Ultraviolet Absorption Spectra Research Articles

Effects of Fe3+-doping and nano-TiO2/WO3 decoration on the ultraviolet absorption and gas-sensing properties of ZnSnO3 solid particles

Zn1-xFexSnO3+x/2 samples (ZFxSO), composed of quasi-spherical solid particles, were synthesized after the calcination of Zn1-xFexSn(OH)6+x and then decorated by nano-TiO2/WO3. The ethanol sensitive performance of pure ZnSnO3 sample can be enhanced by Fe3+-doping at high temperature. The ZF0.1SO sample (i.e., x = 0.1) exhibits highest gas sensing response to ethanol among the ZFxSO samples at 500 ppm, obtaining a maximum response (Rmax) of 260.8 at 260 °C. Although Fe3+-doping can increase the oxygen vacancies in pure ZnSnO3 sample, it can not significantly change the ultraviolet absorption spectrum of the sample due to its strong electronegativity. However, nano-TiO2/WO3 decoration can broaden the ultraviolet absorption spectrum of ZF0.1SO sample and improve its absorption intensity. Under 385 nm UV illumination, the operating temperature (OT) of ZF0.1SO sensor can be reduced by nano-TiO2 decoration, with a Rmax of 198.7 at 110 °C. Moreover, the OT of the ZF0.1SO sensor can be further reduced by the co-decoration of nano-TiO2 and WO3, with a Rmax of 219.5 at 100 °C under the same testing conditions. Possible reasons on the role of Fe3+-doping and nano-TiO2/WO3 decoration were discussed from material structure.

Chemical analysis of nitro‐aromatic compounds of secondary organic aerosol formed from photooxidation of p‐xylene with NOx

AbstractNitro‐aromatic compounds (NACs) measured in ambient aerosol are important contributors to brown carbon. Aromatic compounds are expected to be vital precursors of NACs in the presence of NOx in urban atmospheres. NACs of secondary organic aerosol (SOA) formed from photooxidation of p‐xylene with a variety of NO2 in smog chamber were investigated in this study. NACs were on‐line measured by aerosol laser time‐of‐flight mass spectrometer and verified by off‐line of ultraviolet absorption and electrospray ionization mass spectra. The results show that NO2 can promote the formation of p‐xylene SOA. Different from the carbonyls detected in p‐xylene SOA without NO2, nitrophenols, nitrocatechols, and other NACs via the nitration of phenolic products of p‐xylene are detected as the major components of SOA with NO2. The increase of electrophilic nitro groups in SOA strengthens absorption ability. The mass absorption coefficient averaged over 200–600 nm (<MAC>) of SOA gradually increased with the increasing of the concentration of NO2. The <MAC> of SOA with 1,000 ppb NO2 was comparable to that of biomass burning organic aerosols. These provided experimental basis for studying the formation mechanism and optics of anthropogenic NACs in the background of high concentration of NOx in Chinese urban atmosphere.

Efficient photocatalytic degradation of hazardous pollutants by homemade kitchen blender novel technique via 2D-material of few-layer MXene nanosheets

To attain elevated class MXene (Ti3C2Tx) through a homemade kitchen blender method, high shear mechanical exfoliation is highly required for the efficient delimitations of MXene nanosheets from bulk MAX (Ti3AlC2). We examine large-scale industrial productions of the MXene nanosheets, where combing the predicted 2D materials using a blender is a first-time novel approach with the delaminating solvent as a dimethyl sulfoxide (DMSO). And also manually created layered MXene systems (handmade) delaminating MXene sheets (MX-H) was furthermore employed for environmental dye-degradations applications. The materials characterizations was done for both the bulk MAX, MX-H and the MX-B. Additionally, the surface morphological studies like scanning electron microscopy (SEM) were investigated for both MX-H and MX-B as-prepared samples. SEM images indicated the high shear blander technique formations highly expanded/delaminated MXene (Ti3C2Tx) nanosheets compared to MX-H samples. FTIR technique is employed to identify –OH, C–H, C–O stretching vibrations for both materials. Raman spectroscopy analysis of MX-H and MX-B revealed 484.80 cm−1 Raman shift assigned to E1g phonon mode of (Ti, C, O). The ultraviolet UV visible absorption spectra explored pure and catalyst added Methylene Blue (MB) dye stock solution using annular type photoreactor with visible light source of 300 W. The comparatives of MAX, MX-H and MX-B samples was investigated as photocatalytic activity, The blender made (MX-B) sample revealed 98% of efficiency.

