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Nano-sized SnO <sub/>2</sub> by a facile nanosecond laser irradiation in aqueous solution
摘要： A green and facile route was devised for the synthesis of SnO2 nanoparticles (NPs) using pulse laser irradiation of an aqueous solution of stannous chloride dihydrate and sodium hydroxide. The process employed ascorbic acid as a passivating agent, and SnO2 was obtained without any hazardous chemical reducing agent or high temperature calcination process. A nanosecond laser generating pulses with a peak wavelength of 355 nm and pulse repetition rate of 10 Hz was employed. Structural characterisations of the as-synthesized nanoparticles were carried out. The morphology of the SnO2 NPs were mostly spherical and their average crystalline sizes in the range 48.0–62.5 nm as obtained from the TEM images. The particles size showed a direct relationship with the irradiation time, and a decrease in the monodispersity was observed with increase in the time of exposure to the laser beam. The photocatalytic activity of the NPs, obtained with the least time of exposure to the laser beam, was evaluated for the photodegradation of methylene blue under visible light. The nanoparticles achieved about 84% efficiency towards the degradation of the dye within 180 min.
关键词： methylene blue,SnO2,laser irradiation,photocatalysis,nanoparticles
更新于2025-09-12 10:27:22
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Evaluation of laser-induced carbons with concentric graphitic layers for highly durable and adaptable at low humidity
摘要： Laser-induced carbons, so-called onion-like carbon (OLC), were investigated for enhanced oxygen reduction reaction activity, excellent durability of catalysts on carbon supports, and adaptability at a low relative humidity (44% RH). OLC nanoparticles were obtained by laser irradiation of ethylene with different reaction positions. The residence time and energy distribution at a reaction zone lead to the formation of nano-carbons with graphitic shells. As a robust support compared to commercial carbon black (XC), the OLC nanoparticle consisting of concentric graphitic layers is fabricated and its structure with sp hybridizations helps strong interactions between Pt atoms and π-bond of OLC nanoparticles, preventing the surface migration of Pt atoms, resulting in enhanced durability in long-term operations. It leads that the downshift of Pt d-band center at Pt nanocatalysts on OLC shells structures reduces the adsorption strength of surface oxygen species, enhancing ORR activity. Compared to the Pt/XC, the performance of Pt/OLC nanocatalyst shows 1.27 times more active in low humidity conditions, and 1.36 times more active and durable after long-term operating in extreme conditions occurring carbon corrosion levels. These results exhibit that the Pt/OLC catalyst is expected to generate an incredible level of synergy for enhanced activity and durability.
关键词： Durability,Graphitic layers,Laser irradiation,Onion-like carbons
更新于2025-09-12 10:27:22
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Influence of Pulsed He–Ne Laser Irradiation on the Red Blood Cell Interaction Studied by Optical Tweezers
摘要： Optical Tweezers (OT), as a revolutionary innovation in laser physics, has been extremely useful in studying cell interaction dynamics at a single-cell level. The reversible aggregation process of red blood cells (RBCs) has an important in?uence on blood rheological properties, but the underlying mechanism has not been fully understood. The regulating effects of low-level laser irradiation on blood rheological properties have been reported. However, the in?uence of pulsed laser irradiation, and the origin of laser irradiation effects on the interaction between RBCs remain unclear. In this study, RBC interaction was assessed in detail with OT. The effects of both continuous and pulsed low-level He–Ne laser irradiation on RBC aggregation was investigated within a short irradiation period (up to 300 s). The results indicate stronger intercellular interaction between RBCs in the enforced disaggregation process, and both the cell contact time and the initial contact area between two RBCs showed an impact on the measured disaggregation force. Meanwhile, the RBC aggregation force that was independent to measurement conditions decreased after a short time of pulsed He–Ne laser irradiation. These results provide new insights into the understanding of the RBC interaction mechanism and laser irradiation effects on blood properties.
