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Laser-Pulse Excitation of Coherent Vibrations of Dielectric Nanospheres in an Aqueous Suspension
摘要： Excitation of coherent vibrations of di?erent-sized polystyrene nanospheres at their acoustic eigenmodes in aqueous suspensions is observed in the laser pulse ?eld. To substantiate the observed features, a model of interaction of an electromagnetic ?eld with a dielectric in heterogenous media is developed which allows eigenmodes of nanospheres in a suspension to be calculated. The estimations are in satisfactory agreement with the experimental data.
关键词： Laser spectroscopy,acoustic eigenmodes,coherent vibrations,aqueous suspension,dielectric nanospheres,polystyrene nanospheres
更新于2025-09-16 10:30:52
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Phase-equilibrium measurement of a carbon dioxide/toluene/polystyrene ternary system using laser turbidimetry
摘要： The phase behavior of a carbon dioxide (CO2)/toluene (Tol)/polystyrene (PS) ternary system was measured. The measurements were performed using a synthetic method combined with a reflected light intensity measurement. The bubble points were determined by visual observation, and the cloud points were determined from the change in the reflected light intensity. The phase boundaries were measured at temperatures ranging from 313.2 K to 373.2 K and CO2 weight fractions ranging from 0.10 to 0.41. The homogeneous phase area decreased when the molecular weight of PS and/or the ratio of PS to Tol increased. It was found that the phase behavior of ternary systems, especially the liquid-liquid phase separation behavior, was altered by a change in the mutual solubility between the three components.
关键词： Toluene,Synthetic method,Carbon dioxide,Vapor-liquid equilibrium,Vapor-liquid-liquid equilibrium,Polystyrene,Laser turbidimetry,Liquid-liquid equilibrium
更新于2025-09-16 10:30:52
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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) - Accurate and Traceable Determination of Raman Shifts in Reference Material by Continuous-Wave Stimulated Raman Spectroscopy
摘要： Most Raman spectrometers require frequent calibration in order to provide accurate and repeatable results, and the calibration interval decreases for operation at high resolution. Wavenumber calibration commonly uses emission lines from gas-discharge lamps (e.g. mercury, neon, argon) that provide well-defined frequencies with very low uncertainties. However, it is often impractical to align lamps properly at the sample position, and the lamp emission lines provide absolute frequencies rather than Raman shifts. A more practical alternative is the use of a reference sample with a known Raman spectrum, which allows for the calibration of Raman spectrometer regardless of the excitation wavelength. Polystyrene is commonly used as a reference as it is easily available and practical to handle. We report on the application of continuous-wave stimulated Raman spectroscopy (CW-SRS) for accurate measurement of Raman shifts in polystyrene samples. Due to the narrow linewidth of CW radiation, CW-SRS achieves spectral resolution that is several orders of magnitude below those obtained with common Raman spectrometer or pulsed-based SRS. Furthermore, CW-SRS enables direct determination of the Raman shift by measuring the difference of pump and probe frequencies. For our application, we used an 852 nm diode laser as probe and a widely tunable external cavity diode laser as pump covering the wavelength range from 781 nm to 787 nm. Stimulated Raman gain was measured by modulating the pump amplitude at 10.4 MHz and detecting scattered light on the probe with a balanced photodetector and spectrum analyser. High frequency modulation and balanced detection ensured shot noise limited operation, which was confirmed by the scaling of the noise level and signal with probe power up to 4.5 mW (Fig. 1 (b)). Polystyrene spectra in the range 968 cm-1 to 1059 cm-1 were recorded by scanning the pump wavelength. Both pump and probe wavelengths were measured accurately by a wavelength meter traceable to a frequency standard. Values and uncertainties of the Raman shift of two Raman transitions in polystyrene were calculated according to the Guide to the Expression of Uncertainty in Measurement (GUM) [1]. The method was applied to two different polystyrene samples: a thin plate taken from a tool cabinet and a NIST traceable reference sample for FTIR. For the later, Raman shifts of 1001.15 ± 0.04 cm-1 and 1031.33 ± 0.21 cm-1 were measured. Compared with existing standards [2], we achieve up to one order of magnitude improvement on the uncertainty of the measured Raman shifts, thereby improving the metrology capability for characterization of reference material for Raman spectroscopy. Furthermore, shot noise operation paves the way towards the development of quantum-enhanced SRS with potential application in biological imaging.
