21 research outputs found
Measurement of Ultrafine Particles and Other Air Pollutants Emitted by Cooking Activities
Cooking emissions show a strong dependence on cooking styles and parameters. Measurements of the average ultrafine particle (UFP) concentration, PM2.5 and black carbon concentrations emitted by cooking activities ranged from 1.34 × 104 to 6.04 × 105 particles/cm3, 10.0 to 230.9 μg/m3 and 0.1 to 0.8 μg/m3, respectively. Lower UFP concentrations were observed during boiling, while higher levels were emitted during frying. The highest UFP concentrations were observed when using a gas stove at high temperature with the kitchen exhaust fan turned off. The observed UFP profiles were similar in the kitchen and in another room, with a lag of approximately 10 min
Changes in Synaptic Transmission, Calcium Current, and Neurite Growth by Perfluorinated Compounds Are Dependent on the Chain Length and Functional Group
Scientific and public concerns on perfluorinated compounds (PFCs) are increasingly growing because of their environmental persistency, bioaccumulation, and extensive distribution throughout the world. Little is known about the effects of PFCs on neural function and the underlying mechanisms. Recent evidence suggests that the toxicological effects of PFCs are closely correlated with their carbon chain lengths. In this present work, the actions of PFCs with varying chain length on cultured rat hippocampal neurons and possible action patterns were examined. Increases in the frequencies of spontaneous miniature postsynaptic current (mPSC) were commonly found in cultured neurons when perfused with PFCs. The increase of mPSC frequency was in proportion to the carbon chain length, and the potency of perfluorinated carboxylates was less pronounced than that of perfluorinated sulfonates. A comparable but less perceptible trend was also found for the amplitudes of voltage-dependent calcium current (I-ca). No regular change in pattern was observed for the effects of PFCs on activation and inactivation kinetics of I-Ca. Furthermore, prolonged treatment of PFCs inhibited the neurite growth of neurons to various degrees. Comparisons between nonfluorinated and perfluorinated analogues demonstrated that the fluorination in alkyl chain exerts stronger actions on neurons as compared to the surfactant activity. This study shows that PFCs exhibit adverse effects on cultured neurons to various extents, which is dependent on the carbon chain length and functional group attached to the fully fluorinated alkyl chain
Surface treatment of single sisal fibers with bacterial cellulose and its enhancement in fiber-polymer adhesion properties
Mechanism and Substrate-Dependent Rate-Determining Step in Palladium-Catalyzed Intramolecular Decarboxylative Coupling of Arenecarboxylic Acids with Aryl Bromides: A DFT Study
The mechanism of palladium-catalyzed
intramolecular decarboxylative
coupling of arenecarboxylic acids with aryl bromides has been studied
computationally with the aid of density functional theory. Full free-energy
profiles have been computed for all ether- and amine-containing substituted
substrates. The calculations indicate that the rate-determining step
is indeed substrate dependent, as reflected in free energy profiles;
the oxidative addition, decarboxylation, or reductive elimination
step can become the rate-determining step for the full catalytic cycle
due to the different substituents on the substrates. In addition,
we also demonstrate the preference of NCH<sub>3</sub>- over NH-containing
amine substrates for the decarboxylation process. The calculations
are in good agreement with the experimental observations
Interferon Regulatory Factors IRF5 and IRF7 Inhibit Growth and Induce Senescence in Immortal Li-Fraumeni Fibroblasts
Cytotoxic and Insecticidal Activities of Derivatives of Harmine, a Natural Insecticidal Component Isolated from Peganum harmala
Graphene Enhances Cellular Proliferation through Activating the Epidermal Growth Factor Receptor
Graphene
has promising applications in food packaging, water purification,
and detective sensors for contamination monitoring. However, the biological
effects of graphene are not fully understood. It is necessary to clarify
the potential risks of graphene exposure to humans through diverse
routes, such as foods. In the present study, graphene, as the model
nanomaterial, was used to test its potential effects on the cell proliferation
based on multiple representative cell lines, including HepG2, A549,
MCF-7, and HeLa cells. Graphene was characterized by Raman spectroscopy,
particle size analysis, atomic force microscopy, and transmission
electron microscopy. The cellular responses to graphene exposure were
evaluated using flow cytometry, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
bromide, and alamarBlue assays. Rat cerebral astrocyte cultures, as
the non-cancer cells, were used to assess the potential cytotoxicity
of graphene as well. The results showed that graphene stimulation
enhanced cell proliferation in all tested cell cultures and the highest
elevation in cell growth was up to 60%. A western blot assay showed
that the expression of epidermal growth factor (EGF) was upregulated
upon graphene treatment. The phosphorylation of EGF receptor (EGFR)
and the downstream proteins, ShC and extracellular regulating kinase
(ERK), were remarkably induced, indicating that the activation of
the mitogen-activated protein kinase (MAPK)/ERK signaling pathway
was triggered. The activation of PI3 kinase p85 and AKT showed that
the PI3K/AKT signaling pathway was also involved in graphene-induced
cell proliferation, causing the increase of cell ratios in the G2/M
phase. No influences on cell apoptosis were observed in graphene-treated
cells when compared to the negative controls, proving the low cytotoxicity
of this emerging nanomaterial. The findings in this study revealed
the potential cellular biological effect of graphene, which may give
useful hints on its biosafety evaluation and the further exploration
of the bioapplication