关键词： red blood cells (RBCs),Helium–Neon laser,laser irradiation,optical tweezers,RBCs interactions
更新于2025-09-11 14:15:04
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Single-step formation of Cr 2 N nanoparticles by pulsed laser irradiation
摘要： Chromium nitride nanoparticles with mean diameter distribution between 0.8 nm and 30 nm were produced by laser irradiation of a chromium target immersed in liquid nitrogen. Cr was directly converted to chromium nitride nanoparticles according to selected-area electron diffraction analyses using the transmission electron microscopy technique. Crystalline nanoparticles mostly consist of Cr2N, which is commonly reported together with the conversion of Cr2N to CrN and the mixture of chromium oxides. In addition, there is no evidence of oxidation by storage or photodegradation of the nanoparticles in isopropyl alcohol suspensions. The intensity profile of small-angle X-ray scattering indicates that the geometrical shape of the nanoparticles is not spherical but cylindrical with aspect ratio (height-to-radius) of 0:35–0:05. UV-Vis absorption spectroscopy reveals the presence of surface plasmon absorption at the ultraviolet region at wavelengths of 350, 372, and 397 nm. First-principles calculations of density of states, dielectric function, and optical conductivity performed within the theoretical framework of density functional theory for Cr2N with a hexagonal structure corroborate the formation of surface plasmons.
关键词： transmission electron microscopy,liquid nitrogen,chromium nitride nanoparticles,density functional theory,laser irradiation,UV-Vis absorption spectroscopy
更新于2025-09-11 14:15:04
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An analytical solution of the bioheat model in a spherical tissue due to laser irradiation
摘要： This article studies an analytical approach associated with Laplace transform, experimental temperature data and a sequential concept over time to obtain the thermal damage and the temperature in living tissue due to laser irradiation. The effects of blood perfusion and the thermal relaxation time on the temperature of skin tissues and the resulting of thermal damage are investigated. The resulting of thermal damage to the tissue is assessed by the denatured protein range using the formulation of Arrhenius. The outcomes show that the hyperbolic bioheat model is reduced to the parabolic bioheat model when the relaxation time is close to zero. The numerical outcomes of thermal injuries and temperatures are graphically introduced. In conclusion, the comparison between the numerical computations and the existing experimental study displays that a current mathematical model is an effective tool for evaluating the biological heat transfer in biological tissues.
关键词： Laser irradiation,Laplace transforms,Thermal damages,Skin tissues
更新于2025-09-11 14:15:04
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Light-Tuned DC Conductance of Anatase TiO2 Nanotubular Arrays: Features of Long-Range Charge Transport
摘要： Experimental results related to the photoactivated dc conductance of anatase TiO2 nanotubular arrays (aTNTAs) under pulsed irradiation by a laser light inside and outside the fundamental absorption band are presented. It is found that the mobility and diffusion coefficients of charge carriers in the examined aTNTA are extremely low due to a strong charge-phonon coupling, abundance of shallow traps, and hopping conductivity between adjacent nanotubes. We consider that the confining electric field appeared within the array structure due to the difference in the local concentrations of excess electrons and holes at large values of the dc conductance suppresses the drift current. In this case, the dc conductance of such aTNTAs is mainly matured by the diffusion of mobile carriers. A recurrent kinetic model for evolution of the dc conductance of aTNTAs under laser irradiation has been proposed to interpret the experimental results.
关键词： anatase nanotubes,laser irradiation,dc conductance,Urbach energy,drift current,inter-band transition,diffusion current,charge mobility
更新于2025-09-10 09:29:36
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Photo and thermally induced properties change in Bi/Ag/Se trilayer thin film
摘要： In this article, we have demonstrated the optical and structural properties change in Bi/Ag/Se trilayer thin films by the influence of thermal and photon energy. The trilayer films prepared by thermal evaporation technique were annealed and laser irradiated at room temperature. The X-ray diffraction study revealed the Ag2Se phase formation and the surface morphology change is being studied by Field emission scanning electron microscopy. The optical properties of the studied films were characterized by using FTIR spectrophotometer in the wavelength range 400–1200 nm. The reduction of optical band gap by both thermal and laser irradiation is being discussed on the basis of chemical disorderness, defect states and density of localized states in the mobility gap. The Raman shift due to annealing and irradiation supports the changes in the film. The large change in optical band gap in thermal annealing is useful for memory device and waveguide fabrication.
关键词： optical properties,annealing,band gap,laser irradiation,Trilayer thin films
更新于2025-09-09 09:28:46