Wetting and phase separation in soft adhesion

PubMed Central

Jensen, Katharine E.; Sarfati, Raphael; Style, Robert W.; Boltyanskiy, Rostislav; Chakrabarti, Aditi; Chaudhury, Manoj K.; Dufresne, Eric R.

2015-01-01

In the classic theory of solid adhesion, surface energy drives deformation to increase contact area whereas bulk elasticity opposes it. Recently, solid surface stress has been shown also to play an important role in opposing deformation of soft materials. This suggests that the contact line in soft adhesion should mimic that of a liquid droplet, with a contact angle determined by surface tensions. Consistent with this hypothesis, we observe a contact angle of a soft silicone substrate on rigid silica spheres that depends on the surface functionalization but not the sphere size. However, to satisfy this wetting condition without a divergent elastic stress, the gel phase separates from its solvent near the contact line. This creates a four-phase contact zone with two additional contact lines hidden below the surface of the substrate. Whereas the geometries of these contact lines are independent of the size of the sphere, the volume of the phase-separated region is not, but rather depends on the indentation volume. These results indicate that theories of adhesion of soft gels need to account for both the compressibility of the gel network and a nonzero surface stress between the gel and its solvent. PMID:26553989

Sequential, solid-phase assay for biotin in physiologic fluids that correlates with expected biotin status

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mock, D.M.; DuBois, D.B.

1986-03-01

Interest in accurate measurement of biotin concentrations in plasma and urine has been stimulated by recent advances in the understanding of biotin-responsive inborn errors of metabolism and by several reports describing acquired biotin deficiency during parenteral alimentation. This paper presents a biotin assay utilizing radiolabeled avidin in a sequential, solid-phase method; the assay has increased sensitivity compared to previous methods (greater than or equal to 10 fmol/tube), correlates with expected trends in biotin concentrations in blood and urine in a rat model of biotin deficiency, and can utilize commercially available radiolabeled avidin.

Lead-germanium ohmic contact on to gallium arsenide formed by the solid phase epitaxy of germanium: A microstructure study

NASA Astrophysics Data System (ADS)

Radulescu, Fabian

2000-12-01

Driven by the remarkable growth in the telecommunication market, the demand for more complex GaAs circuitry continued to increase in the last decade. As a result, the GaAs industry is faced with new challenges in its efforts to fabricate devices with smaller dimensions that would permit higher integration levels. One of the limiting factors is the ohmic contact metallurgy of the metal semiconductor field effect transistor (MESFET), which, during annealing, induces a high degree of lateral diffusion into the substrate. Because of its limited reaction with the substrate, the Pd-Ge contact seems to be the most promising candidate to be used in the next generation of MESFET's. The Pd-Ge system belongs to a new class of ohmic contacts to compound semiconductors, part of an alloying strategy developed only recently, which relies on solid phase epitaxy (SPE) and solid phase regrowth to "un-pin" the Fermi level at the surface of the compound semiconductor. However, implementing this alloy into an integrated process flow proved to be difficult due to our incomplete understanding of the microstructure evolution during annealing and its implications on the electrical properties of the contact. The microstructure evolution and the corresponding solid state reactions that take place during annealing of the Pd-Ge thin films on to GaAs were studied in connection with their effects on the electrical properties of the ohmic contact. The phase transformations sequence, transition temperatures and activation energies were determined by combining differential scanning calorimetry (DSC) for thermal analysis with transmission electron microscopy (TEM) for microstructure identification. In-situ TEM annealing experiments on the Pd/Ge/Pd/GaAs ohmic contact system have permitted real time determination of the evolution of contact microstructure. The kinetics of the solid state reactions, which occur during ohmic contact formation, were determined by measuring the grain growth rates associated with each phase from the videotape recordings. With the exception of the Pd-GaAs interactions, it was found that four phase transformations occur during annealing of the Pd:Ge thin films on top of GaAs. The microstructural information was correlated with specific ohmic contact resistivity measurements performed in accordance with the transmission line method (TLM) and these results demonstrated that the Ge SPE growth on top of GaAs renders the optimal electrical properties for the contact. By using the focused ion beam (FIB) method to produce microcantilever beams, the residual stress present in the thin film system was studied in connection with the microstructure. Although, the PdGe/epi-Ge/GaAs seemed to be the optimal microstructural configuration, the presence of PdGe at the interface with GaAs did not damage the contact resistivity significantly. These results made it difficult to establish a charge transport mechanism across the interface but they explained the wide processing window associated with this contact.

Immobilization of organic radioactive and non-radioactive liquid waste in a composite matrix

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galkin, Anatoliy; Gelis, Artem V.; Castiglioni, Andrew J.

A method for immobilizing liquid radioactive waste is provided, the method having the steps of mixing waste with polymer to form a non-liquid waste; contacting the non-liquid waste with a solidifying agent to create a mixture, heating the mixture to cause the polymer, waste, and filler to irreversibly bind in a solid phase, and compressing the solid phase into a monolith. The invention also provides a method for immobilizing liquid radioactive waste containing tritium, the method having the steps of mixing liquid waste with polymer to convert the liquid waste to a non-liquid waste, contacting the non-liquid waste with amore » solidifying agent to create a mixture, heating the mixture to form homogeneous, chemically stable solid phase, and compressing the chemically stable solid phase into a final waste form, wherein the polymer comprises approximately a 9:1 weight ratio mixture of styrene block co-polymers and cross linked co-polymers of acrylamides.« less

Visualizing the shape of soft solid and fluid contacts between two surfaces

NASA Astrophysics Data System (ADS)

Pham, Jonathan; Schellenberger, Frank; Kappl, Michael; Vollmer, Doris; Butt, Hans-Jürgen

The soft contact between two surfaces is fundamentally interesting for soft materials and fluid mechanics and relevant for friction and wear. The deformation of soft solid interfaces has received much interest because it interestingly reveals similarities to fluid wetting. We present an experimental route towards visualizing the three-dimensional contact geometry of either liquid-solid (i.e., oil and glass) or solid-solid (i.e., elastomer and glass) interfaces using a home-built combination of confocal microscopy and atomic force microscopy. We monitor the shape of a fluid capillary bridge and the depth of indentation in 3D while simultaneously measuring the force. In agreement with theoretical predictions, the height of the capillary bridge depends on the interfacial tensions. By using a slowly evaporating solvent, we quantify the temporal evolution of the capillary bridge and visualized the influence of pinning points on its shape. The position dependence of the advancing and receding contact angle along the three-phase contact line, particle-liquid-air, is resolved. Extending our system, we explore the contact deformation of soft solids where elasticity, in addition to surface tension, becomes an important factor.

Mixed-phase aerosol particles

NASA Astrophysics Data System (ADS)

Corti, T.; Krieger, U. K.; Koop, T.; Peter, T.

2003-04-01

Within a liquid aerosol particle a solid phase may coexist with the liquid over a wide range of ambient conditions. The optical properties of such particles are of interest for a number of reasons. They will affect the scattering albedo of atmospheric aerosols, may cause depolarisation in lidar measurements, and potentially open a window for studying the internal morphology and physical properties (e.g. wetting properties, diffusion constants) of composite particles in laboratory experiments. In this contribution, we will present results of experimental and theoretical work on mixed-phase aerosol particles. The optical properties of mixed-phase particles depend on the location of the inclusion in the liquid phase, which is determined by the surface tensions of the involved interfaces. In the case of complete wetting, the energetically favoured position of the inclusion is in the volume of the liquid phase. For partial wetting, a position at the surface of the liquid phase is favoured, with the contact angle between the solid, liquid and air being described by Young's equation. For systems with small contact angles, the difference in energy between an inclusion situated at the droplets surface and in its volume may be so small that the thermal energy kT is sufficient to displace the inclusion from the droplet surface into its volume. The critical contact angle depends on the size of the inclusion and the droplet and ranges from 0.1 to 10 degrees. Examples of mixed-phase aerosol particles are aged soot particles and sea salt particles at low relative humidity. For aged soot, contact angles on sulphuric acid clearly above 10 degrees have been reported, so that soot inclusions are expected to be located at the surface of aerosol particles. For mixed-phase sea salt particles, consisting of a solid NaCl inclusion and an aqueous solution of mainly NaCl and MgCl2, our measurements on macroscopic NaCl crystals show a contact angle clearly below 10 degrees and possibly as low as 0.1 degrees. An experimental method - based on measuring photon count statistics - is developed to distinguish in single levitated aerosol particle whether a solid inclusion is located in the volume of the particle or at its surface.

A solid-phase assay for the detection of anti-sperm antibodies.

PubMed

Okada, H; Kamidono, S; Owens, G R; Nagamatsu, G R; Addonizio, J C

1993-05-01

ELISA is an ideal assay method for a large-scale screening of anti-sperm antibodies among a large number of infertile males. However, conventional ELISA with whole spermatozoa needs time-consuming steps of centrifugation. A solid-phase assay used for detecting anti-sperm antibodies was established. This assay is suitable not only for detecting circulating anti-sperm antibodies of IgG, IgM, and IgA subclass simultaneously but also for screening hybridomas secreting anti-sperm monoclonal antibodies (mAbs). The microtiter plates, on which solubilized sperm antigens are fixed, can be stored at -80 degrees C for up to six months without losing reactivity with anti-sperm antibodies. Using this assay, 53 sera (13 were proven positive and 40 were proven negative for sperm agglutination antibody) were tested. Although the false-negative rate was 0%, the false-positive rate was 32%. One thousand one hundred sixty-five supernatants from hybridomas constructed with splenocytes of mice who were hyperimmunized with human sperm and nonsecreting myeloma cells were tested by this solid-phase assay and two anti-sperm mAb secreting clones were selected and established. It is recommended that for research work this assay could be used for the first screening of the hybridoma secreting anti-sperm mAb, and for clinical use this assay might be suitable for the first screening of sera of infertile patients. However, conventional bioassays should follow to confirm the biological meaning of the positivity.

Robotic solid phase extraction and high performance liquid chromatographic analysis of ranitidine in serum or plasma.

PubMed

Lloyd, T L; Perschy, T B; Gooding, A E; Tomlinson, J J

1992-01-01

A fully automated assay for the analysis of ranitidine in serum and plasma, with and without an internal standard, was validated. It utilizes robotic solid phase extraction with on-line high performance liquid chromatographic (HPLC) analysis. The ruggedness of the assay was demonstrated over a three-year period. A Zymark Py Technology II robotic system was used for serial processing from initial aspiration of samples from original collection containers, to final direct injection onto the on-line HPLC system. Automated serial processing with on-line analysis provided uniform sample history and increased productivity by freeing the chemist to analyse data and perform other tasks. The solid phase extraction efficiency was 94% throughout the assay range of 10-250 ng/mL. The coefficients of variation for within- and between-day quality control samples ranged from 1 to 6% and 1 to 5%, respectively. Mean accuracy for between-day standards and quality control results ranged from 97 to 102% of the respective theoretical concentrations.

ViriChip: a solid phase assay for detection and identification of viruses by atomic force microscopy

NASA Astrophysics Data System (ADS)

Nettikadan, Saju R.; Johnson, James C.; Vengasandra, Srikanth G.; Muys, James; Henderson, Eric

2004-03-01

Bionanotechnology can be viewed as the integration of tools and concepts in nanotechnology with the attributes of biomolecules. We report here on an atomic force microscopy-immunosensor assay (AFMIA) that couples AFM with solid phase affinity capture of biological entities for the rapid detection and identification of group B coxsackievirus particles. Virus identification is based on type-specific immunocapture and the morphological properties of the captured viruses as obtained by the AFM. Representatives of the six group B coxsackieviruses have been specifically captured from 1 µl volumes of clarified cell lysates, body fluids and environmental samples. Concentration and kinetic profiles for capture indicate that detection is possible at 103 TCID50 µl-1 and the dynamic range of the assay spans three logs. The results demonstrate that the melding of a nanotechnological tool (AFM) with biotechnology (solid phase immunocapture of virus particles) can create a clinically relevant platform, useful for the detection and identification of enterovirus particles in a variety of samples.

Detection of HLA Antibodies in Organ Transplant Recipients – Triumphs and Challenges of the Solid Phase Bead Assay

PubMed Central

Tait, Brian D.

2016-01-01

This review outlines the development of human leukocyte antigen (HLA) antibody detection assays and their use in organ transplantation in both antibody screening and crossmatching. The development of sensitive solid phase assays such as the enzyme-linked immunosorbent assay technique, and in particular the bead-based technology has revolutionized this field over the last 10–15 years. This revolution however has created a new paradigm in clinical decision making with respect to the detection of low level pretransplant HLA sensitization and its clinical relevance. The relative sensitivities of the assays used are discussed and the relevance of conflicting inter-assay results. Each assay has its advantages and disadvantages and these are discussed. Over the last decade, the bead-based assay utilizing the Luminex® fluorocytometer instrument has become established as the “gold standard” for HLA antibody testing. However, there are still unresolved issues surrounding this technique, such as the presence of denatured HLA molecules on the beads which reveal cryptic epitopes and the issue of appropriate fluorescence cut off values for positivity. The assay has been modified to detect complement binding (CB) in addition to non-complement binding (NCB) HLA antibodies although the clinical relevance of the CB and NCB IgG isotypes is not fully resolved. The increase sensitivity of the Luminex® bead assay over the complement-dependent cytotoxicity crossmatch has permitted the concept of the “virtual crossmatch” whereby the crossmatch is predicted to a high degree of accuracy based on the HLA antibody specificities detected by the solid phase assay. Dialog between clinicians and laboratory staff on an individual patient basis is essential for correct clinical decision making based on HLA antibody results obtained by the various techniques. PMID:28018342

A thermodynamic model of contact angle hysteresis.

PubMed

Makkonen, Lasse

2017-08-14

When a three-phase contact line moves along a solid surface, the contact angle no longer corresponds to the static equilibrium angle but is larger when the liquid is advancing and smaller when the liquid is receding. The difference between the advancing and receding contact angles, i.e., the contact angle hysteresis, is of paramount importance in wetting and capillarity. For example, it determines the magnitude of the external force that is required to make a drop slide on a solid surface. Until now, fundamental origin of the contact angle hysteresis has been controversial. Here, this origin is revealed and a quantitative theory is derived. The theory is corroborated by the available experimental data for a large number of solid-liquid combinations. The theory is applied in modelling the contact angle hysteresis on a textured surface, and these results are also in quantitative agreement with the experimental data.

Paper-based solid-phase nucleic acid hybridization assay using immobilized quantum dots as donors in fluorescence resonance energy transfer.

PubMed

Noor, M Omair; Shahmuradyan, Anna; Krull, Ulrich J

2013-02-05

A paper-based solid-phase assay is presented for transduction of nucleic acid hybridization using immobilized quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET). The surface of paper was modified with imidazole groups to immobilize QD-probe oligonucleotide conjugates that were assembled in solution. Green-emitting QDs (gQDs) were FRET-paired with Cy3 acceptor. Hybridization of Cy3-labeled oligonucleotide targets provided the proximity required for FRET-sensitized emission from Cy3, which served as an analytical signal. The assay exhibited rapid transduction of nucleic acid hybridization within minutes. Without any amplification steps, the limit of detection of the assay was found to be 300 fmol with the upper limit of the dynamic range at 5 pmol. The implementation of glutathione-coated QDs for the development of nucleic acid hybridization assay integrated on a paper-based platform exhibited excellent resistance to nonspecific adsorption of oligonucleotides and showed no reduction in the performance of the assay in the presence of large quantities of noncomplementary DNA. The selectivity of nucleic acid hybridization was demonstrated by single-nucleotide polymorphism (SNP) detection at a contrast ratio of 19 to 1. The reuse of paper over multiple cycles of hybridization and dehybridization was possible, with less than 20% reduction in the performance of the assay in five cycles. This work provides an important framework for the development of paper-based solid-phase QD-FRET nucleic acid hybridization assays that make use of a ratiometric approach for detection and analysis.

Surface Stresses and a Force Balance at a Contact Line.

PubMed

Liang, Heyi; Cao, Zhen; Wang, Zilu; Dobrynin, Andrey V

2018-06-26

Results of the coarse-grained molecular dynamics simulations are used to show that the force balance analysis at the triple-phase contact line formed at an elastic substrate has to include a quartet of forces: three surface tensions (surface free energies) and an elastic force per unit length. In the case of the contact line formed by a droplet on an elastic substrate an elastic force is due to substrate deformation generated by formation of the wetting ridge. The magnitude of this force f el is proportional to the product of the ridge height h and substrate shear modulus G. Similar elastic line force should be included in the force analysis at the triple-phase contact line of a solid particle in contact with an elastic substrate. For this contact problem elastic force obtained from contact angles and surface tensions is a sum of the elastic forces acting from the side of a solid particle and an elastic substrate. By considering only three line forces acting at the triple-phase contact line, one implicitly accounts the bulk stress contribution as a part of the resultant surface stresses. This "contamination" of the surface properties by a bulk contribution could lead to unphysically large values of the surface stresses in soft materials.

Antibody class capture assays for varicella-zoster virus.

PubMed Central

Forghani, B; Myoraku, C K; Dupuis, K W; Schmidt, N J

1984-01-01

Pooled monoclonal antibodies to varicella-zoster virus (VZV) were used as "detector" antibodies in a four-phase enzyme immunofluorescence assay for determination of immunoglobulin M (IgM), IgA, and IgG antibodies to VZV. Polyclonal antisera specific for heavy chains of human IgM, IgA, and IgG were employed as "capture" antibodies on the solid phase. The antibody class capture assay (ACCA) for VZV IgM antibody detected high titers of virus-specific IgM in all patients with varicella and in 5 of 10 zoster patients. VZV IgM antibody was not detected in patients with primary herpes simplex virus infections or in other individuals without active VZV infection, with one exception, a patient with encephalitis who had other serological findings compatible with a reactivated VZV infection. VZV-specific IgA and IgG antibody titers demonstrable by ACCA were compared with those measured by solid-phase indirect enzyme immunofluorescence assay (EIFA). VZV IgA antibody titers detected in patients with varicella and zoster were variable and could not be considered to be reliable markers of active VZV infection. IgA antibody titers detected by ACCA tended to be higher than those demonstrated by solid-phase indirect EIFA in varicella and zoster patients. VZV IgG antibody titers detected by ACCA in patients with varicella, and to a lesser extent in zoster patients, were as high as or higher than those demonstrated by solid-phase indirect EIFA. However, ACCA was totally insensitive in detecting VZV IgG antibody in individuals with past infections with VZV and would not be a suitable approach for determination of immunity status to VZV. PMID:6330163

Study on the mechanism of liquid phase sintering (M-12)

NASA Technical Reports Server (NTRS)

Kohara, S.

1993-01-01

The objectives were to (1) obtain the data representing the growth rate of solid particles in a liquid matrix without the effect of gravity; and (2) reveal the growth behavior of solid particles during liquid phase sintering using the data obtained. Nickel and tungsten are used as the constituent materials in liquid phase sintering. The properties of the constituent metals are given. When a compact of the mixture of tungsten and nickel powders is heated and kept at 1550 C, nickel melts down but tungsten stays solid. As the density of tungsten is much greater than that of nickel, the sedimentation of tungsten particles occurs in the experiment on Earth. The difference between the experiments on Earth and in space is illustrated. The tungsten particles sink to the bottom and are brought into contact with each other. The resulting pressure at the contact point causes the accelerated dissolution of tungsten. Consequently, flat surfaces are formed at the contact sites. As a result of dissolution and reprecipitation of tungsten, the shape of particles changes to a polygon. This phenomenon is called 'flattening.' An example of flattening of tungsten particles is shown. Thus, the data obtained by the experiment on Earth may not represent the exact growth behavior of the solid particles in a liquid matrix. If the experiments were done in a microgravity environment, the data corresponding to the theoretical growth behavior of solid particles could be achieved.

Quantification of diphtheria toxin mediated ADP-ribosylation in a solid-phase assay.

PubMed

Bachran, Christopher; Sutherland, Mark; Bachran, Diana; Fuchs, Hendrik

2007-09-01

Because of reduced vaccination programs, the number of diphtheria infections has increased in the last decade. Diphtheria toxin (DT) is expressed by Corynebacterium diphtheriae and is responsible for the lethality of diphtheria. DT inhibits cellular protein synthesis by ADP-ribosylation of the eukaryotic elongation factor 2 (eEF2). No in vitro system for the quantification of DT enzymatic activity exists. We developed a solid-phase assay for the specific detection of ADP-ribosylation by DT. Solid phase-bound his-tag eEF2 is ADP-ribosylated by toxins using biotinylated NAD(+) as substrate, and the transferred biotinylated ADP-ribose is detected by streptavidin-peroxidase. DT enzymatic activity correlated with absorbance. We measured the amount of ADP-ribosylated eEF2 after precipitation with streptavidin-Sepharose. Quantification was done after Western blotting and detection with anti-his-tag antibody using an LAS-1000 System. The assay detected enzymatically active DT at 30 ng/L, equivalent to 5 mU/L ADP-ribosylating activity. Pseudomonas exotoxin A (PE) activity was also detected at 100 ng/L. We verified the assay with chimeric toxins composed of the catalytic domain of DT or PE and a tumor-specific ligand. These chimeric toxins revealed increased signals at 1000 ng/L. Heat-inactivated DT and cholera toxin that ADP-ribosylates G-proteins did not show any signal increase. The assay may be the basis for the development of a routine diagnostic assay for the detection of DT activity and highly specific inhibitors of DT.

Insecticidal evaluation of essential oils of Citrus sinensis L. (Myrtales: Myrtaceae) against housefly, Musca domestica L. (Diptera: Muscidae).

PubMed

Kumar, Peeyush; Mishra, Sapna; Malik, Anushree; Satya, Santosh

2012-05-01

The housefly, Musca domestica L., is one of the most common insects, associated with vectoring of various etiological agents. In order to search for effective control agent, the essential oil of sweet orange [Citrus sinensis (L.) Osbeck] was evaluated for its insecticidal activity against the larvae and pupae of housefly using contact toxicity and fumigation bioassays. In the contact toxicity assay, lethal concentration, LC(50) of C. sinensis essential oil against housefly larvae, varied between 3.93 and 0.71 μl/cm(2) for different observation days, while lethal time, LT(50), varied between 5.8 to 2.3 days. Mortality of larvae were significant with different concentrations (F = 2.79, df = 4, P < 0.05) and time (F = 6.69, df = 3, P < 0.01). In fumigant assay for housefly larvae, LC(50) of 71.2 and 52.6 μl/l was obtained in 24 and 48 h, respectively. Scanning electron microscopy of oil treated larvae revealed extreme dehydration and surface distortion while control larvae were free from any of the above symptoms and presented smooth surface, conforming effect of essential oil on housefly larvae. Percentage inhibition rate of oil against housefly pupae was 27.3-72.7% for contact toxicity and 46.4-100% for fumigation assay. Compositional analysis of C. sinensis essential oil using gas chromatography/mass spectrometry (GC-MS) revealed D: -limonene (73.24%), α-pinene (5.86%) and myrcene (4.45%) as major components whereas its vapour profile (solid-phase micro extraction-GC/MS) was dominated by D: -limonene at 92.57%. Significant activity of C. sinensis essential oil against larvae and pupae of housefly, pave the way for its use as eco-friendly housefly control measure.

Experiments in ultrasonic flaw detection using a MEMS transducer

NASA Astrophysics Data System (ADS)

Jain, Akash; Greve, David W.; Oppenheim, Irving J.

2003-08-01

In earlier work we developed a MEMS phased array transducer, fabricated in the MUMPs process, and we reported on initial experimental studies in which the device was affixed into contact with solids. We demonstrated the successful detection of signals from a conventional ultrasonic source, and the successful localization of the source in an off-axis geometry using phased array signal processing. We now describe the predicted transmission and coupling characteristics for such devices in contact with solids, demonstrating reasonable agreement with experimental behavior. We then describe the results of flaw detection experiments, as well as results for fluid-coupled detectors.

Utilizing thin-film solid-phase extraction to assess the effect of organic carbon amendments on the bioavailability of DDT and dieldrin to earthworms

USDA-ARS?s Scientific Manuscript database

Improved approaches are needed to rapidly and accurately assess the bioavailability of persistent, hydrophobic organic compounds in soils at contaminated sites. The performance of a thin-film solid-phase extraction (TF-SPE) assay using vials coated with ethylene vinyl acetate polymer was compared to...

Interfacial chemistry and the design of solid-phase nucleic acid hybridization assays using immobilized quantum dots as donors in fluorescence resonance energy transfer.

PubMed

Algar, W Russ; Krull, Ulrich J

2011-01-01

The use of quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET) offer several advantages for the development of multiplexed solid-phase QD-FRET nucleic acid hybridization assays. Designs for multiplexing have been demonstrated, but important challenges remain in the optimization of these systems. In this work, we identify several strategies based on the design of interfacial chemistry for improving sensitivity, obtaining lower limits of detection (LOD) and enabling the regeneration and reuse of solid-phase QD-FRET hybridization assays. FRET-sensitized emission from acceptor dyes associated with hybridization events at immobilized QD donors provides the analytical signal in these assays. The minimization of active sensing area reduces background from QD donor PL and allows the resolution of smaller amounts of acceptor emission, thus lowering the LOD. The association of multiple acceptor dyes with each hybridization event can enhance FRET efficiency, thereby improving sensitivity. Many previous studies have used interfacial protein layers to generate selectivity; however, transient destabilization of these layers is shown to prevent efficient regeneration. To this end, we report a protein-free interfacial chemistry and demonstrate the specific detection of as little as 2 pmol of target, as well as an improved capacity for regeneration.

Interfacial Chemistry and the Design of Solid-Phase Nucleic Acid Hybridization Assays Using Immobilized Quantum Dots as Donors in Fluorescence Resonance Energy Transfer

PubMed Central

Algar, W. Russ; Krull, Ulrich J.

2011-01-01

The use of quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET) offer several advantages for the development of multiplexed solid-phase QD-FRET nucleic acid hybridization assays. Designs for multiplexing have been demonstrated, but important challenges remain in the optimization of these systems. In this work, we identify several strategies based on the design of interfacial chemistry for improving sensitivity, obtaining lower limits of detection (LOD) and enabling the regeneration and reuse of solid-phase QD-FRET hybridization assays. FRET-sensitized emission from acceptor dyes associated with hybridization events at immobilized QD donors provides the analytical signal in these assays. The minimization of active sensing area reduces background from QD donor PL and allows the resolution of smaller amounts of acceptor emission, thus lowering the LOD. The association of multiple acceptor dyes with each hybridization event can enhance FRET efficiency, thereby improving sensitivity. Many previous studies have used interfacial protein layers to generate selectivity; however, transient destabilization of these layers is shown to prevent efficient regeneration. To this end, we report a protein-free interfacial chemistry and demonstrate the specific detection of as little as 2 pmol of target, as well as an improved capacity for regeneration. PMID:22163951

Interaction of immobilized avidin with an aequorin-biotin conjugate: an aequorin-linked assay for biotin.

PubMed

Feltus, A; Ramanathan, S; Daunert, S

1997-12-01

Biotinylated recombinant aequorin was used in the development of a heterogeneous bioluminescence binding assay for biotin. This assay is based on a competition between a biotinylated aequorin conjugate and biotin for the binding sites of avidin immobilized on solid particles. Dose-response curves were obtained that relate solid-phase aequorin activity to the concentration of biotin. Under certain experimental conditions these curves were biphasic; i.e., as the biotin concentration increased, the solid-phase aequorin activity first increased reaching a maximum and then decreased at higher biotin concentrations. This "hook" effect was observed with four different types of immobilization supports. The effect was more pronounced when low concentrations of aequorin-biotin conjugate were used, and diminished at a high conjugate concentration. This behavior indicates a possible positive cooperativity in the interaction between the immobilized avidin and biotin. Scatchard plot analysis was also consistent with a positive cooperativity mechanism. By using the ascending portion of the dose-response curve, the detection limit of the assay for biotin was 1 x 10(-15) M (100 zmol of biotin in the sample). Copyright 1997 Academic Press.

Quantitative determination of risperidone, paliperidone and olanzapine in human serum by liquid chromatography-tandem mass spectrometry coupled with on-line solid-phase extraction.

PubMed

Ruan, Can-Jun; Guo, Wei; Zhou, Miao; Guo, Gui-Xin; Wang, Chuan-Yue; Li, Wen-Biao; de Leon, Jose

2018-07-01

A recent guideline recommends therapeutic drug monitoring for risperidone, paliperidone and olanzapine, which are frequently used second-generation antipsychotics. We developed a simple high-performance liquid chromatography-tandem mass spectrometry coupled with an online solid-phase extraction method that can be used to measure risperidone, paliperidone and olanzapine using small (40 μL) samples. The analytes were extracted from serum samples automatically pre-concentrated and purified by C 8 (5 μm, 2.1 × 30 mm) solid-phase extraction cartridges, then chromatographed on an Xbidge™ C 18 column (3.5 μm, 100 × 2.1 mm) thermostatted at 30°C with a mobile phase consisting of 70% acetonitrile and 30% ammonium hydroxide 1% solution at an isocratic flow rate of 0.3 mL/min, and detected with tandem mass spectrometry. The assay was validated in the concentration range from 2.5 to 160 ng/mL. Intra- and inter-day precision for all analytes was between 1.1 and 8.2%; method accuracy was between 6.6 and 7.6%. The risperidone and paliperidone assay was compared with a high-performance liquid chromatography-ultraviolet assay currently used in our hospital for risperidone and paliperidone therapeutic drug monitoring, and the results of weighted Deming regression analysis showed good agreement. For the olanzapine assay, we compared 20 samples in separate re-assays on different days; all the relative errors were within the 20% recommended limit. Copyright © 2018 John Wiley & Sons, Ltd.

Contact angle of sessile drops in Lennard-Jones systems.

PubMed

Becker, Stefan; Urbassek, Herbert M; Horsch, Martin; Hasse, Hans

2014-11-18

Molecular dynamics simulations are used for studying the contact angle of nanoscale sessile drops on a planar solid wall in a system interacting via the truncated and shifted Lennard-Jones potential. The entire range between total wetting and dewetting is investigated by varying the solid-fluid dispersive interaction energy. The temperature is varied between the triple point and the critical temperature. A correlation is obtained for the contact angle in dependence of the temperature and the dispersive interaction energy. Size effects are studied by varying the number of fluid particles at otherwise constant conditions, using up to 150,000 particles. For particle numbers below 10,000, a decrease of the contact angle is found. This is attributed to a dependence of the solid-liquid surface tension on the droplet size. A convergence to a constant contact angle is observed for larger system sizes. The influence of the wall model is studied by varying the density of the wall. The effective solid-fluid dispersive interaction energy at a contact angle of θ = 90° is found to be independent of temperature and to decrease linearly with the solid density. A correlation is developed that describes the contact angle as a function of the dispersive interaction, the temperature, and the solid density. The density profile of the sessile drop and the surrounding vapor phase is described by a correlation combining a sigmoidal function and an oscillation term.

ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT, PCB DETECTION TECHNOLOGY, HYBRIZYME DELFIA TM ASSAY

EPA Science Inventory

The DELFIA PCB Assay is a solid-phase time-resolved fluoroimmunoassay based on the sequential addition of sample extract and europium-labeled PCB tracer to a monoclonal antibody reagent specific for PCBs. In this assay, the antibody reagent and sample extract are added to a strip...

Analysis by rotavirus gene 6 reverse transcriptase-polymerase chain reaction assay of rotavirus-positive gastroenteritis cases observed during the vaccination phase of the Rotavirus Efficacy and Safety Trial (REST)

PubMed Central

Matson, David O; Vesikari, Timo; Dennehy, Penelope; Dallas, Michael D; Goveia, Michelle G; Itzler, Robbin F; Ciarlet, Max

2014-01-01

During the vaccination phase of the Rotavirus Efficacy and Safety Trial (REST), the period between the administration of dose 1 through 13 days after the administration of dose 3, there were more wild-type rotavirus gastroenteritis (RVGE) cases among vaccine recipients compared with placebo recipients using the protocol-specified microbiological plaque assay in the clinical-efficacy cohort, a subset of subjects where vaccine efficacy against RVGE of any severity was assessed. In this study, a rotavirus genome segment 6-based reverse transcriptase–polymerase chain reaction assay was applied post hoc to clarify the accuracy of type categorization of all these RVGE cases in vaccine recipients during the vaccination phase of REST. The assay characterized 147 (90%) of 163 re-assayed RVGE cases or rotavirus-associated health care contacts as type-determinable: either wild-type or vaccine-type rotavirus strains. In the clinical-efficacy cohort (N = 5673), 19 (18.8%) of 101 samples from RVGE cases contained wild-type rotavirus, 70 (69.3%) vaccine virus, and 12 (11.9%) were indeterminable. In the large-scale cohort (N = 68,038), 10 (34.5%) of 29 samples from RVGE-related health care contacts contained wild-type rotavirus strains, 15 (51.7%) vaccine-type rotavirus strains, and 4 (13.8%) were indeterminable. Of the 33 samples from RVGE cases in placebo recipients, all were confirmed to contain wild-type rotaviruses. Altogether, this post-hoc re-evaluation showed that the majority (75%) of type-determinable RVGE cases or health care contacts that occurred during the vaccination phase of REST in vaccine recipients were associated with vaccine-type rotavirus strains rather than wild-type rotavirus strains. PMID:25424931

Analysis by rotavirus gene 6 reverse transcriptase-polymerase chain reaction assay of rotavirus-positive gastroenteritis cases observed during the vaccination phase of the Rotavirus Efficacy and Safety Trial (REST).

PubMed

Matson, David O; Vesikari, Timo; Dennehy, Penelope; Dallas, Michael D; Goveia, Michelle G; Itzler, Robbin F; Ciarlet, Max

2014-01-01

During the vaccination phase of the Rotavirus Efficacy and Safety Trial (REST), the period between the administration of dose 1 through 13 days after the administration of dose 3, there were more wild-type rotavirus gastroenteritis (RVGE) cases among vaccine recipients compared with placebo recipients using the protocol-specified microbiological plaque assay in the clinical-efficacy cohort, a subset of subjects where vaccine efficacy against RVGE of any severity was assessed. In this study, a rotavirus genome segment 6-based reverse transcriptase-polymerase chain reaction assay was applied post hoc to clarify the accuracy of type categorization of all these RVGE cases in vaccine recipients during the vaccination phase of REST. The assay characterized 147 (90%) of 163 re-assayed RVGE cases or rotavirus-associated health care contacts as type-determinable: either wild-type or vaccine-type rotavirus strains. In the clinical-efficacy cohort (N = 5673), 19 (18.8%) of 101 samples from RVGE cases contained wild-type rotavirus, 70 (69.3%) vaccine virus, and 12 (11.9%) were indeterminable. In the large-scale cohort (N = 68,038), 10 (34.5%) of 29 samples from RVGE-related health care contacts contained wild-type rotavirus strains, 15 (51.7%) vaccine-type rotavirus strains, and 4 (13.8%) were indeterminable. Of the 33 samples from RVGE cases in placebo recipients, all were confirmed to contain wild-type rotaviruses. Altogether, this post-hoc re-evaluation showed that the majority (75%) of type-determinable RVGE cases or health care contacts that occurred during the vaccination phase of REST in vaccine recipients were associated with vaccine-type rotavirus strains rather than wild-type rotavirus strains.

Identification of volatile organic compounds emitted by a naturally aged book using solid-phase microextraction/gas chromatography/mass spectrometry.

PubMed

Lattuati-Derieux, Agnès; Bonnassies-Termes, Sylvette; Lavédrine, Bertrand

2004-02-13

Solid-phase microextraction (SPME) coupled to gas chromatography/mass spectrometry (GC/MS) has been applied to the analysis of volatile organic compounds emitted from a naturally aged groundwood pulp paper originating from an old book in order to access the products produced through the decomposition reactions occurring in paper upon ageing. Two different extraction methods were developed and compared: headspace SPME and contact SPME. The influence of few extraction parameters were tested in order to define the best extraction conditions. An optimised non-destructive contact SPME method was elaborated and allowed the characterisation of more than 50 individual constituents.

Direct determination of three-phase contact line properties on nearly molecular scale

DOE PAGES

Winkler, P. M.; McGraw, R. L.; Bauer, P. S.; ...

2016-05-17

Wetting phenomena in multi-phase systems govern the shape of the contact line which separates the different phases. For liquids in contact with solid surfaces wetting is typically described in terms of contact angle. While in macroscopic systems the contact angle can be determined experimentally, on the molecular scale contact angles are hardly accessible. Here we report the first direct experimental determination of contact angles as well as contact line curvature on a scale of the order of 1nm. For water nucleating heterogeneously on Ag nanoparticles we find contact angles around 15 degrees compared to 90 degrees for the corresponding macroscopicallymore » measured equilibrium angle. The obtained microscopic contact angles can be attributed to negative line tension in the order of –10 –10 J/m that becomes increasingly dominant with increasing curvature of the contact line. Furthermore, these results enable a consistent theoretical description of heterogeneous nucleation and provide firm insight to the wetting of nanosized objects.« less

Fluidics platform and method for sample preparation

DOEpatents

Benner, Henry W.; Dzenitis, John M.

2016-06-21

Provided herein are fluidics platforms and related methods for performing integrated sample collection and solid-phase extraction of a target component of the sample all in one tube. The fluidics platform comprises a pump, particles for solid-phase extraction and a particle-holding means. The method comprises contacting the sample with one or more reagents in a pump, coupling a particle-holding means to the pump and expelling the waste out of the pump while the particle-holding means retains the particles inside the pump. The fluidics platform and methods herein described allow solid-phase extraction without pipetting and centrifugation.

Rapid and sensitive Nitrosomonas europaea biosensor assay for quantification of bioavailable ammonium sensu strictu in soil.

PubMed

Nguyen, Minh Dong; Risgaard-Petersen, Nils; Sørensen, Jan; Brandt, Kristian K

2011-02-01

Knowledge on bioavailable ammonium sensu strictu (i.e., immediately available for cellular uptake) in soil is required to understand nutrient uptake processes in microorganisms and thus of vital importance for plant production. We here present a novel ammonium biosensor approach based on the lithoautotrophic ammonia-oxidizing bacterium Nitrosomonas europaea transformed with a luxAB sensor plasmid. Bioluminescence-based ammonium detection was achieved within 10 min with a quantification limit in liquid samples of ∼20 μM and a linear response range up to 400 μM. Biosensor and conventional chemical quantification of ammonium in soil solutions agreed well across a range of sample and assay conditions. The biosensor was subsequently applied for a solid phase-contact assay allowing for direct interaction of biosensor cells with soil particle-associated (i.e., exchangeable plus fixed) ammonium. The assay successfully quantified bioavailable ammonium even in unfertilized soil and demonstrated markedly higher ratios of bioavailable ammonium to water- or 2 M KCl-exchangeable ammonium in anoxic soil than in corresponding oxic soil. Particle-associated ammonium contributed by at least 74% and 93% of the total bioavailable pool in oxic and anoxic soil, respectively. The N. europaea biosensor should have broad relevance for environmental monitoring of bioavailable ammonium and processes depending on ammonium bioavailability.

Housefly (Musca domestica L.) control potential of Cymbopogon citratus Stapf. (Poales: Poaceae) essential oil and monoterpenes (citral and 1,8-cineole).

PubMed

Kumar, Peeyush; Mishra, Sapna; Malik, Anushree; Satya, Santosh

2013-01-01

In spite of being a major vector for several domestic, medical, and veterinary pests, the control aspect of the common housefly, Musca domestica L. (Diptera: Muscidae) is often neglected. In the present study, the essential oil of Cymbopogon citratus and its major components were evaluated for control of housefly. The chemical composition analysis of C. citratus oil by gas chromatographic mass spectrometry (GC-MS) revealed citral (47 %) and 1,8-cineole (7.5 %) as principal components. The analysis of oil vapor by solid phase microextraction (SPME/GC-MS) showed increase in citral (74.9 %) and 1,8-cineole (8.6 %) content. Assay of oil against housefly larvae and pupae through contact toxicity assay showed lethal concentration (LC)(50) value of 0.41 μl/cm(2) and of percentage inhibition rate (PIR) of 77.3 %, respectively. Fumigation assay was comparatively more effective with LC(50) of 48.6 μl/L against housefly larvae, and a PIR value of 100 % against housefly pupae. The monoterpenes, citral, and 1,8-cineole, when assessed for their insecticidal activity against housefly larvae, showed LC(50) of 0.002 and 0.01 μl/cm(2) (contact toxicity assay) and LC(50) of 3.3 and 2.4 μl/L (fumigation assay). For pupicidal assay, both citral and 1,8-cineole had a PIR value of 100 %. High efficacy of citral and 1,8-cineole against housefly, established them to be an active insecticidal agent of C. citratus oil. The study demonstrates potentiality of C. citratus oil as an excellent insecticide for housefly control, and the results open up the opportunity of oil/monoterpenes being developed into an eco-friendly, economical, and acceptable product.

Dispersed bubble reactor for enhanced gas-liquid-solids contact and mass transfer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vimalchand, Pannalal; Liu, Guohai; Peng, WanWang

An apparatus to promote gas-liquid contact and facilitate enhanced mass transfer. The dispersed bubble reactor (DBR) operates in the dispersed bubble flow regime to selectively absorb gas phase constituents into the liquid phase. The dispersion is achieved by shearing the large inlet gas bubbles into fine bubbles with circulating liquid and additional pumped liquid solvent when necessary. The DBR is capable of handling precipitates that may form during absorption or fine catalysts that may be necessary to promote liquid phase reactions. The DBR can be configured with multistage counter current flow sections by inserting concentric cylindrical sections into the risermore » to facilitate annular flow. While the DBR can absorb CO.sub.2 in liquid solvents that may lead to precipitates at high loadings, it is equally capable of handling many different types of chemical processes involving solids (precipitates/catalysts) along with gas and liquid phases.« less

Solid-phase extraction microfluidic devices for matrix removal in trace element assay of actinide materials

DOE PAGES

Gao, Jun; Manard, Benjamin Thomas; Castro, Alonso; ...

