Ultraviolet Radiation Protection by a Beach Umbrella

A beach umbrella intercepts all direct UV irradiance, but only part of the diffuse component. Using a simple sky view factor model, we have determined the fraction of the hemispheric diffuse irradiance that is not intercepted by the umbrella. Assuming a sensor at the surface and close to the center of the umbrella, isotropic diffuse irradiance and for an umbrella of 80 cm radius and 100 cm high, our results show that approximately 34% of the incident horizontal irradiance is not intercepted by the umbrella. These results agree with irradiance measurements conducted with and without the umbrella. The model is next extended to examine receipt of UV radiation by a human figure in a vertical position, either standing or sitting.     

Kinetics of Photosynthetic Response to Ultraviolet and Photosynthetically Active Radiation in Synechococcus WH8102 (CYANOBACTERIA)

The picoplanktonic cyanobacteria, Synechococcus spp., (Nägeli) are important contributors to global ocean primary production that can be stressed by solar radiation, both in the photosynthetically active (PAR) and ultraviolet (UV) range. We studied the responses of PSII quantum yield (active fluorescence), carbon fixation (¹⁴C assimilation) and oxygen evolution (membrane inlet mass spectrometry) in Synechococcus WH8102 under moderate UV and PAR. PSII quantum yield decreased during exposure to moderate UV and UV+PAR, with response to the latter being faster (6.4 versus 2.8 min, respectively). Repair processes were also faster when UV+PAR exposure was followed by moderate PAR (1.68 min response time) than when UV was followed by very low PAR (10.5 min response time). For the UV+PAR treatment, the initial decrease in quantum yield was followed by a 50% increase (“rebound”) after 7 min exposure, showing an apparent photoprotection induction. While oxygen uptake increased with PAR, it did not change under UV, suggesting that this oxygen‐dependent mechanism of photoprotection, which may be acting as an electron sink, is not an important strategy against UV. We used propyl gallate, an antioxidant, to test for plastid terminal oxidase (ptox) or ptox‐like enzymes activity, but it caused nonspecific and toxic effects on Synechococcus WH8102.     

Effect of Protective Measures on Eye Exposure to Solar Ultraviolet Radiation

In this study, ocular biologically effective exposure to solar ultraviolet radiation (UVBE) is investigated with six kinds of sun protective measures (spectacle lenses, sunglasses, cap, bonnet, straw hat and under parasol). Ocular UV exposure measurements were performed on manikins during the summer period in Shenyang city (41.64° N, 123.50° E, 66 m a.s.l.), China. The measurements include the ocular UV exposure of an unprotected eye and the ambient UV as a control concurrently. Based on the relative spectral weighting factors of the International Commission on Non‐Ionizing Radiation Protection (ICNIRP), the ocular biologically effective UV is calculated and compared with the 8‐h exposure limits of ICNIRP (30 J m^?2). The UV index (UVI) of the measurement days is 0–8, and the 8‐h (8:00–16:00 China Standard Time, CST) cumulated UVBE of the unprotected eye is 452.0 J m^?2. The 8‐h cumulated UVBE of the eye with spectacle lenses, sunglasses, cap, bonnet, straw hat and under parasol are 364.2, 69.1, 51.4, 49.0, 56.8 and 110.2 J m^?2, respectively. Importantly, it should be noted that the eye could be exposed to risk despite protective measures. The 8‐h cumulated UVBE of the eye with protection is ca 1.6–15.1 times the exposure limit, respectively. As indicated in the present study, during summer months, high exposure to the sun for more than 30 min without eye protection and more than 1 h with eye protection is not advisable. The protection measures could effectively reduce the UVBE reaching the eye, yet there is still a high degree of risk when compared with the ICNIRP 8‐h exposure limits.     

Bacterial Inactivation by Solar Ultraviolet Radiation Compared with Sensitivity to 254 nm Radiation

Our goal was to derive a quantitative factor that would allow us to predict the solar sensitivity of vegetative bacterial cells to natural solar radiation from the wealth of data collected for cells exposed to UVC (254 nm) radiation. We constructed a solar effectiveness spectrum for inactivation of vegetative bacterial cells by combining the available action spectra for vegetative cell killing in the solar range with the natural sunlight spectrum that reaches the ground. We then analyzed previous studies reporting the effects of solar radiation on vegetative bacterial cells and on bacterial spores. Although UVC-sensitive cells were also more sensitive to solar radiation, we found no absolute numerical correlation between the relative solar sensitivity of vegetative cells and their sensitivity to 254 nm radiation. The sensitivity of bacterial spores to solar exposure during both summer and winter correlated closely to their UVC sensitivity. The estimates presented here should make it possible to reasonably predict the time it would take for natural solar UV to kill bacterial spores or with a lesser degree of accuracy, vegetative bacterial cells after dispersion from an infected host or after an accidental or intentional release.     

