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Compositionally Driven Viscometric Behaviors of poly (Alkyl methacrylates) in Lubricating Oils

Advances in Chemical Engineering and Science 2022年第2期12卷 65-86页

作者： Reid A. patterson Christopher p. Kabb David m. Nickerson Eugene pashkovski Research and Development The Lubrizol Corporation Wickliffe USA

Viscosity index (VI) and shear stability index (SSI) are standard methods used in the lubricant industry to determine temperature-viscosity dependency and resistance to product degradation, respectively. A variety of oil-soluble polymers, including poly(alkyl methacrylates) (pAmAs) are routinely used to control these properties in fully-formulated liquid lubricants. In this report, we use reversible addition-fragmentation chain transfer (RAFT) polymerization to precisely target identical degrees of polymerization in a family of pAmAs with varying lauryl, hexyl, butyl, ethyl, and methyl groups. Then, expanding on previous methodology reported in the literature, we establish structure property relationships for these pAmAs, specifically looking at how intrinsic viscosity [η] and martin interaction parameters Km relate to VI and SSI characteristics. While the intrinsic viscosity [η] is associated with the volume of macromolecules at infinite dilution, the parameter Km reflects the hydrodynamic interactions of polymer chains at actual polymer concentrations in lubricating oils. In this paper, we show that the dependence of VI on the non-dimensional concentration c/c* (or c[η]) can be presented in a form of master curve with shift factors proportional to Km that decreases with increasing size of alkyl groups. This finding implies that even in the dilute regime, the coil-expansion theory used to explain the effect of macromolecules on VI should be complemented with the idea of hydrodynamic interactions between polymer molecules that can be controlled by the choice of alkyl chains in the family of pAmAs.

关键词： Viscosity Index Shear Stability Index polymethacrylates Lubricating Oils

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S100A4 in esophageal cancer:Is this the one to blame?

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World Journal of Gastroenterology 2012年第30期18卷 3931-3935页

作者： Jianyuan Chai m mazen Jamal Laboratory of GI Injury and Cancer VA Long Beach Healthcare System Long Beach CA 90822 United States Division of Gastroenterology Department of Medicine University of California Irvine CA 92868 United States

metastasis is the main reason for cancer-related death.S100A4 is one of the key molecules involved in this *** studies have shown that overexpression of S100A4 in non-metastatic cancer cells can make them become metastatic,and knockdown of S100A4 in metastatic cancer cells can curtail their invasive nature.A study by Chen et al published in the World J Gastroenterol 18(9):915-922,2012 is a typical *** study showed in vitro and in vivo evidence that S100A4 expression level determines the invasiveness of esophageal squamous *** the fact that more than half of the cancer-related deaths are caused by malignancies derived from the digestive system and esophageal cancer is the 4th top contributor to this fraction,this study warrants more attention.

关键词： Esophageal cancer S100A4 metastasis

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mathematical model of a Hyperbolic Hydraulic Fracture with Tortuosity

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Journal of Applied mathematics and physics 2021年第5期9卷 1121-1157页

作者： m. R. R. Kgatle-maseko D. p. mason School of Computer Science and Applied mathematics DST-NRF Centre of Excellence in Mathematical and Statistical Sciences University of the Witwatersrand Johannesburg South Africa

The aim of the research is to study the propagation of a hydraulic fracture with tortuosity due to contact areas between touching asperities on opposite crack walls. The tortuous fracture is replaced by a model symmetric partially open fracture with a hyperbolic crack law and a modified Reynolds flow law. The normal stress at the crack walls is assumed to be proportional to the half-width of the model fracture. The Lie point symmetry of the nonlinear diffusion equation for the fracture half-width is derived and the general form of the group invariant solution is obtained. It was found that the fluid flux at the fracture entry cannot be prescribed arbitrarily, because it is determined by the group invariant solution and that the exponent n in the modified Reynolds flow power law must lie in the range 2 m>nm> problem is solved numerically using a backward shooting method from the fracture tip, offset by 0 m>δm> ≪ 1 to avoid singularities, to the fracture entry. The numerical results showed that the tortuosity and the pressure due to the contact regions both have the effect of increasing the fracture length. The spatial gradient of the half-width was found to be singular at the fracture tip for 3 m>nm> m>nm> = 3 and to be zero for 2 m>nm> m approximation breaks down at the fracture tip for 3 m>nm> mains valid for increasingly tortuous fractures with 2 m>nm> perities is to decrease the width averaged fluid velocity. An approximate analytical solution for the half-width, which was found to agree well with the numerical solution, is derived by making the approximation that the width averaged fluid velocity increases linearly with distance along the fracture.

