Under Ultraviolet Research Articles

Toxicity enhancement of nano titanium dioxide to Brachionus calyciflorus (Rotifera) under simulated sunlight and the underlying mechanisms

Nano titanium dioxide (nTiO2) generally shows low toxicity to organisms under light-emitting diode (LED) light. However, nTiO2 can induce production of reactive oxygen species (ROS) under ultraviolet (UV) light due to its photocatalytic activity. Therefore, it is reasonable to expect the enhancement of nTiO2 toxicity under sunlight. To test this hypothesis, we compared the toxicity of nTiO2 to Brachionus calyciflorus under simulated sunlight and LED light. The results showed that the 24 h-LC50 of nTiO2 to B. calyciflorus under LED light and simulated sunlight were 24.32 (95% CI: 14.54–46.81 mg/L) and 10.44 mg/L (95% CI: 6.74–17.09 mg/L), respectively. Compared with the blank control, treatments with nTiO2 significantly affected life-table demographic parameters, population growth parameters and swimming linear speed under both simulated sunlight and LED light. However, life expectancy, net reproductive rate, average lifespan, maximal population density, and swimming linear speed in the treatments of nTiO2 at 0.1, 1, and/or 10 mg/L showed markedly lower values under simulated sunlight than those under LED light, suggesting that simulated sunlight could enhance the toxicity of nTiO2. In addition, markedly higher catalase (CAT) activity and malondialdehyde (MDA) content but lower glutathione (GSH) content were observed in treatment with 10 mg/L nTiO2 under simulated sunlight than that under LED light. The results showed that compared with LED light, simulated sunlight significantly induced more oxidative stress in the presence of nTiO2, and the ROS production was mainly localized to the corona and digestive tract of rotifers by confocal laser scanning microscope. Exposure to 10–50 μM of vitamin C, that is an effective ROS scavenger, could rescue the swimming linear speed of rotifers to the normal level in the blank control. These results suggested that oxidative damages on cell membrane might be the vital mechanism underlying the toxicity enhancement of nTiO2 to rotifers under simulated sunlight. Thus, the previous publications under LED light may underestimate the real toxicity and environmental risk of nTiO2 in natural conditions.

Preparation and scintillation properties of Ce3+/Tb3+-co-doped oxyfluoride glass for high-resolution X-ray imaging

Scintillator glasses have the potential for X-ray imaging owing to their low production cost, controllable shape and size, and uniform ion-doping concentration. In this study, Tb3+-doped and Ce3+/Tb3+-co-doped oxyfluoride scintillator (C4T9) glass samples were fabricated by high-temperature melting and quenching. In addition, the luminescence properties of the glass samples and the discrepancy in the energy transfer mechanism between Ce3+ and Tb3+ under ultraviolet (UV) light and X-ray excitation were investigated. The C4T9 glass sample showed excellent integral scintillation efficiency of 84.1% for commercial Bi4Ge3O12 (BGO) crystals. The spatial resolution of the C4T9 glass sample was higher than that of the commercial BGO crystal with 42.29 mGy s−1 X-ray irradiation, reaching 16 lp·mm−1. C4T9 glass is expected to become a key material in medical imaging, safety inspection, industrial inspection, and other fields.

Photocatalytic Activity of the V2O5 Catalyst toward Selected Pharmaceuticals and Their Mixture: Influence of the Molecular Structure on the Efficiency of the Process.

