Increasing Surface UV Radiation in the Tropics and Northern Mid-Latitudes due to Ozone Depletion after 2010

Excessive exposure to ultraviolet(UV)radiation harms humans and ecosystems.The level of surface UV radiation had increased due to declines in stratospheric ozone in the late 1970s in response to emissions of chlorofluorocarbons.Following the implementation of the Montreal Protocol,the stratospheric loading of chlorine/bromine peaked in the late 1990s and then decreased;subsequently,stratospheric ozone and surface UV radiation would be expected to recover and decrease,respectively.Here,we show,based on multiple data sources,that the May–September surface UV radiation in the tropics and Northern Hemisphere mid-latitudes has undergone a statistically significant increasing trend[about 60.0 J m^(–2)(10 yr)^(–1)]at the 2σlevel for the period 2010–20,due to the onset of total column ozone(TCO)depletion[about−3.5 DU(10 yr)^(–1)].Further analysis shows that the declines in stratospheric ozone after 2010 could be related to an increase in stratospheric nitrogen oxides due to increasing emissions of the source gas nitrous oxide(N_(2)O).

Enhanced electrochemical oxidation of phenol by introducing ferric ions and UV radiation

The mineralization of phenol in aerated electrochemical oxidation has been investigated.The results show that a cathodic Fenton process can occur when the Ti-0.3Mo-0.8Ni alloy material is used as cathode in solution containing ferric or ferrous ions; moreover,the reinforcement of cathodic Fenton process on the total organic carbon (TOC) removal rate of phenol is quite distinct.Among the metallic ions investigated,the ferric ion is the best catalyst for the electrochemical mineralization of phenol at initial...

Oxidative Degradation of Thermoplastic Starch Induced by UV Radiation

Among biopolymers,thermoplastic starch(TPS)is a good candidate to obtain biomaterials because of its natural origin,biodegradable character,and processability.Exposure to ultraviolet(UV)radiation causes significant degradation of starch-based materials,inducing photooxidative reactions which result in breaking of polymer chains,production of free radical,and reduction of molar mass.These changes produce a deterioration of TPS mechanical properties,leading to useless materials after an unpredictable time.In this work,changes induced on TPS by UV radiation,analyzing structural properties and mechanical behavior,are studied.TPS was obtained through thermo-mechanical processing of native corn starch in the presence of water(45%w/w)and glycerol(30%w/w)as plasticizers.Films were obtained by thermocompression and,before testing,specimens were conditioned to reduce material fragility.Photodegradation process was performed by exposing TPS to 264 h UV radiation in a weathering test chamber.Specimen’s weight loss was determined gravimetrically.Chemical changes were studied by Fourier Transform Infrared Spectroscopy(FTIR)and morphological modifications were analyzed by Scanning Electron Microscopy(SEM).Reduction of weight average molar mass was measured by Static Light Scattering(SLS).Changes in mechanical properties were studied from tensile tests.After 96 h exposure,TPS specimens presented a weight reduction of 4-6%,mainly attributed to plasticizers lost by evaporation.SEM observations showed that UV radiation induced morphological changes on TPS,evidenced by an increment of specimens cracking.By FTIR,it was detected the presence of an additional band located at 1726 cm-1 in samples submitted to UV radiation,attributed to the formation of-C=O groups.Weight average molar mass of native starch was in the order of 107 g mol-1.TPS exposure to UV radiation decreased significantly its molar mass,confirming molecular degradation of the biopolymer.When TPS was exposed during 48 h,it was detected a considerable decrease in elongation at break values(~85%),indicating that TPS flexibility was reduced.On the other hand,after 48 h exposure,TPS elastic modulus was 55 times higher than those of the unexposed specimens,evidencing an increase in material rigidity.TPS maximum tensile strength was also increased by UV light,with an increment of^400%after 48 h exposure.Results revealed that starch-based materials can be degraded by exposure to UV radiation,modifying their microstructure and mechanical performance.

