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Protective characterization of low dose sodium nitrite on yak meat myoglobin in a hydroxy radical oxidation environment: Fourier Transform Infrared spectroscopy and laser Micro-Raman spectroscopy
摘要： The effect of NaNO2 in hydroxyl radical-mediated oxidative damage of yak meat myoglobin was investigated. Laser micro-Raman spectroscopy and Fourier Transform Infrared spectroscopy were used to assess protein (carbonyls, total sulfhydryl and Disulfide bonds) oxidation, atomic (or molecular) interactions and secondary structural changes. The addition of NaNO2 during the oxidation of myoglobin significantly reduced the content of carbonyl and disulfide bonds and protected the sulfhydryl groups from hydroxyl radical oxidation (P < 0.05). There was no significant difference in the secondary structure of myoglobin between the control group and the SN treatment group(P > 0.05). At the same time, NaNO2 had an inhibitory effect on the expansion of the hemoglobin center size and the transition of Fe from a low spin state to a high spin state caused by radical-oxidized. These findings suggest that NaNO2 has potential for treatment effects in a hydroxyl radical-oxidized myoglobin.
关键词： Secondary structure,Hydroxyl radical,Raman spectroscopy,NaNO2,Myoglobin
更新于2025-09-11 14:15:04
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[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) - Dual-Colour-Pump Broadband CARS in Single-Ring Gas-Filled Photonic Crystal Fibre
摘要： Selective detection and chemical analysis of trace gases at concentration levels of parts per million (ppm) and below is of critical importance in environmental monitoring and medicine. Spectroscopic techniques offer high gas-type selectivity and are widely used for measuring the concentration of specific molecular species. Raman spectroscopy provides two key advantages. First, the pump wavelength can be freely chosen, independently of the absorption lines of the gas. Second, the highest Raman frequency shift of any gas is the vibrational transition of H2 at 125 THz, which means that all known Raman active molecules can be detected with one spectrometer. We report coherent anti-Stokes Raman spectroscopy (CARS) in single-ring hollow-core photonic crystal fibre (SR-PCF) using a dual-colour pump. The long collinear path-length offered by SR-PCF strongly enhances the efficiency of the Raman interactions, and furthermore the gas-filled SR-PCF has a zero dispersion wavelength which is pressure tuneable. By selecting an appropriate pressure, the dispersion can be arranged to be anomalous in the visible and at the same time normal in the ultraviolet. Under these circumstances, by fine-tuning the pressure to minimize dephasing, the Raman coherence prepared by seeded pumping in the visible can be used for phase-matched generation of an anti-Stokes signal from a second pump in the ultraviolet. This spectrally separates the 'preparation' pump from the 'read-out' pump. The low dephasing rate in the ultraviolet permits efficient generation, along the whole fibre length, of anti-Stokes signals from all known Raman-active gas molecules, which is a significant advantage compared to other spectroscopic techniques. The dual-colour pump scheme allows the main detection limit of CARS imposed by the non-resonant background (NRB) to be overcome. It exploits the fact that the NRB is a quasi-instantaneous effect, present only when pump and seed pulses overlap. Although this is also a requirement of Raman excitation, the resulting coherence wave has a lifetime of nanoseconds before it relaxes through intermolecular collisions. Therefore, by appropriately delaying the read-out pump pulse, it is possible to suppress the NRB. Figure 1(a) shows the CARS spectrum for two trace gases, H2 (500 ppm) and CH4 (600 ppm), mixed with the buffer gas N2, measured when the read-out pump overlaps with the Stokes seed. Figure 1 (b) shows the CARS spectrum for 20 ppm of H2 and 350 ppm of CH4, measured when the pump was delayed by 2 ns with respect to the Stokes seed. As can be seen from Fig.1, the dual-colour-pump CARS scheme in SR-PCF reduces the NRB by 120 dB, improving the detection limit by 15 dB and allowing detection of trace gas concentrations as low as 20 ppm with only 20 kW of peak pump power. This novel dual-colour-pump CARS approach has great potential in environmental monitoring and medical applications, offering high sensitivity, short acquisition times (several seconds) and simultaneous multi-species sensing.
