Confocal Laser Raman Spectroscopy Research Articles

Fast fabrication of superhydrophobic Ti-6Al-4V surface using Q-switched nanosecond pulsed laser at 1064 nm and cyclohexane

Superhydrophobic and superhydrophilic surfaces are attracting significant attention in fundamental and applied research. This study fabricated the micro/nanostructure with a Q-switched nanosecond pulsed laser on the Ti-6Al-4V surface. Three laser-generated surface topographies on titanium were produced based on three different pitch sizes (51 μm, 34 μm, and 29 μm). The laser textured surfaces (LTS) were studied in terms of both structure evolution and chemical composition using Field Emission Scanning Electron Microscopy (FE-SEM), Optical Microscopy (OM), Confocal Laser Scanning Microscopy (CLSM), Raman Spectroscopy, and X-ray Diffractometer (XRD). 29 μm pitch displayed the lowest water contact angle of 18.5° and surface roughness of 0.5 μm. This structure was further treated with cyclohexane at different temperatures. The best sample reached superhydrophobicity with a maximum water contact angle of 155.1° immediately after being treated with cyclohexane at the low temperature of 70 °C for 2 h, while the raw surface, for comparison, showed no change in hydrophobicity after being treated with cyclohexane under the same condition. Thus showing clear evidence of a combined effect between LTS and post-treatment. The surface features were assessed to explain the underlying process.

Advanced optical imaging techniques for bladder cancer detection and diagnosis: a systematic review.

To systematically assess the current available literature concerning advanced optical imaging methods for the detection and diagnosis of bladder cancer (BCa), focusing particularly on the sensitivity and specificity of these techniques. First a scoping search was performed to identify all available optical techniques for BCa detection and diagnosis. The optical imaging techniques used for detecting BCa are: the Storz professional image enhancement system (IMAGE1 S), narrow-band imaging (NBI), photoacoustic imaging (PAI), autofluorescence imaging (AFI), photodynamic diagnosis (PDD), and scanning fibre endoscopy (SFE). The staging and grading techniques for BCa are: optical coherence tomography (OCT), confocal laser endomicroscopy (CLE), Raman spectroscopy, endocytoscopy, and non-linear optical microscopy (NLO). Then a systematic literature search was conducted using MEDLINE, EMBASE and Web of Science from inception to 21 November 2023. Articles were screened and selected by two independent reviewers. Inclusion criteria were: reporting on both the sensitivity and specificity of a particular technique and comparison to histopathology, and in the case of a detection technique comparison to white light cystoscopy (WLC). Out of 6707 articles, 189 underwent full-text review, resulting in 52 inclusions. No articles met criteria for IMAGE1 S, PAI, SFE, Raman spectroscopy, and endocytoscopy. All detection techniques showed higher sensitivity than WLC, with NBI leading (87.8-100%). Overall, detection technique specificity was comparable to WLC, with PDD being most specific (23.3-100%). CLE and OCT varied in sensitivity and specificity, with OCT showing higher specificity for BCa diagnosis, notably for carcinoma in situ (97-99%) compared to CLE (62.5-81.3%). NLO demonstrated high sensitivity and specificity (90-97% and 77-100%, respectively) based on limited data from two small ex vivo studies. Optical techniques with the most potential are PDD for detecting and OCT for staging and grading BCa. Further research is crucial to validate their integration into routine practice and explore the value of other imaging techniques.

Characterization and Comparison of WO3/WO3-MoO3 and TiO2/TiO2-ZnO Nanostructures for Photoelectrocatalytic Degradation of the Pesticide Imazalil.

Tungsten oxide (WO3) and zinc oxide (ZnO) are n-type semiconductors with numerous applications in photocatalysis. The objective of this study was to synthesize and characterize different types of nanostructures (WO3, WO3-Mo, TiO2, and TiO2-ZnO) for a comparison of hybrid and pure nanostructures to use them as a photoanodes for photoelectrocatalytic degradation of emerging contaminants. With the aim of comparing the properties of both samples, field emission scanning electron microscopy (FE-SEM) and confocal laser-Raman spectroscopy were used to study the morphology, composition, and crystallinity, respectively. Electrochemical impedances, Mott-Schottky, and water splitting measurements were performed to compare the photoelectrochemical properties of photoanodes. Finally, the photoelectrocatalytic degradation of the pesticide Imazalil was carried out with the best optimized nanostructure (TiO2-ZnO).

