The Raman spectra of a tubular halloysite originating from Matauri Bay, New Zealand, have been obtained using a Renishaw 1000 Raman microscope system. The Raman microprobe enables the Raman spectra of crystals as small as 0.8 μm diameter to be obtained over the complete wavelength range and allows spectral variations along the different crystal axes to be studied. Three bands in the hydroxyl stretching region were observed at 3616.5, 3623.4 and 3629.7 cm-1 and are attributed to the inner hydroxyls of the shared lower plane of the octahedral sheet of the halloysite. Two bands at 3698.2 and 3705 cm−1 were obtained for the outer hydroxyls of the unshared outer octahedral plane. The relative intensity of the 3629.7 cm−1 band varied according to the tube orientation. Lattice vibrations of the halloysite were also found to be orientation-dependent.

Changes in the molecular structure of a highly ordered kaolinite, intercalated with urea and potassium acetate, have been studied using Raman microscopy. A new Raman band, attributed to the inner surface hydroxyl groups strongly hydrogen bound to the acetate, is observed at 3605 cm-1 for the potassium acetate intercalate with the consequential loss of intensity in the bands at 3652, 3670, 3684 and 3693 cm-1. Remarkable changes in intensity of the Raman spectral bands of the low-frequency region of the kaolinite occurred upon intercalation. In particular, the 144 and 935 cm-1 bands increased by an order of magnitude and were found to be polarized. These spectroscopic changes provide evidence for the inner surface hydroxyl group-acetate bond being at an angle approaching 90° to the 001 face. Decreases in intensity of the bands at 243, 271 and 336 cm-1 were observed. The urea intercalate shows additional Raman bands at 3387, 3408 and 3500 cm-1 which are attributed to N-H vibrations after formation of the urea-kaolinite complex. Changes in the spectra of the inserting molecules were also observed.

The Fourier transform Raman spectra of the kaolinite minerals have been measured in the 50–3800 cm−1 region using near infrared spectroscopy. Kaolinites are characterized by remarkably intense bands in the 120–145 cm−1 region. These bands, attributed to the O-Si-O and O-Al-O symmetric bending modes, are both polymorph and orientation dependent. The 200–1200 cm−1 spectral range is a finger-print region for clay minerals and each kaolinite clay has its own characteristic spectrum. The structure of clays is fundamentally determined by the position of hydroxyl groups. Fourier-transform Raman spectroscopy readily enables the hydroxyl stretching region to be examined allowing identification of the component bands. The advantages of FT-Raman spectroscopy are shown to enhance the study of the kaolinite structure.

The adsorption of the silane coupling agents N-(2-amino-ethyl)-3-aminopropyl- trimethoxysilane (Z-6020), N-(2-(vinylbenzyl-amino)-ethyl)-3-amino-propyl-trimethoxysilane (Z-6032) and 3-glycidoxy-propyl-trimethoxysilane (Z-6040) onto the surface of kaolinite has been studied using the solvents water and ethanol. The adsorbed silanes were analysed using diffuse reflectance Fourier transform infrared (DRIFT) spectroscopy and FT-Raman spectroscopy. When the silane coupling agents are dissolved in water, silanol groups are formed. Raman spectra of aqueous solutions of the silanes show that condensation of the silanols into oligomers occurred. The peak at 1000 cm-1 assigned to Si–O–Si vibrations indicates that polymerization has occurred. A similar behaviour is observed when the silanes are dissolved in ethanol. The DRIFT spectra show that the silane coupling agents adsorb onto the surface of kaolinite. It is proposed that the oligomers are bonded to the kaolinite surface only by hydrogen bondings with no covalent bonds formed.