2017-02-02

Advances in sample nebulization and injection technology have significantly reduced the volume of solution required for trace impurity analysis in plutonium and uranium materials. Correspondingly, we have designed and tested a novel chip-based microfluidic platform, containing a 100-µL or 20-µL solid-phase microextraction column, packed by centrifugation, which supports nuclear material mass and solution volume reductions of 90% or more compared to standard methods. Quantitative recovery of 28 trace elements in uranium was demonstrated using a UTEVA chromatographic resin column, and trace element recovery from thorium (a surrogate for plutonium) was similarly demonstrated using anion exchange resin AG MP-1. Of ninemore » materials tested, compatibility of polyvinyl chloride (PVC), polypropylene (PP), and polytetrafluoroethylene (PTFE) chips with the strong nitric acid media was highest. Finally, the microcolumns can be incorporated into a variety of devices and systems, and can be loaded with other solid-phase resins for trace element assay in high-purity metals.« less

Solid-phase extraction microfluidic devices for matrix removal in trace element assay of actinide materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Jun; Manard, Benjamin Thomas; Castro, Alonso

Advances in sample nebulization and injection technology have significantly reduced the volume of solution required for trace impurity analysis in plutonium and uranium materials. Correspondingly, we have designed and tested a novel chip-based microfluidic platform, containing a 100-µL or 20-µL solid-phase microextraction column, packed by centrifugation, which supports nuclear material mass and solution volume reductions of 90% or more compared to standard methods. Quantitative recovery of 28 trace elements in uranium was demonstrated using a UTEVA chromatographic resin column, and trace element recovery from thorium (a surrogate for plutonium) was similarly demonstrated using anion exchange resin AG MP-1. Of ninemore » materials tested, compatibility of polyvinyl chloride (PVC), polypropylene (PP), and polytetrafluoroethylene (PTFE) chips with the strong nitric acid media was highest. Finally, the microcolumns can be incorporated into a variety of devices and systems, and can be loaded with other solid-phase resins for trace element assay in high-purity metals.« less

How can we reduce costs of solid-phase multiplex-bead assays used to determine anti-HLA antibodies?

PubMed

Kamburova, E G; Wisse, B W; Joosten, I; Allebes, W A; van der Meer, A; Hilbrands, L B; Baas, M C; Spierings, E; Hack, C E; van Reekum, F E; van Zuilen, A D; Verhaar, M; Bots, M L; Drop, A C A D; Plaisier, L; Seelen, M A J; Sanders, J S F; Hepkema, B G; Lambeck, A J; Bungener, L B; Roozendaal, C; Tilanus, M G J; Vanderlocht, J; Voorter, C E; Wieten, L; van Duijnhoven, E M; Gelens, M; Christiaans, M H L; van Ittersum, F J; Nurmohamed, A; Lardy, N M; Swelsen, W; van der Pant, K A; van der Weerd, N C; Ten Berge, I J M; Bemelman, F J; Hoitsma, A; van der Boog, P J M; de Fijter, J W; Betjes, M G H; Heidt, S; Roelen, D L; Claas, F H; Otten, H G

2016-09-01

Solid-phase multiplex-bead assays are widely used in transplantation to detect anti-human leukocyte antigen (HLA) antibodies. These assays enable high resolution detection of low levels of HLA antibodies. However, multiplex-bead assays are costly and yield variable measurements that limit the comparison of results between laboratories. In the context of a Dutch national Consortium study we aimed to determine the inter-assay and inter-machine variability of multiplex-bead assays, and we assessed how to reduce the assay reagents costs. Fifteen sera containing a variety of HLA antibodies were used yielding in total 7092 median fluorescence intensities (MFI) values. The inter-assay and inter-machine mean absolute relative differences (MARD) of the screening assay were 12% and 13%, respectively. The single antigen bead (SAB) inter-assay MARD was comparable, but showed a higher lot-to-lot variability. Reduction of screening assay reagents to 50% or 40% of manufacturers' recommendations resulted in MFI values comparable to 100% of the reagents, with an MARD of 12% or 14%, respectively. The MARD of the 50% and 40% SAB assay reagent reductions were 11% and 22%, respectively. From this study, we conclude that the reagents can be reliably reduced at least to 50% of manufacturers' recommendations with virtually no differences in HLA antibody assignments. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Conditioning of carbonaceous material prior to physical beneficiation

DOEpatents

Warzinski, Robert P.; Ruether, John A.

1987-01-01

A carbonaceous material such as coal is conditioned by contact with a supercritical fluid prior to physical beneficiation. The solid feed material is contacted with an organic supercritical fluid such as cyclohexane or methanol at temperatures slightly above the critical temperature and pressures of 1 to 4 times the critical pressure. A minor solute fraction is extracted into critical phase and separated from the solid residuum. The residuum is then processed by physical separation such as by froth flotation or specific gravity separation to recover a substantial fraction thereof with reduced ash content. The solute in supercritical phase can be released by pressure reduction and recombined with the low-ash, carbonaceous material.

Drop dynamics on a thin film: Thin film rupture

NASA Astrophysics Data System (ADS)

Carlson, Andreas; Kim, Pilnam; Stone, Howard A.

2011-11-01

The spreading of a water drop on an oil film that covers a solid substrate is a common event in many industrial processes. We study in experiments the dynamics of a water drop on a thin silicone oil film and quantify its interaction with the solid substrate that supports the film. The oil film becomes unstable and ruptures for solids that are hydrophilic. We determine the ``waiting time,'' the time it takes the water drop to drain the silicone film. This timescale is found to highly depend on how well water wets the solid, illustrating the interplay between intermolecular and hydrodynamic forces in the phenomenon. A phase diagram for the thin film stability is extracted based on waters equilibrium contact angle on the solid, which shows that we can either promote or inhibit de-wetting. As water comes in direct contact with the solid, it spreads and peels off the silicone film. We show the influence of viscosity, equilibrium contact angle and film height on the opening radius of the hole formed as the solid de-wets.

Slip-mediated dewetting of polymer microdroplets

PubMed Central

McGraw, Joshua D.; Chan, Tak Shing; Maurer, Simon; Salez, Thomas; Benzaquen, Michael; Raphaël, Elie; Brinkmann, Martin; Jacobs, Karin

2016-01-01

Classical hydrodynamic models predict that infinite work is required to move a three-phase contact line, defined here as the line where a liquid/vapor interface intersects a solid surface. Assuming a slip boundary condition, in which the liquid slides against the solid, such an unphysical prediction is avoided. In this article, we present the results of experiments in which a contact line moves and where slip is a dominating and controllable factor. Spherical cap-shaped polystyrene microdroplets, with nonequilibrium contact angle, are placed on solid self-assembled monolayer coatings from which they dewet. The relaxation is monitored using in situ atomic force microscopy. We find that slip has a strong influence on the droplet evolutions, both on the transient nonspherical shapes and contact line dynamics. The observations are in agreement with scaling analysis and boundary element numerical integration of the governing Stokes equations, including a Navier slip boundary condition. PMID:26787903

A simple solid phase, peptide-based fluorescent assay for the efficient and universal screening of HRV 3C protease inhibitors.

PubMed

Schünemann, Katrin; Connelly, Stephen; Kowalczyk, Renata; Sperry, Jonathan; Wilson, Ian A; Fraser, John D; Brimble, Margaret A

2012-08-01

With over a 100 different serotypes, the human rhinovirus (HRV) is the major aetiological agent for the common cold, for which only symptomatic treatment is available. HRV maturation and replication is entirely dependent on the activity of a virally encoded 3C protease that represents an attractive target for the development of therapeutics to treat the common cold. Although a variety of small molecules and peptidomimetics have been found to inhibit HRV 3C protease, no universally compatible assay exists to reliably quantify the activity of the enzyme in vitro. Herein we report the development of a universal and robust solid phase peptide assay that utilizes the full HRV-14 3C protease recognition sequence and the release of 5(6)-carboxyfluorescein to sensitively quantify protease activity. This novel assay overcomes several limitations of existing assays allowing for the simple and efficient analysis of HRV-14 3C protease activity facilitating both high-throughput screening and the accurate kinetic study of HRV-14 3C protease inhibitors. Copyright © 2012 Elsevier Ltd. All rights reserved.

Spreading dynamics of 2D dipolar Langmuir monolayer phases.

PubMed

Heinig, P; Wurlitzer, S; Fischer, Th M

2004-07-01

We study the spreading of a liquid 2D dipolar droplet in a Langmuir monolayer. Interfacial tensions (line tensions) and microscopic contact angles depend on the scale on which they are probed and obey a scaling law. Assuming rapid equilibration of the microscopic contact angle and ideal slippage of the 2D solid/liquid and solid/gas boundary, the driving force of spreading is merely expressed by the shape-dependent long-range interaction integrals. We obtain good agreement between experiment and numerical simulations using this theory.

Phase equilibrium modeling for high temperature metallization on GaAs solar cells

NASA Technical Reports Server (NTRS)

Chung, M. A.; Davison, J. E.; Smith, S. R.

1991-01-01

Recent trends in performance specifications and functional requirements have brought about the need for high temperature metallization technology to be developed for survivable DOD space systems and to enhance solar cell reliability. The temperature constitution phase diagrams of selected binary and ternary systems were reviewed to determine the temperature and type of phase transformation present in the alloy systems. Of paramount interest are the liquid-solid and solid-solid transformations. Data are being utilized to aid in the selection of electrical contact materials to gallium arsenide solar cells. Published data on the phase diagrams for binary systems is readily available. However, information for ternary systems is limited. A computer model is being developed which will enable the phase equilibrium predictions for ternary systems where experimental data is lacking.

Solid Electrolytes and Photoelectrolysis

DTIC Science & Technology

1974-12-31

some DC and low-frequency AC measurements are made with molten NaNO, on both sides of the specimen. These molten - salt measurements have been in...transport properties. 1. Im3 phase. A metastable cubic phase of NaSbO, was obtained from high-pressure KSbO, by ion exchange in molten NaNO...sieves. As these latter structures are stabilized by water, they are unsuitable for solid electrolytes that are to be in contact with molten

Synthesis of Ti3AuC2, Ti3Au2C2 and Ti3IrC2 by noble metal substitution reaction in Ti3SiC2 for high-temperature-stable Ohmic contacts to SiC

NASA Astrophysics Data System (ADS)

Fashandi, Hossein; Dahlqvist, Martin; Lu, Jun; Palisaitis, Justinas; Simak, Sergei I.; Abrikosov, Igor A.; Rosen, Johanna; Hultman, Lars; Andersson, Mike; Lloyd Spetz, Anita; Eklund, Per

2017-08-01

The large class of layered ceramics encompasses both van der Waals (vdW) and non-vdW solids. While intercalation of noble metals in vdW solids is known, formation of compounds by incorporation of noble-metal layers in non-vdW layered solids is largely unexplored. Here, we show formation of Ti3AuC2 and Ti3Au2C2 phases with up to 31% lattice swelling by a substitutional solid-state reaction of Au into Ti3SiC2 single-crystal thin films with simultaneous out-diffusion of Si. Ti3IrC2 is subsequently produced by a substitution reaction of Ir for Au in Ti3Au2C2. These phases form Ohmic electrical contacts to SiC and remain stable after 1,000 h of ageing at 600 °C in air. The present results, by combined analytical electron microscopy and ab initio calculations, open avenues for processing of noble-metal-containing layered ceramics that have not been synthesized from elemental sources, along with tunable properties such as stable electrical contacts for high-temperature power electronics or gas sensors.

Innovative design and material solutions of thermal contact layers for high heat flux applications in fusion devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Federici, G.; Matera, R.; Chiocchio, S.

1994-11-01

One difficulty associated with the design and development of sacrificial plasma facing components that have to handle the high heat and particle fluxes in ITER is achieving the necessary contact conductance between the plasma protection material and the high-conductivity substrate in contact with the coolant. This paper presents a novel bond idea which is proposed as one of the options for the sacrificial energy dump targets located at the bottom of the divertor legs. The bonded joint in this design concept provides thermal and electrical contact between the armour and the cooled sub-structure while promoting remote, in-situ maintenance repair andmore » an easy replaceability of the armour part without disturbing the cooling pipes or rewelding neutron irradiated materials. To provide reliable and demountable adhesion, the bond consists of a metal alloy, treated in the semi-solid phase so that it leads to a fine dispersion of a globular solid phase into a liquid matrix (rheocast process). This thermal bond layer would normally operate in the solid state but could be brought reversibly to the semi-solid state during the armour replacement simply by heating it slightly above its solidus temperature. Material and design options are discussed in this paper. Possible methods of installation and removal are described, and lifetime considerations are addressed. In order to validate this concept within the ITER time-frame, a R&D programme must be rapidly implemented.« less

Cellulose-Pectin Spatial Contacts Are Inherent to Never-Dried Arabidopsis Primary Cell Walls: Evidence from Solid-State Nuclear Magnetic Resonance1[OPEN

PubMed Central

Wang, Tuo; Park, Yong Bum; Hong, Mei

2015-01-01

The structural role of pectins in plant primary cell walls is not yet well understood because of the complex and disordered nature of the cell wall polymers. We recently introduced multidimensional solid-state nuclear magnetic resonance spectroscopy to characterize the spatial proximities of wall polysaccharides. The data showed extensive cross peaks between pectins and cellulose in the primary wall of Arabidopsis (Arabidopsis thaliana), indicating subnanometer contacts between the two polysaccharides. This result was unexpected because stable pectin-cellulose interactions are not predicted by in vitro binding assays and prevailing cell wall models. To investigate whether the spatial contacts that give rise to the cross peaks are artifacts of sample preparation, we now compare never-dried Arabidopsis primary walls with dehydrated and rehydrated samples. One-dimensional 13C spectra, two-dimensional 13C-13C correlation spectra, water-polysaccharide correlation spectra, and dynamics data all indicate that the structure, mobility, and intermolecular contacts of the polysaccharides are indistinguishable between never-dried and rehydrated walls. Moreover, a partially depectinated cell wall in which 40% of homogalacturonan is extracted retains cellulose-pectin cross peaks, indicating that the cellulose-pectin contacts are not due to molecular crowding. The cross peaks are observed both at −20°C and at ambient temperature, thus ruling out freezing as a cause of spatial contacts. These results indicate that rhamnogalacturonan I and a portion of homogalacturonan have significant interactions with cellulose microfibrils in the native primary wall. This pectin-cellulose association may be formed during wall biosynthesis and may involve pectin entrapment in or between cellulose microfibrils, which cannot be mimicked by in vitro binding assays. PMID:26036615

Solid catalyzed isoparaffin alkylation at supercritical fluid and near-supercritical fluid conditions

DOEpatents

Ginosar, Daniel M.; Fox, Robert V.; Kong, Peter C.

2000-01-01

This invention relates to an improved method for the alkylation reaction of isoparaffins with olefins over solid catalysts including contacting a mixture of an isoparaffin, an olefin and a phase-modifying material with a solid acid catalyst member under alkylation conversion conditions at either supercritical fluid, or near-supercritical fluid conditions, at a temperature and a pressure relative to the critical temperature(T.sub.c) and the critical pressure(P.sub.c) of the reaction mixture. The phase-modifying phase-modifying material is employed to promote the reaction's achievement of either a supercritical fluid state or a near-supercritical state while simultaneously allowing for decreased reaction temperature and longer catalyst life.

Introducing MINA--The Molecularly Imprinted Nanoparticle Assay.

PubMed

Shutov, Roman V; Guerreiro, Antonio; Moczko, Ewa; de Vargas-Sansalvador, Isabel Perez; Chianella, Iva; Whitcombe, Michael J; Piletsky, Sergey A

2014-03-26

A new ELISA- (enzyme-linked immunosorbent assay)-like assay is demonstrated in which no elements of biological origin are used for molecular recognition or signaling. Composite imprinted nanoparticles that contain a catalytic core and which are synthesized by using a solid-phase approach can simultaneously act as recognition/signaling elements, and be used with minimal modifications to standard assay protocols. This assay provides a new route towards replacement of unstable biomolecules in immunoassays. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quantitative determination of a chemically modified hammerhead ribozyme in blood plasma using 96-well solid-phase extraction coupled with high-performance liquid chromatography or capillary gel electrophoresis.

PubMed

Bellon, L; Maloney, L; Zinnen, S P; Sandberg, J A; Johnson, K E

2000-08-01

Versatile bioanalytical assays to detect chemically stabilized hammerhead ribozyme and putative ribozyme metabolites from plasma are described. The extraction protocols presented are based on serial solid-phase extractions performed on a 96-well plate format and are compatible with either IEX-HPLC or CGE back-end analysis. A validation of both assays confirmed that both the HPLC and the CGE methods possess the required linearity, accuracy, and precision to accurately measure concentrations of hammerhead ribozyme extracted from plasma. These methods should be of general use to detect and quantitate ribozymes from other biological fluids such as serum and urine. Copyright 2000 Academic Press.

Droplets and the three-phase contact line at the nano-scale. Statics and dynamics

NASA Astrophysics Data System (ADS)

Yatsyshin, Petr; Sibley, David; Savva, Nikos; Kalliadasis, Serafim

2014-11-01

Understanding the behaviour of the solid-liquid-vapour contact line at the scale of several tens of molecular diameters is important in wetting hydrodynamics with applications in micro- and nano-fluidics, including the design of lab-on-a-chip devices and surfaces with specific wetting properties. Due to the fluid inhomogeneity at the nano-scale, the application of continuum-mechanical approaches is limited, and a natural way to remedy this is to seek descriptions accounting for the non-local molecular-level interactions. Density Functional Theory (DFT) for fluids offers a statistical-mechanical framework based on expressing the free energy of the fluid-solid pair as a functional of the spatially varying fluid density. DFT allows us to investigate small drops deposited on planar substrates whilst keeping track of the microscopic structural details of the fluid. Starting from a model of intermolecular forces, we systematically obtain interfaces, surface tensions, and the microscopic contact angle. Using a dynamic extension of equilibrium DFT, we investigate the diffusion-driven evolution of the three-phase contact line to gain insight into the dynamic behaviour of the microscopic contact angle, which is still under debate.

Experimental Studies of Adhesion of a Highly Swollen Gel

NASA Astrophysics Data System (ADS)

Cole, Phillip; Emerson, John

2003-03-01

A fracture mechanics methodology based on the Johnson-Kendall-Roberts (JKR) theory is used to quantify the self-adhesion of a highly swollen gel. The solid phase of the gel is a cross-linked polybutadiene and the liquid phase is dibutylphthlate (maximum 60% by weight). In these experiments two nearly identical gel lenses are brought into contact. Bonding and separation of contact is analyzed in terms of the modified JKR theory of Shull [1]. Simultaneous measurements of the applied load, the load point displacement and the contact radius between the lenses allow us to determine the elastic modulus of the gel and the energy release rate. It also allows us to determine whether the observed hysteresis is primarily due to surface dissipation or due to bulk viscoelasticity. The energy release rate is found to be approximately constant during the bonding phase of the experiment. During the debonding phase, the energy release rate increases with the crack velocity or the receding rate of contact radius. Self-adhesion is quantified in the debonding phase through the relationship between the energy release rate and the crack growth rate. The energy release rate during the bonding phase is compared to the surface tension of the liquid and the solid. We also study the effect of liquid phase on the self-adhesion by varying the amount of liquid from zero percent to the maximum of sixty percent. [1] Shull, K. R. Materials Science and Engineering R-Reports, 36 (2002) 1-45. This work was performed at Sandia National Laboratories, supported by the United States Department of Energy under contract number DE-AC04-94AL85000.

Toxicity assessment of diesel- and metal-contaminated soils through elutriate and solid phase assays with the slime mold Dictyostelium discoideum.

PubMed

Rodríguez-Ruiz, Amaia; Dondero, Francesco; Viarengo, Aldo; Marigómez, Ionan

2016-06-01

A suite of organisms from different taxonomical and ecological positions is needed to assess environmentally relevant soil toxicity. A new bioassay based on Dictyostelium is presented that is aimed at integrating slime molds into such a testing framework. Toxicity tests on elutriates and the solid phase developmental cycle assay were successfully applied to a soil spiked with a mixture of Zn, Cd, and diesel fuel freshly prepared (recently contaminated) and after 2 yr of aging. The elutriates of both soils provoked toxic effects, but toxicity was markedly lower in the aged soil. In the D. discoideum developmental cycle assay, both soils affected amoeba viability and aggregation, with fewer multicellular units, smaller fruiting bodies and, overall, inhibition of fruiting body formation. This assay is quick and requires small amounts of test soil, which might facilitate its incorporation into a multispecies multiple-endpoint toxicity bioassay battery suitable for environmental risk assessment in soils. Environ Toxicol Chem 2016;35:1413-1421. © 2015 SETAC. © 2015 SETAC.

Quantitative ionspray liquid chromatographic/tandem mass spectrometric determination of reserpine in equine plasma.

PubMed

Anderson, M A; Wachs, T; Henion, J D

1997-02-01

A method based on ionspray liquid chromatography/tandem mass spectrometry (LC/MS/MS) was developed for the determination of reserpine in equine plasma. A comparison was made of the isolation of reserpine from plasma by liquid-liquid extraction and by solid-phase extraction. A structural analog, rescinnamine, was used as the internal standard. The reconstituted extracts were analyzed by ionspray LC/MS/MS in the selected reaction monitoring (SRM) mode. The calibration graph for reserpine extracted from equine plasma obtained using liquid-liquid extraction was linear from 10 to 5000 pg ml-1 and that using solid-phase extraction from 100 to 5000 pg ml-1. The lower level of quantitation (LLQ) using liquid-liquid and solid-phase extraction was 50 and 200 pg ml-1, respectively. The lower level of detection for reserpine by LC/MS/MS was 10 pg ml-1. The intra-assay accuracy did not exceed 13% for liquid-liquid and 12% for solid-phase extraction. The recoveries for the LLQ were 68% for liquid-liquid and 58% for solid-phase extraction.

Dissolution of aragonite-strontianite solid solutions in nonstoichiometric Sr (HCO3)2-Ca (HCO3)2-CO2-H2O solutions

USGS Publications Warehouse

Plummer, Niel; Busenberg, E.; Glynn, P.D.; Blum, A.E.

1992-01-01

Synthetic strontianite-aragonite solid-solution minerals were dissolved in CO2-saturated non-stoichiometric solutions of Sr(HCO3)2 and Ca(HCO3)2 at 25??C. The results show that none of the dissolution reactions reach thermodynamic equilibrium. Congruent dissolution in Ca(HCO3)2 solutions either attains or closely approaches stoichiometric saturation with respect to the dissolving solid. In Sr(HCO3)2 solutions the reactions usually become incongruent, precipitating a Sr-rich phase before reaching stoichiometric saturation. Dissolution of mechanical mixtures of solids approaches stoichiometric saturation with respect to the least stable solid in the mixture. Surface uptake from subsaturated bulk solutions was observed in the initial minutes of dissolution. This surficial phase is 0-10 atomic layers thick in Sr(HCO3)2 solutions and 0-4 layers thick in Ca(HCO3)2 solutions, and subsequently dissolves and/or recrystallizes, usually within 6 min of reaction. The initial transient surface precipitation (recrystallization) process is followed by congruent dissolution of the original solid which proceeds to stoichiometric saturation, or until the precipitation of a more stable Sr-rich solid. The compositions of secondary precipitates do not correspond to thermodynamic equilibrium or stoichiometric saturation states. X-ray photoelectron spectroscopy (XPS) measurements indicate the formation of solid solutions on surfaces of aragonite and strontianite single crystals immersed in Sr(HCO3)2 and Ca(HCO3)2 solutions, respectively. In Sr(HCO3)2 solutions, the XPS signal from the outer ~ 60 A?? on aragonite indicates a composition of 16 mol% SrCO3 after only 2 min of contact, and 14-18 mol% SrCO3 after 3 weeks of contact. The strontianite surface averages approximately 22 mol% CaCO3 after 2 min of contact with Ca(HCO3)2 solution, and is 34-39 mol% CaCO3 after 3 weeks of contact. XPS analysis suggests the surface composition is zoned with somewhat greater enrichment in the outer ~25 A?? (as much as 26 mol% SrCO3 on aragonite and 44 mol% CaCO3 on strontianite). The results indicate rapid formation of a solid-solution surface phase from subsaturated aqueous solutions. The surface phase continually adjusts in composition in response to changes in composition of the bulk fluid as net dissolution proceeds. Dissolution rates of the endmembers are greatly reduced in nonstoichiometric solutions relative to dissolution rates observed in stoichiometric solutions. All solids dissolve more slowly in solutions spiked with the least soluble component ((Sr(HCO3)2)) than in solutions spiked with the more soluble component (Ca(HCO3)2), an effect that becomes increasingly significant as stoichiometric saturation is approached. It is proposed that the formation of a non-stoichiometric surface reactive zone significantly decreases dissolution rates. ?? 1992.

A three-dimensional phase field model for nanowire growth by the vapor-liquid-solid mechanism

NASA Astrophysics Data System (ADS)

Wang, Yanming; Ryu, Seunghwa; McIntyre, Paul C.; Cai, Wei

2014-07-01

We present a three-dimensional multi-phase field model for catalyzed nanowire (NW) growth by the vapor-liquid-solid (VLS) mechanism. The equation of motion contains both a Ginzburg-Landau term for deposition and a diffusion (Cahn-Hilliard) term for interface relaxation without deposition. Direct deposition from vapor to solid, which competes with NW crystal growth through the molten catalyst droplet, is suppressed by assigning a very small kinetic coefficient at the solid-vapor interface. The thermodynamic self-consistency of the model is demonstrated by its ability to reproduce the equilibrium contact angles at the VLS junction. The incorporation of orientation dependent gradient energy leads to faceting of the solid-liquid and solid-vapor interfaces. The model successfully captures the curved shape of the NW base and the Gibbs-Thomson effect on growth velocity.

A solid-phase assay for studying direct binding of progranulin to TNFR and progranulin antagonism of TNF/TNFR interactions.

PubMed

Tian, Qingyun; Zhao, Shuai; Liu, Chuanju

2014-01-01

The discovery that TNF receptors (TNFR) serve as the binding receptors for progranulin (PGRN) reveals the significant role of PGRN in inflammatory and autoimmune diseases, including inflammatory arthritis. Herein we describe a simple, antibody-free analytical assay, i.e., a biotin-based solid-phase binding assay, to examine the direct interaction of PGRN/TNFR and the PGRN inhibition of TNF/TNFR interactions. Briefly, a 96-well high-binding microplate is first coated with the first protein (protein A), and after blocking, the coated microplate is incubated with the biotin-labeled second protein (protein B) in the absence or presence of the third protein (protein C). Finally the streptavidin conjugated with a detecting enzyme is added, followed by a signal measurement. Also discussed in this chapter are the advantages of the strategy, key elements to obtain reliable results, and discrepancies among various PGRN proteins in view of the binding activity with TNFR.

Determining solid-fluid interface temperature distribution during phase change of cryogenic propellants using transient thermal modeling

NASA Astrophysics Data System (ADS)

Bellur, K.; Médici, E. F.; Hermanson, J. C.; Choi, C. K.; Allen, J. S.

2018-04-01

Control of boil-off of cryogenic propellants is a continuing technical challenge for long duration space missions. Predicting phase change rates of cryogenic liquids requires an accurate estimation of solid-fluid interface temperature distributions in regions where a contact line or a thin liquid film exists. This paper described a methodology to predict inner wall temperature gradients with and without evaporation using discrete temperature measurements on the outer wall of a container. Phase change experiments with liquid hydrogen and methane in cylindrical test cells of various materials and sizes were conducted at the Neutron Imaging Facility at the National Institute of Standards and Technology. Two types of tests were conducted. The first type of testing involved thermal cycling of an evacuated cell (dry) and the second involved controlled phase change with cryogenic liquids (wet). During both types of tests, temperatures were measured using Si-diode sensors mounted on the exterior surface of the test cells. Heat is transferred to the test cell by conduction through a helium exchange gas and through the cryostat sample holder. Thermal conduction through the sample holder is shown to be the dominant mode with the rate of heat transfer limited by six independent contact resistances. An iterative methodology is employed to determine contact resistances between the various components of the cryostat stick insert, test cell and lid using the dry test data. After the contact resistances are established, inner wall temperature distributions during wet tests are calculated.

Qualitative numerical study of simultaneous high-G-intensified gas–solids contact, separation and segregation in a bi-disperse rotating fluidized bed in a vortex chamber

DOE PAGES

De Wilde, Juray; Richards, George; Benyahia, Sofiane

2016-05-13

Coupled discrete particle method – computational fluid dynamics simulations are carried out to demonstrate the potential of combined high-G-intensified gas-solids contact, gas-solids separation and segregation in a rotating fluidized bed in a static vortex chamber. A case study with two distinct types of particles is focused on. When feeding solids using a standard solids inlet design, a dense and uniform rotating fluidized bed is formed, guaranteeing intense gas-solids contact. The presence of both types of particles near the chimney region reduces, however, the strength of the central vortex and is detrimental for separation and segregation. Optimization of the solids inletmore » design is required, as illustrated by stopping the solids feeding. High-G separation and segregation of the batch of particles is demonstrated, as the strength of the central vortex is restored. The flexibility with respect to the gas flow rate of the bed density and uniformity and of the gas-solids separation and segregation is demonstrated, a unique feature of vortex chamber generated rotating fluidized beds. With the particles considered in this case study, turbulent dispersion by large eddies in the gas phase is shown to have only a minor impact on the height of the inner bed of small/light particles.« less

Apparatus for photon excited catalysis

NASA Technical Reports Server (NTRS)

Saffren, M. M. (Inventor)

1977-01-01

An apparatus is described for increasing the yield of photonically excited gas phase reactions by extracting excess energy from unstable, excited species by contacting the species with the surface of a finely divided solid.

Design and fabrication of highly hydrophobic Mn nano-sculptured thin films and evaluation of surface properties on hydrophobicity

NASA Astrophysics Data System (ADS)

Hosseini, Somaye; Savaloni, Hadi; Gholipour-Shahraki, Mehran

2017-03-01

The wettability of solid surfaces is important from the aspects of both science and technology. The Mn nano-sculptured thin films were designed and fabricated by oblique angle deposition of Mn on glass substrates at room temperature. The obtained structure was characterized by field emission scanning electron microscopy and atomic force microscopy. The wettability of thin films samples was investigated by water contact angle (WCA). The 4-pointed helical star-shaped structure exhibits hydrophobicity with static WCAs of more than 133° for a 10-mg distilled water droplet. This sample also shows the rose petal effect with the additional property of high adhesion. The Mn nano-sculptured thin films also act as a sticky surface which is confirmed by hysteresis of the contact angle obtained from advancing and receding contact angles measurements. Physicochemical property of liquid phase could effectively change the contact angle, and polar solvents in contact with hydrophobic solid surfaces do not necessarily show high contact angle value.

Ultrasensitive microfluidic solid-phase ELISA using an actuatable microwell-patterned PDMS chip.

PubMed

Wang, Tanyu; Zhang, Mohan; Dreher, Dakota D; Zeng, Yong

2013-11-07

Quantitative detection of low abundance proteins is of significant interest for biological and clinical applications. Here we report an integrated microfluidic solid-phase ELISA platform for rapid and ultrasensitive detection of proteins with a wide dynamic range. Compared to the existing microfluidic devices that perform affinity capture and enzyme-based optical detection in a constant channel volume, the key novelty of our design is two-fold. First, our system integrates a microwell-patterned assay chamber that can be pneumatically actuated to significantly reduce the volume of chemifluorescent reaction, markedly improving the sensitivity and speed of ELISA. Second, monolithic integration of on-chip pumps and the actuatable assay chamber allow programmable fluid delivery and effective mixing for rapid and sensitive immunoassays. Ultrasensitive microfluidic ELISA was demonstrated for insulin-like growth factor 1 receptor (IGF-1R) across at least five orders of magnitude with an extremely low detection limit of 21.8 aM. The microwell-based solid-phase ELISA strategy provides an expandable platform for developing the next-generation microfluidic immunoassay systems that integrate and automate digital and analog measurements to further improve the sensitivity, dynamic ranges, and reproducibility of proteomic analysis.

Process for separating and recovering an anionic dye from an aqueous solution

DOEpatents

Rogers, Robin; Horwitz, E. Philip; Bond, Andrew H.

1998-01-01

A solid/liquid phase process for the separation and recovery of an anionic dye from an aqueous solution is disclosed. The solid phase comprises separation particles having surface-bonded poly(ethylene glycol) groups, whereas the aqueous solution from which the anionic dye molecules are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt. After contact between the aqueous solution and separation particles, the anionic dye is bound to the particles. The bound anionic dye molecules are freed from the separation particles by contacting the anionic dye-bound particles with an aqueous solution that does not contain a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt to form an aqueous anionic dye solution whose anionic dye concentration is preferably higher than that of the initial dye-containing solution.

Local solid phase growth of few-layer graphene on silicon carbide from nickel silicide supersaturated with carbon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Escobedo-Cousin, Enrique; Vassilevski, Konstantin; Hopf, Toby

Patterned few-layer graphene (FLG) films were obtained by local solid phase growth from nickel silicide supersaturated with carbon, following a fabrication scheme, which allows the formation of self-aligned ohmic contacts on FLG and is compatible with conventional SiC device processing methods. The process was realised by the deposition and patterning of thin Ni films on semi-insulating 6H-SiC wafers followed by annealing and the selective removal of the resulting nickel silicide by wet chemistry. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to confirm both the formation and subsequent removal of nickel silicide. The impact of process parameters such asmore » the thickness of the initial Ni layer, annealing temperature, and cooling rates on the FLG films was assessed by Raman spectroscopy, XPS, and atomic force microscopy. The thickness of the final FLG film estimated from the Raman spectra varied from 1 to 4 monolayers for initial Ni layers between 3 and 20 nm thick. Self-aligned contacts were formed on these patterned films by contact photolithography and wet etching of nickel silicide, which enabled the fabrication of test structures to measure the carrier concentration and mobility in the FLG films. A simple model of diffusion-driven solid phase chemical reaction was used to explain formation of the FLG film at the interface between nickel silicide and silicon carbide.« less

Fatty Acid-binding Proteins Interact with Comparative Gene Identification-58 Linking Lipolysis with Lipid Ligand Shuttling*

PubMed Central

Hofer, Peter; Boeszoermenyi, Andras; Jaeger, Doris; Feiler, Ursula; Arthanari, Haribabu; Mayer, Nicole; Zehender, Fabian; Rechberger, Gerald; Oberer, Monika; Zimmermann, Robert; Lass, Achim; Haemmerle, Guenter; Breinbauer, Rolf; Zechner, Rudolf; Preiss-Landl, Karina

2015-01-01

The coordinated breakdown of intracellular triglyceride (TG) stores requires the exquisitely regulated interaction of lipolytic enzymes with regulatory, accessory, and scaffolding proteins. Together they form a dynamic multiprotein network designated as the “lipolysome.” Adipose triglyceride lipase (Atgl) catalyzes the initiating step of TG hydrolysis and requires comparative gene identification-58 (Cgi-58) as a potent activator of enzyme activity. Here, we identify adipocyte-type fatty acid-binding protein (A-Fabp) and other members of the fatty acid-binding protein (Fabp) family as interaction partners of Cgi-58. Co-immunoprecipitation, microscale thermophoresis, and solid phase assays proved direct protein/protein interaction between A-Fabp and Cgi-58. Using nuclear magnetic resonance titration experiments and site-directed mutagenesis, we located a potential contact region on A-Fabp. In functional terms, A-Fabp stimulates Atgl-catalyzed TG hydrolysis in a Cgi-58-dependent manner. Additionally, transcriptional transactivation assays with a luciferase reporter system revealed that Fabps enhance the ability of Atgl/Cgi-58-mediated lipolysis to induce the activity of peroxisome proliferator-activated receptors. Our studies identify Fabps as crucial structural and functional components of the lipolysome. PMID:25953897

A comparison of the performance of molecularly imprinted polymer nanoparticles for small molecule targets and antibodies in the ELISA format

NASA Astrophysics Data System (ADS)

Smolinska-Kempisty, Katarzyna; Guerreiro, Antonio; Canfarotta, Francesco; Cáceres, César; Whitcombe, Michael J.; Piletsky, Sergey

2016-11-01

Here we show that molecularly imprinted polymer nanoparticles, prepared in aqueous media by solid phase synthesis with immobilised L-thyroxine, glucosamine, fumonisin B2 or biotin as template, can demonstrate comparable or better performance to commercially produced antibodies in enzyme-linked competitive assays. Imprinted nanoparticles-based assays showed detection limits in the pM range and polymer-coated microplates are stable to storage at room temperature for at least 1 month. No response to analyte was detected in control experiments with nanoparticles imprinted with an unrelated template (trypsin) but prepared with the same polymer composition. The ease of preparation, high affinity of solid-phase synthesised imprinted nanoparticles and the lack of requirement for cold chain logistics make them an attractive alternative to traditional antibodies for use in immunoassays.

A comparison of the performance of molecularly imprinted polymer nanoparticles for small molecule targets and antibodies in the ELISA format.

PubMed

Smolinska-Kempisty, Katarzyna; Guerreiro, Antonio; Canfarotta, Francesco; Cáceres, César; Whitcombe, Michael J; Piletsky, Sergey

2016-11-24

Here we show that molecularly imprinted polymer nanoparticles, prepared in aqueous media by solid phase synthesis with immobilised L-thyroxine, glucosamine, fumonisin B2 or biotin as template, can demonstrate comparable or better performance to commercially produced antibodies in enzyme-linked competitive assays. Imprinted nanoparticles-based assays showed detection limits in the pM range and polymer-coated microplates are stable to storage at room temperature for at least 1 month. No response to analyte was detected in control experiments with nanoparticles imprinted with an unrelated template (trypsin) but prepared with the same polymer composition. The ease of preparation, high affinity of solid-phase synthesised imprinted nanoparticles and the lack of requirement for cold chain logistics make them an attractive alternative to traditional antibodies for use in immunoassays.

A comparison of the performance of molecularly imprinted polymer nanoparticles for small molecule targets and antibodies in the ELISA format

PubMed Central

Smolinska-Kempisty, Katarzyna; Guerreiro, Antonio; Canfarotta, Francesco; Cáceres, César; Whitcombe, Michael J.; Piletsky, Sergey

2016-01-01

Here we show that molecularly imprinted polymer nanoparticles, prepared in aqueous media by solid phase synthesis with immobilised L-thyroxine, glucosamine, fumonisin B2 or biotin as template, can demonstrate comparable or better performance to commercially produced antibodies in enzyme-linked competitive assays. Imprinted nanoparticles-based assays showed detection limits in the pM range and polymer-coated microplates are stable to storage at room temperature for at least 1 month. No response to analyte was detected in control experiments with nanoparticles imprinted with an unrelated template (trypsin) but prepared with the same polymer composition. The ease of preparation, high affinity of solid-phase synthesised imprinted nanoparticles and the lack of requirement for cold chain logistics make them an attractive alternative to traditional antibodies for use in immunoassays. PMID:27883023

Stability of the solid electrolyte Li{sub 3}OBr to common battery solvents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schroeder, D.J.; Hubaud, A.A.; Vaughey, J.T., E-mail: vaughey@anl.gov

2014-01-01

Graphical abstract: The stability of the anti-perovskite phase Li{sub 3}OBr has been assessed in a variety of battery solvents. - Highlights: • Lithium stable solid electrolyte Li{sub 3}OBr unstable to polar organic solvents. • Solvation with no dissolution destroys long-range structure. • Ion exchange with protons observed. - Abstract: Recently a new class of solid lithium ion conductors was reported based on the anti-perovskite structure, notably Li{sub 3}OCl and Li{sub 3}OBr. For many beyond lithium-ion battery uses, the solid electrolyte is envisioned to be in direct contact with liquid electrolytes and lithium metal. In this study we evaluated the stabilitymore » of the Li{sub 3}OBr phase against common battery solvents electrolytes, including diethylcarbonate (DEC) and dimethylcarbonate (DMC), as well as a LiPF{sub 6} containing commercial electrolyte. In contact with battery-grade organic solvents, Li{sub 3}OBr was typically found to be insoluble but lost its crystallinity and reacted with available protons and in some cases with the solvent. A low temperature heat treatment was able to restore crystallinity of the samples; however evidence of proton ion exchange was conserved.« less

Contact line motion over substrates with spatially non-uniform properties

NASA Astrophysics Data System (ADS)

Ajaev, Vladimir; Gatapova, Elizaveta; Kabov, Oleg

2017-11-01

We develop mathematical models of moving contact lines over flat solid surfaces with spatial variation of temperature and wetting properties under the conditions when evaporation is significant. The gas phase is assumed to be pure vapor and a lubrication-type framework is employed for describing viscous flow in the liquid. Marangoni stresses at the liquid surface arise as a result of temperature variation in the vapor phase, non-equilibrium effects during evaporation at the interface, and Kelvin effect. The relative importance of these three factors is determined. Variation of wetting properties is modeled through a two-component disjoining pressure, with the main focus on spatially periodic patterns leading to time-periodic variation of the contact line speed.

Control of disinfection by-products in canned vegetables caused by water used in their processing.

