Irradiation Source Research Articles

Nano-composite rGO-Ag-Cu-Ni mediated photocatalytic degradation of anthracene and benzene

Polycyclic aromatic hydrocarbons (PAHs) are omnipresent, persistent, and carcinogenic pollutants continuously released in the atmosphere due to the rapid increase in population and industrialization worldwide. Hence, there is an ultimate rise in concern about eliminating the toxic PAHs and their related aromatic hydrocarbons from the air, water, and soil environment by employing efficient removal technologies using nanoparticles as a catalyst. Here, the degradation of selective PAHs viz., anthracene and benzene using laboratory synthesized rGO-Ag-Cu-Ni nanocomposite (catalyst) was studied. Characterization studies revealed the nanocomposites exhibited surface plasma resonance at 350 - 450 nm, confirming the presence of Ag, Cu, and Ni metal ions embedded on the reduced graphene substrate. It was found that the nanocomposites synthesized were spherical, amorphous in nature, and aggregated together with measurements ranging from 423 to 477 nm. An SEM-EDX analysis of the nanocomposite demonstrated that it contained 25.13% O, 14.24% Ni, 27.79% Cu, and 32.84% Ag, which confirms the synthesis of the nanocomposite. Crystalline, sharp nanocomposites of average size 17–41 nm with an average diameter of 118.5 nm (X-ray diffraction and DLS) were observed. FTIR spectra showed that the nanocomposites had the functional groups alkanes, alkenes, alkynes, carboxylic acids, and halogen derivatives. Batch adsorption studies revealed that the maximum degradation achieved at optimum nano-composite concentration of 10 μg/mL, pH value of 5, PAHs concentration of 2 μg/mL and effective irradiation source being UV radiations in the case of both benzene and anthracene pollutants. The degradation of benzene and anthracene followed Freundlich & Langmuir isotherm with the highest R2 value of 0.9894 & 0.9885, respectively. Adsorption kinetic studies under optimum conditions revealed that the adsorption of both benzene and anthracene followed Pseudo-second order kinetics. Antimicrobial studies revealed that the synthesized nano-composite exhibited potential antimicrobial activity against Gram positive bacterium (Bacillus subtilis, Staphylococcus aureus), Gram negative bacterium (Klebsiella pneumonia, Escherichia coli) and fungal strain (Aspergillus niger) respectively. Thus, the synthesized rGO-Ag-Cu-Ni nano-composite acts as an effective antimicrobial agent as well as a PAHs degrading agent, helping to overcome antibiotics resistance and to mitigate the overgrowing PAHs pollution in the environment.

Biofilm prevention in the generator of a direct drive wave energy converter

Power take off in a wave energy converter has a number of unique requirements. It must convert low speed oscillating motion into electricity in a reliable, low maintenance manner. A direct drive system, where the electrical machine is optimised to operate at low speed, has the potential to offer a mechanically robust and simple solution. Similar to a hydraulic power take off, the only regular maintenance would be to inspect and replace the seal between moving parts. One strategy for removing regular maintenance is to have an unsealed system, i.e. one where sea water is allowed throughout the electrical machine. A fully flooded electrical machine has benefits in terms of cooling, but poses challenges relating to reliability, corrosion, biofouling and lubrication.
 Biofilm refers to a thin layer of fouling organisms which can interfere with the operation of components. Recent work has found that submerged surfaces can be kept free of biofouling using projected ultraviolet (UV) light from LEDs. This paper discusses the testing procedure and impact of the UVC irradiation on biofilm prevention within the active part of an electric generator in a systematic manner, with a view to accelerate its translation to full-scale applications.
 A prototype generator is being developed which will be installed in the North Sea, consisting of a submerged linear tubular electrical machine. A magnetic tubular translator will oscillate within a cylinder that houses stator coils. Lubrication will be by way of solid polymer bearings. In order that the active part of the electrical machine can oscillate smoothly, it is imperative that biofilm is prevented from colonising on the bearing surface, which also makes up the magnetic gap of the electrical machine.
 The system will have a slow reciprocating oscillation, with a peak speed of perhaps 2m/s. For most wave energy converters there will be brief static periods twice in every wave, and in calm seas these could be prolonged to several hours or even days. In low energy sea states oscillation amplitude could be less than the fully rated amplitude, meaning different parts of the bearing surface could be exposed for different amounts of time.
 Early-stage work is underway to investigate the use of UV irradiation in the active part of the electrical machine and bearing surface as biofilm prevention. Flat panels (600mm x 220mm) are used to simulate the original surfaces between moving parts. To achieve biofilm growth, an artificial slime farm was deployed which allows test panels to be subjected to a continuous dynamic flow. The light source of UV irradiation was provided by Light Emitting Diodes (LEDs) with 278nm wavelength. The effectiveness of the biofilm prevention by UVC were evaluated by Image Analysis
 The results indicate that UVC can significantly control biofilm presence on the panels. It also has demonstrated that intermittent UV can achieve successful biofilm prevention on submerged surfaces. However, observations indicate the actual UVC light intensity may perform below the manufacturer’s specifications, and this could lead to a detrimental effect on its biofilm control performance.

