In present work, the abrasive-free jet polishing (AFJP) of bulk single-crystal KDP was first fulfilled, when using a newly-designed low-viscosity microemulsion as the AFJP fluid. The novel AFJP fluid ...shows a typical water-in-oil structure, in which the water cores uniformly distribute in the BmimPF6 IL, with a particle size of about 20-25 nm. What's more, the AFJP fluid is a controllable and selective non-abrasive jet fluid that the shape of the removal function is regular and smooth, presenting a similar Gaussian function, meanwhile, the dispersion coefficient of the removal rate is only 1.9%. Finally, the surface quality of the bulk single-crystal KDP is further improved by AFJP, meanwhile, the subsurface damage is first obviously mitigated.
Cilia/flagella are whip-like, cellular appendages, widely conserved across the eukaryotes, that move a single cell through fluid, or move fluid across epithelial tissue. The flagella in the ...biflagellate alga Chlamydomonas reinhardtii are homologous to those found in humans, for example in sperm cells, and therefore, studying flagella in the algae can shed light on human disease. In this thesis, I develop a new quantitative framework for characterising flagellar activity, beginning by tracking the waveforms of C. reinhardtii flagella, and using the tracked waveforms to estimate various parameters that are relevant to flagellar beating, including frequency, amplitude, synchrony, hydrodynamic and elastic moments, curvature propagation and beat variability. These parameters have been estimated for wild-type and outer-dynein mutant flagella, as well as those immersed in a higher-viscosity medium, and for actively regrowing flagella. The results show that flagella of the mutant strain propagate weaker beats than in the wild type, while those in a raised viscosity are weaker still. For example, in a novel measure of the strength of curvature propagation, the mutant is 38% weaker, and the high-viscosity flagella 80% weaker, than the wild type. Additionally, the dynein mutant shows increased variability of the centre of force, but not the beat frequency. These results could aid with diagnosis of diseases caused by defective cilia, such as primary ciliary dyskinesia, as well as gaining further insight into the mechanisms of diseases caused by excessively viscous mucus, such as cystic fibrosis. Regrowing flagella were found to gradually recover their full-length parameters, but this increase in length was accompanied by an increase in the noise with which they beat, and a temporary aberration in the other flagellum.
Comb and bottlebrush polymers present a wide range of rheological and mechanical properties that can be controlled through their molecular characteristics, such as the backbone and side chain lengths ...as well as the number of branches per molecule or the grafting density. This review investigates the impact of these characteristics specifically on the zero shear viscosity, strain hardening behavior, and plateau shear modulus. It is shown that for a comb polymer with an entangled backbone and entangled side chains, a maximum in the strain hardening factor and minimum in the zero shear viscosity η0 can be achieved through selection of an optimum number of branches q. Bottlebrush polymers with flexible filaments and extremely low plateau shear moduli relative to linear polymers open the door for a new class of solvent‐free supersoft elastomers, where their network modulus can be controlled through both the degree of polymerization between crosslinks, nx, and the length of the side chains, nsc, with GBB0≈ρkTnx−1(nsc+1)−1.
Comb and bottlebrush polymers exhibit unusual rheological properties compared to their linear analogs due to side‐chain crowding. Investigation of the melt rheology of model branched polymers with controlled grafting density, side chain, and backbone lengths allows correlation of macroscopic flow properties such as zero shear viscosity, plateau modulus, and strain‐hardening behavior to conformational regimes by means of scaling analysis and tube theory.
