Showing papers on "Ultraviolet light published in 2018"
TL;DR: Sulfate radical-based advanced oxidation processes (AOPs) have received increasing attention in recent years due to their high capability and adaptability for the degradation of emerging contaminants as mentioned in this paper.
2,267 citations
TL;DR: The detection of a flattened absorption profile in the sky-averaged radio spectrum that is largely consistent with expectations for the 21-centimetre signal induced by early stars; however, the best-fitting amplitude of the profile is more than a factor of two greater than the largest predictions.
Abstract: The 21-cm absorption profile is detected in the sky-averaged radio spectrum, but is much stronger than predicted, suggesting that the primordial gas might have been cooler than predicted. As the first stars heated hydrogen in the early Universe, the 21-cm hyperfine line—an astronomical standard that represents the spin-flip transition in the ground state of atomic hydrogen—was altered, causing the hydrogen gas to absorb photons from the microwave background. This should produce an observable absorption signal at frequencies of less than 200 megahertz (MHz). Judd Bowman and colleagues report the observation of an absorption profile centred at a frequency of 78 MHz that is about 19 MHz wide and 0.5 kelvin deep. The profile is generally in line with expectations, although it is deeper than predicted. An accompanying paper by Rennan Barkana suggests that baryons were interacting with cold dark-matter particles in the early Universe, cooling the gas more than had been expected. After stars formed in the early Universe, their ultraviolet light is expected, eventually, to have penetrated the primordial hydrogen gas and altered the excitation state of its 21-centimetre hyperfine line. This alteration would cause the gas to absorb photons from the cosmic microwave background, producing a spectral distortion that should be observable today at radio frequencies of less than 200 megahertz1. Here we report the detection of a flattened absorption profile in the sky-averaged radio spectrum, which is centred at a frequency of 78 megahertz and has a best-fitting full-width at half-maximum of 19 megahertz and an amplitude of 0.5 kelvin. The profile is largely consistent with expectations for the 21-centimetre signal induced by early stars; however, the best-fitting amplitude of the profile is more than a factor of two greater than the largest predictions2. This discrepancy suggests that either the primordial gas was much colder than expected or the background radiation temperature was hotter than expected. Astrophysical phenomena (such as radiation from stars and stellar remnants) are unlikely to account for this discrepancy; of the proposed extensions to the standard model of cosmology and particle physics, only cooling of the gas as a result of interactions between dark matter and baryons seems to explain the observed amplitude3. The low-frequency edge of the observed profile indicates that stars existed and had produced a background of Lyman-α photons by 180 million years after the Big Bang. The high-frequency edge indicates that the gas was heated to above the radiation temperature less than 100 million years later.
992 citations
TL;DR: The perovskite absorber material itself has been heavily scrutinized for being prone to degradation by water, oxygen and ultraviolet light as discussed by the authors, and it has been shown that even under the combined stresses of light (including ultraviolet light), oxygen and moisture, perovsite solar cells can retain 94% of peak efficiency despite 1,000 hours of continuous unencapsulated operation in ambient air conditions (relative humidity of 10-20%).
Abstract: Long-term device stability is the most pressing issue that impedes perovskite solar cell commercialization, given the achieved 22.7% efficiency. The perovskite absorber material itself has been heavily scrutinized for being prone to degradation by water, oxygen and ultraviolet light. To date, most reports characterize device stability in the absence of these extrinsic factors. Here we show that, even under the combined stresses of light (including ultraviolet light), oxygen and moisture, perovskite solar cells can retain 94% of peak efficiency despite 1,000 hours of continuous unencapsulated operation in ambient air conditions (relative humidity of 10–20%). Each interface and contact layer throughout the device stack plays an important role in the overall stability which, when appropriately modified, yields devices in which both the initial rapid decay (often termed burn-in) and the gradual slower decay are suppressed. This extensively modified device architecture and the understanding developed will lead towards durable long-term device performance.
684 citations
TL;DR: The near-IR-activated PEC aptasensing scheme provides a promising platform for ultrasensitive detection of other biomolecules and high reproducibility and good accuracy were achieved for analysis of human serum specimens.
Abstract: Titanium dioxide (TiO2; as a potential photosensitizer) has good photocurrent performance and chemical stability but often exhibits low utilization efficiency under ultraviolet (UV) region excitation. Herein, we devised a near-infrared light-to-UV light-mediated photoelectrochemical (PEC) aptasensing platform for the sensitive detection of carcinoembryonic antigen (CEA) based on core–shell NaYF4:Yb,Tm@TiO2 upconversion microrods by coupling with target-triggered rolling circle amplification (RCA). The upconversion microrods synthesized through the hydrothermal reaction could act as a photosensing platform to convert the near-infrared (near-IR) excitation into UV emission for generation of photoinduced electrons. The target analyte was determined on a functional magnetic bead by using the corresponding aptamers with a sandwich-type assay format. Upon target CEA introduction, a complex was first formed between capture aptamer-1-conjugated magnetic bead (Apt1-MB) and aptamer-2-primer DNA (Apt2-pDNA). Thereaf...
