Early Stage Of Deposition Research Articles

Surface–texture evolution of different chemical-vapor-deposited zinc sulfide flats polished with various magnetorheological fluids

The macro-structure of chemical-vapor-deposited (CVD) zinc sulfide (ZnS) substrates is characterized by cone-like structures that start growing at the early stages of deposition. As deposition progresses, these cones grow larger and reach centimeter size in height and millimeter size in width. It is challenging to polish out these features from the top layer, particularly for the magnetorheological finishing (MRF) process. A conventional MR fluid tends to leave submillimeter surface artifacts on the finished surface, which is a direct result of the cone-like structure.Here we describe the MRF process of polishing four CVD ZnS substrates, manufactured by four different vendors, with conventional MR fluid at pH 10 and zirconia-coated-CI (carbonyl iron) MR fluids at pH 4, 5, and 6. We report on the surface–texture evolution of the substrates as they were MRF polished with the different fluids. We show that performances of the zirconia-coated-CI MR fluid at pH 4 are significantly higher than that of the same fluid at pH levels of 5 and 6 and moderately higher than that of a conventional MR fluid at pH 10. An improvement in surface–texture variability from part to part was also observed with the pH 4 MR fluid.

Atomic Layer Deposition of Hafnium(IV) Oxide on Graphene Oxide: Probing Interfacial Chemistry and Nucleation by using X-ray Absorption and Photoelectron Spectroscopies.

Interfacing graphene with metal oxides is of considerable technological importance for modulating carrier density through electrostatic gating as well as for the design of earth-abundant electrocatalysts. Herein, we probe the early stages of the atomic layer deposition (ALD) of HfO2 on graphene oxide using a combination of C and O K-edge near-edge X-ray absorption fine structure spectroscopies and X-ray photoelectron spectroscopy. Dosing with water is observed to promote defunctionalization of graphene oxide as a result of the reaction between water and hydroxyl/epoxide species, which yields carbonyl groups that further react with migratory epoxide species to release CO2 . The carboxylates formed by the reaction of carbonyl and epoxide species facilitate binding of Hf precursors to graphene oxide surfaces. The ALD process is accompanied by recovery of the π-conjugated framework of graphene. The delineation of binding modes provides a means to rationally assemble 2D heterostructures.

Band-gap and sub-band-gap photoelectrochemical processes at nanocrystalline CdS grown on ZnO by successive ionic layer adsorption and reaction method

Cadmium sulfide nanoparticle (NP) deposition by the successive ionic layer adsorption and reaction (SILAR) method on the surface of mesoporous ZnO micro-platelets with a large specific surface area (110±10m2g−1) results in the formation of ZnO/CdS heterostructures exhibiting a high incident photon-to-current conversion efficiency (Y) not only within the region of CdS fundamental absorption (Ymax=90%; 0.1M Na2S+0.1M Na2SO3), but also in the sub-band-gap (SBG) range (Ymax=25%). The onset potentials of SBG photoelectrochemical processes are more positive than the band-gap (BG) onset potential by up to 100mV. A maximum incident photon-to-current conversion efficiency value for SBG processes is observed at larger amount of deposited CdS in comparison with the case of BG ones. The Urbach energy (EU) of CdS NPs determined from the photocurrent spectra reaches a maximal value on an early deposition stage (EU=93mV at SILAR cycle number N=5), then lowers somewhat (EU=73mV at N=10) and remains steady in the range of N from 20 to 300 (EU=67±1mV). High efficiency of the photoelectrochemical SBG processes are interpreted in terms of light scattering in the ZnO/CdS heterostructures.

