Μm Radius Research Articles

Fundamentals of the Local Anodic Oxidation of Graphene for Scalable Applications

Using a novel instrument previously reported by our group [1], we have been able to perform Local Anodic Oxidation (LAO) over monolayer graphene to create unprecedented large areas (larger than mm2) of single layer Graphene Oxide (GO) with any shape and in a very short time (a few minutes). Our instrument is equipped with three electromechanical steppers with 0.05 µm accuracy and 1 µm precision, and each stepper with a linear piezoactuator. It operates at speeds up to 15 mm/s, and includes a steel/Ni spring probe of typically 6 µm radius to work in tapping or contact mode. The equipment is provided with a humidity control system that allows maintaining a stable Relative Humidity (RH) environment, together with a system of supply and electrical monitoring. Thus, electrical signal coming from the tip-sample interaction is continuously monitored (by means of a high speed oscilloscope). When the tip approaches to graphene on a wet atmosphere (RH higher than 40%), it is commonly accepted that a water bridge is created between them. When a negative bias is applied to the tip respect to the grounded graphene (in our case we operate between 20V - 40 V), the LAO phenomena takes place [2] (Fig. 1a). The process firstly consists on electrical water ionization in H+ and OH- ions. Hydroxyl anions are then conducted to the graphene surface, which is thus oxidized. Within a specific RH range, the oxide patterns created show a good reproducibility and regular shape (Fig. 1b). Controlling the movement of the tip, we can draw the desired patterns over the graphene or any other 2D-substrate (Fig. 1c). We have extensively studied and optimized the influence of the experimental variables affecting the process, like applied bias, contact time or relative humidity. This LAO procedure is so a very powerful tool for the fabrication of electrical devices. Also, the possibility of chemical functionalization of GO allow us to design a large variety of utilities like (bio)chemical sensors, supported catalysts, etc. In addition, we have been able to record the electrochemical trace generated during the oxidation reaction of graphene. To our knowledge, it is the first time these records have been reported. Moreover, based on these data, we have formulated a theoretical model based just on classical first principles that predicts the behavior of the LAO process over graphene. This model shows a very accurate fit for the dependence of the oxide pattern expansion with the applied voltage (Fig. 2a), with the contact time (Fig. 2b), and also for the evolution of the recorded transient electric current (Fig. 2c). This model reveals very relevant information about the processes governing LAO. First, at the beginning (< 20 ms), most of the total current I(t) passing through the tip-substrate junction does not come from the electrochemical reaction but from residual conductance of the non-oxidized graphene. We call this component drift current, IT(t). Second, for longer times (>200 ms), the total current becomes dominated just by the electrochemical reaction, and the drift component almost vanishes. We call this component electrochemical current, IEC(t) (Fig. 2c). Third, the process is mainly driven by the electric field increase at the edge of the pattern. And fourth, the GO generated has a very high oxidation degree. This work opens new promising fields for development of extensive fabrication methods, technical applications and the study of anodic oxidation processes of conducting and any 2d material at large scales.

Exogenous Cytokine-Free Differentiation of Human Pluripotent Stem Cells into Classical Brown Adipocytes.

We previously established a method for a directed differentiation of human pluripotent stem cells into classical brown adipocytes (BA) by forming aggregates via massive floating culture in the presence of a specific cytokine cocktail. However, use of recombinant cytokines requires significant cost. Moreover, an enforced differentiation by exogenously added cytokines may amend skewed differentiation propensity of patient’s pluripotent stem cells, providing unsatisfactory disease models. Therefore, an exogenous cytokine-free method, where cytokines required for differentiation are provided in an auto/paracrine manner mimicking natural developmental process, is beneficial. Here we show that, if human pluripotent stem cells are cultured as size-controlled spheroids (100–120 µm radius, 2000–2500 cells/spheroid) in a mutually segregated manner with half-change of the medium every other day, they differentiate into classical BA via an authentic MYF5-positive myoblast route in the absence of exogenous cytokines. Differentiated BA exerted thermogenic activity in transplanted mice in response to beta-adrenergic receptor agonist stimuli. The cytokine-free differentiation method has further advantages in exploring BATokines, BA-derived physiologically active substances. Indeed, we have found that BA produces an unknown small (<1000 Da), highly hydrophilic molecule that augments insulin secretion from pancreatic beta cells. Our upgraded technique will contribute to an advancement of stem cell study for diverse purposes.

