ICE ADHESION

Results of shear tests for the system ice – stainless steel and ice – optically flat fused quartz as a function of the rate of shear and roughness of the steel surfaces are presented. The adhesive strength decreased with decreasing roughness of steel surfaces, and the force versus time curves for smooth steel plates resembled those of two solids sliding over each other with a liquid layer between them. This behavior was especially evident in the case of the optically flat quartz. The adhesive strength as a function of rate of shear was linear for both ice – stainless steel and ice – quartz but there were indications of yield values. The results agree with the assumption of a liquidlike layer on ice. Ratios of viscosity coefficient to layer thickness were evaluated for both systems, and viscosity coefficients are estimated. Shear experiments on thin water films between glass plates support the assumption of a liquidlike layer on ice. The importance of interfacial free energy considerations is pointed out.

Download Full-text

Investigating the Effect of Hydrophilic Surface Modification on Droplet Evaporation

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1120-1121.779 ◽

2015 ◽

Vol 1120-1121 ◽

pp. 779-784

Author(s):

Shen Chun Wu ◽

Sin Jie Lin ◽

Dawn Wang ◽

Yau Ming Chen

Keyword(s):

Stainless Steel ◽

Surface Modification ◽

Thin Layers ◽

Steel Plates ◽

Transfer Enhancement ◽

Flat Plates ◽

Assembly Method ◽

Evaporation Heat ◽

Steel Surfaces ◽

The Relationship

In this study, surface modification of stainless steel flat plates was performed using nanoscale bilayers assembly method to increase the surface’s hydrophilicity and enhance evaporation. Thin layers of SiO2 nanoparticles layered onto the stainless steel surfaces were used to modify their surface properties, and the relationship between the number of layers (0~20) and water’s hydrophilicity (surface tension) was investigated. The effects of modification on evaporation were then tested using de-ionized water. According to experimental results, surface modification was able to reduce the contact angle of water on stainless steel flat plate from the unmodified 87o to 7o at 18 layers, significantly increasing the hydrophilicity of the surface. Evaporation experiments show that the evaporation heat transfer enhancement for droplets on stainless steel plates is at least 300%.Keywords: bilayers assembly, hydrophilicity, surface modification, evaporation performance

Download Full-text

Improved Quantitative Recovery of Listeria monocytogenes from Stainless Steel Surfaces Using a One-Ply Composite Tissue

Journal of Food Protection ◽

10.4315/0362-028x-67.10.2212 ◽

2004 ◽

Vol 67 (10) ◽

pp. 2212-2217 ◽

Cited By ~ 41

Author(s):

KEITH L. VORST ◽

EWEN C. D. TODD ◽

ELLIOT T. RYSER

Keyword(s):

Stainless Steel ◽

Phosphate Buffer ◽

Phosphate Buffer Solution ◽

Steel Plates ◽

Stainless Steel Surface ◽

Disc Diffusion ◽

Buffer Solution ◽

Composite Tissue ◽

Steel Surfaces ◽

Diffusion Assay

Four sampling devices, a sterile environmental sponge (ES), a sterile cotton-tipped swab (CS), a sterile calcium alginate fiber-tipped swab (CAS), and a one-ply composite tissue (CT), were evaluated for quantitative recovery of Listeria monocytogenes from a food-grade stainless steel surface. Sterile 304-grade stainless steel plates (6 by 6 cm) were inoculated with approximately 106 CFU/cm2 L. monocytogenes strain Scott A and dried for 1 h. The ES and CT sampling devices were rehydrated in phosphate buffer solution. After plate swabbing, ES and CT were placed in 40 ml of phosphate buffer solution, stomached for 1 min and hand massaged for 30 s. Each CS and CAS device was rehydrated in 0.1% peptone before swabbing. After swabbing, CS and CAS were vortexed in 0.1% peptone for 1 min. Samples were spiral plated on modified Oxford agar with modified Oxford agar Rodac Contact plates used to recover any remaining cells from the stainless steel surface. Potential inhibition from CT was examined in both phosphate buffer solution and in a modified disc-diffusion assay. Recovery was 2.70, 1.34, and 0.62 log greater using CT compared with ES, CS, and CAS, respectively, with these differences statistically significant (P < 0.001) for ES and CT and for CAS, CS, and CT (P < 0.05). Rodac plates were typically overgrown following ES, positive after CS and CAS, and negative after CT sampling. CT was noninhibitory in both phosphate buffer solution and the modified disc-diffusion assay. Using scanning electron microscopy, Listeria cells were observed on stainless steel plates sampled with each sampling device except CT. The CT device, which is inexpensive and easy to use, represents a major improvement over other methods in quantifying L. monocytogenes on stainless steel surfaces and is likely applicable to enrichment of environmental samples.

Download Full-text

Influence of the NaIO4 Concentration on the Gelation and the Adhesive Strength of Pyrocatechol/Pyrogallol Containing Gelatin Hydrogels

Frontiers in Materials ◽

10.3389/fmats.2021.671451 ◽

2021 ◽

Vol 8 ◽

Author(s):

Florence Back ◽

Vincent Ball ◽

Youri Arntz

Keyword(s):

Stainless Steel ◽

Adhesion Strength ◽

Adhesive Strength ◽

Thermal Stabilization ◽

Steel Plates ◽

Self Healing ◽

Constant Concentration ◽

Gelation Kinetics ◽

Gelatin Gels ◽

Kinetics Of

The presence of catechol groups in hydrogels, either grafted to the constituting polymers or added in the gel formulation allow to increase the adhesion strength of such hydrogels. In this investigation, we add pyrocatechol (1,2-benzenediol) and pyrogallol (1,2,3-benzenetriol) in gelatin solution to form hydrogels using sodium periodate as an oxidant with the aim to induce interactions between pyrocatechol/pyrogallol and the gelatin chains. The gelation kinetics of the hydrogels as well as their adhesion strength and toughness are evaluated as a function of the concentration in NaIO4 for a constant concentration-10 mM-in pyrocatechol/pyrogallol. It came out that the addition of pyrogallol to gelatin (10% w/v) did not improve the adhesion strength on stainless steel when compared to a pristine gelatin gel. As an interesting finding, the addition of pyrocatechol to gelatin allowed for a major improvement of the adhesive strength between two stainless steel plates and allowed to stabilize the gel up to 50°C. However, the pyrogallol modified gelatin gels displayed no thermal stabilization compared to pristine gelatin. The major differences between pyrocatechol and pyrogallol modified gels are explained on the basis of the electrophilicity of the oxidized polyphenols. In addition, the self-healing behavior of the gelatin based gels was investigated as a function of their composition.

Download Full-text