Ultraviolet Radiation Energy Research Articles

Impact of ultraviolet radiation energy curing UV primer on adhesion of bamboo lumber surfaces and colorimetry of UV inkjet coatings

ABSTRACT The application of UV digital inkjet printing technology in the home furnishing industry has greatly enriched the diversity of decorative panels. Controlling the UV radiation energy curing UV primers process has a significant impact on the performance of UV printing coatings on bamboo surfaces. The results showed that the UV radiation energy is in the range of 60∼300 mJ cm−2, the adhesion of the UV primer on the surface of bamboo is the best when it is controlled at 180 mJ cm−2, which reaches the standard of 0 level; when the radiation energy reaches 240 mJ cm−2, the content of oxygen-containing functional groups on the surface of the primer is higher, the surface wettability is the best, and the roughness is also relatively high. When the radiation energy reaches 360 mJ cm−2, radiation energy that is too high would reduce the adhesion performance of the UV primer on the surface of bamboo lumber. In addition, the gloss difference of the UV ink coatings between adjacent parameter samples is small, while the color difference is more obvious. The energy of UV radiation should be controlled in the range of 180∼240 mJ cm−2 in the actual production application.

Exposed Body Surface Area-A Determinate for UV Radiant Energy in Human UV Exposure Studies.

Solar ultraviolet (UV) exposure of people and related health risk is mainly examined by estimating the received UV radiant exposure. However, for several effects such as DNA damage, vitamin D photosynthesis or the probability of developing skin cancer, UV radiant energy is important and with that the size of exposed skin area. There is also a complex interaction between body shape and behavior like sun exposure habits, so that careful analysis is necessary when estimating health effects from UV exposure. In this paper, knowledge on body shape and methods of calculating the total body surface area (BSA) are summarized. BSA depends mainly on the height and weight of a person as well as on gender, ethnicity and body shape. BSA and body shape differ significantly between different populations and both change during life. This paper proposes formulas for BSA that consider height, weight, gender, ethnicity and body shape. As the exposed BSA depends on clothing, finally an approach is presented which aims to calculate the size of body parts released by real garments. In summary, this paper will enable future researchers to quantify the exposed BSA by best matching their study population and consequently investigate risks caused by solar UV exposure.

Nitrogen-plasma doped ZnO-graphene oxide compounds production and their photocatalytic performance

• Nitrogen doping of ZnO improved their photocatalytic performance. • N -ZnO/GO reached high degradation rates in short times. • N -doping was efficiently carried out using a nitrogen plasma facility. • GO in N -ZnO/GO acts as electron transporter preventing recombination. The present work is aimed at developing ZnO compounds, doping them using a novel nitrogen plasma methodology, and supporting them on graphene oxide sheets, to efficiently carry out, the photodegradation of lignin. The synthesis of ZnO was carried out using a hydrothermal methodology using microwave heating. To provide explanation and support to this photocatalytic behavior, a complete set of characterization techniques was involved including UV–vis, Raman, and X-ray photoelectron (XPS) spectroscopies. Morphological and structural characterization was performed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The degradation tests were carried out under visible and ultraviolet radiation energy, reaching about 90% of lignin degradation in both cases. Our results demonstrate that nitrogen doping of ZnO, produced through a nitrogen plasma, favorably affects their photocatalytic performance.

