Public exposure to radon has attracted increasing public concern. The newly issued "Standards for indoor air quality (GB/T 18883-2022)" has revised the radiological parameters of radon. This study analyzed and discussed the relevant technical contents about the derivation of radon limit, including the distribution level for indoor radon, exposure pathway, health effects, and the process for establishing the standard limits. Specific implementation and evaluation suggestions are also proposed.
Humans ; Radon/analysis* ; Air Pollution, Indoor ; China ; Housing

Public exposure to radon has attracted increasing public concern. The newly issued "Standards for indoor air quality (GB/T 18883-2022)" has revised the radiological parameters of radon. This study analyzed and discussed the relevant technical contents about the derivation of radon limit, including the distribution level for indoor radon, exposure pathway, health effects, and the process for establishing the standard limits. Specific implementation and evaluation suggestions are also proposed.
Humans ; Radon/analysis* ; Air Pollution, Indoor ; China ; Housing

OBJECTIVE: The purpose of this study was to determine whether xenon post-conditioning affects mTOR signaling as well as endoplasmic reticulum stress (ERS)-apoptosis pathway in rats with spinal cord ischemia/reperfusion injury. METHODS: Fifty male rats were randomized equally into sham-operated group (Sham group), I/R model group (I/R group), I/R model+ xenon post-conditioning group (Xe group), I/R model+rapamycin (a mTOR signaling pathway inhibitor) treatment group (I/R+ Rapa group), and I/R model + xenon post- conditioning with rapamycin treatment group (Xe + Rapa group).. In the latter 4 groups, SCIRI was induced by clamping the abdominal aorta for 85 min followed by reperfusion for 4 h. Rapamycin (or vehicle) was administered by daily intraperitoneal injection (4 mg/kg) for 3 days before SCIRI, and xenon post-conditioning by inhalation of 1∶1 mixture of xenon and oxygen for 1 h at 1 h after initiation of reperfusion; the rats without xenon post-conditioning were given inhalation of nitrogen and oxygen (1∶ 1). After the reperfusion, motor function and histopathologic changes in the rats were examined. Western blotting and real-time PCR were used to detect the protein and mRNA expressions of GRP78, ATF6, IRE1α, PERK, mTOR, p-mTOR, Bax, Bcl-2 and caspase-3 in the spinal cord. RESULTS: The rats showed significantly lowered hind limb motor function following SCIRI (P < 0.01) with a decreased count of normal neurons, increased mRNA and protein expressions of GRP78, ATF6, IRE1α, PERK, and caspase-3, and elevated p-mTOR/mTOR ratio and Bax/Bcl-2 ratio (P < 0.01). Xenon post-conditioning significantly decreased the mRNA and protein levels of GRP78, ATF6, IRE1α, PERK and caspase-3 (P < 0.05 or 0.01) and reduced p-mTOR/mTOR and Bax/Bcl-2 ratios (P < 0.01) in rats with SCIRI; the mRNA contents and protein levels of GRP78 and ATF6 were significantly decreased in I/R+Rapa group (P < 0.01). Compared with those in Xe group, the rats in I/R+Rapa group and Xe+Rapa had significantly lowered BBB and Tarlov scores of the hind legs (P < 0.01), and caspase-3 protein level and Bax/Bcl-2 ratio were significantly lowered in Xe+Rapa group (P < 0.05 or 0.01). CONCLUSION By inhibiting ERS and neuronal apoptosis, xenon post- conditioning may have protective effects against SCIRI in rats. The mTOR signaling pathway is partially involved in this process.
Animals ; Apoptosis ; Caspase 3/metabolism* ; Endoplasmic Reticulum Stress ; Endoribonucleases/pharmacology* ; Injections, Intraperitoneal ; Male ; Neurons/pathology* ; Nitrogen/metabolism* ; Oxygen/metabolism* ; Protein Serine-Threonine Kinases ; Proto-Oncogene Proteins c-bcl-2/metabolism* ; RNA, Messenger/metabolism* ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury/metabolism* ; Sirolimus/pharmacology* ; Spinal Cord Ischemia/pathology* ; TOR Serine-Threonine Kinases/metabolism* ; Xenon/therapeutic use* ; bcl-2-Associated X Protein/metabolism*