Temperature‐dependent viscosity is critical to decipher two profound questions in condensed matter physics, namely the glass transition and the relaxation of amorphous solids. However, direct ...measurement of viscosity over a large temperature range is extremely difficult. Here, using classical molecular dynamics (MD) simulations, we report a novel method to calculate the equilibrium viscosity of supercooled liquid both above and below the glass transition temperature (Tg) and to estimate the nonequilibrium viscosity of glass down to room temperature. Based on the shoving model, we derived an analytical formula showing that the shear viscosity in logarithmic scale changes linearly with the shear‐induced variation in shear modulus or potential energy of the glass‐forming system. The shear viscosity as a function of steady‐state potential energy of liquid under different shear strain rates can be directly calculated in MD simulations; together with its equilibrium potential energy, one can extrapolate the zero‐strain‐rate equilibrium viscosity. We verified the proposed model by reliably calculating equilibrium viscosity near Tg of four glass‐forming systems (Kob–Andersen system, silica, Cu45.5Zr45.5Al9, and silicon) with different fragilities. Furthermore, our model can estimate the nonequilibrium viscosity of glass below Tg; the upper‐bound nonequilibrium viscosity of amorphous silica and silicon at room temperature are calculated to be ~1032 and 1025 Pa·s, respectively.
Equilibrium viscosity calculated in this work for silica and Cu45.5Zr45.5Al9 in comparison with experiments in the Angell's plot.
•Crystallisation effects on the slag phase assemblage/slag viscosity are reviewed.•Newtonian/non-Newtonian flow transitions in crystallising slags are discussed.•Discrepancy in Tcv definitions is ...demonstrated; Tcv physical meaning is discussed.•An alternative and more plausible definition of Tcv is suggested and illustrated.•The differences between the characteristic temperatures of slags are demonstrated.
The crystallisation in coal ash slags plays a critical role in coal combustion and gasification. The stable operation of a boiler or entrained-flow gasifier is vitally dependent on the easy, continuous removal of combustion by-products in the form of coal ash slags. Of the factors that govern the flow of a coal ash slag in a reactor, slag viscosity is the most important. Crystallisation affects overall slag behaviour and properties, but its most pronounced effect is on slag flow characteristics. It increases slag viscosity, causes Newtonian slag flow to transition to non-Newtonian, and yields the temperature of critical viscosity. In this paper, we systematically review and analyse the complex effect of crystallisation on these three factors.
Flow harmonics (vn) of the Fourier expansion for the azimuthal distributions of hadrons are commonly employed to quantify the azimuthal anisotropy of particle production relative to the collision ...symmetry planes. While lower order Fourier coefficients (v2 and v3) are more directly related to the corresponding eccentricities of the initial state, the higher-order flow harmonics (vn>3) can be induced by a mode-coupled response to the lower-order anisotropies, in addition to a linear response to the same-order anisotropies. These higher-order flow harmonics and their linear and mode-coupled contributions can be used to more precisely constrain the initial conditions and the transport properties of the medium in theoretical models. The multiparticle azimuthal cumulant method is used to measure the linear and mode-coupled contributions in the higher-order anisotropic flow, the mode-coupled response coefficients, and the correlations of the event plane angles for charged particles as functions of centrality and transverse momentum in Au+Au collisions at nucleon-nucleon center-of-mass energy sNN= 200 GeV. The results are compared to similar LHC measurements as well as to several viscous hydrodynamic calculations with varying initial conditions.
The relation between the specific shear viscosity η/s and the dimensionless jet quenching parameter ... in perturbative QCD is explored at next-to-leading order in the coupling constant. It is shown ...that the relation changes little, although both transport coefficients independently are subject to large modifications at the next-to-leading order level. This finding confirms that the relationship is robust.(ProQuest: … denotes formula omitted.)
