Low Shear Viscosity Research Articles

Camphene/polystyrene solutions: A rheological approach for material processing industry

ABSTRACTRheological properties of polymer–camphene solutions are very relevant as they affect their stability, and they have many implications in operation costs. This work elucidates the rheological properties of polystyrene (PS–camphene) solutions with industrial applications. Unfortunately, the assessment of the very low shear viscosities of camphene‐based materials (below 0.005 Pa s) is still a challenge with commercial rheometers. Flow curves, stress growth tests, and small amplitude oscillatory shear (SAOS) measurements were carried out as a function of PS concentration (0, 2.5, 5.0, 10, and 20 wt % PS) to understand the rheological behavior of these systems. Results indicate that liquid camphene has a shear‐thinning behavior (flow index = 0.99) when the increase of polymer concentration involves changes in the structure of these systems (flow index = 0.10 for 20 wt % PS). An increase in PS concentration leads to a forwarding in the shear‐thinning zone, and the Newtonian region (from ∼1 s−1, for 0 wt % PS, to 10−3 s−1 for 20 wt % PS). Eventually, these results evidence the high dependence of η∞ on PS concentration (from ∼1.16 ± 0.01 Pa s, for 0 wt % PS, to 631.5 ± 0.2 Pa s for 20 wt % PS). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47953.

Characteristics of Aerogels Manufacturing Using Wastepaper

In order to evaluate the possibility of producing aerogels using waste paper, white ledger and KOCC (Korea old corrugated container) were fibrillated to produce aerogels and their characteristics were compared with those of hardwood bleached kraft pulp. Grinding was performed at 5, 10, 15 and 20 times, and the concentration of fibrillated fiber was adjusted to 0.5, 1.0 and 1.5% in order to investigate the effect of fibrillation degree and the fibrillated fiber concentration. As the grinding progressed, the average fiber length decreased. In the case of white ledger, the increase of low shear viscosity was delayed. In the case of KOCC, little change was observed, which is closely related to the fibrillation characteristics of the fiber. The degree of polymerization of hardwood bleached kraft pulp and white ledger decreased as the number of grinding times increased. However, KOCC showed no significant change. As the grinding number and fibrillated fiber concentration increased, the specific surface area of the aerogels increased, but the average pore size decreased. These properties were closely related to the fibrillation characteristics of the fibers. As the pore size of the aerogels decreased, the absorption of water and oil decreased. The absorption of water by hydrophobic treatment of aerogels was significantly decreased, but the absorption of oil was improved for white ledger and KOCC.

A reverse lyotropic liquid crystal formed by cetylpyridiniumchloride in cyclohexane with the assistance of aromatic counterions

The self-assembly of the cationic surfactant cetylpyridiniumchloride (CPC) in cyclohexane was studied using polarizing-microscopy (POM), small angle X-ray scattering (SAXS), and rheology measurements. Homogeneous solutions of CPC/aromatic salts were produced using aromatic salts, specifically, NaBzs, NaNphs, or NaSal. The majority of the samples showed highly viscous gel-like appearances. SAXS measurements together with POM observations indicate hexagonal liquid crystals in both the CPC/NaNphs and CPC/NaSal, while multiple types of aggregates were shown to co-exist in the CPC/NaBzs. These were attributed to the interactions of aromatic counterions with the pyridinium head-group of CPC, resulting in increased size of the CPC head to different extents depending on the aromatic counterions. The formation of core-shell aggregates consequently caused further packing into liquid crystals. The specific role of NaSal that carried an ortho-hydroxyl in its benzene ring is discussed, and the mechanism of trace water molecules bridging neighboring NaSal molecules was revealed according to Fourier transform infrared (FT-IR) measurements. The samples had high viscoelasticity, for example, the steady-state low-shear viscosity at a shear rate of 0.001, ηL, of the samples at W0 = 32 was 3.3 × 105, 2.0 × 104, and 6.8 × 102 Pa·s for CPC/NaBzs, CPC/NaNphs, and CPC/NaSal, respectively, at 25 °C. The corresponding elastic plateau moduli, G′P, were 1.9 × 103, 1.1 × 103, and 1.1 × 102 Pa, respectively. The temperature effect was examined for samples at W0 = 32, which were found to retain high viscosity at higher temperatures, for example, the relative viscosity to solvent cyclohexane, ηr, reached 107 and 105 for CPC/NaBzs and CPC/NaNphs, respectively, at 70 °C.

