Doses Of UV Radiation Research Articles

Diabetic skin and UV light: Protection by antioxidants

Non-invasive biophysical methods were used to study the effect of antioxidant gels, which were prepared from Pinus halepensis bark extracts, vitamin C and water, on the skin of diabetic hairless mice irradiated with UV radiation of 1 and 2 minimal erythemal doses (MEDs). The calculated transepidermal water loss (TEWL) for diabetic mice was found to be fivefold higher on day 11 after irradiation, and in all cases, the TEWL values converged to their initial values on day 21. Both pinus and vitamin C gels inhibited the dehydration of the skin, while water gels did not show similar protection. At low dose of UV-irradiation (1 MED), vitamin C gels showed the best hydration, while by doubling the UV dose, pinus gels induced significant skin-protective effects. Upon irradiation, the mice treatment with pinus gel showed diminished inflammation in comparison with the other gels. Pinus also inhibited the hyperkeratosis of skin. As expected, 2 MEDs caused greater skin damage, such as inflammation, dryness, oxidative stress and rides (aging) compared to the damage induced by 1 MED.

Karcinomi kože uzrokovani solarnim zračenjem kao profesionalna bolest

SUMMARY: The aim of this review article is to point out to the danger for workers who, by the nature of their occupation, spend most of their working hours outdoor and are exposed to sunlight that increases their risk of skin cancer. Exposure to sunlight during outdoor work increases the average annual dose of UV radiation for 4-5 times compared to people who do not work in the sun, which in outdoor workers significantly increases the risk for the occurrence of actinic keratosis, basal-cell skin cancer and squamous-cell skin cancer. It is considered that the risk for the occurrence of these disorders is doubled if the total lifetime UV radiation dose for persons occupationally non exposed to sun (130 SED annually) is exceeded by 40%. In the EU countries, including Croatia, the introduction of UV radiation personal dosimetry for outdoors workers is in progress. In order to prevent skin cancer caused by occupational UV exposure, it is necessary to implement preventive measures for outdoor workers. Minimum standards for prevention at the EU level include the application of personal protection measures (sunglasses, headgear, clothing, creams with sun protective factor) and health and safety educational programs implemented in the curricula of secondary high schools, and provided to workers at risky workplaces. Skin cancers or multiple actinic keratosis can be recognized as an occupational disease if: 1) diagnosis of squamous-cell skin cancer or basal-cell skin cancer or multiple actinic keratosis (minimum 6 changes) is histologically confirmed; 2) the changes are expressed in occupationally exposed areas of the skin; 3) the history of the disease reveals sufficient occupational exposure to UV radiation.

Ultraviolet radiation modulates C:N stoichiometry and biomass allocation in Fagus sylvatica saplings cultivated under elevated CO2 concentration

Under the conditions of ongoing climate change, terrestrial ecosystems will be simultaneously exposed to a permanent rise in atmospheric CO2 concentration and increasing variability of such environmental factors as temperature, precipitation, and UV radiation. This will result in numerous interactions. The interactive effects caused by exposure to such multiple environmental factors are not yet well understood. We tested the hypotheses that enhanced UV radiation reduces the stimulatory effect of elevated CO2 concentration on plant biomass production and that it alters biomass allocation in broadleaved European beech (Fagus sylvatica L.) saplings. Our results after 2 years of exposure confirmed interactive effects of CO2 concentration and UV radiation on biomass production, and particularly on biomass allocation to roots and aboveground biomass. The strongest stimulatory effect of elevated CO2 on aboveground biomass and roots was found under ambient UV radiation, while both low and high UV doses reduced this stimulation. Nitrogen content in the roots and the distribution of nitrogen among leaves and roots were also significantly affected by interaction of CO2 concentration and UV radiation. The observed changes in leaf and root C:N stoichiometry were associated with altered morphological traits, and particularly with a change in the proportion of fine roots. As the biomass allocation and especially the proportion of fine roots can play an important role in effective water and nutrient use and acclimation to future climates, it is essential to obtain a deeper understanding of the links between C:N stoichiometry and biomass accumulation.