300 citations
TL;DR: It is shown for the first time that far-UVC efficiently inactivates airborne aerosolized viruses, with a very low dose of 2 mJ/cm2 of 222-nm light inactivating >95% of aerosolization H1N1 influenza virus.
Abstract: Airborne-mediated microbial diseases such as influenza and tuberculosis represent major public health challenges. A direct approach to prevent airborne transmission is inactivation of airborne pathogens, and the airborne antimicrobial potential of UVC ultraviolet light has long been established; however, its widespread use in public settings is limited because conventional UVC light sources are both carcinogenic and cataractogenic. By contrast, we have previously shown that far-UVC light (207–222 nm) efficiently inactivates bacteria without harm to exposed mammalian skin. This is because, due to its strong absorbance in biological materials, far-UVC light cannot penetrate even the outer (non living) layers of human skin or eye; however, because bacteria and viruses are of micrometer or smaller dimensions, far-UVC can penetrate and inactivate them. We show for the first time that far-UVC efficiently inactivates airborne aerosolized viruses, with a very low dose of 2 mJ/cm2 of 222-nm light inactivating >95% of aerosolized H1N1 influenza virus. Continuous very low dose-rate far-UVC light in indoor public locations is a promising, safe and inexpensive tool to reduce the spread of airborne-mediated microbial diseases.
256 citations
TL;DR: In this paper, a simple hydrothermal treatment process was used for the fabrication of a Ti3C2Tx (MXene) nanosheet-based hybrid photocatalyst.
255 citations
TL;DR: An inorganic-perovskite/organic four-terminal tandem solar cell based on a semitransparent inorganic CsPbBr3 perovskITE solar cell (pero-SC) as the top cell and an OSC as bottom cell is constructed, avoiding the instability problem of UV light on the bottom OSC and leading to the highest reported PCE.
Abstract: Organic solar cells (OSCs) can be unstable under ultraviolet (UV) irradiation. To address this issue and enhance the power conversion efficiency (PCE), an inorganic-perovskite/organic four-terminal tandem solar cell (TSC) based on a semitransparent inorganic CsPbBr3 perovskite solar cell (pero-SC) as the top cell and an OSC as bottom cell is constructed. The high-quality CsPbBr3 photoactive layer of the planar pero-SC is prepared with a dual-source vacuum coevaporation method, using stoichiometric precursors of CsBr and PbBr2 with a low evaporation rate. The resultant opaque planar pero-SC exhibits an ultrahigh open-circuit voltage of 1.44 V and the highest reported PCE of 7.78% for a CsPbBr3 -based planar pero-SC. Importantly, the devices show no degradation after 120 h UV light illumination. The related semitransparent pero-SC can almost completely filter UV light and well maintain photovoltaic performance; it additionally shows an extremely high average visible transmittance. When it is used to construct a TSC, the top pero-SC acting as a UV filter can utilize UV light for photoelectric conversion, avoiding the instability problem of UV light on the bottom OSC that can meet the industrial standards of UV-light stability for solar cells, and leading to the highest reported PCE of 14.03% for the inorganic-perovskite/organic TSC.
242 citations
TL;DR: In this article, the authors provide a summary of recent progress in nitrogen-doped simple/complex oxides for photocatalysis, and some useful guidelines for the future development are discussed.
233 citations
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01 Jan 2018
TL;DR: Barosa-Canovas and Canovas as mentioned in this paper used Pulsed Electric Fields (PEF) to extract juice from food plants and applied it in processing and preservation of plant foods.