Oxygen Desorption by Graphene-Based Carbon Films Obtained Through Sublimation

Background: Nanocarbon materials are known as highly sensitive gas sensors when compared to common solid-state sensors. This manuscript discusses graphene-based carbon films as materials for a gas sensor operating at near room temperature. Methods: The structural characteristics of graphene-based carbon films on In2O3- and ITO- coated substrates were studied by confocal laser microscopy, SEM, and Raman spectroscopy. Microwave conductivity was measured by using a λ/4 coaxial resonator based on a symmetric two-wire line in the frequency range 0.65 - 1.2 GHz and the temperature range 290-360 K. Results: The results obtained showed that films on In2O3 - and ITO-coated substrates desorb oxygen from the various structural levels of graphene-based carbon, such as crystalline contacts between globular nanoparticles and distorted graphene fragments. A correlation between the size of nanoparticles in films and the desorption temperature was also revealed. Conclusion: Our studies have shown that thin films of natural graphene-based carbon are promising as gas sensors. The possibility of varying characteristic oxygen desorption temperatures on different substrates is discussed.

The development of a joint neural network to the Raman spectroscopy identification of stamp‐pad ink brands and aging

AbstractThe identification of seal authenticity is an important part of document inspection. Confocal laser Raman spectroscopy combined with convolutional neural (CNN) and recurrent neural (RNN) networks was used to distinguish red stamp‐pad ink of different brands and aging. A total of 536 spectral samples from 16 brands were collected in this study and 53,600 amplification data samples were obtained by adding noise. The joint neural network has significant classification performance compared to partial least squares (PLS) discriminant and common CNN. In the three kinds of stamp‐pad inks, photosensitive, atomic, and common, the recognition rate for different brands and aging both reached 100%.

Genesis of Silica‐phosphatic Nodules with Small Shelly Fossils Preserved in the Lowermost Cambrian of South China

AbstractSilica‐phosphatic nodules are abundant in black shales of the Yanjiahe Formation in the Three Gorges Area of South China, which is correlated to the Fortunian Stage, Terreneuvian Series, Cambrian System. The nodules are rich in small shelly fossils and hence attract the attention of numerous paleontologists and sedimentary geologists. However, the genesis of the nodules and the preservation of the small shelly fossils are poorly understood. Here we analyze morphological, structural, mineralogical and chemical features of the nodules in multiscale using a combination of micro‐X‐ray fluorescence spectroscopy, X‐ray diffraction, scanning electron microscopy and confocal laser Raman spectroscopy. Results reveal that nodules are concentric in chemical and mineralogical compositions, comprising a silica‐phosphatic core encrusted sequentially by a phosphatic zone, a siliceous zone and a very thin pyrite outer rim. The black shales hosting the nodules demonstrate a laminated texture of alternating clayey and silty laminae, which were respectively deposited in sulfidic/less sulfidic, high/low production, intense/weak chemical weathering conditions. The phosphogenesis of the nodules resulted in the phosphatization of small shelly fossils, which prevented the fossils from being dissolved during diagenesis, whereas the silica encrustation sealed the fossils within the nodules and thus protected the fossils from alteration by deep burial and surface weathering.

Plasma etching for carbon materials by inward RF plasma apparatus

ABSTRACT Diamond has high wear resistance and shape stability, and poly-crystalline chemical vapour deposition (CVD) diamond is difficult to mechanically process because of cleavage and wear anisotropy. On the other hand, diamond can be removed under an oxidising atmosphere with O2 as the etching gas by reactive ion etching which is processing using plasma. In this study, the fabrication of an inward radio frequency (RF) plasma apparatus and the possibility of a removal process for carbon materials such as CVD diamond film and graphite plate by using it were investigated. OES, confocal laser scanning microscope and Raman spectroscopy were used for the evaluation of the etching. It was confirmed that the inward RF plasma apparatus fabricated could be applied to plasma etching for carbon materials. In addition, it was suggested that carbon materials were etched as CO with O2 in the atmosphere, and amorphous structures were etched preferentially over crystalline ones.

