Increasing Irradiation Time Research Articles

Effect of Laser Irradiation with 532 nm Wavelength on The Optical Properties of PVA/MR Solutions

Background: This work aims to study the impact of 532 nm laser irradiating on the optical properties of the Polyvinyl alcohol/ Methyl Red (PVA/MR) solution before and after laser irradiation 32mW with various times (0, 20, 30 and 40) minutes. Materials and Methods: The polymer (PVA) powder 500 mg was dissolved in 50 ml distilled water at temperature 80 ˚C and the methyl red (MR) 30 mg was dissolved in 10 ml at temperature 80 ˚C using solution dilution formula . A semiconductor laser with a wavelength of 532 nanometers was used to irradiate the solution. Results: The absorbance, reflectance, and transmittance spectrum of solution prior to and following laser irradiation were recorded. Then, the optical constants and energy gap were calculated. Conclusions: The irradiation with the 532nm laser leads to a break of the bonds (From the absorbance spectrum, it decreases as the irradiation time increases. This indicates the breaking of bonds.) that results in an increase in the transmittance spectrum, and the energy gap.

Au/ZnO nanocomposites based on simple laser ablation method for water treatment

A binary heterostructure of Au/ZnO nanocomposite is prepared in a novel way based on successive pulsed laser ablation of the two targets in an aqueous solution with varied pulse time. The development of the method allows generating a noble metal (Au) and metal oxide (ZnO) one after one to produce a novel heterostructure with a tunable shell applicable as a catalytic degradable material. The nanocomposite samples are tested to study their optical, morphological, and structural properties. The photocatalytic degradation study demonstrates a significant decrease in the absorbance intensity of Rohdamin B (RhB) dye as the irradiation time increases. It indicates a reduction in dye concentration with a remarkable improvement in contact time. Besides, the degradation percentage against pH value is investigated. It reveals an increasing trend as the pH value rises with a maximum percentage at pH 10. The study is also concerned with the influence of the initial concentration of RhB dye on the degradation efficiency of the nanocomposite. Higher initial concentrations of the dye lead to a decrease in the degradation efficiency of the catalysts. Finally, the kinetic analysis of RhB photodegradation reveals that the Langmuir-Hinshelwood first-order kinetic model accurately describes RhB's adsorption onto the nanocomposites.

Extraction evolutionary features of continuous light-induced plasmonic nanobubbles by a dynamic spectral regression model

A comprehensive understanding of the nature of light-induced plasmonic nanobubbles (PNBs) generated around noble metal nanoparticles is essential for optimizing PNB-based applications, such as light-driven microfluidic control. To investigate the overall evolution pattern of plasmonic nanobubbles (PNBs) under continuous light illumination, a computational model based on the least-squares method is established. Meanwhile, the variations in nanofluid transmittance and vaporization mass under continuous light illumination are measured by an immersion fiber and an electronic balance, respectively. The effects of nanoparticle concentration on the nanofluid transmittance and vaporization mass are analyzed. Considering the variations in nanofluid concentration, the overall evolution pattern of PNBs is preliminarily analyzed by monitoring the real-time dynamic change in nanofluid transmittance. The experimental results indicate that the nanoparticle concentration has an important effect on the nanofluid vaporization process. During the illumination stage, an increased nanofluid concentration intensifies the synergistic effect of water vaporization and PNB growth on transmittance reduction. The change in nanofluid transmittance caused by PNB scattering greatly exceeds that caused by increasing nanoparticle concentration. The nanofluid concentration gradually increases and peaks at the end of the cooling stage, and the rate of change of the nanofluid concentration is proportional to the nanofluid concentration. The numerical calculations show that the average size and the range of the PNB size distribution continuously increase with increasing irradiation time, and decrease during the cooling stage. A higher nanofluid concentration corresponds to a wider range of PNB size distribution.