Closed system behaviour of argon in osumilite records protracted high‐Tmetamorphism within the Rogaland–Vest Agder Sector, Norway

AbstractHere, we present results of the first40Ar/39Ar dating of osumilite, a high‐Tmineral that occurs in some volcanic and high‐grade metamorphic rocks. The metamorphic osumilite studied here is from a metapelitic rock within the Rogaland–Vest Agder Sector, Norway, an area that experienced regional granulite facies metamorphism and subsequent contact metamorphism between 1,100 Ma and 850 Ma. The large grain size (~1 cm) of osumilite in the studied rock, which preserves a nominally anhydrous assemblage, increases the potential for large portions of individual grains to have remained essentially unaffected by the effects of diffusive argon loss, potentially preserving prograde ages. Step‐heating diffusion experiments yielded a maximum activation energy of ~461 kJ/mol and a pre‐exponential factor of ~8.34 × 108 cm2/s for Ar diffusion in osumilite. These parameters correspond to a relatively high closure temperature of ~620°C for a cooling rate of 10°C/Ma in an osumilite crystal with a 175 µm radius. Fragments of osumilite separated from the sample preserve a range of ages betweenc. 1,070 and 860 Ma. The oldest ages are inferred to date the growth of coarse‐grained osumilite during prograde granulite facies regional metamorphism, which pre‐date contact metamorphism that has historically been ascribed to the growth of osumilite in the region. The majority of fragments record ages betweenc. 920 and 860 Ma, inferred to reflect the growth of osumilite and/or diffusive argon loss during contact metamorphism. The retention of old40Ar/39Ar dates was facilitated by the low diffusivity of Ar in osumilite (i.e. a closed system), large grain sizes, and anhydrous metamorphic conditions. The ability to date osumilite with the40Ar/39Ar method provides a valuable new thermochronometer that may constrain the timing and duration of high‐Tmagmatic and metamorphic events.

C/2010 U3 (Boattini): A Bizarre Comet Active at Record Heliocentric Distance

Abstract We present a photometric and dynamical study of comet C/2010 U3 (Boattini), which was seen active in prediscovery data as early as 2005 November at a new inbound record heliocentric distance of r H = 25.8 au. Two outburst events around 2009 and 2017 were observed. The coma and tail of the comet consist of dust grains of ∼10 μm in radius, ejected protractedly at speeds ≲50 m s−1 near the subsolar point, and are subjected to the Lorentz force, solar gravitation, and radiation pressure force all together. The prolonged activity indicates that sublimation of supervolatiles (e.g., CO, CO2) is at play, causing a net mass-loss rate ≳1 kg s−1. To sustain the mass loss, the nucleus radius has to be ≳0.1 km. The color of the cometary dust, similar to other long-period comets, is redder than the solar colors, but we also observed potential color variations when the comet was at 10 &lt; r H &lt; 15 au, concurrent with the onset of crystallization of amorphous water ice, if at all. Using publicly available and our refined astrometric measurements, we estimated the precise trajectory of the comet and propagated it backward to its previous perihelion. We found that the comet visited the planetary region 1.96 ± 0.04 Myr ago, with barycentric perihelion distance q = 8.364 ± 0.004 au. Thus, C/2010 U3 (Boattini) is almost certainly a dynamically old comet from the Oort cloud, and the observed activity cannot be caused by retained heat from the previous apparition.