Estimation of Daily Ultraviolet Radiation in Beijing Using a Semiempirical Method

This study proposes a semiempirical method to reconstruct daily ultraviolet (UV) radiation from global solar (G) radiation measurements using a radiative transfer model. The attenuation ratio and cloud modification factors are calculated based on measured and simulated data under cloudless‐sky conditions. A reconstruction method of UV radiation is established using cloud modification factors; based on comparisons among reconstructions and measurements, the reconstruction model is demonstrated to offer high resolution. The bias errors for daily measured and reconstructed UV radiation are maintained within ±20%, the mean absolute bias error (mabe) is 7.7% and the root mean square error (rmse) is 9.7%. Furthermore, the model performance and transferability were tested by comparison with a simple empirical model in Beijing, Eerduosi and Hailun. A comparison of the measured and estimated UV values for the two methods in the aforementioned three locations revealed that smaller mabe and rmse were observed in our method, with both of these values in the three locations being less than 14%. Thus, a better applicability and transferability has been confirmed. The results and analysis should contribute to improving the knowledge about actual UV climate characteristics.     

Measuring Exposure to Solar Ultraviolet Radiation Using a Dosimetric Technique: Understanding Participant Compliance Issues

Personal ultraviolet dosimeters have been used in epidemiological studies to understand the risks and benefits of individuals' exposure to solar ultraviolet radiation (UVR). We investigated the types and determinants of noncompliance associated with a protocol for use of polysulphone UVR dosimeters. In the AusD Study, 1002 Australian adults (aged 18–75 years) were asked to wear a new dosimeter on their wrist each day for 10 consecutive days to quantify their daily exposure to solar UVR. Of the 10 020 dosimeters distributed, 296 (3%) were not returned or used (Type‐I noncompliance) and other usage errors were reported for 763 (8%) returned dosimeters (Type‐II noncompliance). Type‐I errors were more common in participants with predominantly outdoor occupations. Type‐II errors were reported more frequently on the first day of measurement; weekend days or rainy days; and among females; younger people; more educated participants or those with outdoor occupations. Half (50%) the participants reported a noncompliance error on at least 1 day during the 10‐day period. However, 92% of participants had at least 7 days of usable data without any apparent noncompliance issues. The factors identified should be considered when designing future UVR dosimetry studies.     

Exposure of Arctic Field Scientists to Ultraviolet Radiation Evaluated Using Personal Dosimeters

During July 2000 we used an electronic personal dosimeter (X-2000) and a biological dosimeter (Deutsches Zentrum für Luft- und Raumfahrt: Biofilm) to characterize the UV radiation exposure of arctic field scientists involved in biological and geological fieldwork. These personnel were working at the Haughton impact structure on Devon Island (75 degrees N) in the Canadian High Arctic under a 24 h photoperiod. During a typical day of field activities under a clear sky, the total daily erythemally weighted exposure, as measured by electronic dosimetry, was up to 5.8 standard erythemal dose (SED). Overcast skies (typically 7-8 okta of stratus) reduced exposures by a mean of 54%. We estimate that during a month of field activity in July a typical field scientist at this latitude could potentially receive approximately 80 SED to the face. Because of body movements the upper body was exposed to a UV regimen that often changed on second-to-second time-scales as assessed by electronic dosimetry. Over a typical 10 min period on vehicle traverse, we found that erythemal exposure could vary to up to 87% of the mean exposure. Time-integrated exposures showed that the type of outdoor field activities in the treeless expanse of the polar desert had little effect on the exposure received. Although absolute exposure changed in accordance with the time of day, the exposure ratio (dose received over horizontal dose) did not vary much over the day. Under clear skies the mean exposure ratio was 0.35 +/- 0.12 for individual activities at different times of the day assessed using electronic dosimetry. Biological dosimetry showed that the occupation was important in determining daily exposures. In our study, scientists in the field received an approximately two-fold higher dose than individuals, such as medics and computer scientists, who spent the majority of their time in tents.     

