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Plant diseases pose a significant threat to plant and crop health, leading to reduced yields and economic losses. The traditional methods for diagnosing plant diseases are often invasive and time-consuming and may not always provide accurate results. In recent years, there has been growing interest in utilizing Raman microscopy as a non-invasive and label-free technique for plant disease diagnosis. Raman microscopy is a powerful analytical tool that can provide detailed molecular information about samples by analyzing the scattered light from a laser beam. This technique has the potential to revolutionize plant disease diagnosis by offering rapid and accurate detection of various plant pathogens, including bacteria and fungi. One of the key advantages of Raman microscopy/spectroscopy is its ability to provide real-time and in situ analyses of plant samples. By analyzing the unique spectral fingerprints of different pathogens, researchers can quickly identify the presence of specific diseases without the need for complex sample preparation or invasive procedures. This article discusses the development of a Raman microspectroscopy system for disease diagnosis that can accurately detect and identify various plant pathogens, such as bacteria and fungi.

The symbiotic relationship between corals and their associated microorganisms is crucial for the health of coral reef eco-environmental systems. Recently, there has been a growing interest in unraveling how the manipulation of symbiont nutrient cycling affects the stress tolerance in the holobiont of coral reefs. However, most studies have primarily focused on coral–Symbiodiniaceae–bacterial interactions as a whole, neglecting the interactions between Symbiodiniaceae and bacteria, which remain largely unexplored. In this study, we proposed a hypothesis that there exists an inner symbiotic loop of Symbiodiniaceae and bacteria within the coral symbiotic loop. We conducted experiments to demonstrate how metabolic exchanges between Symbiodiniaceae and bacteria facilitate the nutritional supply necessary for cellular growth. It was seen that the beneficial bacterium, Ruegeria sp., supplied a nitrogen source to the Symbiodiniaceae strain Durusdinium sp., allowing this dinoflagellate to thrive in a nitrogen-free medium. The Ruegeria sp.–Durusdinium sp. interaction was confirmed through 15N-stable isotope probing–single cell Raman spectroscopy, in which 15N infiltrated into the bacterial cells for intracellular metabolism, and eventually the labeled nitrogen source was traced within the macromolecules of Symbiodiniaceae cells. The investigation into Symbiodiniaceae loop interactions validates our hypothesis and contributes to a comprehensive understanding of the intricate coral holobiont. These findings have the potential to enhance the health of coral reefs in the face of global climate change.

Cangjie Temple was built to commemorate Cangjie, the legendary inventor of Chinese characters. It stands as one of the few remaining temples in China dedicated to the invention and creation of writing. In this study, the material properties of wooden paintings from the Cangjie temple were characterized using Polarized Light Microscopy (PLM), Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (SEM-EDS), Micro-confocal Raman Spectroscopy, X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Pyrolysis-Gas Chromatography-Mass Spectrometry (Py-GC/MS). It was confirmed that the pigments of the paintings included cinnabar, lapis lazuli, lead white, Paris green, and carbon black. The proteinaceous glue was used as an adhesive in the pigment samples, with tung oil likely being utilized as a primer for the wooden structures before painting. This study not only provides valuable data support for the conservation and restoration of the architectural features of Cangjie Temple but also provides useful reference for the maintenance and inheritance of similar ancient buildings.

Understanding composition-structure-property relationships is critical to developments and applications of novel microwave dielectric ceramics used in the field of wireless communications. Herein, a series of CeZr1·14Bi0.045A0.045Mo4·5O18 (abbreviated as CZA, A = Nb, Ta and Sb) ceramics were prepared through a solid-state reaction method. Density and scanning electron microscope results revealed dense and homogeneous microstructures. X-ray diffraction analysis indicated the formation of solid solutions. Accordingly, the effects of extrinsic factors were negligible and thus composition-structure-property relationships were systematically investigated by the combination of the chemical bond theory, Raman spectroscopy, far-infrared (FIR) spectroscopy and terahertz time-domain spectroscopy (THz-TDS) from an intrinsic perspective. Interestingly, the measured dielectric constants (εr) and quality factors (Q × f) are quite close to the extrapolated values from FIR and THz-TDS, and these values show a similar trend with varying components. In addition, Mo–O bonds play an important role in the coefficient of thermal expansion (α) and bond energy (E), and the composition dependent temperature coefficient of the resonance frequency (τf) can be well explained by variations of mean α and E of Mo–O bonds. Typically, excellent properties of Q × f = 116,485 GHz (at 9.58 GHz), εr = 9.91 and τf = −19.20 ppm °C−1 were achieved for the CZSb ceramic sintered at 700 °C. Notably, Q × f values of CZSb and CZTa ceramics are 6.13 and 4.16 times larger than that of the matrix, respectively. Ultra-high Q × f, low sintering temperatures (600 − 700 °C) and low εr make them potential candidates for low temperature co-fired ceramics (LTCC) applications.

Spinel type nano ferrite compound MgFe2O4 was synthesized through sol gel technique using metal nitrates as precursors. The phase composition, morphology and elemental analysis of magnesium ferrite (MgFe2O4) were performed by X-ray diffraction, fourier transform infrared, atomic force microscopy, energy dispersive x-ray and scanning electron microscopy, analyses. The sample's X-ray diffraction pattern verifies the existence of single phase material, with the size of its crystallites estimated to be 39.9 nm. Fourier transform infrared examination supported metal-oxygen vibrations corresponding to tetrahedral and octahedral sites, respectively. From scanning electron microscopy image, grain size obtained about 97.7 nm. Raman spectra of the sample shows five Raman active modes (A1g + Eg + 3F2g), which is compatible with the spinel structure. Magnetic measurement study at room temperature shows a hysteresis loop behaviour with a low saturation magnetization value, 27.192 emu g-1 and a small coercivity value. The optical band gap determined using UV-visible transmittance spectra. Additionally, X-ray photoelectron spectroscopy are used to confirm oxidation states and explore the chemical composition of the sample.