Nitrogen oxide removal from simulated flue gas by UV-irradiated electrolyzed seawater: Efficiency optimization and pH-dependent mechanisms

UV/chlorine has attracted much attention in flue gas and water treatment fields in recent years. However, only a few studies highlighted gas pollutants removal performance of UV/chlorine method in real water. In this study, nitrogen oxide (NOx) removal using UV-irradiated electrolyzed seawater (UV/electrolyzed seawater) was explored under simulated seawater environment in a semi-batch photochemical reactor. Comparison experiments between UV/H2O2 and UV/chlorine in both freshwater and seawater systems were performed. Results showed that NO removal efficiency in UV/chlorine freshwater system was higher than those in UV/chlorine seawater system, due to radical scavenging effects of water matrices in seawater. Several strong reactive radicals (e.g., OH, Cl, OCl, ClOH−) yielded from UV/chlorine system were considered to contribute to NOx removal, among which the role of OH radical was confirmed by radical-trapping experiments. The alkalinity of the seawater adversely impacted contributions of these reactive radicals to NOx removal, which caused a sharp drop in NOx removal efficiencies. Comparatively, the chloride ion in seawater had slight influences on NOx removal efficiencies of UV/electrolyzed seawater. Then, optimization of NOx removal efficiencies against three key variables (active chlorine concentration, UV irradiation dose, and initial pH) was investigated in simulated seawater using Design Expert Software. A regression model of NOx removal efficiency was obtained with satisfactory accuracy. Results indicated that active chlorine concentration and UV irradiation dose significantly influenced NOx removal efficiencies, compared with pH effects. Furthermore, NOx removal mechanisms involved in reactive radicals were discussed for UV/electrolyzed seawater method. Due to pH-dependent characteristics of both active chlorine species and carbonate species in electrolyzed seawater, NOx removal pathways by UV/electrolyzed seawater were different as the environment changed from acid to alkalinity.

6-Formylindolo[3,2-b]carbazole (FICZ) is a Very Minor Photoproduct of Tryptophan at Biologically Relevant Doses of UVB and Simulated Sunlight.

Exposure to solar UV is at the origin of numerous photodegradation pathways in biomolecules. Tryptophan is readily modified by UVB radiation into ring-opened and oxidized photoproducts. One of them, 6-formylindolo[3,2-b]carbazole (FICZ), has been extensively studied in the recent years because it very efficiently binds to AhR, a major factor in numerous biologic processes, such as metabolism of xenobiotics. Unfortunately, little information is available on the actual yield of FICZ upon exposure to low and biologically relevant doses of UV radiation. In the present work, we used a sensitive and specific HPLC-tandem mass spectrometry assay to quantify a series of photoproducts induced by UVB and simulated sunlight (SSL) in solutions of tryptophan. FICZ represented only a minute amount of the photoproducts (0.02 and 0.03%, respectively). Experiments were repeated in culture medium where the yield of FICZ was also found to be very low, even when Trp was added. Last, no FICZ could be detected in cytosolic fractions of cultured cells exposed to SSL. Altogether, the present results show that FICZ is a very minor photoproduct and that it cannot be considered the only endogenous photoproduct responsible for the induction of AhR-dependent responses in UV-irradiated cells.