Lactic acid photochemistry following excitation of S0 to S1 at 220 to 250 nm

AbstractLactic acid, a small α‐hydroxy acid, is a multifunctional molecule that is prevalent on modern Earth and found in abiotic environments. Recently, there has been interest in the photochemistry of carboxylic acids in general. Specifically, the photochemistry of lactic acid, due to its prevalence and functionality, has garnered attention by the biomass valorization and abiotic chemistry communities. However, aqueous lactic acid photochemistry studies are limited, and gas‐phase lactic acid photolysis had not been performed. This work combines theory and experiments to explore the gas‐phase and aqueous phase photochemistry of lactic acid following excitation of S0 to S1 at 220–250 nm. We find that lactic acid primarily photodecomposes via decarboxylation in both phases. In the gas phase, secondary chemistry leads to mainly CO2 and CO, while in the aqueous phase, subsequent radical chemistry leads to a variety of products with one to four carbons. Isotopic substitutions, including the use of 13C tagged lactic acid and using D2O as a solvent, are used to infer mechanistic pathways for the major photolysis products. Computation shows that individual conformers may contribute to the overall photochemistry to a different degree than their relative abundance would suggest. The identified products and proposed mechanisms shown here serve to illustrate the photochemistry of lactic acid in the presence of high‐energy ultraviolet radiation. This knowledge may aid process and catalyst design for biomass valorization/organic synthesis and may provide insight into abiotic chemistry in environments exposed to high energy ultraviolet radiation.

Real-time Ultraviolet Radiation Sensor Based on Modified Cladding Optical Fibers Technology

In this work, the performance of single-mode optical fibers (SMFs) for ultraviolet (UV) radiation monitoring and dosimetry applications is presented. In particular, this work will focus on the Radiation-Induced Absorption (RIA) phenomena in the Near-Infrared domain (NIR). Such phenomena play a very important role in the sensing mechanism for SMF. Single mode fibers with a diameter of 50 µm were used for this purpose. These fibers were dipped into germanium (Ge) solution with different concentrations (1, 3, and 5 wt%) to produce the sensing part of the sensor. For all optical fiber sensors under investigation, the results indicated the dependence of the RIA on the applied UV radiation energy. Also, a redshift in peak wavelength was obtained. The influence of Ge concentration on sensing efficiency was studied and the best results were obtained with 3 wt% concentration as compared to 1 wt % and 5 wt % concentrations. The presented sensor shows good sensitivity to UV radiation which makes it possible to be applied in medical applications.

A Novel Technique for Full-Field Deformation and Temperature Measurement by Ultraviolet Imaging: Experimental Design and Preliminary Results

Synchronous measurement of full-field temperature and deformation at high temperature especially more than 1273 K is of much significance especially for part applications of turbine structures and materials. Non-contact optical methods attract more and more attention, however, current methods all face different challenges, such as strong light reflection on the surface of the specimen, disturbing radiation from environment, complex equipment setup, limited measured temperature not higher than 900 ℃ and so on. In this work, we develop an innovative technique to overcome some current problems. The measurement system employing an ultraviolet (UV) imaging system is composed of a scientific complementary metal oxide semiconductor (sCMOS) camera, a lens and a UV bandpass filter. The UV bandpass filter was used for thermal radiation elimination to acquire high quality images at elevated temperatures for deformation field calculation suitable for digital image correlation (DIC) method. The UV sensitive sCMOS camera without using active illumination was employed to collect enough UV radiation energy and eliminate the interference of the external ambient light, which is applicable for high accuracy temperature field measurement. Our system can realize the synchronous capture of image and temperature acquisition with passive UV imaging system at temperature not lower than 1473K. The feasibility of the method was verified through heating molybdenum (Mo) and Ni-based superalloy IC21 materials. The temperature fields of Mo measured by the established imaging system up to 1835 K with error less than 0.25% showed the effectiveness for temperature measurement. The estimated deformation and temperature field of Ni-based superalloy IC21 up to 1473 K with measured temperature error less than 0.5% demonstrated well the great potential of the UV imaging system in simultaneous measurement of temperature and deformation fields at elevated temperatures.

