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Clear observation of the formation of nanoparticles inside the ablation bubble through a laser-induced flat transparent window by laser scattering
摘要： To understand the formation mechanism of nanoparticles via laser ablation in liquids direct observation of the dynamics inside the ablation bubble is essential. One powerful technique for this is small-angle X-ray scattering. Applying the laser-scattering technique in a similar context faces some difficulties, because, firstly the probe laser does not easily go into the bubble due to the curved bubble surface, and secondly the extremely weak scattering signal from inside the bubble is overwhelmed by the very strong reflection at the bubble surface. In this paper we solve those two problems by sending the probe laser into the bubble through a laser-induced flat transparent window, and demonstrate the clean observation of laser-scattering signals from the inside of the ablation bubble. We observe the signature of the formation of nanoparticles around the two areas inside the bubble, i.e., around the central area and apex inside the bubble. The scattering signals originating from the centre of the bubble persist throughout the entire growth and shrinkage stages of the bubble, while practically no scattering signals are found outside the bubble and this clearly implies that almost all nanoparticles are formed inside the bubble. Interestingly, the scattering signals originating from the apex inside the bubble gradually emerge after the bubble reaches the maximum size, and they become brighter as it further shrinks. Those findings are consistent with the scenario of nanoparticle formation obtained by small-angle X-ray scattering experiments.
关键词： nanomaterial synthesis,light scattering,nanoparticles,laser ablation,bubble dynamics
更新于2025-09-23 15:19:57
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Impact of refractive index increment on the determination of molecular weight of hyaluronic acid by muti-angle laser light-scattering technique
摘要： Hyaluronic acid (HA) is applied in a number of medical applications and HA of different molecular weight (Mw) are used in different pharmaceutical preparations. In determination of Mw by muti-angle laser light-scattering (MALS), refractive index increment (dn/dc) is an important parameter for accuracy. Herein, the influence of dn/dc on the Mw of HA in stroke-physiological saline solution is investigated by MALS in this work. Additionally, the Mw variation of HA in the manufacturing process of preparations is measured. It is shown that each HA sample corresponds to a specific value of dn/dc, which is varied from 1.38 to 1.74 L/g with the Mw increasing from 13.5 to 2840 kDa in solution. It is indicated by the results from both MALS approach and viscometry that appropriate dn/dc should be selected for Mw determination. In steam sterilization process of preparations at 121 °C, the Mw and conformation of HA can be accurately and rapidly determined by MALS. This work provides a precise method to determine the Mw of HA in the medical applications and preparation industries.
关键词： Molecular weight,Viscometry,Muti-angle laser light-scattering,Steam sterilization,Hyaluronic acid,Refractive index increment
更新于2025-09-23 15:19:57
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White Painting Pigment as a Low-Cost Light Scattering Material for Bilayer Photoelectrodes of Dye-Sensitized Solar Cells
摘要： White pigment (DuPont R902+) has been used as a light scattering material in the preparation of bilayer photoelectrodes of dye-sensitized solar cells (DSCs). The X-ray diffraction (XRD) pattern of the white pigment revealed that the material consists of rutile phase of titanium dioxide. The light scattering layer prepared from the white pigment was coated onto the main-layer of the photoelectrodes of DSCs. The solar cells with and without light scattering layer were tested in the simulated light of 100 mW/cm2. The DSCs with the light scattering layer generated more current density than the DSCs without scattering layer and the overall light to electric power conversion efficiency of DSCs with the light scattering layer was ~4.00 % compared with 3.25 % efficiency of the DSCs without the scattering layer.