The development of high-performance lubricants to decrease engine friction and then reduce fuel consumption remains a major challenge for oil manufacturers. Viscosity index improvers (VIIs) are ...additives used for decades to reduce the dependency of the lubricant's viscosity on temperature to maintain an acceptable lubrication in harsh conditions. Distinction between VIIs and thickeners in realistic engine conditions is of primary interest for oil manufacturers in order to optimize the formulation process. In this context, rheological studies can provide clear insights into the actual effect of such polymeric additives. The behavior of a simplified automotive lubricant is investigated at different temperatures and high pressure and high shear stress and modeling of the properties is proposed. Various polymers of different molecular weights and conformations were mixed in a hydrocracked mineral base oil. The viscosity variations with temperature, pressure, and shear stress, obtained from specific rheometers, were then represented by different models, namely, a Vogel-Fulcher-Tamman expression, a modified Williams-Landel-Ferry correlation, and a Carreau-Yasuda equation. Different rheological responses were observed and allowed the distinction between VIIs and thickeners under different temperature and pressure conditions. The hydrodynamic radii analysis provided an explanation of the rheological responses but also highlighted the limits of the Carreau-Yasuda equation when applied to VIIs. Therefore, the Zhang expression, based on the Maxwell model and applied here to low viscoelastic solutions, is proposed as an appropriate alternative.
For a variety of viscosity-related diseases, studying blood viscosity may be an ever so direct, simple, non-invasive as well as effective pre-diagnostic method. At present, the main cause for the ...insufficiently thorough studies on blood viscosity is the lack of tools that can not only self-calibrate but also shield the interference of bio-auto fluorescence from blood. Herein, we have judiciously designed and synthesized a new fluorescent probe Nile-TPE to tackle the above problem. This TBET structure based fluorescent probe possess numerous merits including near-infrared (NIR) emission, ratiometric response, lipid droplets positioning, wide emission peak spacing, etc. Besides the viscosity ratiometric imaging in vitro, probe Nile-TPE also realizes the ratiometric imaging viscosity in mice and detecting blood viscosity in peritonitis mice and folliculitis mice for the first time. And, importantly, this effective method requires only 10 μL of blood. Therefore, probe Nile-TPE furnishes a more accurate tool for non-invasive diagnosis of viscosity-related diseases.
Constructing a new NIR fluorescent probe for ratiometric imaging viscosity in the mice and detecting blood viscosity in the folliculitis mice and peritonitis mice Display omitted
•We have judiciously designed the first chemosensor for detecting blood viscosity of mice with viscosity-related diseases.•Probe Nile-TPE is a TBET based ratiometric fluorescent probe with near infrared emission.•Nile-TPE possess virtues including ratiometric response, good LDs targeting ability, wide emission peak spacing, etc.•Probe Nile-TPE enables the non-invasive measurement of blood viscosity while shielding the auto-fluorescence interference.•The blood viscosity of mice with folliculitis and peritonitis was 1.51 and 1.21-1.27 times higher than normal mice.
•Thermal conductivity and viscosity models of nanofluids were reviewed.•Metallic oxides nanofluids (Al2O3, CuO, SiO2 and ZnO) were considered.•Various shapes of nanoparticles were selected.•Thermal ...conductivity increased as temperature and concentration increased.•Nanoparticles shape has sufficient impact on thermophysical properties of nanofluids.
For over ten years, investigators focused on determining and modelling the effective thermal conductivity and viscosity of nanofluids. Lately, many theoretical and experimental investigations on convective heat transfer have been performed on the augmentation of heat transfer by utilizing suspensions of nanometer-sized solid particle materials (metallic or nonmetallic) in base fluids. The main purpose of this work is to determine the thermal conductivity and viscosity of various types of metallic oxides (Al2O3, CuO, SiO2 and ZnO) for nanoparticle concentrations of 1–5 vol% at temperatures of 300–320 K and nanoparticle shapes (blades, platelets, cylindrical, bricks, and spherical). The results illustrate that the effective thermal conductivity and thermal conductivity ratio of metallic oxide nanofluids increase with temperature and nanoparticles volume fraction but decreases nanoparticle size intensifies. Besides that, the results of effective viscosity and viscosity ratio obtained indicate a considerable rise with the increase of nanoparticles concentration. Thus, optimum nanoparticle concentration is essential to be determined in forming nanofluids that can enhance thermal systems performance. Finally, it is found that nanoparticles shape has great impact on the thermophysical properties of nanofluids.
PDF
