Immunoregulation of Macrophages by Controlling Winding and Unwinding of Nanohelical Ligands

Developing materials with the capability of changing their innate features can help to unravel direct interactions between cells and ligand-displaying features. This study demonstrates the grafting of magnetic nanohelices displaying cell-adhesive Arg-Gly-Asp (RGD) ligand partly to a material surface. These enable nanoscale control of rapid winding (“W”) and unwinding (“UW”) of their nongrafted portion, such as directional changes in nanohelix unwinding (lower, middle, and upper directions) by changing the position of a permanent magnet while keeping the ligand-conjugated nanohelix surface area constant. The unwinding (“UW”) setting cytocompatibility facilitates direct integrin recruitment onto the ligand-conjugated nanohelix to mediate the development of paxillin adhesion assemblies of macrophages that stimulate M2 polarization using glass and silicon substrates for in vitro and in vivo settings, respectively, at a single cell level. Real time and in vivo imaging are demonstrated that nanohelices exhibit reversible unwinding, winding, and unwinding settings, which modulate time-resolved adhesion and polarization of macrophages. It is envisaged that this remote, reversible, and cytocompatible control can help to elucidate molecular-level cell–material interactions that modulate regenerative/anti-inflammatory immune responses to implants.     

A Novel Vehicle-Based GNSS Integrity Augmentation System for Autonomous Airport Surface Operations

Autonomous vehicles equipped with integrity augmentation systems offer the potential to increase safety, efficiency and sustainability of airport ground operations. The model predictive behavior of these systems supports a timely detection of any deviations from the Required Navigation Performance (RNP), producing useful alerts for onboard mission management. Firstly, the system architecture of a Navigation and Guidance System (NGS) for autonomous airport surface vehicle operations based on Global Navigation Satellite System (GNSS) measurements is described. Subsequently, an integrity augmentation module is implemented in the NGS by modeling the key GNSS signal degradation phenomena including masking, multipath and signal attenuation. The GNSS integrity augmentation system is capable of monitoring the RNP and alerting the remote operator of the airport surface vehicle. The uniqueness of the presented system is that both caution and warning flags are produced based on prediction-avoidance and reaction-correction capabilities respectively. Additionally, the system is capable of issuing suitable steering commands to the onboard mission management system/remote ground base station operator in the event of GNSS signal degradations or losses. Multipath is modelled in detail using a ray tracing algorithm and the vehicle position error is computed as a function of relative geometry between the satellites, receiver antenna and reflectors in realistic airport operation scenarios. Additionally, the surface vehicle dynamics and reflective surfaces of buildings are modelled in order to simulate a vehicle trajectory through a typical airport airside/aprons environment. Simulation case studies are performed to validate the mathematical models developed for the integrity augmentation system and the results corroborate the suitability of the proposed system to generate useful and timely integrity flags when GNSS is used as the primary means of navigation.     

High-performance carbon electrodes for acid methanol—air fuel cells

High-performance, Teflon-bonded carbon electrodes, catalysed with highly dispersed platinum metal, have been developed for oxygen reduction in H₂SO₄. Surface-treated Vulcan XC-72 carbon has been used as the substrate material. The electrodes can be loaded with current densities of 1.1 A cm^–2 intermittently and 900 mA cm^–2 for extended periods without serious degradation. The performance of these electrodes in the presence of methanol has also been examined.     

Catalysis at Lower Temperatures

Operating heterogeneous catalytic reactions at low temperatures offers the prospects of improved selectivity, better catalyst durability and lower running costs. In practice, though, low-temperature catalysis can be unpredictable and transitory. It often arises from fragile nano-scale interactions, which can be difficult to induce,and even more difficult to measure. In trying to understand these interactions some of the long accepted tenets of catalysis are brought into question. We are seeing, however, the emergence of some generic patterns of behavior, which may ultimately allow us to custom-design durable low-temperature catalysts.     

Simulation Studies of Annealing Effect on a mc-Si Ingot for Photovoltaic Application

Silicon - A multi-crystalline silicon (mc-Si) ingot was grown by the directional solidification (DS) process for photovoltaic (PV) application. We have numerically investigated shear stress and...     