Optimizing photocatalytic performance with Ag-doped ZnO nanoparticles: Synthesis and characterization

The development of nanotechnology has significantly impacted the improvement of photocatalytic performance of ZnO NPs. In this study synthesis of pure ZnO and Ag–ZnO nanoparticles via a co-precipitation method at varying Ag concentrations (1 %, 2 %, 3 %, 4 % and 6 %) to enhance their photo catalytic efficacy. X-ray diffraction (XRD) analysis estimates crystallite size which decreased by increasing Ag concentration, ranging from 30.6 nm (Pure ZnO) to 22.5 nm 6 % Ag-doped ZnO. Scanning electron microscopy (SEM) revealed decrease in particle size with increasing Ag content. UV–Vis spectroscopy indicating a narrowed band gap of optimal sample. Photocatalytic activity of the synthesized nanoparticles was evaluated using methylene orange (MO) dye degradation under light irradiation. The MO concentration exhibited a decrease with increasing irradiation time in the presence of photocatalysts. Recombination rate of NPs decreases by increasing the concentration of Ag i.e. 4%Ag dope ZnO NPs have lowest recombination rate and maximum degradation efficiency. FTIR analysis confirms the preparation of Ag-doped ZnO NPs. This improvement can be credited to the synergistic effect of Ag doping, leading to a narrowed band gap and potentially maximum degradation of MO by using Ag-doped ZnO NPs.

A robust, durable and eco-friendly UV-cured wood film with self-matting and anti-fingerprint performance via wrinkled structure

With the changes in people's living standards and aesthetic perspectives, the matting films with wrinkled surfaces play a crucial role in fields such as decorative materials, wooden furniture, wood-based panels and industrial coatings. In this paper, the UV-cured polyurethane acrylate (PUA) films with self-matting and anti-fingerprint performance on the wood-based panels was prepared and developed the wrinkled surface by using excimer/mercury dual UV curing. The results showed that the roughness, wavelengths (λ) and amplitudes (A) of wrinkles surface were positively correlated with the excimer irradiation time and negatively correlated with the mercury lamp irradiation time. Furthermore, the increasing irradiation time improved the degree of curing and crosslink density of the cured films, which enhanced the mechanical properties and durability of the cured film. Consequently, the prepared UV-cured PUA film exhibited excellent self-matting with a gloss of 3.4 GU at an incident angle of 60° and maintained the gloss value < 5 GU after 500 times rubs and 1 hour corrosion. Additionally, the self-matting films with wrinkled surface enhanced the hydrophobicity and anti-fingerprint performance of the surface. Besides, the cured film presented high physical performance with hardness of 4 H and adhesion of 0 grade. These results provide a reference for the further application of self-matting films in wood-based panels, furniture and interior decoration fields.

A Static Laser Weeding Device and System Based on Fiber Laser: Development, Experimentation, and Evaluation

To demonstrate the feasibility and improve the implementation of laser weeding, a static movable lift-adjustable closed fiber laser weeding device and system have been developed, followed by experiments and performance evaluations. Physical experiments were conducted on the energy required for laser cutting of weed stems, targeting four common larger weeds (Chenopodium album, Amaranthus spinosus, Setaria viridis, and Eleusine indica) in farmland and orchards. At the same irradiation distances, the energy required to cut the same type of large weed generally increases with increasing distances and stem diameters but decreases with increasing irradiation time. The variance of stems’ power density after irradiation was larger and the values were more dispersed for Chenopodium album and Setaria viridis weeds, and the values were relatively scattered, while the power density values of Amaranthus spinosus and Eleusine indica weeds were more concentrated. When the irradiation time was 10 s, the 3.892 W/mm2 laser was sufficient to eliminate weeds and plants with the irradiation distances of 2 m. The 2.47 W/mm2 laser was more effective, as it killed weeds within a distance of 1 m in less than 1 s. This work demonstrates the feasibility of the laser weeding device and system that can completely cut off the stems of large weeds, and this technology has the potential to promote sustainable agriculture.