Long Slender Piezo-Resistive Silicon Microprobes for Fast Measurements of Roughness and Mechanical Properties inside Micro-Holes with Diameters below 100 µm

During the past decade, piezo-resistive cantilever type silicon microprobes for high-speed roughness measurements inside high-aspect-ratio microstructures, like injection nozzles or critical gas nozzles have been developed. This article summarizes their metrological properties for fast roughness and shape measurements including noise, damping, tip form, tip wear, and probing forces and presents the first results on the measurement of mechanical surface parameters. Due to the small mass of the cantilever microprobes, roughness measurements at very high traverse speeds up to 15 mm/s are possible. At these high scanning speeds, considerable wear of the integrated silicon tips was observed in the past. In this paper, a new tip-testing artefact with rectangular grooves of different width was used to measure this wear and to measure the tip shape, which is needed for morphological filtering of the measured profiles and, thus, for accurate form measurements. To reduce tip wear, the integrated silicon tips were replaced by low-wear spherical diamond tips of a 2 µm radius. Currently, a compact microprobe device with an integrated feed-unit is being developed for high-speed roughness measurements on manufacturing machines. First measurements on sinusoidal artefacts were carried out successfully. Moreover, the first measurements of the elastic modulus of a polymer surface applying the contact resonance measurement principle are presented, which indicates the high potential of these microprobes for simultaneous high-speed roughness and mechanical parameter measurements.

Surface Tensions of Picoliter Droplets with Sub-Millisecond Surface Age.

Aerosols are key components of the atmosphere and play important roles in many industrial processes. Because aerosol particles have high surface-to-volume ratios, their surface properties are especially important. However, direct measurement of the surface properties of aerosol particles is challenging. In this work, we describe an approach to measure the surface tension of picoliter volume droplets with surface age <1 ms by resolving their dynamic oscillations in shape immediately after ejection from a microdroplet dispenser. Droplet shape oscillations are monitored by highly time-resolved (500 ns) stroboscopic imaging, and droplet surface tension is accurately retrieved across a wide range of droplet sizes (10-25 μm radius) and surface ages (down to ∼100 μs). The approach is validated for droplets containing sodium chloride, glutaric acid, and water, which all show no variation in surface tension with surface age. Experimental results from the microdroplet dispenser approach are compared to complementary surface tension measurements of 5-10 μm radius droplets with aged surfaces using a holographic optical tweezers approach and predictions of surface tension using a statistical thermodynamic model. These approaches combined will allow investigation of droplet surface tension across a wide range of droplet sizes, compositions, and surface ages.

Damage controlled by brittle particles crush in AA7075-T6 beneath spherical indenter

The distribution of damage controlled by brittle particles crush in AA7075-T6 beneath spherical indenter was obtained experimentally and predicted analytically. Micro hardness tests were conducted on the vertical sections across the indentation impression and by comparing it with the estimated ideal micro hardness, the damage beneath spherical indenter can be quantified. In the present study, for a spherical indenter with 794 μm radius and a 117 μm penetration, maximum damage is 0.29, locating in the middle of the contact arc. The damage along path 1, which is right below the indentation impression, has generally smaller damage and the path 3, which is below the middle of the contact arc, has more extensive damage. Through a model which can describe the damage controlled by second phase particles crush, a modified expanding cavity model (ECM) coupling with the Ramberg-Osgood stress-strain relation was applied to predict the distribution of damage in spherical indentation deformation. By comparing with the experimental results, it proved that the method could give a prediction with reasonable accuracy.

