Duration Of Ultraviolet Irradiation Research Articles

Raman enhancement properties of TiO2/Ag carbon fiber cloth using the ultraviolet-induced method: high sensitivity, flexible and reusable

We report a low-cost fabrication strategy to prepare a large-area carbon fiber cloth (CFC) coated by Ag nanoparticles (AgNPs) as a flexible surface-enhanced Raman scattering substrate. AgNPs were deposited on a hydrophilized CFC by ultraviolet (UV) irradiation of AgNO3 solution, named UV-AgNPs@CFC. The UV irradiation duration and AgNO3 solution concentration can affect the AgNPs structure. SERS property is investigated using rhodamine 6 G (R6G) and crystal violet (CV) as standard analytes and the detection concentration level is down to 10−10 mol/L. The analytical enhancement factor can reach 1.22 × 109. Also, the substrate has remarkable stability and uniformity; the relative standard deviation (RSD) of the characteristic peak calculated at 611cm−1 is 14.4%. Additionally, the UV-AgNPs@CFC substrate can detect two different molecules simultaneously. Our flexible SERS substrate enables efficient molecular extraction and Raman measurements on the curved surface of apples. The detection concentration level for CV is down to 10−5 mol/L. Moreover, the electric field distribution of the hybrid structure is simulated by the finite difference time domain and COMSOL Multiphysics software, and the maximal electric field intensity is 25.7 V/m. Meanwhile, we deposited AgNPs on the TiO2 nanorods-modified CFC (TiO2-CFC) by UV irradiation. A reusable self-cleaning UV-AgNPs@TiO2-CFC substrate was fabricated.

Optimization of ultraviolet irradiation of Clarias gariepinus (Burchell, 1822) eggs for androgen production.

The optimum distance and duration of ultraviolet (UV) irradiation for the complete inactivation of African catfish Clarias gariepinus egg nucleus was investigated in this study. The UV light was suspended above the unfertilized eggs at four distances (5, 10, 20 and 30 cm) and for five durations (1, 2, 3, 4 and 5 min). Then, the irradiated eggs were activated with sperm from diploid C. gariepinus and cold shocked at 5°C for 5 min just moments before cell cleavage. Ploidy analysis was performed using karyotype chromosome counting. The results obtained suggested that the further the distance, the better the hatchability rate, however prolonged duration seemed to significantly reduced hatchability. All treatments with surviving progenies at the end of the study showed evidence of successfully diploid gynogen (2n = 56) induction at different percentages. However, the optimal protocol that gave a moderately high hatchability/survival rate and completely induced gynogens was exposure of the eggs to UV irradiation at 20 cm for 1 min. It was concluded that the distance and duration of UV irradiation affects gynogenetic induction in African catfish C. gariepinus.

Degradation rate of DNA scaffolds and bone regeneration

Scaffolds implanted into bone defect sites must achieve optimal biodegradation rates while appropriately filling the void as new bone formation progresses. We recently developed a unique biomaterial consisting of salmon deoxyribose nucleic acid (DNA) and protamine, which can be used as an osteoconductive scaffold for tissue engineering. The aim of the present study was to elucidate how the degradation rate of the scaffold affects bone regeneration. We examined the relationships between the degradation rate of salmon DNA scaffolds and new bone formation using a rat skin flank subcutaneous model and rat calvarial defect model. The degradation rates of the scaffolds were proportional to the durations of pretreatment with ultraviolet (UV) light irradiation. The biodegradation rates of the scaffolds were also dependent on the duration of UV irradiation, as tested a subcutaneous tissue implantation. Scaffolds irradiated with UV light for 0.5 h maintained gradual biodegradation of phosphate compared with scaffolds irradiated for 0 or 3 h. In the calvarial defect model, we found that new bone formation was higher in rats treated with scaffolds irradiated with UV light for 0.5 h compared with those irradiated with UV light for 0 or 3.0 h. The present results suggest that bioengineering of scaffolds for biodegradation is important to regenerate bone. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 122-128, 2019.

MRNA Interactome Capture from Plant Protoplasts.