Enhancement of photothermal effect of Cu2S@CuS homojunction and applications of crude oil–water separation and ice removal

The recycle of crude oil with high viscosity from wastewater and anti-icing of outdoor power transmission lines are still challenges. High photothermal responses with excellent superwetting properties are critical issues for solving these problems. In the paper, the porous nanosheet arrays of Cu2S@CuS homojunction with narrow band have been prepared by anodizing Cu foam. After the surface modification of stearic acid (STA), the array surface is endowed with excellent wetting states of super-hydrophobicity and super-lipophilicity, and is suitable for the oil–water separation. The narrow band and homojunction structure induce the excellent light absorption, and further increase the photothermal conversion efficiency of the prepared Cu2S@CuS nanoarray to the value of 8.81 %. Under the irradiation of Xe lamp with 0.1 W/cm2, the surface temperature of Cu2S@CuS nanosheet array in air promptly increases to 96.5 ℃ from room temperature of 20.9 ℃ within 30 s, and increases to 69 ℃ from room temperature within 45 s in crude oil. Obviously, the prepared Cu2S@CuS nanoarrays with excellent photothermal responses are very suitable to be used as filter film for the crude oil–water separation. With the increase of light irradiation time, the local temperature of crude oil near the filter film continues to be increased to 69 ℃ within 45 s, and the gradually warmed crude oil was continuously pumped to the oil collecting beaker through rubber pipe, showing the high efficiency and excellent stability. Of course, it is also used to efficiently separate the oil with low viscosity from oil-water mixtures and emulsion.

Probing the structure of divalent impurity cations doped ceria nanocubes for photocatalytic activity

Ceria has attracted a lot of interest in scientific community due to its several technological uses. During this study, composite hydroxide-mediated method was used to prepare nanocubes of undoped and doped ceria. The prepared materials were characterized using a number of analytical techniques including room temperature powder X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) theory, and UV–Visible spectroscopy to investigate the structural, morphological, optical and photocatalytic properties. No impurity phases were observed from the XRD revealing face centred cubic (FCC) crystal symmetry of the undoped and doped ceria. The formation of nanocubes was confirmed by SEM. Pore sizes in the range of 24.9–29 mm were revealed by BET analysis. A gradual increase in photodegradation efficiency with an increase in irradiation time was seen for the doped samples compared to undoped ceria, showing suitability for photocatalytic applications. An increase in defect concentrations especially for Sr2+ doped samples indicated by the quantitative analysis of Raman spectra reveals potential for electrolytic applications in fuel cells provided necessary conductivity and long-term performance testing would need to be done.

The structural and optical properties of PVA/CMC copolymer cured by UV irradiation for different times

Poly(vinyl alcohol) (PVA)/carboxymethylcellulose (CMC) blend films with equal amounts (0.25 g) of both polymers were prepared through a simple and low-cost comparative casting method. Then, the PVA/CMC blend films were exposed to ultraviolet (UV) radiation for varied time intervals (1, 12, 26, 32, 40 and 48 h). The UV-irradiation effect on the physical properties of as-prepared films, including the structure, morphology, composite and optical properties (transmittance, absorbance and band gap (E g)), was examined. Field-emission scanning electron microscopy images showed that UV irradiation had a strong effect on the shape of PVA/CMC blend films. The X-ray diffraction patterns showed various crystalline qualities in the microstructure of as-synthesized samples. The Fourier transform infrared spectra showed that the UV-irradiation time and CMC film had a positive impact on the blend polymer structure since covalent connections were formed between CMC and PVA. Furthermore, the analysis results of optical inspections showed that the absorbance of the PVA/CMC films improved with an increment in irradiation time from 1 to 40 h. Important tuning of the E g values of blend films was realized. It showed a slight increase from 4.64 to 4.84 eV with increasing irradiation time from 1 to 40 h. The E g value (3.21 eV), however, displayed an inverted behavior due to an increased irradiation time of 48 h. This reduction could be ascribed to the creation of defects inside the blend band gap. Finally, the physical property modification of PVA/CMC blend film using UV irradiation made it an amazing contender in the optoelectronic field.