PubMed

Cardador, Maria Jose; Gallego, Mercedes

2017-01-01

Canned vegetables come into contact with sanitizers and/or treated water in industry during several steps (namely washing, sanitising, blanching and filling with sauces or brine solutions) and therefore they can contain disinfection by-products - DBPs). This study focused on the occurrence of trihalomethanes (THMs) and haloacetic acids (HAAs) in a wide variety of canned vegetables (75 samples). For each vegetable, the edible solid and liquid phases of the package were separated and analysed individually. DBPs can be present in both solid (up to eight species) and liquid (up to 11 species) phases, their levels being higher in liquid ones. Volatile THMs predominate in the edible solid phase (up to four species), while HAAs do so in the liquid phase (up to five species) according to their ionic and non-volatile nature. The lowest concentrations of DBPs were found in tomatoes because they were often preserved in their own juice, without water.

Numerical analysis of deposition frequency for successive droplets coalescence dynamics

NASA Astrophysics Data System (ADS)

Cheng, Xiaoding; Zhu, Yunlong; Zhang, Lei; Zhang, Dingyi; Ku, Tao

2018-04-01

A pseudopotential based multi-relaxation-time lattice Boltzmann model is employed to investigate the dynamic behaviors of successive droplets' impact and coalescence on a solid surface. The effects of deposition frequency on the morphology of the formed line are investigated with a zero receding contact angle by analyzing the droplet-to-droplet coalescence dynamics. Two collision modes (in-phase mode and out-of-phase mode) between the pre-deposited bead and the subsequent droplet are identified depending on the deposition frequency. A uniform line can be obtained at the optimal droplet spacing in the in-phase mode (Δt* < 1.875). However, a scalloped line pattern is formed in the out-of-phase mode (Δt* > 1.875). It is found that decreasing the droplet spacing or advancing contact angle can improve the smoothness of line in the out-of-phase mode. Furthermore, the effects of deposition frequency on the morphology of the formed lines are validated to be applicable to cases with a finite receding contact angle.

VOF simulations of the contact angle dynamics during the drop spreading: standard models and a new wetting force model.

PubMed

Malgarinos, Ilias; Nikolopoulos, Nikolaos; Marengo, Marco; Antonini, Carlo; Gavaises, Manolis

2014-10-01

In this study,a novel numerical implementation for the adhesion of liquid droplets impacting normally on solid dry surfaces is presented. The advantage of this new approach, compared to the majority of existing models, is that the dynamic contact angle forming during the surface wetting process is not inserted as a boundary condition, but is derived implicitly by the induced fluid flow characteristics (interface shape) and the adhesion physics of the gas-liquid-surface interface (triple line), starting only from the advancing and receding equilibrium contact angles. These angles are required in order to define the wetting properties of liquid phases when interacting with a solid surface. The physical model is implemented as a source term in the momentum equation of a Navier-Stokes CFD flow solver as an "adhesion-like" force which acts at the triple-phase contact line as a result of capillary interactions between the liquid drop and the solid substrate. The numerical simulations capture the liquid-air interface movement by considering the volume of fluid (VOF) method and utilizing an automatic local grid refinement technique in order to increase the accuracy of the predictions at the area of interest, and simultaneously minimize numerical diffusion of the interface. The proposed model is validated against previously reported experimental data of normal impingement of water droplets on dry surfaces at room temperature. A wide range of impact velocities, i.e. Weber numbers from as low as 0.2 up to 117, both for hydrophilic (θadv=10°-70°) and hydrophobic (θadv=105°-120°) surfaces, has been examined. Predictions include in addition to droplet spreading dynamics, the estimation of the dynamic contact angle; the latter is found in reasonable agreement against available experimental measurements. It is thus concluded that theimplementation of this model is an effective approach for overcoming the need of a pre-defined dynamic contact angle law, frequently adopted as an approximate boundary condition for such simulations. Clearly, this model is mostly influential during the spreading phase for the cases of low We number impacts (We<˜80) since for high impact velocities, inertia dominates significantly over capillary forces in the initial phase of spreading. Copyright © 2014 Elsevier B.V. All rights reserved.

Growth and analysis of gallium arsenide-gallium antimonide single and two-phase nanoparticles

NASA Astrophysics Data System (ADS)

Schamp, Crispin T.

When evaluating the path of phase transformations in systems with nanoscopic dimensions one often relies on bulk phase diagrams for guidance because of the lack of phase diagrams that show the effect of particle size. The GaAs-GaSb pseudo-binary alloy is chosen for study to gain insight into the size dependence of solid-solubility in a two-phase system. To this end, a study is performed using independent laser ablation of high purity targets of GaAs and GaSb. The resultant samples are analyzed by transmission electron microscopy. Experimental results indicate that GaAs-GaSb nanoparticles have been formed with compositions that lie within the miscibility gap of bulk GaAs-GaSb. An unusual nanoparticle morpohology resembling the appearance of ice cream cones has been observed in single component experiments. These particles are composed of a spherical cap of Ga in contact with a crystalline cone of either GaAs or GaSb. The cones take the projected 2-D shape of a triangle or a faceted gem. The liquid Ga is found to consistently be of spherical shape and wets to the widest corners of the cone, suggesting an energy minimum exists at that wetting condition. To explore this observation a liquid sphere is modeled as being penetrated by a solid gem. The surface energies of the solid and liquid, and interfacial energy are summed as a function of penetration depth, with the sum showing a cusped minimum at the penetration depth corresponding to the waist of the gem. The angle of contact of the liquid wetting the cone is also calculated, and Young's contact angle is found to occur when the derivative of the total energy with respect to penetration depth is zero, which can be a maximum or a minimum depending on the geometrical details. The spill-over of the meniscus across the gem corners is found to be energetically favorable when the contact angle achieves the value of the equilibrium angle; otherwise the meniscus is pinned at the corners.

Phase development in a U-7 wt.% Mo vs. Al-7 wt.% Ge diffusion couple

NASA Astrophysics Data System (ADS)

Perez, E.; Keiser, D. D.; Sohn, Y. H.

2013-10-01

Fuel development for the Reduced Enrichment for Research and Test Reactors (RERTR) program has demonstrated that U-Mo alloys in contact with Al develop interaction regions with phases that have poor irradiation behavior. The addition of Si to the Al has been considered with positive results. In this study, compositional modification is considered by replacing Si with Ge to determine the effect on the phase development in the system. The microstructural and phase development of a diffusion couple of U-7 wt.% Mo in contact with Al-7 wt.% Ge was examined by transmission electron microscopy, scanning electron microscopy and energy dispersive spectroscopy. The interdiffusion zone developed a microstructure that included the cubic-UGe3 phase and amorphous phases. The UGe3 phase was observed with and without Mo and Al solid solution developing a (U,Mo)(Al,Ge)3 phase.

Process for separating and recovering an anionic dye from an aqueous solution

DOEpatents

Rogers, R.; Horwitz, E.P.; Bond, A.H.

1998-01-13

A solid/liquid phase process for the separation and recovery of an anionic dye from an aqueous solution is disclosed. The solid phase comprises separation particles having surface-bonded poly(ethylene glycol) groups, whereas the aqueous solution from which the anionic dye molecules are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt. After contact between the aqueous solution and separation particles, the anionic dye is bound to the particles. The bound anionic dye molecules are freed from the separation particles by contacting the anionic dye-bound particles with an aqueous solution that does not contain a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt to form an aqueous anionic dye solution whose anionic dye concentration is preferably higher than that of the initial dye-containing solution. 7 figs.

Superamphiphobic Silicon-Nanowire-Embedded Microsystem and In-Contact Flow Performance of Gas and Liquid Streams.

PubMed

Ko, Dong-Hyeon; Ren, Wurong; Kim, Jin-Oh; Wang, Jun; Wang, Hao; Sharma, Siddharth; Faustini, Marco; Kim, Dong-Pyo

2016-01-26

Gas and liquid streams are invariably separated either by a solid wall or by a membrane for heat or mass transfer between the gas and liquid streams. Without the separating wall, the gas phase is present as bubbles in liquid or, in a microsystem, as gas plugs between slugs of liquid. Continuous and direct contact between the two moving streams of gas and liquid is quite an efficient way of achieving heat or mass transfer between the two phases. Here, we report a silicon nanowire built-in microsystem in which a liquid stream flows in contact with an underlying gas stream. The upper liquid stream does not penetrate into the lower gas stream due to the superamphiphobic nature of the silicon nanowires built into the bottom wall, thereby preserving the integrity of continuous gas and liquid streams, although they are flowing in contact. Due to the superamphiphobic nature of silicon nanowires, the microsystem provides the best possible interfacial mass transfer known to date between flowing gas and liquid phases, which can achieve excellent chemical performance in two-phase organic syntheses.

Preparation of milk samples for immunoassay and liquid chromatographic screening using matrix solid-phase dispersion.

PubMed

Barker, S A; Long, A R

1994-01-01

The use of drugs to maintain the health and maximize the output of dairy cattle has made the monitoring of milk for such agents essential. Screening tests based on immunological, microbial inhibition, and bacterial receptor assays have been developed for the detection of violative levels of therapeutic substances. However, such assays are not infallible, and false positive or negative results can occur when contaminants bind receptors or compete for the binding of the target residues. Such effects may arise from dietary sources, diseases, or other variables. Thus, a violation by such a test is not definitive until further confirmation is obtained. Our laboratory has developed extraction procedures for several drugs used in dairy production. Our method uses matrix solid-phase dispersion (MSPD) to isolate drugs away from contaminants and to eliminate many possible interferences. MSPD can also be used to enhance the specificity of such assays by fractionating various classes of drugs that may cross-react. Similarly, such methods may be used for liquid chromatographic screening and confirmation of a suspect sample.

Super-sensitive time-resolved fluoroimmunoassay for thyroid-stimulating hormone utilizing europium(III) nanoparticle labels achieved by protein corona stabilization, short binding time, and serum preprocessing.

PubMed

Näreoja, Tuomas; Rosenholm, Jessica M; Lamminmäki, Urpo; Hänninen, Pekka E

2017-05-01

Thyrotropin or thyroid-stimulating hormone (TSH) is used as a marker for thyroid function. More precise and more sensitive immunoassays are needed to facilitate continuous monitoring of thyroid dysfunctions and to assess the efficacy of the selected therapy and dosage of medication. Moreover, most thyroid diseases are autoimmune diseases making TSH assays very prone to immunoassay interferences due to autoantibodies in the sample matrix. We have developed a super-sensitive TSH immunoassay utilizing nanoparticle labels with a detection limit of 60 nU L -1 in preprocessed serum samples by reducing nonspecific binding. The developed preprocessing step by affinity purification removed interfering compounds and improved the recovery of spiked TSH from serum. The sensitivity enhancement was achieved by stabilization of the protein corona of the nanoparticle bioconjugates and a spot-coated configuration of the active solid-phase that reduced sedimentation of the nanoparticle bioconjugates and their contact time with antibody-coated solid phase, thus making use of the higher association rate of specific binding due to high avidity nanoparticle bioconjugates. Graphical Abstract We were able to decrease the lowest limit of detection and increase sensitivity of TSH immunoassay using Eu(III)-nanoparticles. The improvement was achieved by decreasing binding time of nanoparticle bioconjugates by small capture area and fast circular rotation. Also, we applied a step to stabilize protein corona of the nanoparticles and a serum-preprocessing step with a structurally related antibody.

Potentiometric Aptasensing of Vibrio alginolyticus Based on DNA Nanostructure-Modified Magnetic Beads.

PubMed

Zhao, Guangtao; Ding, Jiawang; Yu, Han; Yin, Tanji; Qin, Wei

2016-12-02

A potentiometric aptasensing assay that couples the DNA nanostructure-modified magnetic beads with a solid-contact polycation-sensitive membrane electrode for the detection of Vibrio alginolyticus is herein described. The DNA nanostructure-modified magnetic beads are used for amplification of the potential response and elimination of the interfering effect from a complex sample matrix. The solid-contact polycation-sensitive membrane electrode using protamine as an indicator is employed to chronopotentiometrically detect the change in the charge or DNA concentration on the magnetic beads, which is induced by the interaction between Vibrio alginolyticus and the aptamer on the DNA nanostructures. The present potentiometric aptasensing method shows a linear range of 10-100 CFU mL -1 with a detection limit of 10 CFU mL -1 , and a good specificity for the detection of Vibrio alginolyticus . This proposed strategy can be used for the detection of other microorganisms by changing the aptamers in the DNA nanostructures.

Characterization of rhamnolipids by liquid chromatography/mass spectrometry after solid-phase extraction.

PubMed

Behrens, Beate; Engelen, Jeannine; Tiso, Till; Blank, Lars Mathias; Hayen, Heiko

2016-04-01

Rhamnolipids are surface-active agents with a broad application potential that are produced in complex mixtures by bacteria of the genus Pseudomonas. Analysis from fermentation broth is often characterized by laborious sample preparation and requires hyphenated analytical techniques like liquid chromatography coupled to mass spectrometry (LC-MS) to obtain detailed information about sample composition. In this study, an analytical procedure based on chromatographic method development and characterization of rhamnolipid sample material by LC-MS as well as a comparison of two sample preparation methods, i.e., liquid-liquid extraction and solid-phase extraction, is presented. Efficient separation was achieved under reversed-phase conditions using a mixed propylphenyl and octadecylsilyl-modified silica gel stationary phase. LC-MS/MS analysis of a supernatant from Pseudomonas putida strain KT2440 pVLT33_rhlABC grown on glucose as sole carbon source and purified by solid-phase extraction revealed a total of 20 congeners of di-rhamnolipids, mono-rhamnolipids, and their biosynthetic precursors 3-(3-hydroxyalkanoyloxy)alkanoic acids (HAAs) with different carbon chain lengths from C8 to C14, including three rhamnolipids with uncommon C9 and C11 fatty acid residues. LC-MS and the orcinol assay were used to evaluate the developed solid-phase extraction method in comparison with the established liquid-liquid extraction. Solid-phase extraction exhibited higher yields and reproducibility as well as lower experimental effort.

Criteria for the selection of a solid phase to be used in immunoassays.

PubMed

Delagneau, J F; Masseyeff, R

1990-01-01

Heterogeneous immunoassays are very sensitive and only limited in terms of performance by non specific binding. They require separation of free from bound fractions and concomitant use of a solid phase coated with an immunoreactive component (i.e. immunosorbent). The improvement of these key immunosorbents is crucial and involves a great deal of expertise and capabilities. Specifications differ according to procedure (e.g. capture or competitive assay). Each routinely used solid phase, such as polystyrene wells, porous membrane or dispersible microbeads, presents specific performance characteristics, advantages, and drawbacks. Among the tasks to be implemented are optimization of the spatial orientation of immunological reagents, selection of the surface neutral hydrophilic support, acceleration of reactions by increasing the reactive surface area of the supports, streamlining and simplification of procedural steps. These various aspects are abundantly described and emphasized here.

Determination of cocaine, benzoylecgonine and cocaethylene in human hair by solid-phase microextraction and gas chromatography-mass spectrometry.

PubMed

de Toledo, Fernanda Crossi Pereira; Yonamine, Mauricio; de Moraes Moreau, Regina Lucia; Silva, Ovandir Alves

2003-12-25

The present work describes a highly precise and sensitive method developed to detect cocaine (COC), benzoylecgonine (BE, its main metabolite) and cocaethylene (CE, transesterification product of the coingestion of COC with ethanol) in human head hair samples. The method was based on an alkylchloroformate derivatization of benzoylecgonine and the extraction of the analytes by solid-phase microextraction (SPME). Gas chromatography-mass spectrometry (GC-MS) was used to identify and quantify the analytes in selected ion monitoring mode (SIM). The limits of quantification and detection (LOQ and LOD) were: 0.1 ng/mg for COC and CE, and 0.5 ng/mg for BE. Good inter- and intra-assay precision was observed. The dynamic range of the assay was 0.1-50 ng/mg. The method is not time consuming and was shown to be easy to perform.

Quantitation of (R)- and (S)-linalool in beer using solid phase microextraction (SPME) in combination with a stable isotope dilution assay (SIDA).

PubMed

Steinhaus, Martin; Fritsch, Helge T; Schieberle, Peter

2003-11-19

A stable isotope dilution assay (SIDA) was developed for the quantitation of both linalool enantiomers using synthesized [2H(2)]R/S-linalool as the internal standard. For enrichment of the target compound from beer, a solid phase microextraction method (SPME) was developed. In comparison to the more time-consuming extraction/distillation cleanup of the beer samples, the results obtained by SPME/SIDA were very similar, even under nonequilibration conditions. Analysis of five different types of beer showed significant differences in the linalool concentrations, which were clearly correlated with the intensity of the hoppy aroma note as evaluated by a sensory panel. In addition, significant differences in the R/S ratios were measured in the beers. The SPME/SIDA yielded exact data independently from headspace sampling parameters, such as exposure time or ionic strength of the solution.

Improved formula for continuous-wave measurements of ultrasonic phase velocity

NASA Technical Reports Server (NTRS)

Chern, E. J.; Cantrell, J. H., Jr.; Heyman, J. S.

1981-01-01

An improved formula for continuous-wave ultrasonic phase velocity measurements using contact transducers is derived from the transmission line theory. The effect of transducer-sample coupling bonds is considered for measurements of solid samples even though it is often neglected because of the difficulty of accurately determining the bond thickness. Computer models show that the present formula is more accurate than previous expressions. Laboratory measurements using contacting transducers with the present formula are compared to measurements using noncontacting (hence effectively correction-free) capacitive transducers. The results of the experiments verify the validity and accuracy of the new formula.

Rapid solid-phase immunoassay for 6-keto prostaglandin F1 alpha on microplates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schramm, W.; Smith, R.H.; Jackson, T.M.

1990-03-01

We describe, for the measurement of 6-keto prostaglandin F1 alpha in biological media, a solid-phase immunoassay with immobilized antibodies that requires a total processing time of less than 2 h with hands-on time less than 30 min for 40 samples. The method combines the convenience of the microplate format with the sensitivity of radiolabeled prostaglandin derivatives as tracers in a competitive immunoassay. The intra- and interassay variations at 50% displacement of the radiolabeled prostaglandin derivative as tracer were 9.0% and 11.8%, respectively. At 50% displacement of the radiolabeled tracer, the sensitivity is about 20 pg per well. Optimal incubation timemore » is between 60 and 90 min. Nonspecific binding was less than 1% if about 8 pg of tracer (approximately 25,000 counts/min per well) was used. Inhibition curves of samples in different dilutions were parallel to standard curves. The variation of bound radiolabeled prostaglandin derivative within the wells of one microplate (n = 96) was less than 3%. Human plasma samples and medium from tissue culture assayed for 6-keto prostaglandin F1 alpha correlated well with results obtained with a solid-phase assay based on use of magnetic particles (r = 0.99, n = 24) for culture-medium samples; r = 0.99; n = 26 for plasma samples.« less

Optimization of multiplexed PCR on an integrated microfluidic forensic platform for rapid DNA analysis.

PubMed

Estes, Matthew D; Yang, Jianing; Duane, Brett; Smith, Stan; Brooks, Carla; Nordquist, Alan; Zenhausern, Frederic

2012-12-07

This study reports the design, prototyping, and assay development of multiplexed polymerase chain reaction (PCR) on a plastic microfluidic device. Amplification of 17 DNA loci is carried out directly on-chip as part of a system for continuous workflow processing from sample preparation (SP) to capillary electrophoresis (CE). For enhanced performance of on-chip PCR amplification, improved control systems have been developed making use of customized Peltier assemblies, valve actuators, software, and amplification chemistry protocols. Multiple enhancements to the microfluidic chip design have been enacted to improve the reliability of sample delivery through the various on-chip modules. This work has been enabled by the encapsulation of PCR reagents into a solid phase material through an optimized Solid Phase Encapsulating Assay Mix (SPEAM) bead-based hydrogel fabrication process. SPEAM bead technology is reliably coupled with precise microfluidic metering and dispensing for efficient amplification and subsequent DNA short tandem repeat (STR) fragment analysis. This provides a means of on-chip reagent storage suitable for microfluidic automation, with the long shelf-life necessary for point-of-care (POC) or field deployable applications. This paper reports the first high quality 17-plex forensic STR amplification from a reference sample in a microfluidic chip with preloaded solid phase reagents, that is designed for integration with up and downstream processing.

Surface charge-induced EDL interaction on the contact angle of surface nanobubbles.

PubMed

Jing, Dalei; Li, Dayong; Pan, Yunlu; Bhushan, Bharat

2016-11-01

The contact angle (CA) of surface nanobubbles is believed to affect the stability of nanobubbles and fluid drag in micro/nanofluidic systems. The CA of nanobubbles is dependent on size and is believed to be affected by the surface charge-induced electrical double layer (EDL). However, neither of these of attributes are well understood. In this paper, by introducing an EDL-induced electrostatic wetting tension, a theoretical model is first established to study the effect of EDLs formed near the solid-liquid interface and the liquid-nanobubble interface on the gas phase CA of nanobubbles. The size-dependence of this EDL interaction is studied as well. Next, by using atomic force microscopy (AFM), the effect of the EDL on nanobubbles' gas phase CA is studied with variable electrical potential at the solid-liquid interface, which is adjusted by an applied voltage. Both the theoretical and the experimental results show that the EDLs formed near the solid-liquid interface and the liquid-nanobubble interface lead to a reduction of gas phase CA of the surface nanobubbles because of an electrostatic wetting tension on the nanobubble due to the attractive electrostatic interaction between the liquid and nanobubble within the EDL, which is in the nanobubbles' outward direction. An EDL with a larger zeta potential magnitude leads to a larger gas phase CA reduction. Furthermore, the effect of EDL on the nanobubbles' gas phase CA shows a significant size-dependence considering the size dependence of the electrostatic wetting tension. The gas phase CA reduction due to the EDL decreases with increasing nanobubble height and increases with the nanobubble's increasing curvature radius, indicating that a surface charge-induced EDL could possibly explain the size dependence of the gas phase CA of nanobubbles.

A batch assay to measure microbial hydrogen sulfide production from sulfur-containing solid wastes.

PubMed

Sun, Mei; Sun, Wenjie; Barlaz, Morton A

2016-05-01

Large volumes of sulfur-containing wastes enter municipal solid waste landfills each year. Under the anaerobic conditions that prevail in landfills, oxidized forms of sulfur, primarily sulfate, are converted to sulfide. Hydrogen sulfide (H2S) is corrosive to landfill gas collection and treatment systems, and its presence in landfill gas often necessitates the installation of expensive removal systems. For landfill operators to understand the cost of managing sulfur-containing wastes, an estimate of the H2S production potential is needed. The objective of this study was to develop and demonstrate a biochemical sulfide potential (BSP) test to measure the amount of H2S produced by different types of sulfur-containing wastes in a relatively fast (30days) and inexpensive (125mL serum bottles) batch assay. This study confirmed the toxic effect of H2S on both sulfate reduction and methane production in batch systems, and demonstrated that removing accumulated H2S by base adsorption was effective for mitigating inhibition. H2S production potentials of coal combustion fly ash, flue gas desulfurization residual, municipal solid waste combustion ash, and construction and demolition waste were determined in BSP assays. After 30days of incubation, most of the sulfate in the wastes was converted to gaseous or aqueous phase sulfide, with BSPs ranging from 0.8 to 58.8mLH2S/g waste, depending on the chemical composition of the samples. Selected samples contained solid phase sulfide which contributed to the measured H2S yield. A 60day incubation in selected samples resulted in 39-86% additional sulfide production. H2S production measured in BSP assays was compared with that measured in simulated landfill reactors and that calculated from chemical analyses. H2S production in BSP assays and in reactors was lower than the stoichiometric values calculated from chemical composition for all wastes tested, demonstrating the importance of assays to estimate the microbial sulfide production potential of sulfur-containing wastes. Copyright © 2016 Elsevier B.V. All rights reserved.

Solid-phase single molecule biosensing using dual-color colocalization of fluorescent quantum dot nanoprobes

NASA Astrophysics Data System (ADS)

Liu, Jianbo; Yang, Xiaohai; Wang, Kemin; Wang, Qing; Liu, Wei; Wang, Dong

2013-10-01

The development of solid-phase surface-based single molecule imaging technology has attracted significant interest during the past decades. Here we demonstrate a sandwich hybridization method for highly sensitive detection of a single thrombin protein at a solid-phase surface based on the use of dual-color colocalization of fluorescent quantum dot (QD) nanoprobes. Green QD560-modified thrombin binding aptamer I (QD560-TBA I) were deposited on a positive poly(l-lysine) assembled layer, followed by bovine serum albumin blocking. It allowed the thrombin protein to mediate the binding of the easily detectable red QD650-modified thrombin binding aptamer II (QD650-TBA II) to the QD560-TBA I substrate. Thus, the presence of the target thrombin can be determined based on fluorescent colocalization measurements of the nanoassemblies, without target amplification or probe separation. The detection limit of this assay reached 0.8 pM. This fluorescent colocalization assay has enabled single molecule recognition in a separation-free detection format, and can serve as a sensitive biosensing platform that greatly suppresses the nonspecific adsorption false-positive signal. This method can be extended to other areas such as multiplexed immunoassay, single cell analysis, and real time biomolecule interaction studies.The development of solid-phase surface-based single molecule imaging technology has attracted significant interest during the past decades. Here we demonstrate a sandwich hybridization method for highly sensitive detection of a single thrombin protein at a solid-phase surface based on the use of dual-color colocalization of fluorescent quantum dot (QD) nanoprobes. Green QD560-modified thrombin binding aptamer I (QD560-TBA I) were deposited on a positive poly(l-lysine) assembled layer, followed by bovine serum albumin blocking. It allowed the thrombin protein to mediate the binding of the easily detectable red QD650-modified thrombin binding aptamer II (QD650-TBA II) to the QD560-TBA I substrate. Thus, the presence of the target thrombin can be determined based on fluorescent colocalization measurements of the nanoassemblies, without target amplification or probe separation. The detection limit of this assay reached 0.8 pM. This fluorescent colocalization assay has enabled single molecule recognition in a separation-free detection format, and can serve as a sensitive biosensing platform that greatly suppresses the nonspecific adsorption false-positive signal. This method can be extended to other areas such as multiplexed immunoassay, single cell analysis, and real time biomolecule interaction studies. Electronic supplementary information (ESI) available: Absorbance and fluorescence spectra of quantum dot nanoprobes, electrophoresis analysis, and experimental setup for fluorescence imaging with dual channels. See DOI: 10.1039/c3nr03291d

Development Of Antibody-Based Fiber-Optic Sensors

NASA Astrophysics Data System (ADS)

Tromberg, Bruce J.; Sepaniak, Michael J.; Vo-Dinh, Tuan

1988-06-01

The speed and specificity characteristic of immunochemical complex formation has encouraged the development of numerous antibody-based analytical techniques. The scope and versatility of these established methods can be enhanced by combining the principles of conventional immunoassay with laser-based fiber-optic fluorimetry. This merger of spectroscopy and immunochemistry provides the framework for the construction of highly sensitive and selective fiber-optic devices (fluoroimmuno-sensors) capable of in-situ detection of drugs, toxins, and naturally occurring biochemicals. Fluoroimmuno-sensors (FIS) employ an immobilized reagent phase at the sampling terminus of a single quartz optical fiber. Laser excitation of antibody-bound analyte produces a fluorescence signal which is either directly proportional (as in the case of natural fluorophor and "antibody sandwich" assays) or inversely proportional (as in the case of competitive-binding assays) to analyte concentration. Factors which influence analysis time, precision, linearity, and detection limits include the nature (solid or liquid) and amount of the reagent phase, the method of analyte delivery (passive diffusion, convection, etc.), and whether equilibrium or non-equilibrium assays are performed. Data will be presented for optical fibers whose sensing termini utilize: (1) covalently-bound solid antibody reagent phases, and (2) membrane-entrapped liquid antibody reagents. Assays for large-molecular weight proteins (antigens) and small-molecular weight, carcinogenic, polynuclear aromatics (haptens) will be considered. In this manner, the influence of a system's chemical characteristics and measurement requirements on sensor design, and the consequence of various sensor designs on analytical performance will be illustrated.

Synthesis and binding studies of Alzheimer ligands on solid support.

PubMed

Rzepecki, Petra; Geib, Nina; Peifer, Manuel; Biesemeier, Frank; Schrader, Thomas

2007-05-11

Aminopyrazole derivatives constitute the first class of nonpeptidic rationally designed beta-sheet ligands. Here we describe a double solid-phase protocol for both synthesis and affinity testing. The presented solid-phase synthesis of four types of hybrid compounds relies on the Fmoc strategy and circumvents subsequent HPLC purification by precipitating the final product from organic solution in pure form. Hexa- and octapeptide pendants with internal di- and tetrapeptide bridges are now amenable in high yields to combinatorial synthesis of compound libraries for high-throughput screening purposes. Solid-phase peptide synthesis (SPPS) on an acid-resistant PAM allows us, after PMB deprotection, to subject the free aminopyrazole binding sites in an immobilized state to on-bead assays with fluorescence-labeled peptides. From the fluorescence emission intensity decrease, individual binding constants can be calculated via reference curves by simple application of the law of mass action. Gratifyingly, host/guest complexation can be monitored quantitatively even for those ligands, which are almost insoluble in water.

Evaporation of pure liquid sessile and spherical suspended drops: a review.

PubMed

Erbil, H Yildirim

2012-01-15

A sessile drop is an isolated drop which has been deposited on a solid substrate where the wetted area is limited by a contact line and characterized by contact angle, contact radius and drop height. Diffusion-controlled evaporation of a sessile drop in an ambient gas is an important topic of interest because it plays a crucial role in many scientific applications such as controlling the deposition of particles on solid surfaces, in ink-jet printing, spraying of pesticides, micro/nano material fabrication, thin film coatings, biochemical assays, drop wise cooling, deposition of DNA/RNA micro-arrays, and manufacture of novel optical and electronic materials in the last decades. This paper presents a review of the published articles for a period of approximately 120 years related to the evaporation of both sessile drops and nearly spherical droplets suspended from thin fibers. After presenting a brief history of the subject, we discuss the basic theory comprising evaporation of micrometer and millimeter sized spherical drops, self cooling on the drop surface and evaporation rate of sessile drops on solids. The effects of drop cooling, resultant lateral evaporative flux and Marangoni flows on evaporation rate are also discussed. This review also has some special topics such as drop evaporation on superhydrophobic surfaces, determination of the receding contact angle from drop evaporation, substrate thermal conductivity effect on drop evaporation and the rate evaporation of water in liquid marbles. Copyright © 2011 Elsevier B.V. All rights reserved.

Performance of an automated solid-phase red cell adherence system compared with that of a manual gel microcolumn assay for the identification of antibodies eluted from red blood cells.

PubMed

Finck, R H; Davis, R J; Teng, S; Goldfinger, D; Ziman, A F; Lu, Q; Yuan, S

2011-01-01

IgG antibodies coating red blood cells (RBCs) can be removed by elution procedures and their specificity determined by antibody identification studies. Although such testing is traditionally performed using the tube agglutination assay, prior studies have shown that the gel microcolumn (GMC) assay may also be used with comparable results. The purpose of this study was to compare an automated solid-phase red cell adherence (SPRCA) system with a GMC assay for the detection of antibodies eluted from RBCs. Acid eluates from 51 peripheral blood (PB) and 7 cord blood (CB) samples were evaluated by both an automated SPRCA instrument and a manual GMC assay. The concordance rate between the two systems for peripheral RBC samples was 88.2 percent (45 of 51), including cases with alloantibodies (n = 8), warm autoantibodies (n = 12), antibodies with no identifiable specificity (n = 2), and negative results (n = 23). There were six discordant cases, of which four had alloantibodies (including anti-Jka, -E, and -e) demonstrable by the SPRCA system only. In the remaining 2 cases, anti-Fya and antibodies with no identifiable specificity were demonstrable by the GMC assay only. All seven CB specimens produced concordant results, showing anti-A (n = 3), -B (n = 1), maternal anti-Jka (n = 2), or a negative result (n = 1). Automated SPRCA technology has a performance that is comparable with that of a manual GMC assay for identifying antibodies eluted from PB and CB RBCs.

Evaporation of liquid droplets on solid substrates. II. Periodic substrates with moving contact lines

NASA Astrophysics Data System (ADS)

Amini, Amirhossein; Homsy, G. M.

2017-04-01

Experiments on evaporating droplets on structured surfaces have shown that the contact line does not move with constant speed, but rather in a steplike "stick-slip" fashion. As a first step in understanding such behavior, we study the evaporation of a two-dimensional volatile liquid droplet on a nonplanar heated solid substrate with a moving contact line and fixed contact angle. The model for the flat case is adapted to include curved substrates, numerical solutions are achieved for various periodic and quasiperiodic substrate profiles, and the dynamics of the contact line and the apparent contact angle are studied. In contrast with our results for a flat substrate, for which the contact line recedes in a nearly constant speed, we observe that the contact line speed and position show significant time variation and that the contact line moves in an approximate steplike fashion on relatively steep substrates. For the simplest case of a periodic substrate, we find that the apparent contact angle is periodic in time. For doubly periodic substrates, we find that the apparent contact angle is periodic and that the problem exhibits a phase-locking behavior. For multimode quasiperiodic substrates, we find the contact line behavior to be temporally complex and not only limited to a stick-slip motion. In all cases, we find that the overall evaporation is increased relative to the flat substrate.

Dancing drops over vibrating substrates

NASA Astrophysics Data System (ADS)

Borcia, Rodica; Borcia, Ion Dan; Helbig, Markus; Meier, Martin; Egbers, Christoph; Bestehorn, Michael

2017-04-01

We study the motion of a liquid drop on a solid plate simultaneously submitted to horizontal and vertical harmonic vibrations. The investigation is done via a phase field model earlier developed for describing static and dynamic contact angles. The density field is nearly constant in every bulk region (ρ = 1 in the liquid phase, ρ ≈ 0 in the vapor phase) and varies continuously from one phase to the other with a rapid but smooth variation across the interfaces. Complicated explicit boundary conditions along the interface are avoided and captured implicitly by gradient terms of ρ in the hydrodynamic basic equations. The contact angle θ is controlled through the density at the solid substrate ρ S , a free parameter varying between 0 and 1 [R. Borcia, I.D. Borcia, M. Bestehorn, Phys. Rev. E 78, 066307 (2008)]. We emphasize the swaying and the spreading modes, earlier theoretically identified by Benilov and Billingham via a shallow-water model for drops climbing uphill along an inclined plane oscillating vertically [E.S. Benilov, J. Billingham, J. Fluid Mech. 674, 93 (2011)]. The numerical phase field simulations will be completed by experiments. Some ways to prevent the release of the dancing drops along a hydrophobic surface into the gas atmosphere are also discussed in this paper.

Clinical cytometry and progress in HLA antibody detection.

PubMed

Bray, Robert A; Tarsitani, Christine; Gebel, Howard M; Lee, Jar-How

2011-01-01

For most solid organ and selected stem cell transplants, antibodies against mismatched HLA antigens can lead to early and late graft failure. In recognition of the clinical significance of these antibodies, HLA antibody identification is one of the most critical functions of histocompatibility laboratories. Early methods employed cumbersome and insensitive complement-dependent cytotoxicity assays with a visual read-out. A little over 20 years ago flow cytometry entered the realm of antibody detection with the introduction of the flow cytometric crossmatch. Cytometry's increased sensitivity and objectivity quickly earned it popularity as a preferred crossmatch method especially for sensitized recipients. Although a sensitive method, the flow crossmatch was criticized as being "too sensitive" as false positive reactions were a know drawback. In part, the shortcomings of the flow crossmatch were due to the lack of corresponding sensitive and specific HLA antibody screening assays. However, in the mid 1990s, solid phase assays, capable of utilizing standard flow cytometers, were developed. These assays used microparticles coated with purified HLA molecules. Hence, the era of solid-phase, microparticle technology for HLA antibody detection was born permitting the sensitive and specific detection of HLA antibody. It was now possible to provide better correlation between HLA antibody detection and the flow cytometric crossmatch. This flow-based technology was soon followed by adaptation to the Luminex platform permitting a mutltiplexed approach for the identification and characterization of HLA antibodies. It is hoped that these technologies will ultimately lead to the identification of parameters that best correlate with and/or predict transplant outcomes. Copyright © 2011 Elsevier Inc. All rights reserved.

Characterization of Estrogen and Androgen Activity of Food Contact Materials by Different In Vitro Bioassays (YES, YAS, ERα and AR CALUX) and Chromatographic Analysis (GC-MS, HPLC-MS)

PubMed Central

Osorio, Veronica; Grininger, Angelika; Richter, Alexander; Bergmair, Johannes; Pyerin, Michael; Washüttl, Michael; Tacker, Manfred

2014-01-01

Endocrine active substances (EAS) show structural similarities to natural hormones and are suspected to affect the human endocrine system by inducing hormone dependent effects. Recent studies with in vitro tests suggest that EAS can leach from packaging into food and may therefore pose a risk to human health. Sample migrates from food contact materials were tested for estrogen and androgen agonists and antagonists with different commonly used in vitro tests. Additionally, chemical trace analysis by GC-MS and HPLC-MS was used to identify potential hormone active substances in sample migrates. A GC-MS method to screen migrates for 29 known or potential endocrine active substances was established and validated. Samples were migrated according to EC 10/2011, concentrated by solid phase extraction and tested with estrogen and androgen responsive reporter gene assays based on yeast cells (YES and YAS) or human osteoblast cells (ERα and AR CALUX). A high level of agreement between the different bioassays could be observed by screening for estrogen agonists. Four out of 18 samples tested showed an estrogen activity in a similar range in both, YES and ERα CALUX. Two more samples tested positive in ERα CALUX due to the lower limits of detection in this assay. Androgen agonists could not be detected in any of the tested samples, neither with YAS nor with AR CALUX. When testing for antagonists, significant differences between yeast and human cell-based bioassays were noticed. Using YES and YAS many samples showed a strong antagonistic activity which was not observed using human cell-based CALUX assays. By GC-MS, some known or supposed EAS were identified in sample migrates that showed a biological activity in the in vitro tests. However, no firm conclusions about the sources of the observed hormone activity could be obtained from the chemical results. PMID:25000404

Dynamics of water droplets detached from porous surfaces of relevance to PEM fuel cells.

PubMed

Theodorakakos, A; Ous, T; Gavaises, M; Nouri, J M; Nikolopoulos, N; Yanagihara, H

2006-08-15

The detachment of liquid droplets from porous material surfaces used with proton exchange membrane (PEM) fuel cells under the influence of a cross-flowing air is investigated computationally and experimentally. CCD images taken on a purpose-built transparent fuel cell have revealed that the water produced within the PEM is forming droplets on the surface of the gas-diffusion layer. These droplets are swept away if the velocity of the flowing air is above a critical value for a given droplet size. Static and dynamic contact angle measurements for three different carbon gas-diffusion layer materials obtained inside a transparent air-channel test model have been used as input to the numerical model; the latter is based on a Navier-Stokes equations flow solver incorporating the volume of fluid (VOF) two-phase flow methodology. Variable contact angle values around the gas-liquid-solid contact-line as well as their dynamic change during the droplet shape deformation process, have allowed estimation of the adhesion force between the liquid droplet and the solid surface and successful prediction of the separation line at which droplets loose their contact from the solid surface under the influence of the air stream flowing around them. Parametric studies highlight the relevant importance of various factors affecting the detachment of the liquid droplets from the solid surface.

Circulating Immune Complexes in Lyme Arthritis

PubMed Central

Hardin, John A.; Walker, Lesley C.; Steere, Allen C.; Trumble, Thomas C.; Tung, Kenneth S. K.; Williams, Ralph C.; Ruddy, Shaun; Malawista, Stephen E.

1979-01-01

We have found immunoglobulin (Ig) G-containing material consistent with immune complexes in the sera of patients with Lyme arthritis. It was detected in 29 of 55 sera (55%) from 31 patients by at least one of three assays: 125I-C1q binding, C1q solid phase, or Raji cell. The presence of reactive material correlated with clinical aspects of disease activity; it was found early in the illness, was most prominent in sera from the sickest patients, was infrequent during remissions, and often fluctuated in parallel with changes in clinical status. The results in the two C1q assays showed a strong positive correlation (P<0.001). They were each elevated in 45% of the sera and were usually concordant (85%). In contrast, the Raji cell assay was less frequently positive and often discordant with the C1q assays. In sucrose density gradients, putative circulating immune complexes sedimented near 19S; they, too, were detected best by the two assays based on C1q binding. An additional 7S component was found in some sera by the 125I-C1q binding assay. Serum complement was often above the range of normal in patients with mild disease and normal in patients with severe disease but did not correlate significantly with levels of circulating immune complexes. IgM and IgG rheumatoid factors were not detectable. These findings support a role for immune complexes in the pathogenesis of Lyme arthritis. Their measurement, by either the 125I-C1q binding assay or by the C1q solid phase assay, often provides a sensitive index of disease activity. Moreover, the complexes are likely sources of disease-related antigens for further study of this new disorder. PMID:429566

Dependence of charge transfer phenomena during solid-air two-phase flow on particle disperser

NASA Astrophysics Data System (ADS)

Tanoue, Ken-ichiro; Suedomi, Yuuki; Honda, Hirotaka; Furutani, Satoshi; Nishimura, Tatsuo; Masuda, Hiroaki

2012-12-01

An experimental investigation of the tribo-electrification of particles has been conducted during solid-air two-phase turbulent flow. The current induced in a metal plate by the impact of polymethylmethacrylate (PMMA) particles in a high-speed air flow was measured for two different plate materials. The results indicated that the contact potential difference between the particles and a stainless steel plate was positive, while for a nickel plate it was negative. These results agreed with theoretical contact charge transfer even if not only the particle size but also the kind of metal plate was changed. The specific charge of the PMMA particles during solid-air two-phase flow using an ejector, a stainless steel branch pipe, and a stainless steel straight pipe was measured using a Faraday cage. Although the charge was negative in the ejector, the particles had a positive specific charge at the outlet of the branch pipe, and this positive charge increased in the straight pipe. The charge decay along the flow direction could be reproduced by the charging and relaxation theory. However, the proportional coefficients in the theory changed with the particle size and air velocity. Therefore, an unexpected charge transfer occurred between the ejector and the branch pipe, which could not be explained solely by the contact potential difference. In the ejector, an electrical current in air might have been produced by self-discharge of particles with excess charge between the nickel diffuser in the ejector and the stainless steel nozzle or the stainless steel pipe due to a reversal in the contact potential difference between the PMMA and the stainless steel. The sign of the current depended on the particle size, possibly because the position where the particles impacted depended on their size. When dual coaxial glass pipes were used as a particle disperser, the specific charge of the PMMA particles became more positive along the particle flow direction due to the contact potential difference between the PMMA and the stainless steel. Furthermore, the current in air using the dual coaxial glass pipes was less than that using the ejector.