The initial triggering mechanism of nitromethane is investigated by first-principles molecular dynamics simulations and temperature-dependent Raman spectroscopy experiment. The Raman spectra at different temperature are obtained by Car-Parrinello molecular dynamics simulation to explore the activated vibration modes caused by low-temperature heat. The temperature-dependent Raman spectra experiment is constructed to compare with the theoretical data. Each possible initial reaction path caused by the activated vibration mode is analyzed to reveal the triggering mechanism of the initial chemical bond breaking for nitromethane. The results show that the intermolecular double-proton transfer is the first reaction step which is triggered by the intermolecular hydrogen bond reinforced with the active C–H stretching vibration (near 3000 cm−1), which is not reported before. The scanning energy barrier related to the increase of C–H bond lengths is about 60 kcal/mol, which is consistent with the calculated activation barrier (59.8 kcal/mol) of intermolecular proton transfer reaction. This proves the reliability of our conclusions. The results provide a new interpretation for the long-debated initial decomposition mechanism of nitromethane.

This work presents the results of the study of structural, substructural and optical properties of Zn2SnO4 nanoparticles (NPs) and films. NPs synthesized by the hydrothermal method during 28 h were chosen to form a nanoink from which films were obtained by spraying the solution it on glass substrates. Obtained Zn2SnO4 films were annealed in Argon atmosphere at Ta = (250–500) °C for 30 min and 60 min to remove organic impurities and optimize the film's physical properties. Since the choice of mineralizer determines a number of important characteristics of nanoparticles, a comprehensive study of the obtained samples grown using KOH as a mineralizer was conducted. The samples were characterized by X-ray diffraction analysis, Energy Dispersive X-ray (EDX) analysis, high-resolution transmission (HRTEM) and scanning electron (SEM) microscopy, Raman and optical spectroscopy. Analysis of morphology showed that synthesized films have a [220] growth texture with inverse spinel structure and consist of NPs, the size of which increases with the annealing temperature (Ta). It was identified that the size of the coherent scattering domain (CSD) in the sample increases with increasing Ta, while the level of microdeformations decreases. Raman spectra showed F2g(2), F2g(3) and A1g modes corresponding to the structure of inverse spinel Zn2SnO4. It is found, that the optical bandgap Eg of NPs decreases from 4.02 eV to 3.85 eV with an increase in growth time. On another hand, the optical bandgap Eg of films decreases with an increase in annealing temperature, Ta, from 4.04 eV to 3.63 eV.

A series of LiIn1‐xAlxO2 (x =0.05, 0.10, 0.15, 0.20, 0.25) microwave dielectric ceramics with low permittivity were synthesized via a solid‐state reaction method. XRD, Raman spectra, and SEM analysis reveal that a single LiInO2 tetragonal structure phase could be obtained at the x < 0.10, and with the x increased further to 0.15–0.25, the diffraction peaks of the secondary phase LiAlO2 were detected. In the LiIn1‐xAlxO2 ceramics, the τf was closely related to the εr, and the relative density, microstructure, and microwave dielectric properties were effectively improved by the Al3+ substitution for In3+. Bond valence theory analysis demonstrates that the Al3+ entered the In3+ site exhibits a strength rattling effect, which is beneficial to the increase of εr. While Al3+ substitution for In3+ simultaneously lowers the average ionic polarizability, resulting in a decrease in εr. A near‐zero τf (0.74 ppm/°C) combined with εr approximately 12.83, Q × f = 58 200 GHz, was obtained in LiIn0.85Al0.15O2 ceramic sintered at 970°C. [ABSTRACT FROM AUTHOR]

Two routes of the dehydration process of theophylline monohydrate have been proposed in this work from mid-frequency Raman difference spectra (MFRDS) results and experiments. MFRDS can establish short-range order correlations among various theophylline crystal forms. MFRDS results indicate that the short-range order of metastable Form III is most similar to that of monohydrate, which explains that Form III is the main dehydration products in the mild dehydration process. The phenomenon that unstable amorphous theophylline intermediate phase would appear during the dehydration process of theophylline monohydrate was confirmed indirectly by Powder X-ray Diffraction (PXRD) and optical microscope and reported in the previous reports, which could cause the nucleation of Form II, as MFRDS results indicate short-range order of amorphous solid dispersion of theophylline is most similar to that of Form II. MFRDS analysis shows the advantages in studying the phase transformation of small organic molecule crystals. [ABSTRACT FROM AUTHOR]

Here, we present Raman spectra showing the presence and distribution of scytonemin and carotenoids in epilithic and endolithic colonisations from temperate locations in Central Europe and Sicily. In the Bohemian Massif, marble and serpentinitic cyanobacterial epiliths dominated by cyanobacteria Scytonema, Stigonema, Hassallia, Gloeocapsopsis and Gloeocapsa were investigated using light microscopy and Raman spectroscopy. Scytonemin was a common dark pigment, accompanied by carotenoids and gloeocapsin on the marbles from Opolenec and on serpentinites from Holubov (South Bohemia). Raman spectra from other sites originated from endolithic colonisations of gypsum. They were located in the Carpathian foredeep (Badenian, Silesian unit, eastern Poland) and in Messinian complexes in the Mediterranean area (Sicily). Similarly to the previous localities, almost ubiquitous occurrence of scytonemin confirmed the presence of cyanobacterial colonisations. Obtained findings are important from the spectroscopic point of view. Additionally, comparing results from several sites confirmed the common occurrence of scytonemin in both endoliths and epiliths from areas that cannot be considered climatically extreme, although they experience rapid fluctuations in temperature, humidity and UV irradiation on the exposed rocky substrates. [ABSTRACT FROM AUTHOR]