Radiation tests of a CubeSat OBC

Nano-satellites, which are following the CubeSat standard have established for demanding industrial and scientific applications with critical requirements on reliability and radiation tolerance. The employment of commercial off-the-shelf components enables a state-of-the-art performance but requires extensive testing to avoid and mitigate malefunctions due to the space environment. The CubeSat mission CLIMB is representative for future missions with a complex payload, a high power budget and a harsh radiation exposure. For this reason, a comprehensive irradiation study of its on-board-computer was done. The total ionizing dose damage of 50krad was evaluated at a 60Co source. As a consequence of this test, specific components were exchanged before performing single event effect studies at the synchrotron accelerator MedAustron. A board-level test revealed that the majority of effects concern the central micro controller wherefore was followed by a component-level test. Those irradiation tests make use of a pencil beam to map the device under test, which provides additional information to localize effects - by the timestamp - at the expense of an increased irradiation time compared to a homogeneous exposure. In this paper, we summarize the major findings of the test campaign and mitigation means and present a procedure for single event effect studies at medical accelerators.

Effect of Picosecond Laser Irradiation on the Properties of Nanostructured Zinc Oxide Thin Films

In this article, a picosecond laser source was employed to irradiate the nanostructured ZnO thin film prepared by the sol-gel method. The impact of laser irradiation on the characteristics of a nanostructured ZnO thin film was investigated. Analysis using X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy confirmed a significant influence on the structure of the ZnO thin film. As the duration of laser irradiation (the number of laser pulses) increased, there was a remarkable decrease in both the electronic and photoluminescence intensities of the nanostructured film. Tauc's plot indicates a noticeable change in the optical band gaps of the thin film with the increase in irradiation time. The morphological image suggests that the laser irradiation energy induces both degradation and modification of the film surface, consequently causing changes in the structural, absorption, and photoluminescence properties of nanostructured ZnO. The observed effects are attributed to alterations in the crystal structure and size of the nanostructured ZnO film, as confirmed by XRD. The reduction in photoluminescence intensity observed over the laser irradiation times may be a result of potential degradation in the crystalline structure of the nanostructured ZnO film.

UV-Radiation and TiO2 Nanoparticles Effects on Physical Properties of PVA/CMC/TiO2 Nanocomposite Films

Fabrication of nanocomposite films of polyvinyl alcohol/carboxymethyl cellulose (PVA/CMC) blended with Titanium dioxide nanoparticles (TiO2 NPs) by a modest solution casting technique is investigated. Also, TiO2 NPs and UV-irradiation effects for different intervals (12, 26, 40, and 48 hours) on the morphology (FESEM), structure (XRD), composition (FTIR) and optical properties (UV-Vis) of as-prepared films are inspected. FESEM images display that the morphology of PVA/CMC/TiO2 nanocomposite films is altered due to the strong influence of TiO2 NPs and UV exposure. The XRD spectra indicate that the amorphous phase of the samples has changed (decline or enhancement) due to UV exposure. The FTIR spectra demonstrate that the UV-irradiation period had a favourable impact on polymer structure by exhibiting some interesting IR peaks. Furthermore, the UV-Vis examination illustrates that the increased UV-irradiation times (12 h to 40 h) and TiO2 NPs addition improved the absorption intensity of the as-prepared films. Interestingly, the Energy gap Eg of the nanocomposite films was tuned from 4.47 eV to 5.01 eV with increased irradiation time (12 h to 40 h). In contrast, due to a higher increased UV-irradiation time of 48 h, the Energy gap Eg value of nanocomposite film was decreased to 4.62 eV. That can be attributed to the strong effect of UV exposure, which influenced the creation of structural defects. Finally, these findings prove that the PVA/CMC/TiO2 nanocomposite films have an amazing chance to be used in important optoelectronic applications.

Evaluation of quantification methods to determine photodynamic action on mono- and dual-species bacterial biofilms.

The effect of photodynamic inactivation (PDI) sensitized by 5,10,15,20-tetra(4-N,N,N-trimethylammoniophenyl)porphyrin (TMAP4+) on different components of mono- and dual-species biofilms of Staphylococcus aureus and Escherichia coli was determined by different methods. First, the plate count technique showed that TMAP4+-PDI was more effective on S. aureus than E. coli biofilm. However, crystal violet staining revealed no significant differences between before and after PDI biofilms of both bacteria. On the other hand, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method indicated a reduction in viable cells as the light exposure time increases in both, mono- and dual-species biofilms. Furthermore, it was determined that as the irradiation time increases, the amount of extracellular polymeric substances present in the biofilms decreased. This effect was presented in both strains and in the mixed biofilm, being more evident in S. aureus mono-specie biofilm. Finally, scanning electron microscopy analysis showed a decrease in the number of cells forming the biofilm after photosensitization treatments. This information makes it possible to determine whether the photodynamic action is based on damage to metabolic activity, extracellular matrix and/or biomass, which may be useful in establishing a fully effective PDI protocol for the treatment of microorganisms growing as biofilms.