Abstract: Present Status and the Future of PEF Technology, G.V. Barbosa-Canovas and D. Sepulveda Microbial Inactivation by Pulsed Electric Fields, R. Pagan, S. Condon, and J. Raso Inactivation Kinetics of Microorganisms by Pulsed Electric Fields, M. Rodrigo, A. Martinez, and D. Rodrigo Does High-Intensity Pulsed Electric Fields Induce Changes In Enzymatic Activity, Protein Conformation, and Vitamin and Flavor Stability?, O. Martin-Belloso, S. Bendicho, P. Elez-Martinez, and G. V. Barbosa-Canovas Pulsed Electric Field-Assisted Extraction of Juice from Food Plants, E. Vorobiev, A. Baset Jemai, H. Bouzrara, N. Lebovka, and M. Bazhal Application of PEF on Orange Juice Products, D. Rodrigo, F. Sampedro, A. Martinez, M. Rodrigo, and G.V. Barbosa- Canovas PEF-A Food Industry's View, H. Lelieveld Fundamentals and Applications of High Pressure Processing to Foods, J. Welti-Chanes, A. Lopez-Malo, E. Palou, D. Bermudez, J.A. Guerrero-Beltran, and G.V. Barbosa-Canovas Thermodynamic Aspects of High Hydrostatic Pressure Food Processing, G. V. Barbosa-Canovas and J. J. Rodriguez High-Pressure-Assisted Heating as a Method for Sterilizing Foods, V.Heinz and D. Knorr Freezing and Thawing of Foods Under Pressure, P.D. Sanz Starch and Other Polysaccharides Under High Pressure, F. Ferna'ndez-Martin, G. Tabilo-Munizaga, and G. V. Barbosa-Canovas Advances in Use of High Pressure to Processing and Preservation of Plant Foods, M. Pilar Cano and B. de Ancos High-Pressure Applications on Myosystems, P. Montero and M. Gomez-Guillen High-Pressure Processing of Milk and Dairy and Egg Products, B. Guamis, R. Pla, A.J. Trujillo, M. Capellas, R. Gervilla, J. Saldo, and J. Yuste Commercial High-Pressure Equipment, J. Hjelmqwist Food Irradiation-An Emerging Technology, J. H. Moy Ultraviolet Light and Food Preservation, A. Lopez-Malo and E. Palou Microbial Inactivation by Ultrasound, S. Condon, J. Raso, and R. Pagan Use of Magnetic Fields as a Nonthermal Technology, G. V. Barbosa-Canovas, B. G. Swanson, M. Fernanda San Martin G., and F. Harte Nonthermal Technologies in Combination with Other Preservation Factors, J. Raso, R. Pagan, and S. Condon Sous Vide/Freezing Technology for Ready Meals, F.S. Tansey and T.R. Gormley Advances in Ohmic Heating and Moderate Electric Field (MEF) Processing, S. K. Sastry Radio-Frequency Heating in Food Processing, J. Tang, Y. Wang, and T.V. Chow Ting Chan Current State of Microwave Applications to Food Processing, P. Fito, A. Chiralt, and M. Eugenia Martin Supercritical Fluid Extraction: An Alternative to Isolating Natural Food Preservatives, G. Reglero, F. Javier Senorans, and E. Ibanez Modeling Systems and Impact on Food Microbiology, G. Betts and L. Everis Predictive Microbiology and Role in Food Safety Systems, A. Martinez, M. Rodrigo, D. Rodrigo, P. Ruiz, A. Martinez, and Ma. Jose' Ocio Experimental Protocols for Modeling the Response of Microbial Populations Exposed to Emerging Technologies: Some Points of Concern, S. M. Alzamora, S. Guerrero, P. E. Viollaz, and J. Welti-Chanes Application of Artiocial Intelligence to Predictive Microbiology, R. M. Garcia-Gimeno, C. Hervas- Martinez, and G. Zurera-Cosano Growth/No-Growth Interface Modeling and Emerging Technologies, E. Palou and A. Lopez-Malo Calculating Microbial Inactivation During Heat Treatments Without D and Z Values, M. Peleg Safety and Quality in the Food Industry, M. S. Tapia, I. Arispe, and A. Martinez Index
217 citations
TL;DR: A new class of active thermal surfaces capable of efficient real-time electrical-control of thermal emission over the full infrared (IR) spectrum without changing the temperature of the surface is reported.
Abstract: In nature, adaptive coloration has been effectively utilized for concealment and signaling. Various biological mechanisms have evolved to tune the reflectivity for visible and ultraviolet light. These examples inspire many artificial systems for mimicking adaptive coloration to match the visual appearance to their surroundings. Thermal camouflage, however, has been an outstanding challenge which requires an ability to control the emitted thermal radiation from the surface. Here we report a new class of active thermal surfaces capable of efficient real-time electrical-control of thermal emission over the full infrared (IR) spectrum without changing the temperature of the surface. Our approach relies on electro-modulation of IR absorptivity and emissivity of multilayer graphene via reversible intercalation of nonvolatile ionic liquids. The demonstrated devices are light (30 g/m2), thin (<50 μm), and ultraflexible, which can conformably coat their environment. In addition, by combining active thermal surfaces with a feedback mechanism, we demonstrate realization of an adaptive thermal camouflage system which can reconfigure its thermal appearance and blend itself with the varying thermal background in a few seconds. Furthermore, we show that these devices can disguise hot objects as cold and cold ones as hot in a thermal imaging system. We anticipate that, the electrical control of thermal radiation would impact on a variety of new technologies ranging from adaptive IR optics to heat management for outer space applications.
