Showing papers on "Ultraviolet light published in 2016"

PD-1 Blockade with Pembrolizumab in Advanced Merkel-Cell Carcinoma

Abstract: BackgroundMerkel-cell carcinoma is an aggressive skin cancer that is linked to exposure to ultraviolet light and the Merkel-cell polyomavirus (MCPyV). Advanced Merkel-cell carcinoma often responds to chemotherapy, but responses are transient. Blocking the programmed death 1 (PD-1) immune inhibitory pathway is of interest, because these tumors often express PD-L1, and MCPyV-specific T cells express PD-1. MethodsIn this multicenter, phase 2, noncontrolled study, we assigned adults with advanced Merkel-cell carcinoma who had received no previous systemic therapy to receive pembrolizumab (anti–PD-1) at a dose of 2 mg per kilogram of body weight every 3 weeks. The primary end point was the objective response rate according to Response Evaluation Criteria in Solid Tumors, version 1.1. Efficacy was correlated with tumor viral status, as assessed by serologic and immunohistochemical testing. ResultsA total of 26 patients received at least one dose of pembrolizumab. The objective response rate among the 25 patient...

Additive manufacturing of polymer-derived ceramics

Abstract: The extremely high melting point of many ceramics adds challenges to additive manufacturing as compared with metals and polymers. Because ceramics cannot be cast or machined easily, three-dimensional (3D) printing enables a big leap in geometrical flexibility. We report preceramic monomers that are cured with ultraviolet light in a stereolithography 3D printer or through a patterned mask, forming 3D polymer structures that can have complex shape and cellular architecture. These polymer structures can be pyrolyzed to a ceramic with uniform shrinkage and virtually no porosity. Silicon oxycarbide microlattice and honeycomb cellular materials fabricated with this approach exhibit higher strength than ceramic foams of similar density. Additive manufacturing of such materials is of interest for propulsion components, thermal protection systems, porous burners, microelectromechanical systems, and electronic device packaging.

Improving efficiency and stability of perovskite solar cells with photocurable fluoropolymers.

Abstract: Organometal halide perovskite solar cells have demonstrated high conversion efficiency but poor long-term stability against ultraviolet irradiation and water. We show that rapid light-induced free-radical polymerization at ambient temperature produces multifunctional fluorinated photopolymer coatings that confer luminescent and easy-cleaning features on the front side of the devices, while concurrently forming a strongly hydrophobic barrier toward environmental moisture on the back contact side. The luminescent photopolymers re-emit ultraviolet light in the visible range, boosting perovskite solar cells efficiency to nearly 19% under standard illumination. Coated devices reproducibly retain their full functional performance during prolonged operation, even after a series of severe aging tests carried out for more than 6 months.

Toxicopathological Effects of the Sunscreen UV Filter, Oxybenzone (Benzophenone-3), on Coral Planulae and Cultured Primary Cells and Its Environmental Contamination in Hawaii and the U.S. Virgin Islands

