Laser Raman Spectroscopy Research Articles

Evolution of Ore-Forming Fluids and Gold Deposition of the Sanakham Lode Gold Deposit, SW Laos: Constrains from Fluid Inclusions Study

The Sanakham gold deposit is a newly discovered gold deposit in the Luang Prabang (Laos)–Loei (Thailand) metallogenic belt. It consists of a series of auriferous quartz-sulfide veins, which is distinguished from the regional known porphyry-related skarn and epithermal gold deposits. There are four mineralization stages identified in Sanakham, with native gold grains mainly occurring in stages II and III. Evolution of ore-forming fluids and gold deposition mechanisms in Sanakham are discussed based on fluid inclusion petrography, microthermometry, and Laser Raman spectroscopy. The original ore-forming fluids belong to a medium-high temperature (>345 °C) CH4-rich CH4–CO2–NaCl–H2O system. In stages II and III, the ore fluids evolve into a NaCl–H2O–CO2 ± CH4 system characterized by medium temperature (~300 °C), medium salinity (~10 wt% NaCl eq.), and CO2-rich (~10% mol). They might finally evolve into a NaCl–H2O system with temperature decreasing and salinity increasing in stage IV. Two fluid immiscibility processes occurred in stages II and III, which created high-CH4 & low-CO2 and low-CH4 & high-CO2 end-members, and CO2-poor and CO2-rich endmembers, respectively. Gold-deposition events are suggested to be associated with the fluid immiscibility processes, with P–T conditions and depth of 236–65 MPa, 337–272 °C, and 8.7–6.5 km, respectively.

Transformation of a Large Ancient Oil Reservoir to a Dry Gas Reservoir: A Case Study of the Kela-2 Gas Field in the Kuqa Foreland Basin, NW China

Various lines of evidence, including the occurrence of bitumen and fluid inclusions, show that oil charge once took place in the Kela-2 gas field, Kuqa foreland basin, Northwest China. However, the scale of the ancient oil reservoir remains unclear, as does the process by which the reservoir evolved into the present dry gas field. Here, using data from analyses of fluid inclusions, petrography, laser Raman spectroscopy, and quantitative fluorescence, the hydrocarbon accumulation history of the Kela-2 gas field is reconstructed. The results show that the gas field underwent three periods of hydrocarbon charging and one period of adjustment. The first oil charging occurred at about 12 Ma, as recorded by the first group of oil inclusions containing 0–8 vol.% gas with yellowish-brown fluorescence. The second charging involved mature oil charging at about 4 Ma, recorded by the second group of oil inclusions containing 15–25 vol.% gas with blue-white fluorescence. According to quantitative grain fluorescence (QGF) and rock pyrolysis analysis, an ancient oil reservoir existed with an oil-column height of about 350 m, and the paleo oil–water contact was lower than the present gas–water contact. Under intense thrusting from 3 Ma, the ancient oil reservoir was destroyed, with oil escaping through the Kashangtuokai thrust fault, which broke the salt layer, as this layer at that time lay in the brittle deformation domain. The inferred destruction of the ancient oil reservoir is supported by the numerous oil and gas shows at the surface and in shallow layers near the Kashangtuokai fault, as well as the anomalous development of authigenic kaolinite in the gas reservoir, which was enhanced by an open or semiopen system caused by the fault breaking through the salt layer. Subsequently, with increasing burial depth to more than 3000 m, the fault that had cut through the salt layer annealed because the salt layer then lay within the ductile deformation domain. The higher overpressure that occurred during the third gas charging at about 2 Ma reflected the annealing of the fault in the salt layer, favoring late gas accumulation and preservation. The evolution of the Kela-2 gas field provides an important case study for understanding the role of the salt layer crossing the brittle–plastic transition and the dynamic evolution of the salt caprock in salt-containing foreland basins.

