A new model to accurately measure the radon exhalation rate from soil using AlphaGUARD.

Radon exhalation rate from soil is a critical factor in evaluating environmental radon levels. However, AlphaGUARD PQ2000PRO may have some sensitivity towards thoron, which can have a significant impact on radon measurement. The traditional radon exhalation models generally ignore the presence of thoron, leading to an overestimation of the radon exhalation rate from soil. To handle this issue, a new model was proposed based on an analysis of several previous studies on radon exhalation theories. To prove the feasibility of the model, the radon exhalation rate measurements were performed by two different types of detectors-AlphaGUARD PQ2000PRO and RAD7. The radon exhalation rate obtained by using the new model is in good agreement with that obtained by using the theoretical model of radon exhalation of RAD7 within one standard error. This new model can be applied to accurately measure radon exhalation rate from soil by the PIC detector (PQ2000PRO).

Design of intermittent continuous measurement of radon concentration in water.

The U.S. Environmental Protection Agency established the maximum contaminant level limit for radon concentration in drinking water as 11.1 Bq L-1. A new device based on the bubbling method with a 290 mL sample bottle was designed for intermittent continuous measurement of water radon concentration. A STM32 is used to control the switch of the water pump and the valves. The Water-Radon-Measurement software written in C# is to connect RAD7 and calculate the water radon concentration automatically.

COMPARISON OF RADON EXHALATION RATE MEASUREMENTS ON REFERENCE DEVICE IN OPEN AND CLOSED LOOP BY ALPHAGUARD IN FLOW-THROUGH MODE.

Radon-222 (Rn-222) exhalation rate is vital for estimating radiation risk from many kinds of materials. AlphaGUARD measures the radon concentration based on the ionization chamber principle, which is currently recognized as a reference instrument to measure radon. In China, measurements of radon exhalation rate are performed by AlphaGUARD operated in flow-through mode on a reference device to verify measurement accuracy. These measurements are performed in both open and closed loop. AlphaGUARD can fast rapidly the variation of the radon concentration in the chamber, which is tightly pressed against the surface of the medium to accumulate the exhaled radon. When the model is used to obtain the radon exhalation rate, the radon exhalation rates obtained by nonlinear data fitting on the measured radon concentrations are similar to the reference value of the device. The difference of radon exhalation rate values of six measurements is small.

OPTIMIZING THE INTERNAL CELL STRUCTURE OF THE RADON MONITOR BASED ON ELECTROSTATIC COLLECTION METHOD.

As Rn-222 decays, an alpha particle is emitted and the residual polonium nucleus recoils in the opposite direction. At the end of the recoil path, 88% of the polonium atoms have a positive charge and 12% are neutral. The electric potential distribution in the 60 ml hemispherical internal cell of the radon monitor based on electrostatic collection is studied for reducing the combined probability of the positively charged Po-218 and the OH- produced by the ionization of water vapour in the air. The COMSOL software is used to simulate the electric potential distribution in the internal cell of the radon monitor based on the electrostatic collection method at 27°C, a pressure of 0.1 Mpa. For improving the collection efficiency of Po-218 ions, the average collection time along vertical and oblique lines is calculated when the upper surface of the internal cell is plastic, uncharged metal and charged metal, respectively. Assuming that the gas in the internal cell is uniformly distributed, the results show that if the upper surface of the hemispherical internal cell is plastic or uncharged metal, the electric potential formed in the internal cell is more uniform, and it is beneficial to reduce the total collection time of the positively charged Po-218 ions, thereby improving collection efficiency. The simulation results can be used as an effective reference for optimizing the design of the internal cell structure of the radon monitor based on electrostatic collection method.

A model comparison of diffusion-controlled radon exhalation from solid and cavity walls with application to high background radiation areas.