Due to the inability of conventional wastewater treatment procedures to remove organic pharmaceutical pollutants, active pharmaceutical components remain in wastewater and even reach tap water. In terms of pharmaceutical pollutants, the scientific community focuses on β-blockers due to their extensive (over)usage and moderately high solubility. In this study, the photocatalytic activity of V2O5 was investigated through the degradation of nadolol (NAD), pindolol (PIN), metoprolol (MET), and their mixture under ultraviolet (UV) irradiation in water. For the preparation of V2O5, facile hydrothermal synthesis was used. The structural, morphological, and surface properties and purity of synthesized V2O5 powder were investigated by scanning electron microscopy (SEM), X-ray, and Raman spectroscopy. SEM micrographs showed hexagonal-shaped platelets with well-defined morphology of materials with diameters in the range of 10−65 µm and thickness of around a few microns. X-ray diffraction identified only one crystalline phase in the sample. The Raman scattering measurements taken on the catalyst confirmed the result of XRPD. Degradation kinetics were monitored by ultra-fast liquid chromatography with diode array detection. The results showed that in individual solutions, photocatalytic degradation of MET and NAD was relatively insignificant (<10%). However, in the PIN case, the degradation was significant (64%). In the mixture, the photodegradation efficiency of MET and NAD slightly increased (15% and 13%). Conversely, it reduced the PIN to the still satisfactory value of 40%. Computational analysis based on molecular and periodic density functional theory calculations was used to complement our experimental findings. Calculations of the average local ionization energy indicate that the PIN is the most reactive of all three considered molecules in terms of removing an electron from it.

Hollow-porous fiber-shaped strain sensor with multiple wrinkle-crack microstructure for strain visualization and wind monitoring

Flexible strain sensor shows great development prospects in medical treatment, human-machine interface and environmental monitoring fields due to their great flexibility, ductility, skin-mountability and excellent sensing abilities. Nevertheless, the inherent contradictions between sensitivity and sensing range limit their further development as high-performance strain sensors. To solve this challenge, a two step pre-stretching strategy was proposed in this paper. Wrinkle and crack structures on carbon nanotubes (CNTs) conductive layer were integrated into a thermoplastic polyurethane (TPU) fiber with hollow-porous structure. Benefiting from the synergistic structure of the conductive layer, the fiber-shaped strain sensor synchronously possesses a wide sensing range (up to 530 % strain), high sensitivity (gauge factor, GF up to 57.2), low detection limit (0.5 % strain) and satisfactory sensing stability and durability. The sensing mechanism was proposed based on the development of the conductive network and the wrinkle and crack microstructures in detail. Moreover, strain-dependent visualization of the sensor under ultraviolet (UV) light was realized on the basis of the good UV-shielding property of the CNTs layer and the exposure of fluorescent agent (FA) in TPU fiber during the crack propagation process. This fiber-shaped strain sensor was demonstrated for human bio-signals acquisition as well as the monitoring of wind direction, showing its broad application prospects as next generation flexible strain sensor.

Photodegradation of xylene isomers: Kinetics, mechanism, secondary pollutant formation potential and health risk evaluation

Photodegradation technology has been widely applied in the purification of industrial aromatic hydrocarbons. However, whether this technology efficiently removes the pollutants to prevent secondary pollution and health risk is still unclear. Here, the photodegradation processes of three xylenes were compared under designed reaction atmospheres and light sources. Xe lamp showed poor photodegradation ability toward xylenes, no matter in N2 or N2+O2 system, while much higher photodegradation performance of xylenes were obtained under ultraviolet (UV) and vacuum ultraviolet (VUV) irradiation, especially in N2+O2+VUV system, where 97.9% of m-xylene, 99.0% of o-xylene or 87.5% of p-xylene with the initial concentration of 860 mg/m3 was removed within 240 min. The xylenes underwent three processes of photo-isomerization, photodecomposition and photo-oxidation to produce intermediates of aromatics, alkanes and carbonyls. Among them, the photo-isomerization products showed the highest concentration percentage (e.g., ≥50% in o-xylene system), confirming that photo-isomerization reaction was the dominated photodegradation process of xylenes. Moreover, these isomerized products not only contributed about 97% and 91% to the formation potential of O3 (OFP) and secondary organic aerosols (SOAFP), but also displayed obvious non-carcinogenic risk, although one of photodecomposition product—benzene showed the highest occupational exposure risk. Therefore, the secondary pollution and health risks of photodegradation products of xylenes were non-ignorable, although the OFP, SOAFP and health risks of the generated products reduced at least 4.5 times in comparison with that of the degraded xylenes. The findings are helpful for the appropriate application of this technology in the purification of industrial organic waste gas.

