Publications by authors named "Kai Chung Cheng"

Secondhand exposure to cannabis smoke occurs in public outdoor locations due to outdoor smoking or leakage of indoor smoking. Very little is known regarding the actual levels of exposure. This study examined PM2.

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The widespread legalization of recreational marijuana raises growing concerns about exposure to secondhand marijuana smoke. An important location for marijuana smoking is the home, but few measurements of air pollutant concentrations in the home are available for a marijuana joint fully smoked in one of its rooms. We used research grade calibrated real-time continuous PM air monitors in controlled 5-hour experiments to measure fine particle concentrations in the 9 rooms of a detached, two-story, 4-bedroom home with either a tobacco cigarette or a marijuana joint fully smoked in the home's living room.

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We conducted 35 experiments for spatial measurement of marijuana aerosols in a current smoker's residential spaces. Fine particulate matter (PM) concentrations were measured every second at 1, 2, and 3 m horizontal distances from the smoker who performed prescribed 5-min smoking and vaping activities. In each experiment, five SidePak monitors measured PM concentrations at five different angles facing the front of the smoker, representing the worst-case exposures.

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YKL-40, a secreted glycoprotein, may serve as an autoantigen, which mediates multiple inflammatory diseases and cancers. A high YKL-40 serum level is correlated with metastasis and poor survival in a variety of human cancers. However, the role of YKL-40 in dogs is still under evaluation.

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This study introduces a cyclical annealing technique that enhances the reliability of amorphous indium-gallium-zinc-oxide (a-IGZO) via-type structure thin film transistors (TFTs). By utilizing this treatment, negative gate-bias illumination stress (NBIS)-induced instabilities can be effectively alleviated. The cyclical annealing provides several cooling steps, which are exothermic processes that can form stronger ionic bonds.

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Objective: Epidemiologic studies indicate that indoor air pollution is correlated with morbidity caused by allergic diseases. We evaluated the effectiveness of reducing the levels of indoor fine particulate matter <2.5 micrometer diameter (PM) in Fresno, California using air purifiers on health outcomes in children with asthma and/or allergic rhinitis.

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Article Synopsis
  • G-protein-coupled bile acid receptor 1 (TGR5) is linked to glucose regulation, with previous studies showing that TGR5 activation can help lower blood sugar levels through incretin secretion.
  • Betulinic acid, found in white birch leaves, has shown potential as a TGR5 agonist, and this study is the first to confirm its direct activation of TGR5.
  • Results indicate that betulinic acid enhances glucose uptake and incretin secretion in specific cell lines, reaffirming its role as a potential therapeutic agent for TGR5 activation.
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Most casinos owned by sovereign American Indian nations allow smoking, even in U.S. states such as California where state laws restrict workplace smoking.

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Real-time particle monitors are essential for accurately estimating exposure to fine particles indoors. However, many such monitors tend to be prohibitively expensive for some applications, such as a tenant or homeowner curious about the quality of the air in their home. A lower cost version (the Dylos Air Quality Monitor) has recently been introduced, but it requires appropriate calibration to reflect the mass concentration units required for exposure assessment.

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Aim: Diabetic nephropathy is the leading cause of end stage renal disease in developed countries throughout the world. The imbalance between the production of reactive oxygen species (ROS) and the antioxidant defense system is the main problem that is responsible for the progression of diabetic kidney disease. In this study, we investigated whether human extracellular superoxide dismutase (hEC-SOD) can prevent diabetic nephropathy in the rat model.

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Unlabelled: As indoor smoking bans have become widely adopted, some U.S. communities are considering restricting smoking outdoors, creating a need for measurements of air pollution near smokers outdoors.

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For an actively emitting source such as cooking or smoking, indoor measurements have shown a strong "proximity effect" within 1 m. The significant increase in both the magnitude and variation of concentration near a source is attributable to transient high peaks that occur sporadically-and these "microplumes" cause great uncertainty in estimating personal exposure. Recent field studies in naturally ventilated rooms show that close-proximity concentrations are approximately lognormally distributed.

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Indoor sources can greatly contribute to personal exposure to particulate matter less than 2.5 μm in diameter (PM2.5).

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Unlabelled: This study considers a laboratory examination of the antioxidant performance of methanolic extracts from the leaves and stems of 3 common wild grapes (Vitis thunbergii, V. flexuosa, and V. kelungeusis) by various in vitro methods.

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Personal exposure to air pollutants can be substantially higher in close proximity to an active source due to non-instantaneous mixing of emissions. The research presented in this paper quantifies this proximity effect for a non-buoyant source in 2 naturally ventilated homes in Northern California (CA), assessing its spatial and temporal variation and the influence of factors such as ventilation rate on its magnitude. To quantify how proximity to residential sources of indoor air pollutants affects human exposure, we performed 16 separate monitoring experiments in the living rooms of two detached single-family homes.

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The amount of light scattered by airborne particles inside an aerosol photometer will vary not only with the mass concentration, but also with particle properties such as size, shape, and composition. This study conducted controlled experiments to compare the measurements of a real-time photometer, the SidePak AM510 monitor (SidePak), with gravimetric mass. PM sources tested were outdoor aerosols, and four indoor combustion sources: cigarettes, incense, wood chips, and toasting bread.

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For modeling exposure close to an indoor air pollution source, an isotropic turbulent diffusion coefficient is used to represent the average spread of emissions. However, its magnitude indoors has been difficult to assess experimentally due to limitations in the number of monitors available. We used 30-37 real-time monitors to simultaneously measure CO at different angles and distances from a continuous indoor point source.

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Smoking bans often exempt casinos, exposing occupants to fine particles (PM(2.5)) from secondhand smoke. We quantified the relative contributions to PM(2.

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Electrochemical sensors are commonly used to measure concentrations of gaseous air pollutants in real time, especially for personal exposure investigations. The monitors are small, portable, and have suitable response times for estimating time-averaged concentrations. However, for transient exposures to air pollutants lasting only seconds to minutes, a non-instantaneous time response can cause measured values to diverge from actual input concentrations, especially when the pollutant fluctuations are pronounced and rapid.

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Despite California's 1994 statewide smoking ban, exposure to secondhand smoke (SHS) continues in California's Indian casinos. Few data are available on exposure to airborne fine particles (PM₂.₅) in casinos, especially on a statewide basis.

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A new triple filter system sampler/model is proposed for the precise and accurate simultaneous sampling and determination of gas- and aerosol-phase 2,4-toluene diisocyanate (TDI). The system consists of two front Teflon filters for sampling aerosol-phase TDI and a final coated glass fiber filter to collect gas-phase TDI. The aerosol-phase TDI is collected on the first Teflon filter, while the second Teflon filter is used to estimate gaseous TDI adsorbed by the first.

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