Tuning of luminescent properties of Zn1-xMgAl10O17:Eux nano phosphor

The Zn1-xMgAl10O17:Eux2+ (x = 0.01–0.4) nano phosphors were prepared successfully using the combustion route by employing urea as a fuel. The structural, microstructural, thermal, optical and luminescent properties were measured on the samples. The nano phosphors were found to be of surface area (∼13.92 m2/g) and insulators of the band gap (∼5.24eV). Photoluminescence properties on the samples were characterized by excitation (λex. = 340 nm) and emission (λem. = 440 nm) spectra. The phosphors showed strong blue luminescence (440 nm-460 nm) as well as showed weak luminescence in 577 nm, 589 nm, 596 nm, and 615 nm in the orange-red region, which are attributed to 4f65 d1→4f7 and 5D0→7Fj (j = 0, 1,…) transitions of the Eu (II) and Eu (III) ions respectively. The tuning of this blue luminescent properties as compared to the earlier reported red luminescence has been achieved. Thermo-luminescence glow curve recorded under 10-minute dose of UV (254 nm) radiation have been used to calculate the kinetic parameters and the activation energy of the nano phosphors by using the Chens-equation. The TL emission spectra of the Zn0.99MgAl10O17:Eu0.01 phosphor showed the characteristic Eu2+ emission peaks ∼450 nm (blue) originating from the transitions 4f65 d1→4f7. The possible mechanism of the PL and TL of blue light emitting phosphor are also discussed.

Microhardness of poly(methyl methacrylate)-multiwalled carbon nanotubes composites: Effect of ultraviolet irradiation

Understanding the mechanical behavior of polymer matrix composites under the service conditions is of practical importance to improve structural durability and reliability. In this work, we study the microhardness of poly(methyl methacrylate)-multiwalled carbon nanotubes (PMMA-MWCNTs) composite as a function of the fraction of MWCNTs and the irradiation of ultraviolet (UV) light in a temperature range of 50–80 °C. Increasing temperature, heating time, and the weight fraction of MWCNTs causes the increase of the microhardness of the PMMA-MWCNT composite, while increasing the UV-irradiation dose causes the decrease of the microhardness of the PMMA-MWCNT composite. A first-order kinetic process is proposed to analyze the variation of the microhardness of the PMMA-MWCNT composite with time. The activation energy for the first-order kinetic process increases with increasing the weight fraction of MWCNTs, and decreases with increasing the UV-irradiation dose. The temperature dependence of the microhardness of the PMMA-MWCNT composite at equilibrium state follows the van't Hoff relation.

Order-Disorder transition of carboxyl terminated chains in polydiacetylenes vesicles probed by second harmonic generation and two-photon fluorescence

To understand and control the interfacial properties of polydiacetylenes (PDAs) vesicles with π-conjugated backbone is very important for their colorimetric sensing of chemical and biological targets. In this work, we adopted 10, 12-pentacosadiynoic acid (PCDA) as the model molecule to prepare PDAs vesicles in aqueous solution with different forms (from monomer to blue-to-purple-to-red phase) by controlling the UV irradiation dose. The variations of the interfacial conformation of PDAs vesicles during chromatic transitions were inspected by the adsorption behaviors of probe molecules (4-(4-diethylaminostyry)-1-methylpyridinium iodide, D289) on vesicle surface with surface-specific second harmonic generation (SHG) and zeta potential measurements. Resonant SHG signal from D289 adsorbed on vesicle surface attenuated sharply, and the adsorption free energy as well as the corresponding two-photon fluorescence signal decreased slightly in chromatic transitions. While, the change in the surface density of the adsorbed D289 molecules for PDAs vesicles with different forms was relatively small as estimated from zeta potential measurements. The attenuation of the SHG intensity was thus attributed to the overall order-disorder transition and the changed orientation of D289 molecules caused by the gradual distortion of carboxyl head group driven by backbone perturbation.

Conducting and stretchable nanometer-thin gold/thiol-functionalized polydimethylsiloxane films

