Search results for "SLI"
showing 10 items of 1729 documents
Biodegradable Polymers for the Production of Nets for Agricultural Product Packaging
2021
It is well known that the need for more environmentally friendly materials concerns, among other fields, the food packaging industry. This regards also, for instance, nets used for agricultural product (e.g., citrus fruits, potatoes) packaging. These nets are typically manufactured by film blowing technique, with subsequent slicing of the films and cold drawing of the obtained strips, made from traditional, non-biodegradable polymer systems. In this work, two biodegradable polymer systems were characterized from rheological, processability, and mechanical points of view, in order to evaluate their suitability to replace polyethylene-based polymer systems typically used for agricultural prod…
Risk of failure in existing RC balcony and strength verification under degradation phenomena
2020
Abstract In the present paper, the safety conditions of reinforced concrete (RC) balconies subject to degradation phenomena caused by carbonation, presence of chlorides or water infiltration were examined. After a brief review of the typical damages of balconies occurring with detachments of plaster and bricks expulsion, some cases of collapses of balconies recently occurred were presented. Therefore, a calculation model was proposed for a hand verification of the flexural and shear strength of existing corroded T beams cast in place of lightened RC orthotropic slabs forming the balcony and for the calculus of deflection including slippage of steel bars. Diffused and pitting corrosion on st…
Slip Flow Over Structured Surfaces with Entrapped Microbubbles
2008
On hydrophobic surfaces, roughness may lead to a transition to a superhydrophobic state, where gas bubbles at the surface can have a strong impact on a detected slip. We present two-phase lattice Boltzmann simulations of a Couette flow over structured surfaces with attached gas bubbles. Even though the bubbles add slippery surfaces to the channel, they can cause negative slip to appear due to the increased roughness. The simulation method used allows the bubbles to deform due to viscous stresses. We find a decrease of the detected slip with increasing shear rate which is in contrast to some recent experimental results implicating that bubble deformation cannot account for these experiments.…
Scaffolds based on hyaluronan crosslinked with a polyaminoacid: Novel candidates for tissue engineering application
2008
New porous scaffolds, with a suitable hydrolytic and enzymatic degradation, useful for tissue engineering applications have been obtained by a carbodiimide mediated reaction between hyaluronan (HA) and a synthetic polymer with a polyaminoacid structure such as α,β-polyaspartylhydrazide (PAHy). Scaffolds with a different molar ratio between PAHy repeating units and HA repeating units have been prepared and characterized from a chemical and physicochemical point of view. Tests of indirect and direct cytotoxicity, cell adhesion, and spreading on these biomaterials have been performed by using murine L929 fibroblasts. The new biomaterials showed a good cell compatibility and ability to allow ce…
Recrystallization in subsurface zone seen by positron annihilation
2010
Abstract The paper presents studies of the defect distribution, detected by the positron annihilation method in the subsurface zone (SZ) of copper samples after dry sliding wear. It takes advantage of a new experimental technique based on scanning of the positron implantation profile. It allowed us to detect the defect profile in copper to the depth of 200 μm in a nondestructive way and study isochronal annealing behavior of this profile. We determined that annealing induces a recrystallization process which runs faster close to the surface than in deeper regions. After sliding, the complete recrystallization of the substructure takes place at temperature c.a. 600 °C. Some changes in the de…
Molecular Scale Study of Domain Boundaries and Frictional Stick-Slip Motion on Lipid Bilayers
1995
A highly 2-dimensional (2D) anisotropic crystal formation of an organic one component lipid bilayer system is presented measured in air by atomic force microscopy. 2D domains with different crystal orientation could be observed. Their molecularly smooth domain boundaries are perceived to be either commensurable or incommensurable lattice joints. Differences in the orientation of the crystal lattice affects dynamic friction on the micrometer scale. High resolution friction images provide stick-slip motions depending on the scan direction in respect to the lattice orientation. It is shown that sliding friction can be determined by an averaged value of the molecular stick-slip motion of the fr…
Amorphous silica between confining walls and under shear: a computer simulation study
2002
Molecular dynamics computer simulations are used to investigate a silica melt confined between walls at equilibrium and in a steady-state Poisseuille flow. The walls consist of point particles forming a rigid face-centered cubic lattice and the interaction of the walls with the melt atoms is modelled such that the wall particles have only a weak bonding to those in the melt, i.e. much weaker than the covalent bonding of a Si-O unit. We observe a pronounced layering of the melt near the walls. This layering, as seen in the total density profile, has a very irregular character which can be attributed to a preferred orientational ordering of SiO4 tetrahedra near the wall. On intermediate lengt…
Evidence of quantum phase slip effect in titanium nanowires
2012
Electron transport properties of titanium nanowires were experimentally studied. Below the effective diameter $\lesssim$ 50 nm all samples demonstrated a pronounced broadening of the $R(T)$ dependencies, which cannot be accounted for thermal flcutuations. An extensive microscopic and elemental analysis indicates the absence of structural or/and geometrical imperfection capable to broaden the the $R(T)$ transition to such an extent. We associate the effect with quantum flucutuations of the order parameter.
Study and evaluation of fretting critical slip conditions by applying the design of experiments method
2006
Tribological systems are complex systems that require a multi-disciplinary (mechanical, material, physico-chemical) approach where numerous influence factors can be involved. To characterize a contact couple, the intrinsic parameters of the materials as well as the parameters related to the contact loading and the surrounding environment need to be taken into account. Fretting analysis, by means of running condition-fretting maps (RCFM), allows the behavior of the contact couple to be taken into account and to predict the boundary between partial slip and gross slip conditions. This article presents the study of a steel/polycarbonate couple during fretting tests. The study was carried out b…
Thermal stability of ethylene copolymers with multi-alkenylsilsesquioxane comonomers synthesized by organometallic catalyst - Effect of copolymer str…
2020
Abstract This study was focused on thermal properties of ethylene copolymers with di-, tri- and tetra-alkenylsilsesquioxanes (POSS) synthesized by ansa-metallocene complex. Ethylene copolymers with multi-alkenyl POSS were characterized by different thermal behavior depending on the kind of POSS comonomer and its content, as well as the copolymer structure. The copolymers differed in the incorporation way of POSS into the polymer chain (linear and crosslinked structure), content of specific unsaturation groups, molecular weight, as well as heterogeneity of polymer chain compositions. It was found that the kind and content of unsaturation groups in E/POSS copolymers played a significant role …