Raman Micro Research Articles

Deterioration-associated microbiome of a modern photographic artwork: the case of Skull and Crossbones by Robert Mapplethorpe

The preservation of cultural heritage, including ancient photographic materials, is of paramount importance in the field of conservation science. In this context, the microbial diversity of ‘Skull and Crossbones’, a 1983 photograph by Robert Mapplethorpe printed on silver gelatine, was assessed. We employed both culture-dependent and culture-independent methods to characterize microbial communities inhabiting this artwork. Vibrational Raman micro spectroscopy and FT-IR spectroscopy were utilized to assess the chemical degradation condition and characterize the chemical components of the silver gelatin print. The combination of molecular sequencing methods (Sanger and HTS approach) and non-invasive vibrational spectroscopy yielded valuable insights into the microbial communities thriving on photographic material and the chemical degradation of the print. Isolated fungal strains were added to the Fungal Collection at the University of Naples Federico II, and their deteriorative potential was investigated by adding substrates, commonly used in canvas photographs to the culture media. These results establish a link between microbial communities colonizing ancient photographic materials, paper decomposition, and the enzymatic patterns of the retrieved microorganisms. This information is invaluable for understanding and addressing biodeterioration progression on valuable works of art, such as historical photographs, which remain understudied.

Synthesis and Morphology Characteristics of New Highly Branched Polycaprolactone PCL.

A simple and efficient method for the synthesis of biodegradable, highly branched polycaprolactone (PCL) is presented. The solvent-free (bulk) reaction was carried out via ring opening polymerization (ROP), catalyzed by tin octanoate Sn(Oct)2, and it employed hyperbranched polyamide (HPPA) as a macro-initiator. The core-shell structure of the obtained products (PCL-HPPA), with the hyperbranched HPPA core and linear PCL chains as shell, was in the focus of the product characterization. 1H nuclear magnetic resonance (1H NMR) and elemental analysis confirmed the covalent incorporation of the HPPA in the products, as well as a high degree of grafting conversion of its amino functional groups. Confocal Raman Micro spectroscopy, and especially Time-of-Flight Secondary Ion Mass Spectrometry, further supported the existence of a core-shell structure in the products. Direct observation of macromolecules by means of cryogenic transmission electron microscopy, as well as gel permeation chromatography (GPC), suggested the existence of a minor 'aggregated' product fraction with multiple HPPA cores, which was attributed to transesterification reactions. Differential scanning calorimetry, as well as X-ray diffraction, demonstrated that the PCL-HPPA polymers displayed a similar degree of crystallinity to linear neat PCL, but that the branched products possessed smaller and less regular crystallites.

Laser Raman micro spectroscopy and high frequency dielectric properties of silica- xerogel loaded with different concentrations of α-Fe2O3

Laser Raman micro spectroscopy and high frequency dielectric properties of silica- xerogel loaded with different concentrations of α-Fe2O3

Laser Raman micro spectroscopy and high frequency dielectric properties of silica- xerogel loaded with different concentrations of α-Fe2O3

Laser Raman micro spectroscopy and high frequency dielectric properties of silica- xerogel loaded with different concentrations of α-Fe2O3

Raman microspectroscopy based TNM staging and grading of breast cancer

The tumor-node-metastasis (TNM) system is the most common way that doctors determine the anatomical extent of cancer on the basis of clinical and pathological criteria. In this study, a spectral histopathological study has been carried out to bridge Raman micro spectroscopy with the breast cancer TNM system. A total of seventy breast tissue samples, including healthy tissue, early, middle, and advanced cancer, were investigated to provide detailed insights into compositional and structural variations that accompany breast malignant evolution. After evaluating the main spectral variations in all tissue types, the generalized discriminant analysis (GDA) pathological diagnostic model was established to discriminate the TNM staging and grading information. Moreover, micro-Raman images were reconstructed by K-means clustering analysis (KCA) for visualizing the lobular acinar in healthy tissue and ductal structures in all early, middle and advanced breast cancer tissue groups. While, univariate imaging techniques were adapted to describe the distribution differences of biochemical components such as tryptophan, β-carotene, proteins, and lipids in the scanned regions. The achieved spectral histopathological results not only established a spectra-structure correlations via tissue biochemical profiles but also provided important data and discriminative model references for in vivo Raman-based breast cancer diagnosis.