In Situ Localized Surface Plasmon Resonance (LSPR) Spectroscopy to Investigate Kinetics of Chemical Bath Deposition of CdS Thin Films

Techniques that can characterize the early stages of thin film deposition from liquid phase processes can aid greatly in our understanding of mechanistic aspects of chemical bath deposition (CBD). Here we have used localized surface plasmon resonance (LSPR) spectroscopy to monitor the in situ kinetics of early stage growth of cadmium sulfide (CdS) thin films on Ag nanoparticle on quartz substrates. Real-time shift during CdS deposition showed that the LSPR wavelength red-shifted rapidly due to random deposition of CdS on the substrate but saturated at longer times. LSPR modeling showed that these features could be interpreted as an initial deposition of CdS islands followed by preferential deposition onto itself. The CdS also showed significantly enhanced Raman signals up to 170 times due to surface-enhanced Raman scattering (SERS) from the CdS/Ag NP regions. The ex situ SERS effect supported the LSPR shift, suggesting that these techniques could be used to understand nucleation and growth phenomena from ...

MOCVD에 의한 Al 박막 증착 중의 표면 반사도 측정을 통한 박막 성장 메커니즘 분석

Al thin films were deposited on TiN/Si(100) via metal-organic chemical vapor deposition using N-methylpyrrolidine alane as a precursor. Characterization of the deposited films were investigated with SEM, XRD, -step, AFM, 4-point probe. The early stage of Al thin film deposition was analyzed by in-situ surface reflectance measurement with laser and photometer apparatus. The surface reflectance were changed greatly during the initial 30~40 seconds. There were two increases and two decreases in the surface reflectance, thus the sequence of Al films were deposited at 8 significant points of the surface reflectance change. Surface topograph and cross-sectional view of each film were analyzed with SEM. Al films were grown in the complex mechanism of Volmer-Weber and Stranski-Krastanov process.

Elemental and mineralogical anomalies in the coal-hosted Ge ore deposit of Lincang, Yunnan, southwestern China: Key role of N2–CO2-mixed hydrothermal solutions

The Lincang Neogene high-Ge coal deposit in Yunnan, southwestern China, is one of the major coal-hosted Ge deposits in the world. This study reports new data on the petrological, mineralogical, and geochemical compositions of 57 samples (including coal bench samples, roofs, floors, partings, and batholith granite) of three high-Ge coal seams (S3, Z2, and X1) from the Dazhai Mine, Lincang Ge ore deposit, and provides new insights into the origin and modes of occurrence of the minerals and elements present.The coals have huminite random reflectances in the 0.33–0.48% range. On a mineral-free basis, the coal samples are dominated by huminite-group macerals, all having more than 88.5% total huminite. Ulminite and attrinite generally dominate the huminite macerals. Structured inertinite is rare, with funginite being the most abundant inertinite form. The minerals in the coals are mainly composed of quartz, and, to a lesser extent, kaolinite, illite, and mica. A hydrous beryllium sulfate phase (BeSO4·4H2O) is present in the low temperature ashes of several coal samples.Compared to average values for world low-rank coals, beryllium (up to 2000μg/g and 343μg/g on average), Ge (up to 2176μg/g and 1590μg/g on average), and W (up to 339μg/g and 170μg/g on average) are unusually enriched in the Lincang coals, with a concentration coefficient >100 (CC=ratio of element concentration in investigated coals vs. world low-rank coals); elements As (156μg/g on average), Sb (38μg/g), Cs (25.2μg/g), and U (52.5μg/g) are significantly enriched (10<CC<100); niobium (28.2μg/g) is enriched (CC=8.55); zinc, Rb, Y, Cd, Sn, Er, Yb, Lu, Hg, Tl, and Pb are slightly enriched (2<CC<5).The biotite- and two-mica granites, which served as both the basement for the coal-bearing sequence and as a source of sediment input, were also either hydrothermally-altered or -argillized. The alteration appears to have taken place during or shortly after deposition of the coal-bearing sequence. Two types of metasomatites of hydrothermal origin, including quartz–carbonate and carbonate, were identified, which occur as partings and as roof and floor strata. These metasomatites were formed at the syngenetic or early diagenetic stages of coal deposition. The rare earth elements in these hydrothermal rocks are characterized by a heavy REE enrichment type and by distinct positive Eu anomalies, compared to the upper continental crust.Hydrothermal solutions have played a significant role in producing the elemental and mineralogical anomalies in the Lincang Ge ore deposit. The hydrothermal solutions leaching the batholith granite were a mixture of alkaline N2-bearing and volcanogenic CO2-bearing fluids, which led to the enrichment of trace elements, not only including assemblages of Ge–W and Be–Nb–U (both leached from granite and the deposited in the peat), but also As–Sb (from volcanogenic solution), as well as the alteration and argillization of the batholith granites, and the formation of carbonate and quartz–carbonate metasomatites.

