Mobile Solid Phase Research Articles

Topologically-imposed vacancies and mobile solid 3He on carbon nanotube

Low dimensional fermionic quantum systems are exceptionally interesting because they reveal distinctive physical phenomena, including among others, topologically protected excitations, edge states, frustration, and fractionalization. Our aim was to confine 3He on a suspended carbon nanotube to form 2-dimensional Fermi-system. Here we report our measurements of the mechanical resonance of the nanotube with adsorbed sub-monolayer down to 10 mK. At intermediate coverages we have observed the famous 1/3 commensurate solid. However, at larger monolayer densities we have observed a quantum phase transition from 1/3 solid to an unknown, soft, and mobile solid phase. We interpret this mobile solid phase as a bosonic commensurate crystal consisting of helium dimers with topologically-induced zero-point vacancies which are delocalized at low temperatures. We thus demonstrate that 3He on a nanotube merges both fermionic and bosonic phenomena, with a quantum phase transition between fermionic solid 1/3 phase and the observed bosonic dimer solid.

Facile Method for Preparation of Silica Coated Monodisperse Superparamagnetic Microspheres

This paper presents a facile method for preparation of silica coated monodisperse superparamagnetic microsphere. Herein, monodisperse porous polystyrene-divinylbenzene microbeads were prepared by seeded emulsion polymerization and subsequently sulfonated with acetic acid/H2SO4. The as-prepared sulfonated macroporous beads were magnetized in presence of Fe2+/Fe3+under alkaline condition and were subjected to silica coating by sol-gel process, providing water compatibility, easily modifiable surface form, and chemical stability. FE-SEM, TEM, FT-IR, and TGA were employed to characterize the silica coated monodisperse magnetic beads (~7.5 μm). The proposed monodisperse magnetic beads can be used as mobile solid phase particles candidate for protein and DNA separation.

Multiphase flow modeling with density functional method

This paper is a review of applications of density functional theory (DFT) in compositional hydrodynamics. The basic idea is representation of the entropy or the Helmholtz energy of the mixture as the functional depending on the molar densities of chemical components (density functional). The hydrodynamics is governed by local conservation laws of chemical components, momentum, and energy, while constitutive relations and boundary conditions are introduced in accordance with the explicit form of the density functional. The general ideas and the history of the DFT in compositional hydrodynamics are discussed. Then the DFT for multiphase multicomponent mixtures is presented including the exposition of the first principles, governing equations and constitutive relations, and explicit expressions of density functional depending on physical situation. The DFT-based numerical simulator is described, and several multiphase simulation results are presented to illustrate the scope and effectiveness of DFT: sessile drop with and without surfactant, droplet breakup in shear flow, and three-phase hydrodynamics with mobile solid phase. Also, two practical scenarios with multiphase simulations in micro-CT porous rock models are presented: two-phase immiscible water-oil flow and three-phase water-gas-condensate flow with phase transitions. All numerical results are obtained by essentially the same code; both the number of chemical components and the Helmholtz energy have been set up in accordance with physical situation.

002.6 A low-cost mobile naat platform forchlamydia trachomatis

We report the development of a low-cost mobile nucleic acid analysis platform (mobiLab) utilising a smartphone-enabled microfluidic device for streamlined analysis of biological samples. Using magnetic particles as a mobile solid phase for nucleic acid capture and transport, fluidic processing is simplified to particle translocation on a robust and scalable cartridge. Process integration facilitated by Bluetooth-enabled microcontrollers enables full control of the instrument by the user with a smartphone application. Each cartridge costs less than $2 using off-the-shelf reagents and materials, an order of magnitude cheaper than $9.98/test for a GeneXpert cartridge. The instrument utilises a microcontroller which controls the rotary bead manipulator, thermal incubation and Bluetooth-based communication with the smartphone application. Each assay consumes approximately 10% of the battery capacity, allowing up to 10 assays to be performed consecutively without access to a power outlet. We designed a single-stream loop-mediated isothermal amplification (LAMP) assay to operate in tandem with the mobiLab platform. We tested the single-stream assay using plasmid targets and were able to capture and amplify 10 3 copies of gene targets. Absence of cross-reactivity with human genomic DNA or other vaginal flora was verified. The platform was validated by testing Chlamydia trachomatis infection from patient-collected vaginal swab samples. Volunteers enrolled in an internet-based Chlamydia screening program, where two sets of swabs were self-collected and mailed back to our lab. One set of swabs was analysed using the gold standard Gen-Probe AC2 CT assay. The second set of swabs was tested using the mobiLab platform. The two results were in agreement for 20 out of 20 samples at a time threshold of 30 min, demonstrating that the droplet assay performance is comparable to the gold standard for the samples tested. To our knowledge, this abstract presents the first smartphone-based NAAT platform that integrates sample preparation, amplification and data processing. Disclosure of interest statement None to disclose.