Lubricant-impregnated surfaces for electrochemical applications, and devices and systems using same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Solomon, Brian Richmond; Chen, Xinwei; Chiang, Yet-Ming

In certain embodiments, the invention relates to an electrochemical device having a liquid lubricant impregnated surface. At least a portion of the interior surface of the electrochemical device includes a portion that includes a plurality of solid features disposed therein. The plurality of solid features define a plurality of regions therebetween. A lubricant is disposed in the plurality of regions which retain the liquid lubricant in the plurality of regions during operation of the device. An electroactive phase comes in contact with at least the portion of the interior surface. The liquid lubricant impregnated surface introduces a slip at themore » surface when the electroactive phase flows along the surface. The electroactive phase may be a yield stress fluid.« less

Dependency of the apparent contact angle on nonisothermal conditions

NASA Astrophysics Data System (ADS)

Krahl, Rolf; Gerstmann, Jens; Behruzi, Philipp; Bänsch, Eberhard; Dreyer, Michael E.

2008-04-01

The dynamic behavior of liquids in partly filled containers is influenced to a large extend by the angle between the gas-liquid phase boundary and the solid container wall at the contact line. This contact angle in turn is influenced by nonisothermal conditions. In the case of a cold liquid meniscus spreading over a hot solid wall, the contact angle apparently becomes significantly larger. In this paper we want to establish a quantitative equation for this enlargement, both from experimental and numerical data. Our findings can be used to build a subgrid model for computations, where the resolution is not sufficient to resolve the boundary layers. This might be the case for large containers which are exposed to low accelerations and where the contact angle boundary condition determines the position of the free surface. These types of computation are performed, for example, to solve propellant management problems in launcher and satellite tanks. In this application, the knowledge of the position of the free surface is very important for the withdrawal of liquid and the calculation of heat and mass transfer.

REMOVAL OF CERTAIN FISSION PRODUCT METALS FROM LIQUID BISMUTH COMPOSITIONS

DOEpatents

Dwyer, O.E.; Howe, H.E.; Avrutik, E.R.

1959-11-24

A method is described for purifying a solution of urarium in liquid bismuth containing at least one metal from the group consisting of selenium, tellurium, palladium, ruthenium, rhodium, niobium, and zirconium. The solution is contacted with zinc in an inert atmosphere to form a homogeneous melt, a solid zinc phase is formed, and the zinc phase containing the metal is separated from the melt.

Simultaneous determination of celecoxib, hydroxycelecoxib, and carboxycelecoxib in human plasma using gradient reversed-phase liquid chromatography with ultraviolet absorbance detection.

PubMed

Störmer, Elke; Bauer, Steffen; Kirchheiner, Julia; Brockmöller, Jürgen; Roots, Ivar

2003-01-05

A new HPLC method for the simultaneous determination of celecoxib, carboxycelecoxib and hydroxycelecoxib in human plasma samples has been developed. Following a solid-phase extraction procedure, the samples were separated by gradient reversed-phase HLPC (C(18)) and quantified using UV detection at 254 nm. The method was linear over the concentration range 10-500 ng/ml. The intra-assay variability for the three analytes ranged from 4.0 to 12.6% and the inter-assay variability from 4.9 to 14.2%. The achieved limits of quantitation (LOQ) of 10 ng/ml for each analyte allowed the determination of the pharmacokinetic parameters of the analytes after administration of 100 mg celecoxib.

Method for stabilizing low-level mixed wastes at room temperature

DOEpatents

Wagh, A.S.; Singh, D.

1997-07-08

A method to stabilize solid and liquid waste at room temperature is provided comprising combining solid waste with a starter oxide to obtain a powder, contacting the powder with an acid solution to create a slurry, said acid solution containing the liquid waste, shaping the now-mixed slurry into a predetermined form, and allowing the now-formed slurry to set. The invention also provides for a method to encapsulate and stabilize waste containing cesium comprising combining the waste with Zr(OH){sub 4} to create a solid-phase mixture, mixing phosphoric acid with the solid-phase mixture to create a slurry, subjecting the slurry to pressure; and allowing the now pressurized slurry to set. Lastly, the invention provides for a method to stabilize liquid waste, comprising supplying a powder containing magnesium, sodium and phosphate in predetermined proportions, mixing said powder with the liquid waste, such as tritium, and allowing the resulting slurry to set. 4 figs.

Method for stabilizing low-level mixed wastes at room temperature

DOEpatents

Wagh, Arun S.; Singh, Dileep

1997-01-01

A method to stabilize solid and liquid waste at room temperature is provided comprising combining solid waste with a starter oxide to obtain a powder, contacting the powder with an acid solution to create a slurry, said acid solution containing the liquid waste, shaping the now-mixed slurry into a predetermined form, and allowing the now-formed slurry to set. The invention also provides for a method to encapsulate and stabilize waste containing cesium comprising combining the waste with Zr(OH).sub.4 to create a solid-phase mixture, mixing phosphoric acid with the solid-phase mixture to create a slurry, subjecting the slurry to pressure; and allowing the now pressurized slurry to set. Lastly, the invention provides for a method to stabilize liquid waste, comprising supplying a powder containing magnesium, sodium and phosphate in predetermined proportions, mixing said powder with the liquid waste, such as tritium, and allowing the resulting slurry to set.

Analytical solutions for combined close-contact and natural convection melting in horizontal cylindrical heat storage capsule

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saitoh, T.S.; Hoshi, A.

1998-07-01

Melting and solidification of a phase change material (PCM) in a capsule is of practical importance in latent heat thermal energy storage (LHTES) systems which are considered to be very promising to reduce a peak demand of electricity in the summer season and carbon dioxide (CO{sub 2}) emissions. Two melting modes are involved in melting of capsules. One is close-contact melting between the solid bulk and the capsule wall, and another is natural convection melting in the liquid region. Close-contact melting processes for a single enclosure have been solved using several numerical methods (e.g., Saitoh and Kato (1994)). In additionmore » close-contact melting heat transfer characteristics including melt flow in the liquid film under inner wall temperature distribution were analyzed and simple approximate equations were already presented by Saitoh and Hoshi (1997). The effects of Stefan number and variable temperature profile etc. were clarified in detail. And the melting velocity of the solid bulk under various conditions was also studied theoretically. In addition the effects of variable inner wall temperature on molten mass fraction were investigated. The present paper reports analytical solutions for combined close-contact and natural convection melting in horizontal cylindrical capsule. Moreover, natural convection melting in the liquid region were analyzed in this report. The upper interface shape of the solid bulk is approximated by a circular arc throughout the melting process. For the sake of verification, close-contact melting heat-transfer characteristics including natural convection in the liquid region were studied experimentally. Apparent shift of upper solid-liquid interface is good agreement with the experiment. The present simple approximate solutions will be useful to facilitate designing of the practical capsule bed LHTES systems.« less

Ion adsorption-induced wetting transition in oil-water-mineral systems.

PubMed

Mugele, Frieder; Bera, Bijoyendra; Cavalli, Andrea; Siretanu, Igor; Maestro, Armando; Duits, Michel; Cohen-Stuart, Martien; van den Ende, Dirk; Stocker, Isabella; Collins, Ian

2015-05-27

The relative wettability of oil and water on solid surfaces is generally governed by a complex competition of molecular interaction forces acting in such three-phase systems. Herein, we experimentally demonstrate how the adsorption of in nature abundant divalent Ca(2+) cations to solid-liquid interfaces induces a macroscopic wetting transition from finite contact angles (≈ 10°) with to near-zero contact angles without divalent cations. We developed a quantitative model based on DLVO theory to demonstrate that this transition, which is observed on model clay surfaces, mica, but not on silica surfaces nor for monovalent K(+) and Na(+) cations is driven by charge reversal of the solid-liquid interface. Small amounts of a polar hydrocarbon, stearic acid, added to the ambient decane synergistically enhance the effect and lead to water contact angles up to 70° in the presence of Ca(2+). Our results imply that it is the removal of divalent cations that makes reservoir rocks more hydrophilic, suggesting a generalizable strategy to control wettability and an explanation for the success of so-called low salinity water flooding, a recent enhanced oil recovery technology.

High Speed Solid State Circuit Breaker

NASA Technical Reports Server (NTRS)

Podlesak, Thomas F.

1993-01-01

The U.S. Army Research Laboratory, Fort Monmouth, NJ, has developed and is installing two 3.3 MW high speed solid state circuit breakers at the Army's Pulse Power Center. These circuit breakers will interrupt 4160V three phase power mains in no more than 300 microseconds, two orders of magnitude faster than conventional mechanical contact type circuit breakers. These circuit breakers utilize Gate Turnoff Thyristors (GTO's) and are currently utility type devices using air cooling in an air conditioned enclosure. Future refinements include liquid cooling, either water or two phase organic coolant, and more advanced semiconductors. Each of these refinements promises a more compact, more reliable unit.

Detection of influenza A virus subtypes using a solid-phase PCR microplate chip assay.

PubMed

Sun, Xin-Cheng; Wang, YunLong; Yang, Liping; Zhang, HuiRu

2015-01-01

A rapid and sensitive microplate chip based on solid PCR was developed to identify influenza A subtypes. A simple ultraviolet cross-linking method was used to immobilize DNA probes on pretreated microplates. Solid-phase PCR was proven to be a convenient method for influenza A screening. The sensitivity of the microplate chip was 10(-3) μg/mL for the enzymatic colorimetric method and 10(-4) μg/mL for the fluorescence method. The 10 sets of primers and probes for the microplate chip were highly specific and did not interfere with each other. These results suggest that the microplate chip based on solid PCR can be used to rapidly detect universal influenza A and its subtypes. This platform can also be used to detect other pathogenic microorganisms. Copyright © 2014 Elsevier B.V. All rights reserved.

Evaluation of flow hydrodynamics in a pilot-scale dissolved air flotation tank: a comparison between CFD and experimental measurements.

PubMed

Lakghomi, B; Lawryshyn, Y; Hofmann, R

2015-01-01

Computational fluid dynamics (CFD) models of dissolved air flotation (DAF) have shown formation of stratified flow (back and forth horizontal flow layers at the top of the separation zone) and its impact on improved DAF efficiency. However, there has been a lack of experimental validation of CFD predictions, especially in the presence of solid particles. In this work, for the first time, both two-phase (air-water) and three-phase (air-water-solid particles) CFD models were evaluated at pilot scale using measurements of residence time distribution, bubble layer position and bubble-particle contact efficiency. The pilot-scale results confirmed the accuracy of the CFD model for both two-phase and three-phase flows, but showed that the accuracy of the three-phase CFD model would partly depend on the estimation of bubble-particle attachment efficiency.

Method of producing a colloidal fuel from coal and a heavy petroleum fraction

DOEpatents

Longanbach, James R.

1983-08-09

A method is provided for combining coal as a colloidal suspension within a heavy petroleum fraction. The coal is broken to a medium particle size and is formed into a slurry with a heavy petroleum fraction such as a decanted oil having a boiling point of about 300.degree.-550.degree. C. The slurry is heated to a temperature of 400.degree.-500.degree. C. for a limited time of only about 1-5 minutes before cooling to a temperature of less than 300.degree. C. During this limited contact time at elevated temperature the slurry can be contacted with hydrogen gas to promote conversion. The liquid phase containing dispersed coal solids is filtered from the residual solids and recovered for use as a fuel or feed stock for other processes. The residual solids containing some carbonaceous material are further processed to provide hydrogen gas and heat for use as required in this process.

Modified resins for solid-phase extraction

DOEpatents

Fritz, James S.; Sun, Jeffrey J.

1993-07-27

A process of treating aqueous solutions to remove organic solute contaminants by contacting an aqueous solution containing polar organic solute contaminants with a functionalized polystyrene-divinyl benzene adsorbent resin, with the functionalization of said resin being accomplished by organic hydrophilic groups such as hydroxymethyl, acetyl and cyanomethyl.

Modified resins for solid-phase extraction

DOEpatents

Fritz, James S.; Sun, Jeffrey J.

1991-12-10

A process of treating aqueous solutions to remove organic solute contaminants by contacting an aqueous solution containing polar organic solute contaminants with a functionalized polystyrene-divinyl benzene adsorbent resin, with the functionalization of said resin being accomplished by organic hydrophilic groups such as hydroxymethyl, acetyl and cyanomethyl.

Structural ordering at solid-liquid interfaces in Al-Sm system: A molecular-dynamics study

DOE PAGES

Sun, Yang; Zhang, Feng; Ye, Zhuo; ...

2016-07-12

The structural ordering at solid-liquid interfaces far from equilibrium is studied with molecular dynamics simulations for the Al-Sm system. Using the van-Hove self-correlation function as the criterion to identify attachment/detachment events that occur at the interface, we are able to determine the time-dependent interface position, and characterize the detailed interfacial structure ordering surrounding the attached atoms. For the interface between an undercooled Al90Sm10 liquid and a metastable cubic structure, the solid induces the crystalline order of the cubic phase in the liquid layers, promoting the continuous growth of the crystal phase. When the same liquid is put in contact withmore » f.c.c. Al, Sm from the liquid can still attach to the solid interface despite its insolubility in the Al lattice. Non-f.c.c. order is revealed surrounding the attached Sm atoms. Lastly, we show that the local structure ordering at interface is highly correlated to solid packing and liquid ordering.« less

Metastable nanobubbles at the solid-liquid interface due to contact angle hysteresis.

PubMed

Nishiyama, Takashi; Yamada, Yutaka; Ikuta, Tatsuya; Takahashi, Koji; Takata, Yasuyuki

2015-01-27

Nanobubbles exist at solid-liquid interfaces between pure water and hydrophobic surfaces with very high stability, lasting in certain cases up to several days. Not only semispherical but also other shapes, such as micropancakes, are known to exist at such interfaces. However, doubt has been raised as to whether or not the nanobubbles are gas-phase entities. In this study, surface nanobubbles at a pure water-highly ordered pyrolytic graphite (HOPG) interface were investigated by peak force quantitative nanomechanics (PF-QNM). Multiple isolated nanobubbles generated by the solvent-exchange method were present on the terraced areas, avoiding the steps of the HOPG surface. Adjacent nanobubbles coalesced and formed metastable nanobubbles. Coalescence was enhanced by the PF-QNM measurement. We determined that nanobubbles can exist for a long time because of nanoscale contact angle hysteresis at the water-HOPG interface. Moreover, the hydrophilic steps of HOPG were avoided during coalescence, providing evidence that the nanobubbles are truly gas phase.

Matrix solid-phase dispersion extraction of organophosphorus pesticide using SiO2-poly(N-vinylimidazole)

NASA Astrophysics Data System (ADS)

Gutiérrez-Solís, M. C.; Muñoz-Rodríguez, D.; Medina-Peralta, S.; Carrera-Figueiras, C.; Ávila-Ortega, A.

2013-06-01

A sorbent material based on silica particles modified with poly(N-vinylimidazole) (SiO2-PVI) has been evaluated for the treatment of samples by matrix solid-phase dispersion (MSPD). The extraction of four organophosphorus pesticides was done from a spiked tomato and the extracts were analyzed by gas chromatography coupled to mass spectrometry. Six elution solvents were evaluated and acetone was selected due to better recovery of the four pesticides and low background signal in the chromatograms. A factorial design 24 was used for selection of extraction conditions. The factors were contact time, acetone volume, treatment (with or without freeze-drying) and adsorbent (SiO2 or SiO2-PVI). The best recoveries were obtained using 15 minutes of contact, 2 mL of solvent and sorbent without freeze-drying. The recoveries were between 60 and 83% for SiO2-PVI in spiked tomato with 0.2 and 0.8μg/g.

Immunoassay for wheat processing quality: utilization of a sandwich assay incorporating an immobilized single-chain fragment.

PubMed

Hill, A S; Giersch, T M; Loh, C S; Skerritt, J H

1999-10-01

A single-chain fragment (scFv) was engineered from a monoclonal antibody to high molecular weight glutenin subunits (HMW-GS), wheat flour polypeptides that play a major role in determining the mixing- and extension strength-related properties of dough and its subsequent baking performance. The scFv was expressed in a thioredoxin mutant Escherichia coli strain that allows disulfide bond formation in the cytoplasm and incorporated into a diagnostic test for wheat quality. Although the scFv lacks the more highly conserved antibody constant regions usually involved with immobilization, it was able to be directly immobilized to a polystyrene microwell solid phase without chemical or covalent modification of the protein or solid phase and utilized as a capture antibody in a double-antibody (two-site) immunoassay. In the sandwich assay, increasing HMW-GS concentrations produced increasing assay color, and highly significant correlations were obtained between optical densities obtained in the ELISA using the scFv and the content of large glutenin polymers in flours as well as measures of dough strength as measured by resistance to dough extension in rheological testing. The assay using the scFv was able to be carried out at lower flour sample extract dilutions than that required for a similar assay utilizing a monoclonal capture antibody. This research shows that engineered antibody fragments can be utilized to provide superior assay performance in two-site ELISAs over monoclonal antibodies and is the first application of an engineered antibody to the analysis of food processing quality.

On-chip multiplexed solid-phase nucleic acid hybridization assay using spatial profiles of immobilized quantum dots and fluorescence resonance energy transfer.

PubMed

Noor, M Omair; Tavares, Anthony J; Krull, Ulrich J

2013-07-25

A microfluidic based solid-phase assay for the multiplexed detection of nucleic acid hybridization using quantum dot (QD) mediated fluorescence resonance energy transfer (FRET) is described herein. The glass surface of hybrid glass-polydimethylsiloxane (PDMS) microfluidic channels was chemically modified to assemble the biorecognition interface. Multiplexing was demonstrated using a detection system that was comprised of two colors of immobilized semi-conductor QDs and two different oligonucleotide probe sequences. Green-emitting and red-emitting QDs were paired with Cy3 and Alexa Fluor 647 (A647) labeled oligonucleotides, respectively. The QDs served as energy donors for the transduction of dye labeled oligonucleotide targets. The in-channel assembly of the biorecognition interface and the subsequent introduction of oligonucleotide targets was accomplished within minutes using a combination of electroosmotic flow and electrophoretic force. The concurrent quantification of femtomole quantities of two target sequences was possible by measuring the spatial coverage of FRET sensitized emission along the length of the channel. In previous reports, multiplexed QD-FRET hybridization assays that employed a ratiometric method for quantification had challenges associated with lower analytical sensitivity arising from both donor and acceptor dilution that resulted in reduced energy transfer pathways as compared to single-color hybridization assays. Herein, a spatial method for quantification that is based on in-channel QD-FRET profiles provided higher analytical sensitivity in the multiplexed assay format as compared to single-color hybridization assays. The selectivity of the multiplexed hybridization assays was demonstrated by discrimination between a fully-complementary sequence and a 3 base pair sequence at a contrast ratio of 8 to 1. Copyright © 2013 Elsevier B.V. All rights reserved.

Paper-based solid-phase multiplexed nucleic acid hybridization assay with tunable dynamic range using immobilized quantum dots as donors in fluorescence resonance energy transfer.

PubMed

Noor, M Omair; Krull, Ulrich J

2013-08-06

A multiplexed solid-phase nucleic acid hybridization assay on a paper-based platform is presented using multicolor immobilized quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET). The surface of paper was modified with imidazole groups to immobilize two types of QD-probe oligonucleotide conjugates that were assembled in solution. Green-emitting QDs (gQDs) and red-emitting QDs (rQDs) served as donors with Cy3 and Alexa Fluor 647 (A647) acceptors. The gQD/Cy3 FRET pair served as an internal standard, while the rQD/A647 FRET pair served as a detection channel, combining the control and analytical test zones in one physical location. Hybridization of dye-labeled oligonucleotide targets provided the proximity for FRET sensitized emission from the acceptor dyes, which served as an analytical signal. Hybridization assays in the multicolor format provided a limit of detection of 90 fmol and an upper limit of dynamic range of 3.5 pmol. The use of an array of detection zones was designed to provide improved analytical figures of merit compared to that which could be achieved on one type of array design in terms of relative concentration of multicolor QDs. The hybridization assays showed excellent resistance to nonspecific adsorption of oligonucleotides. Selectivity of the two-plex hybridization assay was demonstrated by single nucleotide polymorphism (SNP) detection at a contrast ratio of 50:1. Additionally, it is shown that the use of preformed QD-probe oligonucleotide conjugates and consideration of the relative number density of the two types of QD-probe conjugates in the two-color assay format is advantageous to maximize assay sensitivity and the upper limit of dynamic range.

Contact line friction of electrowetting actuated viscous droplets

NASA Astrophysics Data System (ADS)

Vo, Quoc; Tran, Tuan

2018-06-01

We examine the contact line friction coefficient of viscous droplets spreading and retracting on solid surfaces immersed in ambient oil. By using the electrowetting effect, we generate a surface tension imbalance to drive the spreading and the retracting motion of the three-phase contact line (TCL). We show that neither the driving force intensity nor TCL direction significantly influences the friction coefficient. Instead, the friction coefficient depends equivalently on the viscosity of liquid droplets and the surrounding oil. We derive and experimentally verify a transient timescale that can be used to characterize both the spreading and retracting dynamics.

Catalytic method for synthesizing hydrocarbons

DOEpatents

Sapienza, R.S.; Sansone, M.J.; Slegeir, W.A.R.

A method for synthesizing hydrocarbons from carbon monoxide and hydrogen by contacting said gases with a slurry of a catalyst composed of palladium or platinum and cobalt supported on a solid phase is disclosed. The catalyst is prepared by heating a heterogeneous component of the palladium or platinum deposited on the solid support in a solution of cobalt carbonyl or precursors thereof. The catalyst exhibits excellent activity, stability in air, and produces highly desirable product fractions even with dilute gaseous reactants.

Catalytic method for synthesizing hydrocarbons

DOEpatents

Sapienza, Richard S.; Sansone, Michael J.; Slegeir, William A. R.

1984-01-01

A method for synthesizing hydrocarbons from carbon monoxide and hydrogen by contacting said gases with a slurry of a catalyst composed of palladium or platinum and cobalt supported on a solid phase is disclosed. The catalyst is prepared by heating a heterogeneous component of the palladium or platinum deposited on the solid support in a solution of cobalt carbonyl or precursors thereof. The catalyst exhibits excellent activity, stability in air, and produces highly desirable product fractions even with dilute gaseous reactants.

Agreement between commercial assays for haptoglobin and serum amyloid A in goats.

PubMed

Czopowicz, Michał; Szaluś-Jordanow, Olga; Mickiewicz, Marcin; Moroz, Agata; Witkowski, Lucjan; Markowska-Daniel, Iwona; Reczyńska, Daria; Bagnicka, Emilia; Kaba, Jarosław

2017-10-02

Haptoglobin (Hp) and serum amyloid A (SAA) are considered as the major acute phase proteins (APPs) in goats. These APPs have been investigated in several studies during the last decade. In most studies, a colorimetric assay for Hp and a solid phase sandwich ELISA for SAA have been used for quantification. In 2015, reference intervals for APPs were determined using a new type of assay, the competitive ELISA (cELISA). Results obtained by the cELISA differed significantly from results obtained by previously used assays. The present study aimed to assess the agreement between so far used assays and cELISAs. Sera of 152 female dairy goats of two Polish national breeds were analysed. The concentration of Hp was determined using a colorimetric assay (Hp-CA) and the cELISA (Hp-cELISA), while a solid phase sandwich ELISA (SAA-sELISA) and the cELISA (SAA-cELISA) were used to measure SAA. Agreement between test results was assessed by preparing Bland-Altman plots, and analyzing 95% limits of agreement (LoA). Finally, the assays for Hp and SAA were compared using 147 and 138 serum samples, respectively, as 5 and 14 paired measurements, respectively, were excluded from agreement analyses to avoid extrapolation of Hp and SAA concentration. Measurements obtained by the Hp-CA and Hp-cELISA showed weak positive correlation (r = 0.24, P = 0.003). Limits of agreement (LoA) ranged from + 1.6 (95% CI 1.4 to 1.8) g/L to - 1.5 (95% CI - 1.7 to - 1.3) g/L. Measurements yielded by the SAA-sELISA and SAA-cELISA did not correlate (r = - 0.01, P = 0.855). LoA ranged from + 14.5 mg/L (95% CI 12.9 to 16.1) to - 8.5 mg/L (95% CI - 10.1 to - 6.9). Agreement between the two types of commercial assays for determination of Hp and SAA concentrations in goats is poor and cELISAs tend to underrate both Hp and SAA concentrations.

Collapse of surface nanobubbles.

PubMed

Chan, Chon U; Chen, Longquan; Arora, Manish; Ohl, Claus-Dieter

2015-03-20

Surface attached nanobubbles populate surfaces submerged in water. These nanobubbles have a much larger contact angle and longer lifetime than predicted by classical theory. Moreover, it is difficult to distinguish them from hydrophobic droplets, e.g., polymeric contamination, using standard atomic force microscopy. Here, we report fast dynamics of a three phase contact line moving over surface nanobubbles, polymeric droplets, and hydrophobic particles. The dynamics is distinct: across polymeric droplets the contact line quickly jumps and hydrophobic particles pin the contact line, while surface nanobubbles rapidly shrink once merging with the contact line, suggesting a method to differentiate nanoscopic gaseous, liquid, and solid structures. Although the collapse process of surface nanobubbles occurs within a few milliseconds, we show that it is dominated by microscopic dynamics rather than bulk hydrodynamics.

Potentiometric Aptasensing of Vibrio alginolyticus Based on DNA Nanostructure-Modified Magnetic Beads

PubMed Central

Zhao, Guangtao; Ding, Jiawang; Yu, Han; Yin, Tanji; Qin, Wei

2016-01-01

A potentiometric aptasensing assay that couples the DNA nanostructure-modified magnetic beads with a solid-contact polycation-sensitive membrane electrode for the detection of Vibrio alginolyticus is herein described. The DNA nanostructure-modified magnetic beads are used for amplification of the potential response and elimination of the interfering effect from a complex sample matrix. The solid-contact polycation-sensitive membrane electrode using protamine as an indicator is employed to chronopotentiometrically detect the change in the charge or DNA concentration on the magnetic beads, which is induced by the interaction between Vibrio alginolyticus and the aptamer on the DNA nanostructures. The present potentiometric aptasensing method shows a linear range of 10–100 CFU mL−1 with a detection limit of 10 CFU mL−1, and a good specificity for the detection of Vibrio alginolyticus. This proposed strategy can be used for the detection of other microorganisms by changing the aptamers in the DNA nanostructures. PMID:27918423

Detection of anticentromere antibodies using cloned autoantigen CENP-B.

PubMed

Rothfield, N; Whitaker, D; Bordwell, B; Weiner, E; Senecal, J L; Earnshaw, W

1987-12-01

A solid-phase enzyme-linked immunosorbent assay has been established using a cloned fusion protein, CtermCENP-B [beta-gal], as antigen. The fusion protein carries the major epitope of CENP-B, the major centromeric autoantigen. The enzyme-linked immunosorbent assay was more sensitive than immunofluorescence techniques in detecting anticentromere antibodies in patients with scleroderma or Raynaud's disease, and was weakly positive in 3% of normal controls and in 3% of 70 patients with other connective tissue diseases.

Effect of various electrokinetic treatment regimes on solids surface properties and thermal behavior of oil sediments.

PubMed

Kariminezhad, Esmaeel; Elektorowicz, Maria

2018-04-10

The electrokinetic process has shown its ability to separate the different material phases. However, not much is known about the effect of the electric fields on the surface properties of solids in the oil sediments and their behavior under different electrical regimes. In this study, the effect of four different types of electrical current on the surface properties of oil sediments was investigated, namely constant direct current (CDC), pulsed direct current (PDC), incremental direct current (IDC) and decremental direct current (DDC). X-ray photoelectron spectroscopy (XPS) analyses showed a decrease in the concentration of carbon from 99% in centrifuged samples to 63% on the surface of the solids in the PDC-treated oil sediment. Wettability alteration and contact angle studies showed an enhance in hydrophilicity of the solids following electrokinetic treatment. A significant change in carbon and oxygen-containing functionalities at the surface solids of the DDC-treated sediment was also observed. Thermogravimetric analyses (TGA) confirmed the ability of electrokinetic treatment in separating the phases by shifting the thermogram profiles towards lower temperatures. The findings showed that the electrokinetic process exerts its effect by altering the surface properties of the sediment solids and destabilizing water-in-oil emulsions to facilitate phase separation of this complex waste. Copyright © 2018 Elsevier B.V. All rights reserved.

Relaxation of contact-line singularities solely by the Kelvin effect and apparent contact angles for isothermal volatile liquids in contact with air

NASA Astrophysics Data System (ADS)

Rednikov, Alexey; Colinet, Pierre

2013-11-01

The contact (triple) line of a volatile liquid on a flat solid is studied theoretically. Like with a pure-vapor atmosphere [Phys. Rev. E 87, 010401, 2013], but here for isothermal diffusion-limited evaporation/condensation in the presence of an inert gas, we rigorously show that the notorious contact-line singularities (related to motion or phase change itself) can be regularized solely on account of the Kelvin effect (curvature dependence of the saturation conditions). No disjoining pressure, precursor films or Navier slip are in fact needed to this purpose, and nor are they taken into consideration here (``minimalist'' approach). The model applies to both perfect (zero Young's angle) and partial wetting, and is in particular used to study the related issue of evaporation-induced contact angles. Their modification by the contact-line motion (either advancing or receding) is assessed. The formulation is posed for a distinguished immediate vicinity of the contact line (the ``microregion''), the corresponding problem decoupling to leading order, here up to one unknown coefficient, from what actually happens at the macroscale. The lubrication approximation (implying sufficiently small contact angles) is used in the liquid, coupled with the diffusion equation in the gaz phase. Supported by ESA and BELSPO PRODEX and F.R.S.-FNRS.

Two-dimensional simulation of a two-phase, regenerative pumped radiator loop utilizing direct contact heat transfer with phase change

NASA Astrophysics Data System (ADS)

Rhee, Hyop S.; Begg, Lester L.; Wetch, Joseph R.; Jang, Jong H.; Juhasz, Albert J.

An innovative pumped loop concept for 600 K space power system radiators utilizing direct contact heat transfer, which facilitates repeated startup/shutdown of the power system without complex and time-consuming coolant thawing during power startup, is under development. The heat transfer process with melting/freezing of Li in an NaK flow was studied through two-dimensional time-dependent numerical simulations to characterize and predict the Li/NaK radiator performance during startup (thawing) and shutdown (cold-trapping). Effects of system parameters and the criteria for the plugging domain are presented together with temperature distribution patterns in solid Li and subsequent melting surface profile variations in time.

Evidence for phase separation of ethanol-water mixtures at the hydrogen terminated nanocrystalline diamond surface.

PubMed

Janssens, Stoffel D; Drijkoningen, Sien; Saitner, Marc; Boyen, Hans-Gerd; Wagner, Patrick; Larsson, Karin; Haenen, Ken

2012-07-28

Interactions between ethanol-water mixtures and a hydrophobic hydrogen terminated nanocrystalline diamond surface, are investigated by sessile drop contact angle measurements. The surface free energy of the hydrophobic surface, obtained with pure liquids, differs strongly from values obtained by ethanol-water mixtures. Here, a model which explains this difference is presented. The model suggests that, due to a higher affinity of ethanol for the hydrophobic surface, when compared to water, a phase separation occurs when a mixture of both liquids is in contact with the H-terminated diamond surface. These results are supported by a computational study giving insight in the affinity and related interaction at the liquid-solid interface.

Headspace solid-phase microextraction and gas chromatographic analysis of low-molecular-weight sulfur volatiles with pulsed flame photometric detection and quantification by a stable isotope dilution assay.

PubMed

Ullrich, Sebastian; Neef, Sylvia K; Schmarr, Hans-Georg

2018-02-01

Low-molecular-weight volatile sulfur compounds such as thiols, sulfides, disulfides as well as thioacetates cause a sulfidic off-flavor in wines even at low concentration levels. The proposed analytical method for quantification of these compounds in wine is based on headspace solid-phase microextraction, followed by gas chromatographic analysis with sulfur-specific detection using a pulsed flame photometric detector. Robust quantification was achieved via a stable isotope dilution assay using commercial and synthesized deuterated isotopic standards. The necessary chromatographic separation of analytes and isotopic standards benefits from the inverse isotope effect realized on an apolar polydimethylsiloxane stationary phase of increased film thickness. Interferences with sulfur-specific detection in wine caused by sulfur dioxide were minimized by addition of propanal. The method provides adequate validation data, with good repeatability and limits of detection and quantification. It suits the requirements of wine quality management, allowing the control of oenological treatments to counteract an eventual formation of excessively high concentration of such malodorous compounds. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solid-phase synthesis of smac peptidomimetics incorporating triazoloprolines and biarylalanines.

PubMed

Le Quement, Sebastian T; Ishoey, Mette; Petersen, Mette T; Thastrup, Jacob; Hagel, Grith; Nielsen, Thomas E

2011-11-14

Apoptotic induction mechanisms are of crucial importance for the general homeostasis of multicellular organisms. In cancer the apoptotic pathways are downregulated, which, at least partly, is due to an abundance of inhibitors of apoptosis proteins (IAPs) that block the apoptotic cascade by deactivating proteolytic caspases. The Smac protein has an antagonistic effect on IAPs, thus providing structural clues for the synthesis of new pro-apoptotic compounds. Herein, we report a solid-phase approach for the synthesis of Smac-derived tetrapeptide libraries. On the basis of a common (N-Me)AVPF sequence, peptides incorporating triazoloprolines and biarylalanines were synthesized by means of Cu(I)-catalyzed azide-alkyne cycloaddition and Pd-catalyzed Suzuki cross-coupling reactions. Solid-phase procedures were optimized to high efficiency, thus accessing all products in excellent crude purities and yields (both typically above 90%). The peptides were subjected to biological evaluation in a live/dead cellular assay which revealed that structural decorations on the AVPF sequence indeed are highly important for cytotoxicity toward HeLa cells.

[Simultaneous determination of ten benzotriazole ultraviolet stabilizers in food contact plastic materials by solid phase extraction and ultra performance liquid chromatography with tandem mass spectrometry].

PubMed

Gou, Xinlei; Zhao, Xinying; Chi, Haitao; Gao, Xia; Zhou, Mingqiang; Liu, Weili

2015-06-01

A sensitive method was developed for the simultaneous determination of ten benzotriazole ultraviolet stabilizers in food contact plastic materials by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The sample was extracted by methanol-dichloromethane, and purified by a C18 solid-phase extraction (SPE) column. The separation was performed by using water containing 0. 1% (v/v) formic acid and methanol as the mobile phases with gradient elution at a flow rate of 0. 3 mL/min. The electrospray ionization (ESI) source in positive ion mode was used for the analysis of the ten benzotriazole ultraviolet stabilizers in multiple reaction monitoring (MRM) mode. The results showed that the standard curves were obtained with good correlation coefficients (r2 > 0.996) in their linear concentration ranges. The limits of detection (LODs, S/N = 3) for the ten benzotriazole ultraviolet stabilizers were in the range of 0.6-1.6 µg/kg. The mean recoveries for the ten benzotriazole ultraviolet stabilizers at three spiked levels (low, medium and high) were 75.2%-85.3% with relative standard deviations of 1.0%-5.7%. Ten kinds of food contact plastic materials were tested, and 2,2'-methylenebis (6-(benzotriazol-2-yl)-4-tert-octylphenol) (UV-360) was found in a sample of polyethylene (PE) material. The method is accurate, simple, rapid and feasible for the simultaneous determination of benzotriazole ultraviolet stabilizers in food plastic materials.

Surfactant Facilitated Spreading of Aqueous Drops on Hydrophobic Surfaces

NASA Technical Reports Server (NTRS)

Kumar, Nitin; Couzis, Alex; Maldarelli, Charles; Singh, Bhim S. (Technical Monitor)

2000-01-01

Microgravity technologies often require aqueous phases to spread over nonwetting hydrophobic solid/surfaces. At a hydrophobic surface, the air/hydrophobic solid tension is low, and the solid/aqueous tension is high. A large contact angle forms as the aqueous/air tension acts together with the solid/air tension to balance the large solid/aqueous tension. The aqueous phase, instead of spreading, is held in a meniscus by the large angle. Surfactants facilitate the wetting of water on hydrophobic surfaces by adsorbing on the water/air and hydrophobic solid/water interfaces and lowering the surface tensions of these interfaces. The tension reductions decrease the contact angle, which increases the equilibrium wetted area. Hydrocarbon surfactants (i.e. amphiphiles with a hydrophobic chain of methylene groups attached to a large polar group to give aqueous solubility) do not reduce significantly the contact angles of the very hydrophobic surfaces such as parafilm or polyethylene. Trisiloxane surfactants (amphiphiles with a hydrophobe consisting of methyl groups linked to a trisiloxane backbone in the form of a disk ((CH3)3-Si-O-Si-O-Si(CH3)3)) and an extended ethoxylate (-(OCH2CH2)n-) polar group in the form of a chain with seven or eight units) can significantly reduce the contact angle of water on a very hydrophobic surface and cause rapid and complete (or nearly complete) spreading (lermed superspreading). The overall goal of the research described in this proposal is to establish and verify a theory for how trisiloxanes cause superspreading, and then use this knowledge as a guide to developing more general hydrocarbon based surfactant systems which superspread and can be used in microgravity. We propose that the trisiloxane surfactants superspread when the siloxane adsorbs, the hydrophobic disk parts of the molecule adsorb onto the surface removing the surface water. Since the cross sectional area of the disk is larger than that of the extended ethoxylate chain, the disks can form a space filling mat on the surface which removes a significant amount of the surface water. The water adjacent to the hydrophobic solid surface is of high energy due to incomplete hydrogen bonding; its removal significantly lowers the tension and reduces the contact angle. Hydrocarbon surfactants cannot remove as much surface water because their large polar groups prevent the chains from cohering lengthwise. In our report last year we presented a poster describing the preparation of model very hydrophobic surfaces which are homogeneous and atomically smooth using self assembled monolayers of octadecyl trichlorosilane (OTS). In this poster we will use these surfaces as test substrates in developing hydrocarbon based surfactant systems which superspread. We studied a binary hydrocarbon surfactant systems consisting of a very soluble large polar group polyethylene oxide surfactant (C12E6 (CH3(CH2)11(OCH2CH2)6OH) and a long chain alcohol dodecanol. By mixing the alcohol with this soluble surfactant we have found that the contact angle of the mixed system on our test hydrophobic surfaces is very low. We hypothesize that the alcohol fills in the gaps between adjacent adsorbed chains of the large polar group surfactant. This filling in removes the surface water and effects the decrease in contact angle. We confirm this hypothesis by demonstrating that at the air/water interface the mixed layer forms condensed phases while the soluble large polar group surfactant by itself does not. We present drop impact experiments which demonstrate that the dodecanol/C12E6 mixture is effective in causing impacting drops to spread on the very hydrophobic model OTS surfaces.

Interfacial transduction of nucleic acid hybridization using immobilized quantum dots as donors in fluorescence resonance energy transfer.

PubMed

Algar, W Russ; Krull, Ulrich J

2009-01-06

Fluorescence resonance energy transfer (FRET) using immobilized quantum dots (QDs) as energy donors was explored as a transduction method for the detection of nucleic acid hybridization at an interface. This research was motivated by the success of the QD-FRET-based transduction of nucleic acid hybridization in solution-phase assays. This new work represents a fundamental step toward the assembly of a biosensor, where immobilization of the selective chemistry on a surface is desired. After immobilizing QD-probe oligonucleotide conjugates on optical fibers, a demonstration of the retention of selectivity was achieved by the introduction of acceptor (Cy3)-labeled single-stranded target oligonucleotides. Hybridization generated the proximity required for FRET, and the resulting fluorescence spectra provided an analytical signal proportional to the amount of target. This research provides an important framework for the future development of nucleic acid biosensors based on QDs and FRET. The most important findings of this work are that (1) a QD-FRET solid-phase hybridization assay is viable and (2) a passivating layer of denatured bovine serum albumin alleviates nonspecific adsorption, ultimately resulting in (3) the potential for a reusable assay format and mismatch discrimination. In this, the first incarnation of a solid-phase QD-FRET hybridization assay, the limit of detection was found to be 5 nM, and the dynamic range was almost 2 orders of magnitude. Selective discrimination of the target was shown using a three-base-pairs mismatch from a fully complementary sequence. Despite a gradual loss of signal, reuse of the optical fibers over multiple cycles of hybridization and dehybridization was possible. Directions for further improvement of the analytical performance by optimizing the design of the QD-probe oligonucleotide interface are identified.

Development of a Direct Contact Heat Exchanger, Phase 1 Study Report

NASA Technical Reports Server (NTRS)

Manvi, R.