Sol–gel synthesized ZnO/Mn–TiO2 core–shell nanocomposite and its elevated activity for methyl orange degradation

Photocatalysis is a new advanced oxidation process based on the irradiation of semiconductors such as TiO2 and ZnO for photodegradation of contaminants. In this process, the semiconductor absorbs the photon energy of ultraviolet radiation, generating highly reactive species for the degradation of organic compounds. It has been reported that doping of transition metals (e.g., Cu, Ni, Co, and Mn) into the structure of oxide semiconductors can reduce the band gap and expand their adsorption properties to the visible solar spectrum. Accordingly, a new hybrid photocatalyst of Mn-doped TiO2 / ZnO with an Mn content of 1 to 5 wt. % was synthesized via the sol–gel process followed by thermal calcinations in air at 500°C. The prepared photocatalyst powder was characterized in terms of crystalline structure, thermal property, surface morphology, and band gap energy level. Its photocatalytic performance was then assessed based on photodegradation of methylene orange under visible light irradiation. Compared with the pure TiO2 / ZnO, the lattice of Mn-doped TiO2 / ZnO was found to be more thermally stable, and thus phase transformation of anatase to rutile was postponed to a higher calcination temperature. The photocatalysis evaluation showed an increased activity of Mn–ZnO / TiO2 compared with pure TiO2 and TiO2 / ZnO under visible light irradiation. Accordingly, the highest degradation of 98% was obtained by the Mn–ZnO / TiO2 with 3 wt. % Mn.

Ultraviolet Radiant Energy-Dependent Functionalization Regulates Cellular Behavior on Titanium Dioxide Nanodots.

Titanium dioxide (TiO2) photofunctionalization has been demonstrated as an effective surface modification method for the osseointegration of implants. However, the insufficient understanding of the mechanism underlying photofunctionalization limits its clinical applications. Here, we report an ultraviolet (UV) radiant energy-dependent functionalization on TiO2 nanodots (TN) surfaces. We found the cell adhesion, proliferation, and osteogenic differentiation gradually increased with the accumulation of UV radiant energy (URE). The optimal functionalizing treatment energy was found to be 2000 mJ/cm2, which could regulate cell-specific behaviors on TN surfaces. The enhanced cell behaviors were regulated by the adsorption and functional site exposure of the extracellular matrix (ECM) proteins, which were the result of the surface physicochemical changes induced by the URE. The correlation between the URE and the reconstruction of surface hydroxyl groups was considered as an alternative mechanism of this energy-dependent functionalization. We also demonstrated the synergistic effects of FAK-RHOA and ERK1/2 signaling pathways on mediating the URE-dependent cell behaviors. Overall, this study provides a novel insight into the mechanisms of photofunctionalization, guiding the design of implants and the clinical practice of photofunctionalization.

Single-frequency laser pumped optical parametric oscillator at 226 nm

We demonstrate a narrow linewidth optical parametric oscillator (OPO), with a 452 nm signal radiation output, pumped by a 355 nm single frequency Nd:YAG laser. The pump laser can operate with a precisely controllable laser pulse firing time and so can the OPO output. The OPO is composed of two beta barium borate crystals and arranged in a linear cavity configuration. The cavity is not actively stabilized. The maximum output pulse energy achieved for the 452 nm signal is 11 mJ with a 45 mJ pump energy. The spectrum and spatial shape are measured to be in accordance with the pulse characteristics of a narrow linewidth laser. It is shown that the signal pulse is extremely dependent on the pump pulse. Then the signal pulse is frequency doubled to generate about 1.5 mJ in energy of ultraviolet radiation at 226 nm.

Ultraviolet antireflectance and high energy facets induced superhydrophilicity in SnO2 nano-arrayed thin films

Ultraviolet (UV) radiation carries higher energy than visible light which causes potential damages to eye, immune system and skin. Even though antireflective glasses available in market are effective against visible light, they reflect high levels of UV radiation. Hence development of coatings which neither transmit nor reflect high energy UV radiation is highly desirable. Herein, we demonstrate the direct growth of SnO2 nanostructured arrays with broadband antireflectance using a simple spray pyrolysis method. An investigation on nanostructure evolution has been carried out which revealed that the growth mechanism has a strong dependence on deposition temperature, time and solvent used. SnO2 nanostructured arrays exhibited broadband antireflectance with less than 0.5% reflectance and near zero transmittance in high energy UVB (280–315 nm) wavelength region due to the graded refractive index and scattering provided by nanoarrays. The prepared samples are superhydrophilic in nature due to the presence of high energy facets which account for their observed anticondensation properties. These multifunctional SnO2 nanostructured arrays may have potential applications in sunglasses, safety glasses, windows, optical materials and solar panels owing to their antireflective, antifogging and self-cleaning properties.