Determination and application of the excited‐state substituent constants of pyridyl and substituted phenyl groups

AbstractThirty six 1‐pyridyl‐2‐arylethenes XCH=CHArY (abbreviated XAEY) were synthesized, in which, X is 2‐pyridyl, 3‐pyridyl and 4‐pyridyl and Y is OMe, Me, H, Br, Cl, F, CF3, and CN. Their ultraviolet absorption spectra were measured in anhydrous ethanol, and their wavelengths of absorption maximum λmax were recorded. Also, the 234 λmax values of 1‐substituted phenyl‐2‐arylethylene compounds (XAEY, where X is substituted phenyl) were collected. The excited‐state substituent constants of three pyridyl groups and 23 substituted phenyl groups (total of 26) were obtained by means of curve‐fitting method. Taking the λmax values of 358 samples of bi‐arylethene derivatives as a data set and 126 samples of bi‐aryl Schiff bases (including nine compounds synthesized by this work) as another data set, quantitative correlation analyses were performed by employing the obtained as a parameter, and good results were obtained for the two data sets. The reliability of the obtained values was verified. The results of this paper can provide excited‐state substituent constants for the study and application of optical properties of conjugated organic compounds containing aryl groups.

μ-Calpain oxidation and proteolytic changes on myofibrillar proteins from Coregonus Peled in vitro

The purpose of this study was to investigate the structural properties of μ-calpain induced by hydroxyl radical oxidation and its effect on the degradation of myofibrillar protein (MP) from the dorsal muscles of Coregonus peled. The carbonyl and sulfhydryl content of μ-calpain changed significantly after oxidation. The content of α-helix in the secondary structure decreased from 0.825 to 0.232 and the changes in intrinsic fluorescence and ultraviolet (UV) absorption spectra indicated that oxidation could cause the expansion and aggregation of µ-calpain molecules. Changes in µ-calpain structure could improve the activity of µ-calpain, reaching the highest value at 0.5 mM H2O2. The highest µ-calpain activity facilitate the degradation of unoxidized MP, while the degradation of oxidized MP was facilitated at the 1 mM H2O2. Thus, our results provide a scientific basis for the interaction mechanism among hydroxyl radical oxidation, µ-calpain, and MP degradation.

Effect of pH and xanthan gum on emulsifying property of ovalbumin stabilized oil-in water emulsions

The poor emulsifying property of Ovalbumin (OVA) greatly restricted the overall development of eggs in the food industries. In this paper, we investigated the effects of different xanthan gum (XG) concentrations and different pH value on OVA-stabilized oil-in-water emulsions. From the results of turbidity, ultraviolet absorption spectra and fluorescence spectra, we could find that OVA and XG had an obvious interaction. With increasing XG concentration (0–0.4%), the particle size of OVA-XG complex-stabilized emulsions gradually decreased and absolute value of zeta potential significantly increased. The storage stability of the emulsions was obviously improved by increasing the amount of XG. The apparent viscosity of complex-stabilized emulsions significantly increased, thereby improving the emulsions stability. In addition, our results confirmed emulsions stability largely depended on the pH value. OVA-XG composite emulsion showed a better stability at pH 5.5. Our findings indicated that XG had the potential as an emulsions stabilizer and could be used in egg white-derived foods.

Bronchial granulocytes in the development of epithelial destruction and oxidative lipid modification in patients with bronchial asthma with cold and osmotic airway hyperresponsiveness