Skin Care Product Rich in Antioxidants and Anti-Inflammatory Natural Compounds Reduces Itching and Inflammation in the Skin of Atopic Dermatitis Patients.

The atopic dermatitis (AD) complex pathogenesis mechanism reveals marked changes of certain signaling factors as well as some morphological alterations in the epidermis. Reduced resilience against environmental factors and oxidative stress often makes the treatment with corticosteroids or tacrolismus ointments indispensable. In view of the correlation between oxidative stress and AD pathological factors, antioxidants can be incorporated into AD management strategies. This study investigates a curly kale, apple and green tea-containing natural extract rich in antioxidants for its effects on signaling inflammatory molecules and skin barrier enhancement in human epidermal keratinocytes- (NHEKs) based cell assays. Furthermore, the skin penetration on porcine ears was measured ex vivo using Raman micro spectroscopy. Finally, in a double-blind half-side, placebo-controlled clinical study, the effects of a formulation containing this extract were analyzed for the influence of lesion severity, epidermal barrier function, and pruritus in mild to moderately AD patients. Summarizing our results: The extract reduces expression of inflammatory cytokines in keratinocytes and increases barrier-related molecules. The verum formulation with a very high antioxidant capacity used in AD patients with mild to moderate lesions reduces itching, local SCORAD, and improves barrier function and the hydration of skin lesions.

Dimensional reduction based on peak fitting of Raman micro spectroscopy data improves detection of prostate cancer in tissue specimens.

.Significance: Prostate cancer is the most common cancer among men. An accurate diagnosis of its severity at detection plays a major role in improving their survival. Recently, machine learning models using biomarkers identified from Raman micro-spectroscopy discriminated intraductal carcinoma of the prostate (IDC-P) from cancer tissue with a detection accuracy and differentiated high-grade prostatic intraepithelial neoplasia (HGPIN) from IDC-P with a accuracy.Aim: To improve the classification performance of machine learning models identifying different types of prostate cancer tissue using a new dimensional reduction technique.Approach: A radial basis function (RBF) kernel support vector machine (SVM) model was trained on Raman spectra of prostate tissue from a 272-patient cohort (Centre hospitalier de l’Université de Montréal, CHUM) and tested on two independent cohorts of 76 patients [University Health Network (UHN)] and 135 patients (Centre hospitalier universitaire de Québec-Université Laval, CHUQc-UL). Two types of engineered features were used. Individual intensity features, i.e., Raman signal intensity measured at particular wavelengths and novel Raman spectra fitted peak features consisting of peak heights and widths.Results: Combining engineered features improved classification performance for the three aforementioned classification tasks. The improvements for IDC-P/cancer classification for the UHN and CHUQc-UL testing sets in accuracy, sensitivity, specificity, and area under the curve (AUC) are (numbers in parenthesis are associated with the CHUQc-UL testing set): (), (), (6%), () with respect to the current best models. Discrimination between HGPIN and IDC-P was also improved in both testing cohorts: (), (), (), (). While no global improvements were obtained for the normal versus cancer classification task [ (), (), (), ()], the AUC was improved in both testing sets.Conclusions: Combining individual intensity features and novel Raman fitted peak features, improved the classification performance on two independent and multicenter testing sets in comparison to using only individual intensity features.

Effect of defects on the band gap and photoluminescence emission of Bi and Li co-substituted barium strontium titanate ceramics