The variability of the quantitative traits of flax plants obtained by induced mutagenesis

Induced mutagenesis has proven to be a flexible method, functional and ready to use for any culture, moreover, it is a low-cost technology. With the ability to grow new mutant varieties with very high productive potential. To investigate the mutagenic effect of gamma (γ) irradiation, flax seeds of the three selected varieties (Kaufmann, Dichl 8, Belinka) were treated with four doses 400, 500, 600 and 700 Gy, using the 60Co-γ isotope as an irradiation source. Along the way, the phenological phases of development and evaluation of morphological parameters were miniaturized. From the analysis of multiple parameters, it was observed that the 400 Gy irradiation dose was the most effective and showed the widest phenotypic variability, and the 700 Gy less effective.

The rate constants KOH+S with some antibiotics determination by the competetive inhibitors method

Advanced oxidation processes (AOP) are widely used for the degradation of antibiotics and other micropollutants in surface and waste waters. The degree of degradation of a drug by an AOP can be predicted from the rate constant of the interaction of hydroxyl radicals with the substrate - KOH+S value, as well as from other physicochemical properties accompanying the degradation processes, and therefore these factors are important for the design of technological schemes of treatment of polluted water. Moreover, a substrate withKOH+S value known can be used to evaluate the applicability and efficiency of AOP and elucidate the kinetics and degradation mechanism of the given pollutant. In this work, the rate of the oxidation of N,N-Dimethyl-p-nitrosoaniline (PNDMA) during the photolysis of hydrogen peroxide in distilled water and in the presence of different amounts of polluted water (aqueous solutions containing sulfonamides – acetazolamide (AC) and phthalylsulfathiazole (FL), fluoroquinilones - moxifloxacin (MOX) and ciprofloxacin (CPF) as pollutants) in the UV - H2O2 systems was studied. The concentration of the drugs varied between 2.5 mg/L and 25 mg/L. The ,,ДРТ-1000” high-pressure mercury vapor lamp as the irradiation source was used. Using competitive acceptors method and based on the kinetic curves, the interaction constants of •OH radicals with the mentioned drugs were determined: kOH+AC = 8.5 ×109 L/mol×s; kOH+FL = 8.5×109 L/mol×s; kOH+MOX = 1.42×109 L/mol×s; kOH+CPF = 6.3×109 L/mol×s and the inhibiting capacity of natural waters Σ ki[Si] in the selfpurification process in the model systems used. The calculated values of the respective constants are varies between (5.4-17.7)×106 s-1.

Instant Detection of Synthetic Cannabinoids on Physical Matrices, Implemented on a Low-Cost, Ultraportable Device.

