Effects of Andrade and Burgers rheologies on glacial isostatic adjustment modeling in Antarctica

Variations in ice mass deform the Earth and modify its gravity field,a process known as Glacial Isostatic Adjustment(GIA).GIA in Antarctica remains poorly constrained due to the cumulative effect of past and present ice-mass changes,the unknown history of the past ice-mass change,and the uncertainties on the mechanical properties of the Earth.This paper investigates the effect of using Andrade and Burgers viscoelastic rheologies,rather than the commonly used Maxwell rheology,to model GIA-induced deformation in Antarctica.The Love number and Green's function formalism are used to compute the radial surface displacements and the gravity changes induced by the past and present ice-mass changes.We consider an Earth model whose elastic properties and radial structure are averaged from the Preliminary Reference Earth Model and two viscosity profiles to account for the recently published results on the present ice-mass changes.Using the three rheological laws affects the temporal response of the Earth differently,leading to smaller discrepancies than those induced by the two viscosity structures.The differences are the largest between Maxwell and Burgers rheologies during the 100-1000 years following the beginning of the surface-mass change.Results show that using the Andrade and Burgers rheologies allows the Earth to respond on decennial to centennial time scales,up to 10 m more than Maxwell.Considering only the recent ice-mass changes,the deformation rates derived from Burgers and Andrade rheologies are several times larger than those estimated by Maxwell rheology.

Effect of Gum Arabic from Acacia senegal var. kerensis as an Improver on the Rheological Properties of Wheat Flour Dough

Dough improvers are substances with functional characteristics used in baking industry to enhance dough properties. Currently, the baking industry is faced with increasing demand for natural ingredients owing to increasing consumer awareness, thus contributing to the rising demand for natural hydrocolloids. Gum Arabic from Acacia senegal var. kerensis is a natural gum exhibiting excellent water binding and emulsification capacity. However, very little is reported on how it affects the rheological properties of wheat dough. The aim of this study was therefore, to determine the rheological properties of wheat dough with partial additions of gum Arabic as an improver. Six treatments were analyzed comprising of: flour-gum blends prepared by adding gum Arabic to wheat flour at different levels (1%, 2% and 3%), plain wheat flour (negative control), commercial bread flour and commercial chapati flour (positive controls). The rheological properties were determined using Brabender Farinograph, Brabender Extensograph and Brabender Viscograph. Results showed that addition of gum Arabic significantly (p chapati. These findings support the need to utilize gum Arabic from Acacia senegal var. kerensis as a dough improver.

Finite Deformation, Finite Strain Nonlinear Dynamics and Dynamic Bifurcation in TVE Solids with Rheology

This paper presents a mathematical model consisting of conservation and balance laws (CBL) of classical continuum mechanics (CCM) and ordered rate constitutive theories in Lagrangian description derived using entropy inequality and the representation theorem for thermoviscoelastic solids (TVES) with rheology. The CBL and the constitutive theories take into account finite deformation and finite strain deformation physics and are based on contravariant deviatoric second Piola-Kirchhoff stress tensor and its work conjugate covariant Green’s strain tensor and their material derivatives of up to order m and n respectively. All published works on nonlinear dynamics of TVES with rheology are mostly based on phenomenological mathematical models. In rare instances, some aspects of CBL are used but are incorrectly altered to obtain mass, stiffness and damping matrices using space-time decoupled approaches. In the work presented in this paper, we show that this is not possible using CBL of CCM for TVES with rheology. Thus, the mathematical models used currently in the published works are not the correct description of the physics of nonlinear dynamics of TVES with rheology. The mathematical model used in the present work is strictly based on the CBL of CCM and is thermodynamically and mathematically consistent and the space-time coupled finite element methodology used in this work is unconditionally stable and provides solutions with desired accuracy and is ideally suited for nonlinear dynamics of TVES with memory. The work in this paper is the first presentation of a mathematical model strictly based on CBL of CCM and the solution of the mathematical model is obtained using unconditionally stable space-time coupled computational methodology that provides control over the errors in the evolution. Both space-time coupled and space-time decoupled finite element formulations are considered for obtaining solutions of the IVPs described by the mathematical model and are presented in the paper. Factors or the physics influencing dynamic response and dynamic bifurcation for TVES with rheology are identified and are also demonstrated through model problem studies. A simple model problem consisting of a rod (1D) of TVES material with memory fixed at one end and subjected to harmonic excitation at the other end is considered to study nonlinear dynamics of TVES with rheology, frequency response as well as dynamic bifurcation phenomenon.

