Intense Ultraviolet Radiation Research Articles

Natural weathering effects of nonwoven geotextile exposed to different climate conditions

Humidity, air temperature, rainfall and solar radiation all contribute to the weathering of geosynthetics. Over time, the useful life can be affected and changes in properties can be observed, which affects the performance of these materials. As geosynthetics durability analyses must encompass each work condition, assessing the climate effects is essential for design purposes. This study exposed a nonwoven needle-punched poly(ethylene) terephthalate geotextile to natural weathering in three Brazilian cities (different exogenous environments) for 18 months. Mechanical tests were conducted to evaluate the geotextile changes due to weathering. This was demonstrated by the results: exposure to weather leads to the deterioration of the geotextile mechanical properties and increased stiffness. After four months, the tensile strength fell by half, while the deformation needed more than twelve months to have this same reduction; ultraviolet radiation intensity was the most effective weathering condition in the field; humidity and rainfall can affect the stiffness of geotextiles; the impact of accumulated climate factors gradually showed a convergence in the response of geotextile to weathering. Thus, this work highlights the need to evaluate the climate conditions in each location to understand the material's behavior on the exposure time.

Comparative skin histological and transcriptomic analysis of Rana kukunoris with two different skin colors

This study compares the skin structures of Rana kukunoris with two different skin colors living in the same area of Haibei in the Northeastern Qinghai-Tibet Plateau. The skin thickness of the khaki R. kukunoris was significantly greater than that of the brown R. kukunoris (P < 0.01), and significantly more mucous and granular glands were present on the dorsal skin of the khaki frog (P < 0.05). Meanwhile, the melanocytes on the dorsal skin of the brown frog were significantly larger than those on the khaki one (P < 0.05). Morphological changes in the expansion and aggregation of melanocytes seemed to deepen the skin color of R. kukunoris. Moreover, transcriptome sequencing identified tyrosine metabolism, melanogenesis, and riboflavin metabolism as the main pathways involved in melanin formation and metabolism in brown R. kukunoris. TYR, MC1R was upregulated as the skin color of R. kukunoris was deepened and contributed to melanin production and metabolism. In contrast, the khaki frog had significantly more upregulated genes and metabolic pathways related to autoimmunity. The khaki frog appeared to defend against ultraviolet (UV) radiation-induced damage by secreting mucus and small molecular peptides, whereas the brown frog protected itself by distributing a large amount of melanin. Hence, the different skin colors of R. kukunoris might represent different adaptation strategies for survival in the intense UV radiation environment of the Qinghai-Tibet Plateau.

UV-B Halotolerant Bacteria from Marakkanam Saltpan and Biology of UV-B Tolerant Pontibacillus salipaludis Based on Whole Genome Sequencing

Saltpans in South India experience intense sunlight and ultraviolet radiation (UV). Therefore, it was hypothesized that halophilic bacteria living there could tolerate UV radiation. To test this, sediment and water samples from the Marakkanam Saltpan were collected and exposed to an artificial UV-B lamp. After irradiation, an aliquot of the sample was spread on nutrient agar (prepared in sterilized source water), and two bacterial strains were obtained, named SBO and SBY. Based on 16S rRNA gene phylogeny, these strains were identified as Bacillus sp. and Pontibacillus salipaludis, respectively. Another aliquot of the UV-B-exposed sample was inoculated into the nutrient broth (in sterilized source water), and incubated for a week in the dark. Later, it was subjected to Illumina MiSeq-based sequencing for the V3-V4 region (16S rRNA gene). Results revealed the presence of 13 bacterial phyla. However, the phylum Bacillota (48.59%) and Pseudomonadota (27.36%) accounted for more than 75% of the diversity. Pontibacillus was the most abundant genus, accounting for 44% of total bacterial diversity. The whole genome of P. salipaludis was sequenced on Illumina HiSeqX to decipher possible genes and pathways involved in UV-B tolerance. The genome size was estimated to be 4.05 MB, with a mean G + C content of 40.82%. RASTtk-based genome annotation revealed 4217 coding sequences and 78 RNAs. Related to the UV-B tolerance, sixteen genes involved in carotenoid and prodigiosin biosynthetic pathways were found. antiSMASH showed the presence of terpene-type carotenoids. More than sixty genes involved in various DNA repair pathways were found.