Different Photosynthetic Responses of Pyropia yezoensis to Ultraviolet Radiation Under Changing Temperature and Photosynthetic Active Radiation Regimes

Macroalgae play a crucial role in coastal marine ecosystems, but they are also subject to multiple challenges due to tidal and seasonal alterations. In this work, we investigated the photosynthetic response of Pyropia yezoensis to ultraviolet radiation (PAR: 400–700 nm; PAB: 280–700 nm) under changing temperatures (5, 10 and 15°C) and light intensities (200, 500 and 800 μmol photons m^?2 s^?1). Under low light intensity (200 μmol photons m^?2 s^?1), P. yezoensis showed the lowest sensitivity to ultraviolet radiation, regardless of temperature. However, higher temperatures inhibited the repair rates (r) and damage rates (k) of photosystem II (PSII) in P. yezoensis. However, under higher light intensities (500 and 800 μmol photons m^?2 s^?1), P. yezoensis showed higher sensitivity to UV radiation. Both r and the ratio of repair rate to damage rate (r:k) were significantly inhibited in P. yezoensis by PAB, regardless of temperature. In addition, higher temperatures significantly decreased the relative UV‐inhibition rates, while an increased carbon fixation rate was found. Our study suggested that higher light intensities enhanced the sensitivity to UV radiation, while higher temperatures could relieve the stress caused by high light intensity and UV radiation.     

Identification of the Flavonoid Glycosides that Accumulate in Brassica napus L. cv. Topas Specifically in Response to Ultraviolet B Radiation

We have shown in previous work that Brassica napus synthesizes epidermal flavonoids in response to UVB radiation (290–320 nm) and that these compounds are effective at screening the leaf mesophyll from UVB (Wilson and Greenberg, Photochem. Photobiol . 57, 556–563, 1993). This route of acclimation is common to many plant species. However, flavonoids are a highly diverse group of compounds that vary greatly from species to species, and little is known about the specific flavonoids synthesized in response to UVB. To address this, we extracted flavonoids from the leaves of B. napus plants exposed to photosynthetically active radiation (PAR: 400–700 nm), PAR + UVA (320–400 nm) and PAR + UVA + UVB. The compounds were resolved by HPLC and their structures were elucidated. Twelve distinct flavonoid glucosides with quercetin and kaempferol backbones were found. In some cases, a hydroxycinnamic acid moiety was linked via an ester bridge to a glucose. Of the 12 compounds identified, the leaf concentrations of 6 increased in response to UVB: kaempferol-3- O -sophoroside (K2), kaempferol-3- O -sophoroside-7- O -glucoside (Q3), quercetin-3- O -sophoroside (Q2), quercetin-3- O -sophoroside-7- O -glucoside (Q3), K3-coumaroyl ester and Q3-caffeoyl ester. Of these six compounds, K2, K3, Q2 and Q3 accumulated to high enough concentrations to contribute to UVB screening. Interestingly, the extractable amounts of the other six compounds identified were lower in the plants exposed to UVA or UVA + UVB compared to plants exposed only to PAR. Thus, in B. napus UV exposure seems to cause a shift in the population of flavonoid glycosides, with four of the UVB-induced flavonoids being generated in high concentrations.     

Effect of Ultraviolet Radiation Scattering by Deionized Water

Russian Journal of Physical Chemistry A - The effect of an increase in the intensity of light scattering from a deionized water sample in air over time in the UV region is revealed. The dependence...     

Differential Photosynthetic Response of a Green Tide Alga Ulva linza to Ultraviolet Radiation,Under Short‐ and Long‐term Ocean Acidification Regimes

Both ocean acidification (OA) and solar ultraviolet (UV) radiation can bring about changes in macroalgal physiological performance. However, macroalgal responses to UV radiation when acclimatized to OA under different time scales are rare. Here, we investigate the response of Ulva linza, a green tide alga, to UV radiation in the form of photosynthetically active radiation (PAR) or PAB (PAR+UVA+UVB) radiation. Radiation exposures were assessed following long‐term (from spore to adult stage, 1 month) and short‐term (adult stage, 1 week) OA treatments. Results showed that increased CO₂ decreased the damage rate (k) and repair rate (r) of thalli grown under short‐term OA conditions with PAB treatment, the ratio of r:k was not altered. Following long‐term OA conditions, r was not affected, although k was increased in thalli following PAB treatment, resulting in a reduced ratio of r:k. The relative level of UV inhibition increased and UV‐absorbing compounds decreased when algae were cultured under long‐term OA conditions. The recovery rate of thalli was enhanced when grown under long‐term OA after UV radiation treatment. These results show that blooming algae may be more sensitive to UV radiation in marine environments, but it can develop effective mechanisms to offset the negative effects, reflecting acclimation to long‐term OA conditions.     