Future low-voltage dielectric elastomer transducers (DETs), based on nanometer-thin elastomer membranes, will rely on soft and compliant electrodes with reasonable electrical conductivity and sound adhesion to the elastomer. State-of-the-art adhesion promoters, including nanometer-thin Cr/Ti films, result in defects for applied areal strains larger than 3% and lead to increases in the stiffness of DETs. To generate forces in the Newton range, these low-voltage DETs have to be stacked in thousands of layers. Herein, we present a compliant electrode, which consists of gold bonded covalently to thiol-functionalized polydimethylsiloxane (SH-PDMS) films. The membranes were fabricated using molecular beam deposition and in situ and/or subsequent ultraviolet light (UV) radiation. Peel-off tests demonstrate the expected strong binding of Au to the SH-PDMS network, with this highly stretchable Au/SH-PDMS layer capable of withstanding strains of at least 60%, without losing conductivity. Optical micrographs show signs of cracks for strained pure Au and Au/Cr electrodes but not for the Au/SH-PDMS layer. The mechanical properties and adhesion forces of Au/SH-PDMS were extracted by means of atomic force microscopy (AFM), using a spherical Au tip coated with methyl groups (CH3). The elastic modulus of ( 12 ± 9 ) MPa increased slightly against the 20-nm-thin Au/PDMS example, but it can be tailored by the cross-linking density of Au/SH-PDMS via the UV irradiation dose. Unloading nanoindentation curves revealed pull-off forces between the CH3-functionalized AFM tip and the Au/SH-PDMS layer at the time of separation. For Au/SH-PDMS, the spectral distribution of pull-off forces exhibits repulsive forces with the CH3 groups of the PDMS network as well as adhesive forces resulting from interactions with the nanometer-sized Au clusters. This approach provides the means to bind gold clusters homogenously within the SH-PDMS film. Such compliant electrodes are the prerequisite for fabricating low-voltage DETs that can be stretched by more than 50%.

Ultraviolet radiation exposure triggers neurokinin-1 receptor upregulation in ocular tissues in vivo

The purpose of this study was to investigate the neurokinin receptor-1 (NKR-1) protein expression in ocular tissues before and after supra-cataract threshold ultraviolet radiation (UVR-B peak at 312 nm) exposure in vivo in a mouse model.Six-week-old C57Bl/6 mice were unilaterally exposed to a single (2.9 kJ/m2) and an above 3-fold UVR-B cataract threshold dose (9.4 kJ/m2) of UVR. UVR-exposure (λpeak = 312 nm) was performed in mydriasis using a Bio-Spectra exposure system. After latency periods of 3 and 7 days, eyes were fixed in 4% paraformaldehyde, embedded in paraffin, sectioned and stained with fluorescence coupled antibody for NKR-1 and DAPI for cell nuclei staining. Control animals received only anesthesia but no UVR-exposure. Cataract development was documented with a Leica dark-field microscope and quantified as integrated optical density (IOD).NKR-1 is ubiquitously present in ocular tissues. An above 3-fold cataract threshold dose of UV-radiation induced NKR-1 upregulation after days 3 and 7 in the epithelium and endothelium of the cornea, the endothelial cells of the iris vessels, the pigmented epithelium/stroma of the ciliary body, the lens epithelium, pronounced in the nuclear bow region and the inner plexiform layer of the retina. A significant upregulation of NKR-1 could not be provoked with a single cataract threshold dose (2.9 kJ/m2 UVR-B) ultraviolet irradiation. All exposed eyes developed anterior subcapsular cataracts.Neurokinin-1 receptor is present ubiquitously in ocular tissues including the lens epithelium and the nuclear bow region of the lens. UV-radiation exposure to an above 3-fold UVR-B cataract threshold dose triggers NKR-1 upregulation in the eye in vivo. The involvement of inflammation in ultraviolet radiation induced cataract and the role of neuroinflammatory peptides such as substance P and its receptor, NKR-1, might have been underestimated to date.

DNA double-strand breaks promote endoreduplication in radish cotyledon.

DSBs differently affect endoreduplication and organ size in radish cotyledons and hypocotyls in different light conditions, suggesting that DSBs-mediated endoreduplication varies based on different developmental and environmental cues. Endoreduplication induced by DNA double strand breaks (DSBs) in Arabidopsis thaliana roots and cultured cells has been reported in recent years. In this study, we investigated whether DSBs-mediated endoreduplication also occurs in other tissues, such as cotyledons and hypocotyls of radish (Raphanus sativus var. longipinnatus) plants. To induce DSBs, UV irradiation and Zeocin treatment were applied to in vitro-cultured radish seedlings, and ploidy distribution of the treated tissues was analyzed by flow cytometry. Consequently, frequencies of the higher ploidy (8C) cells and cycle values in the cotyledon tissues increased with increasing doses of UV irradiation and concentrations of Zeocin, irrespective of light conditions. UV-stimulated endoreduplication was also observed in four Brassica species. In hypocotyls, UV treatments decreased the frequencies of higher ploidy (32C) cells and cycle values in dark-grown seedlings, whereas Zeocin treatments increased the frequencies of higher ploidy (16C and 32C) cells and cycle values in light- and dark-grown seedlings. Among the treatments, organ sizes did not simply correlate with cycle values. The effects of treatments on endoreduplication and organ size differed based on organ and light conditions, indicating that DSBs-mediated endoreduplication may involve a multifaceted response to different developmental and environmental cues.