Study of the effects of source type and magnetic field on the spatial distribution of positron annihilation events in PET/MRI applications

In this paper, we investigate the spatial distribution of positron annihilation events in PET//MRI systems. A spherical source ranging from 0mm to 10mm in radius was placed in water to represent the tumor region. The magnetic field strength was adjusted from 0T to 30T, and three positron nuclides, 18F , 11C , 68Ga , were used. The positron annihilation distribution was compared with the nuclide distribution (to represent pathological tumor), and the differences in these distribution with and without the magnetic field were evaluated. The compression effect of magnetic field on positron distribution was also investigated. For 11C and 68Ga sources with radioactive source size (rs) of less than 4 mm and 6 mm, respectively, it was found that the critical radius (d of the sphere, which contains 90% annihilated positrons, was significantly larger than its original radioactive source size rs. When the magnetic field was increased to 15T, it was found that the greatest compression occurred with a 2 mm 68Ga source (which also exhibited the greatest contraction in volume V1 although this was larger than the source volume V . Our proposed model of the volume source indicates that the positron distribution deviates greatly from the nuclide distribution for high-energy positron emitted in small source.

Target strength measurements of spherical and wobbly bubbles

Methane gas bubbles released from the seafloor transport gas upwards through the water column and in some cases even to the atmosphere. Researchers exploit the large acoustic impedance contrast between the gas within the bubble and the surrounding water to acoustically estimate the flux of methane in the ocean. Flux estimation employs the use of analytical acoustic scattering models to convert acoustic backscatter measurements of gas bubbles to size estimates. However, these models assume that bubbles are both spherical and that their radius is much smaller than the acoustic wavelength (ka « 1). Typically, bubbles in the ocean range from 1 to 5 mm in radius are non-spherical in shape and are observed for ka values that are greater than 0.1. A controlled shallow water tank (<6 m) experiment was conducted to assess the uncertainty associated with using analytical models that assume bubbles are spherical and that ka values are much smaller than one. Small, spherical and large, wobbly gas bubbles (radii ranging from 0.7 to 4.5 mm) were ensonified over a broad range of frequencies (10–250 kHz) in order to observe ka values from 0.1 to 5.

Electric and Magnetic Hotspots via Hollow InSb Microspheres for Enhanced Terahertz Spectroscopy

We study electric and magnetic hotspots in the gap between hollow InSb microspheres forming dimers and trimers. The outer radius, core volume fraction, distance, and temperature of the microspheres can be chosen to achieve field enhancement at a certain frequency corresponding to the transition between energy levels of a molecule placed in the gap. For example, utilizing 80 μm radius spheres at a gap of 2 μm held at a temperature of 295 K, allow electric field intensity enhancements of 10–2880 and magnetic field intensity enhancements of 3–61 in the frequency window 0.35–1.50 THz. The core volume fraction and the ambient temperature affect the enhancements, particularly in the frequency window 1.5–2 THz. Electric and magnetic hotspots are promising for THz absorption and circular dichroism spectroscopy.

Assessing image artifacts from radiotherapy electromagnetic transponders with metal-artifact reduction imaging

Image artifacts due to 14 gauge radiotherapy electromagnetic (EM) transponders were assessed on conventional spin echo images, and corrected using metal artifact reduction techniques: high bandwidth, view angle tilting (VAT), and slice encoding for metal artifact correction (SEMAC). Large areas of signal loss and/or pile-up were produced in an area extending up to 15.3 mm in radius for 14G transponders in standard imaging. Using high bandwidth imaging with VAT, in-plane artifact sizes were reduced by up to 35%. SEMAC did not significantly reduce in-plane or through plane artifact size for axially oriented images, but was effective in reducing through-plane artifacts for sagittal images. Using the experimental data, magnetic field maps were simulated so that the magnetic susceptibility of the transponder could be estimated and slice profiles could be visualized. Due to the large susceptibilities involved, current correction techniques are unable to fully correct artifacts due to EM transponders and significant areas of signal loss and distortion remain. Care should be taken when planning MRI following EM transponder implantation.

ECG Imaging to Detect the Site of Ventricular Ischemia Using Torso Electrodes: A Computational Study.

