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oe1(光电查) - 科学论文

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?? 中文（中国） ▾

  • 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 CO 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

  • 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

  • Different hydrogen bonding environments of the retinal protonated Schiff base control the photoisomerization in channelrhodopsin-2

    摘要： The first event of the channelrhodopsin-2 (ChR2) photocycle, i.e. trans-to-cis photoisomerization, is studied by means of quantum mechanics/molecular mechanics, taking into account the flexible retinal environment in the ground state. By treating the chromophore at the ab initio multiconfigurational level of theory, we can rationalize the experimental findings based on pump–probe spectroscopy, explaining the different and more complex scenario found for ChR2 in comparison to other rhodopsins. In particular, we find that depending on the hydrogen bonding pattern, different excited states are involved, hence making it possible to suggest one pattern as the most productive. Moreover, after photoisomerization the structure of the first photocycle intermediate, P500, is characterized by simulating the infrared spectrum and compared to available experimental data. This was obtained by extensive molecular dynamics, where the chromophore is described by a semi-empirical method based on density functional theory. The results clearly identify which counterion is responsible for accepting the proton from the retinal Schiff base: the side chain of the glutamic acid E123.

    关键词： FTIR spectroscopy,quantum mechanics/molecular mechanics,retinal Schiff base,photoisomerization,channelrhodopsin-2,hydrogen bonding,excited states,molecular dynamics

    更新于2025-09-19 17:15:36

  • Biochemical Changes in Irradiated Oral Mucosa: A FTIR Spectroscopic Study

    摘要： Radiation exposure during the course of treatment in head and neck cancer (HNC) patients can induce both structural and biochemical anomalies. The present study is focused on utilizing infrared imaging for the identification of the minor biochemical alterations in the oral mucosa. Chemical maps generated using glycoprotein band indicates its differential distribution along the superficial layer. Spectra extracted from this layer suggests changes in overall nucleic acid and protein content in response to the therapeutic irradiation. Discrimination among control and irradiated groups have been achieved using principal component analysis. Findings of this preliminary study further support prospective utilization of Fourier Transform InfraRed (FTIR) imaging as a non-destructive, label-free tool for objective assessment of the oral mucosa in patient groups with or without radiation therapy.

    关键词： radiotherapy,head and neck cancer,FTIR spectroscopy

    更新于2025-09-19 17:15:36

  • Infrared-Spectroscopic Study of (4-Methylpent-3-en-1-ynyl)methylthiocarbene, Its Photochemical Transformations, and Reactions in an Argon Matrix

    摘要： The first representative of singlet carbenes bearing both ethynyl and methylthio groups at the carbene center, (4-methylpent-3-en-1-ynyl)methylthiocarbene, has been generated in a low-temperature Ar matrix upon UV photolysis of 3,3-dimethyl-5-methylthioethynyl-3H-pyrazole and detected by FTIR spectroscopy. The generation of the carbene proceeds via intermediate (3-diazo-5-methylhex-4-en-1-ynyl)methylsulfane. The comparison of FTIR spectroscopy data with the results of quantum chemical calculations (B3LYP/aug-cc-pVTZ) and NRT analysis shows that (4-methylpent-3-en-1-ynyl)methylthiocarbene has a singlet ground state with the localization of the unpaired spins on the carbon atom in the α-position to methylthio moiety. Two major pathways of further phototransformation of the studied carbene have been found. One of them produces photochemically stable thioketone (SCMe?CC?CHCMe2) as a result of methyl group migration from sulfur to the neighboring carbon atom, and the other one leads to the labile thioketene (SCC(Me)?CHCH?CMeCH2). Ability of (4-methylpent-3-en-1-ynyl)methylthiocarbene to insert into the H?Cl bond was established, which additionally confirms the singlet nature of this intermediate.

    关键词： H?Cl bond insertion,quantum chemical calculations,FTIR spectroscopy,thioketene,singlet carbenes,methylthio groups,ethynyl,phototransformation,thioketone

    更新于2025-09-19 17:13:59

  • [IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Breath Signatures of Cerebral Palsy Patients Revealed with Mid-Infrared FTIR Spectroscopy

    摘要： In the absence of “broadband” objective medical diagnostics, photonics technologies are now considered as a promising way to establish it. For example, being applied to human breath, under right conditions they should allow for unambiguous identification of metabolites circulating in blood and released in lungs alveoli as volatile organic compounds (VOCs). Nowadays, tremendous progress is achieved in developing laser-based mid-infrared spectrometers highly sensitive to VOCs [1,2]. Still, the spectral range covered by the laser spectrometers demonstrated so far, and signal-to-nose ratio (SNR) are not superior to conventional FTIR spectrometers based on thermal source. A significant amount of water vapour in breath is another, though general for all techniques, severe problem for VOCs detection. In addition to the detection, data analysis should be advanced in order to accurately compare healthy and diseased cohorts under study.

    关键词： cerebral palsy,FTIR spectroscopy,mid-infrared spectroscopy,breath analysis,VOCs

    更新于2025-09-16 10:30:52

  • Analysis of the degradation of encapsulant materials used in photovoltaic modules exposed to different climates in China

    摘要： This work investigates the degradation mechanisms of polymeric encapsulants used in photovoltaic modules. Two groups of photovoltaic modules, which were exposed to two typical climates, namely a hot-humid climate and a hot-dry climate, were investigated. Both types of modules were produced by Siemens Solar in 1992 and exposed to outdoor sunlight and the climate for 18 years. The results show that, depending on the climate conditions, the polymeric encapsulant materials exhibit different degradation mechanisms regarding the optical, chemical and morphological properties. The aging of polymeric encapsulant materials is, on the one hand, related to the working environment (moisture, sunlight intensity, UV content and temperature) and, on the other hand, also the conditions are not uniform across the modules: moisture ingress is more important at the edge of the module, oxygen diffusion is more important between cells than at the center of a cell, the module temperature is not uniform.

