Adhesion and Mechanical Properties of PNIPAM Microgel Films and Their Potential Use as Switchable Cell Culture Substrates

Thermoresponsive poly(N‐isopropylacrylamide) (PNIPAM) microgel films are shown to allow controlled detachment of adsorbed cells via temperature stimuli. Cell response occurs on the timescale of several minutes, is reversible, and allows for harvesting of cells in a mild fashion. The fact that microgels are attached non‐covalently allows using them on a broad variety of (charged) surfaces and is a major advantage as compared to approaches relying on covalent attachment of active films. In the following, the microgels’ physico‐chemical parameters in the adsorbed state and their changes upon temperature variation are studied in order to gain a deeper understanding of the involved phenomena. By means of atomic force microscopy (AFM), the water content, mechanical properties, and adhesion forces of the microgel films are studied as a function of temperature. The analysis shows that these properties change drastically when crossing the critical temperature of the polymer film, which is the basis of the fast cell response upon temperature changes. Furthermore, nanoscale mechanical analysis shows that the films posses a nanoscopic gradient in mechanical properties.     

Nanocomposite Microcontainers with High Ultrasound Sensitivity

A water suspension of nanocomposite microcapsules with embedded ZnO nanoparticles in the capsule shell is reported. The microcapsule morphology is characterized by confocal microscopy, TEM, SEM, and AFM before and after ultrasound treatment. A remarkably high capsule sensitivity to ultrasound is evidenced, and it is observed to grow with increasing number of ZnO nanoparticle layers in the nanocomposite shell. This effect is correlated with the mechanical properties of microcapsules measured with AFM.     

Comparison of two quantitative proton density mapping methods in multiple sclerosis

Objective

Proton density (PD) mapping requires correction for the receive profile (RP), which is frequently performed via bias-field correction. An alternative RP-mapping method utilizes a comparison of uncorrected PD-maps and a value ρ(T1) directly derived from T1-maps via the Fatouros equation. This may be problematic in multiple sclerosis (MS), if respective parameters are only valid for healthy brain tissue. We aimed to investigate whether the alternative method yields correct PD values in MS patients.

Materials/methods

PD mapping was performed on 27 patients with relapsing-remitting MS and 27 healthy controls, utilizing both methods, yielding reference PD values (PD_ref, bias-field method) and PD_alt (alternative method).

Results

PD_alt-values closely matched PD_ref, both for patients and controls. In contrast, ρ(T1) differed by up to 3 % from PD_ref, and the voxel-wise correlation between PD_ref and ρ(T1) was reduced in a patient subgroup with a higher degree of disability. Still, discrepancies between ρ(T1) and PD_ref were almost identical across different tissue types, thus translating into a scaling factor, which cancelled out during normalization to 100 % in CSF, yielding a good agreement between PD_alt and PD_ref.

Conclusion

RP correction utilizing the auxiliary parameter ρ(T1) derived via the Fatouros equation provides accurate PD results in MS patients, in spite of discrepancies between ρ(T1) and actual PD values.

     

应对现代煤矿开采安全的主动抑爆系统

HS煤矿主动抑爆系统源于军用技术,基于智能化超高速特性,能够有效地抑制瓦斯和煤尘爆炸的破坏性形成与扩展,是煤矿防治瓦斯和煤尘技术上的重大突破.     

Application of Inhibitor‐Loaded Halloysite Nanotubes in Active Anti‐Corrosive Coatings

Halloysite particles are aluminum‐silicate hollow cylinders with a length of 0.5–1 µm, an outer diameter of ca. 50 nm and a lumen of 15 nm. These nanotubes are used for loading and sustained release of corrosion inhibitors. The inhibitor is kept inside the particles infinitely long under dry conditions. Here, halloysite nanotubes filled with anticorrosive agents are embedded into a SiO_x–ZrO_x hybrid film. An aluminum plate is dip‐coated and immersed into 0.1 M sodium chloride aqueous solution for corrosion tests. A defect in the sol–gel coating induces pitting corrosion on the metal accompanied by a strong anodic activity. The inhibitor is released within one hour from halloysite nanotubes at corrosion spots and suppresses the corrosion process. The anodic activity is successfully restrained and the protection remains for a long time period of immersion in NaCl water solution. The self‐healing effect of the sol–gel coating doped with inhibitor‐loaded halloysite nanotubes is demonstrated in situ via scanning vibrating electrode technique measurements.     

Applying genetic programming to PSB2: the next generation program synthesis benchmark suite

Genetic Programming and Evolvable Machines - For the past seven years, researchers in genetic programming and other program synthesis disciplines have used the General Program Synthesis Benchmark...