Unraveling the Rheology of Nanocellulose Aqueous Suspensions:A Comprehensive Study on Biomass-Derived Nanofibrillated Cellulose

The rheological properties of nanocellulose aqueous suspensions play a critical role in the development of nanocellulose-based bulk materials.High-crystalline,high-aspect ratio,and slender nanofibrillated cellulose(NFC)were extracted from four biomass resources.The cellulose nanofibrils and nanofibril bundles formed inter-connected networks in the NFC aqueous suspensions.The storage moduli of the suspensions with different concentrations were higher than their corresponding loss moduli.As the concentration increased,the storage and loss modulus of NFC dispersion increased.When the shear rate increased to a certain value,there were differences in the changing trend of the rheological behavior of NFC aqueous suspensions derived from different biomass resources and the suspensions with different solid concentrations.NFC dispersion’s storage and loss modulus increased when the temperature rose to nearly 80℃.We hope this study can deepen the understanding of the rheological properties of NFC colloids derived from different biomass resources.

Rheological Characterization of Systems with Plastic Flow Behavior

Model suspensions with plastic flow behavior were investigated rheologically.Shear stress and first normal stress difference were measured simultaneously with shear flow start-up experiments.After the shear deformation is stopped,the stress relaxation begins,residual shear stress can appear.The relative residual shear stressτRR is the ratio of the residual shear stress to the steady state shear stress.The relative residual shear stress is considered as a measure of the structure of the system.In the case ofτRR=0.98,we assume that an elastic to plastic deformation is occurred,which is the yield point.The system with 7.5%Aerosil 380 has achieved withτRR=0.95 in the first approximation the transition to plastic flow,this is the yield point for the system,with a yield stress of 23 Pa.This is the only one known system with yield point.The systems withτRR>0.30 andτRR<0.95 at the first point,have no transition from elastic to plastic flow,but the structure is strongly destroyed.Analogous to the above,the shear stress at this point will be called yield stress.One requirement is that the start-up experiment is determined with a very low shear rate¾0.00071/s or 0.000961/s.The associated normal stress to the yield stress is called normal yield stress.The dependence of the normal stress of the systems with Aerosil 380 on the shear stress reached,after a short increase/decrease in the values,the straight line of the normal stress/shear stress of the liquid phase M20000.A linear relationship between normal stress and shear stress was found in the systems with Bentone 27 in Araldite GY260.With a certain measured normal stress/shear stress point,you can draw a straight line with 45°in the double logarithmic plot¾a way to receive the normal stress/shear stress points.

Effects of stress conditions on rheological properties of granular soil in large triaxial rheology laboratory tests

In order to study the rheological properties of red stone granular soil,a series of rheological experiments were executed on large tri-axial rheological apparatus.Under 100,200 and 300 kPa confining stress conditions,the rheological tests were carried out.These experiment results showed that the stress conditions,especially the stress level were the critical influencing factors of the rheological deformation properties.Under the low stress level(S=0.1),the granular soil showed the elastic properties,and there was no obvious rheological deformation.Under the middle stress level(0.2<S≤0.6),creep curves showed the linear viscoelastic rheological properties.However,under the high stress level(S>0.8) creep curves showed the non-linear viscous plastic rheological properties.Especially,under the stress level of S=1.0,the accelerated rheological phase of creep curves occurred at early time with a trend of failure.The stress level had obvious effects on the final rheological deformation of the soil sample,and the final rheological deformation increments nonlinearly increased with stress level.The final rheological deformation increment and step was little under low stress level,while it became large under high stress level,which showed the nonlinearly rheological properties of the granular soil.The confining pressure also had direct effects on final rheological deformation,and the final rheological deformation linearly increased with confining pressure increments.