Structural properties and low-temperature NH3-SCR activity of CeO2-MnOx mixed oxides catalyst in the microwave field

The NH3-SCR technology, based on CeO2-MnOx catalysts, is of great significance for NOx removal at low temperatures. Microwave irradiation, as an effective heating approach, can enhance the low-temperature NH3-SCR activity of catalysts. Herein, the structure-activity relationship of CeO2-MnOx oxides catalysts was explored under microwave irradiation. The MnOx catalyst and Ce-Mn(1:1) mixed oxide catalyst exhibited good low-temperature de-NOx performance in the microwave field. With the increase of microwave irradiation intensity and time, the structure and phase composition of MnOx material underwent significant changes. CeO2 played a key role in maintaining the structural stability of the Ce-Mn(1:1) catalyst. In addition, microwave irradiation affected the redox properties and acidity of the catalyst, regulating the catalytic performance. Suitable microwave operation conditions were conducive to increasing the number of acidic sites and enhancing the redox properties, which improved the low-temperature catalytic activity of the catalyst.

The Comminution of Chert Gravel by Microwave Irradiation

Chert, a by-product rock of sand quarrying, has historically posed economic challenges for aggregate production, resulting in significant “waste” accumulation in quarries. Our study investigates the effect of microwave irradiation on the mechanical properties of chert gravel, a mineralogically homogenous material composed of fine quartz grains. The results, which demonstrate that increased irradiation time leads to a substantial decrease in chert gravel strength (by a factor of 4–6 for 2.5 min of irradiation), underscore the potential impact of this research on comminution processes. With quenching altering the fractional content of the samples after the crushing test, reducing the Gravel-to-Sand ratio, this study is driven by the promising potential of crushed chert gravel as a pivotal aggregate within the concrete and asphalt industries, offering a practical solution to their material needs. The urgent need to rehabilitate previously utilized quarry areas, offering an environmentally beneficial solution for which we all should be responsible, motivated the present study.

Exploring the role of impedance spectroscopy in assessing 405nm laser-induced inactivation of saccharomyces cerevisiae.

Impedance spectroscopy was employed to assess the electrical properties of yeast following 405nm laser irradiation, exploring the effects of visible, non-ionizing laser-induced inactivation as a more selective and safer alternative for photoinactivation applications compared to the use of DNA targeting, ionizing UV light. Capacitance and impedance spectra were obtained for yeast suspensions irradiated for 10, 20, 30, and 40min using 100 and 200 mW laser powers. Noticeable differences in capacitance spectra were observed at lower frequencies (40Hz to 1kHz), with a significant increase at 40min for both laser powers. β-dispersion was evident in the impedance spectra in the frequency range of 10kHz to 10MHz. The characteristic frequency of dielectric relaxation steadily shifted to higher frequencies with increasing irradiation time, with a drastic change observed at 40min for both laser powers. These changes signify a distinct alteration in the physical state of yeast. A yeast spot assay demonstrated a decrease in cell viability with increasing laser irradiation dose. The results indicate a correlation between changes in electrical properties, cell viability, and the efficacy of 405nm laser-induced inactivation. Impedance spectroscopy is shown to be an efficient, non-destructive, label-free method for monitoring changes in cell viability in photobiological effect studies. The development of impedance spectroscopy-based real-time studies in photoinactivation holds promise for advancing our understanding of light-cell interactions in medical applications.