关键词： Raman spectroscopy,photonic crystal fibre,dual-colour pump,CARS,trace gas detection
更新于2025-09-11 14:15:04
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Raman Spectroscopy Investigation of Polytetrafluoroethylene in Different Zones of Impact of Continuous CO2 Laser Radiation
摘要： The surface of polytetra?uoroethylene (PTFE) irradiated with an IR laser was investigated by Raman spectroscopy. The degree of change in the surface depends on the ?uence of the radiation and on the impact zones around the center spot of the laser beam. New absorption bands detected in the spectrum of the irradiated polymer indicate the formation of CF3 groups as a result of the destruction of the polymer chain. Polymer chain carbonization is also observed under laser irradiation. The process of structural changes in laser irradiated PTFE is re?ned on the basis of obtained microphotographs of the supramolecular structure. Density functional theory calculations are used to help in interpreting the Raman spectra.
关键词： Raman spectroscopy,CO2 laser ablation,supramolecular structure,polytetra?uoroethylene
更新于2025-09-11 14:15:04
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Unveiling coupled electronic and vibrational motions of chromophores in condensed phases
摘要： The quest for capturing molecular movies of functional systems has motivated scientists and engineers for decades. A fundamental understanding of electronic and nuclear motions, two principal components of the molecular Schr?dinger equation, has the potential to enable the de novo rational design for targeted functionalities of molecular machines. We discuss the development and application of a relatively new structural dynamics technique, femtosecond stimulated Raman spectroscopy with broadly tunable laser pulses from the UV to near-IR region, in tracking the coupled electronic and vibrational motions of organic chromophores in solution and protein environments. Such light-sensitive moieties hold broad interest and significance in gaining fundamental knowledge about the intramolecular and intermolecular Hamiltonian and developing effective strategies to control macroscopic properties. Inspired by recent experimental and theoretical advances, we focus on the in situ characterization and spectroscopy-guided tuning of photoacidity, excited state proton transfer pathways, emission color, and internal conversion via a conical intersection.
关键词： emission color,excited state proton transfer,electronic and vibrational motions,chromophores,photoacidity,femtosecond stimulated Raman spectroscopy,conical intersection,internal conversion
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE Photonics Conference (IPC) - San Antonio, TX, USA (2019.9.29-2019.10.3)] 2019 IEEE Photonics Conference (IPC) - Investigations on HI Reduced Graphene Based FET for Photon Detection
摘要： Reduced graphene oxide-based field effect transistor is fabricated and tested for detection of UV photons in 100-280 nm range. A novel technique is used for reduction of Graphene oxide. The fabricated device showed promising response to UV photons in terms of resistance change in rGO.
关键词： Reduced graphene oxide,UV photon detector,XRD,Field Effect Transistor,Raman spectroscopy
更新于2025-09-11 14:15:04
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Plasmon-Mediated Chemical Reactions on Nanostructures Unveiled by Surface-Enhanced Raman Spectroscopy
摘要： Surface plasmons (SPs) originating from the collective oscillation of conduction electrons in nanostructured metals (Au, Ag, Cu, etc.) can redistribute not only the electromagnetic fields but also the excited carriers (electrons and holes) and heat energy in time and space. Therefore, SPs can engage in a variety of processes, such as molecular spectroscopy and chemical reaction. Recently, plenty of demonstrations have made plasmon-mediated chemical reactions (PMCRs) a very active research field and make it as a promising approach to facilitate light-driven chemical reactions under mild conditions. Concurrently, making use of the same SPs, surface-enhanced Raman spectroscopy (SERS) with a high surface sensitivity and energy resolution becomes a powerful and commonly used technique for the in situ study of PMCRs.
关键词： Surface plasmons,Photothermal effects,Hot electrons,Hot holes,Surface-enhanced Raman spectroscopy,Plasmon-mediated chemical reactions
更新于2025-09-11 14:15:04
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Study of Charge Transfer at Quantum Dot-Graphene Interface by Raman Spectroscopy
摘要： Charge transfer at the interface is important for the optoelectronic and photochemical applications of quantum dot-two dimensional material (QD-2D) hybrids. In this work, Raman spectroscopy was exploited to characterize the CdS QD-graphene hybrids with varied thicknesses of graphene and QD layer. The selection of Raman excitation energies below the QD bandgap rules out the photoexcitation effects and thus we can focus on equilibrium charge transfer upon hybrid formation. Correlation analysis of Raman spectra shows evidences of electron transfer with concentration on the order of ~1012 cm-2, confirmed by electrical measurements. The method used in this study can be applied to characterize the interfacial interaction of various QD-2D hybrids.