Synthetic cannabinoids (SCs) make up a class of novel psychoactive substances (NPS), used predominantly in prisons and homeless communities in the U.K. SCs can have severe side effects, including psychosis, stroke, and seizures, with numerous reported deaths associated with their use. The chemical diversity of SCs presents the major challenge to their detection since approaches relying on specific molecular recognition become outdated almost immediately. Ideally one would have a generic approach to detecting SCs in portable settings. The problem of SC detection is more challenging still because the majority of SCs enter the prison estate adsorbed onto physical matrices such as paper, fabric, or herb materials. That is, regardless of the detection modality used, the necessary extraction step reduces the effectiveness and ability to rapidly screen materials on-site. Herein, we demonstrate a truly instant generic test for SCs, tested against real-world drug seizures. The test is based on two advances. First, we identify a spectrally silent region in the emission spectrum of most physical matrices. Second, the finding that background signals (including from autofluorescence) can be accurately predicted is based on tracking the fraction of absorbed light from the irradiation source. Finally, we demonstrate that the intrinsic fluorescence of a large range of physical substrates can be leveraged to track the presence of other drugs of interest, including the most recent iterations of benzodiazepines and opioids. We demonstrate the implementation of our presumptive test in a portable, pocket-sized device that will find immediate utility in prisons and law enforcement agencies around the world.

Inactivation of E. coli and S. aureus by novel binary clay/semiconductor photocatalytic macrocomposites under UVA and sunlight irradiation

The disinfection efficiency of several novel photocatalytic macrocomposites made of Ecuadorian clay mixed with two semiconductor materials (TiO2, ZnO) has been evaluated with Staphylococcus aureus and Escherichia coli as target bacteria. They have been tested under two irradiation sources (UVA lamp and sunlight) in different configurations. Two different semiconductor/clay ratios (60/40 and 80/20) were tested at 10–20 g·L–1 (with UVA) and 20–40 g·L–1 (with sunlight) composite loadings. With the presence of the photocatalyst, a four- to five-fold increase in the inactivation rate by UVA was observed with respect to single UVA inactivation, while the performance with sunlight reaches up to six-fold. The particular effect of nature, ratio and loading on the inactivation kinetics depends on the specific bacterial species tested. In this case, the inactivation of S. aureus was faster in comparison with E. coli, probably due to the interaction between bacteria and the catalytic material and the associated ζ-potential. In general, the 80% ZnO composites at maximum loading show the highest efficiency, comparable to that of nanosized semiconductors. The ability of these composites to maintain a high disinfection efficiency after three uses, together with their low cost and ease of recovery, make these composites an attractive option for wider use in water disinfection facilities.

The comparison of surface, structural, electrical and mechanical modification of Al alloy after ablation under vacuum and oxygen environments

The present study deals with comparison of surface, structural, mechanical and electrical modifications of Al-alloy 2024 after laser ablation under vacuum and oxygen. Nd: YAG laser (532 nm, 6 ns, 10 Hz) was used as irradiation source at various fluences ranging from 58.48 J/cm2 to 293.39 J/cm2 to irradiate Al-alloy 2024. Using an optical microscope, depth profilometry was used to determine the ablation depth and ablated volume of the irradiated Al-alloy 2024 target. The surface topography explored by Scanning Electron Microscope (SEM) analysis confirms the formation of some common features such as melt pools, ridges, pores and cavities under both environments. The surface structures are suppressed and porous under oxygen environment as compared to vacuum. Energy-dispersive X-ray spectroscopy study confirms the oxide formation in O2 ambient environment. The structural modifications explored by XRD analysis, confirm the formation of Al2O3 phase only at the lowest laser fluence of 58.48 J/cm2 in O2. Williamson–Hall analysis of X-ray diffraction patterns was used to determine structural parameters like as crystallite size, dislocation line density and lattice strain. The modifications in electrical and mechanical properties after laser irradiation have been explored by the four-point probe method and the Vicker micro hardness testing technique respectively. A decreasing trend of electrical conductivity is obtained in both environments. However, a decrement in electrical conductivity up to 5.4 × 105 S/cm is observed under oxygen as compared with the vacuum. Surface microhardness increases monotonically in both environments as a function of laser fluence which is attributed to variations in dislocation densities and increased in laser induced ablation pressure and shock pressure.