Functional coatings with carbon quantum dots for solar cells

Currently, research in the world of science is expanding in the field of improving the design parameters of photoconverters, ensuring an increase in their coefficient of performance (efficiency) and an increase in service life. The purpose of the research carried out by the authors of this article is to create a functional coating of solar cell surfaces that is resistant to ultraviolet radiation, allowing to reduce the degree of wear of the active material and increase the overall efficiency of converting solar energy into electrical energy. To confirm the formulated scientific hypothesis about the feasibility of creating functional coatings on the surfaces of photoconverters from materials with carbon quantum dots (CQDs), a special installation was developed and a series of experiments was carried out using a solution of CQDs in xylene, analytical grade isopropyl alcohol, and LA grade polyvinyl butyral. The research results obtained indicate an improvement in the output characteristics of solar cells due to the use of coatings made of materials with carbon quantum dots, including an increase in the overall efficiency. Solar cells provided with the proposed coatings will be in demand for operation in conditions where intense ultraviolet radiation dominates and maximum energy efficiency from solar panels is required: high mountains and open space. The practical application of the developed coatings will increase the efficiency of solar cells by 1–3% and increase their service life by absorbing harmful UV rays that destroy the active material by at least 10%.

Indole-3-acetic acid improves periphyton's resistance to ultraviolet-B: From physiological-biochemical properties and bacteria community to livestock-polluted water purification

Livestock-polluted water is a pressing water environmental issue in plateau pastoral regions, necessitating the adoption of eco-friendly solutions. Despite periphyton being a promising alternative, its efficacy is limited by the prevalence of intense ultraviolet radiation, particularly ultraviolet-B (UVB), in these regions. Therefore, this study employs molecular tools and small-scale trials to explore the crucial role of indole-3-acetic acid (IAA) in modulating periphyton characteristics and mediating nutrient removal from livestock-polluted water under UVB exposure. The results revealed that IAA augments periphyton's resilience to UVB stress through several pathways, including increasing periphyton's biomass, producing more extracellular polymeric substances (EPS), and enhancing antioxidant enzyme activities and photosynthetic activity of periphyton. Moreover, IAA addition increased periphyton's bacterial diversity, reshaped bacterial community structure, enhanced community stability, and elevated the R2 value of neutral processes in bacterial assembly from 0.257 to 0.651 under UVB. Practically, an IAA concentration of 50 mg/L was recommended. Small-scale trials confirmed the effectiveness of IAA in assisting UVB-stressed periphyton to remove nitrogen and phosphorus from livestock-polluted water, without the risk of nitrogen accumulation. These findings offer valuable insights into the protection of aquatic ecosystems in plateau pastoral regions based on periphyton property in an eco-friendly manner.

Adaptive evidence of mitochondrial genes in Pteromalidae and Eulophidae (Hymenoptera: Chalcidoidea).

