Self‐Propelled Activated Carbon Janus Micromotors for Efficient Water Purification

Self‐propelled activated carbon‐based Janus particle micromotors that display efficient locomotion in environmental matrices and offer effective ‘on‐the‐fly’ removal of wide range of organic and inorganic pollutants are described. The new bubble‐propelled activated carbon Janus micromotors rely on the asymmetric deposition of a catalytic Pt patch on the surface of activated carbon microspheres. The rough surface of the activated carbon microsphere substrate results in a microporous Pt structure to provide a highly catalytic layer, which leads to an effective bubble evolution and propulsion at remarkable speeds of over 500 μm/s. Such coupling of the high adsorption capacity of carbon nanoadsorbents with the rapid movement of these catalytic Janus micromotors, along with the corresponding fluid dynamics and mixing, results in a highly efficient moving adsorption platform and a greatly accelerated water purification. The adsorption kinetics and adsorption isotherms have been investigated. The remarkable decontamination efficiency of self‐propelled activated carbon‐based Janus micromotors is illustrated towards the rapid removal of heavy metals, nitroaromatic explosives, organophosphorous nerve agents and azo‐dye compounds, indicating considerable promise for diverse environmental, defense, and public health applications.     

Surface Chemistry of Vitamin: Pyridoxal 5′‐Phosphate (Vitamin B6) as a Multifunctional Compound for Surface Functionalization

Vitamins are non‐toxic compounds that perform a variety of biological functions and also available in a large quantity. Other than the usage as food supplements, few attempts have been made to use them as functional materials. In this study, we report that vitamin B6, pyridoxal 5′‐phosphate (PLP), is a multi‐functional molecule for oxide surface chemistry. PLP‐immobilized surfaces exhibit superhydrophilicity and even hemophilicity, enhancing proliferation, migration, and differentiation of mammalian cells. Unlike existing molecules used so far in surface modification, PLP has an intrinsic chemical reactivity toward biomacromolecules due to the presence of the aldehyde group. In fact, RGD peptide is covalently tethered onto PLP surfaces directly in one step without any chemical activation. Furthermore, PLP‐functionalized implant device showed rapid bone healing. As vitamin B6 is a FDA approved molecule for human usage, the surface chemistry of vitamin B6 potentially allows a fast route for surface functionalized medical devices into clinic.     

Evaluation of routing flexibility of a flexible manufacturing system using simulation modelling and analysis

Routing flexibility is a major contributor of the flexibility of a flexible manufacturing system (FMS). The present paper focuses on the evaluation of the routing flexibility of an FMS with the dynamic arrival of part types for processing in the system. A typical FMS configuration is chosen for detailed study and analysis. The system is set at five different levels of routing flexibility. Operations of part types can be processed on alternative machines depending upon the level of routing flexibility present in the system. Two cases have been considered with respect to the processing times of operations on alternative machines. A discrete-event simulation model has been developed to describe the operation of the chosen FMS. The performance of the system under various levels of routing flexibility is analyzed using measures such as mean flow time, mean tardiness, percentage of tardy parts, mean utilisation of machines, mean utilisation of automatic-guided vehicles, and mean queue length at machines. The routing flexibility for producing individual part types has been evaluated in terms of measures such as routing efficiency, routing versatility, routing variety and routing flexibility. The routing flexibility of the system has been evaluated using these measures. The flexibility levels are ranked based on the routing flexibility measure for the system. The ranking thus obtained has been validated with that derived using fuzzy logic approach.     

Turbulent transport coefficients in supersonic flow

Hypersonic ramjets employing supersonic combustion of hydrogen fuel have attractive potentialities for future aircraft or launching systems. The object of the present work ^§ was to study quantitatively the effects of fuel injection parameters on the mixing of gaseous hydrogen fuel with a supersonic air stream confined within a cylindrical duct, to provide some of the fundamental background needed for the design of supersonic combustors for high-performance engines. Hydrogen was injected at sonic velocities into Mach 2 and Mach 3 air streams, at overall equivalence ratios of 0.17 to 0.50, in both radial and axial (downstream) directions from circumferential wall slots. Results showed that considerably better mixing occurred in the case of radial injection, although the decrease in stagnation pressure also was greater for this case.

The eddy diffusivity of mass, E_d (turbulent diffusion coefficient) and radial velocity, , were determined by differentiating experimental concentration, velocity and density profiles, obtained at various axial distances from the injection station. For the radial injection case, with a 1-in i.d. test section, a simple model in which E_d varied only in the radial direction and varied only in the axial direction, allowed reasonable correlation of the experimental results. The validity of the trends obtained in E_d and were checked by numerical integration of the diffusion equation, and simultaneous solution of the diffusion and momentum equations; computed profiles agreed reasonably well with downstream experimental concentration and velocity profiles. A method for solving turbulent mixing problems by simultaneous solution of the diffusion, momentum and energy equations is presented.     

Synthesis of pure anatase TiO2 nanocrystals in SiO2 host and the determination of crystal planes by ImageJ

Anatase TiO₂ nanocrystals in the TiO₂- SiO₂ matrix were prepared by the ultra hydroylsis sol-gel route. The samples were heat treated at 350 °C and 500 °C. The structural analyses of the samples were carried out using X-ray diffraction technique, Raman spectroscopy and Transmission electron microscopy. The size of the nanocrystals from the XRD spectra (8.3 nm) and TEM (5-8 nm) is well in agreement. The spacing for the crystal planes was also determined using the ImageJ program. The Raman peaks further confirmed the formation of only the anatase phase within the matrix.     

X-ray diffraction from intact tau aggregates in human brain tissue

We describe an instrument to record x-ray diffraction patterns from diseased regions of human brain tissue by combining an in-line visible light fluorescence microscope with an x-ray diffraction microprobe. We use thiazine red fluorescence to specifically label and detect the filamentous tau protein pathology associated with Pick's disease, as several labs have done previously. We demonstrate that thiazine red-enhanced regions within the tissue show periodic structure in x-ray diffraction that is not observed in healthy tissue. One observed periodicity (4.2 ?) is characteristic of cross-beta sheet structure, consistent with previous results from powder diffraction studies performed on purified, dried tau protein.