Dependence Viscosity of Temperature and Shear Rate for Vegetable oil used as Biodegradable Lubricant

2020 ◽  
Vol 36 (03) ◽  
pp. 563-566
Author(s):  
Ioana Stanciu
Keyword(s):  
Shear Rate ◽  
Vegetable Oil ◽  
Biodegradable Lubricant

scholarly journals Study Rheological Behavior of Rapeseed Oils Compared to Mineral Oil

2021 ◽  
Vol 37 (1) ◽  
pp. 247-249
Author(s):  
Ioana Stanciu
Keyword(s):  
Shear Rate ◽  
Rheological Behavior ◽  
Dynamic Viscosity ◽  
Rapeseed Oil ◽  
Mineral Oil ◽  
Dynamic Shear ◽  
Dynamic Temperature ◽  
Biodegradable Lubricant

This article presents the dependence of dynamic temperature viscosity and shear rate for rapeseed oils used as biodegradable lubricant and SAE 10W. The studied rheograms show the dependence of the dynamic shear rate viscosity as well as the dependence of the dynamic temperature viscosity. From the rheograms there is a decrease in the dynamic viscosity with temperature and shear rate for the two oils. The dynamic viscosity of rapeseed oil is most strongly influenced by the shear rate compared to the studied SAE 10W oil. The rheological behavior of rapeseed and mineral oil SAE 10W was studied with the Haake VT 550 viscometer at temperatures between 40 and 1000C.

scholarly journals Dynamic Viscosity As A Function Of Shear Rate: The Comparison Of Established Rheological Models With The Newly Derived Rheological Model For The Estimation Of Zero– And Infinite–Shear Rate Viscosity Of Vegetable Oils

2012 ◽  
Author(s):  
Eng Giap Sunny Goh ◽  
Azira Amran
Keyword(s):  
Experimental Data ◽  
Shear Rate ◽  
Vegetable Oil ◽  
Rheological Model ◽  
Physical Parameters ◽  
Extreme Conditions ◽  
Newtonian Viscosity ◽  
Rheological Models ◽  
Rate Region ◽  
Low Shear

Kelikatan merupakan salah satu daripada parameter fizikal penting yang memerlukan pengukuran dengan kejituan, dan supaya ia dapat diwakili dengan persamaan reologi untuk membolehkan interpolasi nilai kelikatan yang tidak diketahui. Persamaan akan mempunyai kelebihan tambahan jika anggaran persamaan mampu memberi anggaran jitu penentuluaran. Sesetengah persamaan adalah mementingkan kejituan ramalan kelikatan dalam julat nilai eksperimen, sementara yang lain pula boleh membuat jangkaan kelikatan pada keadaan lampau, contohnya, kelikatan pada keadaan infiniti– and sifar–keterikan. Persamaan Cross and Carreau mampu untuk memberi nilai kelikatan pada keadaan lampau, tetapi anggaran keterikan awalan tidak boleh ditentusahkan jika data eksperimen tidak menunjukkan kewujudan sifat Newtonian. Dalam kajian ini, minyak tumbuhan kelapa, jagung, canola, dan soya dikaji dengan menggunakan viskometer pada keterikan yang berlainan, 3.9 – 131.6 s–1, dan keterikan adalah dilakukan pada suhu, 50 dan 90°C. Data eksperimen dipadankan dengan persamaan–persamaan reologi yang terkenal, dan kemudiannya, satu persamaan reologi baru diperkenalkan sebagai persamaan altenatif kepada pengiraan kelikatan pada kawasan keterikan rendah. Infiniti–keterikan kelikatan daripada persamaan baru adalah setara dengan nilai–nilai daripada persamaan–persamaan reologi terkenal. Di samping itu, keputusan menunjukkan kelikatan minyak tumbuhan mempunyai ciri pseudoplastic, dan data eksperimen dapat dimodelkan dengan persamaan baru dengan baik (R2 > 0.96). Kata kunci: Kelikatan; keterikan; reologi; minyak tumbuhan; Newtonian Viscosity is one of the most important physical parameters that need proper measurement in terms of its accuracy, and to be fitted by rheological model to enable interpolation for unknown viscosity. It would be an advantage if the model estimation could be extended for viscosity extrapolation with reliability. Some models are concerned with the accuracy of predicting viscosity within the experimental range value, while others able to predict viscosity at extreme conditions, for instance, viscosity at infinite– and zero–shear rate conditions. Cross and Carreau are able to model viscosity at extreme conditions, but its estimation value at very low shear rate region could not be justified if the experimental data does not signify the presence of Newtonian behaviour. In this study, coconut, corn, canola, and soy oils were investigated with a viscometer at different shear rates, 3.9 – 131.6 s–1, and were sheared at specific temperatures, 50 and 90°C. The experimental data were curve–fitted with wellknown rheological models, and then, a new rheological model was proposed as an alternative equation for viscosity estimation at low shear rate region. Infinite–shear rate viscosity from the new model is consistent with the estimation from well–known models. In addition, results showed that vegetable oil has the characteristic of a pseudoplastic, and the experimental data were well fitted by the new proposed model (R2 > 0.96). Key words: Viscosity; shear rate; rheology; vegetable oil; Newtonian