Pteromalidae and Eulophidae are predominant and abundant taxa within Chalcidoidea (Hymenoptera: Apocrita). These taxa are found in diverse ecosystems, ranging from basin deserts (200 m) to alpine grasslands (4500 m). Mitochondria, cellular powerhouses responsible for energy production via oxidative phosphorylation, are sensitive to various environmental factors such as extreme cold, hypoxia, and intense ultraviolet radiation characteristic of alpine regions. Whether the molecular evolution of mitochondrial genes in these parasitoids corresponds to changes in the energy requirements and alpine environmental adaptations remains unknown. In this study, we performed a comparative analysis of mitochondrial protein-coding genes from 11 alpine species of Pteromalidae and Eulophidae, along with 18 lowland relatives, including 16 newly sequenced species. We further examined the codon usage preferences (RSCU, ENC-GC3s, neutrality, and PR2 bias plot) in these mitochondrial protein-coding sequences and conducted positive selection analysis based on their Bayesian phylogenetic relationships, and identified positive selection sites in the ATP6, ATP8, COX1, COX3, and CYTB genes, emphasizing the crucial role of mitochondrial gene adaptive evolution in the adaptation of Pteromalidae and Eulophidae to alpine environments. The phylogenetically independent contrast (PIC) analysis results verified the ω ratio of 13 PCGs from Pteromalidae and Eulophidae increased with elevation, and results from generalized linear model confirm that ATP6, ATP8, COX3, and ND1 are closely correlated with temperature-related environmental factors. This research not only enriched the molecular data of endemic alpine species but also underscores the significance of mitochondrial genes in facilitating the adaptation of these minor parasitoids to plateau habitats.

Asphaltenes from Heavy Crude Oil as Ultraviolet Stabilizers against Polypropylene Aging.

The destruction of polymers under the influence of ultraviolet (UV) radiation is the cause of their aging and deterioration of strength properties. Asphaltenes are low-value waste products after the refining and deasphalting of heavy crude oil, which absorb UV radiation well. Asphaltenes require rational utilization, which suggests their use as UV stabilizing agents for polymers. In this work, asphaltenes were used to prevent UV aging of polypropylene (PP) by adding them in a mass fraction from 5% to 30% within an asphaltene/PP composite material. Rheometry, calorimetry, X-ray diffraction analysis, and tensile strength of PP films containing asphaltenes were performed before and after their intense UV irradiation for accelerated aging. Asphaltenes slightly reduce the viscosity, crystallinity, and mechanical strength of the initial PP due to their plasticizing effect. However, this deterioration in properties is more than compensated when studying UV-aged samples. Intense UV aging causes multiple catastrophic drops in the viscosity and strength of pure PP with the preservation of crystallinity due to the break of polymer chains and a decrease in molecular weight by approximately eight times. Asphaltenes suppress the destruction of PP, which is expressed in a significantly smaller decline in its viscosity and strength due to UV aging. The most optimal content of asphaltenes is 20%, which suppresses UV destruction by six times and best preserves the strength properties of PP.

Experiment on the formaldehyde removal performance of TiO2 coating agent for finishing materials

As the frequency of indoor habitation escalates and advancements in building technology optimize airtightness, the importance of maintaining high-quality indoor air has grown increasingly critical. This urgency is further amplified by the proliferation of chemical building materials, necessitating more effective strategies for air pollutant abatement. To address this need, the current study explored the utility of titanium dioxide photocatalysts, which possess chemical decomposition capabilities, as a means of improving air quality within indoor environments. To verify the effectiveness of this approach, the research focused on the removal of formaldehyde—a quintessential indoor air pollutant—by incorporating a titanium dioxide photocatalyst into a coating agent commonly employed in construction materials. Notably, ultraviolet (UV) light, essential for activating the photocatalytic process, is generally absent in indoor settings. To mitigate this limitation, a consistent source of UV radiation was provided through the use of an UV lamp. Adhering to protocols outlined by the International Organization for Standardization, we employed a photoreactor to evaluate the photocatalytic efficiency of the composite material under varying intensities of UV radiation and reactor volumes. The results unequivocally confirmed that variations in UV radiation intensity and reactor volume significantly influenced the photocatalytic effectiveness of the material, resulting in a demonstrable reduction in pollutant concentrations. These findings suggest the feasibility of utilizing titanium dioxide photocatalysts for mitigating outdoor air pollutants, where natural UV radiation is more readily available. However, for indoor applications, the absence of naturally occurring UV radiation presents a considerable challenge. Overcoming this constraint could facilitate the indoor application of photocatalytic coatings, as informed by the optimal conditions of low pollutant reactivity and robust UV radiation revealed in this study, thereby substantially enhancing indoor air quality.