Objective: To explore the occupational hazards caused by three kinds of welding operations, and to provide data support for individual protection. Methods: In October 2020, the welding fumes, metal elements and welding arc generated by three welding operations of argon gas shielded welding (JS80 welding wire) , manual welding (ZS60A welding rod) and carbon dioxide shielded welding (907A flux cored wire) were collected and measured in the welding laboratory. The samples were analyze and compare in the laboratory, and the differences of the occupational hazard factors of the three welding operations were judged. Results: The concentration of welding fume produced by carbon dioxide shielded welding, manual welding (ZS60A electrode) , and argon gas shielded welding (JS80 welding wires) were 6.80 mg/m(3), 6.17 mg/m(3), and 3.13 mg/m(3), respectively. The effective irradiance of the welding arc outside the welding mask from high to low is manual welding (ZS60A electrode) , carbon dioxide shielded welding (907A flux-cored welding wire) , and argon shielded welding (JS80 welding wire) , respectively 1 010.7, 740.9, 589.5 μW/cm(2). The long-wave ultraviolet UVA intensity generated by argon shielded welding (JS80 welding wire) is the largest, which is 1 500 μW/cm(2). The content of Mn in the three welding operations is the highest, and JS80 welding wire has the highest Mn content of 128493.2 mg/kg. 907A flux cored wire has the highest Ti content, which is 24355.5mg/kg. The electrode ZS60A has the highest Cu content, which is 24422.12 mg/kg. Conclusion: The intensity of occupational hazards is different in the three kinds of welding operations, so the methods of personal protective equipment, field exposure assessment and health monitoring should be more targeted.
Air Pollutants, Occupational/analysis* ; Argon/analysis* ; Carbon Dioxide/analysis* ; Gases/analysis* ; Occupational Exposure/analysis* ; Welding/methods*

Quench of magnetic resonance imaging system refers to the process that the superconducting condition inside the magnet is destroyed due to some reason. The large current stored in the coil is quickly converted into heat at the place where the resistance is formed, and a large amount of liquid helium in the magnet is evaporated. If it happens, it will cause huge loss to the user. We introduce the real cases of 1.5 T magnetic resonance imaging system's quench fault, maintenance treatment and management improvement, which can be used for reference by various medical institutions, so as to better strengthen the operation and maintenance management of magnetic resonance imaging system, so as to avoid the occurrence of out of tolerance fault, and do a good job in the guarantee work after the out of tolerance fault.
Helium ; Magnetic Resonance Imaging ; Magnets

Radon is a naturally occurring radioactive material that is formed as the decay product of uranium and thorium, and is estimated to contribute to approximately half of the average annual natural background radiation. When inhaled, it damages the lungs during radioactive decay and affects the human body. Through many epidemiological studies regarding occupational exposure among miners and residential exposure among the general population, radon has been scientifically proven to cause lung cancer, and radon exposure is the second most common cause of lung cancer after cigarette smoking. However, it is unclear whether radon exposure causes diseases other than lung cancer. Media reports have often dealt with radon exposure in relation to health problems, although public attention has been limited to a one-off period. However, recently in Korea, social interest and concern about radon exposure and its health effects have increased greatly due to mass media reports of high concentrations of radon being released from various close-to-life products, such as mattresses and beauty masks. Accordingly, this review article is intended to provide comprehensive scientific information regarding the health effects of radon exposure.
Background Radiation ; Beauty ; Beds ; Epidemiologic Studies ; Human Body ; Inhalation Exposure ; Korea ; Lung ; Lung Neoplasms ; Masks ; Mass Media ; Miners ; Occupational Exposure ; Radon ; Smoking ; Thorium ; Uranium

Since the Compton camera was fi rst introduced, various types of conical Radon transforms have been examined. Here, we derive the inversion formula for the conical Radon transform, where the cone of integration moves along a curve in three-dimensional space such as a helix. Along this three-dimensional curve, a detailed inversion formula for helical movement will be treated for Compton imaging in this paper. The inversion formula includes Hilbert transform and Radon transform. For the inversion of Compton imaging with helical movement, it is necessary to invert Hilbert transform with respect to the inner product between the vertex and the central axis of the cone of the Compton camera. However, the inner product function is not monotone. Thus, we should replace the Hilbert transform by the Riemann–Stieltjes integral over a certain monotone function related with the inner product function. We represent the Riemann–Stieltjes integral as a conventional Riemann integral over a countable union of disjoint intervals, whose end points can be computed using the Newton method. For the inversion of Radon transform, three dimensional fi ltered backprojection is used. For the numerical implementation, we analytically compute the Hilbert transform and Radon transform of the characteristic function of fi nite balls. Numerical test is given, when the density function is given by a characteristic function of a ball or three overlapping balls.
Methods ; Radon