Boronic acid-modified fluorescent sensor using coffee biowaste-based carbon dots for the detection of dopamine

Dopamine (DA) is an indispensable form of neurochemical, which normal levels are highly potential for maintaining proper brain functions. Their abnormal levels are threatening the neurological behavior in humans with aggressive Alzheimer’s, Parkinson’s, Huntington’s diseases, etc. Hence, in this study, a boronic acid-functionalized fluorescent sensor was developed by adapting the conveniently accessible biomass such as coffee waste for the detection of neurotransmitters like DA. In this context, we synthesized carbon dots (CDs) using coffee waste via a simple hydrothermal treatment (C-CDs). The fluorescent sensor was designed using phenylboronic acid namely 3-aminophenylboronic acid (APBA)-modification to the C-CDs through 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxy-succinimide (EDC/NHS) coupling chemistry (B-CDs). Both C-CDs and B-CDs have shown photoluminescence (PL) emission maxima around 452 and 469 nm under the excitation maxima of 335 and 371 nm, respectively. Further, their optical properties were studied through PL response, which showed the distinct excitation-dependent and independent emission behavior, when shifting the excitation wavelengths from 300–500 nm to 300–390 nm, respectively. The C-CDs and B-CDs have displayed light and strong-blue colored emissions under ultraviolet (UV)-illumination, respectively. The B-CDs have shown fluorescence quenching against DA concentrations ranging from 0 to 30 µM with a lower detection limit of 4.25 nM. The applicability of the proposed sensor was investigated in real samples like the human serum, which exhibited good recovery values of 95.9–101.35 %.

(C5N2H14)GeBr4: A 2D Organic Germanium Bromide Perovskite with Strong Orange Photoluminescence Properties

Hybrid organic-inorganic metal halide (OIMH) perovskites are regarded as potential photoluminescent (PL) materials and have attracted intensive attention. Here, we select 1-methylpiperazine as an organic component and successfully obtain a two-dimensional (2D) Ge-based OIMH perovskite, (1-mpz)GeBr4. It features a 2D layered structure composed of distorted [GeBr6]4- octahedra with organic (C5H14N2)2+ located between the layers. (1-mpz)GeBr4 exhibits strong orange color under ultraviolet (UV) light and possesses good PL stability for over 2 months. The photoluminescence quantum efficiency is measured to be 7.15% at room temperature, which is the largest among all reported low-dimensional Ge-based perovskites. Experimental measurements, combined with first-principles calculations, reveal that its PL property is attributed to self-trapped excitons (STEs) from [GeBr6]4- groups. From the deduced structure-property relationship, Ge-based OIMH PL perovskites with good stability and high PL efficiency can be expected.

A facile switch-on fluorescence sensing method for detecting phosphates from complex aqueous samples

Phosphates play an essential role in our living systems. Therefore, it is important to have simple and effective methods to detect and monitor the level of phosphates in complex samples. In this study, a facile switch-on fluorescence sensing method is developed for the detection of phosphates. The sensing probes are composed of Gd3+ and riboflavin-5′-phosphate (RFMP), which are hard acid and hard base, respectively. Gd3+ and RFMP can strongly bind via chelation once mixed. RFMP emits bright green fluorescence under ultraviolet (UV) light illumination. However, its fluorescence is quenched in the presence of Gd3+, presumably due to aggregation caused quenching. In the presence of phosphates, the fluorescence derived from RFMP on the Gd3+-RFMP can be restored owing to the competitive binding of phosphates with Gd3+ on the Gd3+-RFMP conjugates to release RFMP. In this study, we demonstrate the feasibility of using the developed sensing method to determine the level of phosphates from real world samples such as drinking water and fetal bovine serum under the illumination of a UV lamp (λmax = 365 nm) simply with the naked eye. The lowest distinguishable concentration of using our detection method towards adenosine triphosphate and pyrophosphate with the naked eye is ∼1 μM. Furthermore, when fluorescence spectroscopy is used as a detection tool, the limit of detection has further reduced to ∼611 nM. The feasibility of using the developed sensing probes combined with fluorescence spectroscopy for quantitative analysis of phosphates in real samples is also demonstrated in this study.