Enhanced lipid content in Chlorella sp. FC2 IITG via high energy irradiation mutagenesis

High energy ultra-violet radiation was used to induce mutations in the wild type strain Chlorella sp. FC2 IITG and the mutants obtained were screened for enhanced lipid content targeted towards biodiesel production. Screening of mutants under nitrogen starved photoautotrophic condition showed five mutant strains with higher lipid content as compared to the wild type strain. Maximum neutral lipid content of 22.26% (w/w, DCW) was found for FC2-25UV mutant strain, which was 48.4% higher than that of wild type culture. Further characterization under photoautotrophic two stage high cell density cultivation of lipid rich FC2-25UV resulted in total lipid content of 68% (w/w, DCW), which was 21.43% higher than the wild type strain with a marginal improvement of 11% in the total lipid productivity. Comparison of enzyme activity assays under nitrogen starved conditions in both the strains revealed an 18.2% and 31.25% increase in acetyl CoA carboxylase and di-acyl-glycerol transferase activity of mutant. The FAME composition analysis showed 41.5% and 24% increase in the fractions of C18:2 and C18:1 in the mutant strain when compared to the wild type strain with no significant difference in the other FAME fractions. Thus, the mutant strain could be a potential candidate for biodiesel production.

Evaluation of the Resistance of a Polypropylene Geotextile Against Ultraviolet Radiation.

The exposure to solar radiation (mainly due to the action of ultraviolet radiation) is one of the main causes for the premature failure of many polymeric materials, including the geotextiles. In this work, a nonwoven polypropylene geotextile (stabilized with a known amount of a hindered amine light stabilizer) was exposed to ultraviolet-aging tests, both in the laboratory (accelerated conditions) and outdoors (natural conditions). The damage occurred in the geotextile (caused by the ultraviolet-aging tests) was evaluated quantitatively (by monitoring changes in its mass per unit area, thickness, and tensile properties) and qualitatively (by scanning electron microscopy). The results, among other findings, showed that: (1) the ultraviolet-aging tests (both in the laboratory and outdoors) induced relevant damage in the polypropylene fibers of the geotextile (transverse cracks), leading to the deterioration of its tensile behavior, (2) the amount of degradation increased with the increase of the ultraviolet radiant energy, (3) the laboratory tests caused a faster deterioration of the polypropylene fibers than the outdoor tests, and (4) the degradation found by scanning electron microscopy in the polypropylene fibers correlated well with the deterioration occurred in the tensile behavior of the geotextile.