RNA-binding proteins (RBPs) determine the fates of RNAs. They participate in all RNA biogenesis pathways and especially contribute to post-transcriptional gene regulation (PTGR) of messenger RNAs (mRNAs). In the past few years, a number of mRNA-bound proteomes from yeast and mammalian cell lines have been successfully isolated through the use of a novel method called "mRNA interactome capture," which allows for the identification of mRNA-binding proteins (mRBPs) directly from a physiological environment. The method is composed of in vivo ultraviolet (UV) crosslinking, pull-down and purification of messenger ribonucleoprotein complexes (mRNPs) by oligo(dT) beads, and the subsequent identification of the crosslinked proteins by mass spectrometry (MS). Very recently, by applying the same method, several plant mRNA-bound proteomes have been reported simultaneously from different Arabidopsis tissue sources: etiolated seedlings, leaf tissue, leaf mesophyll protoplasts, and cultured root cells. Here, we present the optimized mRNA interactome capture method for Arabidopsis thaliana leaf mesophyll protoplasts, a cell type that serves as a versatile tool for experiments that include various cellular assays. The conditions for optimal protein yield include the amount of starting tissue and the duration of UV irradiation. In the mRNA-bound proteome obtained from a medium-scale experiment (107 cells), RBPs noted to have RNA-binding capacity were found to be overrepresented, and many novel RBPs were identified. The experiment can be scaled up (109 cells), and the optimized method can be applied to other plant cell types and species to broadly isolate, catalog, and compare mRNA-bound proteomes in plants.

Effects of Carbon Black and Titanium Dioxide on Ultraviolet Weathering of Wood Flour-HDPE/Lumber Composites Using Multi-phase Co-extrusion Technology

A new type of wood-plastic/lumber composite (WPLC) was fabricated with laminated veneer lumber as a core, and the traditional wood-plastic composite (WPC) as a shell layer using multi-phase co-extrusion technology. This WPLC was used to manufacture a window frame, and the effects of inorganic pigments (carbon black (CB), titanium dioxide (TiO2), and their mixtures) on the decorative effect and ultraviolet (UV) weathering performance of the shell layer of the window frame were investigated. Weathering variables included UV irradiation duration and water spraying cycles for up to 6000 h. The surface color was analyzed by spectrophotometry during weathering. In addition, a scanning electron microscopy analysis and Fourier transform infrared spectroscopy analyzed the weathering properties of the WPLC shell layer. The results showed that (1) different decorative effects (white, grey, and black color) of the window frames were achieved by incorporating CB, TiO2, and their mixture; (2) the composites incorporated with CB and/or TiO2 exhibited less discoloration and fewer surface cracks; (3) the composites with CB and TiO2 showed a better photo-stability than those with a UV stabilizer (UV326). The overall color change (△E) of the composites incorporated with UV326, TiO2, and CB was 20.0, 11.7, and 10.8, respectively, after 3000 h of weathering; and (4) a combination of CB and TiO2 showed a synergistic effect on alleviating the photo-oxidation process of the WPC shell layers, which confirmed its UV-shielding effect.

Sulfur-Free Prevulcanization of Natural Rubber Latex by Ultraviolet Irradiation

The possibility of prevulcanizing natural rubber latex via ultraviolet (UV) irradiation was investigated using 2-hydroxy-2-methyl-1-phenylpropanone as the photoinitiator and 1,9-bis(acryloyloxy)nonane as the coagent. Effects of the following process variables were assessed on the tensile strength and the cross-link density of thin films prepared from the prevulcanized natural rubber (PVNR) latex: the duration of UV irradiation, the distance between the light source and the latex being irradiated, the mixing time of the latex with the coagent and the phtoinitiator, the depth of the latex pool, and the mass ratio of the photoinitiator to the coagent used. The PVNR films produced under optimal conditions had nearly 4-fold the tensile strength of the film produced without UV irradiation. Fourier transform infrared spectroscopy and 13C nuclear magnetic resonance spectroscopy were used to assess the UV reactions, and a mechanism was proposed for UV-induced prevulcanization with the above identified photoinitiat...

Ultraviolet exposure of Gafchromic XR-RV3 and XR-SP2 films.