关键词： Raman spectroscopy,continuous-wave stimulated Raman spectroscopy,metrology,polystyrene,calibration
更新于2025-09-12 10:27:22
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Intermingled Network of Syndiotactic Polystyrene/Poly(3-hexylthiophene)
摘要： By taking advantage of the fiber forming properties of both polymers in p-xylene, syndiotactic polystyrene (sPS) and poly(3-hexylthiophene) (P3HT) are mixed at an elevated temperature to prepare a composite network. These sPS?P3HT networks have been intensively investigated by UV?vis absorption, FTIR, and DSC; their morphologies by FE-SEM and FEG-TEM; and the molecular structure of the P3HT chains by neutron scattering experiments, rheology, and conductivity. Absorption measurements indicate the occurrence of π?π interaction between the P3HT chains and the sPS phenyl groups. Investigations by FESEM, TEM, and AFM show the formation of an intermingled network of sPS fibrils and P3HT ribbons. Small-angle neutron scattering studies reveal that a fraction of P3HT molecules is possibly encapsulated within the sPS fibrils. The increase of the elastic modulus with increasing P3HT content together with the increase of electrical conductivity is likely related to these encapsulated chains.
关键词： poly(3-hexylthiophene),composite network,syndiotactic polystyrene,π?π interaction,electrical conductivity
更新于2025-09-12 10:27:22
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Synthesis and characterization of SnO2 nanofiller from recycled expanded polystyrene
摘要： Polymer waste that has been viewed as a major threat to our environment is currently gaining attention as valuables resources are being obtained from it. Researchers are now developing nanocomposites/blends from plastic wastes as a way of recycling waste plastic rather than employing incineration and landfilling methods of recycling that are not environmentally friendly. The utilization of nanofiller to recycle waste polymers will enhance the mechanical, thermal and optical properties of the recycled polymers that are repeatedly degraded when they are managed via incineration and landfilling. The aim of this study is to prepare and characterize SnO2 nanofiller from recycled expanded polystyrene (rEPS) polymer wastes (PWs). A product was obtained, and it was characterized using BET, SEM and XRD. The BET showed microporous adsorption with surface area as 3.5880 m2/g, pore size 5.47314 m and the pore volume 0.004909 cm3/g, the SEM analysis showed spherical-shaped particles between 5 μm and 50 μm and the XRD indicated that the material is crystalline with tetragonal shape. This work showed a perfect way of upcycling waste polymers in a cost-effective manner and subsequently having the properties enhanced.
关键词： polymer wastes,SnO2,nanofillers,Environment,recycled expanded polystyrene
更新于2025-09-12 10:27:22
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Facile synthesis of novel gully-like double-sized mesoporous structural Sr-doped ZrO2–TiO2 composites with improved photocatalytic efficiency
摘要： Using polystyrene (PS) microspheres as an auxiliary template, a kind of novel gully-like Sr-doped ZrO2–TiO2 composites with the heterogeneous structure were successfully prepared by a simple instant centrifugation with one-step hydrolysis method. The Sr-doped ZrO2–TiO2 composites consisted of the tetragonal phase ZrO2, orthogonal phase SrZrO3 and anatase phase TiO2, showing a homogeneous concave and convex shape, similared to the naturally occurring gully terrain in nature, with a double-sized mesoporous structure. The SrZrO3 was prepared by the synthetic method in this study, which provided a new reference for the subsequent synthesis of SrZrO3. At the same time, Sr-doped ZrO2–TiO2 composites showed higher photocatalytic activity compared with the monomer and non-strontium-doped TiO2-ZrO2 under multi-mode photocatalytic conditions such as ultraviolet light, visible light, and simulated sunlight. The hydrogen production of Sr-doped ZrO2–TiO2 was 2.9 times and 4.4 times higher than that of TiO2–ZrO2 and TiO2, indicating that Sr-doped played a synergistic role in photocatalytic activity experiments. Finally, by the capturing experiment of gully-like Sr-doped ZrO2–TiO2, it was confirmed that h+,·OH, O2? were active species in the photodegradation of malachite green, and the possible mechanism of the photocatalytic reaction was deduced.
关键词： Sr-doped ZrO2–TiO2,Photocatalysis,Splitting water into hydrogen,Polystyrene microspheres
更新于2025-09-11 14:15:04
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[IEEE 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) - Greifswald, Germany (2018.9.23-2018.9.28)] 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) - Improved Surface Electrical Properties of Polystyrene in Vacuum by Plasma Modification
摘要： In order to satisfy the demand of improvement of industry insulation development, performance of polystyrene (PS) is urgent. It is believed that the accumulation of charge on the material can induce the distortion of local electric field, even cause surface flashover. Therefore, in this paper, in order to reduce the accumulation of surface charge, inorganic nano-films are deposited on the surface of PS by plasma modification technology. The plasma excitation source is AC high voltage generator with a frequency of 20 kHz. The PS samples are treated with tetraethoxysilane (TEOS) precursor assisted by plasma for 10 minutes. The working gas is argon and the pressure is sub-atmospheric (2 kPa). Before and after the plasma modification, charge accumulation and dissipation characteristics are measured. The results show that the decay rate of surface charge is increased obviously for modified PS. The Fourier Transform Infrared Spectrum (FTIR) indicates that new groups of Si-O-Si, Si-OH are formed on the sample surface. The trap energy level induced by the above groups is lower, namely, the shallow traps are beneficial to the dissipation of surface charge. Thus, the surface flashover withstand voltage is improved significantly.