Since the discovery of an effective role for defects in improving the performance of ceramic materials in practical application, investigation of defects and their impact on the development of optical properties in condensed matter physics have received widespread attention. In this work we synthesized a lead free (Ba0·60Sr0.40)(1-x)(Bi,Li)xTiO3 (BST6:BLx%); (0%≤x ≤ 8%) ceramics using a conventional solid-state reaction method. X-ray diffraction patterns along with Rietveld refinement, Micro-Raman (MR) spectroscopy, X-ray Photoelectron Spectroscopy (XPS), UV–visible, Electron Spin Resonance (ESR) and photoluminescence (PL) measurements are utilized to characterize these ceramics. XRD, and Raman analysis have proven cubic phase symmetry with a contraction in bond length as the Bi and Li concentrations increased. XPS and ESR results confirm the presence of Ti3+ surface defects (TSD) and oxygen vacancies (VO) on the co-substituted samples sintered at high temperature. The optical results show a decrease in the bandgap energy from 3.14 eV to 2.76 eV and a wide-PL band emission on the green band, caused by recombination of the radiative free electrons and holes trapped around the surface oxygen vacancies. Defect levels created within the bandgap might act as recombination centres, and this can give the possibility of using BST6:BLx as a green light emission source in future practical applications.

Raman geobarometry of quartz inclusions in eclogitic garnet constrains the metamorphic evolution and exhumation of the Sumdo oceanic slab in Tibet

Due to the high density at mantle depths, subducted oceanic crust rarely exhumes to the surface of Earth, making it challenging to determine the evolution and dynamic behavior of oceanic crust. The Sumdo eclogite-bearing metamorphic belt, located between the north and south Lhasa terranes in Tibet, is a natural laboratory for studying the metamorphic evolution of oceanic eclogites. We combined phase equilibrium modeling with detailed petrological investigations for the newly discovered Xilang eclogite from this belt and obtained near-peak metamorphic conditions of 539 °C at 1.84 GPa and a steep exhumation P–T path. These values are much lower than published for the other areas of this belt. Quartz inclusions sealed in garnet from high-pressure rocks are known to preserve residual pressures during exhumation, which can be used to reexamine the peak metamorphic conditions of eclogites in the Sumdo metamorphic belt. We analyzed quartz from three different areas in the belt, including Xilang, Jilang, and Xindaduo, with laser Raman micro spectroscopy. Xilang eclogite preserved the highest residual pressure of 0.53 ± 0.07 GPa in the quartz stability field. A systematic comparison of the residual pressures of different eclogites revealed that not only the peak metamorphic conditions but also the exhumation rate of the host rocks controlled the residual pressure. Hence, the Xilang eclogite may record lower peak P–T conditions, because it exhumed differently than the eclogites from the other areas in the Sumdo metamorphic belt. Combined with numerical modeling, the residual pressures obtained by Raman spectroscopy may be a new way to compare the metamorphic conditions of eclogites and to obtain geochronological information in addition to isotopic investigations.

Two-dimensional ReS2 : Solution to the unresolved queries on its structure and inter-layer coupling leading to potential optical applications

Over the last few years, ReS2 has generated a myriad of unattended queries regarding its structure, the concomitant thickness dependent electronic properties and apparently contrasting experimental optical response. In this work, with elaborate first-principles investigations, using density functional theory (DFT) and time-dependent DFT (TDDFT), we identify the structure of ReS2, which is capable of reproducing and analyzing the layer-dependent optical response. The theoretical results are further validated by an in-depth structural, chemical, optical and optoelectronic analysis of the large-area ReS2 thin films, grown by chemical vapor deposition (CVD) process. Micro-Raman (MR), X-ray photoelectron spectroscopy (XPS), cross-sectional transmission electron microscopy (TEM) and energy-dispersive X-ray analysis (EDAX) have enabled the optimization of the uniform growth of the CVD films. The correlation between the layer-dependent optical and electronic properties of the excited states was established by static photoluminescence (PL) and transient absorption (TA) measurements. Sulfur vacancy-induced localized mid-gap states render a significantly long life-time of the excitons in these films. The ionic gel top-gated photo-detectors, fabricated from the as-prepared CVD films, exhibit a large photo-response of ~ 5 A/W and a remarkable detectivity of ~ 1011 Jones. The outcome of the present work will be useful to promote the application of vertically grown large-area films in the field of optics and opto-electronics.