Structural Change of Wood Molecules and Chemorheological Behaviors during Chemical Treatment

It is very important to clarify the relationship of changes of molecular combinations in wood cell walls and the chemical rheological behavior during various chemical reagent treatments, for it would be helpful to develop new wood modification technologies and to enrich the theory of chemical rheology of wood. Based on previous investigations on the chemorheological properties of wood by chemical treatments and the applied methods in chemical rheology of wool fibers, this paper proposes the study of various additional reagents to wood saturated in water for long periods of time in order to investigate the chemical rheology of wood, which can provide information about the character of combinations between wood molecules and the structural changes of molecules and further put forward the idea of modifying wood in a decrystallized state.

Tribological and rheological performance of lithium grease with poly-a-olefin and alkyl-tetralin as base oils

A new category of lithium greases was synthesized by using poly-a-olefin(PAO8) and alkyl-tetralin as base oil, where the alkyl-tetralins were synthesized by the alkylation of tetralin and olefins. The influence of thickener concentration, alkyl-tetralin content and type of blend oils on the rheological and tribological performance of lithium grease was investigated. The microstructures of soap fibers were measured to reveal the structure-property correlations. The concentration of thickener and alkyl-tetralin content obviously affect the lubricating performance of lithium grease, while the molecular structure of alkyltetralin has no obvious impact on their properties. It was found that alkyl-tetralin could significantly enhance the thickening ability of PAO8 base oils, and decrease the amount of thickeners by 1.5%(mass).Lithium greases prepared using 20%(mass) alkyl-tetralin as co-base oil exhibited high colloidal stability,excellent rheological behaviors and tribological properties.

Rheological properties of a multiscale granular system during mixing of cemented paste backfill:A review

The technology of cemented paste backfill(CPB)is an effective method for green mining.In CPB,mixing is a vital process aiming to prepare a paste that meets the non-stratification,non-segregation,and non-bleeding requirements.As a multiscale granular system,homogenization is one of the challenges in the paste-mixing process.Due to the high shearing,high concentration,and multiscale characteristics,paste exhibits complex rheological properties in the mixing process.An overview of the mesomechanics and structural evolution is presented in this review.The effects of various influencing factors on the paste's rheological properties were investigated,and the rheological models of the paste were outlined from the macroscopic and mesoscopic levels.The results show that the mechanical effects and structural evolution are the fundamental factors affecting the rheological properties of the paste.Existing problems and future development trends are presented to change the practice where the CPB process comes first and the theory lags.

STUDY ON SCALP ELECTROACUPUNCTURE TREATMENT OF APOPLEXY AND ITS INFLUENCE ON HEMORHEOLOGY IN ISCHEMIC APOPLEXY PATIENTS

Objectives: To compare the therapeutic effect of scalp electroacupuncture with that of conventional body acupuncture for apoplexy (wind stroke) and to observe the influence of both acupuncture therapies on hemorheology of ischemic apoplexy.Methods: 183 patients, whose diseases are attributed to apoplexy according to the diagnostic criteria, are randomly divided into treatment group (93 cases) and control group (90 cases) and treated respectively with scalp electroacupuncture and conventional body acupuncture. 11 items of hemorheology of patients’ blood samples are tested with NXE-1 Viscometer which are taken in the early morning before and after treatment under fasting condition. Results: Both scalp electroacupuncture and conventional body acupuncture exert therapeutic effect for apoplexy, but the effect of scalp electroacupuncture is obviously better than that of conventional acupuncture (P< 0.05 ); both treatment group and control group are statistically significant in reducing plasma viscosity, high shear reduced viscosity, low shear reduced viscosity, erythrocyte sedimentation rate, hematocrit and fibrinogen, (P<0.01 and 0.05); while the treatment group is statistically significant in reducing whole blood viscosity, ratio of whole blood viscosity, erythrocyte index of rigidity and electrophoresis time of erythrocyte (P<0.01～ 0.05), but the control group is not significant statistically in influencing these indexes (P>0.05).