Microstructural (fabric, forces and composition) changes due to hydrocarbon contamination in a clayey soil (glacial till) were studied using scanning electron microscopy (microfabric analysis), atomic force microscopy (force measurement) and a sedimentation bench test (particle size measurements). Non-polluted and polluted glacial till from NE Poland (in the area of a fuel terminal) were used for the study. Electrostatic repulsive forces in the polluted samples were much lower than in non-polluted samples. In comparison with non-polluted samples, the polluted samples exhibited lower electric charge, attractive forces on approach and strong adhesion on withdrawal. The results of the sedimentation tests indicate that clay particles form larger aggregates and settle out of the suspension rapidly in diesel oil. In non-polluted soil, the fabric is strongly aggregated – dense packing, dominating face-to-face and edge-to-edge types of contacts, clay film tightly adhering to the surface of larger grains and interparticle pores are more common. In polluted soil the clay matrix is less aggregated – loose packing, dominating edge-to-face types of contacts and inter-micro-aggregate pores are more frequent. Substantial differences were observed in the morphometric and geometrical parameters of the pore space. The polluted soil micro-fabric proved to be more isotropic and less oriented than in non-polluted soil. The polluted soil, in which electrostatic forces were suppressed by hydrocarbon interaction, displays more open porosity and larger voids than non-polluted soil, which is characterized by the occurrence of strong electrostatic interaction between the clay particles.

Raman microscopy of the kaolinite polymorphs was used to study single crystals and bundles of aligned crystals of kaolinite. The spectra of the hydroxyl stretching region were both sample and orientation dependent. Kaolinites can be classified into two groups according to the ratio of the intensities of the 3685 and 3695 cm−1 bands. No relationship was found between the d-spacing and the crystal domain size measurement from the 001 reflection and the Raman spectral intensities indicating the Raman spectra are independent of d-spacing and crystallinity. However, a relationship of the crystallinity in the a-b direction and intensities of the 3685 and 3695 cm−1 bands indicate that the relative position of one layer to the other determines the position of the inner surface hydroxyl groups and the hydrogen bonding with the oxygen of the opposite layer. A new hypothesis based on symmetric and non-symmetric hydrogen bonding of the inner surface hydroxyl groups is proposed to explain the two inner surface hydroxyl bands centred at 3685 and 3695 cm−1. The bands at 3670 and 3650 cm−1 are described in terms of the out-of-phase vibrations of the in-phase vibrations at 3695 and 3685 cm−1.

Stichtite is a naturally occurring layered double hydroxide (LDH) with the ideal chemical formula Mg6Cr2CO3(OH)16.4H2O. It has received less attention in the literature than other LDHs and is often described as a rare mineral; however, abundant deposits of the mineral do exist. In this article we aim to review a number of significant publications concerning the mineral stichtite, including papers covering the discovery, geological origin, synthesis and characterizsation of stichtite. Characterization techniques reviewed include powder X-ray diffraction (XRD), infrared spectroscopy (IR), near infrared spectroscopy (NIR), Raman spectroscopy (Raman), thermogravimetry (TG) and electron microprobe analysis.

Kaolinite hydroxyls in dimethylsulphoxide-intercalated (DMSO-intercalated) kaolinites have been determined using Raman spectroscopy at 298 and 77 K. The inner surface hydroxyl frequencies at 3650, 3670, 3684 and 3693 cm-1 move to higher wavenumbers upon cooling to 77 K and are observed at 3659, 3676, 3692 and 3702 cm-1. The inner hydroxyl frequency is at 3620 cm-1 at 298 K and is at 3615 cm-1 at 77 K. Upon intercalation with DMSO, additional bands are found at 3660, 3536 and 3501 cm-1 for the low-defect kaolinite and at 3664, 3543 and 3509 cm-1 for the high-defect kaolinite at 298 K. The 3660 cm-1 band at 298 K is resolved into two bands at 3658 and 3663 cm-1 at 77 K for the low-defect kaolinite and these bands are assigned to the inner surface hydroxyl groups, hydrogen-bonded to the DMSO molecule. It is proposed that the DMSO molecule exists with two different orientations in the intercalate and these two molecular forms are differentiated by the OH-stretching bands of the inner surface hydroxyl groups. This band for the high-defect kaolinite is found at 3664 cm-1 at 298 K and resolves into two bands at 3664 and 3673 cm-1 at 77 K.

