Preparation and tribological properties of organically modified graphite oxide in liquid paraffin at ultra-low concentrations

RSC Advances ◽  
2015 ◽  
Vol 5 (110) ◽  
pp. 90525-90530 ◽  
Author(s):  
Lei Liu ◽  
Yongwei Chen ◽  
Peng Huang
Keyword(s):  
Tribological Properties ◽  
Graphite Oxide ◽  
Alkyl Chain ◽  
Liquid Paraffin ◽  
Friction Coefficients ◽  
Low Concentration ◽  
Low Concentrations ◽  
Organically Modified

Ultra-low concentration (0.008 wt%) of HDTMS or OTMS modified GO in liquid paraffin can reduce the friction coefficients (FC) of the mixtures by 34.0% and 15.5% respectively. HDTMS who possesses longer alkyl chain works better in decreasing FC.

Novel POSS based nanohybrids for improving tribological properties of liquid paraffin

RSC Advances ◽  
2016 ◽  
Vol 6 (97) ◽  
pp. 94876-94883 ◽  
Author(s):  
Lei Liu ◽  
Zhengquan Liu ◽  
Peng Huang
Keyword(s):  
Tribological Properties ◽  
Click Reaction ◽  
Liquid Paraffin ◽  
Low Concentration

POSS based nanohybrids were prepared via “thiol–ene click” reaction. As a novel additive, they are effective for improving the tribological properties at rather a low concentration when compared with pure solid or liquid lubricating additives.

scholarly journals Low Concentrations of Chlorhexidine Inhibit the Formation and Structural Integrity of Enzyme-Treated Multispecies Oral Biofilms

2021 ◽  
Vol 12 ◽  
Author(s):  
Kay Andrin Gränicher ◽  
Lamprini Karygianni ◽  
Thomas Attin ◽  
Thomas Thurnheer
Keyword(s):  
Structural Integrity ◽  
Fluorescent Dyes ◽  
Combined Treatment ◽  
Extracellular Proteins ◽  
Laser Scanning Microscopy ◽  
Extracellular Dna ◽  
Anaerobic Growth ◽  
Low Concentration ◽  
Low Concentrations ◽  
Dental Hard Tissues

The self-produced matrix of biofilms, consisting of extracellular polymeric substances, plays an important role in biofilm adhesion to surfaces and the structural integrity of biofilms. In dentistry, biofilms cause multiple diseases such as caries, periodontitis, and pulpitis. Disruption of these biofilms adhering to dental hard tissues may pose a major challenge since biofilms show higher tolerance to antimicrobials and antibiotics than planktonic cells. In this study, the effect of low concentrations of chlorhexidine (CHX) on enzyme-treated multispecies oral biofilm was investigated in an in vitro model. Six-species biofilms were enzymatically treated by anaerobic growth in a medium containing DNase I and proteinase K. Biofilms were exposed to a low concentration of CHX at defined time points. After 64h, biofilms were either harvested and quantified by cultural analyses or stained for confocal laser scanning microscopy (CLSM) analyses using either Live/Dead kit or different fluorescent dyes. A mixture of YoPro1 and SYTOX™ Green, Fluorescent Brightener 28 (Calcofluor), and SYPRO™ Ruby Protein Gel Stain was used to stain total DNA, exopolysaccharides, and extracellular proteins, respectively. Extracellular DNA (eDNA) was visualized via an indirect immunofluorescence assay (Mouse anti-DNA IgG, Goat anti-Mouse IgG, Streptavidin-Cy3). Overall, the total colony-forming units significantly decreased after combined treatment with a low concentration of CHX and enzymes compared to the group treated with CHX alone (p<0.001). These findings also apply to five species individually (Streptococcus mutans, Streptococcus oralis, Actinomyces oris, Veillonella dispar, and Candida albicans) occurring in the biofilms, with Fusobacterium nucleatum being the only exception. Furthermore, CLSM images showed less dense biofilms and a reduction in cell numbers after combined treatment compared to the group without enzymes. The combination of enzymes capable of disturbing the matrix integrity with antimicrobial agents thus appears to be a promising approach for biofilm disruption and killing.