Electrocardiography provides some information useful for ischemic diagnosis. However, more recently there has been substantial growth in the area of ECG imaging, which by solving the inverse problem of electrocardiography aims to produce high-resolution mapping of the electrical and magnetic dynamics of the heart. Most inverse studies use the full resolution of the body surface potential (BSP) to reconstruct the epicardial potentials, however using a limited number of torso electrodes to interpolate the BSP is more clinically relevant and has an important effect on the reconstruction which must be quantified. A circular ischemic lesion on the right ventricle lateral wall 27 mm in radius is reconstructed using three Tikhonov methods along with 6 different electrode configurations ranging from 32 leads to 1,024 leads. The 2nd order Tikhonov solution performed the most accurately (~80% lesion identified) followed by the 1st (~50% lesion identified) and then the 0 order Tikhonov solution performed the worst with a maximum of ~30% lesion identified regardless of how many leads were used. With an increasing number of leads the solution produces less error, and the error becomes more localised around the lesion for all three regularisation methods. In noisy conditions, the relative performance gap of the 1st and 2nd order Tikhonov solutions was reduced, and determining an accurate regularisation parameter became relatively more difficult. Lesions located on the left ventricle walls were also able to be identified but comparatively to the right ventricle lateral wall performed marginally worse with lesions located on the interventricular septum being able to be indicated by the reconstructions but not successfully identified against the error. The quality of reconstruction was found to decrease as the lesion radius decreased, with a lesion radius of <20 mm becoming difficult to correctly identify against the error even when using >512 torso electrodes.

Integration of Molybdenum-Doped, Hydrogen-Annealed BiVO4 with Silicon Microwires for Photoelectrochemical Applications.

H-BiVO4–x:Mo was successfully deposited on microwire-structured silicon substrates, using indium tin oxide (ITO) as an interlayer and BiOI prepared by electrodeposition as precursor. Electrodeposition of BiOI, induced by the electrochemical reduction of p-benzoquinone, appeared to proceed through three stages, being nucleation of particles at the base and bottom of the microwire arrays, followed by rapid (homogeneous) growth, and termination by increasing interfacial resistances. Variations in charge density and morphology as a function of spacing of the microwires are explained by (a) variations in mass transfer limitations, most likely associated with the electrochemical reduction of p-benzoquinone, and (b) inhomogeneity in ITO deposition. Unexpectedly, H-BiVO4–x:Mo on microwire substrates (4 μm radius, 4 to 20 μm spacing, and 5 to 16 μm length) underperformed compared to H-BiVO4–x:Mo on flat surfaces in photocatalytic tests employing sulfite (SO32–) oxidation in a KPi buffer solution at pH 7.0. While we cannot exclude optical effects, or differences in material properties on the nanoscale, we predominantly attribute this to detrimental diffusion limitations of the redox species within the internal volume of the microwire arrays, in agreement with existing literature and the observations regarding the electrodeposition of BiOI. Our results may assist in developing high-efficiency PEC devices.

Experimental investigation on silica dust lofting due to charging within micro-cavities and surface electric field in the vacuum chamber

The charged dust particles can be mobilized electrostatically by the repulsion between the adjacent grains and the surface electric field due to the incoming electron current and the charge accumulation within the micro-cavities. In this study, the experimental results of the initial vertical launching velocities and the maximum dust heights are compared with the estimated values for the lofted spherical dust grains by the patch surface charging equations. Silica particles with the sizes between <6 and 45 µm in radius are loaded on a graphite plate, and they are exposed to the electron beam with 450 eV energy under 4 × 10−3 Pa vacuum chamber pressure. During the first set of the experiments, the dust samples are tested without an initial compression process and an additional horizontal electric field. Second, the dust samples are compressed by two different weights in order to increase the packing density under approximately 780.7 Pa and 3780 Pa. Finally, the dust grains are placed between the two parallel aluminum plates to apply approximately 2000 V/m and 4800 V/m horizontal electric field. A high-speed camera is used to record the transportation of the dust grains together with a microscopic telescope, and the results point out that the patch surface dust-charging model estimations are in agreement with the first experiments. On the other hand, the dust particles from the compressed samples are lofted with higher velocities than the estimations, and the number of the dust lofting observations decreases significantly, which demonstrates the importance of the micro-cavities and the increased charging requirement to overcome the contact forces. When the horizontal electric field is present, the initial vertical launching velocities are measured to be lower than the other experiments, which can be attributed to the decreased charging requirement for the dust lofting as a result of inter-particle collisions and rolling motion. According to the experimental results, the electrostatic dust transportation can be controlled not only by the ambient plasma and the solar irradiation on the airless planetary bodies, but also by the surface properties such as the contact surfaces between the dust grains, the number of the micro-cavities related to the packing density, and the presence of the horizontal electric field contributing to the external forces by other particle motions.