Gafchromic film has been used for X‐ray dose measurement in diagnostic examinations. Their use has been initiated for three‐dimensional X‐ray dose measurement by using the high‐resolution characteristics of Gafchromic films in computed tomography. However, it is necessary to solve the problem of nonuniform thickness in the active layers of Gafchromic films. A double exposure technique using X‐rays is performed in therapeutic radiology; it is difficult to use in a diagnostic examination because of the heel effect. Therefore, it is suggested that ultraviolet (UV) rays be substituted for X‐rays. However, the appropriate UV wavelength is unknown. In this study, we aimed to determine which UV wavelengths are effective to expose Gafchromic XR‐RV3 and XR‐SP2. UV lamps with peak wavelengths of 245 nm, 310 nm, and 365 nm were used. The three UV wavelengths were used to irradiate Gafchromic XR‐RV3 and XR‐SP2 films for 60 min, and irradiation was repeated every 60 min for 600 min thereafter. Films were scanned after each irradiation period on a flatbed scanner. The images were split into their red‐green‐blue components, and red images were stored using ImageJ version 1.44o image analysis software. Regions of interest (ROI), 0.5 inches in diameter, were placed at the centers of the subtracted Gafchromic film images, and graphs of UV irradiation duration and mean pixel values were plotted. There were reactions to UV‐A on both Gafchromic XR‐RV3 and XR‐SP2; those to UV‐B were moderate. However, UV‐C demonstrated few reactions with Gafchromic XR‐RV3 and XR‐SP2. From these results, irradiation with UV‐A may be able to correct nonuniformity errors. Uniform UV‐A irradiation of Gafchromic films with large areas is possible, and UV rays can be used as a substitute for X‐rays in the double exposure technique.PACS number: 87.53 Bn

Research on the UV-Curing Injection Molding

Based on the combination of UV curing and injection molding, a new concept named "chemical manufacturing" is proposed in this paper. A cylinder with a diameter of 6mm and a height of 10mm was used as the molding sample;A single factor analysis was used to determine the effects of the intensity of ultraviolet, the duration of ultraviolet irradiation and the distance between UVLED device and product surface on the formability of UV-curing injection molding. The experimental results showed that the intensity of UV radiation, the UV irradiation duration and the distance between UVLED device and product surface have a significant effect on the UV-curing molding of the product. With the increase of ultraviolet radiation intensity and UV irradiation duration, the forming quality of the products increases, while with the increase of the distance between UVLED device and product surface the forming quality of products declines.

Effect of nanoscale surface topography on low temperature direct wafer bonding process with UV activation

Low temperature direct wafer bonding is a promising technology for microelectromechanical systems (MEMS), sensors as well as silicon-on-insulator (SOI) materials. The bond quality is closely related to the wafer-bow, surface adhere energy and nanoscale surface topography. Effective surface activation and nanoscale surface topography evaluation is critical for the bonding process. For the low temperature silicon wafer direct bonding process with ultra violet (UV) light activation, surface nanoscale topography is modified and characterized before and after UV irradiation by the control of irradiation duration. The measured data of nanoscale topography by atomic force microscope (AFM) is evaluated by both bearing ratio and root-mean-square (RMS) approaches, from which the results are then correlated with the bond strength to understand the bonding process. It is shown that the bear ratio approach is more suitable for characterizing the surface roughness and optimizing the bonding process through the control of UV irradiation duration. The approach is also applicable to a wide variety of low temperature wafer bonding process where surface roughness is modified.

Effects of ultraviolet irradiation on the static and dynamic properties of neoprene rubbers

AbstractRubbers deteriorate when they are exposed to ultraviolet irradiation for long periods of time. By conducting a series of hardness measurements and simple tension tests, the static properties of neoprene rubbers before and after exposure to various durations of ultraviolet irradiation were first measured. It is found that the Shore A hardness and tensile modulus of neoprene rubbers after exposure to ultraviolet irradiation are increased but their elongation at break, tensile strength, and energy to break are significantly decreased. On the basis of a complex spring model of a vibration system, the dynamic shear properties of neoprene rubbers before and after exposure to different durations of ultraviolet irradiation were then determined from the experimental results of dynamic transmissibility tests. It is also found that the storage modulus, loss modulus, and loss factor of neoprene rubbers are drastically affected by the duration of ultraviolet irradiation they experienced. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Effects of UV irradiation on physico‐mechanical properties of EPDM/buckminsterfullerene composite