Damaging Effects of Ultraviolet Radiation on the Cornea

The cornea sits at the anterior aspect of the eye and, like the skin, is highly exposed to ultraviolet radiation (UVR). The cornea blocks a significant proportion of UVB from reaching the posterior structures of the eye. However, UVA can penetrate the full thickness of the cornea, even reaching the anterior portion of the lens. Epidemiological data indicate that UVR is a contributing factor for a multitude of diseases of the cornea including pterygium, photokeratitis, climatic droplet keratopathy and ocular surface squamous neoplasia (OSSN), although the pathogenic mechanisms of each require further elucidation. UVR is a well‐known genotoxic agent, and its effects have been well characterized in organs such as the skin. However, we are only beginning to identify its effects on the cornea, such as the UVR signature C → T and CC → TT transversions identified by sequencing and increased proliferative and shedding rates in response to UVR exposure. Alarmingly, a single low‐dose exposure of UVR to the cornea is sufficient to elicit genetic, molecular and cellular changes, supporting the consideration of using protective measures, such as wearing sunglasses when outdoors. The aim of this review was to describe the adverse effects of UVR on the cornea.     

二乙基锌的同步辐射真空紫外光电离光解离

利用同步辐射光源和反射式飞行时间质谱, 在超声冷却条件下对二乙基锌(ZnC4H10)进行真空紫外(VUV, 能量范围为8-22 eV)光电离光解离研究. 实验获得ZnC4H10的光电离质谱图; 通过测量各碎片离子的光电离效率(PIE)曲线, 获得ZnC4H10的电离势(IP=8.20±0.05 eV)及其碎片离子(ZnC2H5+、ZnH+、Zn+、C2H5+、C2H3+等)的出现势. 根据实验结果, 并结合相关文献所给的热力学数据, 推导出这些主要碎片离子的生成焓, 并分析它们可能的解离通道和主要离子的分支比. 结果表明, 其主要解离通道是母体离子发生Zn—C 键的断裂形成ZnC2H5+和C2H5+离子, ZnC2H5+离子再进一步解离形成Zn+离子, 并且含锌碎片离子的丰度占75%以上.     

Photochemical Degradation of Aqueous Solutions of Organic Dyes under Exposure to Vacuum Ultraviolet Radiation

A xenon excimer silent-discharge lamp of original design intended for use in photochemical processes is described. The wavelength of excited xenon excimers is 172 nm with a full width at half maximum of 16 nm. The operating efficiency of the lamp was demonstrated using the decolorization of aqueous solutions of the azo dye Acid Yellow 99 as an example. The photodegradation kinetics of the dye obeys an exponential law, as determined by measuring color decay at _max1 = 22000 cm^–1, and depends on the interaction of dye molecules with OH^· radicals.     

A Model for Inactivation of Microbes Suspended in the Atmosphere by Solar Ultraviolet Radiation

Solar ultraviolet (UV) light within 280–320 nm (UVB) is the primary cause for virus inactivation in the atmosphere. Only the effect of the direct component has been previously evaluated. We developed a simple regression model to estimate the inactivation of a virus due to direct (unscattered), diffuse (scattered) and total (direct + diffuse) components of solar UV (daily integrated irradiances). The model predicts the maximum number of radiation-days a virus will survive at a given altitude above the ground in rural and urban environments under clear skies. We explored the effect of several environmental variables: visibility, altitude and ground reflectivity. We found that the effect of diffuse radiation on virus inactivation was larger than the direct component. The diffuse irradiance increased with ground albedo (mainly due to reflection of the direct attenuated solar off the ground) and decreased with increased visibility (proportional to aerosol loading in the atmosphere). The diffuse component increased with altitude, but the ratio of diffuse to the total decreased with increased altitude, highlighting the importance of the diffuse component of UV near the ground. Our model may help public health studies in predicting and understanding the effect of environmental parameters on the survival of germs.     

纳米ZnO对白僵菌孢子的紫外保护及与孢子的生物相容性

用沉淀法制备经油酸表面修饰的纳米ZnO,测定其紫外吸收性能及对油悬浮剂型白僵菌孢子的抗紫外保护效率;用扫描电子显微镜观察纳米ZnO与孢子的混合状态,通过对含纳米ZnO的白僵菌制剂在贮存期间孢子萌发率差异显著性的分析,确定其与白僵菌孢子的生物相容性.结果表明：制备的纳米ZnO的平均粒径为27nm,其对波长200nm～370nm范围的紫外光具有良好的吸收性能.含纳米ZnO质量分数为1.0%、2.0%和5.0%的油悬浮剂型白僵菌,紫外灯照射8h,对孢子保护效率均大于60%,不含纳米ZnO为9.7％. 纳米ZnO被吸附包覆于孢子表面,屏蔽紫外线,保护孢子免受紫外线的杀伤.含0.5%、1.0%和2.0%纳米ZnO的油悬浮剂型白僵菌制剂室温贮存10个月,其孢子萌发率与不含纳米ZnO的差异不显著;纳米ZnO与白僵菌孢子生物相容性好.油悬浮剂型白僵菌制剂中纳米ZnO的适宜含量为1.0%～2.0%.