required for its direct, bulk hydrogenation to magnesium borohydride, Mg(BH₄)₂, by 300 bar and 100 °C. Following mechanical milling with MgH₂ or THF and Mg, MgB₂ can be hydrogenated to Mg(BH₄)₂ at 300 °C under 700 bar of H₂ while achieving ∼54–71 % conversion to the borohydride. The discovery of a means of dramatically lowering the conditions required for the hydrogenation of MgB₂ is an important step towards the development of a practical onboard hydrogen storage system based on hydrogen cycling between Mg(BH₄)₂ and MgB₂. We suggest that mechano-milling with THF, Mg, and/or MgH₂ may possibly introduce defects in the MgB₂ structure which enhance hydrogenation. The ability to activate the MgB₂ through the introduction of structural defects transcends its relevance to hydrogen storage, as a method of overcoming its chemical inertness provides the key to harnessing other interesting properties of this material.     

Raman spectroscopic study of the uranyl carbonate mineral voglite

Raman spectroscopy, complemented with infrared spectroscopy, was used to study the uranyl carbonate mineral voglite. The mineral has the formula Ca₂Cu²⁺ [(UO₂)(CO₃)₃](CO₃)^•6H₂O, and bands attributed to these vibrating units are readily identified in the Raman spectrum. Symmetric stretching modes at 836 and 1094 cm⁻¹ are assigned to ν₁(UO₂)²⁺ and ν₁(CO₃)²⁻ units, respectively. The ν₃ antisymmetric stretching modes of (UO₂)²⁺ are not observed in the Raman spectrum but may be readily observed in the infrared spectrum at 898 cm⁻¹. The ν₃ antisymmetric stretching mode of (CO₃)²⁻ is observed in the Raman spectrum at 1369 cm⁻¹ as a low intensity band as is also the ν₃(CO₃)²⁻ infrared modes at 1362, 1425, 1509 and 1566 cm⁻¹. No ν₂(CO₃)²⁻ Raman bending modes are observed for voglite. The Raman band at 749 cm⁻¹ and the two infrared bands at 747 and 709 cm⁻¹ are assigned to the ν₄(CO₃)²⁻ bending modes. U O bond and O H…O bond lengths in the structure of voglite were inferred from the infrared and Raman spectra. Copyright © 2007 John Wiley & Sons, Ltd.     

A facile preparation of some novel class II mesoionic xanthine acyclonucleosides

The synthesis of the first examples of Class II mesoionic xanthine acyclonucleosides is described. A series of mesoionic anhydro-(8-methoxyalkyl-5-hydroxy-7-oxothiazolo[3,2-a]pyrimidinium hydroxides), Class II mesoionic analogs isoconjugate with xanthine, were prepared by the thermal condensation of methoxyalkyl-2-aminothiazoles with substituted bis(2,4,6-trichlorophenyl)malonic esters. The memoxyalkyl-2-aminothiazoles were prepared via an aromatic nucleophilic substitution reaction between 2-bromothiazole and the appropriate methoxyalkylamine in excess. The resulting 8-methoxyalkyl-substituted mesoionic xanthines were demethylated using iodotrimethylsilane in acetonitrile at room temperature to afford the corresponding mesoionic anhydro-(8-hydroxyalkyl-5-hydroxy-7-oxothiazolo[3,2-a]pyrimidinium hydroxides) as the Class II mesoionic xanthine acyclonucleosides.     

Sulfate intercalated layered double hydroxides prepared by the reformation effect

The removal of the sulfate anion from water using synthetic hydrotalcite (Mg/Al LDH) was investigated using powder X-ray diffraction (XRD) and thermogravimetric analysis (TG). Synthetic hydrotalcite Mg₆Al₂(OH)₁₆(CO₃)·4H₂O was prepared by the co-precipitation method from aluminum and magnesium chloride salts. The synthetic hydrotalcite was thermally activated to a maximum temperature of 380 °C. Samples of thermally activated hydrotalcite where then treated with aliquots of 1000 ppm sulfate solution. The resulting products where dried and characterized by XRD and TG. Powder XRD revealed that hydrotalcite had been successfully prepared and that the product obtained after treatment with sulfate solution also conformed well to the reference pattern of hydrotalcite. The d₍₀₀₃₎ spacing of all samples was found to be within the acceptable region for a LDH structure. TG revealed all products underwent a similar decomposition to that of hydrotalcite. It was possible to propose a reasonable mechanism for the thermal decomposition of a sulfate containing Mg/Al LDH. The similarities in the results may indicate that the reformed hydrotalcite may contain carbonate anion as well as sulfate. Further investigation is required to confirm this.