Radon exhaled from building material surfaces is an important source of indoor radon. Yangjiang, located in the southern part of mainland China, is well-known as a high background radiation area (HBRA). Rather, high levels of radon and thoron concentration have been observed in adobe and brick houses. Reducing the indoor radon concentration remains an important issue in the high background radiation areas of China and the world. Generally, the walls of Chinese dwellings are solid. In this paper, a simple one-dimensional model for predicting the radon diffusion in a cavity wall is proposed, and an analysis formula describing the radon exhalation rate from cavity wall surfaces is presented. The influence on the radon exhalation rate due to leakage through structural joints and building material cracks is analyzed. The simulation results indicate that the radon exhalation rate from a cavity wall surface is far lower than that from a solid wall. The structure of cavity walls themselves is therefore useful as a mechanism for reducing the indoor radon in high background radiation areas across the world.

No flow meter method for measuring radon exhalation from the medium surface with a ventilation chamber.

The method for measuring radon exhalation rate from the medium surface with a ventilation chamber is un-replaceable when surveying the radon exhalation rate continuously. Generally, the pump flow rate is an important parameter to obtain the radon exhalation rate from the measurement model. Our previous research indicated that the results of those measurements are inaccurate when the air change rate is not far larger than the effective decay constant. A no flow meter method is proposed for measuring radon exhalation from the medium surface with a ventilation chamber. A constant K is used to replace the sum of the air change rate and the effective decay constant. The radon exhalation rate and the value of K can be obtained by nonlinear data fitting through a novel model. The air flow rate is not a parameter of this model, and the flow meter is unnecessary in this measurement. The radon exhalation rates obtained by verification experiments are within the accepted values for the reference value. This method can be applied to develop and improve the instruments for measuring radon exhalation rate.

A method to simultaneously and continuously measure the 222Rn and 220Rn exhalation rates of soil in an open loop.

This paper presents a process in which a radon monitor based on the electrostatic collection method is used to measure the (222)Rn and (220)Rn exhalation rates simultaneously and continuously employing a ventilation-type accumulation chamber. Generally, the radon exhalation rate can be measured by accumulation technique, but cannot be measured continuously. The advantage of this method using a ventilation-type accumulation chamber is that the radon exhalation rates can be measured continuously. Even though the environmental air is drawn into the chamber, the low atmospheric values of radon and thoron do not influence the measurement accuracy. The (222)Rn and (220)Rn exhalation rates error from the environmental air is less than 5% in this experiment.

Spherical headed silicone intubation in the treatment of 26 cases (31 eyes) of chronic dacryocystitis under nasal endoscopy.

PURPOSE: To observe the clinical efficacy of spherical headed silicone implantation in the treatment of chronic dacryocystitis under nasal endoscopy. METHODS: Twenty six patients (31 eyes) with chronic dacryocystitis were subjected to spherical headed silicone implantation under topical anesthesia (lacrimal passage and nasal mucosal surface). Lacrimal passage irrigation was performed daily throughout the first postoperative week , and once each month thereafter. RESULTS: All spherical headed silicone tube placements were successfully performed. The operative time ranged from 6 to 11 minutes. Symptoms of epiphora were immediately ameliorated post-operatively, and irrigation demonstrated patency of the lacrimal system in all patients. All patients were followed from 7 to 24 months, during which symptoms of tearing were improved. The lacrimal ducts of 27 eyes (87.7%) were normal. The lacrimal ducts of 4 others (12.3%) were still blocked. Lacrimal passage irrigation was open and secretion disappeared in 28 eyes (90.3%). Tearing was observed in 3 eyes (9.68%). CONCLUSION: Spherical headed silicone tube implantation under nasal endoscopy is successful in relieving symptoms of tearing.

Association of CYP2D6 single-nucleotide polymorphism with response to ophthalmic timolol in primary open-angle Glaucoma--a pilot study.

