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1.
Siwak Christina T.; Tapp P. Dwight; Zicker Steven C.; Murphey Heather L.; Muggenburg Bruce A.; Head Elizabeth; Cotman Carl W.; Milgram Norton W. 《Canadian Metallurgical Quarterly》2003,117(4):813
Beagle dogs exhibited diurnal patterns of locomotor activity that varied as a function of age, cognitive status, and housing environment. Aged dogs housed in an indoor facility showed a delayed onset of activity following lights on and displayed shorter bouts of activity, with more rest periods during the day, compared with young dogs. Cognitively impaired aged dogs were more active and showed a delayed peak of activity compared with unimpaired aged dogs. Housing in continuous light did not disrupt activity rhythms. The effect of age was less prominent in dogs housed in an indoor/outdoor facility. This suggests that bright sunlight and natural light-dark transitions are better able to consolidate and synchronize the activity rhythms of the dogs. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
2.
Mateusz Sopata Siwak Piotr Adamek Grzegorz Jakubowicz Jaroslaw 《Protection of Metals and Physical Chemistry of Surfaces》2020,56(4):759-765
Protection of Metals and Physical Chemistry of Surfaces - The nanocrystalline tantalum alloys were investigated in terms of mechanical properties. The materials were obtained by powder metallurgy... 相似文献
3.
We report the fabrication of gold/polycarbonate (Au/PC) hybrid nano resonators on plastic substrates through a nano-transfer
printing (nTP) technique, and the parametric studies of the resonant frequency of the resulting hybrid nano resonators. nTP
is a nanofabrication technique that involves an assembly process by which a printable layer can be transferred from a transfer
substrate to a device substrate. In this article, we applied nTP to fabricate Au/PC hybrid nano resonators on a PC substrate.
When an AC voltage is applied, the nano resonator can be mechanically excited when the AC frequency reaches the resonant frequency
of the nano resonator. We then performed systematic parametric studies to identify the parameters that govern the resonant
frequency of the nano resonators, using finite element method. The quantitative results for a wide range of materials and
geometries offer vital guidance to design hybrid nano resonators with a tunable resonant frequency in a range of more than
three orders of magnitude (e.g., 10 KHz-100 MHz). Such nano resonators could find their potential applications in nano electromechanical
devices. Fabricating hybrid nano resonators via nTP further demonstrates nTP as a potential fabrication technique to enable
a low-cost and scalable roll-to-roll printing process of nanodevices. 相似文献
4.
P. A. Andreani J. C. Benezet E. Garcia-Diaz J. M. Siwak A. Benhassaine 《Powder Technology》2003,130(1-3):84-90
The aim of this work is to study the organisation of the distributed system and the influence of adsorption and agglomeration phenomena in a dry bi-phase mixture. The studied system is a mixture of silica and carbonate. The parameter of interest is particle size. With the crossover of different fractions of silica and carbonate, it is possible to build a dimensional chessboard and then study the role of dimension in the organisation of distributed system. In these mixtures, several combinations are possible following the particle size. These combinations result from agglomeration and adsorption mechanisms. It is necessary to distinguish self-attractive phenomena (self-agglomeration and self-adsorption) that concern particles of same chemical composition, and inter-attractive phenomena (inter-agglomeration and inter-adsorption) that concern particles of different chemical compositions. The reactivity of the different mixtures treated thermally at 850 °C is measured by X-ray diffraction (DRX). It is estimated by the quantity of produced phases. Then this reactivity is explained by the different attractive phenomena studied. 相似文献
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Spark plasma sintering (SPS) has been used to successfully densify a 7075 aluminium alloy obtained from Alumix 431 powder. Sintering experiments were conducted at the temperature of 450 and 500°C for 2.5, 5 and 10?min. All the presented results confirm the excellent sinterability of Alumix 431 powder in vacuum during the SPS process and clearly show the effect of sintering temperatures and holding times on the densification, microstructure and mechanical properties of the obtained sintered compacts. The best results of hardness (1412?±?39?MPa), tensile strength (345?±?15?MPa) and compressive strength (618?±?4?MPa) were obtained by the compacts sintered at 500°C for 5 min. 相似文献
7.