Abstract: Benzophenone-3 (BP-3; oxybenzone) is an ingredient in sunscreen lotions and personal-care products that protects against the damaging effects of ultraviolet light. Oxybenzone is an emerging contaminant of concern in marine environments—produced by swimmers and municipal, residential, and boat/ship wastewater discharges. We examined the effects of oxybenzone on the larval form (planula) of the coral Stylophora pistillata, as well as its toxicity in vitro to coral cells from this and six other coral species. Oxybenzone is a photo-toxicant; adverse effects are exacerbated in the light. Whether in darkness or light, oxybenzone transformed planulae from a motile state to a deformed, sessile condition. Planulae exhibited an increasing rate of coral bleaching in response to increasing concentrations of oxybenzone. Oxybenzone is a genotoxicant to corals, exhibiting a positive relationship between DNA-AP lesions and increasing oxybenzone concentrations. Oxybenzone is a skeletal endocrine disruptor; it induced ossification of the planula, encasing the entire planula in its own skeleton. The LC50 of planulae exposed to oxybenzone in the light for an 8- and 24-h exposure was 3.1 mg/L and 139 µg/L, respectively. The LC50s for oxybenzone in darkness for the same time points were 16.8 mg/L and 779 µg/L. Deformity EC20 levels (24 h) of planulae exposed to oxybenzone were 6.5 µg/L in the light and 10 µg/L in darkness. Coral cell LC50s (4 h, in the light) for 7 different coral species ranges from 8 to 340 µg/L, whereas LC20s (4 h, in the light) for the same species ranges from 0.062 to 8 µg/L. Coral reef contamination of oxybenzone in the U.S. Virgin Islands ranged from 75 µg/L to 1.4 mg/L, whereas Hawaiian sites were contaminated between 0.8 and 19.2 µg/L. Oxybenzone poses a hazard to coral reef conservation and threatens the resiliency of coral reefs to climate change.

Highly Efficient Light-Driven TiO2–Au Janus Micromotors

Abstract: A highly efficient light-driven photocatalytic TiO2–Au Janus micromotor with wireless steering and velocity control is described. Unlike chemically propelled micromotors which commonly require the addition of surfactants or toxic chemical fuels, the fuel-free Janus micromotor (diameter ∼1.0 μm) can be powered in pure water under an extremely low ultraviolet light intensity (2.5 × 10–3 W/cm2), and with 40 × 10–3 W/cm2, they can reach a high speed of 25 body length/s, which is comparable to common Pt-based chemically induced self-electrophoretic Janus micromotors. The photocatalytic propulsion can be switched on and off by incident light modulation. In addition, the speed of the photocatalytic TiO2–Au Janus micromotor can be accelerated by increasing the light intensity or by adding low concentrations of chemical fuel H2O2 (i.e., 0.1%). The attractive fuel-free propulsion performance, fast movement triggering response, low light energy requirement, and precise motion control of the TiO2–Au Janus photocataly...

Photo-degradation of organic dyes: simple chemical synthesis of Ni(OH)2 nanoparticles, Ni/Ni(OH)2 and Ni/NiO magnetic nanocomposites

Abstract: In this work Ni, Ni(OH)2, NiO nanoparticles as well as Ni/Ni(OH)2 and Ni/NiO nanocomposites were synthesized via a simple chemical precipitation method in aqueous solution. The prepared products were characterized by X-ray diffraction pattern (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) spectroscopy. Alternating gradient force magnetometer (AGFM) illustrated ferro-magnetic behaviour of Ni nanoparticles as well as Ni/Ni(OH)2 and Ni/NiO nanocomposites. The photocatalytic behaviour of Ni–NiO nanocomposites was evaluated using the degradation of organic dyes under ultraviolet light irradiation. The results show that Ni–NiO nanocomposites have applicable magnetic and photocatalytic performance.

A single Eu2+-activated high-color-rendering oxychloride white-light phosphor for white-light-emitting diodes.