Optimal condition for fabricating mechanically durable superhydrophobic titanium surface by rapid breakdown anodization: Self cleaning and bouncing characteristics

In this paper, we describe a simple, cost effective, fast, scalable and sustainable method for fabrication of mechanically durable superhydrophobic (SHP) surface of titanium by a rapid breakdown anodization (RBA) followed by molten stearic acid (MSA) chemical modification. In this new approach, the preparation time is only a minute. Instead of stearic acid- ethanol solution, molten stearic acid is the post surface modification, which made the preparation process rapid and simple. The anodized samples showed islands of TiO2 microclusters with complex hierarchical structures with nano pores uniformly distributed in the passive TiO2 matrix. Laser Raman spectroscopy (LRS) analysis revealed the TiO2 microclusters are polycrystalline in nature. The applied voltage, anodization time, immersion time and MSA bath temperature are optimized to obtain a robust mechanically durable SHP surface. FESEM images showed that both anodization and immersion parameters have significant effect on the surface morphology of microclusters. A maximum water contact angle (WCA) of 167.8° with a sliding angle of 6° was obtained for a Ti sample anodized at 50 V for 10 min after molten stearic acid immersion at 125 °C for 30 min. The prolonged anodization for 10 min promoted microcluster growth in all dimensions to form a highly hierarchical micro-nanostructure. The prepared samples showed vertical micro plate-like crystals of stearic acid on the micro clusters, which enhanced the very high WCA. The FTIR results revealed multiple bonding modes of stearic acid with TiO2 microclusters through surface hydroxyl groups. The prepared superhydrophobic samples showed excellent self-cleaning and abrasion resistance.

Study on friction properties of polydopamine modified graphene oxide as lubricant additive

In this study, polydopamine-modified graphene oxide (PGO) nanomaterials were prepared based on the self-polymerization of dopamine in a weakly alkaline environment. In the friction experiment, the lubricants with 0.15 wt% PGO nanomaterials have optimal friction properties. Subsequently, X-ray photoelectron spectroscopy (XPS), X-ray energy spectroscopy (EDS), and laser Raman spectroscopy were performed on the wear scar. Compared to pure oil, the friction coefficient was reduced by 31%, and the trace width was reduced by 47.69%. In addition, molecular dynamics simulations showed that PGO has the lowest diffusion coefficient among n-hexadecane and the interaction energy between PGO and n-hexadecane molecules was the largest, and oil droplets containing PGO exhibited the best adsorption performance on the surface of the Si3N4/GCr15. The results showed that compared with other additives, PGO as a lubricant additive can play a significant role in reducing friction and anti-wear.

Degradation of Incoloy‐800HT in molten FLiNaK salt at high temperatures

AbstractMany studies have revealed that Hastelloy‐N is the most suitable material for molten FLiNaK salt application. However, due to the nonavailability and high cost of Hastelloy‐N, Incoloy‐800HT is being considered as an alternate material. Corrosion studies were carried out on Incoloy‐800HT in vacuum‐dried molten FLiNaK salt at 650°C and 750°C for 100, 250, 500 and 1000 h. The exposed specimens were examined for weight loss and subjected to surface analysis using techniques like metallography, confocal laser scanning microscopy, X‐ray diffraction and laser Raman spectroscopy. The results revealed that the weight loss and depth of attack are less in specimens exposed to 650°C than those exposed to 750°C, and there is no evidence of any localised attack at both the temperatures. Chemical analysis of the used salt showed higher Cr and Fe contents than that in fresh salt, indicating dealloying of elements like Cr and Fe from Incoloy‐800HT specimens during exposure to molten FLiNaK salt. Oxides rich in Fe and Cr with spinel‐type crystal structures were identified on the exposed surfaces. From the results, it could be concluded that though there was considerable corrosion of Incoloy‐800HT, the material may be used in static molten FLiNaK salt systems with limited design life restricted to a temperature of 650°C by giving appropriate corrosion allowance.

Chemical Vapor Deposition and Thermal Oxidation of Cuprous Phosphide Nanofilm

Inorganic semiconductors usually show n-type characterization; the development of p-type inorganic semiconductor material will provide more opportunities for novel devices. In this paper, we investigated the chemical vapor deposition (CVD) of p-type cuprous phosphide (Cu3P) nanofilm and studied its thermal oxidation behavior. Cu3P film was characterized by optical microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), laser Raman spectroscopy (Raman), and fluorescence spectroscopy (PL). We found that the thickness of film ranged from 4 to 10 nm, and the film is unstable at temperatures higher than room temperature in air. We provide a way to prepare inorganic phosphide nanofilms. In addition, the possible thermal oxidation should be taken into consideration for practical application.