An in situ XPS study of growth of ITO on amorphous hydrogenated Si: Initial stages of heterojunction formation upon processing of ITO/a-Si:H based solar cell structures

In this work we studied the interface growth upon deposition of indium-tin oxide (ITO) on amorphous hydrogenated Si (a-Si:H)/crystalline Si (c-Si) structures. The analysis methods used were X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) in combination with in situ film growth with magnetron sputtering. The analysis was complemented with transmission electron microscopy (TEM) of the deposited films. The sputtering equipment was attached to the XPS spectrometer and hence early stage film growth was observed without breaking the vacuum. It was shown that during early deposition stages ITO is reduced by a-Si:H. The reduction is accompanied with formation of metallic In and Sn at the interface. Formation of Sn is more enhanced on a-Si substrates whilst formation of In is more dominant on c-Si substrates. The reduction effect is less intense for amorphous hydrogenated Si as compared to crystalline Si and this is attributed to stronger presence of dangling bonds in the latter than the former.

Erratum to: “Electronic properties of ultrathin films based on pyrrolofullerene molecules on the surface of oxidized silicon”

Results of the investigation into the interface formation during the deposition of the films based on aziridinylphenylpyrrolofullerene (APP-C60) up to 8 nm thick on the surface of the oxidized silicon substrate are presented. The procedure of detecting reflection of testing low-energy electron beam from the surface implemented in the total current spectroscopy mode with a change in the incident electron energy from 0 to 25 eV is used. The structure of maxima in the total current spectra induced by the APP-C60 deposited film is established, and the character of interrelation of these maxima with π* and σ* energy bands in the studied materials is determined. It is revealed due to analyzing the variation in intensities of the total current spectra of the deposited APP-C60 film and the (SiO2)n-Si substrate that the APP-C60 film is formed at the early deposition stage with the coating thickness thinner than one monolayer without the formation of the intermediate modified organic layer. As the APP-C60/(SiO2)n-Si interface is formed, the work function of the surface increases by 0.7 eV, which corresponds to the transfer of the electron density from substrate (SiO2)n-Si toward the film APP-C60. The optical absorption spectra of the APP-C60 films are measured and compared with the spectra of films of unsubstituted C60.

In situ X-ray diffraction analysis of the onset of mineral scale deposition from synthetic oilfield processing waters

The deposition of barite (BaSO4) scale on stainless steel has been investigated using in situ X-ray diffraction. Scale build-up in oilfield processing lines costs the industry millions of dollars per annum in lost production and maintenance, and improved strategies to combat scale build-up through greater understanding of the very early stage of scale deposition would be of significant benefit. Here, through the acquisition of very rapid diffraction datasets during scale deposition from the mixing of synthetic sea and formation waters, the barite growth curve – characterised by very rapid scale deposition during the period 0⩽t⩽105s before a regime of more gradual linear growth in the range 105⩽t⩽450s – was determined. In addition, during the period of rapid deposition the scale was found to exhibit significant preferred orientation along the (020) axis, which became less significant as deposition continued. Diffraction is the only technique which provides direct and simultaneous information about mineralogy and crystallographic orientation, and its implementation here to characterise the onset of barite scale formation is a significant advance in the analytical capabilities at the disposal of engineers to investigate scale formation in an oil and gas processing context.