Photocatalytic performance of β-Ag2MoO4 microcrystals at different experimental conditions

In this present work, we report the photocatalytic activity of microcrystals of silver molybdate (β-Ag2MoO4) synthesized at 120 °C for 2 h by hydrothermal method. These microcrystals have been structurally characterized by X-ray diffraction (XRD), Rietveld refinement and micro-Raman (MR). The optical properties and the structure of the band gap were studied using diffuse reflectance spectroscopy of UV–vis (UV–vis) and photoluminescence (PL). The morphology and semiquantitative analysis of elements were investigated by field emission scanning electron microscopy (FE-SEM) images. The photocatalytic properties of these microcrystals have been investigated in the degradation of rhodamine B (RhB) and methyl orange (MO) dyes under UV-light. XRD patterns, Rietveld refinement data and Raman spectrum indicate that all microcrystals exhibit spinel-type cubic structure with space group of Fd3¯m and point group of symmetry O7h composed by tetrahedral [MoO4] and distorted octahedral [AgO6] clusters. The optical band gap found was Egap =3.30 eV for β-Ag2MoO4 microcrystals, associated with the indirect allowed electronic transitions. FE-SEM images have revealed that microcrystals have potato-like morphology. The photoluminescent properties (PL) verified can be explained by the distortions of the clusters present in the structure of β-Ag2MoO4 microcrystals. Moreover, these microcrystals exhibit high photocatalytic performance at pH > 8. Where, the photo-induced holes (h+) are one of the main reactive species involved in the degradation of RhB and MO dyes.

Geology, fluid inclusions, and H–O–S–Pb isotopes of the Chigou porphyry Cu deposit in Southern Qinling, central China: Implication for ore genesis

The Chigou porphyry Cu deposit is located in eastern segment of the Southern Qinling metallogenic belt, on the southern margin of the Central China Orogenic Belt. Copper mineralization is associated with quartz diorite, quartz diorite porphyry and granite porphyry, and occurs as veins, veinlets, disseminations, or veinlet-disseminations within host porphyries. Ore-forming process could be divided into three stages: stage I quartz + K-feldspar + pyrite ± chalcopyrite, stage II quartz + chlorite + chalcopyrite ± molybdenite and stage III quartz + calcite + pyrite. Four types of fluid inclusions (FIs) were distinguished in quartz-bearing veins, including vapor-rich two-phase (V-type), liquid-rich two-phase (L-type), hypersaline (H-type), and CO2-rich (C-type) inclusions. The FIs were homogenized at temperatures of 330–473 °C for stage I, 174–345 °C for stage II, and 128–272 °C for stage III, with corresponding salinities of 3.8–53.6 wt% NaCl equiv., 1.4–15.1 wt% NaCl equiv., and 0.4–7.7 wt% NaCl equiv., respectively. Hydrogen and oxygen isotope data indicate that the ore-forming fluids have a dominant magma signature and were diluted by meteoric water during the late stage. Chalcopyrite and pyrite from different stages record a narrow range of δ34S values from −0.2 to −2‰, consistent with the sulfur isotopic values of typical magmatic-hydrothermal system. Chalcopyrite has similar 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios to those of porphyry intrusions. All stable and radiogenic isotope results reveal that the ore-forming components (i.e. metal and sulfur) were sourced from a magmatic reservoir with some crustal materials. Laser Raman micro spectroscopy data and fluid inclusion analytical results suggest that the Chigou deposit was formed by an initially high- to intermediate-temperature, high-oxygen fugacity (fO2) and CO2-rich fluid system at an estimated depth of 0.7–2.1 km. Decreases in temperature and fO2 as well as fluid boiling were critical factors controlling sulfide precipitation at Chigou.

Application of Raman Micro Spectroscopy and Micro-FTIR Mapping in the Bio-Hydrometallurgy of Copper Sulfide-Minerals

Application of Raman Micro Spectroscopy and Micro-FTIR Mapping in the Bio-Hydrometallurgy of Copper Sulfide-Minerals

Mineral inclusions in diamonds from Chapada Diamantina, Bahia, Brazil: a Raman spectroscopic characterization