Magnetic microbead-based enzyme immunoassay for ovalbumin using hydrodynamic voltammetry and fluorometric detection

A paramagnetic microbead-based enzyme immunoassay was demonstrated for detecting ovalbumin (OVA). The immunoassay sandwich was made by attaching a biotinylated antibody to the streptavidin coated beads as a mobile solid phase, capturing antigen, and then exposing the antigen to an antibody conjugated with β-galactosidase. β-Galactosidase converts p-aminophenyl galactopyranoside (PAPG) and fluorescein di-β-D-galactopyranoside (FDG) to p-aminophenol (PAP) and fluorescein, respectively. The current response of PAP generated by the enzymatic reaction of β-galactosidase was detected with hydrodynamic voltammetry in a droplet using a rotating disk electrode (RDE) system. The performance of this electrochemical assay was compared with fluorometric detection of fluorescein produced by the same assay system. The limits of detection for OVA determined by hydrodynamic amperometry and fluorometry were 2.1 nM (43 fmol) and 2.9 nM (58 fmol), respectively. Furthermore, the effects of the conditions commonly found in drinking water supply systems on the OVA assay were also evaluated.

Application of laser ablation ICP-MS and traditional micromorphological techniques to the study of an Alfisol (Sardinia, Italy) in thin sections: Insights into trace element distribution

An innovative methodological approach is proposed in this study, based on the chemical analysis of different portions of soil horizons (illuvial pedofeatures, pedogenic matrix and skeletal parent rock fragments) by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), associated with traditional micromorphological (optical and scanning electron microscopy) techniques. Validation of the LA-ICP-MS technique provides in situ accurate and reproducible (RSD 13–18%) analysis of low concentration trace elements and rare earth elements (REE) in soil samples (0.001–0.1 ppm). Analyses were carried out on thin sections prepared from undisturbed soil samples, collected from three different Bt (argillic, i.e. clay-illuviated) horizons in an Alfisol from the Muravera area (southeastern Sardinia, Italy). The main aims were (i) to develop and test the reliability of a LA-ICP-MS analytical method on soil thin sections and (ii) to explore the idea that concentrations of trace and rare earth elements in the different portions of a soil profile can be used to investigate their distribution, as a response to pedogenetic processes. The three horizons show similar features, particularly in terms of element concentrations and patterns. By comparing the concentration of REE and other trace elements in the clay coatings, the soil matrix and the skeletal rock fragments in the same horizon, a general enrichment trend is observed from the parent rock to the pedogenic matrix up to the illuvial pedofeatures, suggesting a prominent role of pedogenetic processes in element fractionation and distribution during weathering. In particular, the highest concentration of trace elements (and specifically REE) in clay coatings, which represent the most mobile solid phase in the soil profile, indicates that the former can be used as a reliable indicator of soil weathering if a preliminary assessment of the presence of clay coatings is achieved. In addition, the discontinuous trend of some trace elements among soil features of different horizons is consistent with field evidence of slope dynamics, marked by an erosive and depositional discontinuity along the soil profile.

