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131.
Miloslav Belka Frantisek Lizal Jan Jedelsky Pavel Starha Hana Druckmullerova Philip K. Hopke 《Aerosol science and technology》2016,50(4):353-362
Man-made vitreous fibers (MMVFs) are noncrystalline substances made of glass, rock or slag and are widely used as thermal or acoustic insulation materials. There is continued concern about their potential health impacts and thus, their dosimetry and behavior in the environment still require study using filters to collect fiber samples. After deposition or exposure measurements of MMVFs it is often necessary to analyze the filters with deposited fibers. This task is tedious, time-consuming, and requires skill. Therefore, many researchers have tried to simplify or automatize fiber detection and quantification. This article describes features of our in-house software, which automatically detects and counts fibers in images of filter samples. The image analysis is based on the use of a histogram equalization and an adaptive radial convolution filter that enhances fiber contrast and thus, improves the fiber identification. The accuracy of the software analysis was verified by comparison with manual counting using ordinary phase-contrast microscopy method. The correlation between the methods was very high (coefficient of determination was 0.977). However, there were some discrepancies caused by false identifications, which led to implementation of manual corrective functions.
Copyright © 2016 American Association for Aerosol Research 相似文献
132.
Hana Jung Eunjoo H. Lee Tae Hoon Lee Man-Ho Cho 《International journal of molecular sciences》2016,17(9)
Solar ultraviolet (UV) radiation is a main extrinsic factor for skin aging. Chronic exposure of the skin to UV radiation causes the induction of matrix metalloproteinases (MMPs), such as MMP-1, and consequently results in alterations of the extracellular matrix (ECM) and skin photoaging. Flavonoids are considered as potent anti-photoaging agents due to their UV-absorbing and antioxidant properties and inhibitory activity against UV-mediated MMP induction. To identify anti-photoaging agents, in the present study we examined the preventative effect of methoxyflavonoids, such as sakuranetin, isosakuranetin, homoeriodictyol, genkwanin, chrysoeriol and syringetin, on UV-B-induced skin photo-damage. Of the examined methoxyflavonoids, pretreatment with isosakuranetin strongly suppressed the UV-B-mediated induction of MMP-1 in human keratinocytes in a concentration-dependent manner. Isosakuranetin inhibited UV-B-induced phosphorylation of mitogen-activated protein kinase (MAPK) signaling components, ERK1/2, JNK1/2 and p38 proteins. This result suggests that the ERK1/2 kinase pathways likely contribute to the inhibitory effects of isosakuranetin on UV-induced MMP-1 production in human keratinocytes. Isosakuranetin also prevented UV-B-induced degradation of type-1 collagen in human dermal fibroblast cells. Taken together, our findings suggest that isosakuranetin has the potential for development as a protective agent for skin photoaging through the inhibition of UV-induced MMP-1 production and collagen degradation. 相似文献
133.
Hana Choi BongSoo Kim Min Jae Ko Doh-Kwon Lee Honggon Kim Sung Hyun Kim Kyungkon Kim 《Organic Electronics》2012,13(6):959-968
Tungsten oxide layer is formed uniformly by a sol–gel technique on top of indium tin oxide as a neutral and photo-stable hole extraction layer (HEL). The solution processed tungsten oxide layer (sWO3) is fully characterized by UV–Vis, XPS, UPS, XRD, AFM, and TEM. Optical transmission of ITO/sWO3 substrates is nearly identical to ITOs. In addition, the sWO3 layer induces nearly ohmic contact to P3HT as PEDOT:PSS layer does, which is determined by UPS measurement. In case that an optimized thickness (~10 nm) of the sWO3 layer is incorporated in the organic photovoltaic devices (OPVs) with a structure of ITO/sWO3/P3HT:PCBM/Al, the power conversion efficiency (PCE) is 3.4%, comparable to that of devices utilizing PEDOT:PSS as HEL. Furthermore, the stability of OPV utilizing sWO3 is significantly enhanced due to the air- and photo-stability of the sWO3 layer itself. PCEs are decreased to 40% and 0% of initial values, when PEDOT:PSS layers are exposed to air and light for 192 h, respectively. In contrast, PCEs are maintained to 90% and 87% of initial PCEs respectively, when sWO3 layers are exposed to the same conditions. Conclusively, we find that solution processed tungsten oxide layers can be prepared easily, act as an efficient hole extraction layer, and afford a much higher stability than PEDOT:PSS layers. 相似文献
134.
135.
Hana Kubatova Eva Zemanova Karel Klouda Karel Bilek Jana Kadukova 《材料科学与工程:中英文B版...》2013,(7):409-417
The contribution deals with preparation of C50 fullerene derivatives (oxo derivative, bromo derivative, hydrolyzed bromoderivative, bromo-chloro derivative), their identification and pilot testing of their biological effects on unicellular organisms. The contribution describes effects of C60 fullerene derivatives, both on prokaryotic organisms (bacteria, cyanobacteria) and eukaryotic organisms (algae) and assesses their potential use as biocides. 相似文献
136.
1H NMR spectroscopy was used to investigate the temperature-induced phase transitions in aqueous solutions of poly(N-isopropylmethacrylamide)/poly(N-vinylcaprolactam) (PIPMAm/PVCL) mixtures to find out if the phase transition of the given component (PIPMAm or PVCL) is affected by the presence of the second component. Our results that PVCL and PIPMAm transitions are in polymer mixtures shifted by ~2 K towards higher temperatures in comparison with neat polymers and depend on polymer concentration show that such effect exists. Spin–spin relaxation times of water (HDO) indicate that in solutions with c ≥ 1 wt% a portion of water is predominantly bound in PVCL mesoglobules even at temperatures above the LCST transition of PIPMAm component. Water is with time released from these mesoglobules without any induction period so indicating that it is mostly indirectly bound water. We assume that there is a direct connection between character of the bound water and the transition temperatures. 相似文献
137.