Effect of Terminal Alkyl Chains for Free Radical Photopolymerization Based on Triphenylamine Oxime Ester Visible‐Light Absorbing Type I Photoinitiators

AbstractIn order to investigate the photopolymerization properties of the alkyl chain length dependence Type I photoinitiators, in this study, a series of visible‐light‐absorbing triphenylamine oxime esters (Peko‐A‐D, and reference TP‐1M) containing various alkyl chain length in the periphery were synthesized. That is, an alkane segment contains isopropyl for Peko‐A, butyl for Peko‐B, undecane for Peko‐C, pentadecane for Peko‐D and methyl for TP‐1M, respectively. Except for Peko‐D, all of them have good organo‐solubility and can dissolve in testing monomer (trimethylolpropane triacrylate, TMPTA). All the oxime esters give from near UV to visible‐light absorption regions with maximum absorption peaks at around 360 nm and show rather red‐shifted compared to the commercial OXE‐01 compound. Accordingly, the photochemical reaction behavior was studied by cyclic voltammograms (CV), electron spin resonance (ESR) and steady‐state photolysis. In addition, the oxime esters based photoinitiating systems are studied through photo‐DSC experiment based on various light exposure wavelengths (UV lamp, LED@365 nm and LED@405 nm). Under different light source, the penetration affects the final double conversion efficiencies. As a result, all the oxime esters‐based formulation shows better double conversion efficiencies upon LED@405 nm as an irradiation source. Finally, the new oxime ester photoinitiating system was capable applied in direct laser write to generate 3D patterns using a laser diode @405 nm.

Laser-assisted plasma formation and ablation of Cu in a controlled environment

In this paper, we explore the surface and mechanical alterations of Cu, as well as the parameters of laser-assisted plasma and ablation. The irradiation source is a Nd: YAG laser with a constant irradiance of 1.0 GW/cm2 (1064 nm, 55 mJ, 10 ns, 10 Hz). Physical parameters such as electron temperature (Te) and electron number density (ne), sputtering yield (yield), ablation depth (depth), surface morphology (morphology), and hardness (Vickers) of laser irradiated Cu are evaluated using instruments such as a Laser Induced Breakdown Spectrometer (LIBS), Quartz Crystal Microbalance (QCM), Optical Emission Microscope (OEM), Scanning Electron Microscope (SEM), and Vicker's hardness tester. These physical characteristics have been studied in relation to changes in pressure (from 10 torr to 100 torr) and the composition of two inert ambient gases (Argon and Neon). Pressures of Ar and Ne are found to enhance the emission intensities of spectral lines of Cu, Te, and ne, as well as the sputtering yield, crater depth, and hardness of laser ablated Cu, to a maximum at 60 torr, after which they decrease with subsequent increases in pressure up to 100 torr. Increases in pressure up to 60 torr are connected with plasma confinement effects and increased collisional frequency, whereas decreases in pressure between 60 and 100 torr are ascribed to shielding effects by the plasma plume. All numbers are also found to be greater in Ar compared to Ne. In Ar, laser-ablated Cu reaches a maximum of 15218 K, 1.83 × 1018 cm−3, 8.59 × 1015 atoms/pulse, 231 m, and 147 HV, whereas in Ne, it reaches a maximum of 12000 K, 1.75 × 1018 cm−3, 7.70 × 1015 atoms/pulse, 200 m, and 116 HV. Ar is more likely than Ne to develop surface features such as craters, distinct melting pools with elevating edges, flakes, cones, etc. It is also shown that there is a significant association between the outcomes, with an increase in Te and ne being responsible for a rise in sputtering yield, ablation depth, surface morphology, and surface hardness. These findings have potential uses in plasma spectroscopy for materials science and in industrial applications of Cu.