Light Conversion and Scattering in UV Protective Textiles

Abstract The primary cause of skin cancer is believed to be a long exposure to solar ultraviolet radiation (UV-R) crossed with the amount of skin pigmentation in the population. It is believed that in childhood and adolescence 80% of UV-R gets absorbed, whilst in the remaining 20% gets absorbed later in the lifetime. This suggests that proper and early photoprotection may reduce the risk of subsequent occurrence of skin cancer. Textile and clothing are the most suitable interface between environment and human body. It can show UV protection, but in most cases it does not provide full sun screening properties. UV protection ability highly depends on large number of factors such as type of fibre, fabric surface and construction, type and concentration of dyestuff, fluorescent whitening agent (FWA), UV-B protective agents, as well as nanoparticles, if applied. Based on electronically excited state by energy of UV-R (usually 340-370 nm), the molecules of FWAs show the phenomenon of fluorescence giving to white textiles high whiteness of outstanding brightness by reemitting the energy at the blue region (typically 420-470 nm) of the spectrum. By absorbing UV-A radiation, optical brightened fabrics transform this radiation into blue fluorescence, which leads to better UV protection. Natural zeolites are rock-forming, microporous silicate minerals. Applied as nanoparticles to textile surface, it scatters the UV-R resulting in lower UV-A and UV-B transmission. If applied with other UV absorbing agents, e.g. FWAs, synergistic effect occurs. Silicones are inert, synthetic compounds with a variety of forms and uses. It provides a unique soft touch, is very resistant to washing and improves the property of fabric to protect against UV radiation. Therefore, the UV protective properties of cotton fabric achieved by light conversion and scattering was researched in this paper. For that purpose, the stilbene-derived FWAs were applied on cotton fabric in wide concentration range without/with the addition of natural zeolite or silicone- polydimethylsiloxane. UV protection was determined in vitro through ultraviolet protection factor. Additionally, the influence to fabric whiteness and hand was researched

Laser ultraviolet fragmentation of homogeneous (CF3I) n clusters in a molecular beam and (CF3I) n clusters inside of large (Xe) m clusters or on their surface

The fragmentation of homogeneous (CF3I)n clusters (where n ≤ 45 is the average number of molecules in a cluster) in a molecular beam, as well as (CF3I)n clusters inside of large (Xe)m clusters (where m ≥ 100 is the average number of atoms in a cluster) or on their surface, by laser ultraviolet radiation has been studied. It has been found that the indicated three types of (CF3I)n clusters have different stabilities with respect to fragmentation and strongly different dependences of the fragmentation probability on the energy of ultraviolet radiation. Fragmentation at low energies and the weakest energy dependence of the probability of fragmentation are observed for homogeneous clusters, a stronger dependence is characteristic of (CF3I)n clusters localized inside (Xe)m clusters, and the strongest dependence is observed for (CF3I)n clusters on the surface of (Xe)m clusters. Possible reasons for such a character of the observed dependences have been discussed.

Photo-Oxidation of PVC-Coated Membrane Material

To study photo-oxidation behavior of PVC-coated membrane material under different UV radiation intensities, three intensities of Ultraviolet (UV) irradiation were carried out. The yellowness indexes under different weathering conditions were measured, as well as UV-Vis spectrometry. Result shows that the photo-oxidation mechanism doesn’t change under different UV intensities, but the photo-oxidation reaction rates are not equal when the cumulative UV radiation energy is same. A conclusion is obtained that photo-oxidation reaction rate under different intensities is out of proportion to UV intensity. And according to Schwarzschild’s law, an equation form is established to predict material’s life.

Analytical methods in photoelectrochemical treatment of phenol

The aim of the study was to propose a treatment of simulated wastewater containing phenol by photocatalytic and photolytic processes and analyze the toxicity of these phenolic solutions. Two treatment systems were performed with UV radiation, solid electrodes and electric potential. In the first system (S1) phenol concentration was determined by UV direct spectrophotometry (269 nm) and in the second (S2) by direct photometric method (4-aminoantipyrine). Toxicological tests were carried out using two microorganisms: Escherichia coli and Saccharomyces cerevisiae. S1 results showed that erroneous conclusions can be drawn by absorbance values increase at phenol peak. Nevertheless, direct photometric method was able to identify phenol reduction in S2 and the proposed treatments degraded phenol in solution. Also, in treatment using high energy ultraviolet radiation (UVC), the phenol degradation was mainly due to the photolytic process

Photooxidative degradation of carboxylated poly(vinyl chloride)