Olive leaves are commercialized for their antioxidative value due to their valuable phenolic compounds. The present study aimed to evaluate the effect of gamma irradiation on microbial load, on antioxidative properties and on phenolic compounds of air-dried olive leaves. Irradiation was applied up to 25 kGy (5 kGy intervals) to powdered and intact samples. Total aerobic bacteria, yeast and mold, and lactic acid bacteria were counted after gamma irradiation. Decontamination was obtained at 20 kGy. The radioresistance of microbial population was high with D10 values between 9.74 and 25.12 kGy. Besides, gamma irradiation up to 25 kGy was found to maintain the antioxidant capacity, molecular mass distribution of polyphenolics, total phenolics, ortho-diphenols, flavonoids, oleuropein, verbascoside and rutin contents. 相似文献
138.
Ondrej Chlumsky Sabina Purkrtova Hana Michova Hana Sykorova Petr Slepicka Dominik Fajstavr Pavel Ulbrich Jitka Viktorova Katerina Demnerova 《International journal of molecular sciences》2021,22(15)
Although some metallic nanoparticles (NPs) are commonly used in the food processing plants as nanomaterials for food packaging, or as coatings on the food handling equipment, little is known about antimicrobial properties of palladium (PdNPs) and platinum (PtNPs) nanoparticles and their potential use in the food industry. In this study, common food-borne pathogens Salmonella enterica Infantis, Escherichia coli, Listeria monocytogenes and Staphylococcus aureus were tested. Both NPs reduced viable cells with the log10 CFU reduction of 0.3–2.4 (PdNPs) and 0.8–2.0 (PtNPs), average inhibitory rates of 55.2–99% for PdNPs and of 83.8–99% for PtNPs. However, both NPs seemed to be less effective for biofilm formation and its reduction. The most effective concentrations were evaluated to be 22.25–44.5 mg/L for PdNPs and 50.5–101 mg/L for PtNPs. Furthermore, the interactions of tested NPs with bacterial cell were visualized by transmission electron microscopy (TEM). TEM visualization confirmed that NPs entered bacteria and caused direct damage of the cell walls, which resulted in bacterial disruption. The in vitro cytotoxicity of individual NPs was determined in primary human renal tubular epithelial cells (HRTECs), human keratinocytes (HaCat), human dermal fibroblasts (HDFs), human epithelial kidney cells (HEK 293), and primary human coronary artery endothelial cells (HCAECs). Due to their antimicrobial properties on bacterial cells and no acute cytotoxicity, both types of NPs could potentially fight food-borne pathogens. 相似文献
139.
Cancer stem cells (CSCs) can be induced from differentiated cancer cells in the tumor microenvironment or in response to treatments and exhibit chemo- and radioresistance, leading to tumor recurrence and metastasis. We previously reported that triple negative breast cancer (TNBC) cells with acquired radioresistance exhibited more aggressive features due to an increased CSC population. Therefore, here, we isolated CSCs from radiotherapy-resistant (RT-R)-TNBC cells and investigated the effects of these CSCs on tumor progression and NK cell-mediated cytotoxicity. Compared to MDA-MB-231 and RT-R-MDA-MB-231 cells, CD24−/low/CD44+ cells isolated from RT-R-MDA-MB-231 cells showed increased proliferation, migration and invasion abilities, and induced expression of tumor progression-related molecules. Moreover, similar to MDA-MB-231 cells, CD24−/low/CD44+ cells recruited NK cells but suppressed NK cell cytotoxicity by regulating ligands for NK cell activation. In an in vivo model, CD24−/low/CD44+ cell-injected mice showed enhanced tumor progression and lung metastasis via upregulation of tumor progression-related molecules and altered host immune responses. Specifically, NK cells were recruited into the peritumoral area tumor but lost their cytotoxicity due to the altered expression of activating and inhibitory ligands on tumors. These results suggest that CSCs may cause tumor evasion of immune cells, resulting in tumor progression. 相似文献
140.
This article presents a multiscale approach to derive the interlaminar properties of graphene nanoplatelets (GNPs)-based polymeric composites reinforced by short glass fibers (SGFs) and unidirectional carbon fibers (UCFs). The approach accounts for the debonding at the interface of a 2-phases GNPs/polymer matrix using a cohesive model. The resulting composite is used within a 3-phases nanocomposite consisting either of a GNPs/polyamide/SGFs or a GNPs/epoxy/UCFs nanocomposite. Experiments are performed for determining the interlaminar fracture toughness in mode I for the GNPs/epoxy/UCFs. Results show that the aspect ratio (AR) of GNPs influences the effective Young modulus which increases until a threshold. Also, the addition of the GNPs increases up to 10% the transverse Young modulus and up to 11% the shear modulus as well as up to 16% the transverse tensile strength useful in crashworthiness performance. However, the nanocomposite behavior remains fiber dominant in the longitudinal direction. This leads to a weak variation of the mechanical properties in that direction. Due to the well-known uniform dispersion issues of GNPs, the interlaminar fracture toughness GIC has decreased up to 8.5% for simulation and up to 2.4% for experiments while no significant variation of the interlaminar stress distribution is obtained compared to a nanocomposite without GNPs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47664. 相似文献