209 citations
TL;DR: In this paper, a laboratory protocol that simulates the exposure of plastic floating in the marine environment to ultraviolet light (UV) and nontarget analysis to identify degradation products of plastic polymers in water was developed.
Abstract: Buoyant plastic in the marine environment is exposed to sunlight, oxidants, and physical stress, which may lead to degradation of the plastic polymer and the release of compounds that are potentially hazardous. We report the development of a laboratory protocol that simulates the exposure of plastic floating in the marine environment to ultraviolet light (UV) and nontarget analysis to identify degradation products of plastic polymers in water. Plastic pellets [polyethylene, polypropylene, polystyrene, and poly(ethylene terephthalate)] suspended in water were exposed to a UV light source for 5 days. Organic chemicals in the water were concentrated by solid phase extraction and then analyzed by ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry using a nontarget approach with a C18 LC column coupled to a Q Exactive Orbitrap HF mass spectrometer. We designed a data analysis scheme to identify chemicals that are likely chain scission products from degradation of the plas...
TL;DR: In this article, the authors explore the universality of electronic characteristics and photocatalyst applications of two-dimensional Janus transition metal dichalcogenides and find that the induced dipole moment, vibrational frequency, Rashba parameters, and direct-indirect band transition of monolayer $MXY$ are deeply associated with the atomic radius and electronegativity differences of chalinogen $X and $Y$ elements.
Abstract: Due to mirror symmetry breaking, two-dimensional Janus transition metal dichalcogenides $MXY$ ($M=\text{Mo,W}$; $X,Y=\text{S,Se,Te}$) present charming electronic properties. However, there have not been many related studies as of yet, and the intrinsic physical pictures are unclear. Here, we use first-principles calculations to explore the universality of electronic characteristics and photocatalyst applications of Janus $MXY$, finding that the induced dipole moment, vibrational frequency, Rashba parameters, and direct-indirect band transition of monolayer $MXY$ are deeply associated with the atomic radius and electronegativity differences of chalcogen $X$ and $Y$ elements. The internal electric field renders Janus $MXY$ the ideal photocatalysts. Moreover, the stacking-dependent on/off switch of the dipole moment further confirms that asymmetric Janus $MXY$ serves as a promising candidate for highly efficient photocatalysts within a broad range from infrared, visible, to ultraviolet light.
TL;DR: In this article, a van der Waals-based inter-layer heterostructure of a blue phosphorene (BlueP)/BSe interlayer interlayer structure has been shown to be a potential photocatalyst for water splitting under different pH conditions.
Abstract: Constructing van der Waals heterostructures can enhance two-dimensional (2D) materials with desired properties and greatly extend the applications of the original materials. On the basis of density functional theory calculations, we verify that a blue phosphorene (BlueP)/BSe inter-layer heterostructure possesses an indirect gap and intrinsic type-II band alignment. In particular, this heterostructure is found to be a potential photocatalyst for water splitting under different pH conditions and exhibits enhanced optical properties in the visible and ultraviolet light zones. Besides, we confirm that the band gap, band edge position, and optical absorption of the BlueP/BSe heterostructure can be tailored by biaxial strain. And the tensile strain increases the optical absorption significantly over the entire energy range of visible light, which can increase the efficiency of solar energy conversion. Furthermore, we determine that adjusting the number of sublayers is another effective method to modulate the band gaps and band alignments of heterostructures. Our studies provide a promising route to design new BlueP-based vdW heterostructures and explore their potential applications in electronic and optoelectronic devices.
TL;DR: This review predominantly concentrates on DNA damage induced by the following carcinogens: polycyclic aromatic hydrocarbons, heterocyclic aromatic amines, mycotoxins, ultraviolet light, ionising radiation, aristolochic acid, nitrosamines and particulate matter.