Abstract: Single-phased, high-color-rendering index (CRI) white-light phosphors are emerging as potential phosphor-converted white-light-emitting diodes (WLEDs) and as an alternative to blends of tricolor phosphors. However, it is a challenge to create a high CRI white light from a single-doped activator. Here, we present a high CRI (Ra = 91) white-light phosphor, Sr5(PO4)3-x(BO3)xCl:Eu2+, composed of Sr5(PO4)3Cl as the beginning member and Sr5(BO3)3Cl as the end member. This work utilized the solid-solution method, and tunable Eu2+ emission was achieved. Color-tunable Eu2+ emissions in response to structural variation were observed in Sr5(PO4)3-x(BO3)xCl solid solutions. This was further confirmed using X-ray Rietveld refinement, electron paramagnetic resonance spectroscopy, and in the photoluminescence spectra. The color-tunable emissions included the white light that originated from the combination of the blue emission of Sr5(PO4)3Cl:Eu2+ and an induced Eu2+ yellow emission at approximately 550 nm in the solid solution. Importantly, the white-light phosphors showed a greater R9 = 90.2 under excitation at 365 nm. This result has rarely been reported in the literature and is greater than that of (R9 = 14.3) commercial Y3Al5O12:Ce3+-based WLEDs. These findings demonstrate the great potential of Sr5(PO4)3-x(BO3)xCl:0.04Eu2+ as a white-light phosphor for near-UV phosphor-converted WLEDs. These results also provide a shortcut for developing a high CRI white-light phosphor from a single Eu2+-doped compound. A white light-emitting diode with a very high colour rendering index is made using a phosphor based on a europium-doped oxychloride material. A team of scientists from China, Switzerland and the USA investigated the white-light phosphor Sr5(PO4)3−x(BO3)xCl:Eu2+. Its structural and electronic properties were characterized by X-ray diffraction analysis, photoluminescence spectroscopy, and fluorescence decay analysis of the phosphor. When excited by ultraviolet light (365 nanometres) from a light-emitting diode, the phosphor emitted broadband photoluminescence with peaks in the blue (446 nanometres) and yellow (550 nanometres) regions. These emission characteristics resulted in high-quality white light with a very high colour rendering index that was significantly better than those of existing commercial white light-emitting diodes based on the phosphor YAG:Ce3+, indicating the potential of this new phosphor.

Perfluorooctanoic Acid Degradation Using UV–Persulfate Process: Modeling of the Degradation and Chlorate Formation

Abstract: In this study, we investigated the destruction and by-product formation of perfluorooctanoic acid (PFOA) using ultraviolet light and persulfate (UV–PS). Additionally, we developed a first-principles kinetic model to simulate both PFOA destruction and by-product and chlorate (ClO3–) formation in ultrapure water (UW), surface water (SW), and wastewater (WW). PFOA degradation was significantly suppressed in the presence of chloride and carbonate species and did not occur until all the chloride was converted to ClO3– in UW and for low DOC concentrations in SW. The model was able to simulate the PS decay, pH changes, radical concentrations, and ClO3– formation for UW and SW. However, our model was unable to simulate PFOA degradation well in WW, possibly from PS activation by NOM, which in turn produced sulfate radicals.

Modern technologies for improving cleaning and disinfection of environmental surfaces in hospitals.

Abstract: Experts agree that careful cleaning and disinfection of environmental surfaces are essential elements of effective infection prevention programs. However, traditional manual cleaning and disinfection practices in hospitals are often suboptimal. This is often due in part to a variety of personnel issues that many Environmental Services departments encounter. Failure to follow manufacturer’s recommendations for disinfectant use and lack of antimicrobial activity of some disinfectants against healthcare-associated pathogens may also affect the efficacy of disinfection practices. Improved hydrogen peroxide-based liquid surface disinfectants and a combination product containing peracetic acid and hydrogen peroxide are effective alternatives to disinfectants currently in widespread use, and electrolyzed water (hypochlorous acid) and cold atmospheric pressure plasma show potential for use in hospitals. Creating “self-disinfecting” surfaces by coating medical equipment with metals such as copper or silver, or applying liquid compounds that have persistent antimicrobial activity surfaces are additional strategies that require further investigation. Newer “no-touch” (automated) decontamination technologies include aerosol and vaporized hydrogen peroxide, mobile devices that emit continuous ultraviolet (UV-C) light, a pulsed-xenon UV light system, and use of high-intensity narrow-spectrum (405 nm) light. These “no-touch” technologies have been shown to reduce bacterial contamination of surfaces. A micro-condensation hydrogen peroxide system has been associated in multiple studies with reductions in healthcare-associated colonization or infection, while there is more limited evidence of infection reduction by the pulsed-xenon system. A recently completed prospective, randomized controlled trial of continuous UV-C light should help determine the extent to which this technology can reduce healthcare-associated colonization and infections. In conclusion, continued efforts to improve traditional manual disinfection of surfaces are needed. In addition, Environmental Services departments should consider the use of newer disinfectants and no-touch decontamination technologies to improve disinfection of surfaces in healthcare.