An ammonium-bearing fluorapophyllite-(K) occurs as a late hydrothermal product in the outer endoskarn zone from Aleului Valley (N 46°37′04″, E 22°35′22″), located at the contact of the granodiorite laccolith from Pietroasa, of Upper Cretaceous age, with Anisian dolostones. Associated minerals are wollastonite, K feldspar, diopside, fluorapatite, talc, and pectolite. The chemical structural formula is [K0.985Na0.012(NH4)0.076]Σ=1.073(Ca4.009Mn0.001Fe2+0.003Mg0.002Ba0.001)Σ=4.016(Si7.953Al0.047) O20.029[F0.899(OH)0.101]·8.059H2O. The structure was successfully refined as tetragonal, space group P4/mnc, with cell parameters of a = 8.9685(1) Å and c = 15.7885(5) Å. The indices of refraction are ω = 1.534(1) and ε = 1.536(1). The calculated density is Dx = 2.381 g/cm3, in good agreement with the measured density, Dm = 2.379(4) g/cm3. The thermal analysis shows that the mineral completely dehydrates at up to 450 °C (endothermic effects at 330, 371, and 448 °C) and loses ammonium at 634 °C. In the infrared spectra, the multiplicity of the bands assumed to be silicate modes (1ν1 + 3ν3 + 2ν2 + 3ν4) agrees with the reduction in the symmetry of the SiO44− ion from Td to Cδ. Fluorapophyllite-(K) from Aleului Valley is of late hydrothermal origin and crystallized from F-rich fluids originating from the granodiorite intrusion, which mobilized K, Ca, and Si from the pre-existing feldspar. [ABSTRACT FROM AUTHOR]

The electrical conductivity of LiCl-GdCl3 molten systems with the gadolinium chloride additions ranging from 0 to 23 mol % was measured depending on both the temperature and concentration of GdCl3. The molar conductivity of the molten GdCl3-LiCl system is calculated taking into account the assumption of additivity of the molar volume of the mixture. The obtained temperature dependencies can be approximated by Arrhenius-type equation. The effective activation energy, Ea, increased with the GdCl3 content. The liquidus temperatures of the studied systems were determined by differential scanning calorimetry. The high-temperature Raman spectra of LiCl-GdCl3 chloride melts were recorded. In addition, the conductivity of 0.77LiCl-0.23GdCl3 molten system with 1 mol % of Gd2O3 was measured. The investigation demonstrates that the addition of gadolinium oxide results in a decrease of the conductivity of the chloride molten system and growth of its liquidus temperature. [ABSTRACT FROM AUTHOR]

We investigated the effect of the elemental substitution of As by Sb on the threshold behaviours in GexAs(Sb)10Se90-x glasses. We found that, while the transition thresholds at MCN=2.4 and 2.67 were verified in the GeAsSe glasses, the transition thresholds can be changed to chemically stoichiometric compositions if As is substituted by Sb. We further deconvolved Raman spectra into different structural units and the change of their respective intensity showed the same behaviour, and this was ascribed to the chemical effect induced by a large difference of the atomic radius between As and Sb, and a relatively strong ionic feature of the element Sb. [ABSTRACT FROM AUTHOR]

This paper reports the conversion of a waste to a conducting material, exploiting the ability to adsorb pollutant organic dyes. Leather waste was carbonized at 800 °C in an inert nitrogen atmosphere. The resulting biochar was used for in-situ deposition of polypyrrole nanotubes produced by the oxidative polymerization of pyrrole in the presence of methyl orange. The composites of carbonized leather with deposited polypyrrole nanotubes of various composition were compared with similar composites based on globular polypyrrole. Their molecular structure was characterized by infrared and Raman spectra. Both conducting components formed a bicontinuous structure. The resistivity was newly determined by a four-point van der Pauw method and monitored as a function of pressure applied up to 10 MPa. The typical conductivity of composites was of the order of 0.1 to 1 S cm−1 and it was always higher for polypyrrole nanotubes than for globular polypyrrole. The method also allows for the assessment of mechanical features, such as powder fluffiness. The conductivity decreased by 1–2 orders of magnitude after treatment with ammonia but still maintained a level acceptable for applications operating under non-acidic conditions. The composites were tested for dye adsorption, specifically cationic methylene blue and anionic methyl orange, using UV-vis spectroscopy. The composites were designed for future use as functional adsorbents controlled by the electrical potential or organic electrode materials. [ABSTRACT FROM AUTHOR]

Background: Today, artificial intelligence-based computational approach is facilitating multitasking and interdisciplinary analytical research. For example, the data gathered during an analytical research project such as spectral and chromatographic data can be used in predictive experimental research. The spectral and chromatographic information plays crucial role in pharmaceutical research, especially use of instrumental analytical approaches and it consume time, man power, and money. Hence, predictive analysis would be beneficial especially in resource-limited settings. Main body: Computational approaches verify data at an early phase of study in research process. Several in silico techniques for predicting analyte's spectral and chromatographic characteristics have recently been developed. Understanding of these tools may help researchers to accelerate their research with boosted confidence and prevent researchers from being misled by incorrect analytical data. In this communication, the properties of chemical compounds and its relation to chromatographic retention will be discussed, as well as the prediction technique for UV/IR/Raman/NMR spectrograms. This review looked at the reference data of chemical compounds to compare the predictive ability in silico tools along with the percentage error, limitations, and advantages. Conclusion: The computational prediction of analytical characteristics offers a wide range of applications in academic research, bioanalytical method development, computational chemistry, analytical method development, data analysis approaches, material characterization, and validation process. [ABSTRACT FROM AUTHOR]