1978-01-01

Electric power generation from geothermal brine requires, first, bringing the hot brine to the surface and then converting the heat to electric power. Binary conversion schemes were proposed, with the heat transfer between the brine and the working organic fluid taking place in a conventional tube and shell heat exchanger. If the brine is heavily laden with dissolved solids, however, solids buildup on the heat exchanger surfaces leads to a considerable degree of fouling and an accompanying drop in performance is experienced. A possible solution to this problem is the use of a direct contact exchanger with the secondary fluid power cycle. The proposed concept involves the formation of fluid sheets and bells as heat angles. Results of a study concerning the fluid mechanics of such surfaces are given.

Method for separating mono- and di-octylphenyl phosphoric acid esters

DOEpatents

Arnold, Jr., Wesley D.

1977-01-01

A method for separating mono-octylphenyl phosphoric acid ester and di-octylphenyl phosphoric acid ester from a mixture thereof comprises reacting the ester mixture with a source of lithium or sodium ions to form a mixture of the phosphate salts; contacting the salt mixture with an organic solvent which causes the dioctylphenyl phosphate salt to be dissolved in the organic solvent phase and the mono-octylphenyl phosphate salt to exist in a solid phase; separating the phases; recovering the phosphate salts from their respective phases; and acidifying the recovered salts to form the original phosphoric acid esters.

Bacterial toxicity assessment of drinking water treatment residue (DWTR) and lake sediment amended with DWTR.

PubMed

Yuan, Nannan; Wang, Changhui; Pei, Yuansheng

2016-11-01

Drinking water treatment residue (DWTR) seems to be very promising for controlling lake sediment pollution. Logically, acquisition of the potential toxicity of DWTR will be beneficial for its applications. In this study, the toxicity of DWTR and sediments amended with DWTR to Aliivibrio fischeri was evaluated based on the Microtox(®) solid and leachate phase assays, in combination with flow cytometry analyses and the kinetic luminescent bacteria test. The results showed that both solid particles and aqueous/organic extracts of DWTR exhibited no toxicity to the bacterial luminescence and growth. The solid particles of DWTR even promoted bacterial luminescence, possibly because DWTR particles could act as a microbial carrier and provide nutrients for bacteria growth. Bacterial toxicity (either luminescence or growth) was observed from the solid phase and aqueous/organic extracts of sediments with or without DWTR addition. Further analysis showed that the solid phase toxicity was determined to be related mainly to the fixation of bacteria to fine particles and/or organic matter, and all of the observed inhibition resulting from aqueous/organic extracts was identified as non-significant. Moreover, DWTR addition not only had no adverse effect on the aqueous/organic extract toxicity of the sediment but also reduced the solid phase toxicity of the sediment. Overall, in practical application, the solid particles, the water-soluble substances transferred to surface water or the organic substances in DWTR had no toxicity or any delayed effect on bacteria in lakes, and DWTR can therefore be considered as a non-hazardous material. Copyright © 2016 Elsevier Ltd. All rights reserved.

New immobilisation protocol for the template used in solid-phase synthesis of MIP nanoparticles

NASA Astrophysics Data System (ADS)

Chen, Lu; Muhammad, Turghun; Yakup, Burabiye; Piletsky, Sergey A.

2017-06-01

As a novel imprinting method, solid-phase synthesis has proven to be a promising approach to prepare polymer nanoparticles with specific recognition sites for a template molecule. In this method, imprinted polymer nanoparticles were synthesized using template immobilized on a solid support. Herein, preparation of immobilized templates on quartz chips through homogeneous route was reported as an efficient alternative strategy to heterogeneous one. The template molecule indole-3-butyric acid (IBA) was reacted with 3-aminopropyltriethoxysilane (APTES) to produce silylated template (IBA-APTES), and it was characterized by IR, 1H NMR and GC-MS. Then, the silylated template molecule was grafted onto the activated surfaces of quartz chip to prepare immobilized template (SiO2@IBA-APTES). The immobilization was confirmed by contact angle, XPS, UV and fluorescence measurement. Immobilization protocol has shown good reproducibility and stability of the immobilized template. MIP nanoparticles were prepared with high selectivity toward the molecule immobilized onto the solid surface. This provides a new approach for the development of molecularly imprinted nanoparticles.

Formation of target-specific binding sites in enzymes: solid-phase molecular imprinting of HRP.

PubMed

Czulak, J; Guerreiro, A; Metran, K; Canfarotta, F; Goddard, A; Cowan, R H; Trochimczuk, A W; Piletsky, S

2016-06-07

Here we introduce a new concept for synthesising molecularly imprinted nanoparticles by using proteins as macro-functional monomers. For a proof-of-concept, a model enzyme (HRP) was cross-linked using glutaraldehyde in the presence of glass beads (solid-phase) bearing immobilized templates such as vancomycin and ampicillin. The cross-linking process links together proteins and protein chains, which in the presence of templates leads to the formation of permanent target-specific recognition sites without adverse effects on the enzymatic activity. Unlike complex protein engineering approaches commonly employed to generate affinity proteins, the method proposed can be used to produce protein-based ligands in a short time period using native protein molecules. These affinity materials are potentially useful tools especially for assays since they combine the catalytic properties of enzymes (for signaling) and molecular recognition properties of antibodies. We demonstrate this concept in an ELISA-format assay where HRP imprinted with vancomycin and ampicillin replaced traditional enzyme-antibody conjugates for selective detection of templates at micromolar concentrations. This approach can potentially provide a fast alternative to raising antibodies for targets that do not require high assay sensitivities; it can also find uses as a biochemical research tool, as a possible replacement for immunoperoxidase-conjugates.

Molecular transport and flow past hard and soft surfaces: computer simulation of model systems.

PubMed

Léonforte, F; Servantie, J; Pastorino, C; Müller, M

2011-05-11

The equilibrium and flow of polymer films and drops past a surface are characterized by the interface and surface tensions, viscosity, slip length and hydrodynamic boundary position. These parameters of the continuum description are extracted from molecular simulations of coarse-grained models. Hard, corrugated substrates are modelled by a Lennard-Jones solid while polymer brushes are studied as prototypes of soft, deformable surfaces. Four observations are discussed. (i) If the surface becomes strongly attractive or is coated with a brush, the Navier boundary condition fails to describe the effect of the surface independently of the strength and type of the flow. This failure stems from the formation of a boundary layer with an effective, higher viscosity. (ii) In the case of brush-coated surfaces, flow induces a cyclic, tumbling motion of the tethered chain molecules. Their collective motion gives rise to an inversion of the flow in the vicinity of the grafting surfaces and leads to strong, non-Gaussian fluctuations of the molecular orientations. The flow past a polymer brush cannot be described by Brinkman's equation. (iii) The hydrodynamic boundary condition is an important parameter for predicting the motion of polymer droplets on a surface under the influence of an external force. Their steady-state velocity is dictated by a balance between the power that is provided by the external force and the dissipation. If there is slippage at the liquid-solid interface, the friction at the solid-liquid interface and the viscous dissipation of the flow inside the drop will be the dominant dissipation mechanisms; dissipation at the three-phase contact line appears to be less important on a hard surface. (iv) On a soft, deformable substrate like a polymer brush, we observe a lifting-up of the three-phase contact line. Controlling the grafting density and the incompatibility between the brush and the polymer liquid we can independently tune the softness of the surface and the contact angle and thereby identify the parameters for maximizing the deformation at the three-phase contact.

An energy-based equilibrium contact angle boundary condition on jagged surfaces for phase-field methods.

PubMed

Frank, Florian; Liu, Chen; Scanziani, Alessio; Alpak, Faruk O; Riviere, Beatrice

2018-08-01

We consider an energy-based boundary condition to impose an equilibrium wetting angle for the Cahn-Hilliard-Navier-Stokes phase-field model on voxel-set-type computational domains. These domains typically stem from μCT (micro computed tomography) imaging of porous rock and approximate a (on μm scale) smooth domain with a certain resolution. Planar surfaces that are perpendicular to the main axes are naturally approximated by a layer of voxels. However, planar surfaces in any other directions and curved surfaces yield a jagged/topologically rough surface approximation by voxels. For the standard Cahn-Hilliard formulation, where the contact angle between the diffuse interface and the domain boundary (fluid-solid interface/wall) is 90°, jagged surfaces have no impact on the contact angle. However, a prescribed contact angle smaller or larger than 90° on jagged voxel surfaces is amplified. As a remedy, we propose the introduction of surface energy correction factors for each fluid-solid voxel face that counterbalance the difference of the voxel-set surface area with the underlying smooth one. The discretization of the model equations is performed with the discontinuous Galerkin method. However, the presented semi-analytical approach of correcting the surface energy is equally applicable to other direct numerical methods such as finite elements, finite volumes, or finite differences, since the correction factors appear in the strong formulation of the model. Copyright © 2018 Elsevier Inc. All rights reserved.

Impact of the volume of gaseous phase in closed reactors on ANC results and modelling

NASA Astrophysics Data System (ADS)

Drapeau, Clémentine; Delolme, Cécile; Lassabatere, Laurent; Blanc, Denise

2016-04-01

The understanding of the geochemical behavior of polluted solid materials is often challenging and requires huge expenses of time and money. Nevertheless, given the increasing amounts of polluted solid materials and related risks for the environment, it is more and more crucial to understand the leaching of majors and trace metals elements from these matrices. In the designs of methods to quantify pollutant solubilization, the combination of experimental procedures with modeling approaches has recently gained attention. Among usual methods, some rely on the association of ANC and geochemical modeling. ANC experiments - Acid Neutralization Capacity - consists in adding known quantities of acid or base to a mixture of water and contaminated solid materials at a given liquid / solid ratio in closed reactors. Reactors are agitated for 48h and then pH, conductivity, redox potential, carbon, majors and heavy metal solubilized are quantified. However, in most cases, the amounts of matrix and water do not reach the total volume of reactors, leaving some space for air (gaseous phase). Despite this fact, no clear indication is given in standard procedures about the effect of this gaseous phase. Even worse, the gaseous phase is never accounted for when exploiting or modeling ANC data. The gaseous phase may exchange CO2 with the solution, which may, in turn, impact both pH and element release. This study lies within the most general framework for the use of geochemical modeling for the prediction of ANC results for the case of pure phases to real phase assemblages. In this study, we focus on the effect of the gaseous phase on ANC experiments on different mineral phases through geochemical modeling. To do so, we use PHREEQC code to model the evolution of pH and element release (including majors and heavy metals) when several matrices are put in contact with acid or base. We model the following scenarios for the gaseous phase: no gas, contact with the atmosphere (open system) and real reactors conditions (semi-closed systems). The solid phases tested are pure phases (calcite, sulfides, etc.) and synthetic assemblages mimicking complex polluted matrices. The modeling clearly shows that the systems are sensitive to the opening to the atmosphere. If the open system and the system with no gas are entirely different, "real" reactors also differ significantly from the other systems. Apparently, the presence of the gaseous phase in reactors greatly impacts pH and element release. This parameter should be accounted for in ANC experimental procedures and modeling. In addition to this numerical study, experimental results, previously obtained for urban polluted sediments, are analyzed in lights of the findings of the numerical study. This step allows us to strengthen conclusions and to pinpoint at the necessity to account for the gaseous phase when performing and modeling ANC experiments.

Tribological properties of surfaces

NASA Technical Reports Server (NTRS)

Buckley, D. H.

1978-01-01

The real area of contact between two solid surfaces is only a small portion of the apparent area. Deformation of these areas can result in solid state contact through surface films. For clean solid to solid contact strong adhesive bonding occurs across the interface. Under these conditions many properties of the solid such as the metallurgical and chemical nature of metals can influence adhesion, friction, and wear behavior. The presence of gases, liquids, and solid films on the surface of solids alter markedly tribological characteristics. These surface films can also considerably change the mechanical effects of solid state contact on bulk material behavior.

[Acaricidal activity of clove bud oil against Dermatophagoides farinae (Acari: Pyroglyphidae)].

PubMed

Li, Jing; Wu, Hai-Qiang; Liu, Zhi-Gang

2009-12-01

Volatile oil from the clove bud was extracted by petroleum ether using Soxhlet Extractor. The acaricidal activity was examined using direct contact and vapour phase toxicity bioassays. In a filter paper contact toxicity bio-assay, at 2.5 h after treatment, clove bud oil at a dose of 12.20 microg/cm2 killed all dust mites. As judged by 24-h LD50 values, potent fumigant action was observed with clove bud oil (12.20 microg/cm2), showing an adequate acaricidal activity against indoor Dermatophagoides farinae.

Determination of vigabatrin in human plasma and urine by high-performance liquid chromatography with fluorescence detection.

PubMed

Erturk, S; Aktas, E S; Atmaca, S

2001-09-05

A sensitive and specific HPLC method has been developed for the assay of vigabatrin in human plasma and urine. The assay involves derivatization with 4-chloro-7-nitrobenzofurazan, solid-phase extraction on a silica column and isocratic reversed-phase chromatography with fluorescence detection. Aspartam was used as an internal standard. The assay was linear over the concentration range of 0.2-20.0 microg/ml for plasma and 1.0-15.0 microg/ml for urine with a lower limit of detection of 0.1 microg/ml using 0.1 ml of starting volume of the sample. Both the within-day and day-to-day reproducibilities and accuracies were less than 5.46% and 1.6%, respectively. After a single oral dose of 500 mg of vigabatrin, the plasma concentration and the cumulative urinary excretion of the drug were determined.

Wetting in a Colloidal Liquid-Gas System

NASA Astrophysics Data System (ADS)

Wijting, W. K.; Besseling, N. A.; Stuart, M. A.

2003-05-01

We present first observations of wetting phenomena in depletion interaction driven, phase separated colloidal dispersions (coated silica cyclohexane-polydimethylsiloxane). The contact angle of the colloidal liquid-gas interface at a solid substrate (coated glass) was determined for a series of compositions. Upon approach to the critical point, a transition occurs from partial to complete wetting.

Wetting in a colloidal liquid-gas system.

PubMed

Wijting, W K; Besseling, N A M; Stuart, M A Cohen

2003-05-16

We present first observations of wetting phenomena in depletion interaction driven, phase separated colloidal dispersions (coated silica-cyclohexane-polydimethylsiloxane). The contact angle of the colloidal liquid-gas interface at a solid substrate (coated glass) was determined for a series of compositions. Upon approach to the critical point, a transition occurs from partial to complete wetting.

Effect of nanostructure on rapid boiling of water on a hot copper plate: a molecular dynamics study

NASA Astrophysics Data System (ADS)

Fu, Ting; Mao, Yijin; Tang, Yong; Zhang, Yuwen; Yuan, Wei

2016-08-01

Molecular dynamic simulations are performed to study the effects of nanostructure on rapid boiling of water that is suddenly heated by a hot copper plate. The results show that the nanostructure has significant effects on energy transfer from solid copper plate to liquid water and phase change process from liquid water to vapor. The liquid water on the solid surface rapidly boil after contacting with an extremely hot copper plate and consequently a cluster of liquid water moves upward during phase change. The temperature of the water film when it separates from solid surface and its final temperature when the system is at equilibrium strongly depend on the size of the nanostructure. These temperatures increase with increasing size of nanostructure. Furthermore, a non-vaporized molecular layer is formed on the surface of the copper plate even continuous heat flux is passing into water domain through the plate.

Enhancing Modulation of Thermal Conduction in Vanadium Dioxide Thin Film by Nanostructured Nanogaps

DOE PAGES

Choe, Hwan Sung; Suh, Joonki; Ko, Changhyun; ...

2017-08-02

Efficient thermal management at the nanoscale is important for reducing energy consumption and dissipation in electronic devices, lab-on-a-chip platforms and energy harvest/conversion systems. For many of these applications, it is much desired to have a solid-state structure that reversibly switches thermal conduction with high ON/OFF ratios and at high speed. We describe design and implementation of a novel, all-solid-state thermal switching device by nanostructured phase transformation, i.e., modulation of contact pressure an d area between two poly-silicon surfaces activated by microstructural change of a vanadium dioxide (VO 2 ) thin film. Our solid-state devices demonstrate large and reversible alteration ofmore » cross-plane thermal conductance as a function of temperature, achieving a conductance ratio of at least 2.5. This new approach using nanostructured phase transformation provides new opportunities for applications that require advanced temperature and heat regulations.« less

Enhancing Modulation of Thermal Conduction in Vanadium Dioxide Thin Film by Nanostructured Nanogaps

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choe, Hwan Sung; Suh, Joonki; Ko, Changhyun

Efficient thermal management at the nanoscale is important for reducing energy consumption and dissipation in electronic devices, lab-on-a-chip platforms and energy harvest/conversion systems. For many of these applications, it is much desired to have a solid-state structure that reversibly switches thermal conduction with high ON/OFF ratios and at high speed. We describe design and implementation of a novel, all-solid-state thermal switching device by nanostructured phase transformation, i.e., modulation of contact pressure an d area between two poly-silicon surfaces activated by microstructural change of a vanadium dioxide (VO 2 ) thin film. Our solid-state devices demonstrate large and reversible alteration ofmore » cross-plane thermal conductance as a function of temperature, achieving a conductance ratio of at least 2.5. This new approach using nanostructured phase transformation provides new opportunities for applications that require advanced temperature and heat regulations.« less

Self-spreading of the wetting ridge during stick-slip on a viscoelastic surface

DOE PAGES

Park, S. J.; Bostwick, J. B.; De Andrade, V.; ...

2017-10-23

Dynamic wetting behaviors on soft solids are important to interpret complex biological processes from cell–substrate interactions. Despite intensive research studies over the past half-century, the underlying mechanisms of spreading behaviors are not clearly understood. The most interesting feature of wetting on soft matter is the formation of a “wetting ridge”, a surface deformation by a competition between elasticity and capillarity. Dynamics of the wetting ridge formed at the three-phase contact line underlies the dynamic wetting behaviors, but remains largely unexplored mostly due to limitations in indirect observation. Here, we directly visualize wetting ridge dynamics during continuous- and stick-slip motions onmore » a viscoelastic surface using X-ray microscopy. Strikingly, we discover that the ridge spreads spontaneously during stick and triggers contact line depinning (stick-to-slip transition) by changing the ridge geometry which weakens the contact line pinning. Finally, we clarify ‘viscoelastic-braking’, ‘stick-slipping’, and ‘stick-breaking’ spreading behaviors through the ridge dynamics. In stick-breaking, no ridge-spreading occurs and contact line pinning (hysteresis) is enhanced by cusp-bending while preserving a microscopic equilibrium at the ridge tip. We have furthered the understanding of spreading behaviors on soft solids and demonstrated the value of X-ray microscopy in elucidating various dynamic wetting behaviors on soft solids as well as puzzling biological issues.« less

Performance evaluation of extractor cutting blade configuration in Inulin extraction process from Dahlia sp. L tuber

NASA Astrophysics Data System (ADS)

Sundari, E.; Praputri, E.; Marthiana, W.; Jaya, M.

2018-03-01

Inulin, a polysaccharide plant-based nutrient, can be isolated from dahlia flower tubers by liquid-solid extraction processes and is generally carried out in an extractor tank equipped with an agitator. To accelerate the diffusion rate of solute from the solid phase (bulk phase) to the external surface (boundary layer) in order to increase yield of inulin, the size reduction of material is required. The purpose of this research was to design the cutting blade needed for dahlia tuber size reduction and investigate the effect of blade types, agitator speed (350, 700, 1050, and 1400 rpm), and configuration of cutting blade to material fineness at 90 minutes of contacting time. The results showed that higher cutting blade speed results in higher cut material fineness rate. The best conditions was achieved by the configuration of two four-blade turbine combined with one three-blade turbine with fineness rate more than 90% in 30 minutes of contacting time at every variation of agitator speed. The cutting blade designed in this study can be used for size reduction purpose of tubers other than dahlia tubers.

Liquid-liquid and solid-phase extractions of phenols from virgin olive oil and their separation by chromatographic and electrophoretic methods.

PubMed

Bendini, Alessandra; Bonoli, Matteo; Cerretani, Lorenzo; Biguzzi, Barbara; Lercker, Giovanni; Toschi, Tullia Gallina

2003-01-24

The high oxidative stability of virgin olive oil is related to its high monounsaturated/polyunsaturated ratio and to the presence of antioxidant compounds, such as tocopherols and phenols. In this paper, the isolation of phenolic compounds from virgin olive oil, by different methods, was tested and discussed. Particularly liquid-liquid and solid-phase extraction methods were compared, assaying, for the latter, three stationary phases (C8, C18 and Diol) and several elution mixtures. Quantification of phenolic and o-diphenolic substances in the extracts was performed by the traditional Folin-Ciocalteau method and the sodium molybdate reaction, respectively. Furthermore, the quantification of phenolic compounds in the extracts and in a standard mixture was carried out both with diode array and mass spectrometric detection and capillary zone electrophoresis.

Method of producing a colloidal fuel from coal and a heavy petroleum fraction. [partial liquefaction of coal in slurry, filtration and gasification of residue

DOEpatents

Longanbach, J.R.

1981-11-13

A method is provided for combining coal as a colloidal suspension within a heavy petroleum fraction. The coal is broken to a medium particle size and is formed into a slurry with a heavy petroleum fraction such as a decanted oil having a boiling point of about 300 to 550/sup 0/C. The slurry is heated to a temperature of 400 to 500/sup 0/C for a limited time of only about 1 to 5 minutes before cooling to a temperature of less than 300/sup 0/C. During this limited contact time at elevated temperature the slurry can be contacted with hydrogen gas to promote conversion. The liquid phase containing dispersed coal solids is filtered from the residual solids and recovered for use as a fuel or feed stock for other processes. The residual solids containing some carbonaceous material are further processed to provide hydrogen gas and heat for use as required in this process.

Computational Fluid Dynamics–Discrete Element Method (CFD-DEM) Study of Mass-Transfer Mechanisms in Riser Flow

PubMed Central

2017-01-01

We report a computational fluid dynamics–discrete element method (CFD-DEM) simulation study on the interplay between mass transfer and a heterogeneous catalyzed chemical reaction in cocurrent gas-particle flows as encountered in risers. Slip velocity, axial gas dispersion, gas bypassing, and particle mixing phenomena have been evaluated under riser flow conditions to study the complex system behavior in detail. The most important factors are found to be directly related to particle cluster formation. Low air-to-solids flux ratios lead to more heterogeneous systems, where the cluster formation is more pronounced and mass transfer more influenced. Falling clusters can be partially circumvented by the gas phase, which therefore does not fully interact with the cluster particles, leading to poor gas–solid contact efficiencies. Cluster gas–solid contact efficiencies are quantified at several gas superficial velocities, reaction rates, and dilution factors in order to gain more insight regarding the influence of clustering phenomena on the performance of riser reactors. PMID:28553011

Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) Study of Mass-Transfer Mechanisms in Riser Flow.

PubMed

Carlos Varas, Álvaro E; Peters, E A J F; Kuipers, J A M

2017-05-17

We report a computational fluid dynamics-discrete element method (CFD-DEM) simulation study on the interplay between mass transfer and a heterogeneous catalyzed chemical reaction in cocurrent gas-particle flows as encountered in risers. Slip velocity, axial gas dispersion, gas bypassing, and particle mixing phenomena have been evaluated under riser flow conditions to study the complex system behavior in detail. The most important factors are found to be directly related to particle cluster formation. Low air-to-solids flux ratios lead to more heterogeneous systems, where the cluster formation is more pronounced and mass transfer more influenced. Falling clusters can be partially circumvented by the gas phase, which therefore does not fully interact with the cluster particles, leading to poor gas-solid contact efficiencies. Cluster gas-solid contact efficiencies are quantified at several gas superficial velocities, reaction rates, and dilution factors in order to gain more insight regarding the influence of clustering phenomena on the performance of riser reactors.

Kinetic precipitation of solution-phase polyoxomolybdate followed by transmission electron microscopy: a window to solution-phase nanostructure.

PubMed

Zhu, Yan; Cammers-Goodwin, Arthur; Zhao, Bin; Dozier, Alan; Dickey, Elizabeth C

2004-05-17

This study aimed to elucidate the structural nature of the polydisperse, nanoscopic components in the solution and the solid states of partially reduced polyoxomolybdate derived from the [Mo132] keplerate, [(Mo)Mo5]12-[Mo2 acetate]30. Designer tripodal hexamine-tris-crown ethers and nanoscopic molybdate coprecipitated from aqueous solution. These microcrystalline solids distributed particle radii between 2-30 nm as assayed by transmission electron microscopy (TEM). The solid materials and their particle size distributions were snap shots of the solution phase. The mother liquor of the preparation of the [Mo132] keplerate after three days revealed large species (r=20-30 nm) in the coprecipitate, whereas [Mo132] keplerate redissolved in water revealed small species (3-7 nm) in the coprecipitate. Nanoparticles of coprecipitate were more stable than solids derived solely from partially reduced molybdate. The TEM features of all material analyzed lacked facets on the nanometer length scale; however, the structures diffracted electrons and appeared to be defect-free as evidenced by Moiré patterns in the TEM images. Moiré patterns and size-invariant optical densities of the features in the micrographs suggested that the molybdate nanoparticles were vesicular.

A solid phase enzyme-linked immunosorbent assay for the antigenic detection of Legionella pneumophila (serogroup 1): A compliment for the space station diagnostic capability

NASA Technical Reports Server (NTRS)

Hejtmancik, Kelly E.

1987-01-01

It is necessary that an adequate microbiology capability be provided as part of the Health Maintenance Facility (HMF) to support expected microbial disease events and environmental monitoring during long periods of space flight. The application of morphological and biochemical studies to confirm the presence of certain bacterial and fungal disease agents are currently available and under consideration. This confirmation would be facilitated through employment of serological methods to aid in the identification of bacterial, fungal, and viral agents. A number of serological approaches are currently being considered, including the use of Enzyme Linked Immunosorbent Assay (ELISA) technology, which could be utilized during microgravity conditions. A solid phase, membrane supported ELISA for the detection of Legionella pneumophila, an expected disease agent, was developed to show a potential model system that would meet the HMF requirements and specifications for the future space station. These studies demonstrate the capability of membrane supported ELISA systems for identification of expected microbial disease agents as part of the HMF.

Calculation of Gallium-metal-Arsenic phase diagrams

NASA Technical Reports Server (NTRS)

Scofield, J. D.; Davison, J. E.; Ray, A. E.; Smith, S. R.

1991-01-01

Electrical contacts and metallization to GaAs solar cells must survive at high temperatures for several minutes under specific mission scenarios. The determination of which metallizations or alloy systems that are able to withstand extreme thermal excursions with minimum degradation to solar cell performance can be predicted by properly calculated temperature constitution phase diagrams. A method for calculating a ternary diagram and its three constituent binary phase diagrams is briefly outlined and ternary phase diagrams for three Ga-As-X alloy systems are presented. Free energy functions of the liquid and solid phase are approximated by the regular solution theory. Phase diagrams calculated using this method are presented for the Ga-As-Ge and Ga-As-Ag systems.

Dynamics of solid lubrication as observed by optical microscopy

NASA Technical Reports Server (NTRS)

Sliney, H. E.

1976-01-01

A bench metallograph was converted into a micro contact imager by the addition of a tribometer employing a steel ball in sliding contact with a glass disk. The sliding contact was viewed in real time by means of projection microscope optics. The dynamics of abrasive particles and of solid lubricant particles within the contact were observed in detail. The contact was characterized by a constantly changing pattern of elastic strain with the passage of surface discontinuities and solid particles. Abrasive particles fragmented upon entering the contact, embedded in one surface and scratched the other; in contrast, the solid lubricant particles flowed plastically into thin films. The rheological behavior of the lubricating solids gave every appearance of a paste-like consistency within the Hertzian contact.

Proliferative responses in the local lymph node assay associated with concomitant exposure to 1,4-phenylenediamine and methyldibromo glutaronitrile: evidence for synergy?

PubMed

Jowsey, Ian R; Basketter, David A; Irwin, Anita

2008-08-01

A key consideration when undertaking risk assessments should be the potential for synergy between contact allergens. Previously, this concept has only been investigated during elicitation in contact allergic individuals. To determine whether there exists evidence for synergy between contact allergens during the induction phase of skin sensitization using the mouse local lymph node assay (LLNA) as a model system. Proliferative responses in draining lymph nodes were assessed with increasing concentrations of 1,4-phenylenediamine (PPD), methyldibromo glutaronitrile (MDBGN), and a combination of PPD and MDBGN. Data from each of two independent experiments show that lymph node cell proliferation associated with combined exposure to PPD and MDBGN was, in general, only modestly increased relative to that predicted from a simple summation of their individual responses. Although the increase in response is very modest, it does imply a relationship between this combination of sensitizers that may not be simply additive in terms of their ability to stimulate proliferative responses in draining lymph nodes. The reproducibility of this observation should be confirmed in future studies with additional pairs of contact allergens to ascertain whether or not this represents evidence of synergy.

Macrophages influence a competition of contact guidance and chemotaxis for fibroblast alignment in a fibrin gel coculture assay.

PubMed

Bromberek, B A; Enever, P A J; Shreiber, D I; Caldwell, M D; Tranquillo, R T

2002-05-01

Rat dermal fibroblasts were dispersed initially in the outer shell of a fibrin gel sphere, while the inner core either was devoid of cells or contained peritoneal exudate cells (primarily macrophages), thereby mimicking the inflammatory phase of wound healing. The fibroblasts compacted floating fibrin microspheres over time. In the absence of macrophages, the initial distribution of fibroblasts (only in the shell) induced circumferential alignment of fibrin fibrils via compaction of the shell relative to the core. The aligned fibrils created a contact guidance field, which was manifested by strong circumferential alignment of the fibroblasts. However, in the presence of macrophages, the fibroblasts exhibited more radial alignment despite the simultaneous contact guidance field in the circumferential direction associated with compaction. This was attributed to a chemotactic gradient emanating from the core due to a putative factor(s) released by the macrophages. The presence of a radial chemotactic stimulus was supported by the finding of even greater radial alignment when fibrin microspheres were embedded in an agarose-fibrin gel that abolished compaction and consequently the contact guidance field. Our assay permits the simulation of tissue morphogenetic processes that involve cell guidance phenomena and tractional restructuring of the extracellular matrix.

Pore-scale modeling of moving contact line problems in immiscible two-phase flow.

NASA Astrophysics Data System (ADS)

Kucala, A.; Noble, D.; Martinez, M. J.

2016-12-01

Two immiscible fluids in static equilibrium form a common interface along a solid surface, characterized as the static contact (wetting) angle and is a function of surface geometry, intermolecular forces, and interfacial surface energies manifested as interfacial tension. This static configuration may become perturbed due to external force imbalances (mass injection, pressure gradients, buoyancy, etc.) and the contact line location and interface curvature becomes dynamic. Accurate modeling of moving contact line (MCL) problems is imperative in predicting capillary pressure vs. saturation curves, permeability, and preferential flow paths for a variety of applications, including geological carbon storage (GCS) and enhanced oil recovery (EOR). Here, we present a model for the moving contact line using pore-scale computational fluid dynamics (CFD) which solves the full, time-dependent Navier-Stokes equations using the Galerkin finite-element method. The MCL is modeled as a surface traction force proportional to the surface tension, dependent on the static properties of the immiscible fluid/solid system. The moving two-phase interface is tracked using the level set method and discretized with the conformal decomposition finite element method (CDFEM), allowing for surface tension effects to be computed at the exact interface location. We present a variety of verification test cases for simple two- and three-dimensional geometries to validate the current model, including threshold pressure predictions in flows through pore-throats for a variety of wetting angles. Simulations involving more complex geometries are also presented to be used in future simulations for GCS and EOR problems. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000

Solid-phase supports for the in situ assembly of quantum dot-FRET hybridization assays in channel microfluidics.

PubMed

Tavares, Anthony J; Noor, M Omair; Uddayasankar, Uvaraj; Krull, Ulrich J; Vannoy, Charles H

2014-01-01

Semiconductor quantum dots (QDs) have long served as integral components in signal transduction modalities such as Förster resonance energy transfer (FRET). The majority of bioanalytical methods using QDs for FRET-based techniques simply monitor binding-induced conformational changes. In more recent work, QDs have been incorporated into solid-phase support systems, such as microfluidic chips, to serve as physical platforms in the development of functional biosensors and bioprobes. Herein, we describe a simple strategy for the transduction of nucleic acid hybridization that combines a novel design method based on FRET with an electrokinetically controlled microfluidic technology, and that offers further potential for amelioration of sample-handling issues and for simplification of dynamic stringency control.

Mechanisms of single bubble cleaning.

PubMed

Reuter, Fabian; Mettin, Robert

2016-03-01

The dynamics of collapsing bubbles close to a flat solid is investigated with respect to its potential for removal of surface attached particles. Individual bubbles are created by nanosecond Nd:YAG laser pulses focused into water close to glass plates contaminated with melamine resin micro-particles. The bubble dynamics is analysed by means of synchronous high-speed recordings. Due to the close solid boundary, the bubble collapses with the well-known liquid jet phenomenon. Subsequent microscopic inspection of the substrates reveals circular areas clean of particles after a single bubble generation and collapse event. The detailed bubble dynamics, as well as the cleaned area size, is characterised by the non-dimensional bubble stand-off γ=d/Rmax, with d: laser focus distance to the solid boundary, and Rmax: maximum bubble radius before collapse. We observe a maximum of clean area at γ≈0.7, a roughly linear decay of the cleaned circle radius for increasing γ, and no cleaning for γ>3.5. As the main mechanism for particle removal, rapid flows at the boundary are identified. Three different cleaning regimes are discussed in relation to γ: (I) For large stand-off, 1.8<γ<3.5, bubble collapse induced vortex flows touch down onto the substrate and remove particles without significant contact of the gas phase. (II) For small distances, γ<1.1, the bubble is in direct contact with the solid. Fast liquid flows at the substrate are driven by the jet impact with its subsequent radial spreading, and by the liquid following the motion of the collapsing and rebounding bubble wall. Both flows remove particles. Their relative timing, which depends sensitively on the exact γ, appears to determine the extension of the area with forces large enough to cause particle detachment. (III) At intermediate stand-off, 1.1<γ<1.8, only the second bubble collapse touches the substrate, but acts with cleaning mechanisms similar to an effective small γ collapse: particles are removed by the jet flow and the flow induced by the bubble wall oscillation. Furthermore, the observations reveal that the extent of direct bubble gas phase contact to the solid is partially smaller than the cleaned area, and it is concluded that three-phase contact line motion is not a major cause of particle removal. Finally, we find a relation of cleaning area vs. stand-off γ that deviates from literature data on surface erosion. This indicates that different effects are responsible for particle removal and for substrate damage. It is suggested that a trade-off of cleaning potential and damage risk for sensible surfaces might be achieved by optimising γ. Copyright © 2015 Elsevier B.V. All rights reserved.

Off-line solid phase extraction and liquid chromatography-tandem mass spectrometry method for the quantitation of brivaracetam acid metabolites: Method validation and application to in vitro metabolism assays.

PubMed

Bourgogne, Emmanuel; Culot, Benoit; Dell'Aiera, Sylvie; Chanteux, Hugues; Stockis, Armel; Nicolas, Jean-Marie

2018-06-01

Brivaracetam (BRV) is a new high affinity synaptic vesicle protein 2A ligand recently approved for adults with partial-onset seizures. As a support to in vitro metabolism assays, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method coupled to off-line solid phase extraction (SPE) was developed to quantify BRV acid metabolites, that is, BRV-AC (carboxylic derivative derived from BRV hydrolysis) and BRV-OHAC (corresponding to hydroxylated BRV-AC). The method was validated for various incubates (liver and kidney tissue homogenates and blood, all from humans) and applied to in vitro metabolism assays. The analytes were isolated from buffered samples using ISOLUTE C8 96-well SPE plates. Chromatographic separation was achieved on a Waters Atlantis T3 C18 analytical column (2.1 mm × 50 mm, 5 μm) with detection accomplished using a Waters Premier tandem mass spectrometer in positive ion electrospray and multiple reaction monitoring (MRM) mode. The standard curves, which ranged from 1.00 to 200 ng/mL for BRV-AC, BRV-OHAC, were fitted to a 1/x 2 weighted linear regression model. The intra-assay precision and inter-assay precision (expressed as coefficient of variation -%CV) were <8.5%, and the assay accuracy (deviation - %Dev) was within ±7.1% for the different matrices. This accurate, precise, and selective SPE/LC-MS/MS method has been successfully applied to in vitro assays aimed at characterizing the kinetics of BRV hydrolysis. BRV was found to be a better substrate for hydrolysis than its hydroxylated metabolite BRV-OH. BRV hydrolysis was detected in blood, liver and kidneys, demonstrating the broad distribution of the enzyme catalyzing the reaction. Copyright © 2018 Elsevier B.V. All rights reserved.

Dynamics of viscous liquid bridges inside microchannels subject to external oscillatory flow

NASA Astrophysics Data System (ADS)

Ahmadlouydarab, Majid; Azaiez, Jalel; Chen, Zhangxin

2015-02-01

We report on two-dimensional simulations of liquid bridges' dynamics inside microchannels of uniform wettability and subject to an external oscillatory flow rate. The oscillatory flow results in a zero net flow rate and its effects are compared to those of a stationary system. To handle the three phase contact lines motion, Cahn-Hilliard diffuse-interface formulation was used and the flow equations were solved using the finite element method with adaptively refined unstructured grids. The results indicate that the liquid bridge responds in three different ways depending on the substrate wettability properties and the frequency of the oscillatory flow. In particular below a critical frequency, the liquid bridge will rupture when the channel walls are philic or detach from the surface when they are phobic. However, at high frequencies, the liquid bridge shows a perpetual periodic oscillatory motion for both philic and phobic surfaces. Furthermore, an increase in the frequency of the flow velocity results in stabilization effects and a behavior approaching that of the stationary system where no rupture or detachment can be observed. This stable behavior is the direct result of less deformation of the liquid bridge due to the fast flow direction change and motion of contact lines on the solid substrate. Moreover, it was found that the flow velocity is out of phase with the footprint and throat lengths and that the latter two also show a phase difference. These differences were explained in terms of the motion of the two contact lines on the solid substrates and the deformation of the two fluid-fluid interfaces.

Dynamics of viscous liquid bridges inside microchannels subject to external oscillatory flow.

PubMed

Ahmadlouydarab, Majid; Azaiez, Jalel; Chen, Zhangxin

2015-02-01

We report on two-dimensional simulations of liquid bridges' dynamics inside microchannels of uniform wettability and subject to an external oscillatory flow rate. The oscillatory flow results in a zero net flow rate and its effects are compared to those of a stationary system. To handle the three phase contact lines motion, Cahn-Hilliard diffuse-interface formulation was used and the flow equations were solved using the finite element method with adaptively refined unstructured grids. The results indicate that the liquid bridge responds in three different ways depending on the substrate wettability properties and the frequency of the oscillatory flow. In particular below a critical frequency, the liquid bridge will rupture when the channel walls are philic or detach from the surface when they are phobic. However, at high frequencies, the liquid bridge shows a perpetual periodic oscillatory motion for both philic and phobic surfaces. Furthermore, an increase in the frequency of the flow velocity results in stabilization effects and a behavior approaching that of the stationary system where no rupture or detachment can be observed. This stable behavior is the direct result of less deformation of the liquid bridge due to the fast flow direction change and motion of contact lines on the solid substrate. Moreover, it was found that the flow velocity is out of phase with the footprint and throat lengths and that the latter two also show a phase difference. These differences were explained in terms of the motion of the two contact lines on the solid substrates and the deformation of the two fluid-fluid interfaces.

Interpreting contact angle results under air, water and oil for the same surfaces

NASA Astrophysics Data System (ADS)

Ozkan, Orkun; Yildirim Erbil, H.

2017-06-01

Under-water and under-oil superhydropobicity and superhydrophilicity have gained significant attention over the last few years. In this study, contact angles on five flat surfaces (polypropylene, poly(methyl methacrylate), polycarbonate, TEFLON-FEP and glass slide) were measured in water drop-in-air, air bubble-under-water, oil drop-in-air, air bubble-under-oil, oil drop-under-water and water drop-under-oil conditions. Heptane, octane, nonane, decane, dodecane, and hexadecane hydrocarbons were used as oils. Immiscible water/oil pairs were previously mutually saturated to provide thermodynamical equilibrium conditions and their surface and interfacial tensions were determined experimentally. These pairs were used in the two-liquid contact angle measurements. Surface free energies of the solid surfaces in air were determined independently by using the van Oss-Good method, using the contact angle results of pure water, ethylene glycol, formamide, methylene iodide and α-bromonaphalene. In addition, Zisman’s ‘critical surface tension’ values were also determined for comparison. In theory, the summation of contact angle results in a complementary case would give a total of 180° for ideal surfaces. However, it was determined that there are large deviations from this rule in practical cases and these deviations depend on surface free energies of solids. Three complementary cases of (water-in-air with air bubble-under-water); (oil-in-air with air bubble-under-oil); and (oil-under-water with water-under-oil) were investigated in particular to determine the deviations from ideality. A novel approach, named ‘complementary hysteresis’ [γ WA(cosθ 1  -  cosθ 2) and γ OW(cosθ 6  -  cosθ 5)] was developed where γ WA and γ OW represent the interfacial tensions of water/air and oil/water, and θ 1, θ 2, θ 5, and θ 6 were the contact angles of water/air, air bubble/water, oil/water and water/oil respectively. It was experimentally determined that complementary hysteresis varies almost linearly with the surface free energy of the flat solid samples. This is the first report showing the relation of the surface free energy of a solid which is determined under-air with the contact angles obtained on the same solid in different three-phase systems.

Liquid-solid equilibria involving spinel, ilmenite, and ferropseudobrookite in the system 'FeO'-Al2O3-TiO2 in contact with metallic iron

NASA Technical Reports Server (NTRS)

Schreifels, W. A.; Muan, A.