Effects of Premixing Wood Flour with Compatibilizer with Different Characteristics on the Physical and Mechanical Properties of Wood/Plastic Composites

Abstract The addition of maleic anhydride (MA)-modified polypropylene (MAPP) as a compatibilizer increases mechanical and physical properties of wood/plastic composites (WPCs). It is thought that MA graft ratio (Gr), molecular weight (weight-average molecular weight [Mw]), and mixing methods of MAPP affect physical and mechanical properties of WPCs. However, evaluation, especially for mixing order, is not enough. The objective of this study was to investigate the effect of Gr and Mw of MAPP and its mixing methods on the mechanical and physical properties of WPCs. Two types of mixing methods were used: mixing the MAPP with the filler using a Henschel mixer before kneading with PP (premixing method) and mixing all of the materials at one time (one-step mixing method). The WPCs made with the premixing method had lower shear viscosity and higher flexural modulus than those made with the one-step mixing method. The particle size, moisture content, and surface morphology of fillers are thought to be more important in determining the shear viscosity of WPCs than the MAPP itself. The highest tensile, impact, and flexural strengths of WPCs were obtained in the WPC with premixing with low-Gr and high-Mw MAPP. It may be due to the effective reaction of the wood flour with MAPP and higher entanglement between the MAPP and PP. These results suggest that the premixing method could improve productivity and mechanical properties of WPCs.

In Vitro Study on the Dynamics of Blood Flow Impelled by an Alternating Current Magnetohydrodynamic Blood Pump.

Artificial hearts are effective devices to treat heart failure in clinical practice and can be divided into two categories: artificial hearts and ventricular assist devices. The goal of this work was to investigate the fluidity and biological changes of in vitro sheep blood using a novel alternating current (AC) magnetohydrodynamic blood pump (central magnetic intensity: 0.9 T, alternating current frequency of the electric motor: 0-80 Hz). Blood samples were collected from five sheep and were divided into two groups: the control group (no exposure to an external magnetic field) and the exposed group (3 h of exposure to an alternating magnetic field). The blood cell counts, changes in blood viscosity, and ultrastructural changes of the blood cells under transmission electron microscopy were investigated. This study demonstrated several findings: (i) Continuous sheep blood flow can be achieved; (ii) The blood cell counts remained unchanged after 3 h of exposure to an alternating magnetic field; (iii) Compared with the control group, the high- and low-shear viscosities of the whole blood from the sheep significantly decreased after 3 h of exposure to an alternating magnetic field (P < 0.05 and P < 0.01, respectively). Plasma viscosity was significantly reduced after exposure to high-intensity alternating magnetic fields (P < 0.001); (iv) The cytoplasm of blood cells (especially erythrocytes) became lighter in color in the exposure group compared to the control group, and "beads-on-string" aggregations of black particles appeared. This work provides detailed and reliable scientific research data for the development of this type of blood pump, which may serve as a transition to the clinical artificial heart.

Salvianolate injection in the treatment of acute cerebral infarction: A systematic review and a meta-analysis.

To evaluate the effectiveness and safety of Salvianolate injection (SI) in the treatment of acute cerebral infarction (ACI).We electronically searched databases including PubMed, The Cochrane Library, EMBASE, Chinese Biomedical Literature Database, Chinese National Knowledge Infrastructure, and WanFang Data to collect randomized controlled trials (RCTs) focused on SI treating ACI up to August 2017. Two reviewers independently screened literatures, extracted data, and assessed the risk of bias of included studies. Then, meta-analysis was performed using RevMan 5.3 software.A total of 39 RCTs involving 4516 patients were included. The results of meta-analysis showed that compared with the Western medicine (WM) therapies group [experimental group (EG)], the total effective rate of SI + WM [control group (CG)] was higher (relative risk = 1.29, 95% CI: 1.24–1.35, P < .00001) in 21 RCTs; SI could improve movement function evaluation scores, including National Institute of Health Stroke Scale, Barthel Index, activities of daily living (P < .00001). There was no significant difference in modified Rankin Scale scores between the 2 groups (P = .008) EG was better than CG in improving Montreal Cognitive Assessment scores (P = .001) and Mini-Mental State Examination scores (P < .00001). SI could improved not only the hemorheology indexes, including plasma viscosity, whole blood high-shear viscosity, whole blood low-shear viscosity, fibrinogen (P < .00001), but also high-sensitivity C-reactive protein and C-reactive protein. EG could achieve a better effect on improving the neural deficit scores (P < .00001). There was no significant difference about adverse drug reactions/adverse drug events between the EG and CG (P = .73).Salvianolate can promote recovery of the motor and cognitive function of patients with ACI. However, due to the limited quality and quantity of included studies, more high-quality studies are needed to verify the above conclusion.

