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41.
We present an approach based on three-dimensional Monte Carlo radiative transfer simulations for estimating scattering error in measurements of light absorption by aquatic particles with a typical laboratory double-beam spectrophotometer. The scattering error is calculated by combining the weighting function describing the angular distribution of photon losses that are due to scattering on suspended particles with the volume scattering function of particles. We applied this method to absorption measurements made on marine phytoplankton, a diatom Thalassiosira pseudonana and a cyanobacterium Synechococcus. Assuming that the scattering phase function is described by the Henyey-Greenstein formula, we determined the backscatter probability of phytoplankton, which yields the best correction for scattering error at a light wavelength of 750 nm, where true absorption is null. The backscattering ratio estimated for both phytoplankton species is significantly higher than previously reported data based on Mie-scattering calculations for homogeneous spheres. Depending on the type of particles, the corrected absorption spectra obtained with our method may be similar or significantly different from spectra obtained with the null-point correction based on wavelength-independent scattering error. 相似文献
42.
Cora Chmielowska Dorota Korsak Barbara Szmulkowska Alicja Krop Kinga Lipka Martyna Krupiska Dariusz Bartosik 《International journal of molecular sciences》2020,21(22)
Listeria monocytogenes is a pathogen responsible for severe cases of food poisoning. Listeria spp. strains occurring in soil and water environments may serve as a reservoir of resistance determinants for pathogenic L. monocytogenes strains. A large collection of Listeria spp. strains (155) isolated from natural, agricultural, and urban areas was screened for resistance to heavy metals and metalloids, and the presence of resistance determinants and extrachromosomal replicons. Of the tested strains, 35% were resistant to cadmium and 17% to arsenic. Sequence analysis of resistance plasmids isolated from strains of Listeria seeligeri and Listeria ivanovii, and the chromosome of L. seeligeri strain Sr73, identified a novel variant of the cadAC cadmium resistance efflux system, cadA6, that was functional in L. monocytogenes cells. The cadA6 cassette was detected in four Listeria species, including strains of L. monocytogenes, isolated from various countries and sources—environmental, food-associated, and clinical samples. This resistance cassette is harbored by four novel composite or non-composite transposons, which increases its potential for horizontal transmission. Since some cadAC cassettes may influence virulence and biofilm formation, it is important to monitor their presence in Listeria spp. strains inhabiting different environments. 相似文献
43.
Dariusz Kata Kenshiro Shirai Manshi Ohyanagi Zuhair A. Munir 《Journal of the American Ceramic Society》2001,84(4):726-732
The synthesis of solid solutions of AlN–SiC was investigated through the combustion reaction between Si3 N4 , aluminum, and carbon powders and nitrogen gas at pressures ranging from 0.1 to 6.0 MPa. The combustion reaction was initiated locally and then the wave front propagated spontaneously, passing through the cylindrical bed containing the loose powder. In the presence of Si3 N4 as a reactant, it was feasible to synthesize solid solutions at an ambient pressure (0.1 MPa). The relationship between nitrogen pressure and full-width at half-maximum of the (110) peak of the product showed that lower pressures produced more-homogeneous solid solutions. Some aspects of formation of the AlN–SiC solid solutions were discussed with special emphasis on the influence of nitrogen pressure and reactant stoichiometry. 相似文献
44.
Anna Wajler Anna Kozłowska Magdalena Nakielska Kamila Leśniewska‐Matys Agata Sidorowicz Dariusz Podniesiński Piotr Putyra 《Journal of the American Ceramic Society》2014,97(6):1692-1695
Transparent cobalt‐doped magnesium aluminate spinel (Co:MgAl2O4) ceramics with a submicrometer grain size were prepared by spark plasma sintering. For the first time, the nonlinear absorption of Co:MgAl2O4 transparent ceramics was experimentally demonstrated. Both ground state absorption (σGSA) and excited state absorption (σESA) were estimated using the solid‐state slow saturable absorber model based on absorption saturation measurements performed at 1.535 μm. σGSA and σESA for 0.03 at.% Co:MgAl2O4 were found to be 4.1 × 10?19 cm2 and 4.0 × 10?20 cm2, respectively. In the case of 0.06 at.% Co:MgAl2O4 ceramics, σGSA = 2.6 × 10?19 cm2 and σESA= 5.3 × 10?20 cm2 were determined. 相似文献
45.
Jan Korbecki Klaudyna Kojder Patrycja Kapczuk Patrycja Kupnicka Barbara Gawroska-Szklarz Izabela Gutowska Dariusz Chlubek Irena Baranowska-Bosiacka 《International journal of molecular sciences》2021,22(2)
Hypoxia is an integral component of the tumor microenvironment. Either as chronic or cycling hypoxia, it exerts a similar effect on cancer processes by activating hypoxia-inducible factor-1 (HIF-1) and nuclear factor (NF-κB), with cycling hypoxia showing a stronger proinflammatory influence. One of the systems affected by hypoxia is the CXC chemokine system. This paper reviews all available information on hypoxia-induced changes in the expression of all CXC chemokines (CXCL1, CXCL2, CXCL3, CXCL4, CXCL5, CXCL6, CXCL7, CXCL8 (IL-8), CXCL9, CXCL10, CXCL11, CXCL12 (SDF-1), CXCL13, CXCL14, CXCL15, CXCL16, CXCL17) as well as CXC chemokine receptors—CXCR1, CXCR2, CXCR3, CXCR4, CXCR5, CXCR6, CXCR7 and CXCR8. First, we present basic information on the effect of these chemoattractant cytokines on cancer processes. We then discuss the effect of hypoxia-induced changes on CXC chemokine expression on the angiogenesis, lymphangiogenesis and recruitment of various cells to the tumor niche, including myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs), regulatory T cells (Tregs) and tumor-infiltrating lymphocytes (TILs). Finally, the review summarizes data on the use of drugs targeting the CXC chemokine system in cancer therapies. 相似文献
46.