Thin films of poly(vinyl chloride), PVC, and carboxylated poly(vinyl chloride), C-PVC, containing 1.8% of carboxyl groups were exposed to high energy ultraviolet radiation (λ = 254 nm) in laboratory conditions. The photochemical reactions in irradiated samples were studied by FTIR and UV–Vis spectroscopy, gel permeation chromatography and gravimetric estimation of insoluble gel. It was found that photodegradation and photocrosslinking in C-PVC is accelerated, whereas photodehydrochlorination is retarded comparing to these processes in PVC. Photooxidation investigated on the base of reaction leading to formation of hydroxyl groups is also more efficient in modified PVC. However, the total amount of carbonyl groups is much lower in UV-irradiated C-PVC than that in PVC. It indicates that competitive reactions (destruction of carboxyl groups and formation of new carbonyls) occur simultaneously in C-PVC chains. The influence of carbonyl groups on photochemical processes can be explained by an efficient Norrish I and II reactions as well as by energy transfer from absorbing species to weak chemical bonds.

Cutaneous sensory nerves: mediators of phototherapeutic effects?

Exposures to ultraviolet radiation (UVR) during accidental or voluntary sun exposure or treatment with phototherapy or photochemotherapy have a significant impact on the skin. Many skin diseases such as psoriasis, atopic dermatitis, or cutaneous T-cell lymphoma significantly improve by photo(chemo)therapy, though the mechanisms behind the therapeutic effects of photo(chemo)therapy are still far from understood. Various pathways and means through which the energy of UVR from natural or artificial sources is ultimately transformed into biologic effects within the skin have been suggested and cutaneous sensory nerves, neuropeptides, neurotrophins, and certain nerve-related receptors have been among them. In fact a three-dimensional network of sensory nerve fibers derived from dorsal root ganglia intersperses all layers of the skin including the epidermis. In this forefront of defense against environmental impacts (including UVR) on the skin, sensory nerve fibers become targets by itself and closely contact resident and infiltrating cutaneous cells. Thus, terminals of cutaneous sensory nerve fibers, and neuropeptides within these fibers, are in a central position to participate in mediating therapeutic effects of photo(chemo)therapy.

Electrical behavior and vacuum ultraviolet radiation efficiency of monofilamentary xenon dielectric barrier discharges

In this paper we report the experimental investigation of a pure xenon monofilamentary dielectric barrier discharge (DBD), using a high voltage power supply. Stable microdischarges were achieved and studied in the pressure range of 100–400Torr, at frequencies between 10 and 40kHz. Successive 3ns exposure time snapshots of the discharge clearly show how it built up. Its diameter was about 0.26mm. The discharge voltage and current were determined from the measurement of the supply voltage and current. Compared to those in argon, the current pulses were shorter (less than 30ns, above 200Torr) and had much higher peak values. Ignition voltages were also higher in the heavier gas. Electrical energy and vacuum ultraviolet radiation energy of the second continuum of xenon were both independent of frequency. They both varied almost linearly with pressure. The measured DBD vuv efficiency of a single xenon microdischarge reported here was between 55% and 60%, and the maximum value was reached for 200Torr. These values were twice those reported for multifilamentary discharges working with a sinusoidal supply. They were similar to those obtained for multifilamentary dielectric barrier discharges excited with short voltage pulses.

Chromatic behavior of inorganic pigments in restoration mortars (nonhydraulic lime, hydraulic lime, gypsum, and portland cement). A comparative study

AbstractSpectral diffuse reflectance was used to make a comparative study of the chromatic behavior (stability, coloring power and effects of time, thermal gradients, and high energy ultraviolet radiation) of the inorganic pigments ultramarine blue, green earth, molybdenum orange, zinc yellow, chrome yellow, chrome green, ochre, and natural sienna when mixed with the binders: nonhydraulic lime, hydraulic lime, Portland cement, and gypsum. The results show acute interference of the limes and the Portland cement, and, to a lesser extent, of the gypsum on the initial colors of ultramarine blue, molybdenum orange, and chrome yellow. The other pigments studied showed good stability in the four binders. Time, thermal gradients, and high energy ultraviolet radiation caused no appreciable color changes, except in the case of chrome yellow, which presented slight changes over time. © 2006 Wiley Periodicals, Inc. Col Res Appl, 32, 65–70, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20289