Aggregation and sheltering behavior of Armadillidium vulgare and Armadillidium nasatum (Isopoda: Armadillidiidae) exposed to fluorescent and ultraviolet light

Terrestrial isopods are gregarious invertebrates, aggregating in colonies. Aggregation reduces risk of predation and desiccation. Isopod aggregation and sheltering behavior have been observed under fluorescent and color-filtered light, but not under ultraviolet (UV) light. With UV levels on the rise, it is important to understand how soil ecosystems might be impacted by human-induced ozone depletion. We examined aggregation and sheltering behaviors of the terrestrial isopods Armadillidium vulgare and Armadillidium nasatum under fluorescent light and under fluorescent light with added UV light. Upon testing, each species was randomly assigned into groups of 10 individuals. Each group was released into a circular arena with a black disk in the middle of the lid which functioned to block light and served as a shelter. Sheltering and aggregation behaviors were recorded every 15 minutes for 45 minutes under the presence versus absence of increased UV light. There was no significant difference in the total number of sheltering events, but positive thigmotaxis (movement toward or away from a physical stimulus) may have influenced sheltering. However, there was a significant increase in the average number of aggregated individuals and the total number of aggregates in groups exposed to increased UV conditions, perhaps reflective of their desiccation avoidance behavior and negative phototaxis. Additionally, A. nasatum individuals were significantly more likely to form aggregates than A. vulgare when exposed to increased UV light conditions, perhaps because A. nasatum is less desiccation-resistant than A. vulgare.

Inverse Opal Photonic Crystals for Real-Time Identifiable Labels via Ultraviolet and Near-Infrared Light

In this work, we developed inverse opal photonic crystals (IOPCs) for real-time identifiable labels by tuning the structure color and chemical color under ultraviolet (UV) light and near-infrared (NIR) light. We prepared IOPCs by etching a silica photonic crystal template in thermosensitive hydrogel added to 2,2-diphenyl-2H-naphtho [1,2-b] pyran-6-carbaldehyde (NP). In this way, the transparent hydrogel turned red under UV light due to the photochromic naphthopyran. Meanwhile, the green structure color of IOPCs was superimposed with the red chemical color of the hydrogel, so that IOPCs with naphthopyran (IOPCs/NP) appeared yellow. When irradiated by NIR light, the structure color of IOPCs turned blue from green due to the volume contraction of the thermosensitive hydrogel. When irradiated by UV and NIR light simultaneously, the blue structure color of IOPCs was superimposed with the red chemical color of the hydrogel, and the IOPCs/NP would finally appear purple. Thus, we realized the real-time controllable IOPCs by two light sources. Based on this, we designed a series of identifiable labels with multiple colors under UV and NIR light, which expanded the application of information anticounterfeiting and identification.

Metal Oxide Electrospun Nanofibrous Membranes for Effective Dye Degradation and Sustainable Photocatalysis

The fabrication of metal oxide nanofibers using (titanium (IV) isopropoxide) and (tin (IV) tert-butoxide) of weight ratio 1:1 precursor in presence of poly (vinyl pyrrolidone) as a binder using a well-known electrospinning technique is reported. The average diameter of TiO2, SnO2, and composite TiO2-SnO2 nanofibers were found to be in the range 75–110 nm. The nanofibers were characterized using thermogravimetric analysis (TGA) to understand the polymer evaporation temperature and further analyzed using scanning electron microscopy (SEM) to study the morphology of the nanofibers. The oxidation states of titanium (Ti) and tin (Sn) ions were analyzed using X-ray photoelectron spectroscopy (XPS), indicating that the TiO2 undergoes a change even after loading SnO2. The photocatalytic efficiency of the composite TiO2-SnO2 fibers was investigated to study the degradation capabilities under ultraviolet (UV) light towards industrial polluting dyes such as Alcian Blue, Alizarin Red S, Bilirubin, Brilliant Blue, Bromophenol Blue, and Rhodamine B ITC. Rhodamine B showed a significant degradation rate of about 0.0064 min−1 in comparison to the other dyes.