The kinetics of structural change of a highly ordered kaolinite intercalated with potassium acetate have been studied through both intercalation and deintercalation. Deintercalation of the intercalated kaolinite, brought about by washing for different time intervals was followed by both X-ray diffraction and Raman microscopy. X-ray diffraction shows the kaolinite to be highly ordered with a Hinekley index of 1.42 and intercalated to ~90%. X-ray diffraction also showed that the intercalated kaolinite was deintercalated by 80% in the first minute of washing. An additional Raman band, attributed to the inner surface hydroxyl groups, strongly hydrogen bound to the acetate, is observed at 3605 cm-1 for the potassium acetate intercalate with the concomitant loss of intensity in the bands at 3652, 3670, 3684 and 3693 cm-1. Upon deintercalation, the intensity of the 3605 cm-1 band decreased as the 3695 cm-1 band increased. The Raman spectral changes brought about upon deintercalation mirrored the changes observed by X-ray diffraction. Deintercalation of kaolinite caused disordering of the kaolinite.

The mineral conichalcite from the western part of Bagdad mine, Bagdad, Eureka District, Yavapai County, Arizona, USA has been characterized by electronic, near-infrared (NIR), Raman and infrared (IR) spectroscopy. Scanning electron microscopy (SEM) images show that the mineral consists of bundles of fibres. Calculations based on the results of the energy dispersive X-ray analyses on a stoichiometric basis show the substitution of arsenate by 12 wt.% of phosphate in the mineral. Raman and IR bands are assigned in terms of the fundamental modes of AsO43− and PO43− molecules and are related to the mineral structure. Near-IR reflectance spectroscopy shows the presence of adsorbed water and hydroxyl units in the mineral. The Cu(II) coordination polyhedron in conichalcite can have at best pseudo-tetragonal geometry. The crystal field and tetragonal field parameters of the Cu(II) complex were calculated and found to agree well with the values reported for known tetragonal distortion octahedral complexes.

Two mixites from Boss Tweed Mine, Tintic District, Juab County, Utah and Tin Stope, Majuba Hill, Pershing County, Nevada, USA, were analysed by scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and by Raman spectroscopy. The SEM images show the mixite crystals to be elongated fibres up to 200 μm long and 2 μm wide. Detailed images of the mixite crystals show the mineral to be composed of bundles of fibres. The EDX analyses depend on the crystal studied, though the Majuba mixite gave analyses which matched the formula BiCu6(AsO4)3(OH)6.3H2O. Raman bands observed in the 880–910 cm−1 and 867–870 cm−1 regions are assigned to the AsO-stretching vibrations of (HAsO4)2− and (H2AsO4)− units, whilst bands at 803 and 833 cm−1 are assigned to the stretching vibrations of uncomplexed (AsO4)3- units. Intense bands observed at 473.7 and 475.4 cm−1 are assigned to the v4 bending mode of AsO4 units. Bands observed at 386.5, 395.3 and 423.1 cm−1 are assigned to the v2 bending modes of the HAsO4 (434 and 400 cm−1) and the AsO4 groups (324 cm−1). Raman spectroscopy lends itself to the identification of minerals on host matrices and is especially useful for the identification of mixites.

The application of Raman spectroscopy to the study of the mixed cationic Pb-Cu and Pb-Cu-Ag minerals: boleite, cumengeite and diaboleite has enabled their molecular structures to be compared. Each of these three minerals shows different hydroxyl-stretching vibrational patterns, but some similarity exists in the Raman spectra of the hydroxyl-deformation modes. The low-wavenumber region is characterized by the bands assigned to the cation-chloride stretching and bending modes. Phosgenite is also a mixed chloride-carbonate mineral and a comparison is made with the molecular structure of the aforementioned minerals. Raman spectroscopy lends itself to the study of these types of minerals in complex mineral systems of secondary mineral formation.