Preliminary findings of confocal laser endomicroscopy and Raman spectroscopy in human breast tissue characterisation

Introduction: As highlighted within the ABS gap analysis, breast cancer re-excision rates for positive margin, estimated at 30% within conserving surgery, needs active research. Traditional intra-operative diagnostic techniques such as frozen section are timely, hence real time tools are necessary. We report on the diagnostic utility of probe confocal laser endomicroscopy (pCLE) and raman spectroscopy in the optical histopathological characterisation of frozen breast tissue.

Surface Modification of Porous Silica Particles with Carbohydrate Scaffolds as Receptor Components for Molecular Recognition.

Biosensors play a pivotal role in diagnosis through specific receptor-ligand interactions. However, receptor biomolecules such as proteins have inevitable stability issues due to denaturation. Alternatively, utilization of the small molecules multivalently presented on porous silica particles as receptor components is considered to address the stability issues. A series of receptor components was synthesized using carbohydrates as a chiral scaffold to support multiple functional groups. The synthesized molecules were attached on the porous silica particles. Raman spectral analyses of single silica particles in the presence of nitrobenzene derivatives revealed a specific interaction with 4-nitrophenol among others using a confocal Raman microscope. Chiral selective recognition was also accomplished for (1S,3S)- and (1R,3R)-2-amino-1-(4-nitrophenyl)-1,3-propanediols. Protected carbohydrate derivatives are shown to be useful as receptor components on porous silica particles.

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.

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.

Synthesis and Characterization of Anatase TiO2 Microspheres Self-Assembled by Ultrathin Nanosheets.

In this paper, we report a novel and simple method for synthesizing the microspheres self-assembled from ultrathin anatase TiO2 nanosheets with a high percentage of (001) facets via the hydrolysis process of the single-reagent (potassium fluorotitanate). We then used optical microscopy, scanning electron microscopy, and high-resolution confocal laser Raman spectroscopy to characterize the microspheres generated under different conditions. The study found that the size of the anatase TiO2 microspheres synthesized was 0.5–3 μm. As the synthesis time increased, the corroded surface of the microspheres gradually increased, resulting in the gradual disappearance of the edges and corners of the anatase nanosheets. The exposure percentage of the (001) facets of ultrathin anatase nanosheets synthesized for 2 h at 180–200 °C are close to 100%. The microsphere whose surface is completely covered by these anatase nanosheets also has nearly 100% exposed (001) facets. This new anatase nanosheet-based self-assembled microsphere will have great application potential in pollution prevention, environmental protection, and energy fields.

Formation of ZnO nanowires by anodization under hydrodynamic conditions for photoelectrochemical water splitting

The present work studies the influence of hydrodynamic conditions (from 0 to 5000 rpm) during Zn anodization process on the morphology, structure and photoelectrocatalytic behavior of ZnO nanostructures. For this purpose, analysis with Confocal Laser-Raman Spectroscopy, Field Emission Scanning Electron Microscope (FE-SEM) and photoelectrochemical water splitting tests were performed. This investigation reveals that hydrodynamic conditions during anodization promoted the formation of ordered ZnO nanowires along the surface that greatly enhance its stability and increases the photocurrent density response for water splitting in a 159% at the 5000 rpm electrode rotation speed.

A New Record of Acanthomorphic Acritarch Tappania Yin from the Early Mesoproterozoic Saraipali Formation, Singhora Group, Chhattisgarh Supergroup, India and its Biostratigraphic Significance

ABSTRACT In the present paper, well-preserved specimens of taxonomically distinctive Proterozoic eukaryotic fossil Tappania Yin are recorded for the first time from the rocks of the Saraipali Formation of the Singhora Group, Chhattisgarh Supergroup, India. In the global context, among the various species of this genus, Tappania plana is widely distributed in the latest Palaeoproterozoic (Statherian) to the early Mesoproterozoic (Calymmian) organic-walled microfossil assemblages. Tappania plana of the Saraipali is subjected to transmitted light microscopy, confocal laser scanning microscopy and laser Raman spectroscopy and these results are presented. Collectively, the occurrence of remarkable microfossil Tappania and other associated microfossils in the Saraipalli Formation of rocks demonstrate the Calymmian age for the lower sediments of the Chhattisgarh Supergroup.