Effect of Oils on SBS Modified Asphalt:Rheological Characteristics and Oxidation Aging

This study focuses on the effect of oils on rheology and oxidation aging of Styrene-Butadiene-Styrene modified asphalt(SBSMA)in the long term,after reducing one low-temperature Performance Grade(PG)of SBSMA by incorporating oils.Two oils,including corn-based bio-oil and re-refined engine oil bottom(REOB),were selected to enhance the low-temperature performance of SBSMA.All samples were subjected to Rolling Thin Film Oven(RTFO)aging and 20-h as well as 40-h Pressure Aging Vessel(PAV20 and PAV40)aging,prior to multiple stress creep recovery(MSCR),frequency sweep and Flourier transform infrared spectroscopy(FTIR)scanning.A good high-temperature performance of oil/SBS modified asphalt blends was reflected in MSCR and PG results,meanwhile non-recoverable creep compliance(Jnr)and recovery(R)were found to share a highly correlated relationship during aging progress.In addition,Glover–Rowe(G–R)parameter and phase angle master curves suggest that the improvement of cracking property mainly came from the softening effect of oils.Adding oils into SBSMA was observed to increase oxidation kinetics,but the blends with oils still exhibited better anti-oxidation aging than the base binder,mainly due to the SBS addition.Bio-oil exhibited an effect of relieving age hardening susceptibility of SBSMA.

Physicochemical,rheological and antioxidant profiling of yogurt prepared from non-enzymatically and enzymatically hydrolyzed potato powder under refrigeration

Evidences show that the storage period greatly affects the quality of yogurt.In this study,three types of yogurt:control yogurt(CY),non-hydrolyzed potato powder yogurt(PPY)and enzymatically hydrolyzed potato powder yogurt(EHPPY)were prepared at 42℃ for 5 h and stored for 28 days at 4℃.The yogurts were evaluated for quality characteristics at different storage periods.Negligible differences in pH values,titratable acidities and viable counts were detected in all three types of yogurt during storage.However,compared to other yogurts,EHPPY exhibited desirable water holding capacity,throughout the storage period.Apart from this,sensory properties and antioxidant activities(2-diphenyl-1-picryl-hydrazyl(DPPH)free radical scavenging activity and ferric reducing antioxidant power(FRAP))of EHPPY were also significantly improved during the storage period.Furthermore,the storage(G’)and loss(G”)modulus of PPY,EHPPY were lower than CY at 4℃ while a hysteresis loop was shown by all yogurts at the temperature range of 4-50℃ indicating higher G’(elasticity)than G”(viscosity).Based on our findings,EHPP could be an important functional ingredient in improving the quality and storage stability of yogurt for its production at an industrial level.

ANTIHYPERLIPIDEMIC CAPSULES IN THE TREATMENT OF HYPERLIPIDEMIA AND ITS CLINICAL EFFECT ON HEMORRHEOLOGY AND AGGREGATION OF THROMBOCYTES

The authors treated 54 cases of hyperlipidemiawith the antihyperlipidemic capsules and the totalshort-term effective rate was 77.8%.The capsulesalso showed obvious effects in improving hemorrheo.logy,reducing aggregation of thrombocytes,andlowering the blood pressure.The authors believethey would be useful in the prevention and treat-ment of ischemic apoplexy and coronary disease.

Effects of Xuezhikang (Red Yeast Rice) on Blood lipids, Hemorheology and the Expression of P65 and Tissue Factor in Atherosclerotic Rats

Objective: To observe the effects of Xuezhikang (red yeast rice) on blood lipids, blood rheology, and expression of P65 and tissue factor, and to explore the anti-atherosclerosis effect and related mechanisms of Xuezhikang (red yeast rice). Methods: 32 Wistar rats were randomly divided into normal control group, Xuezhikang treatment group, lovastatin treatment group and atherosclerosis model group (8 in each group). Blood lipids, blood rheology, malondialdehyde (MDA), total antioxidant capacity (T-AOC), and expression of aortic tissue factor (TF) and P65 were measured in each group. Results:(1) Both Xuezhikang and lovastatin could reduce blood lipid levels, but there was no significant difference between the two groups;(2) Both Xuezhikang and lovastatin can improve the hemorheology of atherosclerotic rats, but the difference between the two groups is not significant;(3) Compared with lovastatin, Xuezhikang inhibited the expression of TF and P65 in aorta of rats with atherosclerosis;(4) Compared with lovastatin, the Xuezhikang group had lower MDA levels and higher T-AOC. Conclusion: Xuezhikang can improve blood lipid levels and hemorheology in rats with atherosclerosis. Compared with lovastatin, Xuezhikang has stronger effects on inhibiting oxidative stress and down-regulating the expression of tissue factor and P65.

