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"ultraviolet"
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Ultraviolet Radiation From a Plant Perspective: The Plant-Microorganism Context
Ultraviolet (UV) radiation directly affects plants and microorganisms, but also alters the species-specific interactions between them. The distinct bands of UV radiation, UV-A, UV-B, and UV-C have different effects on plants and their associated microorganisms. While UV-A and UV-B mainly affect morphogenesis and phototropism, UV-B and UV-C strongly trigger secondary metabolite production. Short wave (<350 nm) UV radiation negatively affects plant pathogens in direct and indirect ways. Direct effects can be ascribed to DNA damage, protein polymerization, enzyme inactivation and increased cell membrane permeability. UV-C is the most energetic radiation and is thus more effective at lower doses to kill microorganisms, but by consequence also often causes plant damage. Indirect effects can be ascribed to UV-B specific pathways such as the UVR8-dependent upregulated defense responses in plants, UV-B and UV-C upregulated ROS accumulation, and secondary metabolite production such as phenolic compounds. In this review, we summarize the physiological and molecular effects of UV radiation on plants, microorganisms and their interactions. Considerations for the use of UV radiation to control microorganisms, pathogenic as well as non-pathogenic, are listed. Effects can be indirect by increasing specialized metabolites with plant pre-treatment, or by directly affecting microorganisms.
Journal Article
The UPDATE trial (UVBPhototherapy in Dermatology for ATopic Eczema): study protocol for a randomized controlled trial of narrowband UVB with optimal topical therapy versus optimal topical therapy in patients with atopic eczema
Background
Narrowband ultraviolet B (NB-UVB) phototherapy is commonly prescribed for patients with moderate-to-severe atopic eczema (AE). The efficacy of NB-UVB, however, has not yet properly been established, as current evidence is of low certainty. Our aim is to assess the short-term and long-term (cost-)effectiveness and safety of NB-UVB in adult AE patients by performing a pragmatic, multicenter, prospective, randomized, open-label, blinded-endpoint (PROBE) trial. This protocol outlines its methodology.
Methods
A pragmatic, multicenter, PROBE trial will be performed with 1:1 randomization of 316 adult patients with moderate-to-severe AE who have inadequate disease control with topical therapy and who are eligible for optimal topical therapy (OTT) or NB-UVB in combination with OTT as a next step. Participants in the interventional arm will receive a minimum of 3 months of OTT combined with 8 to 16 weeks of NB-UVB. The control group receives 3 months of OTT. Following the interventional phase, follow-up will continue for 9 months. Physician-reported and patient-reported outcomes (according to the Harmonising Outcome Measures for Eczema (HOME) Core Outcome Set) and adverse events are assessed at 4 weeks, 3, 6, 9, and 12 months.
Discussion
The UPDATE trial aims to provide high-quality evidence regarding the (cost-)effectiveness and safety of NB-UVB phototherapy in moderate-to-severe AE patients. Challenges that are addressed in the protocol include the possible bias arising from applying open-label treatment and the necessity of introducing OTT into the study design to prevent a high dropout rate.
Trial registration
ClinicalTrials.gov NCT05704205. Registered on December 8, 2022.
Journal Article
Ultraviolet photodetectors based on wide bandgap semiconductor: a review
Ultraviolet (UV) photodetectors (PDs) are effective devices that convert UV radiation energy into electrical signals, and they are widely used in aerospace, chip manufacturing and other fields. At present, the design and manufacture of UV PDs based on wide bandgap semiconductor materials is also an important branch of optoelectronics technology. Wide bandgap semiconductor materials with strong UV absorption, high carrier mobility, exciton binding energy, and temperature resistance, have become ideal materials for fabricating high-performance UV PDs. Meanwhile, some novel materials have also been found to be suitable for the fabrication of UV optoelectronic devices in recent years, such as chalcogenide materials, double-layer hydroxide materials, and graphene-based materials. In this review, the research progress performance parameters, structures and commonly used materials of UV PDs is systematically introduced. In addition, the methods for optimizing device performance based on various property effects of materials are discussed in detail. The broad research prospect of some novel materials and corresponding application in UV PDs are explored, which provide a reference for future research and development of UV PDs.
Journal Article
Inflammatory Molecules Associated with Ultraviolet Radiation-Mediated Skin Aging
Skin is the largest and most complex organ in the human body comprised of multiple layers with different types of cells. Different kinds of environmental stressors, for example, ultraviolet radiation (UVR), temperature, air pollutants, smoking, and diet, accelerate skin aging by stimulating inflammatory molecules. Skin aging caused by UVR is characterized by loss of elasticity, fine lines, wrinkles, reduced epidermal and dermal components, increased epidermal permeability, delayed wound healing, and approximately 90% of skin aging. These external factors can cause aging through reactive oxygen species (ROS)-mediated inflammation, as well as aged skin is a source of circulatory inflammatory molecules which accelerate skin aging and cause aging-related diseases. This review article focuses on the inflammatory pathways associated with UVR-mediated skin aging.
Journal Article
Nicotinamide for Skin-Cancer Chemoprevention in Transplant Recipients
In a placebo-controlled trial involving immunosuppressed organ-transplant recipients, oral nicotinamide (500 mg twice daily) for 12 months did not lead to lower numbers of keratinocyte cancers or actinic keratoses.