Removal of Waterborne Pathogen by Nanomaterial-Membrane Coupling System.

The waterborne pathogenic viruses threaten human health. And the nanomaterial-membrane coupling system is promising in virus removal. In this study, phage MS2 was selected as the model virus to investigate the removal of virus with the coupling system. Results revealed that commercial nano TiO2 (Degussa Aeroxide P25) showed both of excellent adsorption and photocatalysis performance for virus removal compared with nano ZnO, nano Fe3O4, carbon nanotube, graphene, nano Ni and Nano TiO2 (anatase). In P25 photocatalysis process, the removal efficiency of phage MS2 increased with the increase of P25 concentration (0~1000 mg L-1), virus initial concentration (102~106 PFU mL-1), UV irradiation doses (5~120 mJ cm-2) and UV light intensity (0.126~0.742 mW cm-2). However, when the P25 concentration increased to over 1000 mg L-1, the virus removal efficiency would remain stable with the increase of P25 concentration. The nanomaterial-membrane coupling system showed excellent performance for virus removal, which was mainly attributed to the adsorption and photocatalysis of P25, and the intercept of membrane. When the P25 concentration was 100 mg L-1, UV irradiation dose was 20 mJ cm-2 and transmembrane pressure was 20 kPa, the phage MS2 removal efficiency could be up to 100%.

Analysis of Erythemal UVB Dose Received Inside a Car in Valencia, Spain

Continuous exposures to ultraviolet radiation can lead to harmful effects on human skin. Professional drivers may spend more than 8h per day inside a vehicle. This study describes an analysis of the UVER (erythemal ultraviolet radiation) received by a driver and passenger inside a vehicle. A three-door Peugeot 206 was used for the study. VioSpor Blue Line dosimeters (with a response profile close to that of human skin) were used to measure the erythematic dose of UV radiation (able to produce erythema on human skin). Four dosimeters were placed in the driver's position and another four in the passenger's position. Daily irradiance was analyzed for a day in April using PMA radiometers. The measurements were obtained on relatively clear days from February to December 2009 between 9:30 A.M. and 3 P.M. Additionally, a prediction was made of the time required to produce an erythema on the driver's skin. UVER exposure, in some of the driver's positions, exceeds the Exposure Limits given by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). Skin protection measures should be taken into account by professional drivers to prevent the harmful effects of UVER radiation.

Fungicidal Effects of Ultraviolet Light (254 nm) Irradiation on Contaminated Museum Packing and Storing Materials

In storage of modern museums, collections are packed and stored with acid-free paper-based materials for keeping safe and stable conditions. Direct contact of fungal contaminated packing and storing materials with the collections is concerned about expanding of infection in storage facilities. In this study, fungicidal effects of UV light irradiation on the materials such as archival board and Japanese tissue paper contaminated with Penicilliun commune and Chaetomium globosum were tested. The analyzed materials were divided into two groups; Group 1 was examined with 20 μl of spore suspensions of fungi (106 cfu/ml) ; and Group 2 was tested on Czapek- Dox agar medium modified without sugar and inoculated with 100 μl of the spore suspensions of fungi (106 cfu/ml) . Six doses of UV irradiation were examined on Group 1 and five doses on Group 2 in addition to control. The assessment was done by using 1) adenosine triphosphate (ATP) bioluminescence assay and double staining to determine the cell viability; 2) observation under light microscope to evaluate morphophysiological change of tested fungi (spores and hyphae) . Because of the thinness and high transparency of tissue paper, UV irradiations were highly efficient to fungicide its fungal contamination compared with archival board. In spite of the high resistance of C. globosum spores, the rate of growth was slow, and with a little amount of perithecia or fruiting bodies and a high amount of ycelium (which damaged rapidly through UV irradiation) . This may be due to a low relative humidity of the incubation environment. Minimum dosage of UV irradiation with fungicidal effectiveness against all fungal contamination was estimated as 118 J/cm2.