关键词： Hyperbolic Crack Law partially Open Fracture with Tortuosity modified Reynolds Flow Law Backward Shooting method Approximate Analytical Solution

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Optical properties and radiative rates of Nd^(3+) doped zinc-sodium phosphate glasses

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Journal of Rare Earths 2019年第3期37卷 253-259页

作者： A.A.El-maaref Shimaa Badr Kh.S.Shaaban E.A.Abdel Wahab m.m.ElOkr physics Department Faculty of Science Al-Azhar University modern Academy for Engineering & Technology Chemistry Department Faculty of Science Al-Azhar University

preparation using melt quenching technique and optical characterizations of Nd^(3+) doped Zn-Na phosphate glasses are presented. The structure of the present glasses was studied using X-ray diffraction and FT-IR spectroscopy. UV-vis spectra of the present glasses were analyzed at different concentrations of Nd_2 O_3. The effect of neodymium concentration on the density and energy band gap was investigated. The density of the present glasses slightly increases with the increasing of Nd_2 O_3. A small variation of energy band gap with the increasing of neodymium content is observed as well, while E_g values decrease with the increase of Nd_2 O_3 content. The E_g values lie between 4.36 and 4.69 eV. Based on the measured optical spectra, Judd-Ofelt theory was used to determine the optical parameters such as line strengths, optical intensity parameters(Ω_t), transition probabilities, and transition lifetimes. Hypersensitive transitions were identified in the absorption spectrum, the greatest line strengths are recorded at the transitions^2 G_(7/2)+ ~4 G_(5/2), ~4 S_(3/2) + ~4 F_(7/2) and ~4 D_(1/2) + ~4 D_(3/2)+ ~4 D_(5/2) + ~2 I_(11/2) with wavelengths of 580, 475 and 355 nm,respectively. Lifetimes of the important ~4 F_(3/2) laser-level were determined; which show decreasing trend with the increasing of Nd_2 O_3 content and are found to be between 0.838 and 1.595 ms. The uncertainty of the present results was estimated. The RmS deviations were determined, which show lower values than those in the literature.

关键词： phosphate glass UV-vis spectroscopy Judd-Ofelt Radiative rates Rear earth ions

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Apolipoprotein B Is a Good Tool for Screening Dyslipidaemia in Apparently Healthy population

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Journal of Biosciences and medicines 2016年第5期4卷 58-64页

作者： L. V. Athiththan m. F. F. Nusha U. p. K. Hettiaratchi p. p. R. perera Department of Biochemistry University of Sri Jayewardenepura Nugegoda Sri Lanka

Dyslipidaemia is the major risk factor for cardiovascular disease (CVD) which is the leading cause of death in the world. Even though several lipid parameters are used, currently apolipoprotein B (apoB) is considered as the best predictor of CVD. Thus this study was carried out to find out the association between conventional lipid parameters and apoB in apparently healthy subjects. A descriptive cross-sectional study was carried out in 170 apparently healthy volunteers who were not diagnosed with dyslipidaemia. After 12 hours overnight fast venous blood was obtained and Total cholesterol (TC), Triglyceride (TG), High density lipoprotein cholesterol (HDL-C) were measured by enzymatic kit method. Low density lipoprotein cholesterol (LDL-C) was calculated by Friedewald formula and apoB was analyzed by immune turbid metry using a Konelabp>®p> auto analyzer. Among the participants, majority (63.5%) were females. The mean value of apoB concentration of the population was 103 ± 42 mg/dL which was similar and not significantly different between the genders (males, 102 ± 37 mg/dL and Females, 104 ± 45 mg/dL). All lipid parameters showed a positive correlation with apoB concentration whereas HDL-C had a negative correlation (r = -0.165). HDL-C significantly (p poB concentration while LDL-C, TC/HDL-C and non-HDL-C significantly (p poB concentration. present study suggests that serum apoB has better correlations and associations with the parameters that are used in conventional lipid profile and with markers recommended for diagnosing dyslipidaemia. Hence apoB could be used as a single marker for screening dyslipidaemia in apparently healthy people.

关键词： Apolipoprotein B Dyslipidaemia High Density Lipoprotein Low Density Lipoprotein

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Biology of tooth replacement in amniotes

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International Journal of Oral Science 2013年第2期5卷 66-70页

作者： John A Whitlock Joy m Richman Department of Oral Health Sciences Faculty of DentistryLife Sciences InstituteUniversity of British Columbia

Tooth replacement is a common trait to most vertebrates, including mammals. mammals, however, have lost the capacity for continuous tooth renewal seen in most other vertebrates, and typically have only 1-2 generations of teeth. Here, we review the mechanisms of tooth replacement in reptiles and mammals, and discuss in detail the current and historical theories on control of timing and pattern of tooth replacement and development.