Free radical damage to the respiratory tract in patients with asthma leads to the destruction of the bronchial parenchyma and the generation of signaling molecules of inflammation by parenchymal cells. Objective: to study the role of the structural and functional status of granulocytes in the development of epithelial destruction and oxidative lipid modification in the bronchi of asthma patients with airway hyperresponsiveness to cold and hyperosmolar stimuli. Material and methods. In 48 asthma patients, the level of asthma control was assessed according to the Asthma Control Test (ACT) questionnaire; lung function; bronchial response to 3-minute isocapnic hyperventilation with cold (- 20 °C) air (IHCA) and with ultrasonic inhalation of hypertonic (4.5 %) NaCl solution (IHS). The cellular composition and the degree of cellular destruction in induced sputum (IS) were measured. Reaction products for enzymes from the group of heme-containing peroxidases (myeloperoxidase in neutrophils, peroxidase in eosinophils) with the calculation of the average cytochemical coefficient were studied. The content of lipid peroxidation products in according to ultraviolet absorption spectra of lipid extracts in exhaled breath condensate (EBC) was assessed. Results. Patients of group 1 (n=15) with airway hyperresponsiveness to IHCA and IHS in relation to group 2 (n=33) with a negative reaction had lower ACT (14.7±1.4 vs. 18.4±0.8 points, p=0.017). In sputum, the number of neutrophils in groups 1 and 2 was 41.8±6.4 vs. 33.6±3.4 %, eosinophils – 23.5±3.5 vs. 14.9±2.6 %; average cytochemical coefficient of peroxidase 117.5±12.5 vs. 88.8±8.9 pixels (p=0.07), cell destruction index (CDI) of bronchial epithelium 0.56±0.04 vs. 0.39±0.02 r.u. (p =0.0002). The content of diene conjugates (E233) in EBC in group 1 was higher than in group 2 (0.07±0.008 vs. 0.05±0.005 optical units, p˂0.05). A correlation was found between peroxidase level and CDI, the number of totally destroyed cells (IV class of cell destruction), between the number of neutrophils in IS and E233, as well as the ratio of E233 to E206 (non-oxidized lipids) in EBC. Conclusion. In asthma patients with airway hyperresponsiveness to cold and hyperosmolar stimuli, changes in the structure of the epithelium and the structural and functional profile of granulocytes are associated with the activation of the peroxidase function of granulocytes and are interrelated with lipid peroxidation.

A comparative study on the extraction effects of common agents on collagen-based binders in mural paintings

In this paper, a comparative study was conducted on the extraction effects of six agents for collagen-based mural painting binders. These agents were used to extract the residual proteins in the non-aged and thermal aged samples. The protein extraction efficiencies of different extracting agents were quantitatively determined by bicinchoninic acid (BCA) method, and then processed by multivariate analysis of variance (MANOVA). The impact of the extraction process on the protein structure was characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), ultraviolet absorption spectrum (UV) and circular dichroism (CD). The results showed that, for both non-aged and aged samples, the extraction efficiency of 2 M guanidine hydrochloride (GuHCl) was significantly higher than the other five agents, with less damage to the protein structure during the extraction process.

Thioureas Bridged Polysiloxanes for Ultrafast Detection of Cr6+ and Applications

AbstractPolythiourea, as a kind of seductive material, has been widely applied in various fields. However, the design strategy of polythiourea remains a strong challenge mainly owing to synthesis process is cumbersome and noble metals participate in the reaction. In this report, a new synthetic method is presented to construct poly (siloxane‐thioureas) (PTUs) via a simple and economic “one‐pot” method. The optical properties of PTUs are mainly investigated by the ultraviolet absorption spectrum and fluorescence spectrum. Noteworthly, PTUs display ultrafast response rate to Cr6+. In addition, PTUs also possess excellent photostability and biocompatibility. A paper sensor based on PTUs is also prepared by visual fluorescence change to achieve the purpose of detection of Cr6+. Herein, it is desired that, as a new type of polythiourea material, PTUs could extend the applications in the bioimaging field.

Inhibition of in vitro enzymatic starch digestion by coffee extract

There is evidence that moderate coffee consumption is beneficial in the prevention of type 2 diabetes, however, the underlying mechanism is not understood. In this study, the effects of an extract of ground coffee on the in vitro enzymatic digestion of starch were investigated. The coffee extract decreased the rate and extent of starch digestion, with kinetic analysis showing that the extract reduced the binding affinity of the enzymes for the substrate and their catalytic turnover. Fluorescence quenching indicated that the coffee extract formed complexes with the digestive enzymes through a static quenching mechanism. Ultraviolet absorption and circular dichroism spectra of the digestive enzymes confirmed that the coffee extract decreased the proportion of β-sheet structures in the enzymes. Therefore, we conclude that compounds in the soluble coffee extract can interact with porcine pancreatic amylase and amyloglucosidase causing inhibition of the enzymes and decreasing in vitro starch digestion.

