Carbon dots show potential in lighting and displays. However, only their fluorescence has been observed so far. Here we report the observation of phosphorescence from carbon dots in a polyvinyl ...alcohol matrix. The phosphorescence is attributed to C=O bonds on the surface of carbon dots and has a very long lifetime (~380 ms).
Hydroxyl radical (•OH) is an active species widely reported in studies across many scientific fields, and hence, its reliable analysis is vitally important. Currently, alcohols are commonly used as ...scavengers for •OH determination. However, the impacts of alcohols on the reliability of •OH detection remain unknown. In this study, we found that adding different types and different amounts of alcohols in water samples treated with ultraviolet irradiation undesirably produced substantial amounts of hydrogen peroxide (H
O
), which is a known •OH precursor. This means that the conventional •OH determination method using alcohols is likely unreliable or even misleading. Through careful investigation, we revealed an overlooked reaction pathway during H
O
and •OH transformations. Varying oxygen concentrations, pHs, alcohol dosages, and types altered H
O
formation, which can affect •OH determination accuracy. Among alcohols,
-butanol is the best scavenger because it quenches •OH rapidly but re-forms little H
O
.
Understanding the fate of plastics in the environment is of critical importance for the quantitative assessment of the biological impacts of plastic waste. Specially, there is a need to analyze in ...more detail the reputed longevity of plastics in the context of plastic degradation through oxidation and fragmentation reactions. Photo-oxidation of plastic debris by solar UV radiation (UVR) makes material prone to subsequent fragmentation. The fragments generated following oxidation and subsequent exposure to mechanical stresses include secondary micro- or nanoparticles, an emerging class of pollutants. The paper discusses the UV-driven photo-oxidation process, identifying relevant knowledge gaps and uncertainties. Serious gaps in knowledge exist concerning the wavelength sensitivity and the dose-response of the photo-fragmentation process. Given the heterogeneity of natural UV irradiance varying from no exposure in sediments to full UV exposure of floating, beach litter or air-borne plastics, it is argued that the rates of UV-driven degradation/fragmentation will also vary dramatically between different locations and environmental niches. Biological phenomena such as biofouling will further modulate the exposure of plastics to UV radiation, while potentially also contributing to degradation and/or fragmentation of plastics independent of solar UVR. Reductions in solar UVR in many regions, consequent to the implementation of the Montreal Protocol and its Amendments for protecting stratospheric ozone, will have consequences for global UV-driven plastic degradation in a heterogeneous manner across different geographic and environmental zones. The interacting effects of global warming, stratospheric ozone and UV radiation are projected to increase UV irradiance at the surface in localized areas, mainly because of decreased cloud cover. Given the complexity and uncertainty of future environmental conditions, this currently precludes reliable quantitative predictions of plastic persistence on a global scale.
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•Data on the fate of environmental plastic are needed to assess biological impacts.•Photo-oxidation of plastic by solar UV radiation makes it prone to fragmentation.•Implementation of the Montreal Protocol has consequences for plastic degradation.•UV-driven plastic degradation varies between locations and environments.•Knowledge gaps exist on wavelength sensitivity and dose-response of degradation.
Wastewaters containing recalcitrant and toxic organic pollutants are scarcely decontaminated in conventional wastewater facilities. Then, there is an urgent challenge the development of powerful ...oxidation processes to ensure their organic removal in order to preserve the water quality in the environment. This review presents the recent development of an electrochemical advanced oxidation process (EAOP) like the photoelectro-Fenton (PEF) process, covering the period 2010–2019, as an effective treatment for wastewater remediation. The high oxidation ability of this photo-assisted Fenton-based EAOP is due to the combination of in situ generated hydroxyl radicals and the photolytic action of UV or sunlight irradiation over the treated wastewater. Firstly, the fundamentals and characteristics of the PEF process are described to understand the role of oxidizing agents. Further, the properties of the homogeneous PEF process with iron catalyst and UV irradiation and the benefit of sunlight in the homogeneous solar PEF one (SPEF) are discussed, supported with examples over their application to the degradation and mineralization of synthetic solutions of industrial chemicals, herbicides, dyes and pharmaceuticals, as well as real wastewaters. Novel heterogeneous PEF processes involving solid iron catalysts or iron-modified cathodes are subsequently detailed. Finally, the oxidation power of hybrid processes including photocatalysis/PEF, solar photocatalysis/SPEF, photoelectrocatalysis/PEF and solar photoelectrocatalysis/SPEF, followed by that of sequential processes like electrocoagulation/PEF and biological oxidation coupled to SPEF, are analyzed.