Abstract The Chapada Diamantina, located in the central region of the State of Bahia, is of important historical significance due to its diamond occurrences. Discovered in the nineteenth century, comprehensive research about the regional diamonds and their origins are still limited, demanding more investigation in the matter. Looking for insights about their genesis, mineral inclusions in 23 alluvial diamonds from 4 garimpos located in the Chapada Diamantina were analyzed through the use of Raman micro spectroscopy. Additionally, the characteristics of nitrogen aggregation of the host diamonds were measured using Fourier-transform infrared spectroscopy (FTIR). The diamonds from Chapada Diamantina consist mainly of well-formed crystals, with dominant dodecahedral habits, characterized by faint to very light yellow body colors, typically with green and brown radiation spots on their surface. The main surface textures observed are related to processes that took place in the late stage resorption and during the residence of the diamonds in placer environments. The diamonds are predominantly type IaAB, with a significant occurrence of poorly aggregated nitrogen (Type IaA diamond). The main mineral assemblages of the studied peridotitic inclusions refer to a harzburgitic paragenesis.

Antiangiogenic evaluation of ZnWO4 nanoparticles synthesised through microwave-assisted hydrothermal method

Angiogenesis, the complex process of formation of new blood vessels from pre-existing blood vessels, which involves the participation of several pro- and anti-angiogenic factors, is implicated in many physiological and pathological conditions. Nanoparticle-based anti-angiogenic activity at the tumour tissue, harnessed by the Enhanced Permeability and Retention Effect (EPR effect), could potentially become a breakthrough therapy to halt tumour progression. Herein, we evaluate the anti-angiogenic effect of ZnWO4 nanoparticles (NPs). The nanoparticles were obtained by microwave-assisted hydrothermal synthesis (MAHS) at 120 °C for 60 min and were structurally characterised by X-ray diffraction (XRD) and micro-Raman (MR) spectroscopy. The mean size and polydispersity index were estimated by Zeta potential analysis. The XRD analysis revealed structural organisation at a long-range order, with an average crystallite size of around 3.67 nm, while MR revealed short-range order for ZnWO4. The anti-angiogenic potential of zinc tungstate nanoparticles was investigated through the chorioallantoic membrane assay (CAM) using fertilised chicken eggs. We demonstrate, in an unprecedented way, that nanocrystalline ZnWO4 NPs obtained by MAHS, at low reaction temperatures, showed excellent anti-angiogenic properties even at low concentrations. The ZnWO4 NPs were further evaluated for its cytotoxicity in vitro.

Flexible wire-based electrodes exploiting carbon/ZnO nanocomposite for wearable supercapacitors

A facile and scalable approach is here proposed to fabricate fiber-shaped electrodes and their integration into wearable supercapacitors. Copper wires were used as axial current collector and covered by dip coating with a carbon-based slurry. A gel electrolyte was used both as ionic conductor and separator between the two parallel wire-electrodes. The decoration of the carbon-based active material with ZnO nanoparticles was investigated in order to boost the supercapacitors performance exploiting the pseudocapacitive response of this wide band-gap semiconductor. Composites of ZnO/graphite with different wt.% ZnO (such as 1, 5, 10, 20% of ZnO nanoparticles) were prepared. X-ray powder diffraction and Raman micro spectroscopy served as phase-analytical methods. Field emission scanning electron microscopy technique was used for morphology characterization of the prepared samples. The electrical characterization of the devices showed excellent results both in terms of specific capacitance and cycling and bending stability. The ease of the proposed process can allow its rapid integration in a large-scale production for efficient wearable supercapacitors.

Chemical Interaction Analysis of an Adhesive Containing 10-Methacryloyloxydecyl Dihydrogen Phosphate (10-MDP) With the Dentin in Noncarious Cervical Lesions