Samples of the Murchison meteorite (carbonaceous chondrite, type CM2) were kept isothermally in a specially designed device at temperatures of 200, 500, and 800°C. After the samples cooled down in an inert helium atmosphere, Raman scattering spectra were taken. An increase in the intensity of the G- and D‑lines of graphite was detected depending on the degree of heating. It is shown that using such a characteristic parameter of these lines as the area ratio, SD/SG, it is possible to define a geothermometer to determine the maximum temperature of thermal metamorphism of the parent bodies of carbonaceous chondrites. A comparison with the known data for carbonaceous chondrite Allende (CV3), which has experienced a significant thermal metamorphism, is carried out. [ABSTRACT FROM AUTHOR]

In In this study, the optical properties of magnesium-aluminate spinel were examined after being irradiated with 220 MeV Xe ions. The research aimed to simulate the impact of nuclear fuel fission fragments on the material. The following measurements were taken during the experiments: transmission spectra in the IR region (190–7000) nm, optical absorption spectra in the range (1.2–6.5) eV, and Raman spectra were measured along the depth of ion penetration from the surface to 30 µm. A peak with a broad shape at approximately 5.3 eV can be observed in the optical absorption spectrum of irradiated spinel crystals. This band is linked to the electronic color centers of F+ and F. Meanwhile, the band with a maximum at ~(3–4) eV is attributed to hole color centers. Apart from the typical Raman modes of an unirradiated crystal, additional modes, A1g* (720 cm−1), and Eg* (385 cm−1), manifested mainly as an asymmetric shoulder of the main Eg mode, are also observed. In addition, the Raman spectroscopy method showed that the greatest disordering of crystallinity occurs in the near-surface layer up to 4 μm thick. At the same time, Raman scattering spectroscopy is sensitive to structural changes almost up to the simulated value of the modified layer, which is an excellent express method for certifying the structural properties of crystals modified by swift heavy ions. [ABSTRACT FROM AUTHOR]

Dry reforming of methane with ratio CH4/CO2 = 1 is studied using supported Ni catalysts on SBA-15 modified by CeMnOx mixed oxides with different Ce/Mn ratios (0.25, 1 and 9). The obtained samples are characterized by wide-angle XRD, SAXS, N2 sorption, TPR-H2, TEM, UV–vis and Raman spectroscopies. The SBA-15 modification with CeMnOx decreases the sizes of NiO nanoparticles and enhances the NiO–support interaction. When Ce/Mn = 9, the NiO forms small particles on the surface of large CeO2 particles and/or interacts with CeO2, forming mixed phases. The best catalytic performance (at 650 °C, CH4 and CO2 conversions are 51 and 69%, respectively) is achieved over the Ni/CeMnOx/SBA-15 (9:1) catalyst. The peculiar CeMnOx composition (Ce/Mn = 9) also improves the catalyst stability: In a 24 h stability test, the CH4 conversion decreases by 18 rel.% as compared to a 30 rel.% decrease for unmodified catalyst. The enhanced catalytic stability of Ni/CeMnOx/SBA-15 (9:1) is attributed to the high concentration of reactive peroxo (O−) and superoxo (O2−) species that significantly lower the amount of coke in comparison with Ni-SBA-15 unmodified catalyst (weight loss of 2.7% vs. 42.2%). Ni-SBA-15 modified with equimolar Ce/Mn ratio or Mn excess is less performing. Ni/CeMnOx/SBA-15 (1:4) with the highest content of manganese shows the minimum conversions of reagents in the entire temperature range (X(CO2) = 4–36%, X(CH4) = 8–58%). This finding is possibly attributed to the presence of manganese oxide, which decorates the Ni particles due to its redistribution at the preparation stage. [ABSTRACT FROM AUTHOR]

Gd 2 Mo 3 O 12 ceramics were prepared using the traditional solid-phase reaction method. All samples were found to possess an orthorhombic crystal structure with a space group of Pba2, as revealed by refined XRD results. The ceramic sintered at 1000 °C exhibited a high relative density of 96.95 % and superior microwave dielectric properties, including ε r of 9.42 ± 0.05, × f of 49258 ± 1200 GHz, and τ f of −71.8 ± 0.7 ppm/°C. The results suggest a correlation between an increase in ε r and higher relative density, and a more compact and uniform microstructure can lead to higher × f value. Chemical bonding theories and Raman spectroscopy analysis reveal that Mo-O bonds, rather than Gd-O bonds, dominate the microwave dielectric properties. Furthermore, the ε r of Gd 2 Mo 3 O 12 ceramic was closely related to bond ionicity, while × f and τ f were mainly determined by lattice energy and bond energy, respectively. [ABSTRACT FROM AUTHOR]

SERS is widely used as a detection procedure in various analytical applications due to high sensitivity. One of the stages in the development of such methods is the identification of the compound to be quantified using reference spectra. High-intensity reference SERS spectra without extraneous bands are obtained in a wide spectral interval for an important analyte (2,3-diaminophenazine), the Raman scattering of which is enhanced by aggregated hydroxylamine sols of silver nanoparticles. [ABSTRACT FROM AUTHOR]