•Review of the photoelectro-Fenton (PEF) process for wastewater remediation (2010–2019).•Characteristics, operation conditions and application of homogeneous PEF with UV light.•Higher oxidizing power of homogeneous solar PEF (SPEF) than homogeneous PEF.•Heterogeneous PEF with solid iron catalysts or iron-modified cathodes upon UV light.•Combination with photocatalysis, photoelectrocatalyis, electrocoagulation and biological oxidation .
All inorganic CsPbX3 (X = Cl, Br, I) perovskite nanocrystals (PNCs) with 50-85% photoluminescence quantum yields and tunable emission in the range of 440-682 nm have been successfully synthesized at ...room temperature in open air. This facile strategy enables us to prepare gram-scale CsPbBr3 NCs with a PLQY approaching 80%.
Present study proposed the synthesis of mixed p-type and n-type nanocomposite heterostructures by co-precipitation method. The as-synthesized heterostructures were characterized through different ...characterization techniques. The as-synthesized Bi
WO
and Bi
O
-ZnO heterostructures were tested as photocatalysts during the photodegradation of Bisphenol A (BPA). The Bi
O
-ZnO heterostructure nanocomposite was found to be a more effective photocatalyst than Bi
WO
. The effect of operating parameters including catalytic dose (0.02-0.15 gL
), initial BPA concentration (5-20 mgL
), temperature change (5-20 °C) and solution pH changes (4, 5, 7, and 8) were evaluated with Bi
O
-ZnO under UV-light irradiation by selecting a 300 W Xe lamp. More than 90% BPA was degraded with 0.15 gL
Bi
O
-ZnO, keeping 1.0 mM H
O
concentration fixed in 250 mL of reaction suspension. The HPLC and GC-MS were used to detect the reaction intermediates and final products. A plausible degradation pathway was proposed on the basis of the identification of reaction intermediates. Repeatability test analysis confirmed that the as-synthesized catalyst showed superb catalytic performance on its removal trend. The kinetics of degradation of BPA were well fitted by the power laws model. With the order of reaction being 0.6, 0.9, 1.2, and 1.3 for different operating parameters, i.e., catalyst dose, initial pH, temperature, and initial BPA concentration.
UV Signature Mutations Brash, Douglas E.
Photochemistry and photobiology,
January/February 2015, Letnik:
91, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Sequencing complete tumor genomes and exomes has sparked the cancer field's interest in mutation signatures for identifying the tumor's carcinogen. This review and meta‐analysis discusses signatures ...and their proper use. We first distinguish between a mutagen's canonical mutations—deviations from a random distribution of base changes to create a pattern typical of that mutagen—and the subset of signature mutations, which are unique to that mutagen and permit inference backward from mutations to mutagen. To verify UV signature mutations, we assembled literature datasets on cells exposed to UVC, UVB, UVA, or solar simulator light (SSL) and tested canonical UV mutation features as criteria for clustering datasets. A confirmed UV signature was: ≥60% of mutations are C→T at a dipyrimidine site, with ≥5% CC→TT. Other canonical features such as a bias for mutations on the nontranscribed strand or at the 3′ pyrimidine had limited application. The most robust classifier combined these features with criteria for the rarity of non‐UV canonical mutations. In addition, several signatures proposed for specific UV wavelengths were limited to specific genes or species; UV's nonsignature mutations may cause melanoma BRAF mutations; and the mutagen for sunlight‐related skin neoplasms may vary between continents.