Global microfossil changes through the Precambrian-Cambrian phosphogenic event: The Shabakta Formation of the phosphorite-bearing Maly Karatau Range, South Kazakhstan

Subtidal cherts from phosphorite-bearing basal strata of the Early Cambrian Shabakta (Dzhylandy) Formation, Tamda Group of the Maly Karatau Range of South Kazakhstan, contain a diverse assemblage of acanthomorph acritarchs and other well-preserved organic-walled microfossils. Acanthomorphs of the Shabakta lowermost layers are taxonomically essentially identical to those of many similarly aged Early Cambrian organic-walled compression-preserved and permineralized microbiotas preserved in rocks deposited in relatively open marine settings and are biostratigraphically correlative with acanthomorph-containing microfloral assemblages of the Vergale and Rausve Horizons (Regional Stages) of the East European Platform as well as with other assemblages known worldwide from the upper Atdabanian (Series 2 of the International Union of Geological Sciences [IUGS]). Although lower Atdabanian deposits of the Talsy (Lükati) horizon are missing from the Maly Karatau succession studied here, Nemakit-Daldynian through Tommotian (the IUGS Terranovian) microbiotas both of the Shabakta-underlying Berkuta Member of the Kyrshabakta Formation and phosphoritic Chulaktau Formation are comparable to those of the pre-trilobite Rovno and Lontova Horizons (Regional Stages) of the East European Platform. Thus, the phosphatized and chert-permineralized Shabakta assemblages date from of the Early Cambrian part of the Precambrian-Cambrian phosphogenic event, an interpretation supported also by associated small shelly fossils.The studies reported here of the Shabakta microfossils – based on the use of optical microscopy, confocal laser scanning microscopy (CLSM) and Raman spectroscopy – provide information in three dimensions at high spatial resolution about their organismal morphology, cellular anatomy, kerogenous composition, taphonomy, and mode and fidelity of preservation. The combined use of CLSM and Raman, techniques introduced to Precambrian paleobiology only rather recently, is shown to reveal morphological characters of taxonomic, biostratigraphic and palaeoenvironmental significance.

Effects of crystallographic orientation and negative rake angle on the brittle-ductile transition and subsurface deformation in machining of monocrystalline germanium

In this study, taper cutting experiments using a diamond tool were conducted to investigate the effects of negative rake angle and cutting orientation on the brittle-ductile transition and subsurface deformation of monocrystalline germanium cut on the (100), (101), and (111) planes. Confocal laser scanning microscopy and Raman spectroscopy were used to observe the three-dimensional surface topographies of the samples and characterize the subsurface deformation, respectively. The results showed that the negative rake angle and crystallographic orientation have a significant effect on the brittle-ductile transition and subsurface deformation mechanisms in ductile regime machining of monocrystalline germanium. A large negative rake angle alters the initial surface crack patterns, as well as anisotropic behavior of the ductile-brittle transition and subsurface deformation of monocrystalline germanium.

Effect of Scale Spallation During Coiling on the Electrochemical and Pickling Behavior of a Hot-Rolled Dual-Phase Steel

Tertiary oxide scale consists of magnetite and hematite, and in dual-phase steel strips were observed after the exit of final rolling stand in a thin slab casting rolling (TSCR) mill. Microscopic observation confirmed that these scales cracked and spalled off from many places of surface during coiling causing a non-uniform oxide layer on the steel surface. The present work discusses the synergistic effect of such non-uniform oxide layer and run-out-table cooling water on the electrochemical behavior of the dual-phase steel. The electrochemical response was assessed with the help of dynamic and linear polarization tests considering cooling water as electrolyte. The presence of non-uniform scale produced high cathodic (scaled zone) to anodic (spalled-off zone) area ratio that eventually led to extensive pitting corrosion in the present steel. Furthermore, the pickling behavior of the steel was also studied in detail. It was observed that the steel surface, with spalled-off area of about one-tenth of total surface area, corroded preferentially 3-4 times faster at spalled-off area than that of the uniformly pickled surface. The characterization study was performed using scanning electron microscopy, confocal laser 3D scanning microscopy, x-ray diffraction and Raman spectroscopy in order to establish the reasons for pitting corrosion due to the scale spallation.