Transepithelial movement of calcium in crustaceans

1993 ◽  
Vol 184 (1) ◽  
pp. 1-16 ◽  
Author(s):  
D. S. Neufeld ◽  
J. N. Cameron
Keyword(s):  
Active Transport ◽  
Calcium Concentration ◽  
Cellular Mechanism ◽  
The Body ◽  
High Rate ◽  
Calcium Flux ◽  
Moult Cycle ◽  
Electrochemical Gradient ◽  
Low Concentration ◽  
Low Concentrations

The regulation of calcium in most crustaceans is especially challenging owing to the highly mineralized cuticle that must be recalcified after each moult, a process that often occurs in environments with low concentrations of calcium. The gill and carapace epithelia separate the major calcium-containing compartments of the body and therefore see large changes in the rate of calcium flux through the moult cycle. Large changes in the ultrastructure of these cells do not, however, correlate well with the periods of calcium movement and probably reflect other physiological events. Despite the challenges to regulating calcium levels at various acclimation salinities and moult stages, the calcium concentration in the blood is maintained relatively constant. There is a rapid increase to a high rate of calcium flux across both the gill and carapace epithelium shortly after the moult; on an area-specific basis these fluxes are among the highest reported for calcium-transporting epithelia. When in water with a very low concentration of calcium, the electrochemical gradient for calcium is directed outwards and net influx must occur by active transport. Evidence suggests that changes in the electrochemical gradient, permeability and active transport are all important in the ability of crustaceans to take up calcium from water with a low concentration of this ion. Although an enzyme transporter is presumably involved in the active transport of calcium across epithelia, very little is known about the cellular mechanism of the transepithelial movement of calcium in crustaceans.

Low-friction mechanism of silicon carbide and cemented carbide in water

2020 ◽  
pp. 135065012092868
Author(s):  
Fei Guo ◽  
Fan Wu ◽  
Fangyong Wu ◽  
Yuming Wang
Keyword(s):  
Silicon Carbide ◽  
Tribological Properties ◽  
Rotation Speed ◽  
Hydrodynamic Lubrication ◽  
Cemented Carbide ◽  
Matched Pairs ◽  
Low Friction ◽  
Friction Mechanism ◽  
Friction Coefficients ◽  
Test Conditions

The tribological properties of self-mated silicon carbide, self-mated cemented carbide, and cemented carbide/silicon carbide under water lubrication were studied. The three matched pairs could achieve low-friction coefficients (0.01–0.03) under certain test conditions. Additionally, the dependence of the friction coefficients on the rotation speed and load were measured. By combining these results with the observed surface topography and wear measurements, it was determined that the three matched pairs were in the hydrodynamic lubrication. In addition, combined with experiments in ethylene glycol and PAO40, it was shown that the actual viscosity of the lubricant had a significant influence on the realization of low friction. Furthermore, matching materials had an influence on the tribological properties, which may be related to the surface wettability of the lubricant.

Inflammatory and Noninflammatory Synovial Fluids Exhibit New and Distinct Tribological Endotypes

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Elizabeth Feeney ◽  
Devis Galesso ◽  
Cynthia Secchieri ◽  
Francesca Oliviero ◽  
Roberta Ramonda ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Hyaluronic Acid ◽  
Synovial Fluid ◽  
Inflammatory Arthritis ◽  
Tribological Behavior ◽  
Friction Coefficients ◽  
Low Concentrations ◽  
Synovial Fluids ◽  
Erratic Behavior ◽  
Lubricating Properties