Jakubowicz J. Adamek G. Siwak P. Palka K. Jurczyk M. U. Wirstlein P. K. Pilch M. Dewidar M. 《Protection of Metals and Physical Chemistry of Surfaces》2019,55(6):1124-1133
Protection of Metals and Physical Chemistry of Surfaces - The paper presents mechanical properties of the porous Ti scaffold made with saccharose as a space holder. The Ti scaffolds had the... 相似文献
8.
Plant polyphenols, such as flavonoids, are ubiquitous components of human diet, and have been recognised as efficient radical scavengers and antioxidants. Their protective effects were especially seen in cell-free assays. Whilst in living cells, depending on experimental conditions, polyphenols may manifest both anti- and pro-oxidative activity. In the present study, the effectiveness of fifteen structurally different flavonoids against hypochlorite-mediated changes in in vitro systems, with and without cells, was tested and compared. Quercetin was found to be the best protector against hypochlorite-mediated fluorescein bleaching and BSA thiol groups oxidation, whilst in living cells its effects on hypochlorite-associated cytotoxicity were moderate. Contrary, epigallocatechin gallate, pelargonidin and catechin, with less impressive hypochlorite scavenging activity in cell-free assays, were the most effective against 3-chlorotyrosine formation after hypochlorite treatment. Taken together, special care should be taken when extrapolating the results on antioxidant propensity of food bioactive compounds in vitro to the cellular milieu. 相似文献
9.
HH Birdsall J Trial HJ Lin DM Green GW Sorrentino EB Siwak AL de Jong RD Rossen 《Canadian Metallurgical Quarterly》1997,158(12):5968-5977
To identify factors that cause HIV-1 to establish perivascular foci of infected cells, we studied the transendothelial migration of blood mononuclear leukocytes (MNL) from 76 HIV+ patients and 41 controls. The fraction of patients' lymphocytes that migrated across endothelial cell monolayers in vitro was significantly increased (p < or = 0.03) compared with that of control donors. Migration of patients' CD4+ T cells was particularly enhanced, whereas the migration of monocytes did not differ between patients and controls. Lymphocyte migration correlated with expression of CD11a/CD18 and CD49d/CD29 and with the quantity of TNF-alpha produced as MNLs migrated through the endothelium. Measurement of HIV-1 proviral DNA copies in the patients' MNLs (n = 26) suggested that in half the cases virus-infected cells accumulated preferentially amidst the migratory leukocytes. We observed the same behavior with normal donor MNLs infected, in vitro, with each of 4 strains of HIV-1. The number of HIV-1 proviral DNA copies per million MNLs was 40 to 178 times higher in the migratory population than in the original population added to the endothelium. To test whether only certain strains of HIV-1 stimulate transendothelial migration of infected cells, we used single strand conformation polymorphism analysis to identify quasispecies of HIV-1 in the MNLs. If all strains of HIV-1 were equal in their ability to stimulate transendothelial migration, we expected to find no differences in the quasispecies present in the original and migratory cell populations. In fact the quasispecies differed in 14 of 19 paired samples, suggesting that only certain HIV-1 quasispecies promote transendothelial migration of infected cells. 相似文献
10.
WA Scott D Brambilla E Siwak C Beatty J Bremer RW Coombs H Farzadegan SA Fiscus SM Hammer FB Hollinger N Khan S Rasheed PS Reichelderfer 《Canadian Metallurgical Quarterly》1996,34(9):2312-2315
Quantitative microculture assays of cryopreserved human immunodeficiency virus type 1-infected cell suspensions and culture supernatants were compared among seven assays sites. There was no significant change in titer during 1 year of storage. The overall standard deviation for infected cell suspensions was approximately 0.8 log10 virus titer. A method for detecting deviant assay results was developed and was used to identify two donor cell preparations (n = 54) that gave consistently low titers. 相似文献