In Situ Stress Measurements Using Cantilever Curvature

The electrodeposition community has been very active in the development of in situ stress measurements during electrochemical processing. The simplest and most widely used methods involve the measurement of the deflection of a flexible cathode, typically in a direction that is perpendicular to the in-plane stress generated in the film. These in situ stress measurements have been used to examine adsorbate-induced surface stress, underpotential deposition, electrochemical intercalation reactions, and bulk film deposition.Intrinsic stress is caused by the manner in which the film grows and can arise from lattice-mismatched epitaxial growth, nuclei coalescence and grain growth during deposition, and other processes that occur during thickening of the continuous film. For example, Cu grows on Au by a Stranski–Krastanov mechanism where island coalescence is the primary source of stress generation. Figure 1 shows the average in-plane stress associated with the bulk deposition of copper from an additive-free sulfate electrolyte. The large tensile stress generated in the early stages of deposition is consistent with nuclei coalescence and subsequent grain boundary formation. As the deposit thickens, the average film stress decreases rather quickly and even becomes compressive in deposits formed at small deposition overpotentials. If deposition is interrupted in this compressive stage (Fig. 1 inset), a rapid relaxation of the stress occurs. When deposition is resumed the stress level is re-established as if the interruption had never occurred. This behavior is consistent with compressive stress generation due to the reversible diffusion of ad-atoms on the surface into grain boundaries.Electrochemical impedance spectroscopy (EIS) is often used to separate electrochemical processes with different characteristic time constants. A sinusoidal voltage (typically of the order of a few mV) is applied to an electrochemical system and the current response is measured. The frequency of the applied voltage is varied so that different processes can be singled out at specific frequencies. Dynamic stress analysis (DSA) is analogous to EIS, however in addition to the current, the cantilever’s curvature is also measured as a function of frequency. The aim of DSA is to study the dynamics of any particular stress-generating process and link the stress to specific electrochemical and surface phenomena. We have demonstrated the technique by examining the electrocapillarity (charge-induced stress) of both Pt and Au in HClO4 electrolyte.1 In this case the figure of merit is the stress charge coefficient (ξ) which captures the fundamental surface mechanics associated with charging the electrode surface. As expected for capacitive charging, there is no frequency dependence (below the resonant frequency of the cantilever). In this paper we apply DSA to the electrodeposition of Cu, our first attempt to add a stress-generating faradaic reaction to the electrocapillarity response. DSA should be sensitive to not only the stress generating mechanisms that contribute to the steady-state stress but to relaxation processes that may occur as well.1. (a) Lafouresse, M. C.; Bertocci, U.; Beauchamp, C. R.; Stafford, G. R., Simultaneous Electrochemical and Mechanical Impedance Spectroscopy Using Cantilever Curvature. J. Electrochem. Soc. 2012, 159, H816; (b) Lafouresse, M. C.; Bertocci, U.; Stafford, G. R., Dynamic Stress Analysis Applied to (111)-Textured Pt in HClO4 Electrolyte. J. Electrochem. Soc. 2013, 160, H636.

Kinetics of second layer nucleation with permeable steps

The critical island size for second layer nucleation is a basic parameter which determines the mechanism of growth and in turn the morphology of the growing surface. When it is larger than the mean distance between the islands layer-by-layer growth takes place. In the opposite case 3D mounds are formed. The critical island size for second layer nucleation is calculated by taking into account the ability of adatoms to cross the step surrounding the island without joining the kink sites (the effect of the step permeability). We have found that the mean field approximation fails to give solution in the case of permeable steps. By making use of the probabilistic approach for derivation of the nucleation frequency on top of the first layer island we show that the critical size decreases with increasing degree of permeability. This is due to the contribution of atoms from the area surrounding the island which is especially important at the early stage of deposition where the average size of the first layer islands is small. The decrease of the critical size is steeper at higher temperatures or smaller densities of the first layer nuclei and in turn larger areas around the islands which feed the latter. The rate of growth of the first level island remains unaffected by the step permeability as the adatoms always join the step after several (or many) attempts under the condition of complete condensation. An important conclusion is that the step permeability could give rise to a transition from planar to 3D growth.