Protein‐nanoparticle conjugation, or protein‐corona, is important for nanomedicine, nano diagnostic, and nano therapy applications. α‐Bismuth oxide nanoparticles (α‐Bi2O3 NPs) were prepared from bismuth nitrate powder using the sol‐gel method and characterized using various techniques, including Energy Dispersive X‐Ray Spectroscopy (EDS), X‐ray Diffraction (XRD), Raman spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), UV‐VIS‐NIR Spectroscopy, and Brunauer‐Emmett‐Teller (BET). X‐ray diffraction studies revealed that NPs are in the alpha phase with a monoclinic structure. The energy band gap, average surface area and crystallite size are 2.81 eV, 2.42 m2, and 15–106 nm, respectively. Transmission electron microscopy revealed particle size is 32.21 nm, with a d‐spacing of 2.529 Å. The surface‐to‐volume ratio is calculated and found to be 2.553×106 m−1. For the first time, a direct protein interaction with NPs was examined with standard proteins such as bovine serum albumin (BSA), carbonic anhydrase, phosphorylase b, and total human serum proteins and analyzed using mass spectroscopy. Proteomic analysis showed that proteins such as BSA, phosphorylase b, and carbonic anhydrase exhibited a strong affinity with Bi2O3 NPs. However, it was found that there was less or no association between Annexin A6, human serum albumin, Zinc finger protein, and Bestrophin‐2 with Bi2O3 NPs. [ABSTRACT FROM AUTHOR]

Thin-layered materials from transition-metal dichalcogenides family and their preforms such as molybdenum three oxides (MoO3) exhibit great potential as active material in optoelectronics. Stable materials of few atoms thick have shown emerging capabilities in this area. In this article, we report the synthesis of MoO3 nanostructures by spray pyrolysis method. We will, perhaps for the first time, show that by varying the hot plate temperature from 350 to 440° C, a phase transformation reveal from h-MoO3 to α-MoO3. By annealing the prepared α-MoO3 sample a preferential orientation of (002) crystal plane is induced. A large bandgap of 2.8 eV for the prepared MoO3 film was obtained from the transmission spectra. The Raman vibrational modes were investigated for excitation wavelength at 532 nm using MoO3 films and for a heterostructured MoO3/MoS2 film. Better crystallinity and decrease in defects intensity, as an advantage of MoO3 hybridization can be achieved by proper bfaricating the heterostructure sample. [ABSTRACT FROM AUTHOR]

Gypsum (CaSO4·2H2O) has been identified at the surface of Mars, by both orbiters and rovers. Because gypsum mostly forms in the presence of liquid water as an essential element for sustaining microbial life and has a low porosity, which is ideal for preserving organic material, it is a promising target to look for signs of past microbial life. In this article, we studied organic matter preservation within gypsum that precipitates in a salt flat or a so-called coastal sabkha located in Qatar. Sabkha's ecosystem is considered a modern analog to evaporitic environments that may have existed on early Mars. We collected the sediment cores in the areas where gypsum is formed and performed DNA analysis to characterize the community of extremophilic microorganisms that is present at the site of gypsum formation. Subsequently, we applied Raman spectroscopy, a technique available on several rovers that are currently exploring Mars, to evaluate which organic molecules can be detected through the translucent gypsum crystals. We showed that organic material can be encapsulated into evaporitic gypsum and detected via Raman microscopy with simple, straightforward sample preparation. The molecular biology data proved useful for assessing to what extent complex Raman spectra can be linked to the original microbial community, dominated by Halobacteria and methanogenic archaea, providing a reference for a signal that may be detected on Mars. [ABSTRACT FROM AUTHOR]

A series of rhenium compounds with the octahedral cluster core {Re6S8-xBrx} (x = 0–4): with molecular and polymeric structure were obtained. In these compounds the cluster core composition varies monotonically, the geometry of the cluster and the rhenium coordination polyhedron are retained unchanged, while the symmetry of the cluster changes. The vibrational spectra (Raman and IR) were recorded and analyzed for compounds with all possible S/Br ratios in the cluster core. The group vibrations of clusters were attributed with the use of DFT calculations of vibrational spectra. It is shown that the set of main characteristic bands is retained in both ionic and polymeric compounds regardless of the composition and the symmetry of the cluster core while the observed vibration frequencies of these bands depend on the S/Br ratio in the cluster core. In particular, the group Re–S stretching vibrations (A1g(S8) and T2g(S8) modes) shifted to higher frequencies with the increase in the number of Br atoms in the cluster. The difference in the connectivity in polymeric compounds leads to an increase in the number of bands in the spectra and to the disappearance of the A1g(Br) modes. [ABSTRACT FROM AUTHOR]

xMgO–(30–x)BaO–69.5B2O3 glass systems were synthesized with the doping of transition metal ions (Mn2+) by applying the melt quench method. These glass systems are then observed using analysis by XRD, UV-VIS absorption and electron paramagnetic resonance. Mn2+ absorption spectrum has its own broadband at about 21000 cm–1 (476 nm), which is ascribed to be of 6A1g(S) → 4T1g (G) transition. The typical six-line hyperfine structure with a core at g ≈ 2.0 was observed in the Mn2+ EPR spectra. The close octahedral site symmetry for the Mn2+ contamination ions was established by spectroscopic examinations of the obtained data. Structural transformations were discovered using Fourier transform infrared and Raman spectra. Assessments were done on several physical parameters, together with density, refractive index, optical basicity, molar volume, energy gap, Urbach energy and interaction parameter. [ABSTRACT FROM AUTHOR]