The Viscosity of Polyalphaolefins Mixtures at High Pressure and Stress

Understanding the pressure and shear dependence of viscosity is essential to an understanding of the mechanisms of film forming and friction in concentrated contacts. The blending of different molecular mass polyalphaolefins (PAOs) may permit the formulator to arrive at a desired combination of film thickness and friction. The viscosities of PAO base oils and their blends were measured versus temperature, pressure, and shear stress to 1 GPa in pressure. The Grunberg–Nissan mixing rule, with effective mole fractions, provides an excellent mixing rule for the temperature and pressure-dependent low-shear viscosity. This work provides the first look at a possible mixing rule for the non-Newtonian response of mixtures of base oils.

On the Reological Properties of Human Blood

This short communication will establish a reasonably robust procedure to evaluate each of the parameters required in non-Newtonian constitutive relationships for human blood, viz. Cross, Carrau-Yasuda and modifications to Oswald-de Waele and Sisko fluids. For each of the rheological models presented herein the free parameter set to is optimally fitted to a compilation of digitized experimental data evident in the literature. It is shown that for three of the models to conserve structural identification the so-called low shear viscosity term should be set. The method presented herein is shown to minimize the square of the errors between the four suggested constitute relationships and empirical data. It is shown that, for the data set investigated here, parameters which had previously been assumed to be fluid properties exhibit different values depending on the selection of the constitutive relationship.

Systematic review on efficacy and safety of Danshen Chuanxiongqin Injection in treatment of acute cerebral infarction

To systemically evaluate the therapeutic efficacy and safety of Danshen Chuanxiongqin Injection in treatment of acute cerebral infarction and provide the reference of evidence-based medicine for its clinical safety and effective drug use. Databases including CNKI, WanFang Data, SinoMed, the Cochrane Library, EMbase and PubMed were searched from inception to April 2018 to collect the randomized controlled trials (RCTs) on Danshen Chuanxiongqin Injection in the treatment of acute cerebral infarction. The quality of all included studies was evaluated by two independent reviewers following the cochrane systematic review method and using Revman5.3 software and State13.0 for Meta-analysis. A total of 30 RCTs involving 3 233 patients with acute cerebral infarction were included in the study after literature quality evaluation. Meta-analysis showed that as compared with the control group of conventional western medicine alone, Danshen Chuanxiongqin Injection combined with conventional western medicine can achieve better efficacy in treatment of acute cerebral infarction, increase the clinical total effective rate (RR=1.22, 95% CI [1.18, 1.27], P<0.000 01) and activities of daily living (MD=9.42, 95% CI [8.12, 10.72], P<0.000 01), and improve the degree of neurological impairment (MD=-3.99, 95% CI [-4.89, -3.07], P<0.000 01). Furthermore, the result showed that Danshen Chuanxiongqin Injection in the treatment of acute cerebral infarction can significantly decrease the whole blood high-shear viscosity, whole blood low-shear viscosity, plasma viscosity, fibrinogen level and other hemorheological indexes (P<0.01). This Meta-analysis demonstrated that Danshen Chuan xiongqin injection in the treatment of acute cerebral infarction is safe and effective, but lacks the large multicenter clinical randomized trials to support the treatment outcome.