Effect of UV Radiation and Other Abiotic Stress Factors on DNA of Different Wild Plant Species Grown in Three Successive Seasons in Alpine and Subalpine Regions

Plants in natural ecosystems are exposed to a combination of UV radiation,ionizing radiation(IR)and other abiotic factors.These factors change with the altitude.We investigated DNA alterations of some wild plants of different plant families in natural ecosystems at three altitudes in Rila Mountain,Bulgaria(1500,1782,and 2925 m above sea level(a.s.l.)exposed to UV radiation,IR and other abiotic stresses,to assess the tolerance of plant species to the changing environmental conditions in three successive growth seasons.For this purpose,physicochemical,cytogenetic,and molecular methods were applied.DNA damage was assessed by micronucleus test and molecular method comet assay adapted and applied by us to wild plant species from Onagraceae,Rosaceae,Boraginaceae,Saxifragaceae,Orobanchaceae,Asteraceae and Poaceae families,growing at three different altitudes.Variability in the DNA sensitivity and the level of tolerance was observed among the plant species in response to combined abiotic factors assessed by induced DNA damage and gross beta activity.The studied representatives of Poaceae were less susceptible than the other studied species at all three altitudes and showed close level of DNA injuries to that of unaffected control plant grown in laboratory conditions.The lower levels of DNA damage of these wild plant species corresponded to their lower ability to accumulate radionuclides.There was a particularly pronounced low level of DNA injuries in the plant species at the highest altitude.The level of DNA damage showed correlation with the values of some abiotic environmental factors.The results would contribute to the elucidation of the extent of adaptation of plant species to the continuously changing environment and would be useful in selecting sensitive herbaceous monitor species for environmental impact assessment at mountain and alpine sites.

Light history modulates growth and photosynthetic responses of a diatom to ocean acidification and UV radiation

To examine the synergetic effects of ocean acidification(OA)and light intensity on the photosynthetic performance of marine diatoms,the marine centric diatom Thalassiosira weissflogii was cultured under ambient low CO_(2)(LC,390μatm)and elevated high CO_(2)(HC,1000μatm)levels under low-light(LL,60μmol m^(-2)s^(-1))or high-light(HL,220μmol m^(-2)s^(-1))conditions for over 20 generations.HL stimulated the growth rate by 128 and 99%but decreased cell size by 9 and 7%under LC and HC conditions,respectively.However,HC did not change the growth rate under LL but decreased it by 9%under HL.LL combined with HC decreased both maximum quantum yield(FV/FM)and effective quantum yield(ΦPSII),measured under either low or high actinic light.When exposed to UV radiation(UVR),LL-grown cells were more prone to UVA exposure,with higher UVA and UVR inducing inhibition ofΦPSII compared with HL-grown cells.Light use efficiency(α)and maximum relative electron transport rate(rETRmax)were inhibited more in the HC-grown cells when UVR(UVA and UVB)was present,particularly under LL.Our results indicate that the growth light history influences the cell growth and photosynthetic responses to OA and UVR.

VAMP726 from maize and Arabidopsis confers pollen resistance to heat and UV radiation by influencing lignin content of sporopollenin

Sporopollenin in the pollen cell wall protects male gametophytes from stresses.Phenylpropanoid derivatives,including guaiacyl(G)lignin units,are known to be structural components of sporopollenin,but the exact composition of sporopollenin remains to be fully resolved.We analyzed the phenylpropanoid derivatives in sporopollenin from maize and Arabidopsis by thioacidolysis coupled with nuclear magnetic resonance(NMR)and gas chromatography–mass spectrometry(GC–MS).The NMR and GC–MS results confirmed the presence of p-hydroxyphenyl(H),G,and syringyl(S)lignin units in sporopollenin from maize and Arabidopsis.Strikingly,H units account for the majority of lignin monomers in sporopollenin from these species.We next performed a genome-wide association study to explore the genetic basis of maize sporopollenin composition and identified a vesicle-associated membrane protein(ZmVAMP726)that is strongly associated with lignin monomer composition of maize sporopollenin.Genetic manipulation of VAMP726 affected not only lignin monomer composition in sporopollenin but also pollen resistance to heat and UV radiation in maize and Arabidopsis,indicating that VAMP726 is functionally conserved in monocot and dicot plants.Our work provides new insight into the lignin monomers that serve as structural components of sporopollenin and characterizes VAMP726,which affects sporopollenin composition and stress resistance in pollen.

