There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

https://www.surfacesciencewestern.com/wp-content/uploads/2012/01/ass11_biesinger.pdf

Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Sc, Ti, V, Cu and Zn

A detailed analysis of the thermal expansion mechanism of graphite oxide to produce functionalized graphene sheets is provided. Exfoliation takes place when the decomposition rate of the epoxy and hydroxyl sites of graphite oxide exceeds the diffusion rate of the evolved gases, thus yielding pressures that exceed the van der Waals forces holding the graphene sheets together. A comparison of the Arrhenius dependence of the reaction rate against the calculated diffusion coefficient based on Knudsen diffusion suggests a critical temperature of 550 °C which must be exceeded for exfoliation to occur. As a result of their wrinkled nature, the functionalized and defective graphene sheets do not collapse back to graphite oxide but are highly agglomerated. After dispersion by ultrasonication in appropriate solvents, statistical analysis by atomic force microscopy shows that 80% of the observed flakes are single sheets.

Single Sheet Functionalized Graphene by Oxidation and Thermal Expansion of Graphite

Application of low-cost adsorbents for dye removal – A review

The rehydration of potassium acetate-intercalated kaolinite has been followed using a combination of X-ray diffraction and Raman microscopy. Dehydration of the fully expanded potassium acetate-intercalated kaolinite with initial d(001) spacing of 13.88 angstrom, in an atmosphere of nitrogen, shows the presence of three expanded kaolinite phases with d(001) spacings of 11.47, 9.6, and 9.2 angstrom. X-ray diffraction shows the existence of six expanded phases after one minute of rehydration with d spacings of 14.13, 11.56, 11.04, 9.88, 8.90, and 8.55 angstrom. Rehydration is rapid with the intercalation complex rehydrating in less than 21 min. Raman spectroscopy shows hydroxyl stretching bands at 3632 cm assigned to the inner hydroxyl and at 3601 cm attributed to the inner surface hydroxyl hydrogen bonded to the acetate ion when the intercalation complex is heated to 300°C under an atmosphere of nitrogen. The position of the inner hydroxyl band is observed at 3630 cm in the 298 K spectra, providing the intercalated kaolinite is not exposed to air. Phase changes of the intercalation complex are determined using the changes in intensity of the inner surface hydroxyl stretching bands. Phase changes are also observed through changes in intensity of the CqqO, C-C, and OCO Raman modes.

Rehydration of potassium acetate-intercalated kaolinite at 298 K

Two members of the arthurite mineral group, arthurite and whitmoreite A(Fe3+) 2 (XO 4 ) 2 (O,OH) 2 .4(H 2 O) where A = Cu(II), Zn(II), Pb(II) or Fe(II) and X = As, P, S have been studied using Raman spectroscopy. The minerals are based upon the combination of a divalent cation such as Cu(II), Zn(II), Pb(II) or Fe(II) and the trivalent cation, Fe(III), with counterbalancing of hydroxyl, arsenate, phosphate and sulphate anions. Such minerals lend themselves to analysis by Raman spectroscopy. For arthurite Cu(Fe 3 + ) 2 (AsO 4 ,PO 4 ,SO 4 ) 2 (O,OH) 2 .4(H 2 O), arsenate and hydroxyl anions are observed as well as minor phosphate and significant carbonate anions. For whitmoreite FeFe 2 (PO 4 ) 2 (OH) 2 .4(H 2 O), hydroxyls and phosphate are the major anions with significant sulphate and some carbonate. Raman spectroscopic analysis of two whitmoreite samples from the same mineral field suggests that differentiation by concentration of the anions occurs in the molecular assembly of the anions as crystallisation occurs as a function of the equilibrium conditions. Changing solution conditions are reflected in the varying compositions in the lattice.

/pdf/molecular-assembly-in-secondary-minerals-raman-spectroscopy-y5awuubvko.pdf

Molecular assembly in secondary minerals: Raman spectroscopy of the arthurite group species arthurite and whitmoreite

High resolution thermogravimetric analysis (HRTG) coupled to a gas evolution mass spectrometer has been used to study the thermal decomposition of zinc-modified takovites of formulae (NixZn6-xAl2(CO3)(OH)(16)center dot 4H(2)O) where x varies from 0 to 6. X-ray diffraction data indicate an increase in the crystallinity and decrease in the interlayer spacing of the materials with increase in the zinc composition. HRTG and mass spectrometry results indicate that water is lost in two major steps, with carbon dioxide coming off simultaneously at the second step. Further loss of CO2 occurred at higher temperatures due to decomposition of carbonate chemically bound to layer Zn2+ and Al3+ cations. The variations of the temperatures of dehydration and dehydroxylation/decarbonation with the zinc composition are discussed in terms of the effects of stabilisation of the layer structure, the electronegativity of the layer metals, the charge-to-size ratio of the layer cations and the layer-interlayer hydrogen bonding interactions.

/pdf/thermogravimetric-analysis-of-hydrotalcites-based-on-the-1qo31u4smk.pdf

Thermogravimetric analysis of hydrotalcites based on the takovite formula NixZn6-xAl2(OH)16(CO3)·4H2O

/pdf/single-crystal-raman-study-of-erythrite-co3-aso4-2-8h2o-3v0n3cviv2.pdf

Single Crystal Raman Study of Erythrite Co3(AsO4)2.8H2O

Specific surface reactions on kaolinite were investigated by deuterium exchange of the hydroxyl protons of kaolinite. The kaolinite samples were reacted with deuterium oxide for 48 h and 2.5 and 5 weeks, at various pH values (3, natural and 8) and at different temperatures (ambient, and 30, 60 and 100 °C). Analyses were performed using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The spectral results show that it is very difficult at room temperature to exchange the hydroxyl protons isotopically with deuterons at the surface of kaolinite. The temperature and the reaction time must be increased for successful exchange. It was found that the most suitable temperature for isotopic exchange was 60 °C. The pH did not significantly influence the deuteration. Only at high pH were changes of the OD bands in the DRIFT spectra observed. This study shows that it is possible to deuterate kaolinite without using intercalation. All three types of hydroxyl protons from the inner, inner surface and edge were exchanged.

Ray L. Frost

Papers

Rehydration of potassium acetate-intercalated kaolinite at 298 K

Molecular assembly in secondary minerals: Raman spectroscopy of the arthurite group species arthurite and whitmoreite

Thermogravimetric analysis of hydrotalcites based on the takovite formula NixZn6-xAl2(OH)16(CO3)·4H2O

Single Crystal Raman Study of Erythrite Co3(AsO4)2.8H2O

Isotopic exchange of kaolinite hydroxyl protons: a diffuse reflectance infrared Fourier transform spectroscopy study †