Printed multifunctional flexible device with an integrated motion sensor for health care monitoring.

Abstract: Real-time health care monitoring may enable prediction and prevention of disease or improve treatment by diagnosing illnesses in the early stages. Wearable, comfortable, sensing devices are required to allow continuous monitoring of a person's health; other important considerations for this technology are device flexibility, low-cost components and processing, and multifunctionality. To address these criteria, we present a flexible, multifunctional printed health care sensor equipped with a three-axis acceleration sensor to monitor physical movement and motion. Because the device is designed to be attached directly onto the skin, it has a modular design with two detachable components: One device component is nondisposable, whereas the other one is disposable and designed to be worn in contact with the skin. The design of this disposable sensing sheet takes into account hygiene concerns and low-cost materials and fabrication methods as well as features integrated, printed sensors to monitor for temperature, acceleration, electrocardiograms, and a kirigami structure, which allows for stretching on skin. The reusable component of the device contains more expensive device components, features an ultraviolet light sensor that is controlled by carbon nanotube thin-film transistors, and has a mechanically flexible and stable liquid metal contact for connection to the disposable sensing sheet. After characterizing the electrical properties of the transistors and flexible sensors, we demonstrate a proof-of-concept device that is capable of health care monitoring combined with detection of physical activity, showing that this device provides an excellent platform for the development of commercially viable, wearable health care monitors.

Progress in Black Titania: A New Material for Advanced Photocatalysis

Abstract: The photocatalytic activity of TiO2 has aroused a broad range of research effort since 1972. Although TiO2 has a very high efficiency in utilizing ultraviolet light, its overall solar activity is very limited due to its wide bandgap (≈3.0−3.2 eV). This is a bottleneck for TiO2 to be applied in the areas ranging from visible-light photocatalysis and photovoltaics to photo-electrochemistry and sensors. Recently, the emergence of black TiO2 nanomaterial has triggered world-wide research interest, because of its substantially enhanced solar absorption and the improved photocatalytic activities. Here, a variety of synthetic strategies of black TiO2 are outlined, and the structural and chemical features, band structures and electronic properties of the black TiO2 nanomaterials are described in details, along with their photocatalytic performances as well as some other new applications.

Nonlinear and quantum optics with whispering gallery resonators

Abstract: Optical Whispering Gallery Modes (WGMs) derive their name from a famous acoustic phenomenon of guiding a wave by a curved boundary observed nearly a century ago. This phenomenon has a rather general nature, equally applicable to sound and all other waves. It enables resonators of unique properties attractive both in science and engineering. Very high quality factors of optical WGM resonators persisting in a wide wavelength range spanning from radio frequencies to ultraviolet light, their small mode volume, and tunable in- and out- coupling make them exceptionally efficient for nonlinear optical applications. Nonlinear optics facilitates interaction of photons with each other and with other physical systems, and is of prime importance in quantum optics. In this paper we review numerous applications of WGM resonators in nonlinear and quantum optics. We outline the current areas of interest, summarize progress, highlight difficulties, and discuss possible future development trends in these areas.

Lanthanide-Doped Upconversion Nanoparticles: Emerging Intelligent Light-Activated Drug Delivery Systems.

