Raman Spectroscopy Characterization of Amorphous Coke Generated in Industrial Processes.
Ontology highlight
ABSTRACT:
SUBMITTER: Zhang CC
PROVIDER: S-EPMC8792926 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Exploring highly surface-enhanced Raman scattering (SERS)-active semiconductors is urgently required for practical applications. Here, with the guidance of theoretical calculations, amorphous rhodium sulfide microbowls with high enhancement factor (1 × 105) and low limit of detection (10-7 M) for rhodamine 6G are successfully developed. This remarkable sensitivity is attributed to quasi-resonance Raman effect and multiple light scattering. The first-principles calculations show that the energy gap of 4-nitrobenzenethiol adsorbed on Rh3S6 is greatly decreased by shifting its lowest unoccupied molecular orbital (LUMO) energy level close to the LUMO of Rh3S6, enabling quasi-resonance Raman effect by visible light. The finite-difference time-domain simulations demonstrate the efficient photon trapping ability enabled by multiple light scattering. The optimum wavelength of ?633 nm for SERS is predicted in simulations and confirmed in experiments. Our results provide both a deep insight of the photo-driven charge transfer process and an important guidance for designing SERS-active semiconductors.
| S-EPMC6260454 | biostudies-literature
Project description:Accurately identifying the local structural heterogeneity of complex, disordered amorphous materials such as amorphous silicon is crucial for accelerating technology development. However, short-range atomic ordering quantification and nanoscale spatial resolution over a large area on a-Si have remained major challenges and practically unexplored. We resolve phonon vibrational modes of a-Si at a lateral resolution of <60 nm by tip-enhanced Raman spectroscopy. To project the high dimensional TERS imaging to a two-dimensional manifold space and categorize amorphous silicon structure, we developed a multiresolution manifold learning algorithm. It allows for quantifying average Si-Si distortion angle and the strain free energy at nanoscale without a human-specified physical threshold. The multiresolution feature of the multiresolution manifold learning allows for distilling local defects of ultra-low abundance (< 0.3%), presenting a new Raman mode at finer resolution grids. This work promises a general paradigm of resolving nanoscale structural heterogeneity and updating domain knowledge for highly disordered materials.
| S-EPMC7835247 | biostudies-literature
Project description:Macrophages are important cells of the innate immune system that play many different roles in host defense, a fact that is reflected by their polarization into many distinct subtypes. Depending on their function and phenotype, macrophages can be grossly classified into classically activated macrophages (pro-inflammatory M1 cells), alternatively activated macrophages (anti-inflammatory M2 cells), and non-activated cells (resting M0 cells). A fast, label-free and non-destructive characterization of macrophage phenotypes could be of importance for studying the contribution of the various subtypes to numerous pathologies. In this work, single cell Raman spectroscopic imaging was applied to visualize the characteristic phenotype as well as to discriminate between different human macrophage phenotypes without any label and in a non-destructive manner. Macrophages were derived by differentiation of peripheral blood monocytes of human healthy donors and differently treated to yield M0, M1 and M2 phenotypes, as confirmed by marker analysis using flow cytometry and fluorescence imaging. Raman images of chemically fixed cells of those three macrophage phenotypes were processed using chemometric methods of unmixing (N-FINDR) and discrimination (PCA-LDA). The discrimination models were validated using leave-one donor-out cross-validation. The results show that Raman imaging is able to discriminate between pro- and anti-inflammatory macrophage phenotypes with high accuracy in a non-invasive, non-destructive and label-free manner. The spectral differences observed can be explained by the biochemical characteristics of the different phenotypes.
| S-EPMC9821063 | biostudies-literature
Project description:Formamide has been recognized in the literature as a key species in the formation of the complex molecules of life, such as nucleobases. Furthermore, several studies reported the impact of mineral phases as catalysts for its decomposition/polymerization processes, increasing the conversion and also favoring the formation of specific products. Despite the progresses in the field, in situ studies on these mineral-catalyzed processes are missing. In this work, we present an in situ UV-Raman characterization of the chemical evolution of formamide over amorphous SiO2 samples, selected as a prototype of silicate minerals. The experiments were carried out after reaction of formamide at 160 °C on amorphous SiO2 (Aerosil OX50) either pristine or pre-calcined at 450 °C, to remove a large fraction of surface silanol groups. Our measurements, interpreted on the basis of density functional B3LYP-D3 calculations, allow to assign the spectra bands in terms of specific complex organic molecules, namely, diaminomaleonitrile (DAMN), 5-aminoimidazole (AI), and purine, showing the role of the mineral surface on the formation of relevant prebiotic molecules.
