Altered Surface Features Research Articles

Biodegradable nanoparticles bearing amine groups as a strategy to alter surface features, biological identity and accumulation in a lung metastasis model.

Polymer-based nanoparticles (NPs) with a cationic charge have emerged recently as a potent nanotool due to their unique ability to penetrate deeply inside tumor tissue and to interact preferentially with the plasma membrane of cancer cells. In this paper, we propose a general strategy to obtain biodegradable cationic NPs of poly(ε-caprolactone) (PCL) based on an amine terminated PCL (NH2-PCL4.2k) or its mixture with monomethoxypoly(ethylene glycol)-PCL (mPEG1k-PCL4k). Positively-charged NPs were obtained, switching to net negative values through adsorption of low molecular weight hyaluronan. NPs exposing both amine and PEG groups on the surface showed a larger fixed aqueous layer thickness as compared to fully PEGylated NPs, suggesting that PEG conformation/localization is affected by the presence of amino groups. The stability of the positively-charged NPs was affected by the presence of ions, while interaction with the human plasma protein pool indicated time-dependent protein corona formation imparting an overall negative charge. NP-induced haemolysis was low, while cytotoxicity against A549 and Calu-3 lung cancer cell lines was cell-specific as well as dose and time-dependent. Finally, the presence of amino groups greatly changed the in vivo biodistribution of the NPs in tumor-bearing mice (lung colonization of B16F10 cancer cells) allowing the amine/PEGylated NPs to accumulate mainly at the target organ. Overall, this study demonstrates that NPs with a mixed amine/PEGylated surface exhibit a peculiar biological identity that alters their interaction with the bioenvironment and are thus worthy of further investigation in the delivery of chemotherapeutics.

Correction: Biodegradable nanoparticles bearing amine groups as a strategy to alter surface features, biological identity and accumulation in a lung metastasis model.

Correction for 'Biodegradable nanoparticles bearing amine groups as a strategy to alter surface features, biological identity and accumulation in a lung metastasis model' by Diletta Esposito et al., J. Mater. Chem. B, 2018, 6, 5922-5930.

Measurement of Surface Changes in a Scaled-Down Landslide Model Using High-Speed Stereo Image Sequences

Construction of scaled-down landslide models is an important means for landslide study. The objective of this study is to develop an innovative non-contact photogrammetric system to meet the challenge for monitoring the fast surface deformation of a laboratory-simulated landslide, which can detect pre-failure events and the final failure, provide sectional and overall surface deformation patterns, and generate speed maps during the rapid slope failure. We proposed an event detector based on altered surface features in the slower slrc (single-lens-reflex camera) image sequence to detect pre-failure events, while a combined analysis tool used the surface velocity fields and deformation areas based on fast hscs (high-speed stereocamera system) stereo image sequences to reveal fast-changing landslide behavior during the short final failure. The introduced surface change detector uses the percentage of sliding block areas, percentage of changed features, and average speeds. It successfully detected four pre-failure local collapse events and the final slope failure; the extent of surface changes reached its maximum to accumulate energy 1.5seconds before the failure when the average speed of changed features achieved its peak of 0.8m/s. The developed system achieved a position accuracy of 3.8mm and a speed accuracy of 0.11m/s. The analysis result demonstrated a time period of 66minutes before the failure which is confirmed by significant signals from both imaging and contact sensors and is important for landslide early warning. A field implementation scheme in western China will be designed and realized in the near future.

Measurement of Surface Changes in a Scaled-Down Landslide Model Using High-Speed Stereo Image Sequences

Construction of scaled-down landslide models is an important means for landslide study. The objective of this study is to develop an innovative non-contact photogrammetric system to meet the challenge for monitoring the fast surface deformation of a laboratory-simulated landslide, which can detect pre-failure events and the final failure, provide sectional and overall surface deformation patterns, and generate speed maps during the rapid slope failure. We proposed an event detector based on altered surface features in the slower SLRC (single-lensreflex camera) image sequence to detect pre-failure events, while a combined analysis tool used the surface velocity fields and deformation areas based on fast HSCS (high-speed stereocamera system) stereo image sequences to reveal fast-changing landslide behavior during the short final failure. The introduced surface change detector uses the percentage of sliding block areas, percentage of changed features, and average speeds. It successfully detected four pre-failure local collapse events and the final slope failure; the extent of surface changes reached its maximum to accumulate energy 1.5 seconds before the failure when the average speed of changed features achieved its peak of 0.8 m/s. The developed system achieved a position accuracy of 3.8 mm and a speed accuracy of 0.11 m/s. The analysis result demonstrated a time period of 66 minutes before the failure which is confirmed by significant signals from both imaging and contact sensors and is important for landslide early warning. A field implementation scheme in western China will be designed and realized in the near future.