The adsorption behavior of metals in aqueous solution by microplastics effected by UV radiation

Microplastics are considered as the carrier to heavy metals in the environment.But the sorption ability of microplastics influenced by photo-aging is remaining unclear.In the present study,the sorption of two kinds of metal ions(Cu^2+ and Zn^2+)in the aqueous solution by both the virgin and aged microplastics was investigated.Polyethylene terephthalate(PET)debris,one of the typical kinds of microplastics was chosen in this study.Photo-aging of microplastics in environment was simulated using UV radiation in the laboratory.Date analysis indicated that the aged microplastics had higher adsorption capacity of heavy metals than original ones.This could be related to the increased surface area and oxygen containing function appeared in the surface of aged microplastics after UV radiation.When prolonging the time of radiation,the enhanced adsorption capacities of microplastics appeared for Cu^2+ and Zn^2+.These results showed a great interaction between the aging degree of plastics and sorption capacity to heavy metals.Meanwhile,external conditions including temperature and pH value were also showed great influence to the adsorption behavior.

Effects of ultraviolet(UV) radiation and litter layer thickness on litter decomposition of two tree species in a semi-arid site of Northeast China

Forests and grasslands in arid and semi-arid regions receive high-intensity ultraviolet（UV） radiation year-round. However, how the UV radiation affects the litter decomposition on the forest floor remains unclear. Here, we conducted a field-based experiment in 2011 in the southeastern Horqin Sandy Land, Northeast China, to investigate the effects of UV radiation, litter layer thickness, and their interaction on the mass loss and chemical properties of decomposing litter from Xiaozhuan poplar（Populus × xiaozhuanica） and Mongolian pine（Pinus sylvestris var. mongolica） plantation trees. We found that UV radiation accelerated the decomposition rates of both the Xiaozhuan poplar litter and Mongolian pine litter. For both species, the thick-layered litter had a lower mass loss than the thin-layered litter. The interaction between UV radiation and litter layer thickness significantly affected the litter mass loss of both tree species. However, the effects of UV radiation on the chemical properties of decomposing litter differed between the two species, which may be attributed to the contrasting initial leaf litter chemical properties and morphology. UV radiation mostly had positive effects on the lignin concentration and lignin/N ratio of Xiaozhuan poplar litter, while it had negative effects on the N concentration of Mongolian pine litter. Moreover, litter layer thickness and its interaction with UV radiation showed mostly positive effects on the N concentration and lignin/N ratio of Xiaozhuan poplar litter and the ratios of C/N and lignin/N of Mongolian pine litter, and mostly negative effects on the C/N ratio of Xiaozhuan poplar litter and the N concentration of Mongolian pine litter. Together, these results reveal the important roles played by UV radiation and litter layer thickness in the process of litter decomposition in this semi-arid region, and highlight how changes in the litter layer thickness can exert strong influences on the photodegradation of litter in tree plantations.

UV RADIATION INDUCED GRAFT COPOLYMERIZATION OF ALLYL ACETATE ONTO POLY(ETHYLENE TEREPHTHALATE)(PET) FILMS FOR FUEL CELL MEMBRANES

Ultraviolet （UV）-induced graft copolymerization of allyl acetate （AA） monomer onto poly（ethylene terephthalate） （PET） films and the subsequent sulfonation on the monomer units in the grafting chain using chlorosulfonic acid （C1SO3H） were carried out to prepare proton exchange membranes （PEMs） for fuel cells. A maximum grafting value of 12.8% was found for 35 vol% allyl acetate after 3 h radiation time. Optimum concentration of C1SO3H was selected for the sulfonation reaction to be 0.05 mol/L based on the degree of sulfonation and the tensile strength studies of the membrane. The degree of sulfonation increased as the sulfonation reaction temperature and sulfonation time were increasing. The radiation grafting and the sulfonation have been confirmed by titrimetric and gravimetric analyses as well as FTIR spectroscopy. The maximum ion exchange capacity （IEC） of 0.04125 mmol g-1 was found at 12.1% degree of sulfonation and the maximum proton conductivity was found to be 0.035 S cm-1 at 30℃ and a relative humidity of 60%. The various physical and chemical properties of the PEMs such as water uptake, mechanical strength, thermal durability and oxidative stability were also studied. To investigate the suitability of the prepared membrane for fuel cell applications, its properties were compared with those ofNafion 117.

