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Attenuated total reflectance spectroscopy to diagnose skin cancer and to distinguish different metastatic potential of melanoma cell
摘要： Early diagnosing of skin cancer and investigation of metastatic potential of cancer cells are very important to treat it appropriately. Infrared spectroscopy of biological tissues is an emerging technique which gives the spectral differences between healthy and diseased cells. In this work, we have demonstrated that attenuated total re?ectance Fourier transform (ATR-FTIR) spectroscopy can be used in diagnostic of skin cancer and in differentiating metastatic potential of cancer cells. Using IR spectroscopy, we can identify various types of cancer such as basal cell carcinoma, malignant melanoma, nevus and metastatic potential by alternations in hydration level and molecular changes. We examined biopsy of different types of cancer cells to diagnose skin cancer at early stages by using FTIR spectroscopy. To differentiate metastases we examined two human melanoma cells of same patient but at different metastatic potential and two murine melanoma cells with common genetic background but different metastatic potential. Our ?ndings revealed that melanoma changes the permeability of cell membrane and higher metastatic potential is related to the hydration level of cell membrane. Thus, ATR-FTIR spectroscopy is a potential technique to help in early diagnosing of skin cancer and to differentiate different metastatic potentials.
关键词： ATR-FTIR,Metastatic,spectroscopy,melanoma
更新于2025-09-23 15:21:01
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Fabrication of frequency selective metamaterial structure using low-cost laser writer
摘要： Tailoring the metamaterial structure using Laser writer lithography system offers a feasible way to accomplish the fine cross grating structures. The main focus of this work is to fabricate a metamaterial for absorption in the far infrared (far-IR) spectrum. Fabrication was carried out using homemade laser writer working at 405 nm in S1813 photoresist coated upon chromium on glass followed by its etching in the exposed regions. A 40 ? 40 array of unit cells with dimension in the order of 28 μm ? 1 μm were achieved. The structural characterization was carried out using scanning electron microscope (SEM) and Optical Microscope. We could observe clear absorption in the far-IR region. The results here would be favorable for the development of devices based on artificial material whose properties are not readily accessible in nature (metamaterials).
关键词： Optical microscope,FTIR,Laser writer,Metamaterial,SEM
更新于2025-09-23 15:19:57
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Laser-Induced Voltage of Oil Shale during Retorting
摘要： In this study, a 248 nm laser was used to analyze oil shale at di?erent pyrolysis temperatures. An induced voltage was obtained when the ultraviolet laser irradiated the oil shale surface. The laser-induced voltage (LIV) peak decreases with temperatures below 200 °C, increases with temperatures in the range 200?400 °C, and then decreases above 400 °C. The critical temperatures of 200 and 400 °C corresponded well with the points conformed using thermogravimetry and di?erential scanning calorimetry (TGA-DSC), gas chromatography and gas chromatography coupled (TG-FTIR-MS), and scanning electron microscopy (SEM). Our research suggested that an LIV method could be applied to the analysis of the oil shale pyrolysis process.
关键词： oil shale,TGA-DSC,TG-FTIR-MS,pyrolysis,laser-induced voltage,SEM
更新于2025-09-23 15:19:57
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Dynamic Diffusion of Disperse Dye in a Polyethylene Terephthalate Film from an Infrared Spectroscopic Perspective
摘要： The di?usion behavior of a typical disperse dye, disperse red 9 (DR 9), in the polyethylene terephthalate (PET) ?lm at di?erent temperatures was investigated by attenuated total re?ection?Fourier transform infrared spectroscopy and 2D correlation spectroscopy (2Dcos) analyses. According to the Fickian di?usion model, the calculated di?usion coe?cients of DR 9 in the PET ?lm at di?erent temperatures were observed to increase with temperature, which might be attributed to the increased free volume and thermal motion in the PET matrix and the rapid movement of DR 9 molecules at higher temperatures. In-detail analysis of the di?usion spectra discerned various kinds of molecular interactions, including intramolecular hydrogen bonding interactions of DR 9 and dipole?dipole and π?π interactions between DR 9 and PET. Among these, the dipole?dipole interactions between CO groups of DR 9 and PET occurred ?rst and played a vital role during the di?usion process of DR 9, as deduced from the sequence order of group motions in 2Dcos analysis.