Effect of general anesthesia on hemorrheology,hemodynamics and levels of blood E,NE and COS in patients undergoing gynecological surgery

Objective: To investigate the influence of general anesthesia on hemorheology, hemodynamics and blood E, NE and COS levels in patients undergoing gynecological surgery. Methods: A total of 87 cases of gynecologic laparoscopic surgery in our hospital from November 2015 to June 2017 were selected as subjects,all patients underwent general anesthesia for surgery, at the time of T1, T2, T3,the index of EDI, ηP, whole blood viscosity of blood rheology (high, middle and low shear), hemodynamic indexes of HR, BP, E, NE, SPO2 and serum COS level were measured. Results: (1) Compared with T1, 87 patients' HSV, MSV, LSV, ηP, EAI levels were significantly lower in T2 and T3, the difference was statistically significant, but there was no significant changes in the EDI three times;(2) Compared with T1, the levels of HR, SBP and DBP in 87 patients were significantly increased at T2 and T3, the difference was statistically significant, while the change of SPO2 levels at three moments was not statistically significant;(3) Compared with T1, the blood E, NE and COS levels in 87 patients increased significantly at T2 and T3, and the difference was statistically significant. Conclusion:Application of general anesthesia in gynecological surgery, can significantly reduce the blood viscosity of patients, but will increase the heart rate and blood pressure and blood E, NE and COS levels, therefore, during the operation, the patient's signs should be monitored comprehensively and closely.

Effects of low frequency electrical stimulation on monoamine neurotransmitters,cerebral blood flow and hemorheology in children with cerebral palsy

Objective: To investigate the effects of low frequency electrical stimulation on monoamine neurotransmitters, cerebral blood flow and hemorheology in children with cerebral palsy. Methods: A total of 83 children with cerebral palsy were divided into the control group (n=42) and the observation group (n=41) according to the random data table, patients in the control group were treated with routine rehabilitation treatment, on this basis;the children in the observation group were treated with low-frequency electric stimulation. Before and after the treatment, the levels of monoamine neurotransmitter [dopamine (DA) and 5-hydroxy tryptamine (5-HT) and norepinephrine (NE)], cerebral blood flow [the average blood flow velocity of anterior cerebral artery (ACA), middle cerebral artery (MCA) and posterior cerebral artery (PCA)] and blood rheology index [high/low shear whole blood viscosity, plasma viscosity and fibrinogen (FIB)] of two groups were compared. Results: Before treatment, there were no significant difference of the levels of DA, 5-HT, NE, the average blood flow velocity of ACA/MCA/PCA, high/low shear whole blood viscosity, plasma viscosity and FIB between the two groups. After treatment, two groups of DA, 5-HT and NE levels were significantly higher than those in the same group before treatment, and the observation group of DA, 5-HT and NE levels were significantly higher than those of the control group, the difference was statistically significant;The average blood flow rate of ACA/MCA/PCA in the observation group after treatment was significantly higher than those in the same group before treatment;After treatment, the levels of high shear/low shear blood viscosity, plasma viscosity and FIB of the two groups were significantly lower than those in the same group before treatment, and the levels of observation group after treatment were significantly lower than that in the control group, the difference was statistically significant. Conclusion: Low frequency electrical stimulation can effectively increase the level of monoamine neurotransmitter, improve the level of cerebral blood flow and hemorheology, has an important clinical value.