Drop breakup dynamics of dilute polymer solutions: Effect of molecular weight, concentration, and viscosity

The large extensional viscosity of dilute polymer solutions has been shown to dramatically delay the breakup of jets into drops. For low shear viscosity solutions, the jet breakup is initially governed by a balance of inertial and capillary stresses before transitioning to a balance of viscoelastic and capillary stresses at later times. This transition occurs at a critical time when the radius decay dynamics shift from a 2/3 power law to an exponential decay as the increasing deformation rate imposed on the fluid filament results in large molecular deformations and rapid crossover into the elasto-capillary regime. By experimental fits of the elasto-capillary thinning diameter data, a relaxation time of less than 100 μs has been successfully measured. In this paper, we show that, with a better understanding of the transition from the inertia-capillary to the elasto-capillary breakup regime, relaxation times close to 10 μs can be measured with the relaxation time resolution limited only by the frame rate and spatial resolution of the high speed camera. In this paper, the dynamics of drop formation and pinch-off are presented using dripping onto substrate capillary breakup extensional rheometry (CaBER-DoS) for a series of dilute solutions of polyethylene oxide (PEO) in water and in a viscosified water and glycerin mixture. Four different molecular weights between 100 k and 1 M g/mol were studied with varying solution viscosities between 1 and 22 mPa s and at concentrations between 0.004 and 0.5 times the overlap concentration, c*. The dependence of the relaxation time and extensional viscosity on these varying parameters was studied and compared to the predictions of dilute solution theory while simultaneously searching for the lower limit in solution elasticity that can be detected. For PEO in water, this limit was found to be a fluid with a relaxation time of roughly 20 μs. These results confirm that CaBER-DoS can be a powerful technique characterizing the rheology of a notoriously difficult material to quantify, namely, low viscosity inkjet printer inks.

Effects of sleep deprivation induced blood stasis syndrome on platelet activation in rats

Blood stasis syndrome is the pre-state of thrombotic disease. The model of blood stasis syndrome in rats was induced by sleep deprivation to study on effects of blood stasis syndrome on platelet activation. The weight, the color of tongue and hemorheology for the blood stasis syndrome of Chinese medicine were measured after modeling. The release of platelet granules and platelet activation factors in plasma were detected by ELISA kit related indicators to provide experimental basis for platelet function evaluation and related drug effects in syndrome research. The results showed that the weight of the model group rats was significantly lower than that of the normal group (P<0.01). The tongue showed a dark purple blood stasis pattern, and the R, G and B values of the tongue surface in model group were significantly lower than those of the normal group (P<0.01). The hemorheological parameters including high shear, middle shear and low shear viscosity in whole blood were significantly higher than those in the normal group (P<0.01). But plasma viscosity did not change significantly. The release levels of platelet α particles (GMP-140, β-TG, PF4) and dense particles (ADP, 5-HT) were significantly higher than those in the normal group (P<0.01). The levels of TXB₂ and 6-keto-PGF₁α in plasma were significantly higher than those in the normal group (P<0.01). The ratios of TXB₂ and 6-keto-PGF₂α were also significantly higher than those in the normal group (P<0.01). The levels of PAF in plasma in model group were significantly higher than those in the normal group (P<0.01). It was concluded that platelet functions could be changed induced by sleep deprivationin rats with blood stasis syndrome, and there might be inflammation and endothelial cell dysfunction.

Unilateral digital arterial ligation combined with low molecular weight heparins in severed finger without venous anastomosis.

Curative effect of unilateral digital arterial ligation combined with low molecular weight heparins in the treatment of severed finger without venous anastomosis and its influence on venous crisis was studied. A total of 80 patients with distal severed finger treated in Wuxi No. 9 People's Hospital from May 2014 to July 2016 were selected into the study. According to the random number table, they were divided into the control group (n=40) and the research group (n=40). The patients in control group were treated with unilateral digital arterial ligation, while the patients in research group were treated with unilateral digital arterial ligation combined with low molecular weight heparin. The wound healing time after operation, hospitalization time, hemorheology detection results, survival rate and necrosis rate of replanted finger, incidence rate of venous crisis and recovery effect of replanted finger were compared between the two groups. After operation, the wound healing time and hospitalization time of patients in research group were lower than those in control group, and the differences were statistically significant (p<0.05). At 72 h after operation, the platelet adhesion rate, whole blood viscosity, whole blood low-shear viscosity, hematocrit and fibrinogen level in patients in research group were lower than those in control group, and the differences were statistically significant (p<0.05). At 7th day after operation, the survival rate of replanted finger in the research group was higher than that in control group, but the necrosis rate of replanted finger and incidence rate of venous crisis were lower than those in control group, and the differences were statistically significant (p<0.05). At 6 months after operation, the nail length, sensation, two-point discrimination and mobility of distal interphalangeal joint of patients in the research group were superior to those in control group, and the differences were statistically significant (p<0.05). Unilateral digital arterial ligation combined with low molecular weight heparin has a significant effect in the treatment of severed finger without venous anastomosis, which can effectively reduce or prevent the occurrence of venous crisis, improve the survival rate of replanted finger and promote the function recovery of replanted finger, so it is worthy of clinical promotion.