Narrowband EUV Sc/Si Multilayer for the Solar Upper Transition Region Imager at 46.5 nm

The transition region is the key region between the lower solar atmosphere and the corona, which has been limitedly understood by human beings. Therefore, the Solar Upper Transition Region Imager(SUTRI) was proposed by Chinese scientists and launched in 2022 July. Right now, the first imaging observation of the upper transition region around 46.5 nm has been carried out by SUTRI. To ensure the spectral and temporal resolution of the SUTRI telescope, we have developed a narrowband Sc/Si multilayer. Based on the extreme ultraviolet(EUV)reflectivity measurements, the multilayer structure has been modified for ensuring the peak position of reflectivity was at 46.5 nm. Finally, the narrowband Sc/Si multilayer was successfully deposited on the hyperboloid primary mirror and secondary mirrors. The deviation of multilayer thickness uniformity was below than 1%, and the average EUV reflectivity at 46.1 nm was 27.8% with a near-normal incident angle of 5°. The calculated bandwidth of the reflectivity curve after primary and secondary mirrors was 2.82 nm, which could ensure the requirements of spectral resolution and reflectivity of SUTRI telescope to achieve its scientific goals.

Effect of UV-B radiation on the feeding behavior of the rotifer Brachionus plicatilis

Effect of UV - B radiation on the feeding behaviour of marine zooplankton is important to assessing the health harm of marine ecosystem due to the gradually enhanced UV - B radiation in air. However, there are a few studies on this topic. The feeding behavior of the rotifer, Brachionus plicatilis, under the treatment of UV - B radiation on five species of microalgae, i. e. , Chlorella sp. , Tetraselmis chuii, Isochrysis galbana Park 8701, Chaetoceros muelleri Lermumerman, and Nitzschia clostertum, was studied. The results showed that the filtering and feeding rates of the rotifer decreased significantly with the dose increase of UV - B radiation when fed with five species of microalgae respectively （ P 〈 0.05 ） which indicates UV - B radiation inhibits the feeding activities of the rotifer on microalage. The mixed culture experiments shows the rotifer preferred to feed Chlorella sp. , then C. muelleri, L galbana, N. clostertum and T. chuii in turn if without UV - B radiation. Under the highest dose of UV - B radiation treatment （2.70 kJ/m^2）, the rotifer preferred to feed C. muelleri, then Chlorella sp. , N. clostertum, L galbana and T. chuii in turn. Chlorella sp. , L galbana and C. muelleri became the more favorite foods of the rotifer while T. chuii and N. clostertum became less favorite foods. The change of feeding rate and feeding selectivity of zooplankton driven by the enhanced UV - B radiation will lead to the change in the structure of phytoplankton community.

Formation of Natural Melanin/TiO_(2) Nanostructure Hybrids with Enhanced Optical,Thermal and Magnetic Properties as a Soft Material

The natural Melanin/TiO_(2) was synthesized by the use of ultrasonication under UV radiation.The influence of natural melanin on the structural,optical and thermal properties of TiO_(2) nanoparticles was investigated by using Fourier transform infrared spectroscopy,thermogravimetric analysis and UV-Vis spectroscopy.It was observed that incorporating natural melanin on TiO_(2) nanoparticles(TiO_(2)-Mel)occurred at 2.01 eV with a low value of Urbach energy around 100 meV indicating improvement in the crystalline structure.Magnetic measurement at room temperature showed diamagnetic behavior.Furthermore,thermal results showed that TiO_(2)-Mel is stable even at temperatures up to 400℃.According to the results obtained by the thermal stability of melanin with titanium dioxide,it can be a good candidate in many applications such as solar cells and optoelectronics.