PURPOSE: Direct application of atmospheric-pressure plasma jets (APPJs) has been established as an effective method of microbial decontamination. This study aimed to investigate the bactericidal effect of direct application of an APPJ using helium gas (He-APPJ) on Porphyromonas gingivalis biofilms on sandblasted and acid-etched (SLA) titanium discs. METHODS: On the SLA discs covered by P. gingivalis biofilms, an APPJ with helium (He) as a discharge gas was applied at 3 different time intervals (0, 3, and 5 minutes). To evaluate the effect of the plasma itself, the He gas–only group was used as the control group. The bactericidal effect of the He-APPJ was determined by the number of colony-forming units. Bacterial viability was observed by confocal laser scanning microscopy (CLSM), and bacterial morphology was examined by scanning electron microscopy (SEM). RESULTS: As the plasma treatment time increased, the amount of P. gingivalis decreased, and the difference was statistically significant. In the SEM images, compared to the control group, the bacterial biofilm structure on SLA discs treated by the He-APPJ for more than 3 minutes was destroyed. In addition, the CLSM images showed consistent results. Even in sites distant from the area of direct He-APPJ exposure, decontamination effects were observed in both SEM and CLSM images. CONCLUSIONS: He-APPJ application was effective in removing P. gingivalis biofilm on SLA titanium discs in an in vitro experiment.
Bacterial Load ; Biofilms ; Decontamination ; Helium ; In Vitro Techniques ; Methods ; Microbial Viability ; Microscopy, Confocal ; Microscopy, Electron, Scanning ; Plasma Gases ; Plasma ; Porphyromonas gingivalis ; Porphyromonas ; Stem Cells ; Titanium

PURPOSE: We report two cases of intraocular lens (IOL) pupillary optic capture following IOL scleral fixation treated with argon laser iridotomy. CASE SUMMARY: (Case 1) A 69-year-old man presented with suddenly decreased visual acuity of the left eye. The best-corrected visual acuity was finger count (FC) 30 cm in the left eye. Slit lamp examination revealed subluxation of the left eye IOL. An IOL scleral fixation and anterior vitrectomy were performed and no specific findings were observed. During the follow-up period, pupillary optic capture was repeated without specific causes, such as trauma, or IOL decentration thus, argon laser iridotomy was performed. (Case 2) A 77-year-old man presented with a 3-day history of congestion of the left eye and decreased visual acuity. Best-corrected visual acuity was 0.4 logarithm of the minimum angle of resolution (logMAR) in the left eye. Slit lamp examination revealed subluxation of the left eye IOL. An IOL scleral fixation and anterior vitrectomy were performed, and no specific findings were observed. During the follow-up period, pupillary optic capture was found, and IOL repositioning and argon laser iridotomy were performed. CONCLUSIONS: Laser iridotomy can be used to prevent recurrence of pupillary optic capture in eyes with IOL scleral fixation without decentration or distortion.
Aged ; Argon ; Estrogens, Conjugated (USP) ; Fingers ; Follow-Up Studies ; Humans ; Lenses, Intraocular ; Recurrence ; Slit Lamp ; Visual Acuity ; Vitrectomy

Radon is a naturally occurring radioactive material formed by the slow decay of uranium and thorium found in the earth's crust or construction materials. Internal exposure to radon accounts for about half of the natural background radiation dose to which humans are exposed annually. Radon is a carcinogen and is the second leading cause of lung cancer following smoking. An association between radon and lung cancer has been consistently reported in epidemiological studies on mine workers and the general population with indoor radon exposure. However, associations have not been clearly established between radon and other diseases, such as leukemia and thyroid cancer. Radiation doses are assessed by applying specific dose conversion coefficients according to the source (e.g., radon or thoron) and form of exposure (e.g., internal or external). However, regardless of the source or form of exposure, the effects of a given estimated dose on human health are identical, assuming that individuals have the same sensitivity to radiation. Recently, radiation exceeding the annual dose limit of the general population (1 mSv/yr) was detected in bed mattresses produced by D company due to the use of a monazite-based anion powder containing uranium and thorium. This has sparked concerns about the health hazards for mattress users caused by radiation exposure. In light of this event, this study presents scientific information about the assessment of radon and thoron exposure and its human implications for human health, which have emerged as a recent topic of interest and debate in society.
Background Radiation ; Beds ; Carcinogens ; Construction Materials ; Epidemiologic Studies ; Humans ; Korea ; Leukemia ; Lung Neoplasms ; Miners ; Radiation Exposure ; Radon ; Smoke ; Smoking ; Thorium ; Thyroid Neoplasms ; Uranium