The molecular structure of the three vivianite-structure, compositionally related phosphate minerals vivianite, baricite and bobierrite of formula M32+(PO4)2.8H2O where M is Fe or Mg, has been assessed using a combination of Raman and infrared (IR) spectroscopy. The Raman spectra of the hydroxyl-stretching region are complex with overlapping broad bands. Hydroxyl stretching vibrations are identified at 3460, 3281, 3104 and 3012 cm−1 for vivianite. The high wavenumber band is attributed to the presence of FeOH groups. This complexity is reflected in the water HOH-bending modes where a strong IR band centred around 1660 cm−1 is found. Such a band reflects the strong hydrogen bonding of the water molecules to the phosphate anions in adjacent layers. Spectra show three distinct OH-bending bands fromstrongly hydrogen-bonded, weakly hydrogen bonded water and non-hydrogen bonded water. The Raman phosphate PO-stretching region shows strong similarity between the three minerals. In the IR spectra, complexity exists with multiple antisymmetric stretching vibrations observed, due to the reduced tetrahedral symmetry. This loss of degeneracy is also reflected in the bending modes. Strong IR bands around 800 cm−1 are attributed to water librational modes. The spectra of the three minerals display similarities due to their compositions and crystal structures, but sufficient subtle differences exist for the spectra to be useful in distinguishing the species.

The Raman spectrum of holmquistite, a Li-containing orthorhombic amphibole from Bessemer City, USA has been measured. The OH-stretching region is characterized by bands at 3661, 3646, 3634 and 3614 cm−1 assigned to 3 Mg–OH, 2 Mg + Fe2+–OH, Mg + 2Fe2+–OH and 3 Fe2+–OH, respectively. These Mg and Fe2+ cations are located at the M1 and M3 sites and have a Fe2+/(Fe2+ + Mg) ratio of 0.35. The 960–1110 cm−1 region represents the antisymmetric Si–O–Si and O–Si–O stretching vibrations. For holmquistite, strong bands are observed around 1022 and 1085 cm−1 with a shoulder at 1127 cm−1 and minor bands at 1045 and 1102 cm−1. In the region 650–800 cm−1 bands are observed at 679, 753 and 791 cm−1 with a minor band around 694 cm−1 attributed to the symmetrical Si–O–Si and Si–O vibrations. The region below 625 cm−1 is characterized by 14 vibrations related to the deformation modes of the silicate double chain and vibrations involving Mg, Fe, Al and Li in the various M sites. The 502 cm−1 band is a Li–O deformation mode while the 456, 551 and 565 cm−1 bands are Al–O deformation modes.

A practical application of two-dimensional subsonic bluff body flow research can be seen in the design, construction and positioning of tall slender buildings. Similarly, from a three-dimensional viewpoint, drag reduction and vortex control is an important factor in the latest road vehicle designs. From just these two examples it can be seen that the problem of flow about a bluff body is one of major practical importance, while at the same time being of great theoretical interest. However, despite many years of extensive testing, there has been little progress made on the theoretical investigation of turbulent base flows since the foundations laid down by Kirchhoff and von Karman. The non-steady processes in the wake, in particular the complex dynamics of vortex formation, have proved to be problems of formidable size.

Understanding the nutritional demands on serving military personnel is critical to inform training schedules and dietary provision. Troops deployed to Afghanistan face austere living and working environments. Observations from the military and those reported in the British and US media indicated possible physical degradation of personnel deployed to Afghanistan. Therefore, the present study aimed to investigate the changes in body composition and nutritional status of military personnel deployed to Afghanistan and how these were related to physical fitness. In a cohort of British Royal Marines (n 249) deployed to Afghanistan for 6 months, body size and body composition were estimated from body mass, height, girth and skinfold measurements. Energy intake (EI) was estimated from food diaries and energy expenditure measured using the doubly labelled water method in a representative subgroup. Strength and aerobic fitness were assessed. The mean body mass of volunteers decreased over the first half of the deployment ( − 4·6 (sd 3·7) %), predominately reflecting fat loss. Body mass partially recovered (mean +2·2 (sd 2·9) %) between the mid- and post-deployment periods (P< 0·05). Daily EI (mean 10 590 (sd 3339) kJ) was significantly lower than the estimated daily energy expenditure (mean 15 167 (sd 1883) kJ) measured in a subgroup of volunteers. However, despite the body mass loss, aerobic fitness and strength were well maintained. Nutritional provision for British military personnel in Afghanistan appeared sufficient to maintain physical capability and micronutrient status, but providing appropriate nutrition in harsh operational environments must remain a priority.