关键词： Dye-sensitized solar cell,Photoelectrode,Light scattering layer,Transmittance,White pigment (R902+),Rutile titanium dioxide
更新于2025-09-23 15:19:57
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Visualizing Speech-Generated Oral Fluid Droplets with Laser Light Scattering
摘要： Aerosols and droplets generated during speech have been implicated in the person-to-person transmission of viruses, and there is current interest in understanding the mechanisms responsible for the spread of Covid-19 by these means. The act of speaking generates oral fluid droplets that vary widely in size, and these droplets can harbor infectious virus particles. Whereas large droplets fall quickly to the ground, small droplets can dehydrate and linger as “droplet nuclei” in the air, where they behave like an aerosol and thereby expand the spatial extent of emitted infectious particles. We report the results of a laser light-scattering experiment in which speech-generated droplets and their trajectories were visualized.
关键词： Covid-19,speech,virus transmission,laser light-scattering,droplets,aerosols
更新于2025-09-23 15:19:57
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Scanning atmospheric-pressure plasma jet treatment of nickel oxide with peak temperature of a??500 ?°C for fabricating pa??ia??n structure perovskite solar cells
摘要： Scanning atmospheric-pressure plasma jet (APPJ) treatment of nickel oxide with a peak temperature of 500 °C was performed for fabricating p–i–n structure perovskite solar cells (PSCs). APPJ post-treatment leading to enhanced light scattering in PSCs that in turn increases the haze of NiO on FTO glass, improves the cell efficiency. APPJ treatment on NiO also improves the wettability to facilitate the follow-up deposition of CH3NH3PbI3. This also leads to better PSC performance. X-ray photoelectron spectroscopy indicates that APPJ treatment results in fewer C–N bonds and reduced NiAc2 content, suggesting more complete conversion of the liquid precursor into NiO. With three APPJ scans, the average PCE improves from 11.91% to 13.47%, with the best-performing PSC achieving an efficiency of 15.67%.
关键词： X-ray photoelectron spectroscopy,light scattering,Scanning atmospheric-pressure plasma jet,perovskite solar cells,wettability,nickel oxide
更新于2025-09-23 15:19:57
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Localized Nanoscale Heating Leads to Ultrafast Hydrogel Volume-Phase Transition
摘要： The rate of the volume-phase transition for stimuli-responsive hydrogel particles ranging in size from millimeters to nanometers is limited by the rate of water transport, which is proportional to the surface area of the particle. Here, we hypothesized that the rate of volume-phase transition could be accelerated if the stimulus is geometrically controlled from the inside-out, thus facilitating outward water ejection. To test this concept, we applied transient absorption spectroscopy, laser temperature-jump spectroscopy and finite-element analysis modeling to characterize the dynamics of the volume-phase transition of hydrogel particles with a gold nanorod core. Our results demonstrate that nanoscale heating of the hydrogel particle core led to an ultrafast, 60 ns particle collapse, which is 2-3 orders of magnitude faster than the response generated from conventional heating. This is the fastest recorded response time of a hydrogel material, thus opening potential applications for such stimuli-responsive materials.
关键词： infrared spectroscopy,dynamic light scattering,nanorods,volume-phase transition,hydrogel,transient absorption
更新于2025-09-23 15:19:57
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Anomalous Light Scattering by Pure Seawater
摘要： The latest model for light scattering by pure seawater was used to investigate the anomalous behavior of pure water. The results showed that water exhibits a minimum scattering at 24.6 ?C, as compared to the previously reported values of minimum scattering at 22 ?C or maximum scattering at 15 ?C. The temperature corresponding to the minimum scattering also increases with the salinity, reaching 27.5 ?C for S = 40 psu.
关键词： light scattering by pure water,light scattering by pure seawater,light scattering,anomalous properties of water
更新于2025-09-19 17:15:36
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Rapid identification of wood species by near-infrared spatially resolved spectroscopy (NIR-SRS) based on hyperspectral imaging (HSI)
摘要： Conventional near-infrared (NIR) spectroscopy has shown its potential to separate wood species non-destructively based on the aggregate effect of light absorption and scattering values. However, wood has an aligned microstructure, and there is a large refractive index (RI) mismatch between the wood cell wall substance (n≈1.55) and the cell lumen (air≈1.0, water≈1.33). Light scattering is dominant over absorption μ′ (cid:31)( ) a in wood, and this fact can be utilized for complex classification purposes. In this study, an NIR hyperspectral imaging (HSI) camera combined with one focused halogen light source (? 1 mm) was designed to evaluate the light scattering patterns of five softwood (SW) and 10 hardwood (HW) species in the wavelength range from 1002 to 2130 nm. Several parameters were combined to improve the data quality, such as image histogram plots of defined spaced bins (associated with diffuse reflectance values of light), variance calculation on the frequency (the number of pixels in each bin) of each histogram and the principal component analysis (PCA) of all the variance values at each wavelength. The identification accuracy of the quadratic discriminant analysis (QDA) under the five-fold cross-validation method was 94.1%, based on the first three principal component (PC) scores.