Thin-layered materials from transition-metal dichalcogenides family and their preforms such as molybdenum three oxides (MoO3) exhibit great potential as active material in optoelectronics. Stable materials of few atoms thick have shown emerging capabilities in this area. In this article, we report the synthesis of MoO3 nanostructures by spray pyrolysis method. We will, perhaps for the first time, show that by varying the hot plate temperature from 350 to 440° C, a phase transformation reveal from h-MoO3 to α-MoO3. By annealing the prepared α-MoO3 sample a preferential orientation of (002) crystal plane is induced. A large bandgap of 2.8 eV for the prepared MoO3 film was obtained from the transmission spectra. The Raman vibrational modes were investigated for excitation wavelength at 532 nm using MoO3 films and for a heterostructured MoO3/MoS2 film. Better crystallinity and decrease in defects intensity, as an advantage of MoO3 hybridization can be achieved by proper bfaricating the heterostructure sample. [ABSTRACT FROM AUTHOR]

L-Glycine Glycinium Hydrochloride Monohydrate (L-GGHCM), a new second-order nonlinear optical crystal, was produced using the slow evaporation process with double distilled water as a solvent. Powder XRD analysis was completed in order to identify the crystallinity sample. In the orthorhombic system with space group P 2 1 2 1 2 1 , L-GGHCM expands in accordance with structural improvement. A single crystal XRD analysis discovered the extended framework architecture of L-GGHCM, a self-assembly process involving short-range and directed bonds, among many other interactions. The optical quality and transmission of the synthesized crystal were determined using UV–visible and fluorescence spectrum analysis. The effectiveness of L-GGHCM's second harmonic generation is roughly 1.7 times compared to a standard potassium dihydrogen orthophosphate sample. Thermal analysis is used to study a material's thermal stability and internal decomposition. L-glycine glycinium hydrochloride monohydrate crystal is shown to have good thermal stability. [ABSTRACT FROM AUTHOR]

This research aims to deepen the understanding of the relationship between conductivity and morphology in polypyrrole (PPy) via a comparison of the bipolaron to polaron ratios with a focus on the C-H deformation area. PPy samples were synthesized with different surfactants: sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and tween 80 (TW). This study revealed that SDS significantly altered the bipolaron and polaron in the C-H deformation region and showed higher conductivity than other surfactants. Notably, the morphological shifts to a sheet-like structure when using ammonium sulfate (APS) contrasted with the particle-like form observed with ferric chloride (FeCl3). These results showed that if the oxidant changed, the bipolaron and polaron ratios in C-H deformation were unrelated to PPy morphology. However, this work showed a consistent relationship between SDS use, the bipolaron and polaron ratios in the C-H deformation, and the conductivity properties. Moreover, the natural positive charge of PPy and negatively charged SDS molecules may lead to an electrostatic interaction between PPy and SDS. This work assumes that this interaction might cause the transformation of polaron to bipolaron in the C–H deformation region, resulting in improved conductivity of PPy. This work offers more support for the future investigation of PPy characteristics.

Raman-active modes of human skin and pork belly have been studied systematically by a near-infrared Raman spectrometer with an exciting laser of 1064nm. The main components and quantitative determination of pork belly are extracted by fitting the Raman spectra with the normalized Raman spectra of biochemical reagents such as collagen, elastin, triolein, fibronectin, fibrin, and hyaluronic acid. It demonstrates that the main components and quantity are various at different locations of pork belly, while the main components of human skin are similar to those of pig skin. In a further step, the evolution of the heating time-dependent Raman modes of isolated pig skin has been investigated for the mechanism of burnt skin. One can find that the spatial structure and main components of skin have an excellent thermal stability in the temperature range from -120 to 200∘C, which is confirmed by the temperature dependent Raman spectra of isolated pig skin, microporous acellular dermal matrix (MADM) as well as their corresponding biochemical reagents (collagen, elastin, triolein, etc.). These results help understand the mechanism of the living skin burnt by fire or hot water, and supplies an alternative technology for surgeons to diagnose the depth of a burn injury in time.

The design and development of an alternative counter electrode (CE) using graphene-based low-cost material for the dye-sensitized solar cell (DSSC) is the major motivation of the current research to replace the traditional platinum counter electrode. Herein, we prepared reduced graphene oxide (rGO) and investigated it for an efficient CE in DSSC. The structural and morphological properties of rGO are analyzed using FESEM, TEM and Raman techniques. The performance of I3- reduction on the CE is characterized by the EIS Nyquist plot, cyclic voltammetry, and the Tafel curve. The measured electrochemical results suggested that rGO CE has a lower charge transfer resistance (Rct), higher cathodic current density (Jrd), and higher Tafel slope as compared to graphene oxide (GO) CE, revealing that rGO CE has good catalytic activity towards the I3- reduction.

The Raman scattering, infrared absorption, and reflection spectra of hexagonal non-centrosymmetric BaZnBO3F and BaAlBO3F2 and centrosymmetric BaZn3BO3F2 and BaZnCO3F2 are calculated using the standard procedures of the CRYSTAL package with the basis of localized orbitals and the B3LYP hybrid functional within the framework of the Hartree-Fock conjugate perturbation method. It is shown that the layered structure of crystals manifests itself in the spectra of vibrational modes polarized along and perpendicular to the c axis with wavenumbers for the lattice region formed by displacements of atoms in [BaF]∞ and [MAO3]∞ (M: Zn, Al; A: B, C) layers, for molecular deformation outside and in the plane of anions BO3 and CO3. The quantitative and qualitative composition of the spectra is determined by the symmetry of the crystal lattice. [ABSTRACT FROM AUTHOR]