Ginkgo Leaf Extract and Dipyridamole Injection as Adjuvant Treatment for Angina Pectoris: A Meta-Analysis of 41 Randomized Controlled Trials.

To provide information about the effectiveness and safety of Ginkgo Leaf Extract and Dipyridamole Injection (GD) as one adjuvant therapy for treating angina pectoris (AP) and to evaluate the relevant randomized controlled trials (RCTs) with meta-analysis. RCTs concerning AP treated by GD were searched in China Biology Medicine Disc (SinoMed), PubMed, the China National Knowledge Infrastructure Database (CNKI), the Chinese Scientifific Journals Database (VIP), Wanfang Database, Embase, and the Cochrane Library, from inception to February, 2017. The Cochrane Risk Assessment Tool was adopted to assess the methodological quality of the RCTs. The Review Manager 5.3 software was utilized to conduct the meta-analysis. A total of 41 RCTs involving 4,462 patients were included in the meta-analysis. The results indicated that the combined use of GD and Western medicine (WM) against AP was associated with a higher total effective rate [risk ratio (RR)=1.25, 95% confifidence interval (CI): 1.21-1.29, P<0.01], total effective rate of electrocardiogram (RR=1.29, 95% CI: 1.21-1.36, P<0.01). Additional, GD combined with WM could decrease the level of plasma viscosity [mean difference (MD)=-0.56, 95% CI:-0,81 to-0.30, P<0.01], fifibrinogen [MD=-1.02, 95% CI:-1.50 to-0.54, P<0.01], whole blood low shear viscosity [MD=-2.27, 95% CI:-3.04 to-1.49, P<0.01], and whole blood high shear viscosity (MD=-0.90, 95% CI: 1.37 to-0.44, P<0.01). Comparing with receiving WM only, the combine use of GD and WM was associated with a better curative effect for patients with AP. Nevertheless, limited by the methodological quality of included RCTs more large-sample, multi-center RCTs were needed to confifirm our fifindings and provide further evidence for the clinical utility of GD.

Tailoring yield stress and viscosity of concentrated microgel suspensions by means of adding immiscible liquids

Adding a small amount of secondary immiscible liquid (<1 g/100 g) to a suspension significantly alters rheological properties by creating a network of fluid bridges between particles or reinforcing an existing space-spanning network; these additional forces are termed capillary forces. Rheological properties of concentrated microgel suspensions are tunable by compositional and processing measures including solid content or particle size distribution; however, these approaches may lead to technical difficulties and further processing steps. This study aimed to test the effect of adding a small amount of oil on the rheological properties of fat-free fresh cheese, a water-continous concentrated suspension of dairy microgel particles. A significant increase of the low-shear viscosity (<1/s) and yield stress was observed by blending food-grade canola oil. Confocal scanning laser microscopy showed oil distribution between microgel particles and no apparent microstructural changes.

The rheology of liquid elemental sulfur across the λ-transition

Seventy million tons of sulfur were produced worldwide in 2016. Much of the transportation and handling of molten sulfur require sulfur pumps which are challenging to operate due to the anomalous behavior of sulfur's liquid viscosity at temperatures near its λ-transition region. Sulfur's viscosity decreases from ca. 30 × 10−2 to ca. 7 × 10−2 Pa s when heating from the melt at T = 115 °C and then increases dramatically at T > 160 °C to a maximum of 93 000 × 10−2 Pa s at T = 187 °C. While the temperature of this viscosity transition is well known, no shear related information can be found in the literature and previous low-shear data do not address thermal hysteresis behavior (viscosity differences for cooling or heating) when sulfur is heated beyond 210 °C. This work is focused on reinvestigating the low-shear viscosity of molten sulfur which was initially studied by Bacon and Fanelli [J. Am. Chem. Soc. 65, 639–648 (1943)] and the effects of high-shear. The rheology of molten sulfur was studied using an Anton-Paar MCR 302 rheometer equipped with a 1000 bars pressure cell. Viscosity profiles, including attenuation during heating or cooling are discussed, as well as the rheological behavior of molten sulfur encountered in pipe flow and pumping shear regions. Data were used to fit a semiempirical equation based on a previous reptation model. In addition, critical shear rates were measured and reported, where liquid sulfur becomes non-Newtonian at high-shear and in regions where polymerization is significant.