Photocatalytic treatment as a polishing step for the degradation of bio‐recalcitrant fractions of winery wastewater under solar, UVA‐LED, and blacklight irradiation

AbstractBACKGROUNDThis study investigates, for the first time, the most beneficial conditions for photocatalytic oxidation under ultraviolet (UV) irradiation provided by either a solar simulator, UVA light‐emitting diode (UVA‐LED), or UVA blacklight lamp (UVA‐BL) as a post‐treatment step for the degradation of the residual COD and color in winery wastewater (WiWW) after biological treatment.RESULTSThe effect of WiWW dilution (0, 50%), TiO2 concentration (0–1000 mg/L), catalyst type (TiO2, ZnO), pH (3, 6, 8.4), H2O2 addition (0–1000 mg/L), and treatment time on process efficiency was evaluated. At the best‐assayed conditions (1000 mg/L TiO2, 1000 mg/L H2O2), COD removal percentages in the range of 94–97% were obtained and color was removed by 99% within 180 min of treatment under all irradiation sources. The process was enhanced when the WiWW was subjected to 50% dilution and its pH was adjusted to 6. Among the three irradiation sources, UVA‐BL led to a marginally higher photocatalytic performance than solar and UVA‐LED, both of which achieved similar removal efficiencies. Regarding energy efficiency, UVA‐LED was found to be up to 1.7 times more energy efficient than UVA‐BL/TiO2. Finally, in most cases, the phytotoxicity of secondary effluent was eliminated during solar photocatalytic treatment.CONCLUSIONAlteration of basic operating parameters significantly improved process efficiency. In all cases, LED‐driven photocatalysis combined high removal performance and energy efficiency, proving to be an appropriate and sustainable alternative to solar photocatalysis for 24 h operation or for supplementary application during the harvest, when the majority of WiWW is generated. © 2022 Society of Chemical Industry (SCI).

Enhanced photocatalytic degradation property of surfactant-free cobalt oxide nanocapsules on methylene blue dye

The transition metal oxides are emerging materials in solving existing environmental problems of removal of organic dye from the industrial wastes. Out of many transition metal oxides, cobalt oxide is one such potential material of low cost, easy to synthesis, eco-friendly and easily separable from mixtures due to its magnetic property. Herein a facile surfactant-free synthesis route has been adopted for the preparation of Co3O4 nanocapsules (Co 600) which exhibited a better photocatalytic degradation activity. The structure, morphology and optical behaviours were studied by using X-ray diffraction (XRD), scanning electron microscope (SEM), ultraviolet-visible spectroscopy (UV–vis) analyses respectively and vibration modes of Co 600 were studied using Raman analysis. The photocatalytic degradation studies of Co 600 on methylene blue (MB) were carried out under ultraviolet (UV) light irradiation. The examined results showed that the Co 600 exhibited narrow band gap of about 1.65 eV which has better photocatalytic degradation activity on MB with degradation efficiency of about 99% in 90 minute with a rate constant of about 0.064. This might be attributed due to enhanced charge separation, charge transfer and the creation of OH– and O2– radicals under UV irradiation. In addition, the samples were easily recovered from the dye solution using an external magnetic field.

Ionic Ir(III) complex-interfacial layer for efficient carrier collection via induced electric dipole.

The power conversion efficiency (PCE) of polymer solar cells (PSCs) has recently reached >19% through the development of photoactive materials, particularly non-fullerene acceptors. Interfacial layers (ILs) have been another essential factor in optimizing device charge extraction. In this study, we propose a series of ILs, in which ionic iridium(III) (Ir(III)) complexes of different alkali metal cations (Li+, Na+, and K+) enhance the charge collection efficiency between zinc oxide and active layers through an induced internal electric field. The anionic coordinate sphere and counter-cations of the Ir(III) complexes are distributed according to the operating voltage of the PSCs, causing electric dipoles that enhance the internal electric field and charge collection efficiency. Ion species migration in the ILs is confirmed using electrochemical impedance spectroscopy. The PCE of the PM6:Y6-based PSCs was improved from 14.0% to 15.6% by introducing an IL (Ir-K+). Furthermore, the stability of PSCs containing ionic Ir(III) complexes is enhanced significantly under ultraviolet (UV) light and AM 1.5 G one-sun irradiation owing to the intense UV absorption capacity and photo durability of the ILs. A device containing the Ir(III) complex-based ILs retained ∼60% of its initial PCE after UV irradiation, whereas the control device retained only ∼20%.