关键词： spatially resolved spectroscopy,light scattering characteristics,wood species identification,hardwood,quadratic discriminant analysis (QDA),near-infrared hyperspectral imaging camera,principal component analysis (PCA),softwood,halogen spot-light source
更新于2025-09-19 17:15:36
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Optical properties of corals distort variable chlorophyll fluorescence measurements
摘要： Pulse amplitude modulated (PAM) fluorimetry is widely used in photobiological studies of corals, as it rapidly provides numerous photosynthetic parameters to assess coral ecophysiology. Coral optics studies have revealed the presence of light gradients in corals, which are strongly affected by light scattering in coral tissue and skeleton. We investigated whether coral optics affects variable chlorophyll fluorescence measurements and derived photosynthetic parameters by developing planar hydrogel slabs with immobilized microalgae and with bulk optical properties similar to those of different types of corals. Our results show that PAM-based measurements of photosynthetic parameters differed substantially between hydrogels with different degrees of light scattering but identical microalgal density, yielding deviations in apparent maximal electron transport rates by a factor of 2. Furthermore, system settings such as the measuring light intensity affected F0, Fm and Fv/Fm in hydrogels with identical light absorption but different degrees of light scattering. Likewise, differences in microalgal density affected variable chlorophyll fluorescence parameters, where higher algal densities led to greater Fv/Fm values and relative electron transport rates. These results have important implications for the use of variable chlorophyll fluorimetry in ecophysiological studies of coral stress and photosynthesis, as well as other optically dense systems such as plant tissue and biofilms.
关键词： light scattering,PAM fluorimetry,photosynthesis,hydrogels,variable chlorophyll fluorescence,coral optics
更新于2025-09-19 17:15:36
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Surface Plasmon Enhanced Light Scattering Biosensing: Size Dependence on the Gold Nanoparticle Tag
摘要： Surface plasmon enhanced light scattering (SP-LS) is a powerful new sensing SPR modality that yields excellent sensitivity in sandwich immunoassay using spherical gold nanoparticle (AuNP) tags. Towards further improving the performance of SP-LS, we systematically investigated the AuNP size effect. Simulation results indicated an AuNP size-dependent scattered power, and predicted the optimized AuNPs sizes (i.e., 100 and 130 nm) that afford extremely high signal enhancement in SP-LS. The maximum scattered power from a 130 nm AuNP is about 1700-fold higher than that obtained from a 17 nm AuNP. Experimentally, a bio-conjugation protocol was developed by coating the AuNPs with mixture of low and high molecular weight PEG molecules. Optimal IgG antibody bioconjugation conditions were identified using physicochemical characterization and a model dot-blot assay. Aggregation prevented the use of the larger AuNPs in SP-LS experiments. As predicted by simulation, AuNPs with diameters of 50 and 64 nm yielded significantly higher SP-LS signal enhancement in comparison to the smaller particles. Finally, we demonstrated the feasibility of a two-step SP-LS protocol based on a gold enhancement step, aimed at enlarging 36 nm AuNPs tags. This study provides a blue-print for the further development of SP-LS biosensing and its translation in the bioanalytical field.
关键词： signal amplification,surface plasmon resonance,gold nanoparticles,surface plasmon enhanced light scattering,gold enhancement
更新于2025-09-19 17:15:36