Abstract: The development of drug delivery systems (DDSs) using near infrared (NIR) light and upconversion nanoparticles (UCNPs) has generated intensive interest over the past five years. These NIR-initiated DDSs not only offer a high degree of spatial and temporal determination of therapeutic release but also provide precise control over the released dosage. Furthermore, these nanoplatforms confer several advantages over conventional light-based DDSs-NIR offers better tissue penetration depth and a reduced risk of cellular photo-damage caused by exposure to light at high-energy wavelengths (e.g., ultraviolet light, <400 nm). The development of DDSs that can be activated by low intensity NIR illumination is highly desirable to avoid exposing living tissues to excessive heat that can limit the in vivo application of these DDSs. This encompasses research in three directions: (i) enhancing the quantum yield of the UCNPs; (ii) incorporation of photo-responsive materials with red-shifted absorptions into the UCNPs; and (iii) tuning the UCNPs excitation wavelength. This review focuses on recent advances in the development of NIR-initiated DDS, with emphasis on the use of photo-responsive compounds and polymeric materials conjugated onto UCNPs. The challenges that limit UCNPs clinical applications, alongside with the aforementioned techniques that have emerged to overcome these limitations, are highlighted.

Analyzing Cell Death by Nuclear Staining with Hoechst 33342.

Abstract: The nuclei of healthy cells are generally spherical, and the DNA is evenly distributed. During apoptosis the DNA becomes condensed, but this process does not occur during necrosis. Nuclear condensation can therefore be used to distinguish apoptotic cells from healthy cells or necrotic cells. Dyes that bind to DNA, such as Hoechst 33342 or 4',6-diamidino-2-phenylindole (DAPI), can be used to observe nuclear condensation. These dyes fluoresce at 461 nm when excited by ultraviolet light and can therefore be visualized using conventional fluorescent microscopes equipped with light sources that emit light at ∼350 nm and filter sets that permit the transmission of light at ∼460 nm. This protocol describes staining and visualization of cells stained with Hoechst 33342, but it can be adapted for staining with DAPI or other dyes.

Mechanisms of DNA Repair by Photolyase and Excision Nuclease (Nobel Lecture).

Abstract: Ultraviolet light damages DNA by converting two adjacent thymines into a thymine dimer which is potentially mutagenic, carcinogenic, or lethal to the organism. This damage is repaired by photolyase and the nucleotide excision repair system in E. coli by nucleotide excision repair in humans. The work leading to these results is presented by Aziz Sancar in his Nobel Lecture.

Inactivation of Escherichia coli, Bacteriophage MS2, and Bacillus Spores under UV/H2O2 and UV/Peroxydisulfate Advanced Disinfection Conditions

Abstract: Ultraviolet light (UV) combined with peroxy chemicals, such as H2O2 and peroxydisulfate (PDS), have been considered potentially highly effective disinfection processes. This study investigated the inactivation of Escherichia coli, bacteriophage MS2, and Bacillus subtilis spores as surrogates for pathogens under UV/H2O2 and UV/PDS conditions, with the aim to provide further understanding of UV-based advanced disinfection processes (ADPs). Results showed that one additional log of inactivation of E. coli was achieved with 0.3 mM H2O2 or PDS at 5.2 × 10–5 Einstein·L–1 photo fluence (at 254 nm) compared with UV irradiation alone. Addition of H2O2 and PDS greatly enhanced the inactivation rate of MS2 by around 15 folds and 3 folds, respectively, whereas the inactivation of B. subtilis spores was slightly enhanced. Reactive species responsible for the inactivation were identified to be •OH, SO4·–, and CO3·– based on manipulation of solution conditions. The CT value of each reactive species was calculated with r...