AbstractEthylene propylene diene rubber‐fullerene (EPDM/C60) composite, partially crosslinked by ultraviolet (UV) radiation, was prepared and characterized for crosslink density, mechanical properties and thermal behavior. FT‐IR analysis showed peak disappearance at 1688 cm−1, corresponding to the unsaturation of EPDM, and the appearance of new peaks relating to the formation of oxidation products of C60, such as epoxide, keto, aldehyde and carboxylic groups. Solubility studies demonstrated the dissolution of pristine EPDM in toluene even after a longer period of UV exposure, whereas EPDM/C60 composite became insoluble and/or swollen after 6 hr of UV exposure, indicating the formation of partial crosslinking between EPDM and C60. Differential scanning calorimetry (DSC) measurements revealed an increase in the glass transition temperature peak of UV‐cured EPDM. Thermogravimetric analysis (TGA) showed that UV exposure reduced the thermal decomposition temperature of EPDM/C60, pristine EPDM and dicumyl peroxide (DCP)‐cured EPDM. The modulus, tensile stress and elongation at break of EPDM/C60 composites were greatly influenced by the duration of UV irradiation. Comparison of UV‐cured EPDM/C60 composite with DCP‐cured EPDM confirmed the superior strength properties of the former system. Copyright © 2004 John Wiley & Sons, Ltd.

Experimental verification of photostability for free- and bound-amino acids exposed to γ-rays and UV irradiation

The photo-stability of simulated free and bound amino acids exposed to photon sources of 1.2–1.3 MeV γ-rays from a 60C° source and ultra-violet (UV) irradiation from a 10 eV deuterium lamp was examined. The free amino acids in aqueous solution were drastically decreased while the bound amino acids in aqueous solution were slightly decreased with the duration of γ-rays and UV irradiation. The apparent half-lives (t1/2) of bound serine and threonine under γ-rays irradiation were more than 10.6 and 27.9 times as stable as the free amino acids, respectively. The photo-stability of bound amino acids was greater than that of free amino acids under irradiation by high-energy photons. These results strongly suggest that bound, but not free, amino acids could be found in extraterrestrial environments. Radio- or photo-alteration processes are mainly decomposition pathways, with the production of secondary amino acids via decomposition of the α-carboxylic group; β-alanine and γ-aminobutyric acids, α-decarboxylation products of aspartic acid and glutamic acid, respectively, were detected.

Effects of Ultraviolet Irradiation on the Migratory Ability of Primordial Germ Cells (PGCs) in the Domestic Chicken

The effect of ultraviolet (UV) irradiation on the ability of primordial germ cells (PGCs) to migrate toward the gonadal ridge was investigated in the domestic chicken. When PGCs were irradiated with UV (254nm, 0.9±0.1μW/cm2) the extent of nuclear damage, as determined by the comet assay, was positively correlated with the duration of UV irradiation in the range from 0 to 60 seconds. However, no further increase in nuclear damage was detected when the duration of UV irradiation was extended from 60 to 120 seconds. To evaluate the migratory ability of PGCs after UV irradiation, 15 fluorescent-labeled PGCs were transferred into the vascular system of 2-day-old embryos and the fluorescent-labeled PGCs present in the gonads of recipient embryos were counted 5 days later. When the duration of UV irradiation was less than 60 seconds, the number of fluorescent-labeled PGCs found in the gonads of the recipient embryos exceeded the number of transferred PGCs. In conclusion, the ability of PGCs to migrate toward the developing gonad is retained after exposure to UV irradiation that causes apparent damage to the nucleus.

Effects of ultraviolet irradiation on genetical inactivation and morphological structure of sperm of the Japanese scallop, Patinopecten yessoensis

Effects of ultraviolet (UV) irradiation on genetic inactivation and morphological structure of sperms were examined in the scallop, Patinopecten yessoensis. Haploid gynogenesis of the scallop was successfully induced by 50–60 s UV irradiation of 720 μW cm −2 s −1. The fertilization rate apparently decreased with increasing irradiation time, and the development of the eggs fertilized with the genetically inactivated sperms terminated before reaching the D-shaped larvae stage. Scanning electron microscopy (SEM) showed clear destruction of the sperm acrosome and flagellum in the UV-irradiated sperms. As the duration of UV irradiation increased, the acrosome of sperms tended to suffer greater damage, until the sperms eventually lost their flagella. Abnormalities in these structures have appeared to account, at least in part, for the decline of the fertilization rate of eggs inseminated with UV-irradiated sperms.