关键词： dental lamina growth factor signalling mammal epithelial stem cells diphyodonty polyphyodonty reptile successional lamina tooth replacement Zahnreihen, zone of inhibition

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Effect of TiO_(2) nanoparticles on the photocatalytic properties of pEO coatings on mg alloy

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Journal of magnesium and Alloys 2023年第2期11卷 735-752页

作者： D.V.mashtalyar I.m.Imshinetskiy K.V.Nadaraia A.S.Gnedenkov S.N.Suchkov D.p.Opra E.V.pustovalov A.Yu Ustinov S.L.Sinebryukhov S.V.Gnedenkov Institute of Chemistry Far Eastern BranchRussian Academy of SciencesVladivostok690022Russia Far Eastern Federal University Vladivostok690950Russia

A comprehensive study of the properties of coatings formed on a magnesium alloy by plasma electrolytic oxidation(pEO) using the electrolytes with nanosized particles of anatase(titanium dioxide) has been carried out. Formed coatings reduce corrosion current density 2.5-fold and increase hardness by 25% compared to a coating without particles. Confocal micro-Raman spectroscopy revealed the presence of anatase and rutile phases in the composition of pEO coating due to the incorporation of TiO2nanoparticles during plasma electrolytic treatment. The presence of titanium dioxide had a positive effect on the photocatalytic properties of coatings: the constant rate of the methyl orange and methyl blue decomposition is increased in 1.6 and 1.8-fold, respectively, compared to the coating formed in electrolyte without TiO_(2) particles.

关键词： plasma electrolytic oxidation Nanoparticles Titanium dioxide photocatalysis protective coatings

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small caliber overtube-assisted colonoscopy

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World Journal of Gastroenterology 2007年第44期13卷 5933-5937页

作者： Shai Friedland Roy m Soetikno Stanford University School of medicine and VA palo Alto Health Care System United States

AIm: To combine the benefits of a new thin flexible scope with elimination of excessive looping through the use of an overtube. mETHODS: Three separate retrospective series. Series 1: 25 consecutive male patients undergoing unsedated colonoscopy using the new device at a Veteran's hospital in the United States. Series 2: 75 male patients undergoing routine colonoscopy using an adult colonoscope, pediatric colonoscope, or the new device. Series 3: 35 patients who had incomplete colonoscopies using standard instruments. RESULTS: Complete colonoscopy was achieved in all 25 patients in the unsedated series with a median cecal intubation time of 6 min and a median maximal pain score of 3 on a 0-10 scale. In the 75 routine cases, there was significantly less pain with the thin scope compared to standard adult and pediatric colonoscopes. Of the 35 patients in the previously incomplete colonoscopy series, 33 were completed with the new system. CONCLUSION: small caliber overtube-assisted colonoscopy is less painful than colonoscopy with standard adult and pediatric colonoscopes. male patients could undergo unsedated colonoscopy with the new system with relatively little pain. The new device is also useful for most patients in whom colonoscopy cannot be completed with standard instruments.

关键词： Colonoscopy Endoscopy Colon Cancer Colon cancer screening

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Effects of rotation and magnetic field on the nonlinear peristaltic flow of a second-order fluid in an asymmetric channel through a porous medium

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Chinese physics B 2013年第7期22卷 303-313页

作者： A. m. Abd-Alla S. m. Abo-Dahab H. D. El-Shahrany Department of mathematics Faculty of ScienceTaif University Department of mathematics Faculty of Science Department of mathematics Faculty of ScienceSouth Valley University

In this paper, the effects of both rotation and magnetic field of the peristaltic transport of a second-order fluid through a porous medium in a channel are studied analytically and computed numerically. The material is represented by the constitutive equations for a second-order fluid. Closed-form solutions under the consideration of long wavelength and low Reynolds number is presented. The analytical expressions for the pressure gradient, pressure rise, friction force, stream function, shear stress, and velocity are obtained in the physical domain. The effects of the non-dimensional wave amplitude, porosity, magnetic field, rotation, and the dimensionless time-mean flow in the wave frame are analyzed theoretically and computed numerically. Numerical results are given and illustrated graphically in each case considered. Comparison was made with the results obtained in the presence and absence of rotation, magnetic field, and porosity. The results indicate that the effects of the non-dimensional wave amplitude, porosity, magnetic field, rotation, and the dimensionless time-mean flow are very pronounced in the phenomena.

关键词： peristaltic flow second-order fluid magnetic field porous medium

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Energy-momentum Distribution of Gravitational Waves

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Communications in Theoretical physics 2008年第9期50卷 664-668页

作者： m.Sharif Kanwal Nazir Department of mathematics University of the PunjabQuaid-e-Azain CampusLahore-54590Pakistan

This paper has been addressed to the well-known problem of energy in gravitational waves. We have investigated the energy of cylindrical gravitational waves in the context of General Relativity and teleparallel theory of gravity. For this purpose, the prescriptions of Einstein, Landau-Lifshitz, Bergmann-Thomson, and moeller are used in both the theories. It is shown that these energy-momentum complexes do not provide equivalent results in the two theories. However, these turn out to be constant for all the prescriptions except moeller in both the theories at large distances.

关键词： energy-momentum gravitational waves

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