Osteogenic differentiation of placenta-derived multipotent cells in vitro

ObjectiveStem cells offer great potential for clinical therapeutic use because of their ability to rejuvenate and to differentiate into numerous types of cells. We isolated multipotent cells from the human term placenta that were capable of differentiation into cells of all three germ layers. Materials and methodsWe examined the ability of these placenta-derived multipotent cells (PDMCs) to differentiate into osteoblasts (OBs) or OB-like cells. The PDMCs were treated with osteogenic medium (OM) consisting of dexamethasone, β-glycerol phosphate, and ascorbic acid. At sequential time intervals (0 day, 3 days, 6 days, 9 days, and 12 days) we measured several parameters. These included alkaline phosphatase (ALP) activity, alizarin red staining (ARS) to measure calcium deposition, messenger RNA (mRNA) expressions of osteogenesis-related transcription factor (Cbfa1), and calcium coordination protein (osteocalcin). These variables were used as indicators of PDMC osteodifferentiation. ResultsWe showed that ALP activity in the early stage of differentiation and calcium deposition were both significantly increased in PDMCs after OM induction. Moreover, the Cbfa1 and osteocalcin gene expressions were upregulated. The results suggested that OM induced an osteodifferentiation potential in PDMCs. ConclusionPDMC-derived osteocytes provide a useful model to evaluate the mechanisms of key biomolecules and bioengineering processes.

Transmission electron microscopy on early-stage tin oxide film morphology grown by atmospheric pressure chemical vapor deposition

Nucleation and morphology development during the early stages of chemical vapor deposition (CVD) processes are believed to be of major importance for the overall film properties. Here, the authors have investigated the nucleation of tin oxide films, comparing different tin precursors (tin tetrachloride (TTC) and monobutyl tin trichloride (MBTC)) and focusing on the effect of methanol addition on the film morphology. Employing electron transparent silicon oxide membranes as substrates and combining transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis on the same set of samples, we describe a detailed picture of nucleation behavior and film growth during early stages of film formation. Our main conclusion is that methanol addition during deposition acts as surfactant, lowering the surface energy of the substrate and resulting in a higher nucleation grain density. Based on these results, we propose a film growth model based on surface energy to explain morphology differences in tin oxide films resulting from methanol addition. cop. 2014 Elsevier B.V.

철강 위에 SiC 중간층을 사용한 나노결정질 다이아몬드 코팅

Nanocrystalline diamond(NCD) films on steel(SKH51) has been investigated using SiC interlayer film. SiC was deposited on SKH51 or Si wafer by RF magnetron sputter. NCD was deposited on SiC at <TEX>$600^{\circ}C$</TEX> for 0.5~4 h employing microwave plasma CVD. Film morphology was observed by FESEM and FIB. Film adherence was examined by Rockwell C adhesion test. The growth rate of NCD on SiC/Si substrate was much higher than that on SiC/SKH51. During particle coalescence, NCD growth rate was slow since overall rate was determined by the diffusion of carbon on SiC surface. After completion of particle coalescence, NCD growth became faster with the reaction of carbon on NCD film controlling the whole process. In the case of SiC/SKH51 substrate, a complete NCD film was not formed even after 4 h of deposition. The adhesion test of NCD/SiC/SKH51 samples revealed a delamination of film whereas that of SiC/SKH51 showed a good adhesion. Many voids of less than 0.1 <TEX>${\mu}m$</TEX> were detected on NCD/SiC interface. These voids were believed as the reason for the poor adhesion between NCD and SiC films. The origin of voids was due to the insufficient coalescence of diamond particles on SiC surface in the early stage of deposition.

Self-assembled folding of a biaxially compressed film on a compliant substrate

Amorphous carbon films grown by ion beam deposition from hydrocarbon precursors on compliant polymer substrates are shown here to undergo spontaneous self-assembled folding during growth. When deposited up to 30min, the deposition-induced stretch strain of an amorphous carbon film on poly(dimethylsiloxane) (PDMS) with a Young’s modulus of 1–2MPa reached more than 50%, which is much higher than usually observed compressive mismatch strains of approximately 1–2% on silicon. During deposition of the carbon film, compliant PDMS substrates allowed large amplitude film buckling to let in lateral growth of the film with the significant compressive mismatch strain. The film wrinkled at a low strain of approximately 1% at an early stage of deposition. Then, the wrinkled film was observed to transform its configuration through two different nonlinear modes; formations of ridges and asymmetric localized folds. Due to the biaxial nature of the deposited thin film, the wrinkled film showed herringbone or labyrinth patterns for strains less than 10%, while the folds were made in random orientations to create asymmetric disordered tessellation for strains more than 30%.