    关键词： Photovoltaic module,FTIR spectroscopy,Raman spectroscopy,EVA sample,Degradation behavior

    更新于2025-09-12 10:27:22

  • Ligand Binding-Induced Structural Changes in the M <sub/>2</sub> Muscarinic Acetylcholine Receptor Revealed by Vibrational Spectroscopy

    摘要： M2 muscarinic acetylcholine receptor (M2R) is a prototypical G protein-coupled receptor (GPCR) that responds to acetylcholine and mediates various cellular responses in the nervous system. Here, we used Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy analyses on M2R reconstituted in lipid membrane to understand the molecular mechanism behind the ligand binding-induced conformational changes. Upon agonist binding, M2R shows large spectral change of amide-I band corresponding to backbone C=O stretch, which likely connects with the receptor activation in lipid environment. These results pave the way to probe effects of different ligand binding on GPCRs using vibrational spectroscopy.

    关键词： ATR-FTIR spectroscopy,GPCR,M2R,Ligand,acetylcholine

    更新于2025-09-12 10:27:22

  • Structural characterization of Argania spinosa Moroccan wooden artifacts during natural degradation progress using infrared spectroscopy (ATR-FTIR) and X-Ray diffraction (XRD)

    摘要： The present work is focused on spectroscopic study of four samples of Argan wooden artifact pertaining to the 17th, 18th, 20th and 21st centuries. The objective is to characterize their unknown structures by the study of their non degraded parts and to investigate changes occurred in their degraded parts due to the natural degradation process. Attenuated total re?ectance Fourier transform infrared spectroscopy gauges the presence of many functional groups related to cellulose I and/or II (OH, C–O–C and –CH2), hemicelluloses (particularly C?O (cid:2)1), and lignin (OH phenolic, Car-O and C?Car) and provides qualitative information on the state of wood alteration by informing on the evolution of new former C?O bands. The degree of conversion to carbonyl group, especially quinone or p-quinone at 1650 cm (cid:2)1, is correlated to lignin degradation, while the absence of the C?O acetoxy absorption is ascribable to occurred deterioration in hemicelluloses, and (cid:2)1. X-ray diffraction determines the presence of two forms of cellulose; amorphous cellulose at 18.5(cid:3) 2θ and predominant crystalline cellulose Iβ at 2θ ? 22.6(cid:3) which characterized by an intense peak. The decrease of crystallinity index values con?rms the deterioration level and obvious changes in crystallinity level. However, the microcrystalline structure appears unaltered because no signi?cant changes were observed for calculated cristallite seize. The obtained results depend on the prolonged time of ageing, natural deterioration phenomena, and wood part (internal or external) that is exposed to degradation. The combination of these two methods is useful for an accurate estimation of the degradation level of argan wood.

    关键词： Chemistry,Argan wood artifact,XRD,Analytical chemistry,Natural product chemistry,Materials Chemistry,Natural degradation,Archaeology,ATR-FTIR spectroscopy,Crystallinity,Lignocelluloses,Structural characterization,Materials Science,Organic chemistry

    更新于2025-09-12 10:27:22

  • Developing infrared spectroscopic detection for stratifying brain tumour patients: glioblastoma multiforme <i>vs.</i> lymphoma

    摘要： Over a third of brain tumour patients visit their general practitioner more than five times prior to diagnosis in the UK, leading to 62% of patients being diagnosed as emergency presentations. Unfortunately, symptoms are non-specific to brain tumours, and the majority of these patients complain of headaches on multiple occasions before being referred to a neurologist. As there are currently no methods in place for the early detection of brain cancer, the affected patients’ average life expectancy is reduced by 20 years. These statistics indicate that the current pathway is ineffective, and there is a vast need for a rapid diagnostic test. Attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy is sensitive to the hallmarks of cancer, as it analyses the full range of macromolecular classes. The combination of serum spectroscopy and advanced data analysis has previously been shown to rapidly and objectively distinguish brain tumour severity. Recently, a novel high-throughput ATR accessory has been developed, which could be cost-effective to the National Health Service in the UK, and valuable for clinical translation. In this study, 765 blood serum samples have been collected from healthy controls and patients diagnosed with various types of brain cancer, contributing to one of the largest spectroscopic studies to date. Three robust machine learning techniques – random forest, partial least squares-discriminant analysis and support vector machine – have all provided promising results. The novel high-throughput technology has been validated by separating brain cancer and non-cancer with balanced accuracies of 90% which is comparable to the traditional fixed diamond crystal methodology. Furthermore, the differentiation of brain tumour type could be useful for neurologists, as some are difficult to distinguish through medical imaging alone. For example, the highly aggressive glioblastoma multiforme and primary cerebral lymphoma can appear similar on magnetic resonance imaging (MRI) scans, thus are often misdiagnosed. Here, we report the ability of infrared spectroscopy to distinguish between glioblastoma and lymphoma patients, at a sensitivity and specificity of 90.1% and 86.3%, respectively. A reliable serum diagnostic test could avoid the need for surgery and speed up time to definitive chemotherapy and radiotherapy.

    关键词： glioblastoma multiforme,brain tumour,infrared spectroscopic detection,lymphoma,machine learning,ATR-FTIR spectroscopy

    更新于2025-09-12 10:27:22