New function of the Yb 3+ ion as an efficient emitter of persistent luminescence in the short-wave infrared

Abstract: The trivalent ytterbium (Yb3+) ion has been extensively used as an emitter in short-wave infrared (SWIR) lasers, a sensitizer to activate other lanthanide ions for up-conversion luminescence, and a spectral converter in Ln3+-Yb3+ doubly doped quantum cutting phosphors. Here we report a new function of the Yb3+ ion—as an efficient emitting center for SWIR persistent luminescence. We have developed the first real SWIR persistent phosphor, MgGeO3:Yb3+, which exhibits very-long persistent luminescence at around 1000 nm for longer than 100 h. The MgGeO3:Yb3+ phosphor is spectrally transparent to visible/near-infrared light (~400–900 nm) and is a promising ultraviolet-to-SWIR spectral convertor. The MgGeO3:Yb3+ phosphor also exhibits a photostimulated persistent luminescence capability, where the SWIR persistent emission in an ultraviolet-light pre-irradiated sample can be rejuvenated by low-energy light (white or red light) stimulation. The MgGeO3:Yb3+ phosphor is expected to have promising applications in biomedical imaging, night-vision surveillance and photovoltaics. A material that emits short-wave infrared light for more than 100 h after switching off the exciting light has been developed. Materials that emit light for an appreciable time after the exciting light source has been turned off—persistent phosphors—have been extensively studied in the visible region and have found commercial application as night-vision materials. But, until now, none had been found in the short-wave infrared region (900–1700 nm). Now, Zhengwei Pan at the University of Georgia in the USA and co-workers have found that MgGeO3 doped with trivalent ytterbium (Yb3+) ions luminesces at a wavelength of about 1000 nm for over 100 h after turning off the exciting ultraviolet light source. The researchers expect this phosphor to find application in biomedical imaging, night-vision devices and solar cells.

Nanocrystalline Ce-doped copper ferrite: synthesis, characterization, and its photocatalyst application

Abstract: In the current study and attempt is made to synthesized the cerium-doped copper ferrite nanoparticles (CuFe2−xCexO4) through an auto-combustion method with the aid of nitrate precursors such as copper(II), iron(III), and cerium(III (in an aqueous solution. Besides, the effect of different concentrations of various type of capping agents such as lactose and glucose on the morphology and particle size of final products was investigated. The structural, morphological, and optical properties of as-obtained products were characterized extensively by techniques such as FT-IR, XRD, EDX, SEM, TEM, and UV–vis. Furthermore, the magnetic property of as-prepared CuFe2−xCexO4 nanoparticles was also investigated with vibrating sample magnetometer at room temperature. Moreover, the as-prepared Ce-doped CuFe2O4 nanoparticles were used as efficient photocatalyst for the photocatalytic degradation of harmful organic dye, i.e. methyl orange under ultraviolet light.

A high-performance self-powered broadband photodetector based on a CH3NH3PbI3 perovskite/ZnO nanorod array heterostructure

Abstract: Here we report a self-powered photodetector based on a ZnO/CH3NH3PbI3 heterojunction and a MoO3 hole-transport layer. The organolead iodide perovskite photodetector is sensitive to broadband wavelengths from the ultraviolet light to the entire visible light region (250–800 nm), showing a high photo-responsivity of 24.3 A W−1 and a high detectivity value of 3.56 × 1014 cm Hz1/2 W−1 at 500 nm without external bias voltage. Meanwhile, we found that the photodetective performances are closely related to the thickness of the MoO3 layer, which acts as a hole-transport layer and an electron-blocking layer and can effectively decrease the recombination of holes and electrons. Additionally, the as-fabricated photodetector exhibits good stability and only 9.3% photoelectric response current decay after a 3-month illumination test. The high detectivity and responsivity of such a ZnO nanorod/perovskite heterojunction are clearly demonstrated and should be widely applicable to other photoelectric detection devices.

Assessing and Reducing the Toxicity of 3D-Printed Parts

Abstract: 3D printing is gaining popularity by providing a tool for fast, cost-effective, and highly customizable fabrication. However, little is known about the toxicity of 3D-printed objects. In this work, we assess the toxicity of printed parts from two main classes of commercial 3D printers, fused deposition modeling and stereolithography. We assessed the toxicity of these 3D-printed parts using zebrafish (Danio rerio), a widely used model organism in aquatic toxicology. Zebrafish embryos were exposed to 3D-printed parts and monitored for rates of survival, hatching, and developmental abnormalities. We found that parts from both types of printers were measurably toxic to zebrafish embryos, with STL-printed parts significantly more toxic than FDM-printed parts. We also developed a simple post-printing treatment (exposure to ultraviolet light) that largely mitigates the toxicity of the STL-printed parts. Our results call attention to the need for strategies for the safe disposal of 3D-printed parts and printer wa...