Evidence from molybdenum and iron isotopes and molybdenum–uranium covariation for sulphidic bottom waters during Eastern Mediterranean sapropel S1 formation

Redox exerts a critical control on organic carbon-rich sedimentation. This is particularly true for Eastern Mediterranean sapropels where seawater stratification is regarded as a major driving force for oxygen depletion, but in which sulphidic (euxinic) bottom waters occur only sporadically. Here we apply a powerful array of geochemical proxies (Fe and Mo stable isotopes together with Mo/U ratios and redox sensitive trace elements (RSTE)) to the determination of water redox evolution during the deposition of Holocene S1 sapropel and its underlying and overlying sediments (ODP core 967D; 2550 m depth).RSTE are asymmetrically distributed within the sapropel, with peak enrichments occurring in its lower (early) part. Negative correlations are found between δFe57 and both Fe/Al and S wt% in the lower sapropel, and are consistent with the benthic Fe shuttle model Fe enrichment in euxinic basins. MoEF/UEF enrichment factor variations show well defined trends identical to those proposed for open marine settings, in which sub-oxic conditions in the background sediments give way to sulphidic waters at the RSTE peak in the lower sapropel. The most notable features of the Mo isotope profile are ‘atypically’ light values (δMo98/95<−0.7‰) in the lower sapropel. Such light Mo isotope values (relative to sea water δMo98/95=2.3‰) have been related to oxic remobilisation. However, negative correlations between δMo98/95 and Fe/Al, Ba/Al, Mo/Al and S imply that the lowest Mo isotopic compositions are associated with peak reducing conditions. Taken in conjunction with the evidence from the other proxies for a sulphidic water column, the light Mo isotope values in the lower sapropel are best explained by a large isotopic fractionation between sea water molybdate and thiomolybdate species in mildly euxinic bottom waters ([H2S]aq <10 μM). The data from this study thus show that hitherto unrecognised euxinic conditions occur during the early stages of deposition of the Holocene sapropel S1. Molybdenum isotopes and Ba/Al ratios identify a short-lived sapropel re-ventilation event timed to coincide with the 8.2 ka cold climatic Event.

Settled, symbiotic, then sexually mature: adaptive developmental anatomy in the deep-sea, chemosymbiotic mussel Idas modiolaeformis

The Bathymodiolinae are pervasive in reducing environments in the deep sea, yet data on post-larval and juvenile development and on the process of symbiont acquisition remain elusive. To understand how these opportunistic metazoans survive in ephemeral reducing habitats, individuals of the small bathymodiolin, Idas modiolaeformis, were examined histologically to trace their reproductive development, and with fluorescence and transmission electron microscopy to identify patterns of infection by their environmentally acquired bacterial symbionts. A size series of these mussels was retrieved from larval colonisation devices containing vegetative substrates, deployed for 51 weeks (November 2006–2007) in the central ‘Pockmarks’ region (site 2A) of the Nile deep-sea fan in the eastern Mediterranean (NDSF), a zone where methane seepage can occur (N 32° 31.97, E 30° 21.18, 1,693 m deep). Developmental patterns of germ cell migration, size at first maturity, and symbiont acquisition and localisation are presented for the post-larva to adult transition. The smallest mature adult was a male with shell length (SL) 2.35 mm. All larger individuals in the series were male (maximum SL 6.54 mm). Based on the absence of bacterial signals, plantigrades were asymbiotic, indicating strict heterotrophy in larvae and early post-larvae. During the early stages of dissoconch deposition, extracellular symbiont infection was non-specific. This was followed by increasing specificity on non-ciliated gill epithelia in adults. These observations on early development in I. modiolaeformis represent evolutionary adaptations to their ephemeral, reducing habitats.