1975-01-01

Phase relations in the liquidus temperature region of the system 'FeO'-Al2O3-TiO2 in contact with metallic iron, at a total pressure below 1 atm, have been determined by the quenching technique. Four invariant points have been located, with phase assemblages and temperatures as follows; wuestite, ulvoespinel, nercynite and liquid, 1306 C; ulvoespinel, ilmenite, ferropseudobrookite and liquid, 1340 C; ulvoespinel, hercynite, ferropseudobrookite and liquid, 1367 C; hercynite, ferropseudobrookite, corundum and liquid, 1465 C. The data obtained confirm the presence of a miscibility gap between titanate and aluminate spinels, and provide quantitative data for the effect of Al2O3 on mutual stability relations among spinel, ilmenite, and ferropseudobrookite phases in the presence of liquid at high temperatures and strongly reducing conditions. It is shown that Al2O3 has a strong stabilizing effect on the phase assemblage ferropseudobrookite and spinel relative to ilmenite.

Successful kidney transplantation across a positive complement-dependent cytotoxicity crossmatch by using C1q assay-directed, bortezomib-assisted desensitization

PubMed Central

Lee, Juhan; Park, Borae G.; Jeong, Hyang Sook; Park, Youn Hee; Kim, Sinyoung; Kim, Beom Seok; Kim, Hye Jin; Huh, Kyu Ha; Jeong, Hyeon Joo; Kim, Yu Seun

2017-01-01

Abstract Rationale: Human leukocyte antigen (HLA) is the major immunologic barrier in kidney transplantation (KT). Various desensitization protocols to overcome the HLA barrier have increased the opportunity for transplantation in sensitized patients. In addition, technological advances in solid-phase assays have permitted more comprehensive assessment of donor-specific antibodies. Although various desensitization therapies and immunologic techniques have been developed, the final transplantation decision is still based on the classic complement-dependent cytotoxicity (CDC) crossmatch (XM) technique. Some patients who fail to achieve negative XM have lost their transplant opportunities, even after receiving sufficient desensitization therapies. Patient concerns: A 57-year-old male with end-stage renal disease secondary to chronic glomerulonephritis was scheduled to have a second transplant from his son, but CDC XM was positive. Diagnoses: Initial CDC XM (Initial T-AHG 1:32) and flow-cytometry XM were positive. Anti-HLA-B59 donor specific antibody was detected by Luminex single antigen assay. Interventions: Herein, we report a successful case of KT across a positive CDC XM (T-AHG 1:8 at the time of transplantation) by using C1q assay-directed, bortezomib-assisted desensitization. After confirming a negative conversion in the C1q donor-specific antibody, we decided to perform KT accepting a positive AHG-CDC XM of 1:8 at the time of transplantation. Outcomes: The posttransplant course was uneventful and a protocol biopsy at 3 months showed no evidence of rejection. The patient had excellent graft function at 12 months posttransplant. Lessons: The results of XM test and solid-phase assay should be interpreted in the context of the individual patient. PMID:28953652

Successful kidney transplantation across a positive complement-dependent cytotoxicity crossmatch by using C1q assay-directed, bortezomib-assisted desensitization: A case report.

PubMed

Lee, Juhan; Park, Borae G; Jeong, Hyang Sook; Park, Youn Hee; Kim, Sinyoung; Kim, Beom Seok; Kim, Hye Jin; Huh, Kyu Ha; Jeong, Hyeon Joo; Kim, Yu Seun

2017-09-01

Human leukocyte antigen (HLA) is the major immunologic barrier in kidney transplantation (KT). Various desensitization protocols to overcome the HLA barrier have increased the opportunity for transplantation in sensitized patients. In addition, technological advances in solid-phase assays have permitted more comprehensive assessment of donor-specific antibodies. Although various desensitization therapies and immunologic techniques have been developed, the final transplantation decision is still based on the classic complement-dependent cytotoxicity (CDC) crossmatch (XM) technique. Some patients who fail to achieve negative XM have lost their transplant opportunities, even after receiving sufficient desensitization therapies. A 57-year-old male with end-stage renal disease secondary to chronic glomerulonephritis was scheduled to have a second transplant from his son, but CDC XM was positive. Initial CDC XM (Initial T-AHG 1:32) and flow-cytometry XM were positive. Anti-HLA-B59 donor specific antibody was detected by Luminex single antigen assay. Herein, we report a successful case of KT across a positive CDC XM (T-AHG 1:8 at the time of transplantation) by using C1q assay-directed, bortezomib-assisted desensitization. After confirming a negative conversion in the C1q donor-specific antibody, we decided to perform KT accepting a positive AHG-CDC XM of 1:8 at the time of transplantation. The posttransplant course was uneventful and a protocol biopsy at 3 months showed no evidence of rejection. The patient had excellent graft function at 12 months posttransplant. The results of XM test and solid-phase assay should be interpreted in the context of the individual patient.

Amperometric detector for gas chromatography based on a silica sol-gel solid electrolyte.

PubMed

Steinecker, William H; Miecznikowski, Krzysztof; Kulesza, Pawel J; Sandlin, Zechariah D; Cox, James A

2017-11-01

An electrochemical cell comprising a silica sol-gel solid electrolyte, a working electrode that protrudes into a gas phase, and reference and counter electrodes that contact the solid electrolyte comprises an amperometric detector for gas chromatography. Under potentiostatic conditions, a current related to the concentration of an analyte in the gas phase is produced by its oxidation at the three-phase boundary among the sol-gel, working electrode, and the gas phase. The sol-gel is processed to contain an electrolyte that also serves as a humidistat to maintain a constant water activity even in the presence the gas chromatographic mobile phase. Response was demonstrated toward a diverse set of analytes, namely hydrogen, 1,2-ethandithiol, phenol, p-cresol, and thioanisole. Using flow injection amperometry of hydrogen with He as the carrier gas, 90% of the steady-state current was achieved in < 1s at a flow rate of 20mLmin -1 . A separation of 1,2-ethandithiol, phenol, p-cresol, and thioanisole at a 2.2mLmin -1 flow rate was achieved with respective detection limits (k = 3 criterion) of 4, 1, 3, and 70 ppmv when the working electrode potential was 800mV. Copyright © 2017 Elsevier B.V. All rights reserved.

Simultaneous determination of the HIV nucleoside analogue reverse transcriptase inhibitors lamivudine, didanosine, stavudine, zidovudine and abacavir in human plasma by reversed phase high performance liquid chromatography.

PubMed

Verweij-van Wissen, C P W G M; Aarnoutse, R E; Burger, D M

2005-02-25

A reversed phase high performance liquid chromatography method was developed for the simultaneous quantitative determination of the nucleoside reverse transcriptase inhibitors (NRTIs) lamivudine, didanosine, stavudine, zidovudine and abacavir in plasma. The method involved solid-phase extraction with Oasis MAX cartridges from plasma, followed by high performance liquid chromatography with a SymmetryShield RP 18 column and ultraviolet detection set at a wavelength of 260 nm. The assay was validated over the concentration range of 0.015-5 mg/l for all five NRTIs. The average accuracies for the assay were 92-102%, inter- and intra-day coefficients of variation (CV) were <2.5% and extraction recoveries were higher than 97%. This method proved to be simple, accurate and precise, and is currently in use in our laboratory for the quantitative analysis of NRTIs in plasma.

Combinatorial Study of Gradient Ag-Al Thin Films: Microstructure, Phase Formation, Mechanical and Electrical Properties.

PubMed

Mao, Fang; Taher, Mamoun; Kryshtal, Oleksandr; Kruk, Adam; Czyrska-Filemonowicz, Aleksandra; Ottosson, Mikael; Andersson, Anna M; Wiklund, Urban; Jansson, Ulf

2016-11-09

A combinatorial approach is applied to rapidly deposit and screen Ag-Al thin films to evaluate the mechanical, tribological, and electrical properties as a function of chemical composition. Ag-Al thin films with large continuous composition gradients (6-60 atom % Al) were deposited by a custom-designed combinatorial magnetron sputtering system. X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning and transmission electron microscopy (SEM and TEM), X-ray photoelectron spectroscopy (XPS), nanoindentation, and four-point electrical resistance screening were employed to characterize the chemical composition, structure, and physical properties of the films in a time-efficient way. For low Al contents (<13 atom %), a highly (111)-textured fcc phase was formed. At higher Al contents, a (002)-textured hcp solid solution phase was formed followed by a fcc phase in the most Al-rich regions. No indication of a μ phase was observed. The Ag-Al films with fcc-Ag matrix is prone to adhesive material transfer leading to a high friction coefficient (>1) and adhesive wear, similar to the behavior of pure Ag. In contrast, the hexagonal solid solution phase (from ca. 15 atom %Al) exhibited dramatically reduced friction coefficients (about 15% of that of the fcc phase) and dramatically reduced adhesive wear when tested against the pure Ag counter surface. The increase in contact resistance of the Ag-Al films is limited to only 50% higher than a pure Ag reference sample at the low friction and low wear region (19-27 atom %). This suggests that a hcp Ag-Al alloy can have a potential use in sliding electrical contact applications and in the future will replace pure Ag in specific electromechanical applications.

Determination of phosphonoformate (foscarnet) in calf and human serum by automated solid-phase extraction and high-performance liquid chromatography with amperometric detection.

PubMed

Ba, B B; Corniot, A G; Ducint, D; Breilh, D; Grellet, J; Saux, M C

1999-03-05

An isocratic high-performance liquid chromatographic method with automated solid-phase extraction has been developed to determine foscarnet in calf and human serums. Extraction was performed with an anion exchanger, SAX, from which the analyte was eluted with a 50 mM potassium pyrophosphate buffer, pH 8.4. The mobile phase consisted of methanol-40 mM disodium hydrogenphosphate, pH 7.6 containing 0.25 mM tetrahexylammonium hydrogensulphate (25:75, v/v). The analyte was separated on a polyether ether ketone (PEEK) column 150x4.6 mm I.D. packed with Kromasil 100 C18, 5 microm. Amperometric detection allowed a quantification limit of 15 microM. The assay was linear from 15 to 240 microM. The recovery of foscarnet from calf serum ranged from 60.65+/-1.89% for 15 microM to 67.45+/-1.24% for 200 microM. The coefficient of variation was < or = 3.73% for intra-assay precision and < or =7.24% for inter-assay precision for calf serum concentrations ranged from 15 to 800 microM. For the same samples, the deviation from the nominal value ranged from -8.97% to +5.40% for same day accuracy and from -4.50% to +2.77% for day-to-day accuracy. Selectivity was satisfactory towards potential co-medications. Replacement of human serum by calf serum for calibration standards and quality control samples was validated. Automation brought more protection against biohazards and increase in productivity for routine monitoring and pharmacokinetic studies.

Analysis of Gibbs monolayer adsorbed at the toluene/water interface by UV-visible partial internal reflection spectrometry.

PubMed

Moriya, Yoshio; Hasegawa, Takeshi; Okada, Tetsuo; Ogawa, Nobuaki; Kawai, Erika; Abe, Kosuke; Ogasawara, Masataka; Kato, Sumio; Nakata, Shinichi

2006-11-15

Gibbs monolayers of lipophilic tetraphenylporphyrinatomanganese(III) and hydrophilic diacid of meso-tetrakis(4-sulfonatopheny)porphyrin adsorbed at the liquid-liquid interface have been analyzed by UV-visible external reflection (ER) and partial internal reflection (PIR) spectra measured at different angles of incidence. The angle-dependent ER and PIR spectra over the Brewster angles (thetaERB and thetaIRB) have readily been measured at the toluene/water interface. As preliminarily expected in our previous study, the present study has first proved that the reflection-absorbance of UV-visible PIR spectra quantitatively agrees with the theoretical calculations for the Gibbs monolayer over thetaIRB. In addition, it has also been proved that the absorbance of the PIR spectra is greatly enhanced in comparison to that of the ATR spectra. The enhancement is caused by an optical effect in the monolayer sandwiched between two phases of toluene and water that have different but refractive indices close to each other. This optical enhancement requires an optically perfect contact between the phases, which is difficult to prepare for a solid-solid contact. At the liquid/liquid interface, however, an ideal optical contact is easily realized, which makes the enhancement as much as the theoretical expectation. The PIR spectrometry will be recognized to be a new high-sensitive analytical tool to study Gibbs monolayer at the liquid/liquid interface.

3,3',5-Triiodo-L-thyronine-like activity in effluents from domestic sewage treatment plants detected by in vitro and in vivo bioassays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murata, Tomonori; Yamauchi, Kiyoshi

2008-02-01

Thyroid system-disrupting activity in effluents from municipal domestic sewage treatment plants was detected using three in vitro assays and one in vivo assay. Contaminants in the effluents were extracted by solid-phase extraction (SPE) and eluted stepwise with different organic solvents. The majority of the thyroid system-disrupting activity was detected in the dichloromethane/methanol (1/1) fraction after SPE in all three in vitro assays: competitive assays of 3,3',5-[{sup 125}I]triiodo-L-thyronine ([{sup 125}I]T{sub 3}) binding to the plasma protein transthyretin (TTR assay) and thyroid hormone receptor (TR assay) and T{sub 3}-dependent luciferase assay (Luc assay). Subsequent reverse-phase high-performance liquid chromatography (RP-HPLC) of the dichloromethane/methanolmore » (1/1) fraction separated contaminants potent in the TR and Luc assays from those potent in the TTR assay. The contaminants potent in the TR and Luc assays were also potent in an in vivo short-term gene expression assay in Xenopus laevis (Tadpole assay). The present study demonstrated that the effluents from domestic sewage treatment plants contain contaminants with T{sub 3}-like activity of {approx} 10{sup -10} M T{sub 3}-equivalent concentration (T{sub 3}EQ) and that the TR and Luc assays are powerful in vitro bioassays for detecting thyroid system-disrupting activity in effluents. The availability and applicability of these bioassays for screening contaminants with thyroid system-disrupting activity in the water environment are discussed.« less

Electrochemical pesticide detection with AutoDip--a portable platform for automation of crude sample analyses.

PubMed

Drechsel, Lisa; Schulz, Martin; von Stetten, Felix; Moldovan, Carmen; Zengerle, Roland; Paust, Nils

2015-02-07

Lab-on-a-chip devices hold promise for automation of complex workflows from sample to answer with minimal consumption of reagents in portable devices. However, complex, inhomogeneous samples as they occur in environmental or food analysis may block microchannels and thus often cause malfunction of the system. Here we present the novel AutoDip platform which is based on the movement of a solid phase through the reagents and sample instead of transporting a sequence of reagents through a fixed solid phase. A ball-pen mechanism operated by an external actuator automates unit operations such as incubation and washing by consecutively dipping the solid phase into the corresponding liquids. The platform is applied to electrochemical detection of organophosphorus pesticides in real food samples using an acetylcholinesterase (AChE) biosensor. Minimal sample preparation and an integrated reagent pre-storage module hold promise for easy handling of the assay. Detection of the pesticide chlorpyrifos-oxon (CPO) spiked into apple samples at concentrations of 10(-7) M has been demonstrated. This concentration is below the maximum residue level for chlorpyrifos in apples defined by the European Commission.

Regional water-quality analysis of 2,4-D and dicamba in river water using gas chromatography-isotope dilution mass spectrometry

USGS Publications Warehouse

Thurman, E.M.; Zimmerman, L.R.; Aga, D.S.; Gilliom, R.J.

2001-01-01

Gas chromatography with isotope dilution mass spectrometry (GC-MS) and enzyme-linked immunosorbent assay (ELISA) were used in regional National Water Quality Assessment studies of the herbicides, 2,4-D and dicamba, in river water across the United States. The GC-MS method involved solid-phase extraction, derivatized with deutemted 2,4-D, and analysis by selected ion monitoring. The ELISA method was applied after preconcentration with solid-phase extraction. The ELISA method was unreliable because of interference from humic substances that were also isolated by solid-phase extraction. Therefore, GC-MS was used to analyzed 80 samples from river water from 14 basins. The frequency of detection of dicamba (28%) was higher than that for 2,4-D (16%). Concentrations were higher for dicamba than for 2,4-D, ranging from less than the detection limit (<0.05 ??g/L) to 3.77 ??g/L, in spite of 5 times more annual use of 2,4-D as compared to dicamba. These results suggest that 2,4-D degrades more rapidly in the environment than dicamba.

Acyl guanidine inhibitors of β-secretase (BACE-1): optimization of a micromolar hit to a nanomolar lead via iterative solid- and solution-phase library synthesis.

PubMed

Gerritz, Samuel W; Zhai, Weixu; Shi, Shuhao; Zhu, Shirong; Toyn, Jeremy H; Meredith, Jere E; Iben, Lawrence G; Burton, Catherine R; Albright, Charles F; Good, Andrew C; Tebben, Andrew J; Muckelbauer, Jodi K; Camac, Daniel M; Metzler, William; Cook, Lynda S; Padmanabha, Ramesh; Lentz, Kimberley A; Sofia, Michael J; Poss, Michael A; Macor, John E; Thompson, Lorin A

2012-11-08

This report describes the discovery and optimization of a BACE-1 inhibitor series containing an unusual acyl guanidine chemotype that was originally synthesized as part of a 6041-membered solid-phase library. The synthesis of multiple follow-up solid- and solution-phase libraries facilitated the optimization of the original micromolar hit into a single-digit nanomolar BACE-1 inhibitor in both radioligand binding and cell-based functional assay formats. The X-ray structure of representative inhibitors bound to BACE-1 revealed a number of key ligand:protein interactions, including a hydrogen bond between the side chain amide of flap residue Gln73 and the acyl guanidine carbonyl group, and a cation-π interaction between Arg235 and the isothiazole 4-methoxyphenyl substituent. Following subcutaneous administration in rats, an acyl guanidine inhibitor with single-digit nanomolar activity in cells afforded good plasma exposures and a dose-dependent reduction in plasma Aβ levels, but poor brain exposure was observed (likely due to Pgp-mediated efflux), and significant reductions in brain Aβ levels were not obtained.

Detection of IgA-class circulating immune complexes (CIC) in sera from patients with IgA nephropathy using a solid-phase anti-C3 Facb enzyme immunoassay (EIA).

PubMed Central

Yagame, M; Tomino, Y; Miura, M; Tanigaki, T; Suga, T; Nomoto, Y; Sakai, H

1987-01-01

The detection of circulating immune complexes (CIC) in sera from patients with IgA nephropathy is described. A solid-phase anti-C3 Facb enzyme immunoassay (EIA) was employed for detection of IgA-, IgG- and IgM-CIC in sera. The C1q-binding enzyme assay was also used for the detection of CIC in sera from these patients and healthy adults. Twenty-two patients with IgA nephropathy, 14 patients with other glomerular diseases and 19 healthy adults were examined by anti-C3 Facb EIA. The levels of IgA-CIC in sera from patients with IgA nephropathy were significantly higher than those in sera from patients with other glomerular diseases and healthy adults. CIC measured by the C1q-binding enzyme assay was detected in some patients with IgA nephropathy. The levels of serum IgA in patients with IgA nephropathy were significantly higher than those in patients with other glomerular diseases and healthy adults. However, there was no significant correlation between the levels of IgA-CIC in sera and those of serum IgA in patients with IgA nephropathy. There was also no significant correlation between the levels of IgA-CIC in sera and the degree of histopathological injuries in the patients. It is concluded that the solid-phase anti-C3 Facb EIA is useful for the detection of IgA-CIC in sera from patients with IgA nephropathy. PMID:3301093

Simultaneous analysis of hydrochlorothiazide, triamterene and reserpine in rat plasma by high performance liquid chromatography and tandem solid-phase extraction.

PubMed

Li, Hang; He, Junting; Liu, Qin; Huo, Zhaohui; Liang, Si; Liang, Yong

2011-03-01

A tandem solid-phase extraction method (SPE) of connecting two different cartridges (C(18) and MCX) in series was developed as the extraction procedure in this article, which provided better extraction yields (>86%) for all analytes and more appropriate sample purification from endogenous interference materials compared with a single cartridge. Analyte separation was achieved on a C(18) reversed-phase column at the wavelength of 265 nm by high-performance liquid chromatography (HPLC). The method was validated in terms of extraction yield, precision and accuracy. These assays gave mean accuracy values higher than 89% with RSD values that were always less than 3.8%. The method has been successfully applied to plasma samples from rats after oral administration of target compounds. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation of Phase Mixing in Amorphous Solid Dispersions of AMG 517 in HPMC-AS Using DSC, Solid-State NMR, and Solution Calorimetry.

PubMed

Calahan, Julie L; Azali, Stephanie C; Munson, Eric J; Nagapudi, Karthik

2015-11-02

Intimate phase mixing between the drug and the polymer is considered a prerequisite to achieve good physical stability for amorphous solid dispersions. In this article, spray dried amorphous dispersions (ASDs) of AMG 517 and HPMC-as were studied by differential scanning calorimetry (DSC), solid-state NMR (SSNMR), and solution calorimetry. DSC analysis showed a weakly asymmetric (ΔTg ≈ 13.5) system with a single glass transition for blends of different compositions indicating phase mixing. The Tg-composition data was modeled using the BKCV equation to accommodate the observed negative deviation from ideality. Proton spin-lattice relaxation times in the laboratory and rotating frames ((1)H T1 and T1ρ), as measured by SSNMR, were consistent with the observation that the components of the dispersion were in intimate contact over a 10-20 nm length scale. Based on the heat of mixing calculated from solution calorimetry and the entropy of mixing calculated from the Flory-Huggins theory, the free energy of mixing was calculated. The free energy of mixing was found to be positive for all ASDs, indicating that the drug and polymer are thermodynamically predisposed to phase separation at 25 °C. This suggests that miscibility measured by DSC and SSNMR is achieved kinetically as the result of intimate mixing between drug and polymer during the spray drying process. This kinetic phase mixing is responsible for the physical stability of the ASD.

Impact of solid second phases on deformation mechanisms of naturally deformed salt rocks (Kuh-e-Namak, Dashti, Iran) and rheological stratification of the Hormuz Salt Formation

NASA Astrophysics Data System (ADS)

Závada, P.; Desbois, G.; Urai, J. L.; Schulmann, K.; Rahmati, M.; Lexa, O.; Wollenberg, U.

2015-05-01

Viscosity contrasts displayed in flow structures of a mountain namakier (Kuh-e-Namak - Dashti), between 'weak' second phase bearing rock salt and 'strong' pure rock salt types are studied for deformation mechanisms using detailed quantitative microstructural study. While the solid inclusions rich ("dirty") rock salts contain disaggregated siltstone and dolomite interlayers, "clean" salts reveal microscopic hematite and remnants of abundant fluid inclusions in non-recrystallized cores of porphyroclasts. Although the flow in both, the recrystallized "dirty" and "clean" salt types is accommodated by combined mechanisms of pressure-solution creep (PS), grain boundary sliding (GBS), transgranular microcracking and dislocation creep accommodated grain boundary migration (GBM), their viscosity contrasts observed in the field outcrops are explained by: 1) enhanced ductility of "dirty" salts due to increased diffusion rates along the solid inclusion-halite contacts than along halite-halite contacts, and 2) slow rates of intergranular diffusion due to dissolved iron and inhibited dislocation creep due to hematite inclusions for "clean" salt types Rheological contrasts inferred by microstructural analysis between both salt rock classes apply in general for the "dirty" salt forming Lower Hormuz and the "clean" salt forming the Upper Hormuz of the Hormuz Formation and imply strain rate gradients or decoupling along horizons of mobilized salt types of different composition and microstructure.

Investigation of Crimean-Congo Hemorrhagic Fever Virus Transmission from Patients to Relatives: A Prospective Contact Tracing Study

PubMed Central

Gozel, Mustafa Gokhan; Bakir, Mehmet; Oztop, Atifet Yasemin; Engin, Aynur; Dokmetas, Ilyas; Elaldi, Nazif

2014-01-01

We investigated the possibility of transmission of Crimean-Congo hemorrhagic fever (CCHF) virus through respiratory and physical contact. In this prospective study, we traced 116 close relatives of confirmed CCHF cases who were in close contact with the patients during the acute phase of the infection and evaluated the type of contact between patients and their relatives. These relatives were followed for clinical signs or symptoms indicative of CCHF disease, blood samples of those with and without clinical signs were analyzed for CCHF virus immunoglobulin M and G (IgM and IgG, respectively) by enzyme-linked immunosorbent assay. No close relatives developed any signs or symptoms of CCHF and were negative for CCHF virus IgM and IgG. The results suggest that CCHF virus is not easily transmitted from person to person through respiratory or physical contact. PMID:24166037

Solid-on-solid contact in a sphere-wall collision in a viscous fluid

NASA Astrophysics Data System (ADS)

Birwa, Sumit Kumar; Rajalakshmi, G.; Govindarajan, Rama; Menon, Narayanan

2018-04-01

We study experimentally the collision between a sphere falling through a viscous fluid and a solid plate below. It is known that there is a well-defined threshold Stokes number above which the sphere rebounds from such a collision. Our experiment tests for direct contact between the colliding bodies and, contrary to prior theoretical predictions, shows that solid-on-solid contact occurs even for Stokes numbers just above the threshold for rebounding. The dissipation is fluid dominated, though details of the contact mechanics depend on the surface and bulk properties of the solids. Our experiments and a model calculation indicate that mechanical contact between the two colliding objects is generic and will occur for any realistic surface roughness.

Simultaneous determination of all-trans and 13-cis retinoic acids and their 4-oxo metabolites by adsorption liquid chromatography after solid-phase extraction.

PubMed

Lefebvre, P; Agadir, A; Cornic, M; Gourmel, B; Hue, B; Dreux, C; Degos, L; Chomienne, C

1995-04-07

All-trans retinoic acid (all-trans RA), the active metabolite of vitamin A, has been demonstrated to be an efficient alternative to chemotherapy in the treatment of acute promyelocytic leukemia (APL), the AML3 subtype of the FAB cytological classification. Complete remission is obtained by inducing terminal granulocytic differentiation of the leukemic cells. To study all-trans RA pharmacokinetics in patients with APL, a rapid, precise and selective high-performance liquid chromatographic (HPLC) assay was developed. This method is easy and shows good repeatability (C.V. = 8.41-12.44%), reproducibility (C.V. = 9.19-14.73%), accuracy (C.V. = 3.5-11%) and sensitivity with a detection limit of 5 pmol/ml. The analysis is performed using normal-phase HPLC in an isocratic mode with UV detection after solid-phase extraction on octadecyl (C18) columns. The mobile phase is hexane-dichloromethane-dioxane (78:18:4, v/v) containing 1% acetic acid.

Calcium-selective electrodes based on photo-cured polyurethane-acrylate membranes covalently attached to methacrylate functionalized poly(3,4-ethylenedioxythiophene) as solid-contact.

PubMed

Ocaña, Cristina; Abramova, Natalia; Bratov, Andrey; Lindfors, Tom; Bobacka, Johan

2018-08-15

We report here the fabrication of solid-contact calcium-selective electrodes (Ca 2+ -SCISEs) made of a polyurethane acrylate ion-selective membrane (ISM) that was covalently attached to the underlying ion-to-electron transducer (solid-contact). Methacrylate-functionalized poly(3,4-ethylenedioxythiophene) (Meth-PEDOT) and Meth-PEDOT films containing either multiwalled carbon nanotubes (MWCNT) or carboxylated MWCNT (cMWCNT) were used as solid contacts. The solid contacts were deposited by drop-casting on screen-printed electrodes and characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and potentiometry. Covalent binding between the solid contact and the ISM was obtained via photopolymerization in order to increase the robustness of the Ca 2+ -SCISEs. The performance of the Ca 2+ -SCISEs was studied by measuring their potentiometric response and their sensitivity to light, oxygen and carbon dioxide. Meth-PEDOT was found to be a promising solid-contact material to develop low-cost and easy to prepare ISEs. Copyright © 2018 Elsevier B.V. All rights reserved.

Multiplexed interfacial transduction of nucleic acid hybridization using a single color of immobilized quantum dot donor and two acceptors in fluorescence resonance energy transfer.

PubMed

Algar, W Russ; Krull, Ulrich J

2010-01-01

A multiplexed solid-phase assay for the detection of nucleic acid hybridization was developed on the basis of a single color of immobilized CdSe/ZnS quantum dot (QD) as a donor in fluorescence resonance energy transfer (FRET). This work demonstrated that two channels of detection did not necessitate two different QD donors. Two probe oligonucleotides were coimmobilized on optical fibers modified with QDs, and a sandwich assay was used to associate the acceptor dyes with interfacial hybridization events without target labeling. FRET-sensitized acceptor emission provided an analytical signal that was concentration dependent down to 10 nM. Changes in the ratio of coimmobilized probe oligonucleotides were found to yield linear changes in the relative amounts of acceptor emission. These changes were compared to previous studies that used mixed films of two QD donors for two detection channels. The analysis indicated that probe dilution effects were primarily driven by changes in acceptor number density and that QD dilution effects or changes in mean donor-acceptor distance were secondary. Hybridization kinetics were found to be consistent between different ratios of coimmobilized probes, suggesting that hybridization in this type of system occurred via the accepted model for solid-phase hybridization, where adsorption and then diffusion at the solid interface drove hybridization.

Line tension effects on the wetting of nanostructures: an energy method

NASA Astrophysics Data System (ADS)

Guo, Hao-Yuan; Li, Bo; Feng, Xi-Qiao

2017-09-01

The superhydrophobicity and self-cleaning property of micro/nano-structured solid surfaces require a stable Cassie-Baxter (CB) wetting state at the liquid-solid interface. We present an energy method to investigate how the three-phase line tension affects the CB wetting state on nanostructured materials. For some nanostructures, the line tension may engender a distinct energy barrier, which restricts the position of the three-phase contact line and affects the stability of the CB wetting state. We ascertain the upper and lower limits of the critical pressure at the CB-Wenzel transition. Our results suggest that superhydrophobicity on nanostructures can be modulated by tailoring the line tension and harnessing the curvature effect. This study also provides new insights into the sinking phenomena observed in the nanoparticle-floating experiment.

Porous protective solid phase micro-extractor sheath

DOEpatents

Andresen, Brian D.; Randich, Erik

2005-03-29

A porous protective sheath for active extraction media used in solid phase microextraction (SPME). The sheath permits exposure of the media to the environment without the necessity of extending a fragile coated fiber from a protective tube or needle. Subsequently, the sheath can pierce and seal with GC-MS septums, allowing direct injection of samples into inlet ports of analytical equipment. Use of the porous protective sheath, within which the active extraction media is contained, mitigates the problems of: 1) fiber breakage while the fiber is extended during sampling, 2) active media coating loss caused by physical contact of the bare fiber with the sampling environment; and 3) coating slough-off during fiber extension and retraction operations caused by rubbing action between the fiber and protective needle or tube.

Thermodynamics of Surface Nanobubbles.

PubMed

Zargarzadeh, Leila; Elliott, Janet A W

2016-11-01

In this paper, we examine the thermodynamic stability of surface nanobubbles. The appropriate free energy is defined for the system of nanobubbles on a solid surface submerged in a supersaturated liquid solution at constant pressure and temperature, under conditions where an individual nanobubble is not in diffusive contact with a gas phase outside of the system or with other nanobubbles on the time scale of the experiment. The conditions under which plots of free energy versus the radius of curvature of the nanobubbles show a global minimum, which denotes the stable equilibrium state, are explored. Our investigation shows that supersaturation and an anomalously high contact angle (measured through the liquid) are required to have stable surface nanobubbles. In addition, the anomalously high contact angle of surface nanobubbles is discussed from the standpoint of a framework recently proposed by Koch, Amirfazli, and Elliott that relates advancing and receding contact angles to thermodynamic equilibrium contact angles, combined with the existence of a gas enrichment layer.

Stability of Contact Lines in Fluids: 2D Stokes Flow

NASA Astrophysics Data System (ADS)

Guo, Yan; Tice, Ian

2018-02-01

In an effort to study the stability of contact lines in fluids, we consider the dynamics of an incompressible viscous Stokes fluid evolving in a two-dimensional open-top vessel under the influence of gravity. This is a free boundary problem: the interface between the fluid in the vessel and the air above (modeled by a trivial fluid) is free to move and experiences capillary forces. The three-phase interface where the fluid, air, and solid vessel wall meet is known as a contact point, and the angle formed between the free interface and the vessel is called the contact angle. We consider a model of this problem that allows for fully dynamic contact points and angles. We develop a scheme of a priori estimates for the model, which then allow us to show that for initial data sufficiently close to equilibrium, the model admits global solutions that decay to equilibrium exponentially quickly.

Sensitive method for the quantitative determination of bromocriptine in human plasma by liquid chromatography-tandem mass spectrometry.

PubMed

Salvador, Arnaud; Dubreuil, Didier; Denouel, Jannick; Millerioux, L

2005-06-25

A sensitive LC-MS-MS assay for the quantitative determination of bromocriptine has been developed and validated and is described in this work. The assay involved the extraction of the analyte from 1 ml of human plasma using a solid phase extraction on Oasis MCX cartridges. Chromatography was performed on a Symmetry C18 (2.1 mm x 100 mm, 3.5 microm) column using a mobile phase consisting of 25:75:01 acetonitrile-water-formic acid with a flow rate of 250 microl/min. The linearity was within the concentration range of 2-500 pg/ml. The lower limit of quantification was 2 pg/ml. This method has been demonstrated to be an improvement over existing methods due to its greater sensitivity and specificity.

Liquid phase sintered compacts in space

NASA Technical Reports Server (NTRS)

Mookherji, T. K.; Mcanelly, W. B.

1974-01-01

A model that will explain the effect of gravity on liquid phase sintering was developed. Wetting characteristics and density segregation which are the two important phenomena in liquid phase sintering are considered in the model development. Experiments were conducted on some selected material combinations to study the gravity effects on liquid phase sintering, and to verify the validity of the model. It is concluded that: (1) The surface tension forces acting on solid particles in a one-g environment are not appreciably different from those anticipated in a 0.00001g/g sub 0 (or lower) environment. (2) The capillary forces are dependent on the contact angle, the quantity of the liquid phase, and the distance between solid particles. (3) The pores (i.e., bubbles) do not appear to be driven to the surface by gravity-produced buoyancy forces. (4) The length of time to produce the same degree of settling in a low-gravity environment will be increased significantly. (5) A low gravity environment would appear to offer a unique means of satisfactorily infiltrating a larger and/or complex shaped compact.

A stable perovskite electrolyte in moist air for Li-ion batteries.

PubMed

Li, Yutao; Xu, Henghui; Chien, Po-Hsiu; Wu, Nan; Xin, Sen; Xue, Leigang; Park, Kyusung; Hu, Yan-Yan; Goodenough, John B

2018-05-07

Solid-oxide Li+ electrolytes of a rechargeable cell are generally sensitive to moisture in the air, H+ exchanges for the mobile Li+ of the electrolyte and forms insulating surface phases at the electrolyte interfaces and in the grain boundaries of a polycrystalline membrane. These surface phases dominate the total interfacial resistance of a conventional rechargeable cell having a solid-electrolyte separator. We report a new perovskite Li+ solid electrolyte, Li0.38Sr0.44Ta0.7Hf0.3O2.95F0.05, having a Li-ion conductivity σLi = 4.8×10-4 S cm-1 at 25 oC that does not react with water having 3≤pH≤14. The solid electrolyte with a thin Li+-conducting polymer on its surface to prevent reduction of Ta5+ is wet by metallic lithium and provides low-impedance dendrite-free plating/stripping of a lithium anode. It is also stable on contact with a composite polymer cathode. With this solid electrolyte, we demonstrate excellent cycling performance of an all-solid-state Li/LiFePO4 cell, a Li-S cell with a polymer-gel cathode, and a supercapacitor. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Detection of antibodies to proteases used in laundry detergents by the radioallergosorbent test.

PubMed

Dor, P J; Agarwal, M K; Gleich, M C; Welsh, P W; Dunnette, S L; Adolphson, C R; Gleich, G J

1986-11-01

Two proteases, Esperase and Alcalase, derived from Bacillus licheniformis and B. subtilis, respectively, are used in laundry products. In testing for the prevalence of IgE antibodies to these enzymes in sera among 300 laundry product workers, we experienced two problems in the establishment of a reliable RAST for these antigens. The first problem was the propensity of the allergen, Esperase, to undergo autolysis, suggesting that solid-phase Esperase might also lose reactivity through degradation. Treatment of Esperase with phenylmethylsulfonyl fluoride stabilized the enzyme and permitted the synthesis of a stable solid-phase antigen. The second problem was the finding that sera reactive with Esperase in the RAST were also reactive with Savinase, an enzyme from B. licheniformis to which the workers were not exposed. Immunochemical analyses of the three enzymes with specific rabbit antisera by gel diffusion and by two-site immunoradiometric assay demonstrated that they were not cross contaminated to any appreciable extent. RAST inhibition demonstrated that solid-phase Esperase possessed unique allergenic determinants in that the reactivity of IgE antibodies was inhibited by low concentrations of Esperase and only by very high concentrations of Alcalase and Savinase. In contrast, the reactivity of solid-phase Alcalase was occasionally inhibited equally well by Esperase and Alcalase. Most strikingly, the reaction of IgE antibodies with solid-phase Savinase was always inhibited by comparable quantities of Esperase, Alcalase, and Savinase. Thus, the establishment of the RAST for these proteases appears to require the use of phenylmethylsulfonyl fluoride to retard autolysis, and the results must be interpreted with caution because IgE antibodies in certain sera demonstrate cross-reactivity with Alcalase and Savinase.

Development of a bioreactor system for the decolorization of dyes by Coriolus versicolor f. antarcticus.

PubMed

Diorio, L A; Mercuri, A A; Nahabedian, D E; Forchiassin, F

2008-05-01

Decolorization of 100 microM malachite green (MG) by Coriolus versicolor f. antarcticus using a two-phase bioreactor, was investigated. In the first phase the decolorization ability of this fungus, growing under conditions of solid-state fermentation (SSF), was proved; in the second phase the capacity of the enzymes present in extracts from the solid residues was exploited. During the first phase using the same culture in the bioreactor, five consecutive charges were made, each with 75 ml of 100 microM MG solution, at 28 degrees C. Each cycle ended when MG solution reached a decolorization of 50%, at this time the bioreactor was discharged to a stainless steel coil at 50 degrees C, initiating the second phase of decolorization. Time required in order to reach 50% decolorization during the first phase varied between 25 and 65 min, with an average retention time of 48 min. The second stage had a retention time of 120 min. Residual MG after this phase varied from 0% to 6.3%. The role of laccase and Mn-peroxidase in MG decolorization is discussed. Toxicity of MG solutions before and after decolorization treatments was assayed using Lumbriculus variegatus as test organism.

Nanoscaled Na3PS4 Solid Electrolyte for All-Solid-State FeS2/Na Batteries with Ultrahigh Initial Coulombic Efficiency of 95% and Excellent Cyclic Performances.

PubMed

Wan, Hongli; Mwizerwa, Jean Pierre; Qi, Xingguo; Xu, Xiaoxiong; Li, Hong; Zhang, Qiang; Cai, Liangting; Hu, Yong-Sheng; Yao, Xiayin

2018-04-18

Nanosized Na 3 PS 4 solid electrolyte with an ionic conductivity of 8.44 × 10 -5 S cm -1 at room temperature is synthesized by a liquid-phase reaction. The resultant all-solid-state FeS 2 /Na 3 PS 4 /Na batteries show an extraordinary high initial Coulombic efficiency of 95% and demonstrate high energy density of 611 Wh kg -1 at current density of 20 mA g -1 at room temperature. The outstanding performances of the battery can be ascribed to good interface compatibility and intimate solid-solid contact at FeS 2 electrode/nanosized Na 3 PS 4 solid electrolytes interface. Meanwhile, excellent cycling stability is achieved for the battery after cycling at 60 mA g -1 for 100 cycles, showing a high capacity of 287 mAh g -1 with the capacity retention of 80%.

Axisymmetric Lattice Boltzmann Model of Droplet Impact on Solid Surfaces

NASA Astrophysics Data System (ADS)

Dalgamoni, Hussein; Yong, Xin

2017-11-01

Droplet impact is a ubiquitous fluid phenomena encountered in scientific and engineering applications such as ink-jet printing, coating, electronics manufacturing, and many others. It is of great technological importance to understand the detailed dynamics of drop impact on various surfaces. The lattice Boltzmann method (LBM) emerges as an efficient method for modeling complex fluid systems involving rapidly evolving fluid-fluid and fluid-solid interfaces with complex geometries. In this work, we model droplet impact on flat solid substrates with well-defined wetting behavior using a two-phase axisymmetric LBM with high density and viscosity contrasts. We extend the two-dimensional Lee and Liu model to capture axisymmetric effect in the normal impact. First we compare the 2D axisymmetric results with the 2D and 3D results reported by Lee and Liu to probe the effect of axisymmetric terms. Then, we explore the effects of Weber number, Ohnesorge number, and droplet-surface equilibrium contact angle on the impact. The dynamic contact angle and spreading factor of the droplet during impact are investigated to qualitatively characterize the impact dynamics.

Atomically thin gallium layers from solid-melt exfoliation

PubMed Central

Kochat, Vidya; Samanta, Atanu; Zhang, Yuan; Bhowmick, Sanjit; Manimunda, Praveena; Asif, Syed Asif S.; Stender, Anthony S.; Vajtai, Robert; Singh, Abhishek K.; Tiwary, Chandra S.; Ajayan, Pulickel M.