关键词： ATR-FTIR spectroscopy,2D correlation spectroscopy,polyethylene terephthalate,diffusion,disperse dye
更新于2025-09-23 15:19:57
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Infrared spectroscopic analysis on structural changes around the protonated Schiff base upon retinal isomerization in light-driven sodium pump KR2
摘要： Krokinobacter rhodopsin 2 (KR2) was discovered as the first light-driven sodium pumping rhodopsin (NaR) in 2013, which contains unique amino acid residues on C-helix (N112, D116, and Q123), referred to as an NDQ motif. Based on the recent X-ray crystal structures of KR2, the sodium transport pathway has been investigated by various methods. However, due to complicated structural information around the protonated Schiff base (PRSB) region in the dark state and lack of structural information in the intermediates with sodium bound in KR2, detailed sodium pump mechanism is still unclear. Here we applied comprehensive low-temperature light-induced difference FTIR spectroscopy on isotopically labeled KR2 WT and site-directed mutant proteins (N112A, D116E, R109A, and R109K). We assigned the N-D stretching vibration of the PRSB at 2095 cm?1 and elucidate the hydrogen bonding interaction with D116 (a counter ion for the PRSB). We also assigned strongly hydrogen-bonded water (2333 cm?1) near R109 and D251, and found that presence of a positive charge at the position of R109 is prerequisite for the pumping function of KR2.
关键词： Retinal,Sodium ion pump,Low-temperature FTIR,Protein-bound water,Hydrogen bond
更新于2025-09-23 15:19:57
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Spectroscopic Characterization of Emulsions Generated with a New Laser-Assisted Device
摘要： This paper presents a spectroscopic study of emulsions generated with a laser-assisted device. Fourier transform infrared (FTIR), Raman and UV–Vis–NIR reflectance spectra of emulsions, recorded before and after exposure to laser radiation were used to characterize the effect of laser irradiation. The paper also presents a comparison between the calculated IR spectra and the experimental FTIR spectra of an emulsion’s components. FTIR measurements allowed the identification of absorption bands specific to each of the emulsions’ components. Moreover, it enabled the observation of destabilization of the emulsion in real-time. Raman spectroscopy allowed the observation of the modifications at a molecular level, by identifying the vibrations of the representative functional groups and the polymerization of sodium tetradecyl sulfate (STS) molecules by analyzing the evolution of the carbonyl band. UV–Vis–NIR reflectance spectra of emulsions before and after exposure to laser radiation showed that the physical characteristics of the emulsions changed during irradiation—the dimensions of the droplets decreased, leading to an emulsion with a better time stability. These results proved that the employed spectroscopy techniques were powerful tools in emulsion analysis.
关键词： UV–Vis–NIR reflectance spectroscopy,FTIR spectroscopy,emulsion,Raman spectroscopy
更新于2025-09-23 15:19:57
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Spectroscopic studies of silica-incorporated lanthanum ?2-diketonate complexes for application in optoelectronic devices
摘要： In the present research work, silica-incorporated complexes of lanthanum β-diketonate were synthesized. Structural characterization of the prepared complexes was made on the basis of FTIR and FESEM studies. Shifting of peaks in the FTIR spectra are discussed in relation with the complexation, also incorporation of silica in complexes was confirmed by the FTIR spectra. FESEM and EDX studies were performed to know the surface morphology as well as elemental composition of the prepared complexes. The optical properties such as diffuse reflectance and photoluminescence were studied to get the idea about the possible transitions among the energy levels of the complexes as well as to know the emission peaks. The assignment of luminescence band is determined from excited state lifetime. The variation in luminescence intensity with time was measured by recording decay curves at fixed emission wavelength. The life time for all the three complexes was measured in micro-second (μs) order. Color coordinates of the complexes lie in the blue region. Thermal stability of the complexes was checked by measuring the loss in weight as a function of temperature.
关键词： FESEM,silica-incorporated lanthanum β-diketonate,FTIR,thermal stability,photoluminescence
更新于2025-09-23 15:19:57
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Effect of thioglycolic acid molecules on luminescence properties of $$\hbox {Ag}_2$$Ag2S quantum dots
摘要： For monoclinic Ag2S nanocrystals (quantum dots, Ag2S/TGA QDs), the correlation between their luminescence properties and aspects of their passivation by thioglycolic acid (TGA) molecules is considered. The features of quantum confinement effect in the QDs absorption and photoluminescence spectra are analyzed for Ag2S QDs with an average size of 1.7–3.1 nm. We show that, in various conditions of passivation of QDs interfaces, the luminescence mechanism of Ag2S/TGA QDs is switched from recombination luminescence in the 870–1000 nm region to exciton luminescence with a band maximum at 620 nm. By means of FTIR spectra, two major types of interactions between TGA molecules and Ag2S QDs, arising due to changing the [Ag+]:[S2?] ratio from 1:0.9 to 1:1.43, are determined. Exciton luminescence (620 nm) occurs in case of using TGA as the sulfur source in Ag2S crystallization and the interface passivation agent, with [Ag+]:[S2?] = 1:1. The analysis of the FTIR spectra indicates bonding of TGA with the Ag2S surface by both thiol and carboxylic groups in this case. With increasing the sulfur concentration in the synthesis of Ag2S/TGA QDs, the exciton luminescence is suppressed. The employment of Na2S as the sulfur source in Ag2S crystallization with TGA acting as the surface passivation agent promotes the formation of recombination centers for IR luminescence. In this case, analysis of the FTIR spectra indicates passivation of Ag2S QDs by TGA molecules due to adsorption of thiol groups. It is found that the photodegradation or IR luminescence of Ag2S/TGA QDs upon exposure to exciting radiation is due to the photolysis of Ag2S nanocrystals with formation of luminescence quenching centers as well as due to photodestruction of TGA molecules.