Microstructural and hardness investigation of tool steel D2 processed by laser surface melting and alloying

Several techniques can be used to improve surface properties of metals. These can involve changes on the surface chemical composition such as alloying or on the surface microstructure, such as hardening. In the present work, melting of the surface by a 9 kW CO2 CW laser of wavelength 10.6 μm was used to alter surface features of D2 tool steel. Carbon powder and nitrogen gas were used as sources of alloying elements during laser processing. The effect of various laser parameters (power and speed) on the microstructure and hardness of D2 tool steel was investigated. Laser powers from 1 to 8 kW and laser speeds from 5 to 15 mm/s were employed. It was found that as the laser power increases, the hardness of the melted zone decreases while that of the heat-affected zone increases. On the other hand, the depth of both of melted and heat-affected zones increases with power.

Incorporating stimulus-responsive character into filamentous virus assemblies

Controlling interactions between building blocks, in either guided- or self-assemblies, is becoming increasingly important for the creation of functional materials. We have focused our attention on the well-known model assembly, the filamentous bacteriophage, where our strategy is to selectively alter surface features by focusing on spatially distinct capsid proteins. Towards introducing stimulus-responsive behavior in these flexible, rod-like particles, we have introduced elastin-like polypeptide (ELP) motifs of isoleucine and tyrosine "guest" residues by recombinant DNA methods. Our hypothesis is that modification of the major coat capsid protein would be greatly amplified by the 2700 copies per particle. Characterization of ELP-phage particles was carried out by microbiological assays, zeta potential, dynamic light scattering, and calorimetry. Bacteria producing ELP-phage particles grow more slowly and surprisingly, ELP-modified phages display a significant reduction in viral infectivity. For the lengths of ELP inserts studied, modified phages do not aggregate from solution as monitored by DLS. However, the hydrodynamic size of the phages depends on the details of the ELP motif. Zeta potential measurements reveal the particles are electrostatically stabilized, and this contributes in part to the energetic barrier against aggregation. Preliminary calorimetric data indicate subtle thermal transitions in the range 35-45 degrees C, suggesting that the ELP motif may collapse without triggering macroscopic aggregation. The results are consistent with the classical picture of critical solution phenomena at low concentrations, where to drive phase separation, solvent quality must be increasingly poor. Apart from being model systems to study basic questions of self-assembly, extending these modular systems is likely to result in improved understanding and control over self-assembly in various applications.

Microstructural changes due to laser surface melting of an AISI 304 stainless steel

Several techniques can be used to improve surface properties. These can involve changes on the surface chemical composition (such as alloying and surface welding processes) or on the surface microstructure, such as hardening and melting. In the present work surface melting with a 3kW CO2 cw laser was done to alter surface features of an AISI 304 stainless steel. Microstructure characterisation was done by optical and scanning electron microscopy. Vickers and Knoop microhardness tests evaluated mechanical features after surface melting. Phase transformation during rapid solidification is analysed and discussed.

Target modification in the excimer laser deposition of YBa2Cu3O7−x thin films

Under conditions used for pulsed laser deposition (308 nm, 20 ns, 2–8 J/cm2) of Y-Ba-Cu-O superconducting thin films, we have measured a pronounced decrease in deposition rate with cumulative laser exposure of the target. This decay in rate is accompanied by evolution on the target surface of microscopic columnar structures, having yttrium-enriched surfaces, which are aligned in the direction of the incident laser beam (45°). Neither the vapor plume direction nor film stoichiometry is affected by the presence of these oriented, chemically altered surface features.

Techniques for assessing the vulnerability and repair capacity of human skin in vivo.

Techniques have been developed for studying age-associated changes in human skin, including its vulnerability to external insults and its capacity for healing. Possible application of these methods for studying the effects of repeated mechanical trauma to the skin of workers is discussed. The methods include procedures for inflicting standardized superficial wounds and nonintrusive techniques for measuring damage, rate of skin repair via measurement of transepidermal water loss, and characterization of altered surface features using image analyses. These approaches have the great advantage of allowing quantification.