2018-01-01

Among the large number of promising two-dimensional (2D) atomic layer crystals, true metallic layers are rare. Using combined theoretical and experimental approaches, we report on the stability and successful exfoliation of atomically thin “gallenene” sheets on a silicon substrate, which has two distinct atomic arrangements along crystallographic twin directions of the parent α-gallium. With a weak interface between solid and molten phases of gallium, a solid-melt interface exfoliation technique is developed to extract these layers. Phonon dispersion calculations show that gallenene can be stabilized with bulk gallium lattice parameters. The electronic band structure of gallenene shows a combination of partially filled Dirac cone and the nonlinear dispersive band near the Fermi level, suggesting that gallenene should behave as a metallic layer. Furthermore, it is observed that the strong interaction of gallenene with other 2D semiconductors induces semiconducting to metallic phase transitions in the latter, paving the way for using gallenene as promising metallic contacts in 2D devices. PMID:29536039

Understanding the Impact of Water on the Miscibility and Microstructure of Amorphous Solid Dispersions: An AFM-LCR and TEM-EDX Study.

PubMed

Li, Na; Gilpin, Christopher J; Taylor, Lynne S

2017-05-01

Miscibility is critical for amorphous solid dispersions (ASDs). Phase-separated ASDs are more prone to crystallization, and thus can lose their solubility advantage leading to product failure. Additionally, dissolution performance can be diminished as a result of phase separation in the ASD matrix. Water is known to induce phase separation during storage for some ASDs. However, the impact of water introduced during preparation has not been as thoroughly investigated to date. The purpose of this study was to develop a mechanistic understanding of the effect of water on the phase behavior and microstructure of ASDs. Evacetrapib and two polymers were selected as the model system. Atomic force microscopy coupled with Lorentz contact resonance, and transmission electron microscopy with energy dispersive X-ray spectroscopy were employed to evaluate the microstructure and composition of phase-separated ASDs. It was found that phase separation could be induced via two routes: solution-state phase separation during ASD formation caused by water absorption during film formation by a hydrophilic solvent, or solid-phase separation following exposure to high RH during storage. Water contents of as low as 2% in the organic solvent system used to dissolve the drug and polymer were found to result in phase separation in the resultant ASD film. These findings have profound implications on lab-scale ASD preparation and potentially also for industrial production. Additionally, these high-resolution imaging techniques combined with orthogonal analyses are powerful tools to visualize structural changes in ASDs, which in turn will enable better links to be made between ASD structure and performance.

Synthesis of Thermogelling Poly(N-isopropylacrylamide)-graft-chondroitin Sulfate Composites with Alginate Microparticles for Tissue Engineering

PubMed Central

Christiani, Thomas R.; Toomer, Katelynn; Sheehan, Joseph; Nitzl, Angelika; Branda, Amanda; England, Elizabeth; Graney, Pamela; Iftode, Cristina; Vernengo, Andrea J.

2016-01-01

Injectable biomaterials are defined as implantable materials that can be introduced into the body as a liquid and solidify in situ. Such materials offer the clinical advantages of being implanted minimally invasively and easily forming space-filling solids in irregularly shaped defects. Injectable biomaterials have been widely investigated as scaffolds for tissue engineering. However, for the repair of certain load-bearing areas in the body, such as the intervertebral disc, scaffolds should possess adhesive properties. This will minimize the risk of dislocation during motion and ensure intimate contact with the surrounding tissue, providing adequate transmission of forces. Here, we describe the preparation and characterization of a scaffold composed of thermally sensitive poly(N-isopropylacrylamide)-graft-chondroitin sulfate (PNIPAAM-g-CS) and alginate microparticles. The PNIPAAm-g-CS copolymer forms a viscous solution in water at RT, into which alginate particles are suspended to enhance adhesion. Above the lower critical solution temperature (LCST), around 30 °C, the copolymer forms a solid gel around the microparticles. We have adapted standard biomaterials characterization procedures to take into account the reversible phase transition of PNIPAAm-g-CS. Results indicate that the incorporation of 50 or 75 mg/ml alginate particles into 5% (w/v) PNIPAAm-g-CS solutions quadruple the adhesive tensile strength of PNIPAAm-gCS alone (p<0.05). The incorporation of alginate microparticles also significantly increases swelling capacity of PNIPAAm-g-CS (p<0.05), helping to maintain a space-filling gel within tissue defects. Finally, results of the in vitro toxicology assay kit, 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) and Live/Dead viability assay indicate that the adhesive is capable of supporting the survival and proliferation of encapsulated Human Embryonic Kidney (HEK) 293 cells over 5 days. PMID:27805604

Contact angle and local wetting at contact line.

PubMed

Li, Ri; Shan, Yanguang

2012-11-06

This theoretical study was motivated by recent experiments and theoretical work that had suggested the dependence of the static contact angle on the local wetting at the triple-phase contact line. We revisit this topic because the static contact angle as a local wetting parameter is still not widely understood and clearly known. To further clarify the relationship of the static contact angle with wetting, two approaches are applied to derive a general equation for the static contact angle of a droplet on a composite surface composed of heterogeneous components. A global approach based on the free surface energy of a thermodynamic system containing the droplet and solid surface shows the static contact angle as a function of local surface chemistry and local wetting state at the contact line. A local approach, in which only local forces acting on the contact line are considered, results in the same equation. The fact that the local approach agrees with the global approach further demonstrates the static contact angle as a local wetting parameter. Additionally, the study also suggests that the wetting described by the Wenzel and Cassie equations is also the local wetting of the contact line rather than the global wetting of the droplet.

Hepatitis E Seroprevalence in Europe: A Meta-Analysis

PubMed Central

Hartl, Johannes; Otto, Benjamin; Madden, Richie Guy; Webb, Glynn; Woolson, Kathy Louise; Kriston, Levente; Vettorazzi, Eik; Lohse, Ansgar W.; Dalton, Harry Richard; Pischke, Sven

2016-01-01

There have been large numbers of studies on anti-HEV IgG seroprevalence in Europe, however, the results of these studies have produced high variability of seroprevalence rates, making interpretation increasingly problematic. Therefore, the aim of this study was to develop a clearer understanding of anti-HEV IgG seroprevalence in Europe and identify risk groups for HEV exposure by a meta-analysis of published studies. Methods: All European HEV-seroprevalence studies from 2003 to 2015 were reviewed. Data were stratified by assay, geographical location, and patient cohort (general population, patients with HIV, solid-organ transplant recipients, chronic liver disease patients, and individuals in contact with swine/wild animals). Data were pooled using a mixed-effects model. Results: Four hundred thirty-two studies were initially identified, of which 73 studies were included in the analysis. Seroprevalence estimates ranged from 0.6% to 52.5%, increased with age, but were unrelated to gender. General population seroprevalence varied depending on assays: Wantai (WT): 17%, Mikrogen (MG): 10%, MP-diagnostics (MP): 7%, DiaPro: 4%, Abbott 2%. The WT assay reported significantly higher seroprevalence rates across all cohorts (p < 0.001). Individuals in contact with swine/wild animals had significantly higher seroprevalence rates than the general population, irrespective of assay (p < 0.0001). There was no difference between any other cohorts. The highest seroprevalence was observed in France (WT: 32%, MP: 16%) the lowest in Italy (WT: 7.5%, MP 0.9%). Seroprevalence varied between and within countries. The observed heterogeneity was attributed to geographical region (23%), assay employed (23%) and study cohort (7%). Conclusion: Seroprevalcence rates primarily depend on the seroassy that is used, followed by the geographical region and study cohort. Seroprevalence is higher in individuals exposed to swine and/or wild animals, and increases with age. PMID:27509518

Hepatitis E Seroprevalence in Europe: A Meta-Analysis.

PubMed

Hartl, Johannes; Otto, Benjamin; Madden, Richie Guy; Webb, Glynn; Woolson, Kathy Louise; Kriston, Levente; Vettorazzi, Eik; Lohse, Ansgar W; Dalton, Harry Richard; Pischke, Sven

2016-08-06

There have been large numbers of studies on anti-HEV IgG seroprevalence in Europe, however, the results of these studies have produced high variability of seroprevalence rates, making interpretation increasingly problematic. Therefore, the aim of this study was to develop a clearer understanding of anti-HEV IgG seroprevalence in Europe and identify risk groups for HEV exposure by a meta-analysis of published studies. All European HEV-seroprevalence studies from 2003 to 2015 were reviewed. Data were stratified by assay, geographical location, and patient cohort (general population, patients with HIV, solid-organ transplant recipients, chronic liver disease patients, and individuals in contact with swine/wild animals). Data were pooled using a mixed-effects model. Four hundred thirty-two studies were initially identified, of which 73 studies were included in the analysis. Seroprevalence estimates ranged from 0.6% to 52.5%, increased with age, but were unrelated to gender. General population seroprevalence varied depending on assays: Wantai (WT): 17%, Mikrogen (MG): 10%, MP-diagnostics (MP): 7%, DiaPro: 4%, Abbott 2%. The WT assay reported significantly higher seroprevalence rates across all cohorts (p < 0.001). Individuals in contact with swine/wild animals had significantly higher seroprevalence rates than the general population, irrespective of assay (p < 0.0001). There was no difference between any other cohorts. The highest seroprevalence was observed in France (WT: 32%, MP: 16%) the lowest in Italy (WT: 7.5%, MP 0.9%). Seroprevalence varied between and within countries. The observed heterogeneity was attributed to geographical region (23%), assay employed (23%) and study cohort (7%). Seroprevalcence rates primarily depend on the seroassy that is used, followed by the geographical region and study cohort. Seroprevalence is higher in individuals exposed to swine and/or wild animals, and increases with age.

Formation of target-specific binding sites in enzymes: solid-phase molecular imprinting of HRP

NASA Astrophysics Data System (ADS)

Czulak, J.; Guerreiro, A.; Metran, K.; Canfarotta, F.; Goddard, A.; Cowan, R. H.; Trochimczuk, A. W.; Piletsky, S.

2016-05-01

Here we introduce a new concept for synthesising molecularly imprinted nanoparticles by using proteins as macro-functional monomers. For a proof-of-concept, a model enzyme (HRP) was cross-linked using glutaraldehyde in the presence of glass beads (solid-phase) bearing immobilized templates such as vancomycin and ampicillin. The cross-linking process links together proteins and protein chains, which in the presence of templates leads to the formation of permanent target-specific recognition sites without adverse effects on the enzymatic activity. Unlike complex protein engineering approaches commonly employed to generate affinity proteins, the method proposed can be used to produce protein-based ligands in a short time period using native protein molecules. These affinity materials are potentially useful tools especially for assays since they combine the catalytic properties of enzymes (for signaling) and molecular recognition properties of antibodies. We demonstrate this concept in an ELISA-format assay where HRP imprinted with vancomycin and ampicillin replaced traditional enzyme-antibody conjugates for selective detection of templates at micromolar concentrations. This approach can potentially provide a fast alternative to raising antibodies for targets that do not require high assay sensitivities; it can also find uses as a biochemical research tool, as a possible replacement for immunoperoxidase-conjugates.Here we introduce a new concept for synthesising molecularly imprinted nanoparticles by using proteins as macro-functional monomers. For a proof-of-concept, a model enzyme (HRP) was cross-linked using glutaraldehyde in the presence of glass beads (solid-phase) bearing immobilized templates such as vancomycin and ampicillin. The cross-linking process links together proteins and protein chains, which in the presence of templates leads to the formation of permanent target-specific recognition sites without adverse effects on the enzymatic activity. Unlike complex protein engineering approaches commonly employed to generate affinity proteins, the method proposed can be used to produce protein-based ligands in a short time period using native protein molecules. These affinity materials are potentially useful tools especially for assays since they combine the catalytic properties of enzymes (for signaling) and molecular recognition properties of antibodies. We demonstrate this concept in an ELISA-format assay where HRP imprinted with vancomycin and ampicillin replaced traditional enzyme-antibody conjugates for selective detection of templates at micromolar concentrations. This approach can potentially provide a fast alternative to raising antibodies for targets that do not require high assay sensitivities; it can also find uses as a biochemical research tool, as a possible replacement for immunoperoxidase-conjugates. Electronic supplementary information (ESI) available: Additional circular dichroism data and nanoparticle tracking analysis trace. See DOI: 10.1039/c6nr02009g

In Situ Local Contact Angle Measurement in a CO2-Brine-Sand System Using Microfocused X-ray CT.

PubMed

Lv, Pengfei; Liu, Yu; Wang, Zhe; Liu, Shuyang; Jiang, Lanlan; Chen, Junlin; Song, Yongchen

2017-04-11

The wettability of porous media is of major interest in a broad range of natural and engineering applications. The wettability of a fluid on a solid surface is usually evaluated by the contact angle between them. While in situ local contact angle measurements are complicated by the topology of porous media, which can make it difficult to use traditional methods, recent advances in microfocused X-ray computed tomography (micro-CT) and image processing techniques have made it possible to measure contact angles on the scale of the pore sizes in such media. However, the effects of ionic strength, CO 2 phase, and flow pattern (drainage or imbibition) on pore-scale contact angle distribution are still not clear and have not been reported in detail in previous studies. In this study, we employed a micro-CT scanner for in situ investigation of local contact angles in a CO 2 -brine-sand system under various conditions. The effects of ionic strength, CO 2 phase, and flow pattern on the local contact-angle distribution were examined in detail. The results showed that the local contact angles vary over a wide range as a result of the interaction of surface contaminants, roughness, pore topology, and capillarity. The wettability of a porous surface could thus slowly weaken with increasing ionic strength, and the average contact angle could significantly increase when gaseous CO 2 (gCO 2 ) turns into supercritical CO 2 (scCO 2 ). Contact angle hysteresis also occurred between drainage and imbibition procedures, and the hysteresis was more significant under gCO 2 condition.

Comparison between solid phase microextraction (SPME) and hollow fiber liquid phase microextraction (HFLPME) for determination of extractables from post-consumer recycled PET into food simulants.

PubMed

Oliveira, Éder Costa; Echegoyen, Yolanda; Cruz, Sandra Andrea; Nerin, Cristina

2014-09-01

Hollow fiber liquid phase microextraction (HFLPME) and solid phase microextraction (SPME) methods for pre-concentration of contaminants (toluene, benzophenone, tetracosane and chloroform) in food simulants were investigated. For HFLPME 1-heptanol, 2-octanone and dibutyl-ether were studied as extracting solvents. Analysis by gas chromatography coupled to mass spectrometry (GC-MS), flame ionization (GC-FID) and electron capture detectors (GC-ECD) were carried out. In addition, the methods were employed to evaluate the safety in use of a PET material after the recycling process (comprising washing, extrusion and solid state polymerization (SSP)) through extractability studies of the contaminants using 10% (v/v) ethanol in deionized water and 3% (w/v) acetic acid in deionized water as food simulants in different conditions: 10 days at 40°C and 2h at 70°C. The HFLPME preconcentration method provided increased sensitivity when compared to the SPME method and allowed to analyze concentration levels below 10 µg surrogate per kg food simulant. The results of the extractability studies showed considerable reductions after the extrusion and SSP processes and indicated the compliance with regulations for using recycled PET in contact with food. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of stress nonhomogeneity on the shear melting of a thin boundary lubrication layer.

PubMed

Lyashenko, Iakov A; Filippov, Alexander E; Popov, Mikhail; Popov, Valentin L

2016-11-01

We consider the dynamical properties of boundary lubrication in contact between two atomically smooth solid surfaces separated by an ultrathin layer of lubricant. In contrast to previous works on this topic, we explicitly consider the heterogeneity of tangential stresses, which arises in a contact of elastic bodies that are moved tangentially relative to each other. To describe phase transitions between structural states of the lubricant we use an approach based on the field theory of phase transitions. It is assumed that the lubricant layer, when stressed, can undergo a shear-melting transition of first or second order. While solutions for the homogeneous system can be easily obtained analytically, the kinetics of the phase transitions in the spatially heterogeneous system can only be studied numerically. In our numerical experiments melting of the lubricant layer starts from the outer boundary of contact and propagates to its center. The melting wave is followed by a wave of solidification. This process repeats itself periodically, following the stick-slip pattern that is characteristic of such systems. Depending on the thermodynamic and kinetic parameters of the model, different modes of sliding with almost complete or only partial intermediate solidification are possible.

Contact efflorescence as a pathway for crystallization of atmospherically relevant particles

PubMed Central

Davis, Ryan D.; Lance, Sara; Gordon, Joshua A.; Ushijima, Shuichi B.; Tolbert, Margaret A.

2015-01-01

Inadequate knowledge of the phase state of atmospheric particles represents a source of uncertainty in global climate and air quality models. Hygroscopic aqueous inorganic particles are often assumed to remain liquid throughout their atmospheric lifetime or only (re)crystallize at low relative humidity (RH) due to the kinetic limitations of efflorescence (salt crystal nucleation and growth from an aqueous solution). Here we present experimental observations of a previously unexplored heterogeneous nucleation pathway that we have termed “contact efflorescence,” which describes efflorescence initiated by an externally located solid particle coming into contact with the surface of a metastable aqueous microdroplet. This study demonstrates that upon a single collision, contact efflorescence is a pathway for crystallization of atmospherically relevant aqueous particles at high ambient RH (≤80%). Soluble inorganic crystalline particles were used as contact nuclei to induce efflorescence of aqueous ammonium sulfate [(NH4)2SO4], sodium chloride (NaCl), and ammonium nitrate (NH4NO3), with efflorescence being observed in several cases close to their deliquescence RH values (80%, 75%, and 62%, respectively). To our knowledge, these observations represent the highest reported efflorescence RH values for microdroplets of these salts. These results are particularly important for considering the phase state of NH4NO3, where the contact efflorescence RH (∼20–60%) is in stark contrast to the observation that NH4NO3 microdroplets do not homogeneously effloresce, even when exposed to extremely arid conditions (<1% RH). Considering the occurrence of particle collisions in the atmosphere (i.e., coagulation), these observations of contact efflorescence challenge many assumptions made about the phase state of inorganic aerosol. PMID:26668396

Contact efflorescence as a pathway for crystallization of atmospherically relevant particles.

PubMed

Davis, Ryan D; Lance, Sara; Gordon, Joshua A; Ushijima, Shuichi B; Tolbert, Margaret A

2015-12-29

Inadequate knowledge of the phase state of atmospheric particles represents a source of uncertainty in global climate and air quality models. Hygroscopic aqueous inorganic particles are often assumed to remain liquid throughout their atmospheric lifetime or only (re)crystallize at low relative humidity (RH) due to the kinetic limitations of efflorescence (salt crystal nucleation and growth from an aqueous solution). Here we present experimental observations of a previously unexplored heterogeneous nucleation pathway that we have termed "contact efflorescence," which describes efflorescence initiated by an externally located solid particle coming into contact with the surface of a metastable aqueous microdroplet. This study demonstrates that upon a single collision, contact efflorescence is a pathway for crystallization of atmospherically relevant aqueous particles at high ambient RH (≤80%). Soluble inorganic crystalline particles were used as contact nuclei to induce efflorescence of aqueous ammonium sulfate [(NH4)2SO4], sodium chloride (NaCl), and ammonium nitrate (NH4NO3), with efflorescence being observed in several cases close to their deliquescence RH values (80%, 75%, and 62%, respectively). To our knowledge, these observations represent the highest reported efflorescence RH values for microdroplets of these salts. These results are particularly important for considering the phase state of NH4NO3, where the contact efflorescence RH (∼20-60%) is in stark contrast to the observation that NH4NO3 microdroplets do not homogeneously effloresce, even when exposed to extremely arid conditions (<1% RH). Considering the occurrence of particle collisions in the atmosphere (i.e., coagulation), these observations of contact efflorescence challenge many assumptions made about the phase state of inorganic aerosol.

76 FR 2388 - National Toxicology Program (NTP); NTP Interagency Center for the Evaluation of Alternative...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-13

... Nonradioactive Versions of the Murine Local Lymph Node Assay (LLNA) for Assessing Allergic Contact Dermatitis... Assay: BrdU-ELISA, A Nonradioactive Alternative Test Method to Assess the Allergic Contact Dermatitis... Lymph Node Assay: DA, A Nonradioactive Alternative Test Method to Assess the Allergic Contact Dermatitis...

Process for depositing I-125 onto a substrate used to manufacture I-125 sources

DOEpatents

McGovern, James J.; Olynyk, Joseph M.

1988-01-01

The invention relates to a process for depositing I-125 on a substrate which comprises contacting a predetermined surface area of substrate with Xe-125 gas, whereby the Xe-125 decays to I-125 and the I-125 in turn deposits as a solid on the surface of the substrate, the contact being for a time sufficient to deposit at least about 1 microcurie of I-125. I-125 is thereby deposited in a relatively uniform amount over the surface area of the substrate. The substrate is then assayed to determine how much I-125 has been deposited. The substrate is then divided into pieces of measured surface area, each piece therefore containing a measured amount of deposited I-125, and each piece can then be used in the manufacture of an I-125 source.

Multifunctional picoliter droplet manipulation platform and its application in single cell analysis.

PubMed

Gu, Shu-Qing; Zhang, Yun-Xia; Zhu, Ying; Du, Wen-Bin; Yao, Bo; Fang, Qun

2011-10-01

We developed an automated and multifunctional microfluidic platform based on DropLab to perform flexible generation and complex manipulations of picoliter-scale droplets. Multiple manipulations including precise droplet generation, sequential reagent merging, and multistep solid-phase extraction for picoliter-scale droplets could be achieved in the present platform. The system precision in generating picoliter-scale droplets was significantly improved by minimizing the thermo-induced fluctuation of flow rate. A novel droplet fusion technique based on the difference of droplet interfacial tensions was developed without the need of special microchannel networks or external devices. It enabled sequential addition of reagents to droplets on demand for multistep reactions. We also developed an effective picoliter-scale droplet splitting technique with magnetic actuation. The difficulty in phase separation of magnetic beads from picoliter-scale droplets due to the high interfacial tension was overcome using ferromagnetic particles to carry the magnetic beads to pass through the phase interface. With this technique, multistep solid-phase extraction was achieved among picoliter-scale droplets. The present platform had the ability to perform complex multistep manipulations to picoliter-scale droplets, which is particularly required for single cell analysis. Its utility and potentials in single cell analysis were preliminarily demonstrated in achieving high-efficiency single-cell encapsulation, enzyme activity assay at the single cell level, and especially, single cell DNA purification based on solid-phase extraction.

Analysis of close-contact melting with inner wall temperature variation in a horizontal cylindrical capsule

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saitoh, T.S.; Hoshi, Akira

1997-12-31

Melting and solidification of a phase change material (PCM) in a capsule is of practical importance in latent heat thermal energy storage (LHTES) systems which are considered to be very promising to reduce a peak demand of electricity in the summer season. Two melting modes are involved in melting in capsules. One is close-contact melting between the solid bulk and the capsule wall, and another is natural convection melting in the liquid region. In recent years, close-contact melting processes for a single enclosure have been solved using several numerical methods (e.g., Saitoh and Kato (1994)). However, there is no theoreticalmore » solution considering the inner wall temperature variation within cylindrical or spherical capsules. In this report close-contact melting heat transfer characteristics including melt flow in the liquid film under inner wall temperature distribution were analyzed and simple approximate equations are presented, which facilitates designing of the practical capsule bed LHTES systems. The effects of Stefan number and variable temperature profile etc. were clarified in detail. And the melting velocity of the solid bulk under various conditions was also studied theoretically. In addition, the effects of variable inner wall temperature on molten mass fraction were investigated.« less

Fully automated assay of glycohemoglobin with the Abbott IMx analyzer: novel approaches for separation and detection.

PubMed

Wilson, D H; Bogacz, J P; Forsythe, C M; Turk, P J; Lane, T L; Gates, R C; Brandt, D R

1993-10-01

We describe a novel assay for measuring glycohemoglobin directly from anticoagulated whole blood with the Abbott IMx analyzer. The glycohemoglobin is labeled with a soluble polyanionic affinity reagent and the anionic complex is then captured with a cationic solid-phase matrix. Glycohemoglobin is quantified by measuring the quenching by heme of the static fluorescence from an added fluorophore. The assay is standardized to report both percent total glycohemoglobin (%GHb) and percent hemoglobin A1c (%HbA1c). Glucose, bilirubin, triglycerides, labile fraction, and hemoglobin variants do not interfere in the assay. Within- and between-run CVs are approximately 4-5%, with total CVs of approximately 6.5%. Highly significant linear correlations (r > 0.97) were obtained in comparison studies with two major assay methodologies. The time to obtain one result is approximately 10 min (including assay of a control), 56 min for 22 results. We describe the development, standardization, and validation of this new method.

Solid-supported nitroso hetero Diels-Alder reactions. 1. Acylnitroso dienophiles: scope and limitations.

PubMed

Krchnák, Viktor; Moellmann, Ute; Dahse, Hans-Martin; Miller, Marvin J

2008-01-01

Polymer-supported acylnitroso dienophiles were prepared and used in hetero Diels-Alder (HDA) reactions with a variety of dienes. The transient acylnitroso dienophiles were prepared in situ from immobilized hydroxamates, which were attached to solid supports via several linkers each cleavable by different cleavage reagents, and served for the synthesis of both N-unsubstituted and N-derivatized HDA adducts. Model compounds were used to (i) optimize reaction conditions for solid-supported HDA reactions, (ii) evaluate the outcome of the reactions with various dienes, (iii) compare relative reactivities of dienes, and (iv) assess the stability of HDA adducts toward cleavage conditions typically used in solid-phase syntheses. Cleaved products were submitted to biological assays, and the results are reported. The accompanying paper, focused on complementary arylnitroso HDA reactions, includes a comparison of both HDA reactions.

Measuring the Nonuniform Evaporation Dynamics of Sprayed Sessile Microdroplets with Quantitative Phase Imaging.

PubMed

Edwards, Chris; Arbabi, Amir; Bhaduri, Basanta; Wang, Xiaozhen; Ganti, Raman; Yunker, Peter J; Yodh, Arjun G; Popescu, Gabriel; Goddard, Lynford L

2015-10-13

We demonstrate real-time quantitative phase imaging as a new optical approach for measuring the evaporation dynamics of sessile microdroplets. Quantitative phase images of various droplets were captured during evaporation. The images enabled us to generate time-resolved three-dimensional topographic profiles of droplet shape with nanometer accuracy and, without any assumptions about droplet geometry, to directly measure important physical parameters that characterize surface wetting processes. Specifically, the time-dependent variation of the droplet height, volume, contact radius, contact angle distribution along the droplet's perimeter, and mass flux density for two different surface preparations are reported. The studies clearly demonstrate three phases of evaporation reported previously: pinned, depinned, and drying modes; the studies also reveal instances of partial pinning. Finally, the apparatus is employed to investigate the cooperative evaporation of the sprayed droplets. We observe and explain the neighbor-induced reduction in evaporation rate, that is, as compared to predictions for isolated droplets. In the future, the new experimental methods should stimulate the exploration of colloidal particle dynamics on the gas-liquid-solid interface.

Composite materials for thermal energy storage

DOEpatents

Benson, David K.; Burrows, Richard W.; Shinton, Yvonne D.

1986-01-01

The present invention discloses composite material for thermal energy storage based upon polyhydric alcohols, such as pentaerythritol, trimethylol ethane (also known as pentaglycerine), neopentyl glycol and related compounds including trimethylol propane, monoaminopentaerythritol, diamino-pentaerythritol and tris(hydroxymethyl)acetic acid, separately or in combinations, which provide reversible heat storage through crystalline phase transformations. These phase change materials do not become liquid during use and are in contact with at least one material selected from the group consisting of metals, carbon siliceous, plastic, cellulosic, natural fiber, artificial fiber, concrete, gypsum, porous rock, and mixtures thereof. Particulate additions, such as aluminum or graphite powders, as well as metal and carbon fibers can also be incorporated therein. Particulate and/or fibrous additions can be introduced into molten phase change materials which can then be cast into various shapes. After the phase change materials have solidified, the additions will remain dispersed throughout the matrix of the cast solid. The polyol is in contact with at least one material selected from the group consisting of metals, carbon siliceous, plastic, cellulosic, natural fiber, artificial fiber, concrete, gypsum, and mixtures thereof.

Surface topographical changes measured by phase-locked interferometry

NASA Technical Reports Server (NTRS)

Lauer, J. L.; Fung, S. S.

1984-01-01

An electronic optical laser interferometer capable of resolving depth differences of as low as 30 A and planar displacements of 6000 A was constructed to examine surface profiles of bearing surfaces without physical contact. Topological chemical reactivity was determined by applying a drop of dilute alcoholic hydrochloric acid and measuring the profile of the solid surface before and after application of this probe. Scuffed bearing surfaces reacted much faster than virgin ones but that bearing surfaces exposed to lubricants containing an organic chloride reacted much more slowly. The reactivity of stainless steel plates, heated in a nitrogen atmosphere to different temperatures, were examined later at ambient temperature. The change of surface contour as a result of the probe reaction followed Arrhenius-type relation with respect to heat treatment temperature. The contact area of the plate of a ball/plate sliding elastohydrodynamic contact run on trimethylopropane triheptanoate with or without additives was optically profiled periodically. As scuffing was approached, the change of profile within the contact region changed much more rapidly by the acid probe and assumed a constant high value after scuffing. A nonetching metallurgical phase was found in the scuff mark, which was apparently responsible for the high reactivity.

Study of the Relationship between Boundary Slip and Nanobubbles on a Smooth Hydrophobic Surface.

PubMed

Li, Dayong; Jing, Dalei; Pan, Yunlu; Bhushan, Bharat; Zhao, Xuezeng

2016-11-01

Surface nanobubbles, which are nanoscopic or microscopic gaseous domains forming at the solid/liquid interface, have a strong impact on the interface by changing the two-phase contact to a three-phase contact. Therefore, they are believed to affect the boundary condition and liquid flow. However, there are still disputes in the theoretical studies as to whether the nanobubbles can increase the slip length effectively. Furthermore, there are still no direct experimental studies to support either side. Therefore, an intensive study on the effective slip length for flows over bare surfaces with nanobubbles is essential for establishing the relation between nanobubbles and slip length. Here, we study the effect of nanobubbles on the slippage experimentally and theoretically. Our experimental results reveal an increase from 8 to 512 nm in slip length by increasing the surface coverage of nanobubbles from 1.7 to 50.8% and by decreasing the contact angle of nanobubbles from 42.8 to 16.6°. This is in good agreement with theoretical results. Our results indicate that nanobubbles could always act as a lubricant and significantly increase the slip length. The surface coverage, height, and contact angle are key factors for nanobubbles to reduce wall friction.

Difference between beta1-adrenoceptor autoantibodies of human and animal origin-Limitations detecting beta1-adrenoceptor autoantibodies using peptide based ELISA technology.

PubMed

Wenzel, Katrin; Schulze-Rothe, Sarah; Müller, Johannes; Wallukat, Gerd; Haberland, Annekathrin

2018-01-01

Cell-based analytics for the detection of the beta1-adrenoceptor autoantibody (beta1-AAB) are functional, yet difficult to handle, and should be replaced by easily applicable, routine lab methods. Endeavors to develop solid-phase-based assays such as ELISA to exploit epitope moieties for trapping autoantibodies are ongoing. These solid-phase-based assays, however, are often unreliable when used with human patient material, in contrast to animal derived autoantibodies. We therefore tested an immunogen peptide-based ELISA for the detection of beta1-AAB, and compared commercially available goat antibodies against the 2nd extracellular loop of human beta1-adrenoceptor (ADRB1-AB) to autoantibodies enriched from patient material. The functionality of these autoantibodies was tested in a cell based assay for comparison and their structural appearance was investigated using 2D gel electrophoresis. The ELISA showed a limit of detection for ADRB1-AB of about 1.5 nmol antibody/L when spiked in human control serum and only about 25 nmol/L when spiked in species identical (goat) matrix material. When applied to samples of human origin, the ELISA failed to identify the specific beta1-AABs. A low concentration of beta1-AAB, together with structural inconsistency of the patient originated samples as seen from the 2D Gel appearance, might contribute to the failure of the peptide based ELISA technology to detect human beta1-AABs.

Acrylamide: formation, occurrence in food products, detection methods, and legislation.

PubMed

Arvanitoyannis, Ioannis S; Dionisopoulou, Niki

2014-01-01

This review aims at summarizing the most recent updates in the field of acrylamide (AA) formation (mechanism, conditions) and the determination of AA in a number of foods (fried or baked potatoes, chips, coffee, bread, etc). The methods applied for AA detection [Capillary Electrophoresis-Mass Spectrometry (CE-MS), Liquid Chromatography-Mass Spectrometry (LC-MS), Non-Aqueous Capillary Electrophoresis (NACE), High Performance Liquid Chromatography-Mass Spectrometry (HPLC-MS), Pressurized Fluid Extraction (PFE), Matrix Solid-Phase Dispersion (MSPD), Gas Chromatography-Mass Spectrometry (GC-MS), Solid-Phase MicroExtraction-Gas Chromatography (SPME-GC), Enzyme Linked Immunosorbent Assay (ELISA), and MicroEmulsion ElectroKinetic Chromatography (MEEKC) are presented and commented. Several informative figures and tables are included to show the effect of conditions (temperature, time) on the AA formation. A section is also included related to AA legislation in EU and US.

Real-time biochemical assay telemetering system

NASA Technical Reports Server (NTRS)

Kern, Roger G. (Inventor); Mintz, Frederick W. (Inventor); Richards, Gil F. (Inventor); Kidwell, David A. (Inventor)

1999-01-01

The present invention is an apparatus and a method of detecting a chemical released by perspiration, typically through sweat and broadcasting the detection to a receiver. The chemical may be a drug of abuse. The device which is attached to the skin of a subject contains labeled antibodies or label containing microspheres attached to antibodies. The labeled antibodies are bound to solid phase drug via antigen-antibody interaction. These labeled antibodies are displaced from the solid phase support to which they are bound by free drug molecules in the perspiration. These labeled antibodies then migrate through a spacer layer and are trapped by a layer containing a suitable selective binding material. The label is illuminated or excited by a light source and detected by a photodetector. The signal can be recorded, or transmitted to a remote radio monitor.

On the equilibrium contact angle of sessile liquid drops from molecular dynamics simulations.

PubMed

Ravipati, Srikanth; Aymard, Benjamin; Kalliadasis, Serafim; Galindo, Amparo

2018-04-28

We present a new methodology to estimate the contact angles of sessile drops from molecular simulations by using the Gaussian convolution method of Willard and Chandler [J. Phys. Chem. B 114, 1954-1958 (2010)] to calculate the coarse-grained density from atomic coordinates. The iso-density contour with average coarse-grained density value equal to half of the bulk liquid density is identified as the average liquid-vapor (LV) interface. Angles between the unit normal vectors to the average LV interface and unit normal vector to the solid surface, as a function of the distance normal to the solid surface, are calculated. The cosines of these angles are extrapolated to the three-phase contact line to estimate the sessile drop contact angle. The proposed methodology, which is relatively easy to implement, is systematically applied to three systems: (i) a Lennard-Jones (LJ) drop on a featureless LJ 9-3 surface; (ii) an SPC/E water drop on a featureless LJ 9-3 surface; and (iii) an SPC/E water drop on a graphite surface. The sessile drop contact angles estimated with our methodology for the first two systems are shown to be in good agreement with the angles predicted from Young's equation. The interfacial tensions required for this equation are computed by employing the test-area perturbation method for the corresponding planar interfaces. Our findings suggest that the widely adopted spherical-cap approximation should be used with caution, as it could take a long time for a sessile drop to relax to a spherical shape, of the order of 100 ns, especially for water molecules initiated in a lattice configuration on a solid surface. But even though a water drop can take a long time to reach the spherical shape, we find that the contact angle is well established much faster and the drop evolves toward the spherical shape following a constant-contact-angle relaxation dynamics. Making use of this observation, our methodology allows a good estimation of the sessile drop contact angle values even for moderate system sizes (with, e.g., 4000 molecules), without the need for long simulation times to reach the spherical shape.

On the equilibrium contact angle of sessile liquid drops from molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Ravipati, Srikanth; Aymard, Benjamin; Kalliadasis, Serafim; Galindo, Amparo

2018-04-01

We present a new methodology to estimate the contact angles of sessile drops from molecular simulations by using the Gaussian convolution method of Willard and Chandler [J. Phys. Chem. B 114, 1954-1958 (2010)] to calculate the coarse-grained density from atomic coordinates. The iso-density contour with average coarse-grained density value equal to half of the bulk liquid density is identified as the average liquid-vapor (LV) interface. Angles between the unit normal vectors to the average LV interface and unit normal vector to the solid surface, as a function of the distance normal to the solid surface, are calculated. The cosines of these angles are extrapolated to the three-phase contact line to estimate the sessile drop contact angle. The proposed methodology, which is relatively easy to implement, is systematically applied to three systems: (i) a Lennard-Jones (LJ) drop on a featureless LJ 9-3 surface; (ii) an SPC/E water drop on a featureless LJ 9-3 surface; and (iii) an SPC/E water drop on a graphite surface. The sessile drop contact angles estimated with our methodology for the first two systems are shown to be in good agreement with the angles predicted from Young's equation. The interfacial tensions required for this equation are computed by employing the test-area perturbation method for the corresponding planar interfaces. Our findings suggest that the widely adopted spherical-cap approximation should be used with caution, as it could take a long time for a sessile drop to relax to a spherical shape, of the order of 100 ns, especially for water molecules initiated in a lattice configuration on a solid surface. But even though a water drop can take a long time to reach the spherical shape, we find that the contact angle is well established much faster and the drop evolves toward the spherical shape following a constant-contact-angle relaxation dynamics. Making use of this observation, our methodology allows a good estimation of the sessile drop contact angle values even for moderate system sizes (with, e.g., 4000 molecules), without the need for long simulation times to reach the spherical shape.

Solid-phase materials for chelating metal ions and methods of making and using same

DOEpatents

Harrup, Mason K.; Wey, John E.; Peterson, Eric S.

2003-06-10

A solid material for recovering metal ions from aqueous streams, and methods of making and using the solid material, are disclosed. The solid material is made by covalently bonding a chelating agent to a silica-based solid, or in-situ condensing ceramic precursors along with the chelating agent to accomplish the covalent bonding. The chelating agent preferably comprises a oxime type chelating head, preferably a salicylaldoxime-type molecule, with an organic tail covalently bonded to the head. The hydrocarbon tail includes a carbon-carbon double bond, which is instrumental in the step of covalently bonding the tail to the silica-based solid or the in-situ condensation. The invented solid material may be contacted directly with aqueous streams containing metal ions, and is selective to ions such as copper (II) even in the presence of such ions as iron (III) and other materials that are present in earthen materials. The solid material with high selectivity to copper may be used to recover copper from mining and plating industry streams, to replace the costly and toxic solvent extraction steps of conventional copper processing.

Core-Shell Fe1- xS@Na2.9PS3.95Se0.05 Nanorods for Room Temperature All-Solid-State Sodium Batteries with High Energy Density.

PubMed

Wan, Hongli; Mwizerwa, Jean Pierre; Qi, Xingguo; Liu, Xin; Xu, Xiaoxiong; Li, Hong; Hu, Yong-Sheng; Yao, Xiayin

2018-03-27

High ionic conductivity electrolyte and intimate interfacial contact are crucial factors to realize high-performance all-solid-state sodium batteries. Na 2.9 PS 3.95 Se 0.05 electrolyte with reduced particle size of 500 nm is first synthesized by a simple liquid-phase method and exhibits a high ionic conductivity of 1.21 × 10 -4 S cm -1 , which is comparable with that synthesized with a solid-state reaction. Meanwhile, a general interfacial architecture, that is, Na 2.9 PS 3.95 Se 0.05 electrolyte uniformly anchored on Fe 1- x S nanorods, is designed and successfully prepared by an in situ liquid-phase coating approach, forming core-shell structured Fe 1- x S@Na 2.9 PS 3.95 Se 0.05 nanorods and thus realizing an intimate contact interface. The Fe 1- x S@Na 2.9 PS 3.95 Se 0.05 /Na 2.9 PS 3.95 Se 0.05 /Na all-solid-state sodium battery demonstrates high specific capacity and excellent rate capability at room temperature, showing reversible discharge capacities of 899.2, 795.5, 655.1, 437.9, and 300.4 mAh g -1 at current densities of 20, 50, 100, 150, and 200 mA g -1 , respectively. The obtained all-solid-state sodium batteries show very high energy and power densities up to 910.6 Wh kg -1 and 201.6 W kg -1 based on the mass of Fe 1- x S at current densities of 20 and 200 mA g -1 , respectively. Moreover, the reaction mechanism of Fe 1- x S is confirmed by means of ex situ X-ray diffraction techniques, showing that partially reversible reaction occurs in the Fe 1- x S electrode after the second cycle, which gives the obtained all-solid-state sodium battery an exceptional cycling stability, exhibiting a high capacity of 494.3 mAh g -1 after cycling at 100 mA g -1 for 100 cycles. This contribution provides a strategy for designing high-performance room temperature all-solid-state sodium battery.

Scenarios of stable Vapor→Liquid Droplet→Solid Nanowire growth

NASA Astrophysics Data System (ADS)

Nebol`sin, Valery A.; Dunaev, Alexander I.; Tatarenkov, Alexander F.; Shmakova, Svetlana S.

2016-09-01

In the process of Nanowire (NW) growth under the Vapor→Liquid Droplet→Solid (VLS) scheme, the stages that reach the boundary of the crystallization front (the triple phase line (TPL)) under the droplet of the catalyst are either absorbed by the TPL, or accumulate ahead of it. It has been shown that, in the first case, TPL can release stages, which leads to a decrease in supersaturation necessary for NW growth. An equation has been derived, which defines the change in free surface energy of the three-phase system in the absorption (release) of a stage, being a function of the contact angle of the droplet, and the ratio between the phase conjugation angles interface at equilibrium shift in the boundary line. A thermodynamic model has been developed and three possible scenarios for sustainable NW growth: Non-Wetting, Wetting and Fully Wetting have been considered in accordance with the processes occurring at the interface of three phases. The results obtained for each scenario were used to analyze the polytypism of GaAs and InAs NW, the radial periodic instability of Si NW and the formation of "negative" NW.