Raman spectroscopy has proven its effectiveness as a highly informative and sensitive method for the nondestructive analysis of layered nanostructures and their interfaces. However, there is a lack of information concerning the characteristic phonon modes and their activity in Si/SiO2 nanostructures. In order to overcome this problem, the phonon states and Raman spectra of several Si/SiO2 superlattices (SL) with layer thicknesses varied within 0.5–2 nm are studied using DFT-based computer modeling. Two types of structures with different interfaces between crystalline silicon and SiO2 cristobalite were studied. A relationship between the phonon states of heterosystems and the phonon modes of the initial crystals was established. Estimates of the parameters of deformation potentials are obtained, with the help of which the shifts of phonon frequencies caused by elastic strains in the materials of the SL layers are interpreted. The dependence of intense Raman lines on the SL structure has been studied. Several ways have been proposed to use this information, both for identifying the type of interface and for estimating the structural parameters. The obtained information will be useful for the spectroscopic characterization of the silicon/oxide interfaces. [ABSTRACT FROM AUTHOR]

The structural and Raman spectroscopic analyses of La2-xBixMo1.95V0.05O9γ (0:075 - x - 0:200) are presented in this study. Reitveld refined XRD patterns indicate that the La-O1, La-O2, La-O3, and the average La-O bond length of lanthanum-oxygen polyhedral increases with Bismuth content. The average Mo-O bond length is found to be shortest for the composition x = 0:100, which correlates with the composition's highest conductivity and is also supported by the composition's shortest O2-O3 and O3-O bond distances. At x = 0:100, the La-La-La angle of the [O1LaMo] anti-tetrahedral unit is maximal, enabling greater O2 and O3 ion mobilities. From Raman study it is observed that Mo-O distance is minimal for the composition x = 0:100, which is also revealed by XRD outcome. [ABSTRACT FROM AUTHOR]

Simple Summary: Natural pearls of Diplodon chilensis, a freshwater clam native to southern South America, are reported and characterized for the first time. The finding also constitutes the first record of pearls in a species of the genus Diplodon. The pearls have different shapes and sizes, and were found in both, male and female specimens. The microstructure and chemical composition of pearls is consistent with those reported in other bivalve species. The capability to produce pearls is widespread in the phylum Mollusca, including bivalves of the superfamily Unionoidea. Here, we identified and characterized natural pearls formed by Diplodon chilensis, a freshwater clam native to southern South America, using samples obtained from two lakes located in the Chilean Patagonia. Pearls were studied using light and scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. Naturally formed pearls were found in both male and female D. chilensis specimens. Pearls are produced in different shapes, including spherical, ellipsoidal, buttoned, and bumpy, ranging in size from 200 µm to 1.9 mm. The internal microstructure is composed of irregular polygonal tablets, about 0.40 to 0.55 μm in thickness. EDX analysis showed that pearls are composed of calcium carbonate. FTIR and Raman spectra recorded several peaks attributable to the aragonite in pearls of this species, as has been shown in other mollusks. In addition to these results, pearls of different colors are illustrated. [ABSTRACT FROM AUTHOR]

The nanohybrid consists of polyvinyl chloride (PVC) and polyvinylidene fluoride (PVDF) nanostructure network with BaZrO3 and BaTiO3 nanoparticles separately. The mass ratios of PVC-PVDF-BaZrO3/BaTiO3 were chosen to be 60:36:04. The structural morphology of nanohybrid was examined by using Raman spectroscopy and scanning electron microscopy (SEM). The Raman spectroscopy is enabled to explain strong interaction between the nanoparticles and polymer matrix. The PVC-PVDF- 4 mass% BaTiO3 nanohybrid shows high dielectric permittivity, breakdown strength and the energy density as compare to pure polymer matrix. DSC analysis of nanohybrid is attributed the good thermal stability due to crystallization effect in presence of nanoparticles. The findings of present work enable to design the energy storage devices. [ABSTRACT FROM AUTHOR]

The samples ZnO:Mn were prepared using the conventional solid-state technique. To dope them with manganese, we used water solutions of MnSO4 and MnCl2. The properties inherent to both types of the obtained ceramics have been compared. It was found that the former demonstrated nonlinear current-voltage characteristics, whereas those of the latter were, in fact, linear. The analysis of EPR, diffuse reflectance and Raman spectra obtained for prepared ceramics allowed concluding that, in the samples doped with MnSO4, formation of Mn-related phase, namely, ZnMn2O4 spinel occurred at ZnO grain boundaries under sintering. It has been ascertained that a thin layer of this substance separates adjacent ZnO grains, which provides appearance of the back-to-back Schottky barriers at grain boundaries and “varistor behavior” of current-voltage characteristics. [ABSTRACT FROM AUTHOR]

Zinc oxide nanostructures attract considerable attention of researchers due to their unique properties such as electrical conductivity, piezoelectric properties, optical transparency, emission, wide forbidden zone. Zinc oxide nanopowders are obtained by various methods: hydrothermal synthesis, sol-gel method, pyrolysis, chemical precipitation from solution and others. The task of development of low-cost methods of zinc oxide synthesis with high reproducibility is actual. The thermal decomposition method is a controlled relatively inexpensive method that can enable large scale production without the use of complex equipment and expensive materials. In this work, nanostructured ZnO samples were prepared by thermal decomposition of zinc acetate dehydrate at temperatures 400 °C and 700 °C. The influence of such synthesis parameters as duration and temperature on the morphology and structural properties of the obtained samples were investigated. It was found that the morphology of the synthesised ZnO samples significantly depends on the synthesis temperature. The obtained Raman scattering spectra show characteristic peaks of zinc oxide and carbon. An efficient, inexpensive method for the synthesis of zinc oxide nanoparticles with controlled morphology, promising for use as photocatalysts, the basis for the development of sensor devices, is presented. [ABSTRACT FROM AUTHOR]