关键词： plasma,surface modification,polystyrene,vacuum,surface flashover
更新于2025-09-10 09:29:36
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Fluorescence imaging of <i>Escherichia coli</i> on a rotating optical disk
摘要： We constructed a ?uorescence image from a rotating optical disk sample by aligning laser-scanned results based on positioning marks formed on the disk substrate. When Escherichia coli cells and 0.75-μm-diameter polystyrene beads were placed on the sample surface and a cell staining solution was used, ?uorescence from only E. coli cells was observed in the obtained image. This indicates that E. coli cells can be distinguished from polystyrene beads, an abiotic substance, in one image. A promising utilization of this method is as a sensor for ?nding targets among contaminants on a large area.
关键词： fluorescence imaging,Escherichia coli,sensor,polystyrene beads,optical disk
更新于2025-09-10 09:29:36
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A Novel In Situ Synthesis of Cu/Cu2O/CuO/Sulfonated Polystyrene Heterojunction Photocatalyst with Enhanced Photodegradation Activity
摘要： The heavy metal copper ion from the industrial wastewater were recycled by sulfonated polystyrene, which were converted to Cu/Cu2O/CuO/SPS heterojunction photocatalyst through the hydrothermal synthesis process. The hydrothermal synthesis temperature was investigated on the surface morphology, crystal structure and photocatalytic performance of the as-prepared samples. The samples were characterized by scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and UV–Vis diffuse reflectance spectra (UV–Vis DRS). The photocatalytic activities of the samples were investigated by the degradation of rhodamine B (RhB) under visible light irradiation. The results showed that Cu, Cu2O and CuO nanoparticles are uniformly distributed on the surface of sulfonated polystyrene microsphere. Meanwhile, the enhanced visible light absorption is originated from the surface plasmon resonance effect of Cu nanoparticles (CuNPs). The surface morphology and crystal structure of the sample were changed as the hydrothermal synthesis temperature rising. The sample by hydrothermal synthesis at 80 °C exhibited the preferable photocatalytic activity attributed the high dispersion of Cu, Cu2O and CuO nanoparticles and the formation of heterojunction between Cu2O and CuO.
关键词： CuO nanoparticles,Sulfonated polystyrene,Heterojunction,Cu2O nanoparticles,Cu nanoparticles,Photocatalysis
更新于2025-09-10 09:29:36
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Lectins at Interfaces—An Atomic Force Microscopy and Multi-Parameter-Surface Plasmon Resonance Study
摘要： Lectins are a diverse class of carbohydrate binding proteins with pivotal roles in cell communication and signaling in many (patho)physiologic processes in the human body, making them promising targets in drug development, for instance, in cancer or infectious diseases. Other applications of lectins employ their ability to recognize specific glycan epitopes in biosensors and glycan microarrays. While a lot of research has focused on lectin interaction with specific carbohydrates, the interaction potential of lectins with different types of surfaces has not been addressed extensively. Here, we screen the interaction of two specific plant lectins, Concanavalin A and Ulex Europaeus Agglutinin-I with different nanoscopic thin films. As a control, the same experiments were performed with Bovine Serum Albumin, a widely used marker for non-specific protein adsorption. In order to test the preferred type of interaction during adsorption, hydrophobic, hydrophilic and charged polymer films were explored, such as polystyrene, cellulose, N,-N,-N-trimethylchitosan chloride and gold, and characterized in terms of wettability, surface free energy, zeta potential and morphology. Atomic force microscopy images of surfaces after protein adsorption correlated very well with the observed mass of adsorbed protein. Surface plasmon resonance spectroscopy studies revealed low adsorbed amounts and slow kinetics for all of the investigated proteins for hydrophilic surfaces, making those resistant to non-specific interactions. As a consequence, they may serve as favorable supports for biosensors, since the use of blocking agents is not necessary.
关键词： lectin,gold,adsorption,bovine serum albumin,polystyrene,surface plasmon resonance spectroscopy,cellulose thin film
更新于2025-09-10 09:29:36