Radiation-induced double-strand breaks by internal ex vivo irradiation of lymphocytes: Validation of a Monte Carlo simulation model using GATE and Geant4-DNA

This study describes a method to validate a radiation transport model that quantifies the number of DNA double-strand breaks (DSB) produced in the lymphocyte nucleus by internal ex vivo irradiation of whole blood with the radionuclides 90Y, 99mTc, 123I, 131I, 177Lu, 223Ra, and 225Ac in a test vial using the GATE/Geant4 code at the macroscopic level and the Geant4-DNA code at the microscopic level. MethodsThe simulation at the macroscopic level reproduces an 8 mL cylindrical water-equivalent medium contained in a vial that mimics the geometry for internal ex vivo blood irradiation. The lymphocytes were simulated as spheres of 3.75 µm radius randomly distributed, with a concentration of 125 spheres/mL. A phase-space actor was attached to each sphere to register all the entering particles. The simulation at the microscopic level for each radionuclide was performed using the Geant4-DNA tool kit, which includes the clustering example centered on a density-based spatial clustering of applications with noise (DBSCAN) algorithm. The irradiation source was constructed by generating a single phase space from the sum of all phase spaces. The lymphocyte nucleus was defined as a water sphere of a 3.1 µm radius. The absorbed dose coefficients for lymphocyte nuclei (dLymph) were calculated and compared with macroscopic whole blood absorbed dose coefficients (dBlood). The DBSCAN algorithm was used to calculate the number of DSBs. Lastly, the number of DSB∙cell−1∙mGy−1 (simulation) was compared with the number of radiation-induced foci per cell and absorbed dose (RIF∙cell−1∙mGy−1) provided by experimental data for gamma and beta emitting radionuclides. For alpha emitters, dLymph and the number of α-tracks∙100 cell−1∙mGy−1 and DBSs∙µm−1 were calculated using experiment-based thresholds for the α-track lengths and DBSs/track values. The results were compared with the results of an ex vivo study with 223Ra. ResultsThe dLymph values differed from the dBlood values by −1.0% (90Y), −5.2% (99mTc), −22.3% (123I), 0.35% (131I), 2.4% (177Lu), −5.6% (223Ra) and −6.1% (225Ac). The number of DSB∙cell−1∙mGy−1 for each radionuclide was 0.015 DSB∙cell−1∙mGy−1 (90Y), 0.012 DSB∙cell−1∙mGy−1 (99mTc), 0.014DSB∙cell−1∙mGy−1 (123I), 0.012 DSB∙cell−1∙mGy−1 (131I), and 0.016 DSB∙cell−1∙mGy−1 (177Lu). These values agree very well with experimental data. The number of α-tracks∙100 cells−1∙mGy−1 for 223Ra and 225Ac where 0.144 α-tracks∙100 cells−1∙mGy−1 and 0.151 α-tracks∙100 cells−1∙mGy−1, respectively. These values agree very well with experimental data. Moreover, the linear density of DSBs per micrometer α-track length were 11.13 ± 0.04 DSB/µm and 10.86 ± 0.06 DSB/µm for 223Ra and 225Ac, respectively. ConclusionThis study describes a model to simulate the DNA DSB damage in lymphocyte nuclei validated by experimental data obtained from internal ex vivo blood irradiation with radionuclides frequently used in diagnostic and therapeutic procedures in nuclear medicine.

PERTUMBUHAN TANAMAN KEDELAI (GLYCINE MAX L.) HASIL RADIASI SINAR GAMMA CESIUM-137

The study of the Effect of Cesium-137 Gamma Ray Radiation on the Growth of Soybean Plants (Glycine max L.) aims to determine the quality of growth of soybean plants (Glycine max L.). The Cesium-137 source was used as a source of irradiation in the study, with a constant distance (x) of irradiation of 100 cm from the wall, with dose variations of 0 Control, 25 mGy, 50 mGy, 75 mGy, 100 mGy and 120 mGy. The method used in this research is descriptive statistical analysis. The samples used in this research are soybean seeds from the Langkowa Soybean plantation, Tonasa Village, Tombolopao Subdistrict and packaged soybeans taken from the packaging seeds of Flower Seed Shop Jl. Veteran Selatan No.395. The results of this study showed that the sprout growth time with a dose treatment of B5 (75 mGy) took 9 days to grow, the percentage of stem height (cm) at a dose of B5 (75 mGy) the average stem height was 3.7 cm, the percentage of leaf width (cm) at a dose of B4 (100 mGy) the average leaf width was 2.9 cm, the percentage of the number of leaves (sheets) at a dose of B3 (75 mGy) the average number of leaves was 4 sheets. The use of Cesium-137 and Cobalt-60 Gamma radiation in plant breeding can be utilised on various types of plants to increase plant cultivation and better production results.