Mechanism of Flotation of Metallic Droplets in Oxide Melts

The flotation of droplets in liquids is a frequent phenomenon. For example, flotation is the basis of the removal of liquid nonmetallic inclusions from steel. However, the mechanism of this phenomenon is still poorly understood. The mechanism of flotation of metallic droplets in a melt is comprehensively studied using gold as an example. The kinetics and stages of formation of a gas bubble–attached gold droplet system and the subsequent gold flotation in a melt are investigated. Once a gas bubble and a droplet are in contact, the gold–gas surface and a wetting perimeter are added to the existing slag–gas and gold–slag surfaces. The time is takes for gold droplets about 3 μm in radius to achieve equilibrium is about 10–4 s. Therefore, the formation of an equilibrium bubble–droplet system is fast and does not retard the general process of collection and coarsening of gold droplets by gas bubbles. The flotation condition for the fine (Au, Pt, Pd) droplet–oxide melt system is analyzed. This condition is met for metallic droplets up to 3500 μm in radius.

Cell-Cell Adhesion and Myosin Activity Regulate Cortical Actin Assembly in Mammary Gland Epithelium on Concaved Surface

It has been demonstrated in recent studies that geometry plays an important role in cell behaviors, ranging from mucus production, cell migration and the origination and prorogation of cancer stem cells. Despite the studies on potentially curvature-sensitive proteins at the nanoscale, it is not clear how cells sense curvature and other geometric parameters at cellular and multi-cellular-level. To systematically study whether and how curvature determines cell behaviors, we developed a technique combining 3D printing and soft lithography to fabricate open channel with 60 μm radius. We found that cortical actin is 1.21-fold more enriched in EpH4-EV cells grown on curvature of 60μm−1 when compared to the flat substrate. Inhibition of myosin phosphorylation via blebbistatin and Y-27632 restored the cortical actin formation in cells cultured in channels of high curvature, suggesting myosin is involved in curvature-dependent cortical actin assembly. Furthermore, we demonstrated that cell-cell adhesion is required in the curvature-dependent cortical actin assembly. The prominent cortical actin assembly seen at 60μm−1 was not detected at low cell seeding density resulting in sparse cell-cell contact or after treating cells with β-catenin inhibitor. To summarize, our finding suggests actin cytoskeleton-adherens machinery is responsible for curvature sensing at the multi-cellular level and at the scale of tens of microns.

The effect of high-velocity dust particle impacts on microchannel plate (MCP) detectors

The detection efficiency and durability of a microchannel plate (MCP) detector to direct impacts of high-velocity dust particles is investigated experimentally. A new type of in situ time-of-flight cosmic dust analyzer instrument has been developed, where the ion detector is exposed to occasional impacts of cosmic dust particles. The dust accelerator facility operated at the University of Colorado is used to directly measure the effect of dust impacts on a commercial, off-the-shelf microchannel plate (MCP) detector. The MCP is exposed to approx. 480 dust particle impacts from wide size and velocity ranges of 0.05–1.6 μm radii and 2–35 km/s, respectively. The dust impact events are registered with 96% efficiency. Of these, 57% of the output signals are single charge pulses, and 43% are more complex signals that suggest ion feedback mechanisms within the detector. For all dust detection events, the output charge pulse is significantly larger than those from the detection of single ions or photons. The gain of the MCP detector shows no apparent degradation after the bombardment. In the investigated size/velocity range, the dust particles do not pose a risk of damaging the MCP. Scanning electron microscope images show that the impact generated craters are small, on the order of the size of the impacting particles. The performed measurements and the extrapolation of the results to the worst case expected to occur for the duration of a spaceflight mission indicate that MCP detectors require protection from dust impacts in order to reduce the risk of detector damage for these types of dust analyzer instruments, and a mechanism for providing protection is described.