Investigation of the luminescence properties and energy transfer mechanisms in Gd3TaO7:Bi3+,Eu3+ phosphors for their potential application in full-spectrum WLEDs.

In recent years, there has been increasing effort devoted to the development of single-phase white phosphors due to drawbacks such as severe reabsorption and color deviation in traditional white light-emitting diodes (WLEDs). A new feasible strategy has emerged for achieving white light emission through the Bi3+-Eu3+ energy transfer in suitable single-phase phosphors. Therefore, a series of Gd3TaO7:xBi3+ and Gd3TaO7:0.01Bi3+,yEu3+ phosphors were synthesized via a high-temperature solid-state method, and their properties were systematically characterized. In Gd3TaO7, Bi3+ occupies two kinds of Gd3+ site, resulting in two broad emission bands peaking at 427 nm and 500 nm respectively under ultraviolet (UV) excitation, which arise from 3P1 → 1S0 transitions. By adjusting the concentration of Eu3+ in Gd3TaO7:0.01Bi3+,yEu3+, effective energy transfer can occur between Bi3+ and Eu3+, thus enabling the regulation of green-white-red luminescence under 332 nm excitation and blue-white-red luminescence under 365 nm UV light irradiation. Upon stimulation with a 365 nm UV chip, Gd3TaO7:0.01Bi3+,0.02Eu3+ emits white light with CIE coordinates of (0.3509, 0.3202), a color temperature of 4629 K, and an impressive color rendering index of 87.96. The above results indicate the potential of Gd3TaO7:0.01Bi3+,yEu3+ phosphor as a viable candidate for WLED applications.

STUDY THE SELF-CLEANING ABILITY OF ZNO CONTAINED COTTON FABRICS

In this study, ZnO nanoparticles were successfully synthesized by the precipitation method, then immobilized onto cotton fabric. The metal oxide nanoparticle-contained fabric exhibits a self-cleaning effect under ultraviolet (UV) illumination. The nanostructure of the prepared samples was detected using Scanning Electron Microscopy (SEM) analysis. The chemical composition changes of the fabrics before and after the modification were detected using The Fourier transform infrared (FT-IR) and Energy Dispersive X-ray Spectroscopy (EDS). After modification with ZnO nanoparticles, the cotton fabric exerted adsorption and decomposition properties again various chemical compounds. Stains of methylene blue (MB), and methylene orange (MO) were introduced into cotton fabric, under UV light, the dyes were faded and ultimately discolored. The degradation of pigments in the solution happened faster and was expressed by the concentration of dyes decreasing over time through UV-vis measurement results. The self-cleaning ability for MB and MO stained cotton fabrics is evaluated quantitatively over time through the K/S value, which showed a good self-cleaning effect.

Fluorescence intensity coded DNA frameworks based on the FRET effect enable multiplexed miRNA imaging in living cells.

miRNA analysis has played an important role in precise diagnosis, treatment and prognosis of cancer, especially multiplexed miRNA imaging. In this work, a novel fluorescence emission intensity (FEI) encoding strategy was developed based on a tetrahedron DNA framework (TDF) carrier and the FRET effect between Cy3 and Cy5. Six FEI-encoded TDF (FEI-TDF) samples were constructed by tuning the labeling number of Cy3 and Cy5 at the vertexes of the TDF. For fluorescence characterization in vitro, distinct FEIs in the spectra and different colors under ultraviolet (UV) irradiation of FEI-TDF samples were observed. By dividing the ranges of FEIs of samples, the stability of FEIs was highly improved. Based on the ranges of FEIs in each sample, five codes with good discrimination were finally developed. Before the application of intracellular imaging, the excellent biocompatibility of the TDF carrier was proved by CCK-8 assay. The barcode probes based on samples 12, 21 and 11 were designed as example models to realize multiplexed imaging of miRNA-16, miRNA-21 and miRNA-10b in MCF-7 cells with obviously different fluorescence merged colors. FEI-TDFs provide a new research perspective for the development of fluorescence multiplexing strategies in the future.