Adenosine Diphosphate-Induced Aggregation of Human Platelets in Flow Through Tubes: III. Shear and Extrinsic Fibrinogen-Dependent Effects

1994 ◽  
Vol 71 (01) ◽  
pp. 078-090 ◽  
Author(s):  
H L Goldsmith ◽  
M M Frojmovic ◽  
Susan Braovac ◽  
Fiona McIntosh ◽  
T Wong
Keyword(s):  
Shear Rate ◽  
Single Cells ◽  
Adenosine Diphosphate ◽  
Human Platelets ◽  
Size Analysis ◽  
Fibrinogen Concentration ◽  
Human Fibrinogen ◽  
Shear Rates ◽  
Rate Dependent ◽  
Induced Aggregation

SummaryThe effect of shear rate and fibrinogen concentration on adenosine diphosphate-induced aggregation of suspensions of washed human platelets in Poiseuille flow at 23°C was studied using a previously described double infusion technique and resistive particle counter size analysis (1). Using suspensions of multiple-centrifuged and -washed cells in Tyrodes-albumin [3 × 105 μl−1; (17)] with [fibrinogen] from 0 to 1.2μM, the, rate and extent of aggregation with 0.7 μM ADP in Tyrodes-albumin were measured over a range of mean transit times from 0.2 to 43 s, and at mean tube shear rates, Ḡ, = 41.9, 335 and 1,335 s−1. As measured by the decrease in singlet concentration, aggregation at 1.2 μM fibrinogen increased with increasing Ḡ up to 1,335 s1, in contrast to that previously reported in citratcd plasma, in which aggregation reached a maximum at Ḡ = 335 s−1. Without added fibrinogen, there was no aggregation at Ḡ = 41.9 s1; at Ḡ = 335 s1, there was significant aggregation but with an initial lag time, aggregation increasing further at Ḡ = 1,335 s−1. Without added fibrinogen, aggregation was abolished at all Ḡ upon incubation with the hexapeptide GRGDSP, but was almost unaffected by addition of an F(ab’)2 fragment of an antibody to human fibrinogen. Aggregation in the absence of added fibrinogen was also observed at 37°C. The activation of the multiple-washed platelets was tested using flow cytometry with the fluorescently labelled monoclonal antibodies FITC-PAC1 and FITC-9F9. It was shown that 57% of single cells in unactivated PRT expressed maximal GPIIb-IIIa fibrinogen receptors (MoAb PAC1) and 54% expressed pre-bound fibrinogen (MoAb 9F9), with further increases on ADP activation. However, incubation with GRGDSP and the F(ab’)2 fragment did not inhibit the prebound fibrinogen. Moreover, relatively unactivated cells (8% expressing receptor, 14% prebound fibrinogen), prepared from acidified cPRP by single centrifugation with 50 nM of the stable prostacyclin derivative, ZK 36 374, and resuspension in Tyrodes-albumin at 5 × 104 μl−1, aggregated with 2 and 5 μM ADP at Ḡ = 335 and 1,335 s−1 in the absence of added fibrinogen. We therefore postulate that a protein such as von Willebrand factor, secreted during platelet isolation or in flow at sufficiently high shear rates, may yield the observed shear-rate dependent aggregation without fibrinogen.