Improved Procedure for Induction of the Androgenetic Doubled Haploids in Zebrafish.

Androgenesis is useful for induction of doubled haploids from male genetic resources and contributes to the restoration of individuals from cryopreserved sperm. Here, we determined the suitable conditions for egg in vitro preservation and the suitable dose of UV irradiation for genetic inactivation of the egg nucleus, and established an improved procedure for induction of androgenetic-doubled haploids in zebrafish. The suitable solution for egg preservation was evaluated by the fertilization rate using different types of solutions or conditions. Hank's solution with 0.5% bovine serum albumin (pH8.0) was suitable for the preservation of zebrafish eggs. In addition, we discovered an improvement of fertilization rates by temporal preservation of ovulated eggs in the suitable solution. UV irradiation of eggs at 50-75 mJ/cm2 induced haploid embryos. Microsatellite genotyping using eight loci revealed the paternity and homozygosity of the putative androgenetic doubled haploids. The yield rate of androgenetic doubled haploids, which were induced by UV irradiation and heat shock, ranged from 0.4% to 10.7%.

Combining sun-based technologies (microalgae and solar disinfection) for urban wastewater regeneration

Solar disinfection (SODIS) of urban wastewater can be a suitable technology for improving the microbiological quality of reclaimed water as a complement to other extensive and environmentally friendly technologies such as microalgae biotreatment. The objective of this work is to evaluate the feasibility of incorporating the SODIS technology at the end of a pilot scale urban wastewater treatment plant (WWTP) where the processes are based on microalgae biotechnology and comprising three Upflow Anaerobic Sludge Blanket (UASB, 20m3 each one) reactor, six High Rate Algal Ponds (HRAP, 32m2 each one), and a Dissolved Air Flotation (DAF, 1m3) unit. E. coli concentration was monitored at the effluent of the different units (UASB, HRAP, DAF) of the pilot WWTP. The efficiency of the SODIS process was studied for the inactivation of three of the commonly employed indicator microorganisms (Escherichia coli, Enterococcus spp. and Clostridium perfringens) using a compound parabolic collector (CPC) for five months under various conditions of irradiance and temperature.E. coli and Enterococcus spp. were more effectively disinfected by the SODIS unit (2.9 and 2.5 logarithms of reduction on average, respectively) than by the HRAP (2 and 1.1) or the DAF (0.9 and 0.1). On the contrary, the DAF technology achieved better reduction rates of C. perfringens (1.7) than the SODIS (0.9) and the HRAP (0.1). No regrowth of any microorganisms was detected during dark storage after the SODIS treatment.Incorporating a SODIS unit after the non-conventional WWTP processes substantially increases the possibilities for reuse of the treated water after receiving a cumulative UV radiation dose of 25W·h/m2 (50min of normalized time of solar illumination). The surface requirement of the SODIS equipment would be 3.5 times smaller than the HRAP's surface.

Stable Nuclei of Nucleoprotein Filament and High ssDNA Binding Affinity Contribute to Enhanced RecA E38K Recombinase Activity

RecA plays central roles in the homologous recombination to repair double-stranded DNA break damage in E. coli. A previously identified recA strain surviving high doses of UV radiation includes a dominant RecA E38K mutation. Using single-molecule experiments, we showed that the RecA E38K variant protein assembles nucleoprotein filaments more rapidly than the wild-type RecA. We also used a single-molecule fluorescence resonance energy transfer (smFRET) experiment to compare the nucleation cluster dynamics of wild-type RecA and RecA E38K mutants on various short ssDNA substrates. At shorter ssDNA, nucleation clusters of RecA E38K form dynamically, while only few were seen in wild-type RecA. RecA E38K also forms stable nuclei by specifically lowering the dissociation rate constant, kd. These observations provide evidence that greater nuclei stability and higher ssDNA binding affinity contribute to the observed enhanced recombination activity of the RecA E38K mutant. Given that assembly of RecA nucleoprotein filaments is the first committed step in recombinational repair processes, enhancement at this step gives rise to a more efficient recombinase.