关键词： hybrid interface,charge transfer,quantum dots,Raman spectroscopy,two-dimensional materials
更新于2025-09-11 14:15:04
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Electrotunable Nanoplasmonics for Amplified Surface Enhanced Raman Spectroscopy
摘要： Tuning the properties of optical metamaterials in real time is one of the grand challenges of photonics. Being able to do so will enable a class of adaptive photonic materials for use in applications such as surface enhanced Raman spectroscopy and reflectors/absorbers. One strategy to achieving this goal is based on the electrovariable self-assembly and disassembly of two-dimensional nanoparticle arrays at a metal liquid interface. As expected, the structure results in plasmonic coupling between NPs in the array but perhaps as importantly between the array and the metal surface. In such a system the density of the nanoparticle array can be controlled by the variation of electrode potential. Due to the additive effect, we show that less than 1 V variation of electrode potential can give rise to a dramatic simultaneous change in optical reflectivity from ~93 % to ~1 % and the amplification of the SERS signal by up to 5 orders of magnitude. The process allows for reversible tunability. These concepts are demonstrated in this manuscript, using a platform based on the voltage-controlled assembly of 40 nm Au-nanoparticle arrays at a TiN/Ag electrode in contact with an aqueous electrolyte. We show that all the physics underpinning the behaviour of this platform works precisely as suggested by the proposed theory, setting the electrochemical nanoplasmonics as a promising direction in photonics research.
关键词： plasmonics,surface enhanced Raman spectroscopy,electrotunable,nanoparticles,metasurface,self-assembly
更新于2025-09-11 14:15:04
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Microstructure and Spectroscopic Properties of AMoO4 (A = Ca, Ba) Particles Synthesized via Cyclic Microwave-Assisted Metathetic Route
摘要： AMoO4 (A=Ca, Ba) particles have been successfully synthesized via cyclic microwave-assisted metathetic route in ethylene glycol followed by further heat-treatment. The AMoO4 (A=Ca, Ba) particles were well crystallized after heat-treatment at 400-600 °C for 3 h. The microstructures exhibited fine morphologies with sizes of 0.5-1 and 1.5-2 μm for the CaMoO4 and BaMoO4 particles, respectively. The synthesized AMoO4 (A=Ca, Ba) particles were characterized by X-ray diffraction, scanning electron microscopy. Other spectroscopic properties were also examined using photoluminescence emission measurements and Raman spectroscopy.
关键词： Photoluminescence,Microwave-assisted metathetic route,AMoO4 (A=Ca, Ba),Raman spectroscopy,Microstructure
更新于2025-09-11 14:15:04
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Label-free Evaluation of Myocardial Infarct in Surgically Excised Ventricular Myocardium by Raman Spectroscopy
摘要： Understanding the viability of the ischemic myocardial tissue is a critical issue in determining the appropriate surgical procedure for patients with chronic heart failure after myocardial infarction (MI). Conventional MI evaluation methods are; however, preoperatively performed and/or give an indirect information of myocardial viability such as shape, color, and blood flow. In this study, we realize the evaluation of MI in patients undergoing cardiac surgery by Raman spectroscopy under label-free conditions, which is based on intrinsic molecular constituents related to myocardial viability. We identify key signatures of Raman spectra for the evaluation of myocardial viability by evaluating the infarct border zone myocardium that were excised from five patients under surgical ventricular restoration. We also obtain a prediction model to differentiate the infarcted myocardium from the non-infarcted myocardium by applying partial least squares regression-discriminant analysis (PLS-DA) to the Raman spectra. Our prediction model enables identification of the infarcted tissues and the non-infarcted tissues with sensitivities of 99.98% and 99.92%, respectively. Furthermore, the prediction model of the Raman images of the infarct border zone enabled us to visualize boundaries between these distinct regions. Our novel application of Raman spectroscopy to the human heart would be a useful means for the detection of myocardial viability during surgery.
关键词： label-free evaluation,myocardial viability,Raman spectroscopy,partial least squares regression-discriminant analysis,myocardial infarction
更新于2025-09-11 14:15:04