Diurnal Variations in Solar Ultraviolet Radiation at Typical Anatomical Sites

Objective Solar ultraviolet （UV） radiation is an important environmental factor that affects human health. The understanding of diurnal variations of UV radiation at anatomical sites may be helpful in developing ways to protect humans from the harmful effects of UV radiation. Methods In order to characterize the diurnal variations, the UV exposure values were measured at 30 min intervals by using Solar-UV Sensors and a rotating manikin in Shenyang city of China （41°51＇N, 123°27%）. Measurement data for four representative days （in each of the four seasons respectively） were analyzed. Results The diurnal variations in solar UV radiation at the shoulder, the forehead and the chest were similar to those associated with a horizontal control measurement. However, the diurnal variations at the eye and the cheek exhibited bimodal distributions with two peaks in spring, summer and autumn, and a unimodal distribution in winter. The UV exposure peaks at the eye and the cheek were measured at solar elevation angles （SEA） of about 30° and 40°, respectively. Conclusion The protection of some anatomical sites such as the eye from high UV exposure should not be focused solely on the periods before and after noon, especially in the places and seasons with high SEA.

High-value utilization of CO_(2) to synthesize sulfur-doped carbon nanofibers with excellent capacitive performance

Carbon nanofiber(CNF)is considered a promising material due to its excellent physical and chemical properties.This paper proposes a novel way to transform CO_(2) into heteroatom-doped CNFs,with the introduction of Fe,Co,and Ni as catalysts.When the electrolyte containing Ni O,Co2O3,and Fe_(2)O_(3) was employed,sulfur-doped CNFs in various diameters were obtained.With the introduction of Fe catalyst,the obtained sulfur-doped CNFs showed the smallest and tightest diameter distributions.The obtained sulfur-doped CNFs had high gravimetric capacitance(achieved by SDG-Fe)that could reach 348.5 F/g at 0.5 A/g,excellent cycling stability,and good rate performance.For comparison purposes,both Fe and nickel cathodes were tested,where the active metal atom at their surface could act as catalyst.In these two situations,sulfur-doped graphite sheet and sulfur-doped graphite quasi-sphere were the main products.

Prevalence and risk factors of lens opacities in rural populations living at two different altitudes in China

AIM： To investigate the prevalence of and risk factors for lens opacities in populations living at two different altitudes in China.·METHODS： A total of 813 subjects aged ≥40y in Lhasa（Tibet Autonomous Region, China. Altitude： 3658 m） and Shaoxing（Zhejiang Province, China. Altitude： 15 m） were underwent eye examinations and interviewed in this cross-sectional study. Participants＇ lens opacities were graded according to the Lens Opacities Classification System II（LOCS II） and the types of opacities with LOCS II scores ≥2 were determined. Univariate and stepwise logistic regression were used to evaluate the associations of independent risk factors with lens opacities.· RESULTS： Lens opacities were significantly more prevalent in the high-altitude than in the low-altitude area（χ2=10.54, P 〈0.001）. Lens opacities appear to develop earlier in people living at high than at low altitude. The main types of lens opacity in Lhasa and Shaoxing were mixed（23.81%） and cortical（17.87%）,respectively. Independent risk factors associated with all lens opacities were age, ultraviolet（UV） radiation exposure,and educational level. Compared with participants aged40-49 y, the risk of lens opacities increased gradually from 2 to 85 times per 10 y [odds ratio（OR）=2.168-84.731,P 〈0.05）. The risk of lens opacities was about two times greater in participants with the highest UV exposure than in those with the lowest exposure（OR=2.606, P =0.001）.Educational level was inversely associated with lensopacities; literacy deceased the risk by about 25%compared with illiteracy（OR=0.758, P =0.041）.·CONCLUSION： Old age, higher UV exposure and lower educational level are important risk factors for the development of lens opacities. Lens opacities are more prevalent among high-altitude than low-altitude inhabitants.

Green-emitting Polyfluorenes Containing Hexylthiophen-dibenzothiophene-S,S-dioxide Unit with Large Two-photon Absorption Cross Section

Green light-emitting polyfluorenes containing 3,7-bis（4-hexylthiophen-2-yl）dibenzo[b,d]thiophene 5,5-dioxide（DHTSO）unit were synthesized.All the resulted polymers show high thermal stability with the decomposition temperatures（T_d）over 420°C and the glass transition temperatures（T_g）over 75°C.The polymers exhibit the enhanced highest occupied molecular orbital（HOMO）energy levels and the depressed lowest unoccupied molecular orbital（LUMO）energy levels with the increase of DHTSO unit in polymers.The photoluminescence（PL）spectra of the polymers show positive solvatochromism in solution with the variation of solution polarities,indicating remarkable intramolecular charge transfer（ICT）effect in the polymers containing DHTSO moiety.The fluorescence quantum yields（（37）_（PL））are in the range of 34%-67%for PF-DHTSOs in film.All polymers possess two photon absorption（TPA）properties,and the TPA cross sections（？_2）are enhanced with increasing DHTSO unit in polymers.The highest？_2 is 2392 GM for PF-DHTSO15 in chloroform solution upon 740 nm excitation.The device of PF-DHTSO15 shows green emission with the Commission Internationale de L’.Eclairage（CIE）coordinates of（0.26,0.59）,and the maximum luminous efficiency（LE_（max））of 10.8 cd·A^（-1） with the configuration of ITO/PEDOT：PSS/EL/Cs F/Al.These results indicate that introducing DHTSO unit into polyfluorene backbone could be a promising molecular design strategy for TPA and effective green-light emission.