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51.
The structure of a two-dimensional film formed by adsorbed polymer chains was studied by means of Monte Carlo simulations. The polymer chains were represented by linear sequences of lattice beads and positions of these beads were restricted to vertices of a two-dimensional square lattice. Two different Monte Carlo methods were employed to determine the properties of the model system. The first was the random sequential adsorption (RSA) and the second one was based on Monte Carlo simulations with a Verdier-Stockmayer sampling algorithm. The methodology concerning the determination of the percolation thresholds for an infinite chain system was discussed. The influence of the chain length on both thresholds was presented and discussed. It was shown that the RSA method gave considerably lower thresholds for longer chains. This behavior can be explained by a different pool of chain conformations used in the calculations in both methods under consideration. Figure
The percolation cluster (in red) in the system consisting of long flexible chains 相似文献
52.
The biospeckle phenomenon is used for non-destructive monitoring the quality of fresh fruits and vegetables, but in the case of plant tissues there is a lack of experimentally confirmed information about the biological origin of the biospeckle activity (BA). As a main sources of BA, processes associated with the movement inside the cell, such as cytoplasmic streaming, organelle movement and intra- and extracellular transport mechanisms, are considered. The aim of this study is to investigate the effect of metabolism inhibitors, connected with intracellular movement such as cytochalasin B, lantrunculin B, colchicine, cycloheximid, dimethyl sulfoxide (DMSO) and mixture of ion channel inhibitors, injected into apples, on BA. Two methods of BA analysis based on cross-correlation coefficient and Laser Speckle Contrast Analysis (LASCA) were used. DMSO, lantrunculin B and mixture of ion channel inhibitors have a significant effect on BA, and approximately 74 % of BA of apple tissue is potentially caused by biological processes. Results indicate that the functioning of actin microfilaments and ion channels significantly affect BA. 相似文献
53.
Andrzej Matyja Krzysztof Gil Artur Pasternak Krystyna Sztefko Mariusz Gajda Krzysztof A. Tomaszewski Maciej Matyja Jerzy A. Walocha Jan Kulig Piotr Thor 《Journal of cellular and molecular medicine》2013,17(6):734-742
The major mechanisms of gallstone formation include biliary cholesterol hypersecretion, supersaturation and crystallization, mucus hypersecretion, gel formation and bile stasis. Gallbladder hypomotility seems to be a key event that triggers the precipitation of cholesterol microcrystals from supersaturated lithogenic bile. Telocytes, a new type of interstitial cells, have been recently identified in many organs, including gallbladder. Considering telocyte functions, it is presumed that these cells might be involved in the signalling processes. The purpose of this study was to correlate the quantity of telocytes in the gallbladder with the lithogenicity of bile. Gallbladder specimens were collected from 24 patients who underwent elective laparoscopic cholecystectomy for symptomatic gallstone disease. The control group consisted of 25 consecutive patients who received elective treatment for pancreatic head tumours. Telocytes were visualized in paraffin sections of gallbladders with double immunofluorescence using primary antibodies against c‐Kit (anti‐CD117) and anti‐mast cell tryptase. Cholesterol, phospholipid and bile acid levels were measured in gallbladder bile. The number of telocytes in the gallbladder wall was significantly lower in the study group than that in the control group (3.03 ± 1.43 versus 6.34 ± 1.66 cell/field of view in the muscularis propria, P < 0.001) and correlated with a significant increase in the cholesterol saturation index. The glycocholic and taurocholic acid levels were significantly elevated in the control subjects compared with the study group. The results suggest that bile composition may play an important role in the reduction in telocytes density in the gallbladder. 相似文献
54.
Patryk Czortek Anna Delimat Marcin K. Dyderski Antoni Zięba Andrzej M. Jagodziński Bogdan Jaroszewicz 《Nordic Journal of Botany》2020,38(5)
The ability for vegetative growth and development of generative organs often reflects an adaptation to the environment and may be a suitable proxy for understanding population dynamics of rare relict species. An example of such a plant is Carex lachenalii Schkuhr, an arctic-alpine species, in the temperate zone of Europe only occurring in isolated localities of high-elevation mountain ranges. We aimed to assess whether there were relationships between flower production and clonal growth of C. lachenalii, both at the tuft and plot level, and how co-occurring vegetation could modify this relationship. In the study we focused on population-level traits of C. lachenalii, vegetation traits and components of functional diversity. At the tuft level we found that the proportion of flowering ramets of C. lachenalii decreased with increasing diameter of the tuft. At the plot level, in snowbed vegetation C. lachenalii produced more flowering ramets. We suggest this is due to higher environmental stress, expressed by high importance of habitat filtering (low functional dispersion) in shaping species composition of co-occurring vegetation. In granite grasslands and milder environment (expressed by higher functional dispersion), C. lachenalii produced more vegetative ramets, which we suggest is a result of a more competitive environment. While in snowbeds investment in flowering ramets could promote successful persistence of C. lachenalii, survival of subpopulations occurring in the highly competitive conditions of granite grasslands may be uncertain due to potentially weak adaptation to competition with graminoids and dwarf shrubs. 相似文献
55.