Degradation of methotrexate by UV/peroxymonosulfate:Kinetics,effect of operational parameters and mechanism

Methotrexate(MTX)is one of the most consumed anti-cancer drugs in the pharmaceutical market around the world.The widespread occurrence of MTX in aquatic environment through hospital effluent has attracted increasing concern due to its potential to induce water pollution.In the present study,the degradation of MTX in aqueous medium was investigated by UV-activated peroxymonosulfate(PMS).A significant improvement in degradation rate by increasing UV intensity and PMS concentration while the decrease in degradation efficiency with the increase of solution p H and initial concentration of MTX was observed.The proposed UV/PMS process could achieve more than 90%MTX degradation in 30 min with a good mineralization degree(65%).A pseudofirst order kinetic model was employed and successfully predicted the degradation of MTX.The effect of other operational parameters such as the initial concentration of the targeted compound,dosage of oxidant(PMS),solution p H and UV intensity on the degradation rate were investigated.At the last,the main transform intermediates were identified using LC–MS and possible degradation pathways were proposed.The results show that UV/PMS can be used as an efficient technology to treat pharmaceuticals such as methotrexate containing water and wastewater.

Statistical study of EUV and X-ray transient brightenings

Using the visual inspection and base difference method and data from the X-ray Telescope （XRT） onboard Hinode and TRACE with improved spatial and temporal resolution, we selected 48 X-ray transient brightenings （XTBs） and 237 EUV transient brightenings （ETBs） to study the connection between these two types of transient brightenings （TBs）. These ETBs and XTBs have smaller areas （8.42 Mm^2 and 36.3 Mm^2, respectively, on average） and shorter durations （9.0 min and 6.9 min, respectively, on average） than previous studies. These XTBs show three types of morphological structure： point-like, single-loop and multiple-loop. We find only 20% of the ETBs have corresponding XTBs while the other 80% have no X-ray signatures at all. This is presumably due to the small amount of released energy, which is not enough to heat the plasma to coronal temperatures which produce X-ray emission rather than being due to the limitation of spatial resolution and temperature sensitivity of the X-ray instrument. These small ETBs may significantly contribute to the coronal heating.

Observations of EUV and soft X-ray recurring jets in an active region

We present simultaneous observations of three recurring jets in EUV and soft X-ray （SXR）, which occurred in an active region on 2007 June 5. By comparing their morphological and kinematic characteristics in these two different wavelengths, we found that EUV and SXR jets had similar locations, directions, sizes and velocities. We also analyzed their spectral properties by using six spectral lines from the EUV Imaging Spectrometer （EIS） onboard Hinode and found that these jets had temperatures from 0.05 to 2.0MK and maximum electron densities from 6.6× 10^9 to 3.4× 10^10cm^-3. For each jet, an elongated blue-shifted component and a red- shifted component at the jet base were simultaneously observed in the Fe XII A195 and the He II A256 lines. The three jets had maximum Doppler velocities from 25 to 121 km s-1 in the FexII A195 line and from 115 to 232 km s -1 in the HeII A256 line. They had maximum non-thermal velocities from 98 to 181 km s-1 in the Fe xII A195 line and from 196 to 399 km s-1 in the He II A256 line. We also examined the relationship between averaged Doppler velocities and maximum ionization temperatures of these three jets and found that averaged Doppler velocities decreased with the increase of maximum ionization temperatures. In the photosphere, magnetic flux emergences and cancelations continuously took place at the jet base. These observa- tional results were consistent with the magnetic reconnection jet model, implying that magnetic reconnection between emerging magnetic flux and ambient magnetic field occurred in the lower atmosphere.