Fast determination of extra-virgin olive oil acidity by voltammetry and Partial Least Squares regression

In this paper, an approach for the detection of extra-virgin olive oil (EVOO) free-acidity, based on combination of voltammetric profiles (Voltammetry) and Partial Least Squares (PLS) multivariate regression, is described. Voltammetric measurements are performed with a 12.5 μm radius platinum microdisk, directly in the oil samples mixed with 0.5 M of the room temperature ionic liquid (RTIL) tri-hexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide, which acted as a supporting electrolyte, and allows achieving a suitable conductivity in the matrices. Multivariate regression is performed directly on full voltammetric responses recorded over a properly chosen negative potential range and scan rate, where essentially all free fatty acids, characterizing EVOOs, can be reproducibly reduced. PLS regression models are built by employing Italian EVOO samples training sets at different acidity levels (over the range 0.2% w/w - 1.5% w/w; (% w/w) represents mass percentage) and optimized by choosing the optimal complexity, in terms of number of latent variables (LVs). The free-acidity prediction is made through a multivariate model, constructed by using standards of known acidity (determined by the official volumetric titration method) and validated on an external sample set. To show the validity of the proposed method, the PLS/Voltammetry predictions of the free-acidity of a series of commercially available Italian EVOOs, ranging from 0.2 to 0.41 %w/w, are obtained and the values compared with those determined by the official titration approach. Differences found between the two methods are within 5% RSD.

Long Range Multilayer Hybrid Plasmonic Waveguide Components and Integrated Circuit

In this work, CMOS compatible hybrid insulator metal insulator (HIMI) planar plasmonic waveguide based components such as, racetrack ring resonator, y-splitter, coupler and dual parabolic profile nano antenna have been proposed and investigated at 1.55 μm operating wavelength for the first time. The proposed components are analyzed at various parametric variations using CST microwave studio. The proposed racetrack ring resonator offers 153.88 nm free spectral range, 0.3232 nm FWHM and 46.57 dB extinction ratio at 0.40 μm radius and 0.49 μm separation length. Y-splitter divides equal power of 46.85% in both output arms and coupler couples till 86.5% power in coupled arm. The dual parabolic profile nano antenna offers a gain, bandwidth and efficiency of 7.99 dB, 203 THz and 84.56 % respectively. Using all the components, HIMI plasmonic integrated circuits have also been designed and investigated for on chip applications. Proposed components work very efficiently in chip scale integrated circuit. This investigation provides groundwork for future chip scale applications.

Studies of competing evaporation rates of multiple volatile components from a single binary-component aerosol droplet.

The simultaneous evaporation and condensation of multiple volatile components from multicomponent aerosol droplets leads to changes in droplet size, composition and temperature. Measurements and models that capture and predict these dynamic aerosol processes are key to understanding aerosol microphysics in a broad range of contexts. We report measurements of the evaporation kinetics of droplets (initially ∼25 μm radius) formed from mixtures of ethanol and water levitated within a electrodynamic balance over timescales spanning 500 ms to 6 s. Measurements of evaporation into a gas phase of varied relative humidity and temperature are shown to compare well with predictions from a numerical model. We show that water condensation from the gas phase can occur concurrently with ethanol evaporation from aqueous-ethanol droplets. Indeed, water can condense so rapidly during the evaporation of a pure ethanol droplet in a humid environment, driven by the evaporative cooling the droplet experiences, that the droplet becomes pure water within 0.4 s.