Abstract Inferior synovial lubrication is a hallmark of osteoarthritis (OA), and synovial fluid (SF) lubrication and composition are variable among OA patients. Hyaluronic acid (HA) viscosupplementation is a widely used therapy for improving SF viscoelasticity and lubrication, but it is unclear how the effectiveness of HA viscosupplements varies with arthritic endotype. The objective of this study was to investigate the effects of the HA viscosupplement, Hymovis®, on the lubricating properties of diseased SF from patients with noninflammatory OA and inflammatory arthritis (IA). The composition (cytokine, HA, and lubricin concentrations) of the SF was measured as well as the mechanical properties (rheology, tribology) of the SF alone and in a 1:1 mixture with the HA viscosupplement. Using rotational rheometry, no difference in SF viscosity was detected between disease types, and the addition of HA significantly increased all fluids' viscosities. In noninflammatory OA SF, friction coefficients followed a typical Stribeck pattern, and their magnitude was decreased by the addition of HA. While some of the IA SF also showed typical Stribeck behavior, a subset showed more erratic behavior with highly variable and larger friction coefficients. Interestingly, this aberrant behavior was not eliminated by the addition of HA, and it was associated with low concentrations of lubricin. Aberrant SF exhibited significantly lower effective viscosities compared to noninflammatory OA and IA SF with typical tribological behavior. Collectively, these results suggest that different endotypes of arthritis exist with respect to lubrication, which may impact the effectiveness of HA viscosupplements in reducing friction.

Quantitative analysis of low-concentration α-HMX based on terahertz spectroscopy

2020 ◽  
Vol 12 (47) ◽  
pp. 5684-5690
Author(s):  
Zhengmin Tang ◽  
Hu Deng ◽  
Quancheng Liu ◽  
Jin Guo ◽  
Liping Shang
Keyword(s):  
Quantitative Analysis ◽  
Terahertz Spectroscopy ◽  
Crystal Form ◽  
Low Concentration ◽  
Low Concentrations

Due to the instability of α type HMX at low concentrations, it belongs to the impurity crystal form.

Synthesis and Tribological Properties of S- and P-Free Borate Esters With Different Chain Lengths

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Guangbin Yang ◽  
Zhanming Zhang ◽  
Guihui Li ◽  
Jinfeng Zhang ◽  
Laigui Yu ◽  
...  
Keyword(s):  
Alkyl Chain ◽  
Liquid Paraffin ◽  
Alkyl Chain Length ◽  
Lubricating Oil ◽  
Oil Additives ◽  
Borate Esters ◽  
Lubricating Oil Additives ◽  
Steel Balls ◽  
Chain Lengths ◽  
Antiwear Ability

Three kinds of S- and P-free borate esters containing N with different alkyl chain lengths were prepared by using boric acid, ethanolamine, and alkyl-alcohol as the starting materials. The chemical structure of the products was analyzed by means of Fourier transformation infrared spectrometry, elemental analysis, and so on. The thermal stability of the products was evaluated by thermogravimetric analysis. The tribological properties of the synthesized borate esters as lubricating oil additives in liquid paraffin were evaluated using a four-ball friction and wear tester while the morphologies of the worn scars of the steel balls were observed using a scanning electron microscope. The chemical components on the worn surfaces of the steel balls were analyzed using an X-ray photoelectron spectroscopy. Results show that all the three kinds of synthetic borate esters as additives in liquid paraffin possess good antiwear performance and may be used as promising S- and P-free environmentally acceptable lubricating oil additives. Particularly, borate ester with short alkyl chain length at a low concentration in liquid paraffin was more effective in reducing wear, and the antiwear ability of the additives decreased with increasing alkyl chain length. The antiwear ability of the N-containing borate esters as additives in liquid paraffin might be closely related to the formation of hydrogen bonds via N with a high electronegativity and small atomic radius and the easy permeation of electron-deficient B on the rubbing steel surfaces.

Pressure-assisted synthesis of a polyaniline–graphite oxide (PANI–GO) hybrid and its friction reducing behavior in liquid paraffin (LP)

2018 ◽  
Vol 42 (2) ◽  
pp. 936-942 ◽  
Author(s):  
Lei Liu ◽  
Wei Zhou ◽  
Yongwei Chen ◽  
Songlong Jiao ◽  
Peng Huang
Keyword(s):  
Graphite Oxide ◽  
Liquid Paraffin ◽  
Optimum Concentration ◽  
Friction Property ◽  
Base Oil ◽  
Friction Reducing

PANI–GO hybrids were prepared via a pressure-assisted method, which can significantly enhance the anti-friction property of base oil at the optimum concentration of 0.012 wt%.

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