Imaging and measuring the electronic properties of epitaxial graphene with a photoemission electron microscope

A photoemission electron microscope (PEEM) was recently commissioned at the NIST. To benchmark its capabilities, epitaxial graphene on 4H-SiC (0001) was imaged and analyzed in the PEEM and compared to other complementary imaging techniques. We determine our routine spatial resolution to be about 50 nm. Using the well-known electronic structure of graphene as a reference, we outline a procedure to calibrate our instrument in energy and momenta in the micrometer-angle-resolved photoemission spectroscopy (μ-ARPES). We also determine the energy and momenta resolution to be about 300 meV, 0.08 Å−1 (ky), and 0.2 Å−1 (kx), respectively. We identify distinct regions of the graphene surface based on intensity contrast rising from topographic and electronic contrasts as well as μ-ARPES. These regions are one layer graphene, one SiC buffer layer, and ≥2 layers of graphene (or graphite). These assignments are confirmed using confocal laser scanning microscopy and Raman spectroscopy. Finally, the PEEM instrument had enough sensitivity to observe the flatband in monolayer epitaxial graphene, which we attribute to the presence of compressive strain, −1.2%, in the graphene sample.

Эффективный метод полного контроля процессов производства поли--олефиновых масел — лазерная спектроскопия комбинационного рассеяния

The developed approaches to increasing the selectivity of analysis by laser Raman spectroscopy, the use of chemometrics and a proprietary algorithm for self-tuning calibration models with the efficiency and speed of the method have shown a rare andexcellent opportunity for information equivalent on-line control of all technological stages of the production of poly- -olefin oils and other products through a network of fiber-optic probes. The oligomers of -olefins C6, C8 and C10 obtained by the technology of heterogeneous chromium-oxide catalysis developed at RN-RDC, as shown by the Raman spectra, differ from analogues obtained by homogeneous synthesis by a variety of structures of unsaturated groups, as well as by a greater width and variability of molecular mass distribution, which makes it possible to regulate a wide range assortment of low and high molecular weight products. A specialcase - the atypically high sensitivity of Raman spectra to the length of the chain - make it possible in the synthesis process to predict and adjust in real time the molecular weight of oligomers and other target properties, and replacing a fleet of traditional analytical equipment with one method.

Forefront of Semiconductor Evaluation by Laser Raman Spectroscopy

Forefront of Semiconductor Evaluation by Laser Raman Spectroscopy

Improved ionic conductivity and structural transition from (nLi2S-LiI)-(P2S5) solid solutions to LixP2SyI crystalline electrolytes

In this study, LixP2SyI – type crystalline lithium superionic conductors have been synthesized from nLi2S-LiI (n = 1, 2, 3, and 4) solid solutions and P2S5 using the high energy ball milling process. First, different concentrations of Li2S were mixed and ball-milled with LiI at different molar ratios to obtain various Li2S-LiI solid solutions (nLi2S-LiI). Then, P2S5 was added to the prepared nLi2S-LiI solid solutions to get crystalline solid electrolytes. The crystalline nature and the composition of the prepared nLi2S-LiI solid solutions, and P2S5 added nLi2S-LiI (LixP2SyI) crystalline solids were examined using the powder X-ray diffraction technique. The evolution of the crystalline structural units was captured by laser Raman spectroscopy analysis. The surface morphology changes with varying Li2S concentrations as well as the addition of P2S5 were studied using field emission scanning electron microscopy. Electrochemical impedance spectroscopy analysis revealed that the prepared Li5S2I (3.1 ×10−5 S cm−1) and Li7P2S8I (1.07 ×10−3 S cm−1) solid electrolytes exhibited higher ionic conductivities than the other nLi2S-LiI solid solutions and LixP2SyI crystalline solids, respectively. The result of cyclic voltammetry analysis and DC polarization analysis proved that the prepared nLi2S-LiI solid solutions and LixP2SyI crystalline solids are stable against lithium metal. All-solid-state lithium batteries fabricated using nLi2S-LiI solid solutions and LixP2SyI crystalline solid electrolytes showed comparable electrochemical performances. In the present study, we demonstrated nLi2S-LiI solid solutions and LixP2SyI crystalline solids which could potentially be used as solid electrolytes for the fabrication of ASSBs with good performance.