Journal Article
Role of Matrix Metalloproteinases in Photoaging and Photocarcinogenesis
Matrix metalloproteinases (MMPs) are zinc-containing endopeptidases with an extensive range of substrate specificities. Collectively, these enzymes are able to degrade various components of extracellular matrix (ECM) proteins. Based on their structure and substrate specificity, they can be categorized into five main subgroups, namely (1) collagenases (MMP-1, MMP-8 and MMP-13); (2) gelatinases (MMP-2 and MMP-9); (3) stromelysins (MMP-3, MMP-10 and MMP-11); (4) matrilysins (MMP-7 and MMP-26); and (5) membrane-type (MT) MMPs (MMP-14, MMP-15, and MMP-16). The alterations made to the ECM by MMPs might contribute in skin wrinkling, a characteristic of premature skin aging. In photocarcinogenesis, degradation of ECM is the initial step towards tumor cell invasion, to invade both the basement membrane and the surrounding stroma that mainly comprises fibrillar collagens. Additionally, MMPs are involved in angiogenesis, which promotes cancer cell growth and migration. In this review, we focus on the present knowledge about premature skin aging and skin cancers such as basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma, with our main focus on members of the MMP family and their functions.
Journal Article
The World Space Observatory Ultraviolet (WSO–UV), as a bridge to future UV astronomy
Ultraviolet (UV) astronomy is a vital branch of space astronomy. Many dozens of short-term UV-experiments in space, as well as long-term observatories, have brought a very important knowledge on the physics and chemistry of the Universe during the last decades. Unfortunately, no large UV-observatories are planned to be launched by most of space agencies in the coming 10–15 years. Conversely, the large UVOIR observatories of the future will appear not earlier than in 2030s. This paper briefly describes the projects that have been proposed by various groups. We conclude that the World Space Observatory–Ultraviolet (WSO–UV) will be the only 2-m class UV telescope with capabilities similar to those of the HST for the next decade. The WSO–UV has been described in detail in previous publications, and this paper updates the main characteristics of its instruments and the current state of the whole project. It also addresses the major science topics that have been included in the core program of the WSO–UV, making this core program very relevant to the current state of the UV-astronomy. Finally, we also present here the ground segment architecture that will implement this program.
Journal Article
In-situ fabrication of PtSe2/GaN heterojunction for self-powered deep ultraviolet photodetector with ultrahigh current on/off ratio and detectivity
The research of ultraviolet photodetectors (UV PDs) have been attracting extensive attention, due to their important applications in many areas. In this study, PtSe
2
/GaN heterojunction is in-situ fabricated by synthesis of large-area vertically standing two-dimensional (2D) PtSe
2
film on n-GaN substrate. The PtSe
2
/GaN heterojunction device demonstrates excellent photoresponse properties under illumination by deep UV light of 265 nm at zero bias voltage. Further analysis reveals that a high responsivity of 193 mA·W
–1
, an ultrahigh specific detectivity of 3.8 × 10
14
Jones, linear dynamic range of 155 dB and current on/off ratio of ~ 108, as well as fast response speeds of 45/102 μs were obtained at zero bias voltage. Moreover, this device response quickly to the pulse laser of 266 nm with a rise time of 172 ns. Such high-performance PtSe
2
/GaN heterojunction UV PD demonstrated in this work is far superior to previously reported results, suggesting that it has great potential for deep UV detection.
Journal Article
Exploratory clinical trial on the safety and bactericidal effect of 222-nm ultraviolet C irradiation in healthy humans
Surgical site infection is one of the most severe complications of surgical treatments. However, the optimal procedure to prevent such infections remains uninvestigated. Ultraviolet radiation C (UVC) with a short wavelength has a high bactericidal effect; however, it is cytotoxic. Nonetheless, given that UVC with a wavelength of 222 nm reaches only the stratum corneum, it does not affect the skin cells. This study aimed to investigate the safety of 222-nm UVC irradiation and to examine its skin sterilization effect in healthy volunteers. This trial was conducted on 20 healthy volunteers. The back of the subject was irradiated with 222-nm UVC at 50-500 mJ/cm.sup.2, and the induced erythema (redness of skin) was evaluated. Subsequently, the back was irradiated with a maximum amount of UVC not causing erythema, and the skin swabs before and after the irradiation were cultured. The number of colonies formed after 24 hours was measured. In addition, cyclobutene pyrimidine dimer (CPD) as an indicator of DNA damage was measured using skin tissues of the nonirradiated and irradiated regions. All subjects experienced no erythema at all doses. The back of the subject was irradiated at 500 mJ/cm.sup.2, and the number of bacterial colonies in the skin swab culture was significantly decreased by 222-nm UVC irradiation. The CPD amount produced in the irradiated region was slightly but significantly higher than that of the non-irradiated region. A 222-nm UVC at 500 mJ/cm.sup.2 was a safe irradiation dose and possessed bactericidal effects. In the future, 222-nm UVC irradiation is expected to contribute to the prevention of perioperative infection.
Journal Article