Ivanov M.G.,Ural Federal University |
Ivanov D.M.,Ural Federal University |
Pavlyshko S.V.,Russian Academy of Sciences |
Petrov I.,SKN |
And 3 more authors.
Fullerenes Nanotubes and Carbon Nanostructures | Year: 2012
In the current paper, it is demonstrated that nanoadditives based on detonation nanodiamonds used in combination with other antifriction\antiwear additives provide from modest to significant improvements of the tribological properties of the commercial lubricating oils depending on the initial formulated oil properties. It was also demonstrated that functionalization of DND surface with fluorine provides beneficial effect. Fluorine-containing DNDs demonstrated superior tribological properties as compared to the pristine non-functionalized particles. © 2012 Copyright Taylor and Francis Group, LLC.
Petrova N.,South Ural State University |
Zhukov A.,Saint Petersburg State University |
Gareeva F.,Saint Petersburg State University |
Koscheev A.,Karpov Institute of Physical Chemistry |
And 2 more authors.
Diamond and Related Materials | Year: 2012
The electrophoretic mobility of nanodiamond (ND) particles measured using laser Doppler electrophoresis in LiCl, NaCl, KCl and CsCl aqueous solutions is reported. The nanodiamond samples included porous aggregates of detonation nanodiamond (DND) particles, completely disaggregated single-digit DND and monolithic 50 nm particles of static high-pressure high-temperature (HPHT) synthesis. Corresponding values of ζ-potential were calculated as functions of electrolyte concentration using different theory of electrophoresis. The use of the Miller formula, which takes into account the electromigration fluxes of ions and electroosmotic flows of solutions in pores of dispersed particles, was found to provide the most accurate ζ-potential values for DND aggregates, while for monolithic ND particles Ohshima's approximation developed for the arbitrary zeta potential value and the Debye length/particle radius ratio is more appropriate. © 2012 Elsevier B.V. All rights reserved.
Ivanov M.G.,Ural State Technical University |
Pavlyshko S.V.,Russian Academy of Sciences |
Ivanov D.M.,Ural State Technical University |
Petrov I.,SKN |
Shenderova O.,International Technology Center
Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics | Year: 2010
Results of tribological testing of stable colloidal dispersions of detonation nanodiamond (DND) in combination with other lubricant additives in mineral oil, greases as well as in polyalphaolefin (PAO) oil are reported. The synergistic effect of combining DND with polytetrafluoroethylene (PTFE), copper nanoparticles or a commercial additive Vanlube (non-phosphor containing anti-wear additive) is reported. Testing of the formulations using ring-on-ring, shaft/bushing and four ball test techniques was performed. The test results reveal more than 80-90% decrease of friction coefficient, about 50% decrease of a diameter of wear spot as well as several times increase of extreme pressure failure load for certain formulations. A strong synergistic effect when using a combination of DND/PTFE additives was observed by a sharp decrease of friction coefficient. It was also demonstrated that the use of smaller DND aggregate size (10nm versus 120nm) resulted in better lubricating performance of PAO-based oil formulation. © 2010 American Vacuum Society.
Bednarska-Czerwinska A.,Gyncentrum Klinika Leczenia Nieplodnosci i Diagnostyki Prenatalnej w Katowicach |
Mercik D.,Gyncentrum Klinika Leczenia Nieplodnosci i Diagnostyki Prenatalnej w Katowicach |
Ginekologia i Poloznictwo | Year: 2015
This paper discusses significant elements that make up the decidualization of the endometrium which renders this tissue capable of embryo implantation, i.e. makes it receptive. Subsequ- ently, angiogenesis, penetration of the endometrium by macrophages, immune polarization and the problem or maternal immune tolerance to the embryo are discussed. A significant element for effective implantation is the site where the apical layer of the decidua communicates with the outer surfaces of the embryo. This communication is facilitated or prevented by adhesion molecules present in the endometrium. Leukemia inhibitory factor (LIF) and its receptor are particularly emphasized. Other markers mentioned in the paper are: mucin (MUC1), glyco- delin A, integrins, L-selectin, interleukins (IL-1 and IL-6), E-cadherin and cyclin. Finally, a search for genetic markers of endometrial receptivity and the role of HOXA-10 and HOXA- 11 genes are presented. © GinPolMedProject.
USC's Sean Curran observed the phenomenon in the worm species C. elegans, but the cellular mechanisms associated with it also exist in humans, raising the possibility that we may share this trait as well. When an organism is exposed to external stresses such as famine, a protein that protects cells called SKN-1 is activated. In addition to stress resistance, activation of SKN-1 also drives the reallocation of lipids from the organism's soma, or bodily cells, to its germline, or reproductive system, Curran found. Once there, the fats fuel the development of oocytes, or egg cells, making successful reproduction easier; however, the animal itself faces a higher likelihood of a shortened lifespan. (Most C. elegans are hermaphrodites—Curran is still exploring whether the phenomenon also occurs with the male portion of the worm's reproductive system.) When the organism again obtains nutrients, the presence of omega-3 and -6 fatty acids stop the travel of fats into the reproductive cells, bringing the animal's ability to resist environmental stressors back to normal. "SKN-1 plays essential roles in survival to stress at all stages in life; however, SKN-1 activation mutants are not long-lived. This is incredibly surprising and confusing at the same time since these animals should be stress resistant," said Curran, assistant professor with joint appointments at the USC Davis School of Gerontology and the USC Dornsife College of Letters, Arts and Sciences. "Our study shows that the reason constitutively active SKN-1 doesn't confer longevity because of the movement of lipids from the soma to the germline to promote the necessity of reproduction." Curran is the senior author of a study on the mechanism, which will be published by Proceedings of the National Academy of Sciences on November 30, 2015. His collaborators include researchers from USC, Baylor College of Medicine, and Massachusetts General Hospital. The researchers looked at stored fat molecules within the worms visually by staining cells and biochemically with gas chromatography and mass spectrometry. The animals underwent stress from starvation and calorie restriction as well as oxidative stress from hydrogen peroxide exposure. Oxidative stresses - an overload of reactive oxygen molecules that has been associated with cancer - can also trigger the activation of SKN-1. Since all organisms that require oxygen have to respond to oxidative stress, an understanding of how oxidative stress responses impact reproduction and vice versa is likely to yield more insights into how survival and reproduction balance against each other depending on resource availability, Curran says. "This is particularly important in the wild, where resource availability is highly variable, and unlike in the laboratory, animals in nature must constantly assess possible risk and future reward," he explains. Curran is subsequently exploring the signaling mechanisms underlying this fat reallocation and the environmental triggers of the response. Since everything his team has found so far that regulates SKN-1 in worms has also been identified in humans and the balance of somatic resistance and reproduction is important for all organisms, the findings could have implications for reproductive success in older humans, he says. Explore further: Joslin researchers discover new effect for insulin More information: Omega-3 and -6 fatty acids allocate somatic and germline lipids to ensure fitness during nutrient and oxidative stress in Caenorhabditis elegans, PNAS, www.pnas.org/cgi/doi/10.1073/pnas.1514012112 Journal reference: Proceedings of the National Academy of Sciences