Indigenous carbon-rich matter associated with unusual aqueous alteration features in Nakhla: Complex formation and preservation history

While indigenous organic matter has been previously reported in the Mars meteorite Nakhla, little is known as to either its form or distribution. A notable feature of Nakhla is the prevalence of secondary phases associated with aqueous alteration. By analogy with the terrestrial environment, our objective was to determine whether Martian secondary minerals could also act to accumulate and preserve such organic matter. Through a multidisciplinary approach, we have characterized the nature of carbonaceous matter and spatially associated phases within the Martian meteorite Nakhla using a wide-ranging suite of analytical instrumentation including optical microscopy, laser Raman spectroscopy, focused ion beam microscopy, secondary ion mass spectrometry, and scanning and transmission electron microscopy. In freshly fractured chips of Nakhla, we found carbonaceous phases intimately associated with secondary aqueous alteration phases, both mineral and amorphous, interpreted to have formed through the low-temperature aqueous dissolution of the host basalt while on Mars. The carbonaceous matter is present both in condensed phases and in a dispersed state spatially associated with secondary alteration phases. In the former, we identified discrete refractory micron to submicron assemblages that appear macromolecular in nature and, in several cases, associated with fluorine and, in one case, significant nitrogen. Textural, chemical, mineralogical and isotopic considerations argue for a non-terrestrial origin of this carbonaceous matter. Additionally, we report the presence of the ferrous hydroxycarbonate mineral chukanovite (Fe2OH2CO3) within some of the secondary mineral aggregates studied. Neither the intimate association of carbonaceous matter with secondary phases nor the identification of chukanovite have been previously reported in any of the Martian meteorites. In this regard, we note such microscale features within alteration phases would most likely be lost in the preparation of conventional polished thin sections and thus explain why they have not been previously reported. In lieu of sample return, the sui generis nature provided by Mars meteorites provide insight to alteration processes on Mars currently denied to robotic exploration and remote sensing. Our results show a variety of habitability-related sample attributes, formed hundreds of millions of years ago near Mars’ surface, have persisted there until very recently and may be more widespread in the surface regolith than previously thought. This may have implications in sample selection criteria for Mars sample return.

Genesis and mineralization style of gold occurrences of the Lower Lom Belt, Bétaré Oya district, eastern Cameroon

The Bétaré Oya district has a substrate composed of the Neoproterozoic metavolcanic-metasedimentary rocks of the Lom Belt in eastern Cameroon. The district is well-known for alluvial gold mining activities, however, the primary gold mineralization has received little attention. In the current study, we newly report geological, ore mineralogy, fluid inclusion microthermometric, laser Raman spectroscopy, and stable isotope data from auriferous veins of the Lom Belt to characterize the style of gold mineralization and to constrain the origin of the ore-forming fluids. The auriferous quartz veins are laminated, fractured, N- to NE-trending, and spatially associated with the Bétaré Oya Shear Zone. Fieldwork coupled with microscopic examination and the textural relationships of ore minerals revealed two stages of mineralization. The first stage is characterized by the presence of pyrite, sphalerite, galena, chalcopyrite, pyrrhotite, hematite, petzite, hessite, wolframite, electrum, and gold, while the second stage is characterized by the presence of a later deposition of galena and pyrite, as well as minor greenockite. The gangue minerals are quartz, sericite, muscovite, chlorite, calcite, ankerite, and barite, whereas the supergene assemblage (stage 3) includes goethite, hematite, covellite, and enargite. Two fluid inclusion assemblages containing three types of inclusions are identified in mineralized quartz veins. Assemblage 1 consists of gold-related types 1 and 2 with daughter minerals consisting of nahcolite, magnesite, and arsenolamprite (black native arsenic), whereas assemblage 2 consists of post-gold type 3 fluid inclusions. Type 1 has H2O-NaCl-CO2 ± N2 ± CH4 primary fluid inclusions (FI), with a TmCO2 ranging from −59.8 to −56.6 °C, salinities from 0.5 to 10.8 wt% NaCl eq., densities from 0.87 to 1.00 g.cm−3, and total homogenization temperatures between 280 and 360 °C. Type 2 contains CO2 (±H2O-NaCl) ± N2 ± CH4 FI that exhibit TmCO2 ranging between −60.0 and −56.7 °C, ThCO2 from 13 to 25 °C, and densities between 0.73 and 0.85 g.cm−3. Type 3 shows H2O-NaCl FI with salinities between 0.2 and 10.1 wt% NaCl eq., densities between 0.82 and 0.98 g.cm−3, and total homogenization temperatures from 160 to 235 °C. Measured δ18O for gold-bearing quartz (+11.5 to +16.0‰), δD from FI (−50.6 to −21.8‰), δ13C from FI (−5.8 to −5.5‰), and δ34S from galena and pyrite grains (+5.3‰ and +8.2‰, respectively) suggest a metamorphic source as most likely for the ore-forming fluids and sulfur, although a mantle CO2 contribution cannot be ruled out.The gold deposition probably took place by fluid-rock interaction and fluid unmixing at ∼310 °C and at a depth of about 6–9 km. The ore-forming fluid was a low salinity (∼6.2 wt% NaCl eq.) H2O-NaCl-CO2 ± N2 ± CH4 solution. These data revealed that the Lom Belt gold mineralization is best classified as a mesozonal orogenic gold deposit.