High Correlation Between Structure Development and Chemical Variation During Biofilm Formation by Vibrio parahaemolyticus.

The complex three-dimensional structure of biofilms is supported by extracellular polymeric substances (EPSs) and additional insight on chemical variations in EPS and biofilm structure development will inform strategies for control of biofilms. Vibrio parahaemolyticus VPS36 biofilm development was studied using confocal laser scanning microscopy (CLSM) and Raman spectroscopy (RM). The structural parameters of the biofilm (biovolume, mean thickness, and porosity) were characterized by CLSM and the results showed that VPS36 biofilm formed dense structures after 48 h incubation. There were concurrent variations in carbohydrates and nucleic acids contents in the EPS as evidenced by RM. The Raman intensities of the chemical component in EPS, measured using Pearson’s correlation coefficient, were positively correlated with biovolume and mean thickness, and negatively correlated with porosity. The Raman intensity for carbohydrates correlated closely with mean thickness (p-value < 0.01) and the Raman intensity for nucleic acid correlated closely with porosity (p-value < 0.01). Additional evidence for these correlations were confirmed using scanning electron microscopic (SEM) and crystal violet staining.

Application of surface enhanced Raman scattering and competitive adaptive reweighted sampling on detecting furfural dissolved in transformer oil

Detecting the dissolving furfural in mineral oil is an essential technical method to evaluate the ageing condition of oil-paper insulation and the degradation of mechanical properties. Compared with the traditional detection method, Raman spectroscopy is obviously convenient and timesaving in operation. This study explored the method of applying surface enhanced Raman scattering (SERS) on quantitative analysis of the furfural dissolved in oil. Oil solution with different concentration of furfural were prepared and calibrated by high-performance liquid chromatography. Confocal laser Raman spectroscopy (CLRS) and SERS technology were employed to acquire Raman spectral data. Monte Carlo cross validation (MCCV) was used to eliminate the outliers in sample set, then competitive adaptive reweighted sampling (CARS) was developed to select an optimal combination of informative variables that most reflect the chemical properties of concern. Based on selected Raman spectral features, support vector machine (SVM) combined with particle swarm algorithm (PSO) was used to set up a furfural quantitative analysis model. Finally, the generalization ability and prediction precision of the established method were verified by the samples made in lab. In summary, a new spectral method is proposed to quickly detect furfural in oil, which lays a foundation for evaluating the ageing of oil-paper insulation in oil immersed electrical equipment.

Chips assembled cuboid-like nickel hydroxide/rGO composite material for high performance supercapacitors

In this paper, nickel hydroxide/rGO (Ni(OH)2/rGO) composite was successfully obtained in the existence of graphene oxide solution via hydrothermal method, with nickel nitrate hexahydrate as the nickel source, urea as the alkali source, and l-cysteine as the template. The structure and morphology of the composite were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), micro confocal laser raman spectroscopy (Raman) and BET surface analyzer. Finally, the electrochemical performance of the product was measured by electrochemical workstation. Morphological and structural analyses indicated that Ni(OH)2/rGO composite had good crystalline and a chips assembled cuboid structure with high specific surface area. Raman results indicated that the obtained composite has obvious D- and G-bands, which confirmed the Ni(OH)2/rGO composite was prepared successfully. Moreover, graphene was partially reduced during the hydrothermal reaction. Serving as the electrode material for supercapacitors, the Ni(OH)2/rGO composite exhibits high specific capacitance (1224 F/g at 2 A/g in the 3 M KOH), a nearly constant rate performance of 62.1% at current density ranging from 2 to 10 A/g, and 72.1% retention capacitance after 1000 continuous cycles. That indicates Ni(OH)2/rGO composite is promising electrode material for the electrochemical energy storage applications.