Long afterglow (LAG) photoluminescence effect in ce-doped optical fiber

Ce-doped optical fibers were irradiated with various light sources, which are purple, blue, green, and red LEDs, for 30 minutes to investigate their long-after glow (LAG) characteristics. Photons were counted with a photo-multipliers tube (PMT) for 30 min, depending on the time immediately after irradiation. Depending on the wavelength of the LED, the maximum count was obtained as a result of excitation with a purple LED. The glow time was found to be about 90 minutes. The photon counting was performed for 30 minutes to characterize the irradiation time effect, depending on the irradiation time (2, 5, 10, and 30 minutes) with the purple LED. Consequently, the glow intensity and duration increased due to increased irradiation time. Additionally, the Ce-doped optical fibers were irradiated with a fluorescent lamp for 30 and 60 minutes and direct sunlight for 30 minutes. All results were fitted by a function that obtained decay time parameters. The decay times increase as the better LAG characteristics and the results confirm the decay times increase.

Accelerating Wound Healing with Combinatorial Therapy Using Natural Melanin Nanoparticle‐Polyvinyl Alcohol Blend and Core‐Sheath Hybrid Nanofibers under UV‐A Irradiation

AbstractWound healing can be a complex and slow process for the human body, particularly if it is chronic. Photothermal therapy (PTT) and photodynamic therapy (PDT) can be used to accelerate wound healing. As opposed to current PDT studies using well‐known photosensitizers, this work use novel polyvinyl alcohol (PVA) and melanin nanoparticles (MNPs) containing hybrid nanofibers prepared by electrospinning techniques to enhance wound healing with/without UV light. Blend and core‐sheath nozzles are utilized to obtain sustainable and biocompatible MNP‐PVA blend, and core‐sheath hybrid nanofibers and 30, 60, and 300 s of UV‐A irradiation are tested in terms of photoinactivation efficiencies for Escherichia coli (E. coli). The MNP‐PVA blend with a diameter of 324 nm and the core‐sheath nanofibers with a diameter of 468 nm both showed killing effect on E. coli about 41.6% and 32%, respectively, under 30 s of UV‐A irradiation. Increased irradiation time activates the protective effect of MNPs located in nanofibers, thereby decreasing photoinactivation efficiency. Moreover, the MNP‐PVA core‐sheath nanofibers with 30 s of UV‐A irradiation promote the closure of wound to 99.2% at 24 h.

Green synthesis of silica gel adsorbents: microwave boosts silanol groups for improved moisture uptake

This research investigates the influence of microwave irradiation on the silanol content and moisture adsorption capacity of silica gel prepared from clear glass waste. Employing a green and efficient microwave-assisted synthesis method, we demonstrate rapid formation of silica gel with enhanced properties. Fourier-transform infrared (FTIR) analysis confirms the presence of silanol (Si-OH) groups on the synthesized gel, with a focus on the characteristic peak at 956.44 cm⁻¹ indicating their abundance. Notably, the peak area of this peak significantly increases with increasing irradiation time (5 to 15 minutes). This translates to a parallel increase in moisture adsorption capacity, rising from 56% to 82%. The enhanced silanol content suggests the potential of microwave-derived silica gel as a high-performance desiccant, as these groups directly contribute to moisture binding. Our findings highlight the promising potential of waste glass valorization via microwave synthesis for developing sustainable and effective moisture adsorbents.

Sterilization efficacy of a homemade UV lamp system on ceramic and porcelain tiles.

Ultraviolet (UV) sterilization of Bacillus atrophaeus spores attached to eight types of tiles, consisting of combinations of ceramic and porcelain, white and black, and matte and glossy surfaces, was investigated using a homemade UV lamp system with different irradiation times (10 s, 30 s, and 60 s) and UV lamp-to-tile distances (32 mm, 76 mm, and 120 mm). The results demonstrated a reduction in colony numbers with increasing irradiation time and decreasing lamp-to-tile distance, with nearly complete sterilization observed for a 120 mm lamp-to-tile distance with 60 s UV irradiation and for a 32 mm lamp-to-tile distance with 10 s UV irradiation. Specifically, superior UV sterilization efficacy was observed on porcelain compared to ceramic tiles, on white compared to black tiles, and on matte compared to glossy tiles, consistent with the reflectance trend. In conclusion, among the tested tile surfaces, the white matte porcelain tile exhibited the most efficient UV sterilization, attributed to its highest UV reflectance.