Photochemistry of the Fe(III)-iminodiacetic acid complex under UVA and UV/Vis irradiation: synthesis and characterisation

ABSTRACT The photochemistry of Fe(III)-Iminodiacetic acid complex (Fe(III)-IDA) was studied under UVA and UV/Vis irradiation. The synthesis was realised via molar ratio method modified by reaction of IDA as ligand with Fe(III) as metal. The interaction of Fe(III) with IDA was characterised using Fourier-transform infrared (FTIR) and spectroscopy UV–visible. The results confirmed the stability of the complex at pH > 5; with constant of stability (Log β = 10.02) and stoichiometry Fe(III): IDA = 1:1. In addition, the redox potential was calculated at 521 mV, which is significantly lower than E° for the Fe(III)/Fe(II) couple. The photolysis of this complex in the presence of UVA light and UV/Vis light at different pHs was carried out. This photolysis was followed by several assay Fe(II) and •OH. The results show that the Fe(III)-IDA complex present a photo-reactivities under either light source and the phenomenon is faster when the UV/Vis was used. The initial conversion rate (r0) decreased with increasing of initial pH. The formation of hydroxyl radicals via the Fenton reaction was improved at pH = 2.12 for both irradiation sources used. Reduction of total organic carbon was also studied using the total organic carbon (TOC). The feasibility of amino iron complexes to improve the Fenton process under irradiation was confirmed. Additionally, our research also evidenced the optimal conditions for the formation of hydroxyl radicals; which are the key factor in remove pharmaceuticals pollutants in aqueous media. Based on the results obtained, the Fe(III)-IDA complex could be efficiently photolysis under UV/Vis light.

3H‐Phenothiazin‐3‐one: A Photocatalyst for the Aerobic Photochemical Oxidation of Sulfides to Sulfoxides

AbstractIn this study, 3H‐phenothiazin‐3‐one is identified as a photocatalyst for the photochemical oxidation of sulfides to sulfoxides. This photocatalytic method uses a low catalyst loading (0.05 mol%), molecular oxygen as the sole oxidant, and a blue LED lamp as the irradiation source. It can be applied to the oxidation of both alkyl‐aryl and alkyl‐alkyl sulfides. Moreover, the method is also applicable in the synthesis of the known pharmaceutically active compounds Modafinil and Sulforaphane.

Sunlight-assisted photocatalytic degradation of tartrazine in the presence of Mg doped ZnS nanocatalysts

In this work, Mg2+ doped ZnS nanoparticles were prepared by solvothermal method, using ethanol as solvent at 135 °C.The nanoparticles were characterized by XRD, SEM, UV–vis and PL. After doping, XRD revealed a reduction in lattice parameter, confirming Mg2+ substitution into the ZnS host lattice. The UV–vis study indicated that the incorporation of Mg2+ ions does not modify the band gap width of the nanoparticles. The PL spectra measured at 325 nm excitation wavelength, reveals that the photogenerated electrons of Zn0·9Mg0·1S have a slower recombination rate than ZnS nanoparticles. The XPS finding confirm that the chemical environment of the elements has been affected by the presence of the Mg2+. The Valence Band Maximum (VBM) was determined to be 0.2eV for ZnS and 1eV for Zn0·9Mg0·1S, respectively. These findings confirm the perturbation of electronic properties when Mg2+ is added to the ZnS. The photocatalytic ability was estimated through the degradation of tartrazine under natural-sunlight irradiation. Zn0.9Mg0.1S shows a high photocatalytic activity, compared to ZnS nanoparticles. The photocatalytic degradation was studied through different parameters, such as: the source of irradiation, the pH, the dye concentration, the catalyst concentration, and the recyclability. The degradation investigation shows that tartrazine is better oxidized at free pH = 6,7, with a dye concentration of 20 mg/L and a catalyst dosage of 1 g/L. Zn0.9Mg0.1S degraded 98% of tartrazine under natural-sunlight irradiation. In addition, the catalyst retained a good photo-degradation capacity, even after many treatment cycles. The scavengers study confirmed that the main active species responsible for the photocatalytic degradation of tartrazine were the oxidation groups (O2•-).

