Energy-Transfer Processes of Xe（6p[1/2]0,6p[3/2]2,and 6p[5/2]2） Atoms under the Condition of Ultrahigh Pumped Power

The kinetic processes of Xe(6p[1/2]0, 6p[3/2]2, and 6p[5/2]2) atoms under the focused condition were investigated. The atomic density of the laser prepared state significantly increases. Therefore, the probability of the energy-pooling between two high-lying atoms increases. There are three major types of the energy-pooling collisions. The first type is the energy-pooling ionization. Once the excitation laser is focused, the obvious ionization can be observed from the side window whenever the laser prepared state is 6p[1/2]0, 6p[3/2]2, or 6p[5/2]2 state. Ionization of Xe is attributed to the energy-pooling ionization or a Xe* atom reabsorbing another excitation photon. The second type is energy-pooling with big energy difference. When the 6p[1/2]0 state is the laser prepared state, the energy-pooling collision between two 6p[1/2]0 atoms can produce one 5d[3/2]1 atom and one 6s'[1/2]0 atom. The third type is energy-pooling with small energy difference. The intensities of fluorescence lines are much stronger that five secondary 6p states act as the upper states, and the rising edges of these fluorescence lines are much steeper. The primary mechanism of generating the secondary 6p atoms is energy-pooling collision instead of collision relaxation. Based on the collision probability, the rate of energy-pooling between two 6p[1/2]0 atoms is deduced (6.39x10^8s-1). In addition, the 6s atoms also increase under the focused condition. Therefore, all the fluorescence lines are serious trailing by radiation trapping.

Bilateral retrocorneal hyaline scrolls secondary to asymptomatic congenital syphilis: A case report

BACKGROUND Retrocorneal hyaline scrolls are a rare phenomenon.We report a case of bilateral retrocorneal hyaline scrolls that were likely induced by asymptomatic congenital syphilis.CASE SUMMARY A 71-year-old woman presented with blurred vision due to cataracts.Slit-lamp microscopy revealed bilateral hyaline scrolls with a dichotomous branching pattern extending to the anterior chamber or rods attaching to the rough posterior surface of the cornea.The patient was positive for syphilis-specific antibodies,with no ocular or systemic evidence of congenital or acquired syphilis.Binocular cataract,retrocorneal scroll,and corneal endothelial gutta were considered.The scroll of the right eye was removed during cataract surgery and further observed using hematoxylin–eosin staining and scanning electron microscopy.The cornea of the right eye remained transparent,and the residual scroll seemed stable,however,the corneal endothelial density declined at 13 mo after surgery.In vivo confocal microscopy revealed coalescence of corneal guttae at the level of the corneal endothelium or adhesion to the posterior surface of the endothelium,with enlarged endothelial cells in both eyes.Activated keratocytes in the stroma and a highly reflective acellular structure at the level of the Descemet’s membrane were observed.The removed scroll had a cartilage-like hardness and a circularly arranged fiber-like acellular structure.CONCLUSION Occult congenital syphilis could induce corneal endothelial gutta and theformation of retrocorneal scrolls without other signs of ocular syphilis.

Kinetics of the Simplest Criegee Intermediate CH2OO Reacting with CF3CF=CF2

CF3CF=CF2 is a potential source of atmospheric trifluoroacetic acid(CF3C(O)OH).The kinetics of the reaction of the simplest Criegee intermediate(CH2OO)with CF3CF=CF2 was studied by using the OH laser-induced fluorescence method.At 10 torr,the rate co-efficients were measured to be(1.45±0.14)×10^-13,(1.18±0.11)×10^-13,(1.11±0.08)×10^-13,and(1.04±0.08)×10^-13·cm^3·molecule^-1·s^-1 at 283,298,308 and 318 K,respectively.The activation energy of(-1.66±0.21)kcal/mol was derived from the Arrhenius equation.No obvious pressure dependence was observed.

Dispersion modeling and health risk assessment of dioxin emissions from a municipal solid waste incinerator in Hangzhou,China

The emission of dioxins from municipal solid waste incinerators(MSWIs) has become a widespread concern.The effect of meteorological parameters(wind speed,atmospheric stability and mixing height) on the hourly ground level concentration(GLC) of dioxins was estimated using air dispersion models.Moreover,the health risks of dioxin exposure were evaluated for children and adults using the Nouwen equation.The total environmental exposure via air inhalation and food ingestion was calculated,based on linear fit equations.The results indicate that potentially severe pollution from dioxins occurs at a wind speed of 1.5 m/s with atmospheric stability class F.In addition,local residents in the study area are exposed to severe weather conditions most of the time,and the risk exposures for children are far higher than those for adults.The total exposure for children far exceeds the tolerable daily intake of dioxin recommended by the World Health Organization(WHO) of 1-4 pg TEQ/(kg·d) under severe weather conditions.Results from modeling calculations of health risk assessment were consistent with dioxin levels obtained during actual monitoring of emissions.