Impact of biosynthesized silver nanoparticles cytotoxicity on dental pulp of albino rats (histological and immunohistochemical study)

This study aimed to evaluate the potential cytotoxic effect of oral administration of silver nanoparticles (Ag-NPs) on adult albino rats’ pulp tissue; due to the enormous uses of Ag-NPs in the medical and dental field. The Ag-NPs were synthesized via the green process using peels of pomegranate extract. The pomegranate-mediated Ag-NPs were subjected to morphological and spectral analysis through ultraviolet visible absorption spectra, transmission electron microscopy, Fourier transforms infrared, Zeta-potential measurements, and energy dispersive X-ray spectroscopy. The structural and morphological characterization techniques confirmed the proper synthesis of biosynthesized Ag-NPs with a size around 20 ​nm and the surface plasmon resonance peak within 400–450 ​nm. The oral cytotoxic effect of Ag-NPs was assessed through detecting the histological (hematoxylin & eosin, Masson’s trichrome) and immunohistochemical (vascular endothelial growth factor (VEGF), Caspase-3 proteins) variations. The data was analyzed statistically through using the SPSS software. Dental pulp tissues of albino rats-treated with Ag-NPs revealed that most of the odontoblasts with marked hydropic degeneration, vacuolization of their cytoplasm, loss of organization and apoptosis. Marked vasodilatation and cognition of blood vessels were detected. There was weak to moderate positive reactivity to Masson’s trichrome stain. There was statistically significant decrease in the expression of VEGF in the treated group and highly statistically significant increase in the expression of Caspase-3 in comparison with the control group. ConclusionOral administration of Ag-NPs induced size and dose-dependent structural changes in the pulp tissue of adult male albino rats.

Enhanced energy storage properties achieved in Na0.5Bi0.5TiO3-based ceramics via composition design and domain engineering

Dielectric ceramic materials with high power density and fast charge–discharge speed have attracted increasing attention in recent years. However, their mutually restricted energy density and efficiency as well as unsatisfactory temperature stability have been the main obstacles for their practical applications. Herein, a high recoverable energy density of 5.02 J·cm−3 and a high efficiency of ~ 90% can be obtained under 422 kV·cm−1 in the Sr0.85Sm0.1TiO3 (SST)-modified Na0.5Bi0.5TiO3 (NBT) ceramics via composition design and domain engineering strategy, and the excellent stability of energy storage properties in frequency (1–100 Hz) and temperature (20–180 °C) were also observed at 250 kV·cm−1 in the 0.50NBT-0.50SST ceramics, which are attributed to the improved breakdown strength (Eb) and the enhanced relaxation behavior. The increased band gap width and refined grain size are responsible for the significantly enhanced Eb of Na0.5Bi0.5TiO3-based solid solution, being confirmed by ultraviolet and visible (UV–vis) absorption spectra as well as scanning electron microscopy. The generation of polar nanoregions as demonstrated by piezoresponse force microscopy and transmission electron microscopy results in a negligible remanent polarization and thermally stable polarization-field response. It is worth noting that the energy density will be further greatly optimized due to the improvement of Eb if this ceramic composite is made into multilayer ceramic capacitor as a dielectric layer. Moreover, a large power density of 188.6 MW·cm−3 and a fast discharge speed of 70 ns can also be achieved in the optimized composition. The results show that the multi-scale optimization strategy is an effective way to realize excellent comprehensive energy storage performances in the Na0.5Bi0.5TiO3 based ceramics.

Study on Chromaticity Removal from Mineral Processing Wastewater with Salicylic Hydroxamic Acid by Granular Activated Carbon Catalyzed Ozonation

Salicylic hydroxamic acid is a novel flotation reagent used in mineral processing. However, it impacts the flotation wastewater leaving behind high chromaticity which limits its reuse and affects discharge for mining enterprises. This study researched ozonation catalyzed by the granular activated carbon (GAC) method to treat the chromaticity of the simulated mineral processing wastewater with salicylic hydroxamic acid. The effects of pH value, ozone (O3) concentration, GAC dosage, and reaction time on chromaticity and chemical oxygen demand (CODCr) removal were discussed. The results of individual ozonation experiments showed that the chromaticity removal ratio reached 79% and the effluent chromaticity exceeded the requirement of reuse and discharge when the optimal experimental conditions were pH value 3, ozone concentration 6 mg/L, and reaction time 40 min. The orthogonal experimental results of catalytic ozonation with GAC on chromaticity removal explained that the chromaticity removal ratio could reach 96.36% and the chromaticity of effluent was only 20 when the optimal level of experimental parameters was pH value 2.87, O3 concentration 6 mg/L, GAC dosage 0.06 g/L, reaction time 60 min respectively. The degradation pathway of salicylic hydroxamic acid by ozonation was also considered based on an analysis with ultraviolet absorption spectrum and high-performance liquid chromatography (HPLC).