Izabela Mauch Oktawian Stachurski Paulina Kosikowska-Adamus Marta Makowska Marta Bauer Dariusz Wyrzykowski Aleksandra Ha Wojciech Kamysz Milena Deptua Micha Pikua Emilia Sikorska 《International journal of molecular sciences》2020,21(23)
Antimicrobial peptides (AMPs) constitute a promising tool in the development of novel therapeutic agents useful in a wide range of bacterial and fungal infections. Among the modifications improving pharmacokinetic and pharmacodynamic characteristics of natural AMPs, an important role is played by lipidation. This study focuses on the newly designed and synthesized lipopeptides containing multiple Lys residues or their shorter homologues with palmitic acid (C16) attached to the side chain of a residue located in the center of the peptide sequence. The approach resulted in the development of lipopeptides representing a model of surfactants with two polar headgroups. The aim of this study is to explain how variations in the length of the peptide chain or the hydrocarbon side chain of an amino acid residue modified with C16, affect biological functions of lipopeptides, their self-assembling propensity, and their mode of action. 相似文献
47.
Smolka Bogdan Malik Krystyna Malik Dariusz 《Journal of Real-Time Image Processing》2015,10(2):289-311
Journal of Real-Time Image Processing - In this paper, a novel approach to the problem of impulsive noise removal in color digital images is presented. The described switching filter is based on... 相似文献
48.
The Impact of Zeta Potential and Physicochemical Properties of TiO2‐Based Nanocomposites on Their Biological Activity 下载免费PDF全文
Agnieszka Maria Jastrzębska Patrycja Kurtycz Andrzej Olszyna Ewa Karwowska Ewa Miaśkiewicz‐Pęska Monika Załęska‐Radziwiłł Nina Doskocz Dariusz Basiak 《International Journal of Applied Ceramic Technology》2015,12(6):1157-1173
The aim of this research was to observe the relationship between zeta potential, morphology, surface area, porosity, chemical composition, and ecotoxicity of nanocomposite powders such as Au/TiO2, Ag2O/TiO2, PdO/TiO2, Ag/TiO2/SiO2, Ag/N(C)TiO2, and SiO2/TiO2 from which Ag2O/TiO2, Ag/N(C)/TiO2, and Ag/TiO2/SiO2 were exhibiting good antimicrobial properties. It was observed, that nanomaterials characterized by similar morphology and zeta potential revealed the similar toxic behavior. The samples of higher agglomeration and higher zeta potential, especially Ag/TiO2/SiO2 xerogel and TiO2/SiO2 aerogel were generally less ecotoxic to water organisms and plants. They were also not genotoxic in concentrations up to 500 and 250 mg/L, respectively. 相似文献
49.
Ozan Keysan Dariusz Olczak Markus A. Mueller 《Journal of Superconductivity and Novel Magnetism》2013,26(5):2103-2108
In this study, a new claw-pole type transverse flux superconducting generator topology is presented. The machine has a stationary superconducting field winding, which eliminates electrical brushes and cryocouplers. The machine is specifically designed for low-speed high torque applications such as large offshore wind turbines. The proposed machine is robust and has a modular structure. A 30 kW, 100 rpm prototype is planned to be manufactured to prove the concept. MgB2, YBCO, and BSSCO wires are compared in terms of wire length, operating temperature, and critical temperature. The magnetic flux penetrating into superconducting wire has been simulated using 3D FEA software. Moreover, mechanical loads are estimated and the deflections in the structure are analysed. 相似文献
50.
Stanisław Kucharski Dariusz Jarząbek 《Metallurgical and Materials Transactions A》2014,45(11):4997-5008
A study of the dependence of nanoindentation pile-up patterns on the indentation load and crystallographic orientation is presented. Three different orientations—(001), (011), and (111)—of single crystal copper were investigated. Experiments were conducted on a CSM ultra-nanoindentation tester using a Berkovich tip. The topographic images were obtained using an atomic force microscope. The evolution of pile-up patterns with different applied loads was observed. The results show that for applied loads equal to 0.45 mN and smaller the pile-up patterns do not depend on the crystallographic orientation of the indented surface; instead, they depend on the tip’s geometry. On the other hand, in the case of indentation loads bigger than 2 mN, pile-up patterns on the surfaces of (001)-, (011)-, and (111)-oriented single crystals have fourfold, twofold, and sixfold (or threefold) symmetry, respectively. An intermediate state was also reported. Furthermore, a detailed analysis of residual impressions with maximal applied loads equal to 2 mN and bigger reveals that both pile-up and sink-in patterns are present. 相似文献