Thermal Effects in Up-Conversion Luminescence NaYF4: Tm3+, Yb3+ Core-Shell Nanoparticles in the Temperature Range of 18-312 K.

This work demonstrates the temperature (18-312 K) impact on Tm3+ up-conversion luminescence in core-shell structured NaYF4:Tm3+, Yb3+ nanoparticles excited at 976 nm. As the temperature decreases from room temperature to 18 K, Tm3+ up-conversion luminescence bands intensities greatly increase, an average of 60-fold, emitting intense blue and ultraviolet radiation. Tm3+ up-conversion luminescence spectra measurements at different temperatures reveal that three thermal quenching mechanisms are responsible for observed variations in Tm3+ up-conversion luminescence spectra. These three quenching mechanisms are related to the excitation radiation absorption, Stark sublevel population, and energy transfer from Yb3+ to Tm3+.

High voltage response of graphene/4H-SiC UV photodetector with low level detection

A self-powered graphene/silicon carbide (G/4H-SiC) ultraviolet photodetector of a p-i-n like-structure with high voltage response has been fabricated to detect and measure low intensity ultraviolet (UV) radiation. Bilayer graphene sheet grown by chemical vapor deposition (CVD) method was transferred on the top of an epilayer structure of n-/n+ 4 H-SiC. In this structure, two Schottky contacts were formed: one at G/ n- 4H-SiC interface and the other at bulk-4 H-SiC/Cr/Au interface. The photodetector's characteristic measurements revealed low dark current of ∼ 0.58 nA and spectral voltage responsivity of ∼ 0.75 V/W at 300 nm wavelength. Under low level UV illumination of 300 nm wavelength, the photodetector exhibited a leakage current and a photogenerated response voltage of 1.1 nA and 10 mV, respectively. The time-dependent photovoltage measurements displayed a rapid photovoltage response with rise and decay times of ∼74 ns and ∼ 580 ns, respectively. This novel device holds promise for applications requiring sensitive and self-powered UV detection.

Alleviation of ultraviolet-B radiation-induced photoaging using Saussurea medusa Maxim polysaccharide.

Saussurea medusa polysaccharide, the polysaccharide extract of Saussurea medusa Maxim, a traditional Chinese herbal medicine, is used to combat intense ultraviolet radiation, cold, and hypoxia in patients, as well as during drought. This polysaccharide has rich medicinal and ecological values. We aimed to determine whether saussurea medusa polysaccharides can reduce ultraviolet B (UVB)-induced skin photoaging. Seventy-five male Kunming mice were divided into five groups: control, UVB-only, UVB plus vitamin E (VE group), UVB plus saussurea medusa (2 g/kg), and UVB plus saussurea medusa (6 g/kg). The control group was irradiated with normal light, while the other four groups were subcutaneously administered 10 mL/kg/day D-galactose and irradiated with narrow-spectrum UVB for 40 min daily. From day 11, the VE group was administered 0.25 g/kg/day vitamin E, while the saussurea medusa intervention groups were administered 2 and 6 g/kg/day saussurea medusa polysaccharide. After 30 days of continuous administration, treatment with saussurea medusa polysaccharides was found to reduce UVB-induced skin photoaging in mice by elevating the levels of superoxide dismutase, glutathione peroxidase, and hydroxyproline (HYP), while reducing the level of MDA, and inhibiting the EGFR/MEK/ERK/c-Fos pathway. Overall, our findings suggest that treatment with saussurea medusa polysaccharides positively influences skin photoaging.