Platelet and Shear Rate Promote Tumor Cell Adhesion to Human Endothelial Extracellular Matrix - Absence of a Role for Platelet Cyclooxygenase

1989 ◽  
Vol 61 (03) ◽  
pp. 485-489 ◽  
Author(s):  
Eva Bastida ◽  
Lourdes Almirall ◽  
Antonio Ordinas
Keyword(s):  
Cell Adhesion ◽  
Shear Rate ◽  
Tumor Cell ◽  
Umbilical Vein ◽  
Blood Platelets ◽  
Flow Conditions ◽  
Tumor Cell Adhesion ◽  
Rate Dependent ◽  
Static Conditions

SummaryBlood platelets are thought to be involved in certain aspects of malignant dissemination. To study the role of platelets in tumor cell adherence to vascular endothelium we performed studies under static and flow conditions, measuring tumor cell adhesion in the absence or presence of platelets. We used highly metastatic human adenocarcinoma cells of the lung, cultured human umbilical vein endothelial cells (ECs) and extracellular matrices (ECM) prepared from confluent EC monolayers. Our results indicated that under static conditions platelets do not significantly increase tumor cell adhesion to either intact ECs or to exposed ECM. Conversely, the studies performed under flow conditions using the flat chamber perfusion system indicated that the presence of 2 × 105 pl/μl in the perfusate significantly increased the number of tumor cells adhered to ECM, and that this effect was shear rate dependent. The maximal values of tumor cell adhesion were obtained, in presence of platelets, at a shear rate of 1,300 sec-1. Furthermore, our results with ASA-treated platelets suggest that the role of platelets in enhancing tumor cell adhesion to ECM is independent of the activation of the platelet cyclooxygenase pathway.

The Effect of Red Blood Cells on the ADP-induced Aggregation of Human Platelets in Flow Through Tubes

1990 ◽  
Vol 63 (01) ◽  
pp. 112-121 ◽  
Author(s):  
David N Bell ◽  
Samira Spain ◽  
Harry L Goldsmith
Keyword(s):  
Platelet Aggregation ◽  
Shear Rate ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Platelet Rich Plasma ◽  
Mean Transit Time ◽  
White Blood Cells ◽  
Aggregate Size ◽  
Human Platelets ◽  
Induced Aggregation

SummaryThe effect of red blood cells, rbc, and shear rate on the ADPinduced aggregation of platelets in whole blood, WB, flowing through polyethylene tubing was studied using a previously described technique (1). Effluent WB was collected into 0.5% glutaraldehyde and the red blood cells removed by centrifugation through Percoll. At 23°C the rate of single platelet aggregtion was upt to 9× greater in WB than previously found in platelet-rich plasma (2) at mean tube shear rates Ḡ = 41.9,335, and 1,920 s−1, and at both 0.2 and 1.0 µM ADP. At 0.2 pM ADP, the rate of aggregation was greatest at Ḡ = 41.9 s−1 over the first 1.7 s mean transit time through the flow tube, t, but decreased steadily with time. At Ḡ ≥335 s−1 the rate of aggregation increased between t = 1.7 and 8.6 s; however, aggregate size decreased with increasing shear rate. At 1.0 µM ADP, the initial rate of single platelet aggregation was still highest at Ḡ = 41.9 s1 where large aggregates up to several millimeters in diameter containing rbc formed by t = 43 s. At this ADP concentration, aggregate size was still limited at Ḡ ≥335 s−1 but the rate of single platelet aggregation was markedly greater than at 0.2 pM ADP. By t = 43 s, no single platelets remained and rbc were not incorporated into aggregates. Although aggregate size increased slowly, large aggregates eventually formed. White blood cells were not significantly incorporated into aggregates at any shear rate or ADP concentration. Since the present technique did not induce platelet thromboxane A2 formation or cause cell lysis, these experiments provide evidence for a purely mechanical effect of rbc in augmenting platelet aggregation in WB.

Evaluation of reversed-phase thin layer chromatographic protocol to detect vegetable oil or fat in milk

2019 ◽  
Vol 72 (04) ◽  
pp. 370-374
Author(s):  
Sukthija . ◽  
Vivek Sharma . ◽  
Sumit Arora . ◽  
Richa Singh . ◽  
P N Raju . ◽  
...  
Keyword(s):  
Thin Layer ◽  
Vegetable Oil ◽  
Reversed Phase
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