Obtaining space-based SDO/AIA solar UV and EUV images from ground-based Hαobservations by deep learning

In this work,we explore the mappings from solar images taken in Hα(6563 A)by the Global Oscillation Network Group(GONG)on the ground to those observed in eight different wavelengths(94,131,171,193,211,304,335 and 1600 A)by SDO/AIA in space.Eight mappings are built by training the conditional Generative Adversarial Networks(cGANs)on datasets with 500 paired images,which are[Hα,AIA94],[Hα,AIA131],[Hα,AIA171],[Hα,AIA193],[Hα,AIA211],[Hα,AIA304],[Hα,AIA335]and[Hα,AIA1600].We evaluate the eight trained cGANs models on validation and test datasets with 154-pair images and 327-pair images,respectively.The model generated fake AIA images match the corresponding observed AIA images well on large-scale structures such as large active regions and prominences.But the small-scale flare loops and filament threads are difficult to reconstruct.Four quantitative comparisons are carried out on the validation and test datasets to score the mappings.We find that the model-generated images in 304 and 1600 A match the corresponding observed images best.This exploration suggests that the cGANs are promising methods for mappings between ground-based Ha and space-based EUV/UV images,while some improvements are necessary.

Small-Scale Brightenings in the UV Continuum of an M9.1 Solar Flare

We analyze an M9.1 two-ribbon solar flare which occurred on 2004 July 22 using the TRACE white-light and 1700 A images, the RHESSI, and the SOHO/MDI data. We find many small-scale fast-varying brightenings that appeared in the white-light and 1700 A images along the flare ribbons. Some of them underwent rapid motions in weak magnetic field regions. We identify these short-lived brightenings as UV continuum enhancement. Our preliminary result shows that the brightenings are closely related to the HXR emission. They have a lifetime of 30-60 s and a typical size of about 1＂-2＂. The intensity enhancement is about 150-200 times the mean value of the quiet-Sun. According to previous works, we infer that the 1700A enhancement may be dominated by the increased emission of 1680A continuum coming from the temperature minimum region. The impulsive feature in the 1700 A light curves of the small-scale brightenings may be due to the irradiation of the impulsive CIv line intensity caused by the bombardment of non-thermal electron beams.

Propagating disturbances along a coronal loop from simultaneous EUV imaging and spectroscopic observations

Propagating disturbances（PDs） were studied along an active region loop using simultaneous imaging and spectroscopy. An image sequence recorded in the Fe Ⅸ/Fe X 171 channel, from TRACE and spectral data in the Si Ⅻ 520.6 line obtained from CDS/SOHO, are analyzed. A space-time map constructed from the TRACE image sequence shows the presence of PDs close to the loop foot point propagating with an apparent speed of 39 km s-1. The periodicity was found to be 5.4 min.The corresponding spectroscopic data from CDS, at a location away from the foot point, show oscillations in all three line parameters roughly at the same period. At locations farther from the foot point, the line width oscillation seems to disappear while the Doppler velocity oscillation becomes prominent. We attribute this to the signature of propagating slow waves that get affected by flows/other events close to the foot point. Spectral line profiles do not show much asymmetry, however, it is difficult to infer anything due to the broadened Gaussian shape of the CDS line profiles.

The Solar Upper Transition Region Imager(SUTRI)Onboard the SATech-01 Satellite

The Solar Upper Transition Region Imager(SUTRI)onboard the Space Advanced Technology demonstration satellite(SATech-01),which was launched to a Sun-synchronous orbit at a height of~500 km in 2022 July,aims to test the on-orbit performance of our newly developed Sc/Si multi-layer reflecting mirror and the 2k×2k EUV CMOS imaging camera and to take full-disk solar images at the Ne VII 46.5 nm spectral line with a filter width of~3 nm.SUTRI employs a Ritchey-Chrétien optical system with an aperture of 18 cm.The on-orbit observations show that SUTRI images have a field of view of~416×416 and a moderate spatial resolution of~8″without an image stabilization system.The normal cadence of SUTRI images is 30 s and the solar observation time is about16 hr each day because the earth eclipse time accounts for about 1/3 of SATech-01's orbit period.Approximately15 GB data is acquired each day and made available online after processing.SUTRI images are valuable as the Ne VII 46.5 nm line is formed at a temperature regime of~0.5 MK in the solar atmosphere,which has rarely been sampled by existing solar imagers.SUTRI observations will establish connections between structures in the lower solar atmosphere and corona,and advance our understanding of various types of solar activity such as flares,filament eruptions,coronal jets and coronal mass ejections.