Impact of sequential surface-modification of graphene oxide on ice nucleation

Base-washed graphene-oxide which has been sequentially modified by thiol-epoxy chemistry, results in materials with ice nucleation activity. The role of hydro-philic/phobic grafts and polymers was evaluated with the most potent functioning at just 0.25 wt %. These 2-D hybrid materials may find use in cryopreservation and fundamental studies on ice formation

Modification of surface energy in nuclear multifragmentation

Within the statistical multifragmentation model we study modifications of the surface and symmetry energy of primary fragments in the freeze-out volume. The ALADIN experimental data on multifragmentation obtained in reactions induced by high-energy projectiles with different neutron richness are analyzed. We have extracted the isospin dependence of the surface energy coefficient at different degrees of fragmentation. We conclude that the surface energy of hot fragments produced in multifragmentation reactions differs from the values extracted for isolated nuclei at low excitation. At high fragment multiplicity, it becomes nearly independent of the neutron content of the fragments.Comment: 11 pages with 13 figure

Surface modification of a polyether-urethane with RGD-containing peptides for enhanced cell attachment and signalling

Abstract of article examining the chemical modification of polyurethane with RGD-containing peptides offers a means of encouraging the adhesion, spreading and proliferation of cells cultured on its surface. This study assesses the efficacy of a modification procedure using surface analysis techniques and preliminary cell culture studies

Surface plasmon peak intensity dependence on the oxygen coverage at metal surfaces

The dependence of the surface plasmon peak intensity on a submonolayer coverage of oxygen in the reflection electron energy loss spectra has been investigated for non-monocrystalline aluminium, magnesium, and indium surfaces. It will be shown that the decrease of the surface plasmon peaks can be related to a modification of the surface plasmons dispersion relation. A simple model for this modification introduced by changes of the surface electron density profile is proposed. Parameters of this model will be determined from experimental data

Giant magnetoimpedance: new electrochemical option to monitor surface effects?

Magnetoimpedance, MI, change due to surface modification of the sensitive element caused by biofluids was studied with the aim of creating a robust sensor capable of separating the chemical surface modification from the sensing process. A MI sensor prototype with an as-quenched FeCoSiB amorphous ribbon sensitive element was designed and calibrated for a frequency range of 0.5 to 10 MHz at an intensity of the current of 60 mA. Measurements as a function of the exposure time were made, first, in a regime where chemical surface modification and sensing were separated and then, in a regime where they were not separated (in a bath for fluids). The MI variation was explained by the change of the surface magnetic anisotropy. It was shown that the magnetoimpedance effect can be successfully employed as a new electrochemical option to probe the electric features of surface-modified magnetic electrodes when the biofluid, the material of the sensitive element, and the detection conditions are properly selected and synergetically adjusted.Comment: 22 pages, 6 figure

Regulating the antibiotic drug release from ß-tricalcium phosphate ceramics by atmospheric plasma surface engineering

Calcium phosphate (CaP) ceramics are of interest in bone substitution due to their good biocompatibility and bioresorbability. Currently certain CaPs in the market are loaded with antibiotics in order to prevent infections but further control is needed over antibiotic release patterns. Cold plasmas have emerged as a useful means of modifying the interactions with drugs through surface modification of polymer materials. In this work we explore the possibility of using atmospheric pressure plasmas as a tool for the surface modification of these CaP materials with newly populated bonds and charges, with views on enabling higher loading and controlled drug release. Herein the surface modification of ß-tricalcium phosphate ceramics is investigated using an atmospheric pressure helium plasma jet as a tool for tuning the controlled release of the antibiotic doxycycline hyclate, employed as a drug model. The surface chemistry is tailored mainly by plasma jet surface interaction with an increasing O/C ratio without changes in the topography as well as by build-up of surface charges. With this surface tailoring it is demonstrated that the atmospheric plasma jet is a new promising tool that leads to the design of a control for drug release from bioceramic matrices.Peer ReviewedPostprint (author's final draft

Surface modification of polyester using chicken feather keratin hydrolysate to improve water absorbency and dye uptake

PET fiber has an intrinsic low hydrophilic character and an inactive surface which make it uncomfortable for wearing purpose. Moreover, it is difficult to colour polyester fabric other than disperse dyes. Therefore, surface modification of PET is very important to improve its absorbency and bring the possibility to dye polyester with anionic dyes by altering its surface characteristics. This research was focused on surface modification of polyester using chicken feather which involves serine as the most abundant amino acid with hydroxyl groups. The treated polyester fabric using 20ml/L concentration of chicken feather extract showed improved water drop absorbency from 45 into 3 seconds and the reactive dye uptake by 36 folds from 0.15 to 5.37 K/S values

Designing pulse laser surface modification of H13 steel using response surface method

This paper presents a design of experiment (DOE) for laser surface modification process of AISI H13 tool steel in achieving the maximum hardness and minimum surface roughness at a range of modified layer depth. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, overlap percentage and pulse repetition frequency (PRF). The response surface method with Box-Behnken design approach in Design Expert 7 software was used to design the H13 laser surface modification process. Metallographic study and image analysis were done to measure the modified layer depth. The modified surface roughness was measured using two-dimensional surface profilometer. The correlation of the three laser processing parameters and the modified surface properties was specified by plotting three-dimensional graph. The hardness properties were tested at 981 mN force. From metallographic study, the laser modified surface depth was between 37 8m and 150 8m. The average surface roughness recorded from the 2D profilometry was at a minimum value of 1.8 8m. The maximum hardness achieved was between 728 and 905 HV0.1.These findings are significant to modern development of hard coatings for wear resistant applications

Flex flap

To provide flap with large upper surface radius as required for airplanes with over-the-wing blowing, distort upper surface of flap by actuator. Flap can be used as control surface at leading as well as trailing edges and, with minor modification, as variant of Jacobs-Hurkamp air flap

Surface modification of hydrophobic polymers for improvement of endothelial cell-surface interactions

The aim of this study is to improve the interaction of endothelial cells with polymers used in vascular prostheses. Polytetrafluoroethylene (PTFE; Teflon) films were treated by means of nitrogen and oxygen plasmas. Depending on the plasma exposure time, modified PTFE surfaces showed water-contact angles of 15¿58° versus 96° for unmodified PTFE. Electron spectroscopy in chemical analysis (ESCA) measurements revealed incorporation of both nitrogenand oxygen-containing groups into the PTFE surfaces, dependent on the plasma composition and exposure time. In-vitro biological evaluation of unmodified and modified PTFE surfaces showed that human endothelial cells, seeded from 20% human serum-containing culture medium, adhered well on to modified PTFE surfaces, but not on to unmodified films. Adhesion of endothelial cells on to expanded PTFE graft material (Gore-Tex) was also stimulated by plasma treatment of this substrate. On plasma-treated expanded PTFE, the adhering endothelial cells formed a monolayer, which covered the textured surface. The latter observation is important in view of the hemocompatibility of vascular grafts seeded with endothelial cells before implantation