Sega Paweł Kruszka Katarzyna Szewc Łukasz Szweykowska-Kulińska Zofia Pacak Andrzej 《Plant molecular biology》2020,102(1-2):73-88
Plant Molecular Biology - In barley and other higher plants, phosphate homeostasis is maintained by a regulatory network involving the PHO2 (PHOSPHATE2) encoding ubiquitin-conjugating... 相似文献
56.
Chmur Magdalena Bajguz Andrzej Piotrowska-Niczyporuk Alicja 《Journal of Plant Growth Regulation》2020,39(4):1518-1530
Journal of Plant Growth Regulation - Wolffia arrhiza (L.) Horkel ex Wimm. is an aquatic plant belonging to the Lemnaceae family. It does not have leaves, stems, and roots, flowers rarely occur,... 相似文献
57.
Ewelina Węglarz-Tomczak Marcin Poręba Anna Byzia Łukasz Berlicki Bogusław Nocek Rory Mulligan Andrzej Joachimiak Marcin Drąg Artur Mucha 《Biochimie》2013
Neisseria meningitides is a gram-negative diplococcus bacterium and is the main causative agent of meningitis and other meningococcal diseases. Alanine aminopeptidase from N. meningitides (NmAPN) belongs to the family of metallo-exopeptidase enzymes, which catalyze the removal of amino acids from the N-terminus of peptides and proteins, and are found among all the kingdoms of life. NmAPN is suggested to be mostly responsible for proteolysis and nutrition delivery, similar to the orthologs from other bacteria. 相似文献
58.
59.
Andrzej Zawal 《水生昆虫》2013,35(1):59-66
The morphology of the larval stages of Arrenurus nobilis and A. robustus is described. Particular attention is given to characters that help to distinguish the two species, and to characters defining the subgenus Arrenurus s. str. The larva of A. robustus resembles the larvae of A. papillator and A. pustulator regarding the shape of dorsal plate, excretory pore plate, coxal plate median margins ratios, and the presence of the IIITa8 seta. The shape of the excretory pore plate in A. nobilis resembles the one in Arrenurus (Megaluracarus) mediorotundatus. The shape of dorsal plate and chelicerae is similar to the ones in the Megaluracarus-species A. globator and A. tubulator. The lack of the IIITa8 seta differs from other species of the subgenus Arrenurus s. str. In the pectinate Lp2 and Mh1 setae A. nobilis resembles representatives of the subgenus Arrenurus s. str. This demonstrates the necessity of verifying the taxonomic status of A. nobilis. 相似文献
60.
Kazima Saira Xudong Lin Jay V. DePasse Rebecca Halpin Alan Twaddle Timothy Stockwell Brian Angus Alessandro Cozzi-Lepri Marina Delfino Vivien Dugan Dominic E. Dwyer Matthew Freiberg Andrzej Horban Marcelo Losso Ruth Lynfield Deborah N. Wentworth Edward C. Holmes Richard Davey David E. Wentworth Elodie Ghedin 《Journal of virology》2013,87(14):8064-8074
Influenza virus defective interfering (DI) particles are naturally occurring noninfectious virions typically generated during in vitro serial passages in cell culture of the virus at a high multiplicity of infection. DI particles are recognized for the role they play in inhibiting viral replication and for the impact they have on the production of infectious virions. To date, influenza virus DI particles have been reported primarily as a phenomenon of cell culture and in experimentally infected embryonated chicken eggs. They have also been isolated from a respiratory infection of chickens. Using a sequencing approach, we characterize several subgenomic viral RNAs from human nasopharyngeal specimens infected with the influenza A(H1N1)pdm09 virus. The distribution of these in vivo-derived DI-like RNAs was similar to that of in vitro DIs, with the majority of the defective RNAs generated from the PB2 (segment 1) of the polymerase complex, followed by PB1 and PA. The lengths of the in vivo-derived DI-like segments also are similar to those of known in vitro DIs, and the in vivo-derived DI-like segments share internal deletions of the same segments. The presence of identical DI-like RNAs in patients linked by direct contact is compatible with transmission between them. The functional role of DI-like RNAs in natural infections remains to be established. 相似文献