Фотолиз сульфагуанидина в воде

The phototransformation of sulfaguanidine in water under ultraviolet (UV) radiation was studied experimentally and theoretically. Absorption, fluorescence and fluorescence excitation spectra of the studied substance before and after irradiation were obtained. Under the influence of KrCl excylamp radiation, stained photoproducts were formed. Quantum-chemical analysis of the orbital nature and localization of electronic transitions of complexes of photoproducts with water 1 : 3 reveals great similarity with the spectrum of the complex of the parent compound. The energy of electronic transitions of primary photoproducts decreases that is there is a low-energy shift of transitions S0→S1(ππ) and S0→S3(ππ) of the original molecule to long-wave region of spectrum (260-315 nm) and decrease of intensity of transition S0→S3(ππ) of sulfaguanidine coplex. In the process of irradiation under the action of KrCl excylamp, the transformation of sulfaguanidine, its primary photoproducts and their subsequent interaction with each other and the solvent occur, which leads to the appearance of a colored photoproduct absorbing at λmax = 560 nm.

Synthesis optimization of ZrO2 nanostructures for photocatalytic applications.

This study aims to optimize the synthesis of semiconductor zirconia (ZrO2) nanoparticles for future photocatalytic applications in degradation of pollutants in wastewater under ultraviolet (UV) light. The synthesis procedure of ZrO2 nanoparticles was optimized by examining the effects of synthesis methods (ultrasound-assisted, hydrothermal method in an autoclave and conventional precipitation), reaction time (2, 6, 10, and 18 h), ambient pH (3, 7, 10, 13), and surfactant type (anionic, cationic, and non-ionic), on the particle size and crystal phase of the nanomaterial. The characterization of the synthesized samples was performed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), high-contrast transmission electron microscopy (HR-TEM), and transmission electron microscope (TEM) analysis. Consequently, to synthesize ZrO2 nanoparticles with the smallest particle size and monoclinic/tetragonal phase, the experimental conditions were optimized as ultrasound-assisted synthesis method, pH 10, and 6 h reaction time without surfactant. Moreover, percentage yield, particle size, crystallinity, monoclinic and tetragonal volumes of ZrO2 nanostructures synthesized under optimized conditions were determined as 39.40%, approximately 9 nm, 46.77, 79%, and 21%, respectively. It has been determined that the particle sizes can be kept under control by controlling the phase composition of ZrO2 nanostructures by optimizing the synthesis parameters. Structural and morphological characterization results can be correlated to the photocatalytic application, showing the potential of this material for the photodegradation of organic dye pollutants.

Photoresponsive reversible self-assembly of rod-coil amphiphiles containing spiropyran groups.

Stimuli-responsive assembly deformation is a key feature in constructing smart soft materials, which makes them versatile and autonomous. In this study, rod-coil amphiphilic compounds containing spiropyran (SP) groups were developed and synthesized to investigate their stimuli-responsive assembly in a solution system with 99% water content. In addition to photochromic phenomena, reversible light-mediated morphological alterations occurred in these molecular aggregates. Based on the different flexible chain segments of rod-coil amphiphiles, the initial assemblies underwent a dissociation-reassembly process under ultraviolet (UV) irradiation, whereupon they deformed or disassembled to assemblies. Furthermore, as the UV source was removed, the original nanostructures were gradually recovered again via the ring-closing reaction process. These compounds, interestingly, can selectively combine with copper ions to produce cross-linked co-assembled nanostructures. The copper ion complex solution of rod-coil amphiphilic compounds emitted unique bright blue fluorescence, which allowed for the specific visual identification of copper ions in aqueous solutions.