Synergistic Flame-Retardant Effect of Aluminum Diethyl Phosphinate in PP/IFR System and the Flame-Retardant Mechanism

Abstract Synergistic flame-retardant effect of aluminum diethyl phosphinate (AlPi) in intumescent flame retardant polypropylene (PP/IFR) system and the flame-retardant mechanism were investigated. The flame retardancy of PP/IFR/AlPi (the mass ratio of IFR to AlPi is 2 : 1) was the best, which was proved by the results of the limiting oxygen index (LOI) test, UL-94 test, and cone calorimeter test ( CCT) test. Here, the LOI value of the sample was as high as 34% and passed the V–0 rating in UL–94 test. The peak heat release rate (PHRR) decreased by 92.57%, the total heat release (THR) reduced by 90.52%. Thermogravimetric (TGA) data showed that the introduction of AlPi improved thermal stability and changed the thermal degradation behavior of PP/IFR composites. Interestingly, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDXS) and laser Raman spectroscopy (LRS) proved that PP/IFR/AlPi had formed more residual carbon, but the flame retardancy was worse than PP/IFR/AlPi. This is because when the mass ratio of IFR to AlPi is 2 : 1, the synergy between IFR and AlPi was significant, gas-phase flame retardant and condensed-phase flame retardant reached a balance and obtained the best flame retardant effect.

Longitudinal debonding in unidirectional fibre-reinforced composites: Numerical analysis of the effect of interfacial properties

Longitudinal fibre-matrix debonding is governed by interfacial strength, fracture toughness, thermal residual stresses, friction, and matrix plasticity. The proposed finite element model for fibre-matrix longitudinal debonding associated with fibre breakage accounts for these features, retrieving more realistic results for the stress redistribution around a fibre break. In contrast with the majority of the available finite element models, the current model does not impose the debond length and enables debond propagation based on the assigned interfacial properties. Several parametric studies have been performed to assess the effect of input parameters in two configurations: single- and multi-fibre packings. Higher values for interfacial friction coefficient, thermal residual stress and interfacial fracture toughness restrain the debond propagation and consequently accelerate the stress recovery. Conversely, including matrix plasticity facilitates the debond propagation. A prescribed matrix crack, concentric with the broken fibre and as large as thrice the fibre radius, has no significant effect on the extent of the debond but increases the stress concentration on the nearest intact fibres in the multi-fibre model. The results of the proposed finite element model match the reported laser Raman spectroscopy literature data [1]. The current study improves the prediction capability of models for the longitudinal tensile failure of unidirectional composites.