Upward migration of calanoid copepods is driven by high food quality in surface waters in an alpine lake

Abstract The diel vertical migration of zooplankton includes downward migration to deep water during the day and upward migration to surface water at night. Diurnal downward migration has been well explained; zooplankton migration to surface water at night remains unclear. This study aimed to explore the reason of the nocturnal upward migration of the calanoid copepod Arctodiaptomus sp. In Lake Heihai, an alpine lake (elevation 4,090 m above sea level) without predators. Herein, we present the vertical profiles of the lake, including water temperature, chlorophyll a (Chl‐a), fatty acids, and astaxanthin synthesis precursors (ASPs) of seston in the water column. The distributions and concentrations of fatty acids and astaxanthin in Arctodiaptomus sp. were characterised through field investigations during the day and at night. Meanwhile, the effect of ultraviolet radiation (UVR) on ASPs in seston was explored through indoor experiments. Lake Heihai had the characteristics of low temperature, low food availability, high transparency, and high UVR intensity. Arctodiaptomus sp. was distributed in water layers below 6 m during the day and throughout the water column at night. Arctodiaptomus sp. accumulated large amounts of fatty acids, especially polyunsaturated fatty acids (PUFAs), and inhibitors of fatty acid oxidation–astaxanthin in the cold alpine lake. The concentrations of lutein, a kind of ASP, and PUFAs in seston were highest in surface waters. The indoor experiment verified that UVR can enhance the synthesis of ASP. The calanoids migrated to surface waters at night to obtain ASPs and PUFAs in seston, which were at high concentrations in surface waters. PUFAs and ASP may be of high food quality for zooplankton in alpine lakes. The findings indicated that the upward migration of Arctodiaptomus sp. at night was driven by the high quality of food sources (PUFAs and ASP) in surface waters. Arctodiaptomus sp. adapts behaviour and physiology to the environment of the alpine lake. We explored why zooplankton migrated to surface waters at night from the perspective of their physiological characteristics and adaptability to the environment. Our findings provide a new way to investigate the diel vertical migration of zooplankton, especially in alpine lakes.

Different UV-B exposure times induce phenotypic, transcriptomic, and proteomic changes in wine grape leaves

The Shangri-La region, located in southwest China, is known for its dry climate and intense UltraViolet (UV) radiation due to its high altitude. Research conducted in the past has demonstrated that UV radiation, particularly UV-B radiation, enhances plants' ability to withstand cold temperatures, diseases, and arid conditions. Indeed, the Cabernet Sauvignon grape variety, predominantly cultivated in Shangri-La where the UV intensity reaches 21–22w/m2, has displayed remarkable resilience in recent decades. However, the specific impact of UV-B radiation on Cabernet Sauvignon grape leaves has yet to be fully understood. Consequently, our objective is to investigate the influence of UV radiation on grapes grown at high altitudes. To gain insights into the short-term effects on grape leaves, we conducted a comprehensive investigation involving anatomical and photosynthetic changes. Additionally, we analyzed the transcriptomic and proteomic regulation associated with these changes following exposure to UV-B radiation at intensities ranging from 15–20w/m2 for durations of 3 and 7 days.The findings of our study demonstrated that exposure to UV-B radiation, particularly at intensities surpassing 10w/m2, led to noticeable changes in the morphology of epidermal and palisade tissue cells. Furthermore, after a 3-day exposure to UV-B, we observed an upregulation of proteins responsible for cytoskeletal organization and cell wall synthesis. Conversely, following a 7-day treatment, proteins associated with disease resistance and antioxidants showed increased expression. Transcriptomic analysis revealed a significant enrichment of proteins and genes linked to pathogen infection, defense mechanisms, and antioxidant processes. Overall, our research highlighted the positive impact of intense UV radiation at high altitudes on enhancing disease resistance and environmental adaptability in Cabernet Sauvignon grape plants.