Red-Light-Photosensitized NO Release and Its Monitoring in Cancer Cells with Biodegradable Polymeric Nanoparticles.

The role of nitric oxide (NO) as an "unconventional" therapeutic and the strict dependence of biological effects on its concentration require the generation of NO with precise spatiotemporal control. The development of precursors and strategies to activate NO release by excitation in the so-called "therapeutic window" with highly biocompatible and tissue-penetrating red light is desirable and challenging. Herein, we demonstrate that one-photon red-light excitation of Verteporfin, a clinically approved photosensitizer (PS) for photodynamic therapy, activates NO release, in a catalytic fashion, from an otherwise blue-light activatable NO photodonor (NOPD) with an improvement of about 300 nm toward longer and more biocompatible wavelengths. Steady-state and time-resolved spectroscopic and photochemical studies combined with theoretical calculations account for an NO photorelease photosensitized by the lowest triplet state of the PS. In view of biological applications, the water-insoluble PS and NOPD have been co-entrapped within water-dispersible, biodegradable polymeric nanoparticles (NPs) of mPEG-b-PCL (about 84 nm in diameter), where the red-light activation of NO release takes place even more effectively than in an organic solvent solution and almost independently by the presence of oxygen. Moreover, the ideal spectroscopic prerequisites and the restricted environment of the NPs permit the green-fluorescent co-product formed concomitantly to NO photorelease to communicate with the PS via Förster resonance energy transfer. This leads to an enhancement of the typical red emission of the PS offering the possibility of a double color optical reporter useful for the real-time monitoring of the NO release through fluorescence techniques. The suitability of this strategy applied to the polymeric NPs as potential nanotherapeutics was evaluated through biological tests performed by using HepG2 hepatocarcinoma and A375 melanoma cancer cell lines. Fluorescence investigation in cells and cell viability experiments demonstrates the occurrence of the NO release under one-photon red-light illumination also in the biological environment. This confirms that the adopted strategy provides a valuable tool for generating NO from an already available NOPD, otherwise activatable with the poorly biocompatible blue light, without requiring any chemical modification and the use of sophisticated irradiation sources.

Graphene oxide/ZnO nanocomposites applied in photocatalysis of dyes: Tailoring aqueous stability of quantum dots

Nanocomposites between ZnO Quantum Dots (QDs) and Graphene Oxide (GO) were synthesized by sol-gel method in isopropanol. The proportion of GO aqueous dispersion was evaluated and ZnO QDs were also prepared with addition of water, for comparison. Indeed, the GO or water addition had a huge impact in the ZnO QDs size and photoluminescence, once the greater the GO/water addition, the greater the ZnO QDs size (from 4.5 ± 0.1–23.8 ± 0.4 nm) and the 50 µL of GO (or water) added to the synthesis led to a higher intensity emission. The photocatalytic activity of the ZnO-based materials was evaluated for methylene blue (MB) and astrazon blue (AB) degradation in isopropanol and water using two different sources of light irradiation (fluorescence and Hg vapor lamps). Once again, the GO/water addition affected their photocatalytic behavior and stability in aqueous medium. The ZnO QDs/GO had an impressive photocatalytic performance in both sources of light irradiation in isopropanol and aqueous medium (99% and 93% of degradation after 30 min of irradiation with Hg vapor lamp, respectively). In addition, the photocatalytic activity of this nanocomposite was stable when submitted up to 5 photodegradation cycles and to higher MB concentrations, besides being successfully reused in aqueous medium.