A light-stimulated synaptic transistor with synaptic plasticity and memory functions based on InGaZnOx–Al2O3 thin film structure

Abstract: In this work, a synaptic transistor based on the indium gallium zinc oxide (IGZO)–aluminum oxide (Al2O3) thin film structure, which uses ultraviolet (UV) light pulses as the pre-synaptic stimulus, has been demonstrated. The synaptic transistor exhibits the behavior of synaptic plasticity like the paired-pulse facilitation. In addition, it also shows the brain's memory behaviors including the transition from short-term memory to long-term memory and the Ebbinghaus forgetting curve. The synapse-like behavior and memory behaviors of the transistor are due to the trapping and detrapping processes of the holes, which are generated by the UV pulses, at the IGZO/Al2O3 interface and/or in the Al2O3 layer.

Effects of Ultraviolet Light and High‐Pressure Processing on Quality and Health‐Related Constituents of Fresh Juice Products

Abstract: Fresh juices are highly popular beverages in the global food market. They are perceived as wholesome, nutritious, all-day beverages. For a fast growing category of premium juice products such as cold-pressed juices, minimal-processing nonthermal techniques such as ultraviolet (UV) light and high-pressure processing (HPP) are expected to be used to extend shelf-life while retaining physicochemical, nutritional, and sensory characteristics with reduced microbial loads. Also, UV light and HPP are approved by regulatory agencies and recognized as one of the simplest and very environmentally friendly ways to destroy pathogenic organisms. One of the limitations to their more extensive commercial application lies in the lack of comparative effects on nutritional and quality-related compounds in juice products. This review provides a comparative analysis using 92 studies (UV light: 42, HPP: 50) mostly published between 2004 and 2015 to evaluate the effects of reported UV light and HPP processing conditions on the residual content or activity of bioactive compounds such as vitamins, polyphenols, antioxidants, and oxidative enzymes in 45 different fresh fruit and vegetable juices (low-acid, acid, and high-acid categories). Also, the effects of UV light and HPP on color and sensory characteristics of juices are summarized and discussed.

Effect of TiO2 nanoparticles on the physico-mechanical and ultraviolet light barrier properties of fish gelatin/agar bilayer film

Abstract: Bilayer gelatin/agar films containing different concentrations of TiO2 (0.5, 1, and 2 g/100 g) were prepared by incorporation of anatase titanium dioxide nanoparticles in the fish gelatin layer of the bilayers. Gelatin/agar bilayer film was produced from the monolayers using the casting method in two steps and their microstructural, physical, mechanical and optical characteristics were studied. Results showed that the addition of TiO2 decreased water vapor permeability of the bilayers more than 30%, upon increasing TiO2 content to 2 (g/100 g). However, swelling ratio and moisture content increased with the increase in the nano-TiO2 content, probably due to the hydrophilic nature of the TiO2 nanoparticles. The tensile strength of the bilayer films increased from 10.80 to 13.91 MPa upon increasing nano-TiO2 content from 0 to 0.5 (g/100 g); however, tensile strength decreased with further increase of the nanoparticle concentration. In addition, the metallic nature of nano-TiO2 considerably improved the barrier properties of the bilayer films against UV light at low concentration, while it increased their opacity. This property might help in the preservation of light-sensitive foods, but more studies on real food systems are required.