Iterative differential autoregressive spectrum estimation for Raman spectrum denoising

AbstractAlthough ultraviolet (UV) laser Raman spectroscopy offers the benefits of stronger signals, partial separation of fluorescence and Raman spectra, and increased eye safety, it suffers from excessive noise, poor resolution, low maturity level, and small intensities of remotely acquired signals and therefore needs to be used in combination with effective denoising techniques. Herein, a denoising approach denoted as iterative differential autoregressive spectrum estimation was developed relying on the assumption that more detailed Raman peaks can be obtained by dividing the Raman spectrum into multiple layers with different intensity levels and estimating the energy distribution of each layer. Specifically, each layer was computed from the difference between the upper layer spectrum and its autoregressive model estimation spectrum, and the energy distribution at progressively lower intensity levels was considered. Compared with traditional techniques, our method exhibited good noise suppression performance and an excellent Raman peak restoration ability while offering the advantages of decreased spectral resolution loss and stable robustness. Cutoff optimization strategies were proposed to improve convergence and noise suppression ability and thus decrease the calculation time to 0.18 s and meet the needs of remote Raman spectrometers for real‐time denoising under the condition of long integration. The developed technique paves the way to Raman spectrum denoising based on power spectrum estimation, has a strong adaptive potential, and can be extended to other applications.

Antibacterial Property of Cellulose Acetate Composite Materials Reinforced with Aluminum Nitride.

Cellulose acetate (CA) is a synthetic compound that is derived from the acetylation of cellulose. CA is well known as it has been used for many commercial products such as textiles, plastic films, and cigarette filters. In this research, antibacterial CA composites were produced by addition of aluminum nitride (AlN) at different weight percentage, from 0 wt. % to 20 wt. %. The surface characterization was performed using laser microscope, Raman and FTIR spectroscopy. The mechanical and thermal properties of the composite were analyzed. Although the mechanical strength tended to decrease as the concentration of AlN increased and needed to be optimized, the melting temperature (Tm) and glass transition temperature (Tg) showed a shift toward higher values as the AlN concentration increased leading to an improvement in thermal properties. AlN additions in weight percentages >10 wt. % led to appreciable antibacterial properties against S. epidermidis and E. coli bacteria. Antibacterial CA/AlN composites with higher thermal stability have potential applications as alternative materials for plastic packaging in the food industry.

Geochronology, Fluid Inclusions and Isotopic Characteristics of the Dongjun Pb‐Zn‐Ag Deposit, Inner Mongolia, NE China

AbstractThe Dongjun Pb‐Zn‐Ag deposit in the northern part of the Great Xing'an Range (NE China) consists of quartz‐sulfide vein‐type and breccia‐type mineralization, related to granite porphyry. Hydrothermal alteration is well‐developed and includes potassic‐silicic‐sericitic alteration, phyllic alteration and propylitic alteration. Three stages of mineralization are recognized on the basis of field evidence and petrographic observation, demarcated by assemblages of quartz‐pyrite‐arsenopyrite (early stage), quartz‐polymetallic sulfide (intermediate stage) and quartz‐carbonate‐pyrite (late stage). Zircon LA‐ICP‐MS U‐Pb dating indicates that the granite porphyry was emplaced at 146.7 ± 1.2 Ma (Late Jurassic). Microthermometry and laser Raman spectroscopy shows that ore minerals were deposited in conditions of intermediate temperatures (175–359°C), low salinity (0.5–9.3 wt% NaCl eqv.) and low density (0.60–0.91 g/cm3). Ore‐forming fluids were derived largely from magmatic hydrothermal processes, with late‐stage addition of meteoric water, belonging to a H2O‐NaCl‐CO2 ± CH4 system. The δ34SV‐CDT values range from 0.75‰ to 4.70‰. The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb values of the ore minerals are in the ranges of 18.240–18.371, 15.542–15.570, and 38.100–38.178, respectively. Data for the S and Pb isotopic systems indicate that the ore‐forming metals and sulfur were derived from Mesozoic magma. Based on the geological characteristics and geochemical signatures documented in this study, we conclude that the Dongjun deposit is a mesothermal magmatic hydrothermal vein‐type Pb‐Zn‐Ag deposit controlled by fractures and related to granite porphyry, in response to Late Jurassic tectonic–magmatic–hydrothermal activity. We further conclude that fluid immiscibility, fluid mixing and fluid‐rock interactions were the dominant mechanisms for deposition of the ore‐forming materials.