Abstract: Humans are variously and continuously exposed to a wide range of different DNA-damaging agents, some of which are classed as carcinogens. DNA damage can arise from exposure to exogenous agents, but damage from endogenous processes is probably far more prevalent. That said, epidemiological studies of migrant populations from regions of low cancer risk to high cancer risk countries point to a role for environmental and/or lifestyle factors playing a pivotal part in cancer aetiology. One might reasonably surmise from this that carcinogens found in our environment or diet are culpable. Exposure to carcinogens is associated with various forms of DNA damage such as single-stand breaks, double-strand breaks, covalently bound chemical DNA adducts, oxidative-induced lesions and DNA–DNA or DNA–protein cross-links. This review predominantly concentrates on DNA damage induced by the following carcinogens: polycyclic aromatic hydrocarbons, heterocyclic aromatic amines, mycotoxins, ultraviolet light, ionising radiation, aristolochic acid, nitrosamines and particulate matter. Additionally, we allude to some of the cancer types where there is molecular epidemiological evidence that these agents are aetiological risk factors. The complex role that carcinogens play in the pathophysiology of cancer development remains obscure, but DNA damage remains pivotal to this process.
TL;DR: In this article, a large-area tandem LSC based on nearly reabsorption-free carbon dots (C-dots) and inorganic mixed-halide perovskite quantum dots (QDs) was designed for optimal solar-spectrum splitting.
TL;DR: The results show that Se doping significantly improves the photocatalytic activity of TiO2 and 13.63 at.% Se-dopedTiO2 has the best performance.
Abstract: Anatase TiO2 is a typical photocatalyst, and its excellent performance is limited in ultraviolet light range due to its wide band gap of 3.2 eV. A series of Se-doped TiO2 nanoparticles in anatase structure with various Se concentrations up to 17.1 at.% were prepared using sol-gel method. The doped Se ions are confirmed to be mainly in the valence state of + 4, which provides extra electronic states in the band gap of TiO2. The band gap is effectively narrowed with the smallest gap energy of 2.17 eV, and the photocatalytic activity is effectively improved due to the extended absorption range. The photocatalytic activity was evaluated by the degradation of Rhodamine B (RhB) in aqueous solution under visible light irradiation. The results show that Se doping significantly improves the photocatalytic activity of TiO2 and 13.63 at.% Se-doped TiO2 has the best performance.
TL;DR: 3D bioprinting techniques are rendered as productive on‐demand options for the creation of skin models available for therapeutic or research use by producing engineered ephelides in biomimetic skin.
Abstract: This study reports a three-dimensional (3D) bioprinting technique that is capable of producing a full-thickness skin model containing pigmentation. Multiple layers of fibroblast (FB)-containing collagen hydrogel precursor were printed and crosslinked through neutralization using sodium bicarbonate, constituting the dermal layer. Melanocytes (MCs) and keratinocytes (KCs) were sequentially printed on top of the dermal layer to induce skin pigmentation upon subsequent air-liquid interface culture. Histological analysis was performed not only to confirm the formation of distinct skin layers, but also to identify the presence of pigmentation. The bioprinted skin structure showed the dermal and epidermal layers as well as the terminal differentiation of the KC that formed the stratum corneum. Moreover, the MC-containing epidermal layer showed freckle-like pigmentations at the dermal-epidermal junction, without the use of external ultraviolet light or chemical stimuli. The presented method offers the capability of producing engineered ephelides in biomimetic skin, thus rendering 3D bioprinting techniques as productive on-demand options for the creation of skin models available for therapeutic or research use.
TL;DR: In this paper, an experimental study was conducted at laboratory scale with the aim of investigating the efficiency of a new magnetic nanocatalyst (FeNi3/SiO2/CuS) for degradation of tetracycline-the second common group of antibiotics in terms of production and consumption in the world-in the presence of ultraviolet light in aqueous solutions.
TL;DR: It is suggested that antioxidant supplementation may be helpful in people exposed to excessive production of ROS in the oral cavity system, and recognition of the exogenous sources of ROS and limitation of exposure to the ROS generating factors can be one of the prophylactic measures preventing oral and systemic diseases.
TL;DR: The PA-CA hydrogel possessed a benign biocompatibility on Escherichia coli and foxtail millet, showing a high biosafety, and provides a promising approach to pH-responsively controlled release chlorpyrifos.
Abstract: In this work, a pH-responsively controlled-release chlorpyrifos (PRCRC) was developed using a nanosystem consisting of chlorpyrifos (CPF), polydopamine (PDA), attapulgite (ATP), and calcium alginate (CA). Therein, CPF was adsorbed in the nanonetwork-structured PDA-modified ATP (PA) to obtain CPF-PA through hydrogen bonds and electrostatic attraction. Subsequently, CPF-PA combined with CA to form porous CPF-PA-CA hydrogel spheres (actually PRCRC) through cross-linking reaction, wherein PA acted as the skeleton. PRCRC spheres tended to collapse in alkaline solution and promoted the release of CPF, thus displayed a good pH-responsively controlled release performance, which was proved by the control efficacy test on grubs. Besides, the system could effectively protect CPF molecules from degradation under ultraviolet light. Importantly, the PA-CA hydrogel possessed a benign biocompatibility on Escherichia coli and foxtail millet, showing a high biosafety. Therefore, this work provides a promising approach to i...
