Mechanical and Tribological Studies of SU-8 Composites Filled With UHMWPE and Gum Acacia Under Dry and Bovine Serum Albumin Lubricated Conditions

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Jaswant K. Hirwani ◽  
Sujeet K. Sinha

Abstract SU-8 polymer was mixed with ultrahigh-molecular weight polyethylene (UHMWPE) particles in various weight percentages (wt%) to make composites. Uniform distribution of filler material was confirmed by optical microscopy imaging. Cross-sectional scanning electron microscopy (SEM) analysis showed the formation of fibrillar structure of UHMWPE which helped bind UHMWPE particles with SU-8 matrix. Gum acacia made a coating on the UHMWPE particles and helped in binding with the matrix. The compressive Young’s modulus and strength of the composites were found to decrease with UHMWPE filler addition. The composites were tested in ball-on-disk tribometer using 12 mm diameter stainless steel (grade 304) ball under a normal load of 20 N and sliding speed of 32 mm/s. SU-8 with 25 wt% of UHMWPE showed coefficient of friction of 0.1 and specific wear-rate of 6.27 × 10−5 mm3/Nm which were 52% and 61%, respectively, lower in comparison with those of bulk UHMWPE tested in aqueous solution of bovine serum albumin (BSA). Adding 10 wt% of gum acacia to the SU-8/UHMWPE composite had beneficial effects on the wear-rate as the specific wear-rate of this hybrid composite further dropped to 4.6 × 10−5 mm3/Nm which was 71% lower than that of bulk UHMWPE.

2021 ◽  
Vol 11 (9) ◽  
pp. 3956
Author(s):  
Wilhelm Robert Glomm ◽  
Peter Patrick Molesworth ◽  
Eugenia Mariana Sandru ◽  
Le Thuy Truong ◽  
Anders Brunsvik ◽  
...  

Most liquid food flavours such as essential oils are volatile and prone to degradation in the presence of oxygen, light, moisture and high temperatures. Microencapsulation of volatile ingredients prior to use in food or beverages is a commonly used process to limit loss and degradation of flavours and aromas during processing and storage. Here, peppermint essential oil was microencapsulated via complex coacervation using a combination of bovine serum albumin and gum Acacia as wall materials. The resulting core-shell microcapsules were chemically crosslinked with a modified food-grade starch, and subsequently spray dried, resulting in dry microcapsules which could be easily redispersed in aqueous solutions. Microcapsule formation and stability, as well as microencapsulation yield of peppermint oil, were investigated as a function of polymer concentration, core material load/wall thickness and crosslinker concentration. The crosslinked peppermint oil microcapsules were spherical and mononuclear both before and after spray drying and redispersion, whereas control coacervate samples without crosslinker did not withstand the spray drying process. Microencapsulation yield as analysed by GC-MS showed no loss of peppermint oil during or after complex coacervation, and 54% loss after spray drying for the best combination of Polymer:Oil ratio and crosslinker concentration used here, indicating good overall protection of the core material.


Author(s):  
G. D. Gagne ◽  
M. F. Miller

We recently described an artificial substrate system which could be used to optimize labeling parameters in EM immunocytochemistry (ICC). The system utilizes blocks of glutaraldehyde polymerized bovine serum albumin (BSA) into which an antigen is incorporated by a soaking procedure. The resulting antigen impregnated blocks can then be fixed and embedded as if they are pieces of tissue and the effects of fixation, embedding and other parameters on the ability of incorporated antigen to be immunocyto-chemically labeled can then be assessed. In developing this system further, we discovered that the BSA substrate can also be dried and then sectioned for immunolabeling with or without prior chemical fixation and without exposing the antigen to embedding reagents. The effects of fixation and embedding protocols can thus be evaluated separately.


1981 ◽  
Vol 46 (03) ◽  
pp. 645-647 ◽  
Author(s):  
M A Orchard ◽  
C Robinson

SummaryThe biological half-life of prostacyclin in Krebs solution, human cell-free plasma or whole blood was measured by bracket assay on ADP-induced platelet aggregation. At 37°C, pH 7.4, plasma and blood reduced the rate of loss of antiaggregatory activity compared with Krebs solution. The protective effect of plasma was greater than that of whole blood. This effect could be partially mimicked by the addition of human or bovine serum albumin to the Krebs solution. The stabilisation afforded by human serum albumin was dependent on the fatty acid content of the albumin, although this was less important for bovine serum albumin.


1974 ◽  
Vol 75 (1) ◽  
pp. 133-140 ◽  
Author(s):  
B. E. Senior

ABSTRACT A radioimmunoassay was developed to measure the levels of oestrone and oestradiol in 0.5–1.0 ml of domestic fowl peripheral plasma. The oestrogens were extracted with diethyl ether, chromatographed on columns of Sephadex LH-20 and assayed with an antiserum prepared against oestradiol-17β-succinyl-bovine serum albumin using a 17 h incubation at 4°C. The specificity, sensitivity, precision and accuracy of the assays were satisfactory. Oestrogen concentrations were determined in the plasma of birds in various reproductive states. In laying hens the ranges of oestrone and oestradiol were 12–190 pg/ml and 29–327 pg/ml respectively. Levels in immature birds, in adult cockerels and in an ovariectomized hen were barely detectable. The mean concentrations of oestrone and oestradiol in the plasma of four non-laying hens (55 pg/ml and 72 pg/ml respectively) and one partially ovariectomized hen (71 pg/ml and 134 pg/ml respectively) were well within the range for laying hens. It is evident that the large, yolk-filled follicles are not the only source of oestrogens in the chicken ovary.


2013 ◽  
Vol 30 (2) ◽  
pp. 232
Author(s):  
Fan LIU ◽  
Yuanqin ZHANG ◽  
Zhijin ZHANG

2012 ◽  
Vol 18 (2) ◽  
pp. 287
Author(s):  
Zhiwei LIN ◽  
Zhengfu TAI ◽  
Zhongmin WAN ◽  
Fei WANG ◽  
Ningfei LEI

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