Simulation of Effect of Surface Tension in Molten Silicon During mc-Silicon Growth Process for PV Applications

Silicon - Numerical simulation of melt flow properties were performed for molten silicon for various temperature differences. The finite element method is used to compute the simulation in a 2D...     

119Sn magic angle spinning NMR of nanocrystalline SnO2

Nanocrystalline SnO2 samples of different grain sizes, prepared by inert gas condensation technique (IGCT) and chemical precipitation method and conforming to the tetragonal phase, have been studied by variable speed (3-10 kHz) 119Sn MAS NMR at 11.74 Tesla field. 119Sn solid-state NMR results show that the IGCT prepared samples have good crystallinity and phase purity compared to the samples prepared by the chemical method. The determination of 119Sn chemical shielding parameters (delta iso, delta delta and eta) from slow MAS spectra shows that the 119Sn isotropic chemical shift (delta iso) is strongly influenced at smaller grain sizes, attributable to the change in the O2- local symmetry for the surface 119Sn ions at smaller grain sizes. The observed line widths in MAS spectra are significantly larger than the life-time broadening due to spin-lattice (T1) and spin-spin (T2) relaxation. The 119Sn MAS NMR spectra are thus inhomogeneously broadened by a distribution of isotropic chemical shifts, the line broadening increasing with decrease in grain size.     

Green synthesis of TiO2 nanoparticles prepared from Phyllanthus niruri leaf extract for dye adsorption and their isotherm and kinetic studies

Herein, the green synthesis of TiO₂ nanoparticles using Phyllanthus niruri leaf extract was accomplished by the sol‐gel method. The structure and particle size of the synthesised TiO₂ nanoparticles were characterised by X‐ray diffraction (XRD) analysis and the size was found to be 20 nm. The Fourier‐transform infrared spectra determined the existence of carboxyl and hydroxyl functional groups. The images from SEM analysis recommended a porous and heterogeneous surface. The methyl orange (MO) dye removal was examined using different parameters such as pH, time, dose, temperature and dye concentration. Maximum dye elimination percentage was achieved at pH 6.0 and 0.02 g as the optimum adsorbent dose. The kinetic analysis suggested that the pseudo‐second‐order kinetic model finely defines adsorption dynamics. Langmuir adsorption isotherm studies revealed endothermic monolayer adsorption of the methyl Orange dye. The negative value of ∆G° and positive value of ∆H° showed the spontaneous and endothermic adsorption method.     

Correlating Molecular Structure to the Behavior of Linear Styrene–Butadiene Viscosity Modifiers

The effect of linear styrene–butadiene polymer structure on the temperature–viscosity behavior of model polymer-base oil solutions is investigated using molecular dynamics simulations. Simulations of alternating, random, and block styrene–butadiene polymers in a dodecane solvent are used to calculate viscosity at 40 and 100 °C, reference temperatures for characterizing their function as viscosity modifiers. Mechanisms underlying this function are explored by quantifying the radius of gyration and intramolecular interactions of the polymers at the same reference temperatures. The block styrene–butadiene configuration exhibits the least change in viscosity with temperature, characteristic of a good viscosity modifier or viscosity index improver, and the behavior is correlated to the ability of this structure to form smaller coils with more intramolecular interactions at lower temperatures and then expand as temperature is increased. The results indicate that there is a correlation between styrene–butadiene polymer structure, additive function, and the mechanisms underlying that function.     

Improved method for development of parsimonious orthonormal basis filter models

One of the major advantages of orthonormal basis filter (OBF) models is that they are parsimonious in parameters. However, this is true only if appropriate type of filter and reasonably accurate dominant poles of the system are used in developing the model. An arbitrary choice of filter type and poles may lead to non-parsimonious model. While the selection of the type of filter may be simple if the damping characteristics of the system are known, finding good estimates of the dominant pole(s) of the system is not a trivial task. Another important advantage of OBF model is the fact that time delays can be easily estimated and incorporated into the model. Currently, time delay of the system is estimated from the step response of the OBF model using the tangent method. While this method is effective in estimating the time delay of systems that can be accurately modeled by first order plus time delay (FOPTD) models, the accuracy is low for systems with second- and higher-order dynamics. In this paper, a scheme is proposed that will result in parsimonious OBF model and a better estimate of time delay starting from an arbitrary set of poles.