TL;DR: A facile approach is developed to synthesize black TiO2 nanoparticles with significantly improved light absorption in the visible and infrared regions and shows that oxygen vacancies are the major factors responsible for black coloration.
Abstract: Black TiO2 has triggered worldwide research interest due to its excellent photocatalytic properties. However, the understanding of its structure–property relationships and a more effective, facile and versatile method to produce it remain great challenges. We have developed a facile approach to synthesize black TiO2 nanoparticles with significantly improved light absorption in the visible and infrared regions. The experimental results show that oxygen vacancies are the major factors responsible for black coloration. More importantly, our black TiO2 nanoparticles have no Ti3+ ions. These oxygen vacancies could introduce localized states in the bandgap and act as trap centers, significantly decreasing the electron–hole recombination. The photocatalytic decomposition of both rhodamine B and methylene blue demonstrated that, under ultraviolet light irradiation, better photocatalytic performance is achieved with our black TiO2 nanoparticles than with commercial TiO2 nanoparticles.
TL;DR: In this article, the authors demonstrated a facile and environmental friendly method to enhance hydrogen production by introducing defects of O vacancy and Ti3+ in surface and bulk TiO2 (B) nanosheets through the ambient-temperature plasma engraving treatment.
Abstract: As for practical application, ultrathin two-dimension (2D) materials have exhibited high performances in photocatalysis, electrocatalysis, and supercapacitors. Usually, when used 2D TiO2 (B) nanosheet as a photocatalyst, it absorbs only ultraviolet light, and several approaches have been taken to narrow the band gap of TiO2. Thus, we demonstrated a facile and environmental friendly method to enhancing hydrogen production by introducing defects of O vacancy and Ti3+ in surface and bulk TiO2 (B) nanosheets through the ambient-temperature plasma engraving treatment. After plasma treatment, the band gap of the 2D TiO2 (B) nanosheets decreased from approximately 3.13 eV–2.88 eV and the H2 evolution performance of them is almost twice as high as pristine TiO2 (B) nanosheets under AM 1.5 illumination. The enhanced photocatalytic performances arise from the doping defect of O vacancy and Ti3+, narrowing the energy band gap and increasing more active sites of material surface with function of plasma engraving. The findings in this work may provide a new approach for improving the photocatalytic activities of other metal oxides.
TL;DR: This work provides new opportunities of building next-generation solar cells with significantly simplified processes and reduced production costs by achieving an efficiency as high as 4.1% and improved stability upon interfacial modification by graphene quantum dots and CsPbBrI2 quantum dots.
Abstract: Perovskite solar cells with cost-effectiveness, high power conversion efficiency, and improved stability are promising solutions to the energy crisis and environmental pollution. However, a wide-bandgap inorganic-semiconductor electron-transporting layer such as TiO2 can harvest ultraviolet light to photodegrade perovskite halides, and the high cost of a state-of-the-art hole-transporting layer is an economic burden for commercialization. Here, the building of a simplified cesium lead bromide (CsPbBr3 ) perovskite solar cell with fluorine-doped tin oxide (FTO)/CsPbBr3 /carbon architecture by a multistep solution-processed deposition technology is demonstrated, achieving an efficiency as high as 4.1% and improved stability upon interfacial modification by graphene quantum dots and CsPbBrI2 quantum dots. This work provides new opportunities of building next-generation solar cells with significantly simplified processes and reduced production costs.
TL;DR: In this article, a multilayer-structure Fe@γ-Fe2 O3 @H-TiO2 nanocomposites (NCs) with multi-layer structure are synthesized by one-step hydrogen reduction, which show remarkably improved magnetic and photoconversion effects as a promising generalists for photocatalysis, bioimaging, and photothermal therapy.