Multi-Watt cavity for 266 nm light in vacuum

Intense coherent ultraviolet radiation is gaining increasing importance in advanced quantum technologies—from optical clocks and quantum computers to matter-wave interferometry—as well as in photochemistry, life sciences, semiconductor industry, and space applications. Since the preparation of multi-Watt light sources is still an open challenge for many ultraviolet wavelengths, resonant enhancement in a cavity is an attractive alternative. However, many experiments with atoms, molecules or nanoparticles require isolation in high vacuum where UV optics often show fast degradation. Here, we present stable performance of a cavity for 266 nm light with several Watt of intra-cavity power in high vacuum despite the presence of hydrocarbons. Comparing two sets of cavity mirrors indicates that this feat is connected to the micro-chemical environment at the topmost coating layer. Our study emphasizes the need for further developments in this direction to facilitate robust, compact, and high-performing devices employing UV radiation.

Inserting Bi atoms on the [WO6] framework: Photochromic WO3/Bi2WO6 nanoparticles enable visual sunlight UV sensing

Photochromic tungsten oxide (WO3) offers incredible prospects for protecting human health by visually sensing ultraviolet (UV) radiation exposure from sunlight. Heterojunction engineering can improve the charge carrier separation efficiency in the photochromic procedure to implement this possibility, but it suffers from the finiteness of crystal phase interfacial contact and/or the complexity of synthetic protocols. Here, the construction of an atomic-scale crystal/amorphous WO3/Bi2WO6 nanoparticle results from introducing Bi atoms on the [WO6] framework to form [Bi2O2] components for in-situs incorporating Bi2WO6 into the WO3 matrix. The absence of well-defined interfaces in WO3/Bi2WO6 type II heterostructures ensures an efficient photoexcited electrons transfer from Bi2WO6 to WO3; abundant WO6 units serve as the sites for rapid capture and consumption of photogenerated electrons to facilitate electron-hole separation. Complexing the efficient photochromic products with hydroxyethyl cellulose, the WO3/Bi2WO6-based photochromic films (PCFs) and a colorimetric card indicating different UV intensities are developed. The invisible UV rays are converted into visible color changes; thus, the UV radiation intensity can be estimated from the dark change in the colored PCFs. This work presents a way to elevate the carrier utilization efficiency in WO3 and delivers candidates for exploring efficient and cost-effective UV radiation sensors.

Scientists find complex aromatic molecules in young, distant galaxy

Astronomers have detected polycyclic aromatic hydrocarbons (PAHs) in a galaxy observed as it was less than 1.5 billion years after the Big Bang, according to a new report ( Nature 2023, DOI: 10.1038/s41586-023-05998-6 ). The findings demonstrate the James Webb Space Telescope’s (JWST) prowess for probing chemistry in deep time. While earthbound chemists might find these complex organic molecules in soot or smog, astronomers seek out PAHs in space to guide them toward newborn stars. When stars first form, they blast out intense ultraviolet (UV) radiation. That UV light photoactivates PAHs, which emit infrared (IR) radiation in turn. So when IR telescopes spot emissions of PAHs, it’s likely because a blazing young star lit them up, says Justin Spilker, an astrophysicist at Texas A&M University. That’s what the Spitzer Space Telescope and others have observed in nearby galaxies, but limited instrument sensitivity has prevented astronomers from glimpsing PAHs in our

Triggering multiple sclerosis at conception and early gestation: The variation in ultraviolet radiation is as important as its intensity

Background and objectivesMedical science needs to further elucidate the role of ultraviolet radiation (UVR), geographic latitude, and the role of vitamin D in the autoimmune disease multiple sclerosis (MS). We separated several papers into categories out of the thousands published and used their conclusions to explore the relationship between UVR and MS. RelevanceMS is increasing in incidence, particularly in women where MS is two to three times that in men and particularly severe in African Americans. MethodsWe collected UVR data at our observatory in Central Maine and calculated the average coefficient of variation (CVUVR) for each month for 15 years (2007–2021, inclusive). ResultsThe month of conception (MOC) is more important than the month of birth (MOB) in explaining how UVR triggers the variable genetic predisposition to MS. We hypothesize that the rapidly increasing CVUVR is important in preventing an increase in the activity of the vitamin D receptor (VDR) from August to December, which then requires a higher intensity of UVR later in life to suppress the immune system, therefore predisposing to more MS. LimitationsOne observatory at about 44° latitude. ConclusionsWhile variation in UVR is important at the MOC if UVR exceeds a threshold (e.g., if the sunspot number equals or is greater than 90, usually at a solar cycle MAX, or at elevations above approximately 3,000 feet above sea level), the MS mitigating vitamin D-VDR mechanism is overwhelmed and the genotoxic effects of higher-intensity UVR promote MS in those with a genetic predisposition. What is new in this researchThis paper offers a new concept in MS research.