The growth of cobalt oxides on HOPG and SiO2 surfaces: A comparative study

The growth of cobalt oxides by reactive thermal evaporation of metallic cobalt on highly oriented pyrolytic graphite (HOPG) and SiO2 (X cut quartz surface), in an oxygen atmosphere at room temperature, has been chemically and morphologically studied by means of X-ray photoelectron spectroscopy and atomic force microscopy. The chemical analysis, which also includes cluster calculations, reveals that for the early deposition stages on both substrates, Co2+ species are stabilized at the surface up to a coverage which depends on the substrate. Further coverages lead to the formation of the spinel oxide Co3O4. The results are discussed in terms of the dependence of the surface energy on the size of the CoO deposited moieties. On the other hand, it has been found that the initial way of growth of cobalt oxides on HOPG is of Stranski–Krastanov mode whereas on SiO2 the growth is of Volmer–Weber mode. The differences in the growth morphology have been discussed in terms of the surface diffusivity of the CoO deposits on the substrates.

A Boron Isotope Study of the Furnace Creek, California, Borate District

About a third of the approximately 30 known deposits in the Furnace Creek, California, borate district reveal mineralogical zoning of borates. The deposits feature an Na-Ca borate (ulexite and/or probertite) inner zone (or zones) surrounded by Ca borate (colemanite). The remaining deposits consist essentially of colemanite. Investigators have debated the origin of the mineralogical zoning and the relationship, if any, between the zoned and colemanite-only deposits. The Ca and Na-Ca borate zoning has been characterized as either primary or formed by postdepositional alteration. Boron isotope analysis was applied to drill core samples from two zoned deposits, one non-zoned deposit, and selected samples from six other deposits accessed from surface and subsurface mine workings. Probertite samples from the inner regions of two zoned deposits yield δ 11B values near 5‰, whereas most colemanite samples from both zoned and non-zoned deposits yield results near −1‰. The small δ 11B range of most of the colemanite samples and their distribution from a grouping near 0‰ to isotopically lighter values suggest a pattern formed by alteration from a common initial value. Based on the new isotopic data and existing sedimentologic and stratigraphic knowledge of the Furnace Creek borate deposits, it is proposed that the isotopically heavier boron of probertite in the inner zone of zoned deposits reflects the composition of the ancestral lake and its springs during an early stage of deposition of the laminated series of the Furnace Creek Formation. Furthermore, the isotopically lighter B of colemanite in zoned deposits reflects the alteration of earlier formed Na-Ca borate deposits by downward migrating lake water at a later stage of deposition of the laminated series. Some non-zoned Ca borate deposits may have been precipitated directly during the later stages.

Simultaneous Raman Microspectroscopy and Fluorescence Imaging of Bone Mineralization in Living Zebrafish Larvae

Confocal Raman microspectroscopy and fluorescence imaging are two well-established methods providing functional insight into the extracellular matrix and into living cells and tissues, respectively, down to single molecule detection. In living tissues, however, cells and extracellular matrix coexist and interact. To acquire information on this cell-matrix interaction, we developed a technique for colocalized, correlative multispectral tissue analysis by implementing high-sensitivity, wide-field fluorescence imaging on a confocal Raman microscope. As a proof of principle, we study early stages of bone formation in the zebrafish (Danio rerio) larvae because the zebrafish has emerged as a model organism to study vertebrate development. The newly formed bones were stained using a calcium fluorescent marker and the maturation process was imaged and chemically characterized in vivo. Results obtained from early stages of mineral deposition in the zebrafish fin bone unequivocally show the presence of hydrogen phosphate containing mineral phases in addition to the carbonated apatite mineral. The approach developed here opens significant opportunities in molecular imaging of metabolic activities, intracellular sensing, and trafficking as well as in vivo exploration of cell-tissue interfaces under (patho-)physiological conditions.