Titania-based materials are abundant in technological applications, as well as everyday products; however, many of its structure–property relationships are still unclear. In particular, its surface reactivity on the nanoscale has important consequences for fields such as nanotoxicity or (photo)catalysis. Raman spectroscopy has been used to characterize titania-based (nano)material surfaces, mainly based on empirical peak assignments. In the present work, we address the structural features responsible for the Raman spectra of pure, stoichiometric TiO2 materials from a theoretical characterization. We determine a computational protocol to obtain accurate Raman response in a series of anatase TiO2 models, namely, the bulk and three low-index terminations by periodic ab initio approaches. The origin of the Raman peaks is thoroughly analyzed and the structure–Raman mapping is performed to account for structural distortions, laser and temperature effects, surface orientation, and size. We address the appropriateness of previous experimental use of Raman to quantify the presence of distinct TiO2 terminations, and provide guidelines to exploit the Raman spectrum based on accurate rooted calculations that could be used to characterize a variety of titania systems (e.g., single crystals, commercial catalysts, thin layered materials, facetted nanoparticles, etc.). [ABSTRACT FROM AUTHOR]

In this study, molybdenum was used as a binder to prepare sintered polycrystalline diamond (PCD) produced by HPHT technology. The effect of molybdenum as a binder on the comprehensive properties of the PCD was investigated at different temperatures. A detailed characterization of the produced materials demonstrates that molybdenum reacted nearly completely with the carbon of the diamond to form a hybrid matrix (Mo/MoC/Mo 2 C). Microstructural images of the composites evidence a homogeneous distribution of the binder phase and a preserved integrity of the constitutive particles. Based on Raman spectroscopy data, the proximity between the coefficients of thermal expansion (Mo/Diamond) helped maintain composites with a high-quality factor. Regarding the variation in experimental conditions, the increase in temperature was conducive to achieving composites with higher microstructural contiguity. From these results, it can be inferred that molybdenum may be a prospective alternative to be employed as a binding phase in producing well-sintered PCDs. [ABSTRACT FROM AUTHOR]

Though being vitally important in telecommunications and modern technology, the basic optic and especially electro‐optic (EO) properties of ferroelectric LiNbO3 crystal (LN) studied from high‐accuracy first‐principles calculation are still not satisfactory. Herein, the electronic structure and vibrational spectra of LN are calculated by the CRYSTAL program. With a hybrid B3LYP functional, the bandgap of 4.8473 eV, refractive indices of no = 2.2339, ne = 2.1440, and nonlinear optical coefficients of d11 = 2.1 pm V−1, d31 = −4.35 pm V−1, and d33 = −27.2 pm V−1 are obtained. It is found that the phonon vibrations are asymmetric along especially the polar axis and the numerically calculated frequencies are strongly dependent on displacement parameters chosen. By averaging displacements to both the positive and negative directions, the obtained vibrational frequencies show excellent agreement to the measured ones except in the range of 320–370 cm−1 where the assignments of the observed ones are in dispute due to extreme low spectral intensities. Based on the calculated vibrational spectra, the clamped dielectric constants of ε11S=38.62 and ε33S=24.17 and clamped EO coefficients of γ33S = 27.08 pm V−1, γ13S = 9.60 pm V−1, γ11S = −5.14 pm V−1, and γ51S = 16.90 pm V−1 are obtained. [ABSTRACT FROM AUTHOR]

1T-TaS2 has attracted much attention recently due to its abundant charge density wave phases. In this work, high-quality two-dimensional 1T-TaS2 crystals were successfully synthesized by a chemical vapor deposition method with controllable layer numbers, confirmed by the structural characterization. Based on the as-grown samples, their thickness-dependency nearly commensurate charge density wave/commensurate charge density wave phase transitions was revealed by the combination of the temperature-dependent resistance measurements and Raman spectra. The phase transition temperature increased with increasing thickness, but no apparent phase transition was found on the 2~3 nm thick crystals from temperature-dependent Raman spectra. The transition hysteresis loops due to temperature-dependent resistance changes of 1T-TaS2 can be used for memory devices and oscillators, making 1T-TaS2 a promising material for various electronic applications. [ABSTRACT FROM AUTHOR]

Metathesis reactions designed to produce nominally the pseudo-ternary ATl[N(CN)2]2 compounds (A = Li, Na, K, Rb or Cs) either yielded solid solutions or separated pseudo-binary dicyanamides next to the new compounds LiTl[N(CN)2]2 and Tl0.89(1)Cs0.11(1)[N(CN)2]. Tetragonal LiTl[N(CN)2]2 (a = 724.96(2), c = 1411.77(6) pm, Z = 4) is crystallizing isotypically with LiK[N(CN)2]2 in the space group I4/mcm, while orthorhombic Tl0.89(1)Cs0.11(1)[N(CN)2] (a = 858.19(4), b = 654.22(2), c = 738.94(4) pm, Z = 4) adopts the α-K[N(CN)2]-type structure in the space group Pbcm, which Tl[N(CN)2] itself also assumes, with the unique cationic position shared by Tl+ and Cs+ in an approximate 9:1 molar ratio. The Raman spectra of the new compounds are presented and compared to those of Tl[N(CN)2], LiK[N(CN)2]2 and LiRb[N(CN)2]2. [ABSTRACT FROM AUTHOR]