Abstract: Titanium dioxide (TiO2 ) has been widely investigated and used in many areas due to its high refractive index and ultraviolet light absorption, but the lack of absorption in the visible-near infrared (Vis-NIR) region limits its application. Herein, multifunctional Fe@γ-Fe2 O3 @H-TiO2 nanocomposites (NCs) with multilayer-structure are synthesized by one-step hydrogen reduction, which show remarkably improved magnetic and photoconversion effects as a promising generalists for photocatalysis, bioimaging, and photothermal therapy (PTT). Hydrogenation is used to turn white TiO2 in to hydrogenated TiO2 (H-TiO2 ), thus improving the absorption in the Vis-NIR region. Based on the excellent solar-driven photocatalytic activities of the H-TiO2 shell, the Fe@γ-Fe2 O3 magnetic core is introduced to make it convenient for separating and recovering the catalytic agents. More importantly, Fe@γ-Fe2 O3 @H-TiO2 NCs show enhanced photothermal conversion efficiency due to more circuit loops for electron transitions between H-TiO2 and γ-Fe2 O3 , and the electronic structures of Fe@γ-Fe2 O3 @H-TiO2 NCs are calculated using the Vienna ab initio simulation package based on the density functional theory to account for the results. The reported core-shell NCs can serve as an NIR-responsive photothermal agent for magnetic-targeted photothermal therapy and as a multimodal imaging probe for cancer including infrared photothermal imaging, magnetic resonance imaging, and photoacoustic imaging.
TL;DR: It is demonstrated that the swarming of DNA-functionalized microtubules propelled by surface-adhered kinesin motors can be programmed and reversibly regulated by DNA signals and switching between solitary and swarm behaviour by employing photoresponsive DNA strands.
Abstract: In nature, swarming behavior has evolved repeatedly among motile organisms because it confers a variety of beneficial emergent properties. These include improved information gathering, protection from predators, and resource utilization. Some organisms, e.g., locusts, switch between solitary and swarm behavior in response to external stimuli. Aspects of swarming behavior have been demonstrated for motile supramolecular systems composed of biomolecular motors and cytoskeletal filaments, where cross-linkers induce large scale organization. The capabilities of such supramolecular systems may be further extended if the swarming behavior can be programmed and controlled. Here, we demonstrate that the swarming of DNA-functionalized microtubules (MTs) propelled by surface-adhered kinesin motors can be programmed and reversibly regulated by DNA signals. Emergent swarm behavior, such as translational and circular motion, can be selected by tuning the MT stiffness. Photoresponsive DNA containing azobenzene groups enables switching between solitary and swarm behavior in response to stimulation with visible or ultraviolet light.
TL;DR: This review summarizes current knowledge of atmospheric aggressors, including UVA, UVB, visible light, infrared radiation (IR), and ozone on skin damage, and proposes new avenues for future research in the prevention and treatment of premature skin aging caused by such atmospheric factors.
Abstract: Cutaneous aging is a complex biological process consisting of 2 elements: intrinsic aging, which is primarily determined by genetics, and extrinsic aging, which is largely caused by atmospheric factors, such as exposure to sunlight and air pollution, and lifestyle choices, such as diet and smoking. The role of the solar spectrum, comprised of ultraviolet light, specifically UVB (290-320 nm) and UVA (320-400) in causing skin damage, including skin cancers, has been well documented. In recent years, the contribution of visible light (400-700 nm) and infrared radiation (above 800 nm) in causing skin damage, similar to the photodamage caused by UV light, is also being elucidated. In addition, other atmospheric factors such as air pollution (smog, ozone, particulate matter, etc.) have been implicated in premature skin aging. The skin damage caused by environmental exposure is largely attributable to a complex cascade of reactions inside the skin initiated by the generation of reactive oxygen species (ROS), which causes oxidative damage to cellular components such as proteins, lipids, and nucleic acids. These damaged skin cells initiate inflammatory responses leading to the eventual damage manifested in chronically exposed skin. Novel therapeutic strategies to combat ROS species generation are being developed to prevent the skin damage caused by atmospheric factors. In addition to protecting skin from solar radiation using sunscreens, other approaches using topically applied ingredients, particularly antioxidants that penetrate the skin and protect the skin from within, have also been well documented. This review summarizes current knowledge of atmospheric aggressors, including UVA, UVB, visible light, infrared radiation (IR), and ozone on skin damage, and proposes new avenues for future research in the prevention and treatment of premature skin aging caused by such atmospheric factors. New therapeutic modalities currently being developed are also discussed.
TL;DR: The ZnWO4 nanocrystals obtained at 160 °C exhibited excellent photodegradation of Rhodamine under ultraviolet light irradiation, which was found to be related to the surface energy and the types of clusters formed on the surface of the catalyst.