Evaluation of efficacy and safety of Reteplase and Alteplase in the treatment of hyper-acute cerebral infarction.

Objective: The present study aimed to investigate the efficacy and safety of Reteplase (rPA) and Alteplase (rt-PA) in the treatment of hyper-acute cerebral infarction (CI).Methods: Six hundred and eleven patients with hyper-acute CI selected from September 2014 to September 2016 were assigned into the aspirin, rt-PA, rPA, rt-PA + aspirin, and rPA + aspirin groups based on their willingness. The difference of efficacy in five groups were evaluated with National Institute of Health Stroke Scale (NIHSS), modified rankin scale (mRS), and Barthel Index (BI). Coagulation function, blood lipid, and hemodynamics were analyzed. The safety differences were compared by observing the adverse reactions.Results: Compared with the rt-PA, rPA, and aspirin groups, NIHSS score, mRS score, the incidence of non- and symptomatic cerebral hemorrhage as well as the rate of adverse reactions were decreased, while BI were increased in the rt-PA + aspirin and rPA + aspirin groups after treatment. Compared with the rt-PA and rPA groups, total cholesterol (TC), triacylglycerol (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) levels were lower, whereas the hematocrit, whole blood high shear viscosity, whole blood low shear viscosity, plasma viscosity, erythrocyte electrophoresis time, fibrinogen, erythrocyte sedimentation rate (ESR), K value in blood sedimentation equation, and the comprehensive abnormality degree of blood rheology were higher in the rt-PA + aspirin and rPA + aspirin groups.Conclusion: The efficacy and safety of rt-PA or rPA combined with aspirin in the treatment of hyper-acute CI were better than those of rPA or rt-PA monotherapy.

Effects of epidural block on coagulation and hemorheology indicators in patients undergoing gynecological laparoscopic surgery

Objective To learn the effects of epidural block on coagulation and hemorheology indicators in patients undergoing gynecological laparoscopic surgery. Methods 166 patients undergoing gynecological laparoscopic surgery were randomly divided into control group(n=77) and observation group(n=89) by the random number table method. The anesthesia induction and anesthesia maintenance methods were the same in the two groups, while the observation group was given epidural block analgesia. The operation time, intraoperative blood loss and intraoperative transfusion volume were compared between the two groups, and visual analogue scale(VAS) was used to evaluate the degree of postoperative pain. Before anesthesia, 15min after pneumoperitoneum, 30min after pneumoperitoneum, 30min after pneumoperitoneum stopped, 24h after operation and 48h after operation were set up as T0, T1, T2, T3, T4 and T5. The prothrombin time(PT), fibrinogen(Fib), activated partial thromboplastin time(APTT), two D-dimer content(D-D) were observed. And hemorheological indicators, including plasma viscosity, blood viscosity(low shear, medium shear, high shear), red blood cell aggregation were observed. Results There were no statistically significant differences between the two groups in the operation time, intraoperative blood loss and the amount of intraoperative infusion(t=0.638, 1.571, 1.601, all P>0.05). The VAS score of the observation group[(1.8±0.6)points]was lower than that of the control group(t=17.444, P<0.05). At T1, T2, T3 and T4, APTT of the control group were lower than those at T0, APTT of the control group were lower than that of the observation group(all P<0.05). At T1, T2, T3, T4 and T5, Fib and D-D of the two groups were higher than those at T0, Fib and D-D of the control group were higher than those of the observation group(t=3.003, 5.056, 4.695, 6.173, 2.539, 3.473, 3.041, 8.831, 2.612, 10.746, all P<0.05). At T1, plasma viscosity, low shear blood viscosity, middle shear blood viscosity, high shear blood viscosity and erythrocyte aggregation of the observation group were(1.28±0.18)mPa/s, (9.53±0.79)mPa/s, (6.09±0.89)mPa/s, (4.31±0.75)mPa/s, (1.41±0.21), respectively, which were lower than those at T0(t=2.805, 4.148, 4.276, 4.497, 6.804, all P<0.05). At T2, T3, T4 and T5, plasma viscosity, low shear blood viscosity, blood viscosity, blood high cut viscosity, erythrocyte aggregation of the control group were higher than those at T0(all P<0.05). At T1, T2, T3, T4, T5, plasma viscosity, low shear viscosity of blood, cutting blood viscosity, high shear blood viscosity and erythrocyte aggregation of the observation group were lower than those of control group(all P<0.05). Conclusion Epidural blockade can improve the coagulation function and hemorheology indicators of patients undergoing gynecological laparoscopic surgery, it has good clinical application value. Key words: Analgesia, epidural; Laparoscopes; Gynecologic surgical procedures; Hemagglutination; Hemorheology