Ultraviolet photon-counting single-pixel imaging

We demonstrate photon-counting single-pixel imaging in the ultraviolet region. Toward this target, we develop a high-performance compact single-photon detector based on a 4H-SiC single-photon avalanche diode (SPAD), where a tailored readout circuit with active hold-off time is designed to restrain detector noise and operate the SPAD in the free-running mode. We use structured illumination to reconstruct 192 × 192 compressed images at a 4 fps frame rate. To show the superior capability of ultraviolet characteristics, we use our single-pixel imaging system to identify and distinguish different transparent objects under low-intensity irradiation and image ultraviolet light sources. The results provide a practical solution for general ultraviolet imaging applications.

Suitability Assessment of CsPbI_3 Dosimeter with ^192Ir Source for Brachytherapy Quality Assurance

In brachytherapy, quality assurance (QA) is a prerequisite to minimize the dose irradiation to the healthy tissues in patients during treatment, as it evaluates the accuracy of the dose applied to the patients as well as the accuracy of the position of the irradiation. Therefore, a strong emphasis has been placed on brachytherapy QA in clinical practice. This study assessed the suitability of a CsPbI3 dosimeter for the brachytherapy QA system. To verify the reliability of the unit cell sensor fabricated with CsPbI3, the electrical parameters were evaluated, after which the position dependence of the sensor was analyzed. A high level of reliability (R 2 > 0.99) and reproducibility (relative standard deviation < 1.5%) were observed. The maximal value measured at the isocenter of the sensor as the distance of the dosimeter from the irradiation source was gradually decreased. When the optimal angle was assessed, the variation was as high as 5.01 nC depending on the form of the 192Ir source. Therefore, the CsPbI3 dosimeter fabricated in this study is a suitable substitute for the conventional QA dosimeter.

Enhanced photocatalytic activity of Bi2WO6/ZnO nanocomposite in degradation of methylene blue under sunlight irradiation and for antimicrobial activity

Photocatalytic degradation of organic pollutants is crucial although this process effectively disintegrates the toxicants that pollute drinking water, which, in turn, result in environmental pollution. Orthorhombic bismuth tungstate (Bi2WO6) in combination with hexagonal zinc oxide (ZnO) effectively degrades toxic methylene blue (MB) from water, by the photocatalytic technique. Composite of Bi2WO6 nanoplates with ZnO was synthesized by the simple hydrothermal method. Raman analysis shows the presence of vibrational and functional modes present in the prepared catalysts. The obtained Bi2WO6/ZnO composite absorbed 650 nm of light and promoted an efficient photocatalytic process. The photocatalytic process was carried out for the degradation of MB under various light irradiation sources such as visible light, UV light, and sunlight (direct). The photocatalyst (50 mg of Bi2WO6/ZnO and 3.2 mg/L MB solution) provided a maximum percentage for the degradation of MB (74%) under sunlight irradiation compared to that under other light irradiation sources. Furthermore, the Bi2WO6/ZnO composite was used to analyze its antimicrobial activity, and it shows the best antimicrobial activities against both gram-positive bacteria and gram-negative bacteria such as Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Vibrio cholera.

Design and experiment of 10 kW-level laser with high-uniformity distribution and large-size output beam

A 11.5 kW laser irradiation source was established to study the pyrolysis and fire of combustibles. The high-power laser diode array (LDA) is first used in the laser irradiation source. By using the homogenized waveguide and large-aperture reshaper, we obtained the high-uniformity distribution and large-size beam simultaneously. The intensity uniformity and the beam size were 95 % and 102.3 mm respectively, correspondingly the power intensity was 1.4 MW/m2. To the best of our knowledge, this is the first time to realize the large-size high-uniformity and MW/m²-level laser irradiation source, which lays a solid foundation for the experiment of the pyrolysis and fire of combustibles induced by the light irradiation. In addition, by the innovative designs, it is effectively enhanced that the damage threshold and the thermal stability of homogenized waveguide under the high-power CW laser.