OBJECTIVES: We aimed to investigate whether CYP2D6 polymorphisms were associated with the intraocular pressure (IOP)-lowering effect and systemic complications (especially bradycardia) of ophthalmic timolol. METHODS: One hundred twenty-three primary open-angle glaucoma subjects (123 eyes) were treated with 0.5% aqueous formulations of ophthalmic timolol. IOP and heart rate were measured before and after timolol administration. DNA was extracted from venous leukocytes of all the subjects. Two single-nucleotide polymorphisms (SNPs) of CYP2D6, for example, rs16947 (2850C>T, R296C) and rs1135840 (4180C>G, S486T), were detected by restriction fragment length polymorphism analysis. RESULTS: Neither rs16947 (P = 0.339) nor rs1135840 (P = 0.903) genotype was statistically correlated with the IOP-lowering effect of timolol eye drops. The rs16947 genotype was significantly associated with occurrence of bradycardia in primary open-angle glaucoma patients (P = 0.021). The patients with rs16947 CT (P = 0.043) or TT (P = 0.043) were more inclined to bradycardia than those with rs16947 CC, although there was no significant difference between CT and TT (P = 0.177). The analysis of variance showed no significant difference in heart rate (P = 0.559) among GG, GC, and CC groups. CONCLUSIONS: CYP2D6 SNP rs16947 may confer susceptibility to timolol-induced bradycardia. Patients with CC genotype were unlikely to suffer from timolol-induced bradycardia, whereas those with TT genotype were found to suffer from timolol-induced bradycardia.

Cytochrome oxidase 2D6 gene polymorphism in primary open-angle glaucoma with various effects to ophthalmic timolol.

AIMS: Timolol is used topically for the treatment of glaucoma and metabolized by cytochrome P450 (CYP) 2D6 in the liver. The aim of this study is to test the hypothesis that CYP 2D6 single-nucleotide polymorphism (SNP) is associated with drug effects of ophthalmic timolol. METHODS: A total of 133 primary open-angle glaucoma (POAG) subjects underwent the ophthalmic single timolol administration and the drug effects were observed, including lowering the effects of intraocular pressure (IOP) and side effects (i.e., appearing bradycardia). Eight SNPs of CYP2D6 were investigated in 73 subjects by a SNPstream genotyping system. The relationship between the effects of timolol and CYP2D6 Arg296Cys and Ser486Thr genotype distribution in these POAG subjects was analyzed. RESULTS: Topical timolol administration had significant effect on IOP (P = 0.000) and heart rate (HR) (P = 0.000) in all 133 subjects, and individual ocular hypotensive effect of timolol varied between 0 and 23 mmHg. Individual effect of HR varied between -31 and 10 beats per minute, in the present study. According to SNP genotyping in 73 subjects, there was no significant difference of IOP between subjects with different CYP2D6 Arg296Cys (P = 0.308) or Ser486Thr genotypes (P = 0.741). The effect of timolol on HR was significantly different between subjects with different Arg296Cys genotypes (P = 0.046). Timolol-induced bradycardia tended to occur in subjects with Arg296Cys CT and TT genotype when compared with CC genotype (P = 0.009). CONCLUSIONS: CYP2D6 SNP Arg296Cys appeared to be correlative with the intersubject variability seen with timolol in POAG subjects. Subjects with CC genotype trended to avoid timolol-induced bradycardia, and subjects with TT genotype trended to have poorer timolol-induced ocular hypotensive effects.

Effects of pirfenidone on proliferation, migration, and collagen contraction of human Tenon's fibroblasts in vitro.

PURPOSE: To investigate the effect of pirfenidone, a novel antifibrotic agent, on proliferation, migration, and collagen contraction of human Tenon's fibroblasts (HTFs). METHODS: After treatment of HTFs with pirfenidone, cell proliferation was measured by MTT assay. Cell migration was investigated by scratch assay. Contractility was evaluated in fibroblast-populated collagen gels. Cell viability was determined by trypan blue exclusion assay. The expression of TGF-beta1, -beta2, and -beta3 was estimated with RT-PCR, Western blot, and immunofluorescence analyses. RESULTS: Pirfenidone induced significant dose-dependent inhibition of HTF proliferation and migration and collagen contraction. After treatment with different concentrations of pirfenidone (0.15, 0.3, and 1 mg/mL) for 24 and 72 hours, cell viability was not different in the treatment and control groups. After 24 hours of treatment with pirfenidone, HTFs showed dose-dependent decreases in mRNA and protein levels of TGF-beta1, -beta2, and -beta3. CONCLUSIONS: These findings indicate that pirfenidone inhibits proliferation, migration, and collagen contraction of HTFs at nontoxic concentrations. A decrease in autocrine TGF-beta signaling may have a role in the effects of pirfenidone.