关键词： Size dependence,Thioglycolic acid,Interaction mechanism,FTIR spectra,Trap state luminescence,Silver sulfide,Luminescence properties
更新于2025-09-23 15:19:57
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Thioglycolic Acid FTIR Spectra on Ag2S Quantum Dots Interfaces
摘要： The mechanism features of colloidal quantum dots (QDs) passivation with thioglycolic acid molecules (TGA) for cases of different luminescent properties is considered using FTIR. This problem is considered based on FTIR spectra analysis for various ionic forms of TGA. Experimental TGA molecules FTIR spectra is interpreted, basing on the data on modeling of TGA vibrational modes, realized in the framework of density functional method (DFT /B3LYP/6-31+G(d)) taking into account the vibrations anharmonicity of every functional group. This approach provides a significant improvement in the agreement between the experimental and calculated data. FTIR spectra of Ag2S/TGA QDs with exciton and recombination luminescence are differ from each other and B “freeB” TGA molecules. The ν(S ? H) TGA peak (2559 cm?1) disappears in FTIR spectra of Ag2S/TGA QD samples. This fact indicates the interactions between TGA thiol group and dangling bonds of Ag2S nanocrystals. Ag2S QDs passivation with TGA molecules leads to emergence νas(COO?) (1584 cm?1) and νs(COO?) (1387 cm?1) peaks. It indicates TGA adsorption in ionic form. For Ag2S/TGA QDs with exciton luminescence we observed (a) significant low-frequency shift of νs(COO?) peak from 1388 cm?1 to 1359 cm?1 and high-frequency shift of νas(COO?) peak from 1567 cm?1 to 1581 cm?1; (b) change in the ratio of intensities of νas(COO?) and νs(COO?) vibrations. This feature is caused by the change in the symmetry of TGA molecules due to passivation of Ag2S quantum dots.For Ag2S/TGA QDs with recombination luminescence, the insignificant high-frequency shift of 7–10 cm?1 for νas (COO?) at 1567 cm?1 and low-frequency shift of 3–5 cm?1 for νs (COO?) at 1388 cm?1, probably caused by the interaction of thiol with Ag2S surface is observed. Using FTIR spectra, it was found that IR luminescence photodegradation is also accompanied by changes in the thioglycolic acid molecules, which capped Ag2S QDs. In the case of Ag2S QDs with exciton luminescence, the degradation process is non-reversible. It is accompanied by TGA photodegradation with the formation of α-thiol-substituted acyl radical (S-CH2-CO?) TGA.
关键词： photodegradation,FTIR spectra,thioglycolic acid (TGA),dimer,luminescence,Ag2S quantum dots,ionic form
更新于2025-09-23 15:19:57
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Spectroscopic and Electrical Properties of Ag2S/PVA Nanocomposite Films for Visible-Light Optoelectronic Devices
摘要： Polymer nanocomposites are potential materials in the industrial sector and in our daily life due to their diverse properties and applications. Throughout the present study, solution casting technique has been used to prepare polyvinyl alcohol (PVA) filled with different weight (wt.) ratios percentages (%) (0, 0.01, 0.1, 1.0 and 10.0 wt%) of silver sulfide nanoparticles (Ag2S NPs). The concentration dependence of spectroscopic and electrical behaviors based on PVA polymer dispersed with Ag2S has been investigated. The prepared films with the variation of loading filler concentrations from 0 to 10 wt% have been characterized by different spectroscopic techniques. Fourier transform infrared (FTIR) analysis confirmed the successful incorporation of Ag2S nanoparticles in the PVA matrix by studying the changes of the characterizing bands which reveal the interaction within the composite structure. Whilst photoluminescence (PL) spectra of the Ag2S/PVA nanocomposite films showed an interesting peak covering the entire range of interest for visible light optoelectronic devices at a very low concentration of the loading filler of Ag2S. The electrical properties of the plain and Ag2S NPs doped PVA nanocomposites have been studied using DC electrical conductivity (σDC) measurements performed over a temperature (T) range from 298 to 373 K. The study demonstrates the increase of the DC electrical conductivity with increasing filler content of Ag2S by three orders of magnitude. DC conductivity also showed temperature dependent behavior where the conductivity enhanced by five orders of magnitude when temperature increased up to 373 K. These novel results present Ag2S/PVA nanocomposites as a promising material in optoelectronics applications.
关键词： DC conductivity,FTIR spectroscopy,Ag2S,PVA nanocomposites,Photoluminescence,Optoelectronic devices
更新于2025-09-23 15:19:57