Geochemical and geochronological evidence of meteorite impact excavating the Archean basement at Lonar Crater, Central India

The effect of meteorite impact on basement rocks remains widely debated at Lonar Crater, Central India. We investigate an impact melt-bearing rock from the ejecta layer of Lonar to assess the potential interaction of the projectile with the underlying Archean basement. The investigated sample is a melanocratic, aphanitic melt rock comprising glassy inclusions, and plagioclase and quartz clasts. Plagioclase and quartz show shock-induced features including diaplectic glass and well-developed planar deformation features (PDFs), respectively. The decrease in shock pressure is thus established with the plagioclase of overlying basalt showing shock features like diaplectic glass whereas the quartz from lower Archean basement showing PDF development. Laser Raman spectroscopy reveals the presence of cristobalite. The impact melt-bearing rock shows major element geochemistry similar to that of Deccan basalt with a tholeiitic trend, but the Harker variation plots reveal an independent field for the melt rock between the two end members: Deccan basalt and Archean basement represented by Peninsular gneiss. The REE geochemistry also reveals more fractionation for the melt rock. Zircon U-Pb data indicate an upper intercept age around 3.0 to 3.1 Ga. Chondrite normalized zircon REE data display a positive Eu anomaly indicating a reheating during the impact event. This indicates that the melt rock sample was generated by the incorporation of Archean basement gneiss components, which is compatible with the estimated depth of excavation for an impact structure of this size. This specifies a depth to basement in the range between 522 and 570 m.

Synthesis of phosphorus and silicon co‐doped graphitic carbon nitride and its combination with ammonium polyphosphate to enhance the flame retardancy of epoxy resin

AbstractPhosphorus and silicon co‐doped graphitic carbon nitride (PSiCN) was synthesized by inducing the polycondensation reaction of melamine, diammonium hydrogen phosphate, and silicic acid. The structure and thermal properties of PSiCN were characterized. With the incorporation of 2 wt% of PSiCN and 8 wt% of ammonium polyphosphate (APP), EP/2PSiCN‐8APP composite exhibited a limiting oxygen index value of 29.0% and passed a UL‐94V‐0 rating, which reached the refractory level. The thermogravimetric analysis confirmed that the addition of PSiCN and APP improved the thermal stability of the composites. The cone calorimetry test (CCT) revealed that the peak of heat release rate, total heat release, the peak of smoke production rate and total smoke production of EP/2PSiCN‐8APP composite was reduced by 71.1%, 53.5%, 65.4%, and 53.5%, respectively, compared with pure EP. Furthermore, the residues after CCT were evaluated by scanning electron microscopy, laser Raman spectroscopy and Fourier transform infrared spectroscopy, and the flame retardant mechanism of EP/2PSiCN‐8APP composite was proposed. Finally, the parallel arrangement of the aromatic ring and the surface of the PSiCN and the synergistic effect of the P/N/Si multi‐element resulted in EP/2PSiCN‐8APP with excellent mechanical properties.

Raman spectroscopy shows difference in drugs at ultra high dilution prepared with stepwise mechanical agitation

Abstract
 
 
 Objective
 
 
 The present study aims at deciphering the nature of the water structure in two drugs at ultra high dilution (HD) by Laser Raman Spectroscopy.
 
 
 Method
 
 Two drugs like Sulphur and Natrum mur and their three high dilutions 30cH, 200cH and 1000cH were selected for the study. The 30cH means dilution 1060 with mechanical agitation in 30 steps.Raman spectra of the drugs and their medium (90%ethanol)were obtained in the wave number region of 2600-3800 cm-1. The intensity ratio at vibration frequencies between 3220 and 3420 (R1) and that between 3620 and 3420 (R2) were calculated for each HD as well as the control.
 
 
 Results
 
 Raman spectra show differences in intensities in different HD’s and their control in the stretching vibrations of CH and OH groups. The three HD’s of each drug show inverse relationship with respect to the R1 values. However, for R2 the relationship of HD’s for each drug is positive.
 
 Conclusion
 
 R1 provides information about the relative number of OH groups with strong and weak hydrogen bonds. R2 suggests the relative number of OH groups with broken and weak hydrogen bonds. Judged from R1 values the lower is the rank of HD, the stronger is the H-bond of the OH groups. In the light of R2 values the higher is the HD rank the more abundant is the free OH groups. So, hydrogen bond strength and free OH groups together make an effective HD rank relating to Sulphur and Natrum mur.