Effect of Dan seven soft capsule adjuvant therapy on serum inflammatory factors, coagulation function and blood rheology indexes in patients with acute hemorrhagic cerebrovascular disease

Objective: To investigate the effect of Dan seven soft capsule on the treatment of acute hemorrhagic cerebrovascular disease and the influence of serum inflammatory factors, coagulation function and blood rheology indexes. Methods: A total of 112 cases of patients with acute hemorrhagic cerebrovascular disease, according to the random data table were divided into the control group (n=57) and observation group (n=55), the patients in the control group received routine treatment combined with edaravone, on the basis of the treatment of the control group, the observation group was treated with Dan seven soft capsule. The serum levels of inflammatory factors, coagulation function and blood rheology indexes were compared between the two groups before and after treatment. Results: Before treatment, there were no significant difference in the inflammatory factors (hs-CRP, TNF-α and IL-6), blood coagulation function (FIB, PT and APTT) and hemorheology (high cut whole blood viscosity, low cut whole blood viscosity and plasma viscosity) levels between the control group and observation group. Compared with the levels of the same group before treatment, two groups of hs-CRP, TNF-α, IL-6, FIB, high cut whole blood viscosity, low cut whole blood viscosity and plasma viscosity level after treatment were significantly decreased, and levels in the observation group were significantly lower than those in the control group;Compared with the group before treatment, the levels of PT and APTT in the two groups were significantly increased, and the observation group was significantly higher than the control group. Conclusion: Dan seven soft capsule in the treatment of acute hemorrhagic cerebrovascular disease can effectively reduce the level of serum inflammatory factors, improve coagulation function and blood rheology index, it has an important clinical value.

Rheology of a Viscous-Plastic Liquid in a Porous Medium

The hydrodynamics of the capillary flow of a viscous-plastic liquid in cylindrical rectilinear pores is considered, as a result of which the structural velocity distribution over the pore cross section is obtained. Analytical solutions are proposed for the equations of hydraulic diffusion and nonlinear filtration for a non-Newtonian fluid in a cylindrical porous medium. It is noted that when a non-Newtonian fluid flows in a porous medium, the filtration equations take a nonlinear form due to the effective viscosity, shear, and yield stresses taken into account in its structure. The proposed solutions make it possible to evaluate the state of the porous medium and its main parameters (permeability, hydraulic diffusion, and effective viscosity coefficients). The obtained solutions are compared with existing experimental data for non-Newtonian oils.

固井水泥浆用两性离子型聚羧酸分散剂的合成及性能评价

现有缩聚物类分散剂因技术和环保问题,其生产和使用受到限制。聚羧酸(PCE)高性能减水剂,绿色环保,分散性能优异,在混凝土工业中广泛使用,但常规PCE应用于固井水泥浆存在强缓凝问题。以甲基烯丙基聚乙二醇醚、丙烯酸和甲基丙烯酰氧乙基三甲基氯化铵为原料,分别合成了常规阴离子型聚羧酸(CPC)和两性离子型聚羧酸(DPC)分散剂,并对其结构进行了表征,同时研究了CPC和DPC对水泥浆流动度、流变性能、稠化时间和抗压强度的影响和作用机理。结果表明:CPC和DPC均有良好的分散性能,但在稠化时间和抗压强度性能上DPC远超CPC。CPC存在很强的缓凝作用,导致稠化时间大幅延长,水泥石早期强度下降。引入季铵阳离子合成的DPC,缓凝作用微弱,对稠化时间影响不大,有利于水泥石早期强度提高。

井地过渡带对聚合物驱油剂性能影响研究

利用井地过渡带剪切模拟实验装置,以疏水缔合聚合物AP-P4为研究对象,研究不同吸水强度条件下,剪切后聚合物溶液的表观黏度、流变性、阻力和残余阻力系数、微观结构以及水动力学半径的变化情况。结果表明,经井地过渡带剪切后,随着吸水强度的增大,聚合物AP-P4溶液的黏度损失率高达61.4%,建立阻力系数和残余阻力系数的能力降低40.0%以上,但其建立残余阻力系数能力的降低幅度要比建立阻力系数能力的降低幅度小。聚合物溶液的储能模量和损耗模量降低,微观结构被破坏的越严重,水动力学半径越小。