Application of an automated fluidic system using electrochemical bead-based immunoassay to detect the bacteriophage MS2 and ovalbumin

A fully-automated fluidic system for a bead-based immunoassay with electrochemical detection was developed. Assays for the bacteriophage MS2 and ovalbumin (OVA) were demonstrated using this system. Streptavidin-coated paramagnetic microbeads were used as a mobile solid phase. The immunoassay sandwich was made by attaching a biotinylated antibody to the streptavidin-coated beads, capturing antigen, and then exposing the antigen to an antibody conjugated with β-galactosidase. β-Galactosidase converts p-aminophenyl galactopyranoside (PAPG) to p-aminophenol (PAP), which is electrochemically oxidized to p-quinone imine (PQI). The behavior of paramagnetic microbeads in the fluidic system was investigated using beads with immobilized β-galactosidase at different concentrations of beads and flow rates for each procedure in the assay. Furthermore, the fully-automated MS2 and OVA assays were demonstrated using the fluidic system. The limits of detection for MS2 and OVA were 990 (1.6 × 10 11 particles mL −1) and 470 ng mL −1, respectively.

Muddy waters: temporal variation in sediment discharging from a karst spring

Karst aquifers are capable of transporting and discharging large quantities of suspended sediment, which can have an important impact on water quality. Here we present the results of intensive monitoring of sediment discharging from a karst spring in response to two storm events, one following a wet season and the other following a dry season; we describe temporal changes in total suspended solids (TSS), mineralogy, and particle size distribution. Peak concentrations of suspended sediment coincided with changes in aqueous chemistry indicating arrival of surface water, suggesting that much of the discharging sediment had an allochthonous origin. Concentrations of suspended sediment peaked 14–16 h after rainfall, and the bulk of the sediment (approximately 1 metric ton in response to each storm) discharged within 24 h after rainfall. Filtered material included brightly colored fibers and organic matter. Suspended sediments consisted of dolomite, calcite, quartz, and clay. Proportions of each mineral constituent changed as the aquifer response to the storm progressed, indicating varying input from different sediment sources. The hydraulic response of the aquifer to precipitation was well described by changes in parameters obtained from the particle size distribution function, and corresponded to changes seen in TSS and mineralogy. Differences between storms in the quantity and mineralogy of sediment transported suggest that seasonal effects on surface sediment supply may be important. The quantity of sediment discharging and its potential to sorb and transport contaminants indicates that a mobile solid phase should be included in contaminant monitoring and contaminant transport models of karst. Temporal changes in sediment quantity and characteristics and differences between responses to the two storms, however, demonstrate that the process is not easily generalized.

N.M.R. studies of neopentane absorbed upon titanium dioxide

N.M.R. studies of neopentane adsorbed upon titanium dioxide between 80 K and 300 K for coverages between 0·5 and 2 monolayers show three different phases as a function of temperature. Above 200 K the adsorbed neopentane exists as a liquid, and rotational and translational diffusion coefficients have been determined by 13C relaxation times and the magnetic field gradient spin echo method respectively. Above 130 K the neopentane exists in a rotationally mobile solid phase in which rotation about axes both perpendicular and parallel to the surface occurs. On cooling below 130 K there is a gradual transition to a solid in which rotation is permitted only about an axis perpendicular to the surface. In the low temperature solid phase the inter- and intramolecular contributions to the linewidths have been separated using mixtures of neopentane and fully deuterated neopentane. Both these and the rotational diffusion coefficients in the liquid show the neopentane to be oriented with respect to the surface as a tripod.

Quantitative theory for metamorphic differentiation in development of crenulation cleavage

A driving potential for metamorphic differentiation in the development of a crenulation cleavage arises from the difference in the mean stresses acting on the mobile solid phase in the hinge and limb regions of a crenulation. The rate of metamorphic differentiation is proportional to the resulting difference in the mean chemical potential of the solid in fluid-filled pores in the two regions. A comparison of the magnitude of the rate of dilation, representing the addition of the mobile phase (quartz) to the hinge region of a crenulation fold, with the total strain rate indicates when differentiation will be important in natural and experimental settings. Dilation rates comparable to tectonic strain rates of 10 −1 to 10 −14 sec −1 are achieved in pelitic rocks at stress differences of 10 to 40 b.