Mapping time-dependent quasi-energies of laser dressed helium.

Extreme ultraviolet (EUV) transient absorption spectrum of helium dressed by a moderately intense infrared laser pulse is investigated. Strategies for correct retrieval of the time-dependent quasi-energies of helium with excitation energies covering both singly and doubly excited states are proposed. For long-lived singly excited states, the profound hyperbolic structures due to long lasting dipole can be diminished by convoluting the transient absorption spectrogram with a spectral window, allowing the time-dependent quasi-energies close to 1s2p resonance to be correctly mapped out. For short-lived doubly excited states near 2s2p resonance, the radiation dipole decays rapidly due to autoionization and the transient absorption spectrogram already recovers the main structure of quasi-energies without the convolution operation. The quantum simulation indicates that the convolution operation controls the effective decay speed of the dipole moment, which effectively builds up an instant probe that is essential for mapping time dependent quasi-energies of laser dressed systems.

Methods, principles and applications of optical detection of metal ios

• The optical detection methods of 12 common metal ions are reviewed. • The main principles and experimental phenomena of optical detection are summarized. • The development and advantages of optical detection methods are summarized. • The applications of optical detection method are summarized. • The future development and main challenges of optical detection are discussed. Heavy metal elements were widely used in alloy manufacturing, medical treatment, food additive, military industry and other fields, which were harmful to human body. Optical detection was a non-contact nondestructive detection method, which had the advantages of high selectivity, high sensitivity and low cost, and had important applications and prospects in environmental monitoring and biological science. In this paper, the optical detection methods, detection principles and detection methods of 12 kinds of metal ions (Ag + , Al 3+ , Cd 2+ , Co 2+ , Cr 3+ , Cu 2+ , Fe 2+ , Fe 3+ ,Hg 2+ ,Pb 2+ , Pd 2+ ,Zn 2+ ) were reviewed. Fluorescence, colorimetry and spectral change were the main detection methods. Fluorescence detection methods mainly included fluorescence quenching, fluorescence enhancement and fluorescence spectrum changes; The colorimetric method included the change of color and the change of ultraviolet absorption spectrum; The spectral changes mainly included circular dichroism, phosphorescence and surface enhanced Raman scattering, etc. Photoinduced electron transfer, intramolecular charge transfer and fluorescence resonance energy transfer were the primary principles of optical detection. The application prospect and main challenges of optical detection were discussed.

Programmable Engineering of DNA-AuNP Encoders Integrated Multimodal Coupled Analysis for Precision Discrimination of Multiple Metal Ions.

A cross-responsive strategy (CRS) based on gold nanoparticles (AuNPs) through attaching various recognition receptors on the surface of AuNPs for identifying multiple analytes is presented, and the detection throughput and overall identification accuracy are improved. However, the CRS's recognition receptor cannot get comprehensive information from the target analytes limited in number and type, which determines the overall identification accuracy. Therefore, the practicability of the CRS runs into a bottleneck. Herein, we report a programmable DNA-AuNP encoder combined with a multimodal coupled analysis algorithm for high-throughput detection and accurate analysis of multiple metal ions. The programmable DNA-AuNP encoder breaks through the limitation of the recognition receptor's quantity. Furthermore, the multimodal signals from target metal ion-induced DNA-AuNP aggregation are related to and observed in the ultraviolet absorbance spectrum, surface potential, and particle diameter. The multimodal coupled analysis algorithm can reflect comprehensive information on the target analyte more completely. Finally, this study provides a highly generic tool for the cross-responsive strategy.