The purpose of this study was to evaluate the chemical bonds of a self-etch 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) adhesive to natural noncarious cervical lesions (NCCLs) and compare them with those occurring in sclerotic dentin in artificially prepared defects (APDs). Four human teeth with natural NCCLs on the buccal surface were selected. Artificial defects matching the natural lesions were prepared on the lingual surface of the same teeth serving as control. Micro-Raman (MR) spectroscopy was used to quantify mineral content in natural NCCLs and in APDs. Fourier transform infrared-photoacoustic spectroscopy (FTIR-PAS) readouts were taken before and after adhesive application to analyze the protein matrix/mineral (M:M) ratio and chemical interactions between 10-MDP adhesive and dentin. The MR and FTIR-PAS spectra collected from natural NCCLs demonstrated a larger area of the band (961 cm-1, PO4) and lower M:M ratio, respectively, characterizing a hypermineralized dentin, compared with APDs. FTIR-PAS demonstrated emergence of a peak (1179 cm-1, P=O) in spectra after adhesive treatment, demonstrating a more intense chemical interaction in natural NCCLs. The results demonstrated that chemical bonding of 10-MDP adhesive to natural NCCLs is more intense, due to the hypermineralized surface, and suggest that it is unnecessary to remove the hypermineralized layer with burs, as this may decrease the chemical bonding potential of 10-MDP.

Differentiating responses of lung cancer cell lines to Doxorubicin exposure: in vitro Raman micro spectroscopy, oxidative stress and bcl-2 protein expression.

The potential of Raman micro spectroscopy as an in vitro, non-invasive tool for clinical applications has been demonstrated in recent years, specifically for cancer research. To further illustrate its potential as a high content and label free technique, it is important to show its capability to elucidate drug mechanisms of action and cellular resistances. In this study, cytotoxicity assays were employed to establish the toxicity profiles for 24hr exposure of lung cancer cell lines, A549 and Calu-1, to the commercially available drug, doxorubicin (DOX). Raman spectroscopy, coupled with Confocal Laser Scanning Microscopy and Flow Cytometry, was used to track the DOX mechanism of action, at a subcellular level, and to study the mechanisms of cellular resistance to DOX. Biomarkers related to the drug mechanism of action and cellular resistance to apoptosis, namely reactive oxygen species (ROS) and bcl-2 protein expression, respectively, were also measured and correlated to Raman spectral profiles. Calu-1 cells are shown to exhibit spectroscopic signatures of both direct DNA damage due to intercalation in the nucleus and indirect damage due to oxidative stress in the cytoplasm, whereas the A549 cell line only exhibits signatures of the former mechanism of action. PCA of nucleolar, nuclear and cytoplasmic regions of A549 and Calu-1 with corresponding loadings of PC1 and PC2.

Understanding the formation and growth of Ag nanoparticles on silver chromate induced by electron irradiation in electron microscope: A combined experimental and theoretical study

Ag2CrO4 microcrystals were synthesized using the co-precipitation method. These microcrystals were characterized through X-ray diffraction (XRD) with Rietveld analysis, field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) with energy-dispersive spectroscopy (EDS), micro-Raman (MR). XRD patterns and Rietveld refinement data showed that the material exhibits an orthorhombic structure without any deleterious phases. FE-SEM and TEM micrographs revealed the morphology and the growth of Ag nanoparticles on Ag2CrO4 microcrystals during electron beam irradiation. These events were directly monitored in real-time. Their optical properties were investigated using ultraviolet-visible (UV–vis) diffuse reflectance spectroscopy that allowed the calculation of the optical band gap energy. Theoretical analyses based on the density functional theory level indicate that the incorporation of electrons is responsible for structural modifications and formation of defects on the [AgO6] and [AgO4] clusters, generating ideal conditions for the growth of Ag nanoparticles.

Growth Rate and Morphology of a Single Calcium Carbonate Crystal on Polysulfone Film Measured with Time Lapse Raman Micro Spectroscopy

The growth of single, self- nucleated calcium carbonate crystals on a polysulfone (PSU) film was investigated with high resolution, time lapse Raman imaging. The Raman images were acquired on the interface of the polymer with the crystal. The growth of crystals could thus be followed in time. PSU is a polymer that is used as a membrane material in water cleaning technology. The intensity of the Raman band at the position of 1086 cm-1, which is due to the symmetric stretching of the C-O bonds in the carbonate group of calcite was used to translate the number of CO3 2- ions in a crystal to the growth in time. The growth rate of single crystals of calcium carbonate on a surface was obtained from successive Raman images. We are presenting for the first time time-lapse Raman images of single crystal growth as a direct method to determine a crystal growth rate on an industrially relevant membrane material, like polysulfone.