Effect of high-intensity alternating magnetic field on viscosity of sheep blood

To explore the changes of blood viscosity in high-intensity alternating magnetic field and the mechanisms. Methods: Five adult sheep were randomly selected and the blood samples were placed in high-intensity alternating magnetic field. Before and after exposure, the blood samples were taken and divided into 2 groups: a control group and a magnetic field group. The blood rheology and transmission electron microscopy (TEM) were performed. Results: Compared to the control group, the high shear viscosity of whole blood was decreased in the magnetic field group (P<0.05); the whole blood low shear viscosity and plasma viscosity were also decreased (both P<0.01). TEM showed the changes in red blood cell morphology and the double concave disc curvature. The radian of double concave disc and cell volume in the magnetic field group was larger than those in the control group. Conclusion: The high intensity alternating magnetic field may affect the distribution of surface charge and molecular current in blood cells, which in turn decrease the aggregation of cells and the blood viscosity.

Extensional and shear rheology of okra hydrocolloid–saliva mixtures

This is an investigation of the shear and extensional properties of okra polysaccharide–saliva mixtures, intended to model the mechanical behavior a food hydrocolloid during oral processing. Shear measurements show that incorporation of okra mucilage in saliva interferes with the self-assembly of salivary mucins, with partly detrimental effects on the low-shear viscosity of the mixture. This is counter-acted by excluded volume effects, as the overall concentration of macromolecules in the mixture reaches the semi-dilute regime. Particle tracking confirms the lack of direct interactions between the two polymeric populations. The contribution of extensional viscosity to the overall behavior of okra hydrocolloid–saliva mixtures is dominant, at about one to two orders of size higher than the equivalent shear values. The Trouton ratio values are in the order of tens or hundreds for the range of concentrations and deformation rates under study. Although the extensional viscosity dominates viscous flow, the two types of flow are equally important concerning the elastic behavior, giving insight on the mechanical behavior of mucilages in the oral cavity.

Moxibustion at Geshu (BL 17) for diabetic limb arterial obliteration at early stage

To compare the efficacy differences between moxibustion at Geshu (BL 17) and oral administration of cilostazol on diabetic limb arterial obliteration (DLAO) at early stage as well as the impacts on hemorheology and arterial inner dimension of lower extremity. Seventy patients of DLAO at early stage were randomly divided into an observation group and a control group, 35 cases in each one. The two groups were treated with regular treatment of blood glucose and blood lipid. The patients in the control group was treated with oral administration of cilostazol, 50 mg, twice a day; the patients in the observation group were treated with moxibustion at Geshu (BL 17), once a day. The consecution treatment of two weeks constituted one session, and totally 4 sessions were given. The total syndrome score, hemorheology index (including low and high shear viscosity of blood, plasma viscosity, hematocrit and erythrocyte aggregation index) and arterial inner dimension of lower extremity (including popliteal artery, posterior tibial artery and dorsalis pedis artery) were compared before and after treatment. Compared with those before treatment, the total syndrome score, hemorheology index and arterial inner dimension of lower extremity were significantly improved after treatment in the two groups (all P<0.05). The total syndrome score, hemorheology index in the observation group were superior to those in the control group (all P<0.05), but the improvement of arterial inner dimension of lower extremity was not significantly different between the two groups (P>0.05). After treatment, the total effective rate was 91.4% (32/35) in the observation group, which was significantly superior to 85.7% (30/35) in the control group (P<0.05). Moxibustion at Geshu (BL 17) is superior to oral administration of cilostazol for DLAO at early stage, which could effectively improve the clinical symptoms, blood flow and blood vessel and increase the blood flow of lower limb.