A high-voltage rechargeable alkaline Zn–MnO4− battery with enhanced stability achieved by highly reversible MnO4−/MnO42− redox pair

Development of rechargeable alkaline Zn–Mn batteries has been facing big challenges for low working voltage and poor cycling stability, although they have advantages of low cost, high safety, and simple maintenance. For the first time, this work demonstrates a record high voltage (1.78 V) for rechargeable alkaline Zn–MnO4− battery achieved by a high reversible redox pair of MnO4−/MnO42−, which shows excellent cycling stability up to 1,500 cycles at a high current density of 20 mA cm−2 without obvious capacity attenuation. The MnO4−/MnO42− redox reaction investigated by ex-situ scanning electron microscope as well as ultraviolet and visible absorption spectrum indicates high reversibility of the MnO4−/MnO42− redox couple after the activation during the first discharge process. Furthermore, benefiting from the liquid-phase reaction nature of MnO4−/MnO42−, a flow battery is further prototyped to show highly stable cycles with 95.8% of discharge capacity retention for 600 cycles at the current density of 40 mA cm−2.

Electrochemical detection of nitrate ions via reduction of NO2−and oxidation of NO reactions based on Cu@TiO2 coreshell/nafion/polyalizarin immobilized electrode

In this paper, we synthesized Cu nanoparticles and Cu@TiO2 core–shell. Regarding the characterization of the Cu nanoparticles and Cu2O@C core–shell, the transmission electron microscopy (TEM), ultraviolet (UV) absorption spectrum, dynamic light scattering (DLS) and zeta potential techniques were employed. The Cu@ TiO2 core–shell with conductive polymers such as Nafion (Nf) and Polyalizarin yellowe R (PAR) immobilizing on glassy carbon electrode (Cu@TiO2-Nf/PAR/GCE). This was used for fabrication of an original electrochemical sensor to measurement nitrate via reduction of NO2− and oxidation of NO reactions. Cyclic voltammetry and impedimetric techniques were employed to confirm the novel sensor construction. Other electrochemical analysis was done by cyclic voltammetry and differential pulse voltammetry methods. The results shed lights on the matter that, Cu@TiO2-Nf/PAR/GCE composite has a great electrocatalytic effect for detecting and determining nitrate ion at −0.8V(Red2) and 0.9V(OX). Linear range, sensitivity and limit of detection were calculated for two area potentials.

A new synthetic route for the production of a thiophene-based methine-bridged type conjugated polymer

Methine-bridged type π-conjugated polymer was synthesized using a Migita–Kosugi–Stille polycondensation reaction in the presence of a Pd(0) catalyst followed by oxidation with 2,3-dichloro-5,6-dicyano-p-benzoquinone. The chemical structure of the obtained polymer was confirmed by infrared absorption spectroscopy. The optical properties of the polymer were confirmed by ultraviolet visible optical absorption and photoluminescence spectra. Vapor phase iodine doping was performed to generate a charge carrier in the polymer. The magnetic properties of the carrier were examined by electron spin resonance (ESR). The doped polymer exhibited Pauli’s para-magnetism with constant ESR linewidths and g-values, whereas the ESR intensity increased with decrease in temperature. This indicated the formation of charge carriers on the backbone of the polymer by iodine doping, which is typical behavior of polarons in conductive polymers. The present study describes the first synthesis of a methane-bridged π-conjugated polymer using a Migita–Kosugi–Stille type polycondensation.

Effects of Hydrothermal Temperature on the Photocatalytic Degradation Performance of Bismuth Oxide Formate

The effects of hydrothermal temperature on the photocatalytic degradation performance of bismuth oxide formate were investigated using Bi(NO3)3·5H2O and N, N-dimethylformamide prepared by a simple hydrothermal process. Its structure and properties were analyzed by field emission scanning electron microscope, Fourier transform infrared spectroscopy, x-ray powder diffraction, and ultraviolet and visible absorption spectra. The photocatalytic degradation performance was evaluated in tetracycline solutions. Temperature has a great influence on the morphology of BiOCOOH, and reduces the width of the energy gap. The photocatalytic degradation rate of BiOCOOH prepared at 160°C (BiO-160) with regard to tetracycline was 3.2 times that at 140°C. Within 70 min, BiO-160 can almost completely degrade 10 mg/L of tetracycline in aqueous solution. Photocatalytic mechanisms showed that ·OH plays a major role, while ·O2− plays a secondary role in the photocatalytic degradation of tetracycline by BiO-160.