Multifunctional and High‐Performance FAPBI3 Quantum Dots/Graphene UV Photodetectors by the Modulation of Photoconductivity

AbstractLow‐dimensional devices with different photoconductive effects attract much attention in optoelectronics. In this work, negative photoconductivity (NPC) monolayer graphene photodetectors are fabricated by chemical vapor deposition (CVD), and a positive photoconductivity (PPC) photodetector is realized by decorating perovskite FAPbI3 quantum dots prepared by a simple and cost‐effective non‐polar solvent synthesis method on a graphene surface. The graphene‐based photodetector exhibits an NPC characteristic, which is attributed to the absorption and desorption of water molecules on the graphene surface. The responsivity of the photodetector with an NPC characteristic is −0.86 A W−1 under intense ultraviolet light irradiation, and the detectivity is −2.45 × 109 Jones. The FAPbI3 quantum dots/graphene photodetector with a PPC feature has a responsivity of 8.03 A W−1 and a detectivity of 1.89 × 1010 Jones under the irradiation of ultraviolet light of 365 nm and 55.3 mW cm−2 intensity. Due to the intense light absorption of perovskite combined with the extremely high mobility of graphene, photodetectors have high exciton separation and photocurrents when the devices are irradiated by ultraviolet light. Individual photodetectors are successfully created with NPC and PPC effects; the critical analysis for the different photoconductive mechanisms is provided, which will benefit the development of future multifunctional systems.

Heat waves accelerate the spread of infectious diseases

COVID-19 pandemic appeared summer surge in 2022 worldwide and this contradicts its seasonal fluctuations. Even as high temperature and intense ultraviolet radiation can inhibit viral activity, the number of new cases worldwide has increased to >78% in only 1 month since the summer of 2022 under unchanged virus mutation influence and control policies. Using the attribution analysis based on the theoretical infectious diseases model simulation, we found the mechanism of the severe COVID-19 outbreak in the summer of 2022 and identified the amplification effect of heat wave events on its magnitude. The results suggest that approximately 69.3% of COVID-19 cases this summer could have been avoided if there is no heat waves. The collision between the pandemic and the heatwave is not an accident. Climate change is leading to more frequent extreme climate events and an increasing number of infectious diseases, posing an urgent threat to human health and life. Therefore, public health authorities must quickly develop coordinated management plans to deal with the simultaneous occurrence of extreme climate events and infectious diseases.

Ultrafast Roaming Mechanisms in Ethanol Probed by Intense Extreme Ultraviolet Free-Electron Laser Radiation: Electron Transfer versus Proton Transfer

Ultrafast H2+ and H3+ formation from ethanol is studied using pump-probe spectroscopy with an extreme ultraviolet (XUV) free-electron laser. The first pulse creates a dication, triggering H2 roaming that leads to H2+ and H3+ formation, which is disruptively probed by a second pulse. At photon energies of 28 and 32 eV, the ratio of H2+ to H3+ increases with time delay, while it is flat at a photon energy of 70 eV. The delay-dependent effect is ascribed to a competition between electron and proton transfer. High-level quantum chemistry calculations show a flat potential energy surface for H2 formation, indicating that the intermediate state may have a long lifetime. The ab initio molecular dynamics simulation confirms that, in addition to the direct emission, a small portion of H2 undergoes a roaming mechanism that leads to two competing pathways: electron transfer from H2 to C2H4O2+ and proton transfer from C2H4O2+ to H2.