Photograft polymerization of acrylate monomers and macromonomers on photochemically reduced PTFE films

The objective of this study was to explore and optimize the photograft polymerization of acrylate monomers and macromonomers upon premodified poly(tetrafluoroethylene) (PTFE) substrates, with a view toward applying these grafted materials as biomaterials. PTFE films were photochemically reduced by exposure to short wavelength ultraviolet (UV) light in the presence of the reducing agents, i.e., diphenyl ketyl radical anion, generated from a solution of benzophenone and sodium hydride in dimethylformamide (Noh et al., J. Polym. Sci. A, Polym. Chem., 35, 1499 (1997)). The photochemically reduced PTFE films were subsequently modified by photograft polymerization of acrylic acid, acrylamide, and poly(ethylene glycol) monoacrylate (PEG-Ac) by employing long wavelength UV irradiation with benzil dimethyl ketal as an initiator. The photochemically reduced PTFE films were good substrates for photograft polymerization, leading to surfaces with chemical compositions close to those of the respective homopolymers as determined by electron spectroscopy for chemical analysis. Photograft polymerization of PEG-Ac on the photochemically reduced surface was also explored with different concentrations (1, 2, 4, 6, and 8%; v/v) and molecular weights (200, 400, 1000, and 2000 g/mol) of PEG-Ac, different durations (5, 10, and 20 min) of long wavelength UV irradiation, and different concentrations (0.1, 0.2, 0.4, and 0.8%; v/v) of benzil dimethyl ketal. Higher concentrations and lower molecular weights of PEG-Ac generally led to more extensive photograft polymerization, whereas the concentration of benzil dimethyl ketal and duration of UV irradiation did not substantially influence the extent of photograft polymerization. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3467–3482, 1997

The Effect of Ultraviolet Irradiation on the Minority Carrier Recombination Lifetime of Oxidized Silicon Wafers

The effect of ultraviolet (UV) irradiation on the minority carrier recombination lifetime was studied using a laser‐microwave photoconductance (LM‐PCD) method for wafers oxidized at 700, 900, and 1000°C and for different oxidation times at these temperatures. For wafers oxidized at 1000°C, the lifetime was found to decrease with UV irradiation. For wafers oxidized at 700 and 900°C, the lifetimes could decrease or increase depending on the duration of oxidation and UV irradiation.

Optimization of physicomechanical properties of photopolymeric materials for optical data storage by treatment with high-frequency currents

We study the effect of the duration of ultraviolet irradiation of D-1 and D-2 photopolymerizable compositions on some physicomechanical properties of a photopolymeric material obtained in the process of photopolymerization. It is shown that these properties become most pronounced for a certain fixed duration of ultraviolet treatment and, hence, continuation of this process becomes unreasonable. The degree of conversion α of photopolymeric materials does not exceed 70%. Strength and some other characteristics of photopolymers can be improved by additional treatment of the material with high-frequency currents. This kind of treatment is characterized by lower power consumption and can be performed much faster than routine thermal treatment (by about two orders of magnitude).

Some Mechanochemical Considerations on the Numbers of Spins Induced by Ultraviolet Light

Abstract The number of spins/g (NOS) generated in a binary powder of glycolic acid and silica–alumina (SA) increased during ultraviolet (UV) irradiation. After stopping illumination, the NOS value was found to decrease up to a constant number of sping/g (CNS), which was remarkably greater than the NOS value obtained before UV irradiation. The CNS values, thus obtained, were influenced not only by the calcination temperature of SA (Tea) and by the atmosphere of storage, but also by the duration of UV irradiation (DI). The values of CNS obtained at a low Tca (below 400°C) were also influenced by the time interval between stopping shaking and the start of UV irradiation (ti). Values of NOS having attained CNS remained unchanged for a long period, but finally began to decrease. The duration of CNS (DCNS) was also affected by Tca, the atmosphere of storage, DI, and ti DCNS decreased when CNS increased, and became unchanged when CNS reached a constant value. Values of CNS and DCNS induced by UV light were also influenced by the size of SA particles and by the mechanical energy given by shaking or compressing. Such mechanochemical effects are available, at least for studying the generation mechanism of UV-induced surface activity, for an improvement of the reproducibility of physicochemical data obtained during or after UV irradiation, and for the method of obtaining materials of constant efficiency.