USING MIXED GAMMA AND ULTRAVIOLET RADIATION FOR DISINFESTIATION OF IRAQI DATES FRUIT FROM EPHESTIA CAUTELLA

Fig moth E. cautella, considered the most serious pests infest dates and cause economic losses in the field and warehouses in Iraq which produces between 600-700 thousand tons of dates annually. In order to reduce this damage, different pest control methods are used, and mixed radiation considered one of the newest and innovative way to control the Moth that attack stored dates. This research has been done in Nuclear Laboratory of Edu. For pure Sci. / Ibn al-Haitham in 2016, three boxes for each irradiation dose, each one contain 10 date fruits. Dates. Zahdi variety artificially infested by eggs of Ephestia cautella. Eggs and larvae of insect exposed to different doses of gamma radiation on 5 periods for each dose separated by 5 min for each period of irradiation along with constant dose of UV radiation, 15min for all treated samples. Irradiated dates stored at 19Co for 40 and 30 day for eggs and larvae respectively. Results showed that the mixed radiation technique were effective for eliminating the insect and keeping the dates preserved with high quality A dose of 106Gy and 298Gy of gamma required for 100% of eliminating eggs and larvaes respectively. Physical and chemical characteristics did not changed as a result of irradiation.

Thermoluminescence of LaAlO3:C crystals grown by different mixing methodologies applied to UV dosimetry

In this paper, thermoluminescence (TL) properties such as glow curves analysis, dose response linearity and some dosimetric characteristics of pure and carbon doped lanthanum aluminate (LaAlO3) produced by different syntheses using the solid state reaction method are investigated, after exposure to different UV radiation doses. The effect of different syntheses on the TL glow curves structures is also investigated and discussed. TL glow-curve deconvolution (CGD) methods and the Chen’s peak shape methods were used to analyze the sets of TL glow curves. The kinetic parameters of TL single peaks were computed. Additionally, the life times (τ) of electrons in trap for all samples were determined and calculated. A good linear dose response over the dose range from 0.21 to 1.26mJ/cm2 has been attributed to both samples (B and C).

On transient climate change at the Cretaceous−Paleogene boundary due to atmospheric soot injections

Climate simulations that consider injection into the atmosphere of 15,000 Tg of soot, the amount estimated to be present at the Cretaceous-Paleogene boundary, produce what might have been one of the largest episodes of transient climate change in Earth history. The observed soot is believed to originate from global wildfires ignited after the impact of a 10-km-diameter asteroid on the Yucatán Peninsula 66 million y ago. Following injection into the atmosphere, the soot is heated by sunlight and lofted to great heights, resulting in a worldwide soot aerosol layer that lasts several years. As a result, little or no sunlight reaches the surface for over a year, such that photosynthesis is impossible and continents and oceans cool by as much as 28 °C and 11 °C, respectively. The absorption of light by the soot heats the upper atmosphere by hundreds of degrees. These high temperatures, together with a massive injection of water, which is a source of odd-hydrogen radicals, destroy the stratospheric ozone layer, such that Earth's surface receives high doses of UV radiation for about a year once the soot clears, five years after the impact. Temperatures remain above freezing in the oceans, coastal areas, and parts of the Tropics, but photosynthesis is severely inhibited for the first 1 y to 2 y, and freezing temperatures persist at middle latitudes for 3 y to 4 y. Refugia from these effects would have been very limited. The transient climate perturbation ends abruptly as the stratosphere cools and becomes supersaturated, causing rapid dehydration that removes all remaining soot via wet deposition.