| S-EPMC7287731 | biostudies-literature
Project description:The interaction of graphene with gold nanoparticles is investigated using transmission electron microscopy. We observe gold-nanoparticle-mediated etching of graphene flakes, often leading to hole formation. Further, using a combination of high-angle annular dark field imaging and electron energy loss spectroscopy, we highlight that the catalytic effects of gold nanoparticles on graphene lead to the formation of amorphous carbon layers. From the extracted diffractograms, we observe regions with diffraction halos as well as some regions with a weak tetrahedral motif. Using independently performed Raman measurements, we confirm the presence of tetrahedral amorphous carbon as well as mixed graphitic-amorphous regions. For the amorphous carbon regions with mixed sp2-sp3 states, the Raman G peak is red-shifted to 1564 cm-1 and an I D/I G ratio of 0.63 indicates less than 20% sp3 content. For the tetrahedral amorphous carbon regions, we observe that the Raman G peak is at 1580 cm-1, close to that of monolayer graphene. However, there is no Raman D peak, i.e., I D/I G = 0, which indicates close to 100% sp3 content. The translation of the Raman G peak location and the I D/I G ratios is on par with the amorphization trajectory analysis of Ferrari and Robertson (Phys. Rev. B: Condens. Matter Mater. Phys., 2000, 61, 14095) and validates the conversion route of graphite to amorphous carbon to tetrahedral amorphous carbon. The presented method provides a promising pathway for creating defect-induced amorphous carbon at room temperature, which has a broader impact on the electronics and semiconductor industries.
| S-EPMC11318520 | biostudies-literature
Project description:In this study, Raman spectroscopy has been utilized to characterize buffalo, cow and goat fat samples by using laser wavelengths at 532 and 785 nm as excitation sources. It has been observed that Raman spectra of cow fats contain beta-carotene at 1006, 1156 and 1520 cm-1, which are absent in buffalo and goat fats. The Raman bands at 1060, 1080, 1127 and 1440 cm-1 represent the saturated fatty acids, and their concentration is found relatively higher in buffalo fats than cow and goat. Similarly, the Raman band at 1650 cm-1 represent conjugated linoleic acid (CLA) which shows its relatively higher concentration in goat fats than cow and buffalo. The Raman band at 1267 cm-1 represent unsaturated fatty acids, which shows its relatively higher concentration in goat fats than cow and buffalo. The Raman bands at 838, 870 and 1060 cm-1 depict relatively higher concentration of vitamin D in buffalo fats than cow and goat. Principal component analysis has been applied to highlight the differences among three fat types which based upon the concentration of fatty acids, CLA and vitamin D.
| S-EPMC7813940 | biostudies-literature
Project description:Graphene has extraordinary mechanical and electronic properties, making it a promising material for membrane-based nanoelectromechanical systems (NEMS). Here, chemical-vapor-deposited graphene is transferred onto target substrates to suspend it over cavities and trenches for pressure-sensor applications. The development of such devices requires suitable metrology methods, i.e., large-scale characterization techniques, to confirm and analyze successful graphene transfer with intact suspended graphene membranes. We propose fast and noninvasive Raman spectroscopy mapping to distinguish between free-standing and substrate-supported graphene, utilizing the different strain and doping levels. The technique is expanded to combine two-dimensional area scans with cross-sectional Raman spectroscopy, resulting in three-dimensional Raman tomography of membrane-based graphene NEMS. The potential of Raman tomography for in-line monitoring is further demonstrated with a methodology for automated data analysis to spatially resolve the material composition in micrometer-scale integrated devices, including free-standing and substrate-supported graphene. Raman tomography may be applied to devices composed of other two-dimensional materials as well as silicon micro- and nanoelectromechanical systems.
| S-EPMC5345116 | biostudies-literature
Project description:Background and study aims
Bowel cancer is one of the commonest cancers worldwide. Earlier detection causes better outcomes for patients and longer survival. Symptoms of bowel cancer are non-specific and are shared by harmless bowel disorders. It is a challenge for doctors in general practice to diagnose bowel cancer and many symptomatic patients are sent to hospital for tests to rule it out. This is normally a colonoscopy, which is expensive, uncomfortable and can be harmful. The current approach to diagnosis causes great anxiety in patients waiting for these tests and is not a prudent approach to diagnosis. To allow earlier diagnosis by GPs we have studied whether a newly designed blood test taken in primary care is accurate and effective in patients with bowel symptoms that could be linked with cancer. This would benefit a large number of patients who are concerned about their bowel symptoms without the need for referral to hospital. It could also lead to diagnosis of bowel cancer at an earlier stage improving survival in the longer term. The aim of this study is to use a newly developed blood test for bowel cancer in primary care to achieve an earlier diagnosis. This would allow more timely appropriate treatment both for patients diagnosed with bowel cancer and those who are cancer free.
Who can participate?
Adults aged 50 years and older who have symptoms of bowel cancer.
What does the study involve?
Participants are randomly allocated to one of two groups. Those in the first group have their Raman spectroscopy blood test done immediately and those in the second grou have their sample tested after they’ve had a diagnosis. The amount of participants who are referred on the USC pathway from each group are assessed after 12 months.
| 2416539 | ecrin-mdr-crc
Project description:Raman spectroscopy for pathogen detection and antibiotic resistance identification
| PRJEB59025 | ENA
Project description:Multi-excitation Raman Spectroscopy Complements Whole Genome Sequencing for Rapid Detection of Bacterial Infection and Resistance in WHO Priority Pathogens
| PRJEB59061 | ENA