Dopamine Modified Organic–Inorganic Hybrid Coating for Antimicrobial and Osteogenesis

Abstract: A hybrid coating composed of hydroxyapatite (HA), Ag nanoparticles (NPs), and chitosan (CS) was successfully prepared on a Ti substrate by a layer-by-layer assembly process. A polydopamine-assisted (PDA-assisted) coating showed a good bond with HA. Ag NPs were uniformly distributed into the hybrid coating through a solution method and ultraviolet light reduction. A CS nanofilm was deposited via spin-coating to control the release of Ag+ from the hybrid coating. The results disclosed that the 3-layer CS coating could efficiently control the release of Ag+ from the hybrid coating via the Fickian diffusion mechanism and that the PDA/HA/Ag/CS-1 coating exhibited antibacterial ratios of 63.0% and 51.8% against E. coli and S. aureus, respectively. Furthermore, the normal structure of E. coli was obviously destroyed by two types of Ag doped coatings. The cell viability assay showed that CS effectively reduced the cytotoxicity of the hybrid coating after a 7 day incubation. The hybrid coating presented high ALP a...

Photo-degradation of methylene blue: photocatalyst and magnetic investigation of Fe2O3–TiO2 nanoparticles and nanocomposites

Abstract: In this work at the first step Fe2O3 nanoparticles were synthesized via a fast microwave method. Then Fe2O3–TiO2 nanocomposites were synthesized by a sonochemical-assisted method. The prepared products were characterized by X-ray diffraction pattern, scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. Alternating gradient force magnetometer illustrated super-paramagnetic property of Fe2O3 nanoparticles. The photocatalytic behaviour of Fe2O3–TiO2 nanocomposites was investigated using the degradation of methylene blue under ultraviolet light irradiation. The outcomes confirm that nanocomposites have applicable magnetic and photocatalytic performance. Fe2O3–TiO2 nanostructures were added to cellulose acetate and because of presence of nano-additives properties of polymeric matrix like flame retardancy were increased.

Simultaneous Enhancements of UV-Shielding Properties and Photostability of Poly(vinyl alcohol) via Incorporation of Sepia Eumelanin

Abstract: Sepia eumelanin (SE), a biomacromolecule, was developed to prepare the excellent UV-shielding polymer material with better photostability. UV–vis transmittance spectra showed that poly(vinyl alcohol) PVA/SE film blocked most ultraviolet light below 300 nm even with a low concentration of SE (0.5 wt %), which still kept its high transparency in the visible spectrum. Rhodamine B photodegradation measurement further confirmed the excellent UV-shielding properties of PVA/SE film. FTIR indicated that the carbonyl absorption bands resulting from phtodegradation for PVA/SE film did not change after UV exposure for 2700 h. The tensile properties of neat PVA were deceased intensely after UV irradiation; however, those of PVA/SE film were reduced a little. Moreover, AFM indicated that the surface roughness of PVA/SE film was much lower than that of a neat PVA one. It could be concluded that SE reduced the PVA degradation rate dramatically, revealing enhanced photostability of PVA/SE film. The mechanism for outstand...

Optically responsive supramolecular polymer glasses

Abstract: The reversible and dynamic nature of non-covalent interactions between the constituting building blocks renders many supramolecular polymers stimuli-responsive. This was previously exploited to create thermally and optically healable polymers, but it proved challenging to achieve high stiffness and good healability. Here we present a glass-forming supramolecular material that is based on a trifunctional low-molecular-weight monomer ((UPyU)3TMP). Carrying three ureido-4-pyrimidinone (UPy) groups, (UPyU)3TMP forms a dynamic supramolecular polymer network, whose properties are governed by its cross-linked architecture and the large content of the binding motif. This design promotes the formation of a disordered glass, which, in spite of the low molecular weight of the building block, displays typical polymeric behaviour. The material exhibits a high stiffness and offers excellent coating and adhesive properties. On account of reversible dissociation and the formation of a low-viscosity liquid upon irradiation with ultraviolet light, rapid optical healing as well as (de)bonding on demand is possible.