Abstract: The present joint experimental and theoretical work provides in-depth understanding on the morphology and structural, electronic, and optical properties of ZnWO4 nanocrystals. Monoclinic ZnWO4 nanocrystals were prepared at three different temperatures (140, 150, and 160 °C) by a microwave hydrothermal method. Then, the samples were investigated by X-ray diffraction with Rietveld refinement analysis, field-emission scanning electron microscopy, transmission electronic microscopy, micro-Raman and Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, and photoluminescence measurements. First-principles theoretical calculations within the framework of density functional theory were employed to provide information at the atomic level. The band structure diagram, density of states, Raman and infrared spectra were calculated to understand the effect of structural order-disorder on the properties of ZnWO4. The effects of the synthesis temperature on the above properties were rationalized. The band structure revealed direct allowed transitions between the VB and CB and the experimental results in the ultraviolet-visible region were consistent with the theoretical results. Moreover, the surface calculations allowed the association of the surface energy stabilization with the temperature used in the synthesis of the ZnWO4 nanocrystals. The photoluminescence properties of the ZnWO4 nanocrystals prepared at 140, 150, and 160 °C were attributed to oxygen vacancies in the [WO6] and [ZnO6] clusters, causing a red shift of the spectra. The ZnWO4 nanocrystals obtained at 160 °C exhibited excellent photodegradation of Rhodamine under ultraviolet light irradiation, which was found to be related to the surface energy and the types of clusters formed on the surface of the catalyst.
10 Jan 2018
TL;DR: The use of homogeneous photodegradation to treat contaminated water dates back to the early 1970s as mentioned in this paper, and the range of contaminated waters that may be treated with homogeneous photolysis systems is quite broad, including drinking water, groundwater, industrial process water, marine tank ballast water, process water in offshore drilling rigs, etc.
Abstract: This chapter focuses on the processes that involve homogeneous photolysis. It also focuses on applications in water treatment, since this area is much more developed than the photochemical treatment of contaminated air. The use of homogeneous photodegradation to treat contaminated water dates back to the early 1970s. The range of contaminated waters that may be treated with homogeneous photolysis systems is quite broad, including drinking water, groundwater, industrial process water, marine tank ballast water, process water in offshore drilling rigs, etc. Only the homogeneous photolysis processes have been fully implemented commercially, and even in that case only a small fraction of potential sites are employing these processes. The use of ultraviolet light for the photodegradation of pollutants in water can be classified into three principal areas: photooxidation, photoreduction, and direct photodegradation. In order to maximize the rate of reaction, there must be a good wavelength overlap between the emission of the lamp and the absorbance of the absorbing species.
TL;DR: Recent progress in UCNP development has generated the possibility to employ a wide variety of NIR excitation sources in PDT, and use of UCNPs enables concurrent strategies for loading, targeting, and controlling the release of additional drugs.
Abstract: Photodynamic therapy (PDT) is a minimally invasive cancer modality that combines a photosensitizer (PS), light, and oxygen. Introduction of new nanotechnologies holds potential to improve PDT performance. Upconversion nanoparticles (UCNPs) offer potentially advantageous benefits for PDT, attributed to their distinct photon upconverting feature. The ability to convert near-infrared (NIR) light into visible or even ultraviolet light via UCNPs allows for the activation of nearby PS agents to produce singlet oxygen, as most PS agents absorb visible and ultraviolet light. The use of a longer NIR wavelength permits light to penetrate deeper into tissue, and thus PDT of a deeper tissue can be effectively achieved with the incorporation of UCNPs. Recent progress in UCNP development has generated the possibility to employ a wide variety of NIR excitation sources in PDT. Use of UCNPs enables concurrent strategies for loading, targeting, and controlling the release of additional drugs. In this review article, recent progress in the development of UCNPs for PDT applications is summarized.
TL;DR: In this article, three new luminescent metal-organic frameworks (MOFs) were designed and successfully prepared via a solvothermal reaction using V-shaped rigid multicarboxylate 2,4-di(3′,5′-dicaroxylphenyl)benzoic acid (H5L) and Cd(II) salts in various solvent systems.
Abstract: Herein, three new luminescent metal–organic frameworks (MOFs), namely {[Cd4(H3L)4(H2O)12]·2.5H2O}n (1), {[Cd(L)]·2.5H2O·3[H2N(Me)2]}n (2), and {[Cd2(L)(DMA)]·[H2N(Me)2]}n (3), were designed and successfully prepared via a solvothermal reaction using V-shaped rigid multicarboxylate 2,4-di(3′,5′-dicarboxylphenyl)benzoic acid (H5L) and Cd(II) salts in various solvent systems. The structural analyses indicated that the H3L2−/L5− ligands took three different coordination fashions in 1–3; this resulted in a diversity of targeted MOFs. The solid-state luminescence properties of three MOFs were studied under ultraviolet light irradiation at ambient temperature, and 3 showed a high selectivity and sensitivity for nitrobenzene and Fe3+ because of the quenching effect. Thus, it could be a potential crystalline material for detecting these substances. The mechanisms of the quenching effect and sensing properties of 3 have been discussed in detail.