From Single to Core-Shell Drops in Non-Confined Microfluidics

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.For many encapsulation applications such as nutrients, cells and drugs, large core-shell drops are required. Conventional confined microfluidic devices are limited to a rather small sized (< 1mm) droplets because of difficulties associated with phase separation at low flow rates. We report a microfluidic device which can produce such large range of drop sizes (~200 Am- 6 mm) with varying shell thickness (~1 Am- 1 mm) under the maximum influence of buoyancy, which has so far remained unexplored. The existing physical model for single drop formation is extended for the core-shell drop. The facile nature of working with such systems means scale up would be easy

Mercury or Mercury Free Restorations in Oral Cavity

Amalgam is basically a concoction of metals that has been used as a potent filling material in dentistry for the last 150 years. Amalgam usually consists of silver, mercury, tin and copper. Dental amalgam is a material used to fill cavities of tooth. Over the years, amalgam has become a topic of concern because it contains mercury. Mercury is a naturally occurring metal in the environment. Mercury exists as a liquid in room temperature but when heated, it becomes a gas. Flexibility of amalgam as a filling material is due Mercury. An alloy powder, a compound that is soft in nature when mixed with mercury makes it enough to mix and condense into the tooth. It hardens quickly and offers strong resistance to the forces of biting and chewing. There are studies reported on the safety of amalgam fillings. In 2005, European Union launched a comprehensive mercury strategy to reduce use of mercury. In 2008, countries like Norway and Denmark restricted the use of dental amalgam containing mercury. In 2009, this research was evaluated by U.S. Food and Drug Administration (FDA) and found no rationale to limit the use of amalgam. There are certain restorative materials that are available commercially that are mercury free in nature like Gold, Porcelain, Gallium alloys, Composite resin restoratives etc. They offer many advantages over amalgams containing mercury like: seals the dentin from future decay, reinforces remaining tooth structure, provides smooth and bonded margins, conservative and it blends naturally

An Innovative Approach of High Performance CMOS Based Current Conveyor-II for ASP Applications

The main purpose of the paper is to present a CMOS current conveyor circuit which is best suited for the implementation of low- voltage, low-power and high bandwidth circuits. To achieve the bandwidth of current transfer function the circuit can be operated for a power supply of fraction of volt which is of MHz range and a power consumption of milli-watt range. Firstly, a class A current conveyor circuit operating from a single supply of fraction of volt having a high voltage swing capability is discussed and then the same circuit is modi#64257ed to work as a class AB with a low voltage power supply in the fraction of volt range, while maintaining the same voltage swing capability. The body effect causes the threshold voltage variation and the current circuit realization is insensitive to it, which minimizes the layout area and makes both the circuits a valuable addition to the analog signal processing applications. The proposed structure has the required performance in terms of a bandwidth with level 3 CMOS technology and it operates as a linear circuit which is established with the help of 0.3 microm simulation using the PSpice software. In the field of analog signal processing this proposed current conveyor circuit has many applications. At 0.2microm the proposed circuit operates satisfactorily with high performance with the desired applications. The desired properties and the performance of the proposed circuit are confirmed by the PSpice simulation with the modeled parameters

Coronavirus peplomer charge heterogeneity

Recent advancements in viral hydrodynamics afford the calculation of the transport properties of particle suspensions from first principles, namely, from the detailed particle shapes. For coronavirus suspensions, for example, the shape can be approximated by beading (i) the spherical capsid and (ii) the radially protruding peplomers. The general rigid bead-rod theory allows us to assign Stokesian hydrodynamics to each bead. Thus, viral hydrodynamics yields the suspension rotational diffusivity, but not without first arriving at a configuration for the cationic peplomers. Prior work considered identical peplomers charged identically. However, a recent pioneering experiment uncovers remarkable peplomer size and charge heterogeneities. In this work, we use energy minimization to arrange the spikes, charged heterogeneously to obtain the coronavirus spike configuration required for its viral hydrodynamics. For this, we use the measured charge heterogeneity. We consider 20 000 randomly generated possibilities for cationic peplomers with formal charges ranging from 30 to 55. We find the configurations from energy minimization of all of these possibilities to be nearly spherically symmetric, all slightly oblate, and we report the corresponding breadth of the dimensionless rotational diffusivity, the transport property around which coronavirus cell attachment revolves.journal articl

X-ray and ion emission studies from subnanosecond laser-irradiated SiO2 aerogel foam targets

In this experiment, a comparative study of ion and X-ray emission from both a SiO2 aerogel foam and a quartz target is performed. The experiment is performed using Nd:glass laser system operated at laser energy up to 15 J with a pulse duration of 500 ps with focusable intensity of 1013–1014 W/cm2 on target. X-ray fluxes in different spectral ranges (soft and hard) are measured by using X-ray diodes covered with Al filters of thickness 5 µm (0.9–1.56 keV) and 20 µm (3.4–16 keV). A 2.5 times enhancement in soft X-ray flux (0.9–1.56 keV) and a decrease of 1.8 times in hard X rays (3.4–16 keV) for 50 mg/cc SiO2 aerogel foam is observed compared with the solid quartz. A decrease in the flux of the K-shell line emission spectrum of soft X rays is noticed in the case of the foam targets. The high-resolution K-shell spectra (He-like) of Si ions in both the cases are analyzed for the determination of plasma parameters by comparing with FLYCHK simulations. The estimated plasma temperature and density are T c = 180 eV, n e = 7 × 1020 cm−3 and T c = 190 eV, n e = 4 × 1020 cm−3 for quartz and SiO2 aerogel foam, respectively. To measure the evolution of the plasma moving away from the targets, four identical ion collectors are placed at different angles (22.5, 30, 45, and 67.5°) from target normal. The angular distribution of the thermal ions are scaled as cosnθ with respect to target normal, where n = 3.8 and 4.8 for the foam and quartz, respectively. The experimental plasma volume measured from the ion collectors and shadowgraphy images are verified by a two-dimensional Eulerian radiative–hydrodynamic simulation (POLLUX code