Inverse relationship of canonical mutation patterns and mutation signatures for inferring the mutagen from mutations. Two mutagens are illustrated. A mutagen's canonical mutations deviate from random base changes, establishing a pattern typical for that mutagen. Different mutagens can produce the same canonical mutations (non‐informative mutations). Signature mutations are the subset of canonical mutations that, in addition, are unique to that mutagen and permit inference backward from mutations to mutagen. A mutagen therefore produces signature mutations plus non‐informative mutations. The latter are real and are produced by the mutagen, but are not useful for identifying that mutagen or carcinogen.
Droplet microfluidics offers exquisite control over the flows of multiple fluids in microscale, enabling fabrication of advanced microparticles with precisely tunable structures and compositions in a ...high throughput manner. The combination of these remarkable features with proper materials and fabrication methods has enabled high efficiency, direct encapsulation of actives in microparticles whose features and functionalities can be well controlled. These microparticles have great potential in a wide range of bio-related applications including drug delivery, cell-laden matrices, biosensors and even as artificial cells. In this review, we briefly summarize the materials, fabrication methods, and microparticle structures produced with droplet microfluidics. We also provide a comprehensive overview of their recent uses in biomedical applications. Finally, we discuss the existing challenges and perspectives to promote the future development of these engineered microparticles.
In recent years, there has been a growing interest on the occurrence of antibiotic-resistant bacteria (ARB) and antibiotic resistant genes (ARGs) in treated and untreated drinking water. ARB and ARGs ...pose a public health concern when they transfer antibiotic resistance (AR) to human pathogens. However, it is still unclear whether the presence of environmental ARB and ARGs in source water, drinking water treatment plants, and drinking water distribution systems has any significant impact on human exposure to pathogenic ARB. In this review, we critically examine the occurrence of AR in groundwater, surface water, and treated distributed water. This offered a new perspective on the human health threat posed by AR in drinking water and helped in crafting a strategy for monitoring AR effectively. Using existing data on removal of ARB and ARGs in drinking water treatment plants, presence and proliferation of AR in drinking water distribution systems, and mechanisms and pathways of AR transfer in drinking water treatment plants, we conclude that combining UV-irradiation with advanced oxidative processes (such as UV/chlorine, UV/H2O2, and H2O2/UV/TiO2) may enhance the removal of ARB and ARGs, while disinfection may promote horizontal gene transfer from environmental ARB to pathogens. The potential human health risks of AR were determined by examining human exposure to antibiotic resistant human pathogens and re-evaluating waterborne disease outbreaks and their links to environmental AR. We concluded that integrating disease outbreak analysis, human exposure modelling, and clinical data could provide critical information that can be used to estimate the dose-response relationships of pathogenic ARB in drinking water, which is required for accurate risk assessments.
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•Pathogenic antibiotic-resistant bacteria (ARB) have been detected in drinking water.•Disinfection may increase the transfer of antibiotic resistant genes (ARGs) to pathogens.•Combining UV-irradiation and advanced oxidation may enhance ARG and ARB removal.•Antibiotic resistance removal strategies in drinking water are critically examined.•Monitoring priority ARB in drinking water is vital for human health risk assessment.
The rate at which COVID-19 has spread throughout the globe has been alarming. While the role of fomite transmission is not yet fully understood, precise data on the environmental stability of ...SARS-CoV-2 is required to determine the risks of fomite transmission from contaminated surfaces.
This study measured the survival rates of infectious SARS-CoV-2, suspended in a standard ASTM E2197 matrix, on several common surface types. All experiments were carried out in the dark, to negate any effects of UV light. Inoculated surfaces were incubated at 20 °C, 30 °C and 40 °C and sampled at various time points.
Survival rates of SARS-CoV-2 were determined at different temperatures and D-values, Z-values and half-life were calculated. We obtained half lives of between 1.7 and 2.7 days at 20 °C, reducing to a few hours when temperature was elevated to 40 °C. With initial viral loads broadly equivalent to the highest titres excreted by infectious patients, viable virus was isolated for up to 28 days at 20 °C from common surfaces such as glass, stainless steel and both paper and polymer banknotes. Conversely, infectious virus survived less than 24 h at 40 °C on some surfaces.
These findings demonstrate SARS-CoV-2 can remain infectious for significantly longer time periods than generally considered possible. These results could be used to inform improved risk mitigation procedures to prevent the fomite spread of COVID-19.
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