Bioassessment Methodologies for the Regulatory Testing of Freshwater Dredged Material. Proceedings of a Workshop.

DTIC Science & Technology

1986-06-01

of the metabolic effects of exposure to the suspended solid phase during the screening experiments with only modest additional costs. Like- .. wise...assays MUST continue for 10 days, durinq which time daily records must be kept of salinity , temperature, DO, obvious mortalities and any sublethal effects ...25 Adenylate Energy Charge. ................. 26 . Oxygen Consumption and Osmoregulation . .......... 26 Miscellaneous. ..................... 26

Interactions of Rodent Coronaviruses with Cellular Receptors

DTIC Science & Technology

2016-05-08

ocular porphyrin discharges from inflamed lacrimal glands, and sneezing caused by acute rhinitis and photophobia. other changes caused by rat...hepatitis virus which share the same appearance in negative stains, recalling a solar corona , should be included in a group which they suggested...sialodacryoadenitis virus (SDAV) (Percy et al., 1989). Because of this breakthrough and the development of solid phase corona virus receptor assays in our

[Detection of antibodies against Lamblia antigens in serum from atopic patients].

PubMed

Akhapkina, I G

2004-04-01

The method of solid-phase immune-enzyme assay was used to test the sera of atopic patients for the purpose of detecting IgG to lamblias. A high degree of protozoal invasion was established especially among pre-school and school children. It was proven as expedient to make the serological examinations of atopic patients in cases the clinical finding is unclear.

Effect of Reaction Pathway on the Extent and Mechanism of Uranium(VI) Immobilization with Calcium and Phosphate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehta, Vrajesh S.; Maillot, Fabien; Wang, Zheming

Phosphate addition to subsurface environments contaminated with uranium can be used as an in situ remediation approach. Batch experiments were conducted to evaluate the dependence of the extent and mechanism of uranium uptake on the pathway for reaction with calcium phosphates. At pH 4.0 and 6.0 uranium uptake occurred via autunite (Ca(UO2)(PO4)3) precipitation irrespective of the starting forms of calcium and phosphate. At pH 7.5, the uptake mechanism depended on the nature of the calcium and phosphate. When dissolved uranium, calcium, and phosphate were added simultaneously, uranium was structurally incorporated into a newly formed amorphous calcium phosphate solid. Adsorption wasmore » the dominant removal mechanism for uranium contacted with pre-formed amorphous calcium phosphate solids,. When U(VI) was added to a suspension containing amorphous calcium phosphate solids as well as dissolved calcium and phosphate, then removal occurred through precipitation (57±4 %) of autunite and adsorption (43±4 %) onto calcium phosphate. The solid phase speciation of the uranium was determined using X-ray absorption spectroscopy and laser induced fluorescence spectroscopy. Dissolved uranium, calcium, and phosphate concentrations with saturation index calculations helped identify removal mechanisms and determine thermodynamically favorable solid phases.« less

Numerical study on the stick-slip motion of contact line moving on heterogeneous surfaces

NASA Astrophysics Data System (ADS)

Liu, Ming; Chen, Xiao-Peng

2017-08-01

We present a numerical study of a moving contact line (CL) crossing the intersecting region of hydrophilic and hydrophobic patterns on a solid wall using lattice Boltzmann methods (LBMs). To capture the interface between the two phases properly, we applied a phase field model coupled with the LBM. The evolutions of the CL velocity, dynamic contact angle, and apparent contact angle are analyzed for the so-called "stick" and "slip" processes. In the two processes, the evolution of the quantities follows different rules shortly after the initial quick transition, which is probably caused by finite interfacial thickness or non-equilibrium effects. For the stick process, the CL is almost fixed and energy is extracted from the main flow to rebuild the meniscus' profile. The evolution of the meniscus is mainly governed by mass conservation. The CL is depinned after the apparent contact angle surpasses the dynamic one, which implies that the interfacial segment in the vicinity of contact line is bended. For the slip process, the quantities evolve with features of relaxation. In the microscopic scale, the velocity of the CL depends on the balance between unbalanced Young's capillary force and viscous drag. To predict the apparent contact angle evolution, a model following the dynamics of an overdamped spring-mass system is proposed. Our results also show that the capillary flows in a channel with heterogeneous wall can be described generally with the Poiseuille flow superimposed by the above transient one.

A selective and sensitive high performance liquid chromatography assay for the determination of cycloserine in human plasma.

PubMed

Hemanth Kumar, A K; Polisetty, Arun Kumar; Sudha, V; Vijayakumar, A; Ramachandran, Geetha

2018-04-01

Cycloserine (CYC) is a second line antitubercular drug that is used for the treatment of multidrug resistant tuberculosis (MDR-TB) along with other antitubercular agents and is often used in developing countries. Monitoring CYC levels in plasma could be useful in the clinical management of patients with MDR-TB. A high performance liquid chromatography method for the determination of CYC in human plasma was developed. The method involved extraction of the sample using solid phase extraction cartridges and analysis of the extracted sample using a reverse phase T3 column (150mm) and detection at 240nm with Photo Diode Array (PDA) detector. The chromatogram was run for 15min at a flow rate of 0.4ml/min at 30°C. The assay was specific for CYC and linear from 5.0 to 50.0μg/ml. The relative standard deviations of within- and between-day assays were less than 10%. Recovery of CYC ranged from 102% to 109%. The interference of other second line anti-TB drugs in the assay of CYC was ruled out. The assay spans the concentration range of clinical interest. The specificity and sensitivity of this assay makes it highly suitable for pharmacokinetic studies. Copyright © 2017 Tuberculosis Association of India. Published by Elsevier B.V. All rights reserved.

Use of Bispecific Antibodies in Molecular Velcro Assays Whose Specificity Approaches the Theoretical Limit of Immunodetection for Bordetella pertussis

PubMed Central

Tang, X. L.; Peppler, M. S.; Irvin, R. T.; Suresh, M. R.

2004-01-01

A bispecific monoclonal antibody (bsMAb) that detects Bordetella pertussis, the causative agent of whooping cough, and horseradish peroxidase (HRPO) has been developed by use of the quadroma technology. A quadroma, P123, was produced by fusing two well-characterized hybridomas against the bacterium and the enzyme and was subcloned to obtain a stable bsMAb-secreting cell line. The quadroma was theoretically expected to produce up to 10 different molecular species of immunoglobulins, so secreted bispecific antibody was complexed with excess HRPO and the HRPO-bsMAb complex was purified in one step by benzhydroxamic acid-agarose affinity cochromatography. An ultrasensitive homosandwich molecular “velcro” enzyme-linked immunosorbent assay for the detection of B. pertussis whole bacteria with HRPO-bsMAb was established in both microplate and nasopharyngeal swab formats. This assay demonstrates a high sensitivity that approaches the theoretical limit of detection of one bacterium. This new nanoprobe can be used to develop a new generation of assays that are simple, inexpensive alternatives to quantitative PCR and that can be used by clinical laboratories. This strategy of homosandwich assays with solid-phase monospecific antibodies and solution-phase bsMAb with specificity for the same repeating surface determinants can be applied to generate ultrasensitive immunodiagnostic assays for viruses and bacteria. PMID:15242951

Solid-phase microextraction and chiral HPLC analysis of ibuprofen in urine.

PubMed

de Oliveira, Anderson Rodrigo Moraes; Cesarino, Evandro José; Bonato, Pierina Sueli

2005-04-25

A simple and rapid solid-phase microextraction method was developed for the enantioselective analysis of ibuprofen in urine. The sampling was made with a polydimethylsiloxane-divinylbenzene coated fiber immersed in the liquid sample. After desorptioning from the fiber, ibuprofen enantiomers were analyzed by HPLC using a Chiralpak AD-RH column and UV detection. The mobile phase was made of methanol-pH 3.0 phosphoric acid solution (75:25, v/v), at a flow rate of 0.45 mL/min. The mean recoveries of SPME were 19.8 and 19.1% for (-)-R-ibuprofen and (+)-(S)-ibuprofen, respectively. The method was linear at the range of 0.25-25 microg/mL. Within-day and between-day assay precision and accuracy were below 15% for both ibuprofen enantiomers at concentrations of 0.75, 7.5 and 20 microg/mL. The method was tested with urine quality control samples and human urine fractions after administration of 200 mg rac-ibuprofen.

Automated solid-phase extraction and liquid chromatography for assay of cyclosporine in whole blood.

PubMed

Kabra, P M; Wall, J H; Dimson, P

1987-12-01

In this rapid, precise, accurate, cost-effective, automated liquid-chromatographic procedure for determining cyclosporine in whole blood, the cyclosporine is extracted from 0.5 mL of whole blood together with 300 micrograms of cyclosporin D per liter, added as internal standard, by using an Advanced Automated Sample Processing unit. The on-line solid-phase extraction is performed on an octasilane sorbent cartridge, which is interfaced with a RP-8 guard column and an octyl analytical column, packed with 5-microns packing material. Both columns are eluted with a mobile phase containing acetonitrile/methanol/water (53/20/27 by vol) at a flow rate of 1.5 mL/min and column temperature of 70 degrees C. Absolute recovery of cyclosporine exceeded 85% and the standard curve was linear to 5000 micrograms/L. Within-run and day-to-day CVs were less than 8%. Correlation between automated and manual Bond-Elut extraction methods was excellent (r = 0.987). None of 18 drugs and four steroids tested interfered.

Determination and validation of a simple high-performance liquid chromatographic method for simultaneous assay of iprodione and vinclozolin in human urine.

PubMed

Carlucci, Giuseppe; Pasquale, Dorina Di; Ruggieri, Fabrizio; Mazzeo, Pietro

2005-12-15

A method based on solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) was developed for the simultaneous determination of 3-(3,5-diclorophenyl)-5-ethenyl-5-methyl-2,4-oxazolidinedione (vinclozolin) and 3-(3,5-diclorophenyl)-N-(1-methylethyl)-2,4-dioxo-1-imidazolidinecarboxamide (iprodione) in human urine. Urine samples containing vinclozolin and iprodione were collected by solid phase extraction using C(18) cartridges. The chromatographic separation was achieved on a Spherisorb ODS2 (250 mm x 4.6 mm, 5 microm) column with an isocratic mobile phase of acetonitrile-water (60:40, v/v). Detection was UV absorbance at 220 nm. The calibration graphs were linear from 30 to 1000 ng/mL for the two fungicides. Intra- and inter-day R.S.D. did not exceed 2.9%. The quantitation limit was 50 ng/mL for vinclozolin and 30 ng/mL for iprodione, respectively.

Application of phase-trafficking methods to natural products research.

PubMed

Araya, Juan J; Montenegro, Gloria; Mitscher, Lester A; Timmermann, Barbara N

2010-09-24

A novel simultaneous phase-trafficking approach using spatially separated solid-supported reagents for rapid separation of neutral, basic, and acidic compounds from organic plant extracts with minimum labor is reported. Acidic and basic ion-exchange resins were physically separated into individual sacks ("tea bags") for trapping basic and acidic compounds, respectively, leaving behind in solution neutral components of the natural mixtures. Trapped compounds were then recovered from solid phase by appropriate suspension in acidic or basic solutions. The feasibility of the proposed separation protocol was demonstrated and optimized with an "artificial mixture" of model compounds. In addition, the utility of this methodology was illustrated with the successful separation of the alkaloid skytanthine from Skytanthus acutus Meyen and the main catechins and caffeine from Camellia sinensis L. (Kuntze). This novel approach offers multiple advantages over traditional extraction methods, as it is not labor intensive, makes use of only small quantities of solvents, produces fractions in adequate quantities for biological assays, and can be easily adapted to field conditions for bioprospecting activities.

Application of Phase-Trafficking Methods to Natural Products Research

PubMed Central

Araya, Juan J.; Montenegro, Gloria; Mitscher, Lester A.; Timmermann, Barbara N.

2010-01-01

A novel simultaneous phase-trafficking approach using spatially separated solid-supported reagents (SSR) for rapid separation of neutral, basic, and acidic compounds from organic plant extracts with minimum labor is reported. Acidic and basic ion exchange resins were physically separated into individual sacks (“teabags”) for trapping basic and acidic compounds respectively, leaving behind in solution neutral components of the natural mixtures. Trapped compounds were then recovered from solid phase by appropriate suspension in acidic or basic solutions. The feasibility of the proposed separation protocol was demonstrated and optimized with an “artificial mixture” of model compounds. In addition, the utility of this methodology was illustrated with the successful separation of the alkaloid skytanthine from Skytanthus acutus Meyen and the main catechins and caffeine from Camellia sinensis L. (Kuntze). This novel approach offers multiple advantages over traditional extraction methods, as it is not labor intensive, makes use of only small quantities of solvents, produces fractions in adequate quantities for biological assays, and can be easily adapted to field conditions for bioprospecting activities. PMID:20704309

A simple and sensitive enzymatic method for cholesterol quantification in macrophages and foam cells

PubMed Central

Robinet, Peggy; Wang, Zeneng; Hazen, Stanley L.; Smith, Jonathan D.

2010-01-01

A precise and sensitive method for measuring cellular free and esterified cholesterol is required in order to perform studies of macrophage cholesterol loading, metabolism, storage, and efflux. Until now, the use of an enzymatic cholesterol assay, commonly used for aqueous phase plasma cholesterol assays, has not been optimized for use with solid phase samples such as cells, due to inefficient solubilization of total cholesterol in enzyme compatible solvents. We present an efficient solubilization protocol compatible with an enzymatic cholesterol assay that does not require chemical saponification or chromatographic separation. Another issue with enzyme compatible solvents is the presence of endogenous peroxides that interfere with the enzymatic cholesterol assay. We overcame this obstacle by pretreatment of the reaction solution with the enzyme catalase, which consumed endogenous peroxides resulting in reduced background and increased sensitivity in our method. Finally, we demonstrated that this method for cholesterol quantification in macrophages yields results that are comparable to those measured by stable isotope dilution gas chromatography with mass spectrometry detection. In conclusion, we describe a sensitive, simple, and high-throughput enzymatic method to quantify cholesterol in complex matrices such as cells. PMID:20688754

LC-MS/MS assay for the quantitation of the tyrosine kinase inhibitor neratinib in human plasma.

PubMed

Kiesel, Brian F; Parise, Robert A; Wong, Alvin; Keyvanjah, Kiana; Jacobs, Samuel; Beumer, Jan H

2017-02-05

Neratinib is an orally available tyrosine kinase inhibitor targeting HER2 (ERBB2) and EGFR (ERBB). It is being clinically evaluated for the treatment of breast and other solid tumors types as a single agent or in combination with other chemotherapies. In support of several phase I/II clinical trials investigating neratinib combinations, we developed and validated a novel LC-MS/MS assay for the quantification of neratinib in 100μL of human plasma with a stable isotopic internal standard. Analytes were extracted from plasma using protein precipitation and evaporation of the resulting supernatant followed by resuspension. Chromatographic separation was achieved using an Acquity UPLC BEH Shield RP18 column and a gradient methanol-water mobile phase containing 10% ammonium acetate. An ABI 4000 mass spectrometer and electrospray positive mode ionization were used for detection. The assay was linear from 2 to 1,000ng/mL and proved to be accurate (98.9-106.5%) and precise (<6.2%CV), and met the FDA guidance for bioanalytical method validation. This LC-MS/MS assay will be an essential tool to further define the pharmacokinetics of neratinib. Copyright © 2016 Elsevier B.V. All rights reserved.

Antibody binding in altered gravity: implications for immunosorbent assay during space flight

NASA Technical Reports Server (NTRS)

Maule, Jake; Fogel, Marilyn; Steele, Andrew; Wainwright, Norman; Pierson, Duane L.; McKay, David S.

2003-01-01

A single antibody-incubation step of an indirect, enzyme-linked immunosorbent assay (ELISA) was performed during microgravity, Martian gravity (0.38 G) and hypergravity (1.8 G) phases of parabolic flight, onboard the NASA KC-135 aircraft. Antibody-antigen binding occurred within 15 seconds; the level of binding did not differ between microgravity, Martian gravity and 1 G (Earth's gravity) conditions. During hypergravity and 1 G, antibody binding was directly proportional to the fluid volume (per microtiter well) used for incubation; this pattern was not observed during microgravity. These effects in microgravity may be due to "fluid spread" within the chamber (observed during microgravity with digital photography), leading to greater fluid-surface contact and subsequently antibody-antigen contact. In summary, these results demonstrate that: i) ELISA antibody-incubation and washing steps can be successfully performed by human operators during microgravity, Martian gravity and hypergravity; ii) there is no significant difference in antibody binding between microgravity, Martian gravity and 1 G conditions; and iii) a smaller fluid volume/well (and therefore less antibody) was required for a given level of binding during microgravity. These conclusions indicate that reduced gravity would not present a barrier to successful operation of immunosorbent assays during spaceflight.

Resolved simulations of a granular-fluid flow through a check dam with a SPH-DCDEM model

NASA Astrophysics Data System (ADS)

Birjukovs Canelas, Ricardo; Domínguez, Jose; Crespo, Alejandro; Gómez-Gesteira, Moncho; Ferreira, Rui M. L.

2017-04-01

Debris flows represent some of the most relevant phenomena in geomorphological events. Due to the potential destructiveness of such flows, they are the target of a vast amount of research. Experimental research in laboratory facilities or in the field is fundamental to characterize the fundamental rheological properties of these flows and to provide insights on its structure. However, characterizing interparticle contacts and the structure of the motion of the granular phase is difficult, even in controlled laboratory conditions, and possible only for simple geometries. This work addresses the need for a numerical simulation tool applicable to granular-fluid mixtures featuring high spatial and temporal resolution, thus capable of resolving the motion of individual particles, including all interparticle contacts and susceptible to complement laboratory research. The DualSPHysics meshless numerical implementation based on Smoothed Particle Hydrodynamics (SPH) is expanded with a Distributed Contact Discrete Element Method (DCDEM) in order to explicitly solve the fluid and the solid phase. The specific objective is to test the SPH-DCDEM approach by comparing its results with experimental data. An experimental set-up for stony debris flows in a slit check dam is reproduced numerically, where solid material is introduced through a hopper assuring a constant solid discharge for the considered time interval. With each sediment particle possibly undergoing several simultaneous contacts, thousands of time-evolving interactions are efficiently treated due to the model's algorithmic structure and the HPC implementation of DualSPHysics. The results, comprising mainly of retention curves, are in good agreement with the measurements, correctly reproducing the changes in efficiency with slit spacing and density. The encouraging results, coupled with the prospect of so far unique insights into the internal dynamics of a debris flow show the potential of high-performance resolved approaches to the description of the flow and the study of its mitigation strategies. This research as partially supported by Portuguese and European funds, within programs COMPETE2020 and PORL-FEDER, through project PTDC/ECM-HID/6387/2014 granted by the National Foundation for Science and Technology (FCT).

Combustion mechanism of double-base propellant containing nitrogen heterocyclic nitroamines (II): The temperature distribution of the flame and its chemical structure

NASA Astrophysics Data System (ADS)

Yan, Qi-Long; Song, Zhen-Wei; Shi, Xiao-Bing; Yang, Zhi-Yuan; Zhang, Xiao-Hong

2009-03-01

In order to evaluate the actual pros and cons in the use of new nitroamines for solid rocket applications, the combustion properties of double-base propellants containing nitrogen heterocyclic nitroamines such as RDX, TNAD, HMX and DNP are investigated by means of high-speed photography technique, Non-contact wavelet-based measurement of flame temperature distribution. The chemical reactions in different combustion zone which control the burning characteristics of the double-base propellant containing nitrogen heterocyclic nitroamines were systematically investigated and descriptions of the detailed thermal decomposition mechanisms from solid phase to liquid phase or to gas phase are also included. It was indicated that the thermodynamic phase transition consisting of both evaporation and condensation of NC+NG, HMX, TNAD, RDX and DNP, are considered to provide a complete description of the mass transfer process in the combustion of these double-base propellants, and the combustion mechanisms of them are mainly involved with the oxidation mechanism of the NO 2, formaldehyde (CH 2O) and hydrogen cyanide (HCN). The entire oxidation reaction rate might be dependent on the pressure of the combustion chamber and temperature of the gas phase.

Shear test on viscoelastic granular material using Contact Dynamics simulations

NASA Astrophysics Data System (ADS)

Quezada, Juan Carlos; Sagnol, Loba; Chazallon, Cyrille

2017-06-01

By means of 3D contact dynamic simulations, the behavior of a viscoelastic granular material under shear loading is investigated. A viscoelastic fluid phase surrounding the solid particles is simulated by a contact model acting between them. This contact law was implemented in the LMGC90 software, based on the Burgers model. This model is able to simulate also the effect of creep relaxation. To validate the proposed contact model, several direct shear tests were performed, experimentally and numerically using the Leutner device. The numerical samples were created using spheres with two particle size distribution, each one identified for two layers from a road structure. Our results show a reasonable agreement between experimental and numerical data regarding the strain-stress evolution curves and the stress levels measured at failure. The proposed model can be used to simulate the mechanical behavior of multi-layer road structure and to study the influence of traffic on road deformation, cracking and particles pull-out induced by traffic loading.

An enzyme immunoassay for rat growth hormone - Applications to the study of growth hormone variants

NASA Technical Reports Server (NTRS)

Farrington, Marianne A.; Hymer, W. C.

1987-01-01

A sensitive and specific competitive enzyme immunoassay for rat growth hormone (GH) is described and its use in the detection of GH variants is demonstrated. In the present assay, soluble GH and GH adsorbed to a solid-phase support compete for monkey anti-GH antibody binding sites. The immobilized antibody-GH complex is detected and quantified using goat antimonkey immunoglobin G covalently conjugated to horseradish peroxidase. It is noted that the assay can be performed in 27 hours and that sensitivities in the range of 0.19 to 25 ng can be obtained in the region of 10 to 90 percent binding.

Comparison of advanced thermal and electrical storage for parabolic dish solar thermal power systems

NASA Astrophysics Data System (ADS)

Fujita, T.; Birur, G. C.; Schredder, J. M.; Bowyer, J. M.; Awaya, H. I.

Parabolic dish solar concentrator cluster concepts are explored, with attention given to thermal storage systems coupled to Stirling and Brayton cycle power conversion devices. Sensible heat storage involving molten salt (NaOH), liquid sodium, and solid cordierite bricks are considered for 1500 F thermal storage systems. Latent heat storage with NaF-MgF2 phase change materials are explored in terms of passive, active, and direct contact designs. Comparisons are made of the effectiveness of thermal storage relative to redox, Na-S, Zn-Cl, and Zn-Br battery storage systems. Molten lead trickling down through a phase change eutectic, the NaF-MgF2, formed the direct contact system. Heat transport in all systems is effected through Inconel pipes. Using a cost goal of 120-150 mills/kWh as the controlling parameter, sensible heat systems with molten salts transport with either Stirling or Brayton engines, or latent heat systems with Stirling engines, and latent heat-Brayton engine with direct contact were favored in the analyses. Battery storage systems, however, offered the most flexibility of applications.

Comparison of advanced thermal and electrical storage for parabolic dish solar thermal power systems

NASA Technical Reports Server (NTRS)

Fujita, T.; Birur, G. C.; Schredder, J. M.; Bowyer, J. M.; Awaya, H. I.

1982-01-01

Parabolic dish solar concentrator cluster concepts are explored, with attention given to thermal storage systems coupled to Stirling and Brayton cycle power conversion devices. Sensible heat storage involving molten salt (NaOH), liquid sodium, and solid cordierite bricks are considered for 1500 F thermal storage systems. Latent heat storage with NaF-MgF2 phase change materials are explored in terms of passive, active, and direct contact designs. Comparisons are made of the effectiveness of thermal storage relative to redox, Na-S, Zn-Cl, and Zn-Br battery storage systems. Molten lead trickling down through a phase change eutectic, the NaF-MgF2, formed the direct contact system. Heat transport in all systems is effected through Inconel pipes. Using a cost goal of 120-150 mills/kWh as the controlling parameter, sensible heat systems with molten salts transport with either Stirling or Brayton engines, or latent heat systems with Stirling engines, and latent heat-Brayton engine with direct contact were favored in the analyses. Battery storage systems, however, offered the most flexibility of applications.

Characteristics of joining and hybrid composite forging of aluminum solid parts and galvanized steel sheets

NASA Astrophysics Data System (ADS)

Wesling, V.; Treutler, K.; Bick, T.; Stonis, M.; Langner, J.; Kriwall, M.

2018-06-01

In lightweight construction, light metals like aluminum are used in addition to high-strength steels. However, a welded joint of aluminum and steel leads to the precipitation of brittle, intermetallic phases and contact corrosion. Nevertheless, to use the advantages of this combination in terms of weight saving composite hybrid forging has been developed. In this process, an aluminum solid part and a steel sheet were formed in a single step and joined at the same time with zinc as brazing material. For this purpose, the zinc was applied by hot dipping on the aluminum in order to produce a connection via this layer in a forming process, under pressure and heat. Due to the formed intermediate layer of zinc, the formation of the Fe-Al intermetallic phases and the contact corrosion are excluded. By determining the mathematical relationships between joining parameters and the connection properties the strength of a specific joint geometry could be adjusted to reach the level of conventional joining techniques. In addition to the presentation of the joint properties, the influence of the joining process on the structure of the involved materials is also shown. Furthermore, the failure behavior under static tensile and shear stress will be shown.

Contact Dependence and Velocity Crossover in Friction between Microscopic Solid/Solid Contacts.

PubMed

McGraw, Joshua D; Niguès, Antoine; Chennevière, Alexis; Siria, Alessandro

2017-10-11

Friction at the nanoscale differs markedly from that between surfaces of macroscopic extent. Characteristically, the velocity dependence of friction between apparent solid/solid contacts can strongly deviate from the classically assumed velocity independence. Here, we show that a nondestructive friction between solid tips with radius on the scale of hundreds of nanometers and solid hydrophobic self-assembled monolayers has a strong velocity dependence. Specifically, using laterally oscillating quartz tuning forks, we observe a linear scaling in the velocity at the lowest accessed velocities, typically hundreds of micrometers per second, crossing over into a logarithmic velocity dependence. This crossover is consistent with a general multicontact friction model that includes thermally activated breaking of the contacts at subnanometric elongation. We find as well a strong dependence of the friction on the dimensions of the frictional probe.

Au-Ge MEAM potential fitted to the binary phase diagram

NASA Astrophysics Data System (ADS)

Wang, Yanming; Santana, Adriano; Cai, Wei

2017-02-01

We have developed a modified embedded atom method potential for the gold-germanium (Au-Ge) binary system that is fitted to the experimental binary phase diagram. The phase diagram is obtained from the common tangent construction of the free energy curves calculated by the adiabatic switching method. While maintaining the accuracy of the melting points of pure Au and Ge, this potential reproduces the eutectic temperature, eutectic composition and the solubility of Ge in solid Au, all in good agreement with the experimental values. To demonstrate the self-consistency of the potential, we performed benchmark molecular dynamics simulations of Ge crystal growth and etching in contact with a Au-Ge liquid alloy.

Aerodynamic method for obtaining the soil water retention curve

NASA Astrophysics Data System (ADS)

Alekseev, V. V.; Maksimov, I. I.

2013-07-01

A new method for the rapid plotting of the soil water retention curve (SWRC) has been proposed that considers the soil water as an environment limited by the soil solid phase on one side and by the soil air on the other side. Both contact surfaces have surface energies, which play the main role in water retention. The use of an idealized soil model with consideration for the nonequilibrium thermodynamic laws and the aerodynamic similarity principles allows us to estimate the volumetric specific surface areas of soils and, using the proposed pedotransfer function (PTF), to plot the SWRC. The volumetric specific surface area of the solid phase, the porosity, and the specific free surface energy at the water-air interface are used as the SWRC parameters. Devices for measuring the parameters are briefly described. The differences between the proposed PTF and the experimental data have been analyzed using the statistical processing of the data.

Molecular discriminators using single wall carbon nanotubes

NASA Astrophysics Data System (ADS)

Bhattacharyya, Tamoghna; Dasgupta, Anjan Kr; Ranjan Ray, Nihar; Sarkar, Sabyasachi

2012-09-01

The interaction between single wall carbon nanotubes (SWNTs) and amphiphilic molecules has been studied in a solid phase. SWNTs are allowed to interact with different amphiphilic probes (e.g. lipids) in a narrow capillary interface. Contact between strong hydrophobic and amphiphilic interfaces leads to a molecular restructuring of the lipids at the interface. The geometry of the diffusion front and the rate and the extent of diffusion of the interface are dependent on the structure of the lipid at the interface. Lecithin having a linear tail showed greater mobility of the interface as compared to a branched tail lipid like dipalmitoyl phosphatidylcholine, indicating the hydrophobic interaction between single wall carbon nanotube core and the hydrophobic tail of the lipid. Solid phase interactions between SWNT and lipids can thus become a very simple but efficient means of discriminating amphiphilic molecules in general and lipids in particular.

Structural and environmental dependence of superlow friction in ion vapour-deposited a-C : H : Si films for solid lubrication application

NASA Astrophysics Data System (ADS)

Chen, Xinchun; Kato, Takahisa; Kawaguchi, Masahiro; Nosaka, Masataka; Choi, Junho

2013-06-01

Understanding the tribochemical interaction of water molecules in humid environment with carbonaceous film surfaces, especially hydrophilic surface, is fundamental for applications in tribology and solid lubrication. This paper highlights some experimental evidence to elucidate the structural and environmental dependence of ultralow or even superlow friction in ion vapour-deposited a-C : H : Si films. The results indicate that both surface density of silicon hydroxyl group (Si-OH) and humidity level (RH) determine the frictional performance of a-C : H : Si films. Ultralow friction coefficient μ (˜0.01-0.055) is feasible in a wide range of RH. The dissociative formation of hydrophilic Si-OH surface and the following nanostructure of interfacial water molecules under contact pressure are the origin of ultralow friction for a-C : H : Si films in humid environment. The correlation between contact pressure and friction coefficient derived from Hertzian contact model is not valid in the present case. Under this nanoscale boundary lubrication, the friction coefficient tends to increase as the contact pressure increases. There even exists a contact pressure threshold for the transition from ultralow to superlow friction (μ ˜ 0.007). In comparison, when tribotested in dry N2, the observed superlow friction (μ ˜ 0.004) in the absence of water is correlated with the formation of a low shear strength tribolayer by wear-induced phase transformation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamel, R.S.; Landon, J.; Smith, D.S.

Nortriptyline derivatives prepared by reaction with fluorescein isothiocyanate or conjugation to N-acetyl-L-histidine were radioiodinated and the products purified with Sephadex LH-20 columns to obtain two novel nortriptyline radioligands. Antisera were raised in rabbits by immunization with nortriptyline conjugated to succinylated ovine albumin. By use of the iodinated fluorescein derivative we developd a liquid-phase second-antibody radioimmunoassay that gives results correlating closely (r = 0.98) with those by an established radioimmunoassay of similar specificity in the assay of apparent total amitriptyline and its metabolite nortriptyline in serum or plasma from patients being treated with these drugs. With the iodinated N-acetyl-L-histidin derivative wemore » developed a magnetizable solid-phase second-antibody radioimmunoassay. The cross reactivities of amitriptyline and nortriptyline could be made equal by performing the assay at pH 9.0, which makes it possible to measure true total active drug concentrations in patients receiving amitriptyline.« less

Device and method for enhanced collection and assay of chemicals with high surface area ceramic

DOEpatents

Addleman, Raymond S.; Li, Xiaohong Shari; Chouyyok, Wilaiwan; Cinson, Anthony D.; Bays, John T.; Wallace, Krys

2016-02-16

A method and device for enhanced capture of target analytes is disclosed. This invention relates to collection of chemicals for separations and analysis. More specifically, this invention relates to a solid phase microextraction (SPME) device having better capability for chemical collection and analysis. This includes better physical stability, capacity for chemical collection, flexible surface chemistry and high affinity for target analyte.

Coupling solid-phase extraction and enzyme-linked immunosorbent assay for ultratrace determination of herbicides in pristine water

USGS Publications Warehouse

Aga, D.S.; Thurman, E.M.

1993-01-01

Solid-phase extraction (SPE) and enzyme-linked immunosorbent assay (ELISA) were coupled for automated trace analysis of pristine water samples containing 2-chloro-4-ethylamino-6-isopropylamine-s-triazine (atrazine) and 2-chloro-2???,6???-diethyl-N-(methoxymethyl)acetanilide (alachlor). The isolation of the two herbicides on a C18-resin involved the selection of an elution solvent that both removes interfering substances and is compatible with ELISA. Ethyl acetate was selected as the elution solvent followed by a solvent exchange with methanol/water (20/80, % v/v). The SPE-ELISA method has a detection limit of 5.0 ng/L (5 ppt), >90% recovery, and a relative standard deviation of ??10%. The performance of a microtiter plate-based ELISA and a magnetic particle-based ELISA coupled to SPE was also evaluated. Although the sensitivity of the two ELISA methods was comparable, the precision using magnetic particles was improved considerably (??10% versus ??20%) because of the faster reaction kinetics provided by the magnetic particles. Finally, SPE-ELISA and isotope dilution gas chromatography/ mass spectrometry correlated well (correlation coefficient of 0.96) for lake-water samples. The SPE-ELISA method is simple and may have broader applications for the inexpensive automated analysis of other contaminants in water at trace levels.

Determination of alachlor and its sulfonic acid metabolite in water by solid-phase extraction and enzyme-linked immunosorbent assay

USGS Publications Warehouse

Aga, D.S.; Thurman, E.M.; Pomes, M.L.

1994-01-01

Solid-phase extraction (SPE) and enzyme-linked immunosorbent assay (ELISA) were combined for the trace analysis of the herbicide alachlor and its major soil metabolite, ethanesulfonic acid (ESA). The anti-alachlor antibody cross-reacted with ESA, which produced false-positive detections of alachlor in water samples by immunoassay screens. Alachlor and ESA were isolated from water by SPE on a C18 resin and eluted sequentially with ethyl acetate and methanol. Alachlor is soluble in ethyl acetate while the anionic ESA is not. Thus ESA remained adsorbed on the C18 resin and was eluted later with methanol. The combination of SPE with ELISA effectivety separated and quantified both alachlor and ESA using the same antibody for two ELISA methods. The general method may have applicability for the separation of other herbicides and their ionic metabolites. The SPE-ELISA method has a, detection limit of 0.01 ??g/L for alachlor and 0.05 ??g/L for ESA, with a precision of ?? 10%. Analyses of surface and ground water samples were confirmed by gas chromatography/mass spectrometry and high-performance liquid chromatography with photodiode-array detection. Results showed widespread occurrence of ESA in surface and ground water of the midwestern United States, with concentrations ranging from 10 ??g/L.

Electrochemical detection of Francisella tularensis genomic DNA using solid-phase recombinase polymerase amplification.

PubMed

del Río, Jonathan Sabaté; Yehia Adly, Nouran; Acero-Sánchez, Josep Lluis; Henry, Olivier Y F; O'Sullivan, Ciara K

2014-04-15

Solid-phase isothermal DNA amplification was performed exploiting the homology protein recombinase A (recA). The system was primarily tested on maleimide activated microtitre plates as a proof-of-concept and later translated to an electrochemical platform. In both cases, forward primer for Francisella tularensis holarctica genomic DNA was surface immobilised via a thiol or an amino moiety and then elongated during the recA mediated amplification, carried out in the presence of specific target sequence and reverse primers. The formation of the subsequent surface tethered amplicons was either colorimetrically or electrochemically monitored using a horseradish peroxidase (HRP)-labelled DNA secondary probe complementary to the elongated strand. The amplification time was optimised to amplify even low amounts of DNA copies in less than an hour at a constant temperature of 37°C, achieving a limit of detection of 1.3×10(-13) M (4×10(6) copies in 50 μL) for the colorimetric assay and 3.3×10(-14) M (2×10(5) copies in 10 μL) for the chronoamperometric assay. The system was demonstrated to be highly specific with negligible cross-reactivity with non-complementary targets or primers. © 2013 Elsevier B.V. All rights reserved.

General method to predict voltage-dependent ionic conduction in a solid electrolyte coating on electrodes

NASA Astrophysics Data System (ADS)

Pan, Jie; Cheng, Yang-Tse; Qi, Yue

2015-04-01

Understanding the ionic conduction in solid electrolytes in contact with electrodes is vitally important to many applications, such as lithium ion batteries. The problem is complex because both the internal properties of the materials (e.g., electronic structure) and the characteristics of the externally contacting phases (e.g., voltage of the electrode) affect defect formation and transport. In this paper, we developed a method based on density functional theory to study the physics of defects in a solid electrolyte in equilibrium with an external environment. This method was then applied to predict the ionic conduction in lithium fluoride (LiF), in contact with different electrodes which serve as reservoirs with adjustable Li chemical potential (μLi) for defect formation. LiF was chosen because it is a major component in the solid electrolyte interphase (SEI) formed on lithium ion battery electrodes. Seventeen possible native defects with their relevant charge states in LiF were investigated to determine the dominant defect types on various electrodes. The diffusion barrier of dominant defects was calculated by the climbed nudged elastic band method. The ionic conductivity was then obtained from the concentration and mobility of defects using the Nernst-Einstein relationship. Three regions for defect formation were identified as a function of μLi: (1) intrinsic, (2) transitional, and (3) p -type region. In the intrinsic region (high μLi, typical for LiF on the negative electrode), the main defects are Schottky pairs and in the p -type region (low μLi, typical for LiF on the positive electrode) are Li ion vacancies. The ionic conductivity is calculated to be approximately 10-31Scm-1 when LiF is in contact with a negative electrode but it can increase to 10-12Scm-1 on a positive electrode. This insight suggests that divalent cation (e.g., Mg2+) doping is necessary to improve Li ion transport through the engineered LiF coating, especially for LiF on negative electrodes. Our results provide an understanding of the influence of the environment on defect formation and demonstrate a linkage between defect concentration in a solid electrolyte and the voltage of the electrode.

Dewetting-mediated pattern formation in nanoparticle assemblies

NASA Astrophysics Data System (ADS)

Stannard, Andrew

2011-03-01

The deposition of nanoparticles from solution onto solid substrates is a diverse subfield of current nanoscience research. Complex physical and chemical processes underpin the self-assembly and self-organization of colloidal nanoparticles at two-phase (solid-liquid, liquid-air) interfaces and three-phase (solid-liquid-air) contact lines. This review discusses key recent advances made in the understanding of nonequilibrium dewetting processes of nanoparticle-containing solutions, detailing how such an apparently simple experimental system can give rise to such a strikingly varied palette of two-dimensional self-organized nanoparticle array morphologies. Patterns discussed include worm-like domains, cellular networks, microscale rings, and fractal-like fingering structures. There remain many unresolved issues regarding the role of the solvent dewetting dynamics in assembly processes of this type, with a significant focus on how dewetting can be coerced to produce nanoparticle arrays with desirable characteristics such as long-range order. In addition to these topics, methods developed to control nanofluid dewetting through routes such as confining the geometries of drying solutions, depositing onto pre-patterned heterogeneous substrates, and post-dewetting pattern evolution via local or global manipulation are covered.

Dewetting-mediated pattern formation in nanoparticle assemblies.

PubMed

Stannard, Andrew

2011-03-02

The deposition of nanoparticles from solution onto solid substrates is a diverse subfield of current nanoscience research. Complex physical and chemical processes underpin the self-assembly and self-organization of colloidal nanoparticles at two-phase (solid-liquid, liquid-air) interfaces and three-phase (solid-liquid-air) contact lines. This review discusses key recent advances made in the understanding of nonequilibrium dewetting processes of nanoparticle-containing solutions, detailing how such an apparently simple experimental system can give rise to such a strikingly varied palette of two-dimensional self-organized nanoparticle array morphologies. Patterns discussed include worm-like domains, cellular networks, microscale rings, and fractal-like fingering structures. There remain many unresolved issues regarding the role of the solvent dewetting dynamics in assembly processes of this type, with a significant focus on how dewetting can be coerced to produce nanoparticle arrays with desirable characteristics such as long-range order. In addition to these topics, methods developed to control nanofluid dewetting through routes such as confining the geometries of drying solutions, depositing onto pre-patterned heterogeneous substrates, and post-dewetting pattern evolution via local or global manipulation are covered.

Biomass drying in a pulsed fluidized bed without inert bed particles

DOE PAGES

Jia, Dening; Bi, Xiaotao; Lim, C. Jim; ...

2016-08-29

Batch drying was performed in the pulsed fluidized bed with various species of biomass particles as an indicator of gas–solid contact efficiency and mass transfer rate under different operating conditions including pulsation duty cycle and particle size distribution. The fluidization of cohesive biomass particles benefited from the shorter opening time of pulsed gas flow and increased peak pressure drop. The presence of fines enhanced gas–solid contact of large and irregular biomass particles, as well as the mass transfer efficiency. A drying model based on two-phase theory was proposed, from which effective diffusivity was calculated for various gas flow rates, temperaturemore » and pulsation frequency. Intricate relationship was discovered between pulsation frequency and effective diffusivity, as mass transfer was deeply connected with the hydrodynamics. Effective diffusivity was also found to be proportional to gas flow rate and drying temperature. In conclusion, operating near the natural frequency of the system also favored drying and mass transfer.« less

Polymer-functionalized nanoparticles for improving oil displacement

NASA Astrophysics Data System (ADS)

Fossati, Ana B.; Martins Alho, Miriam; Jacobo, Silvia E.

2018-03-01

This work focuses on the synthesis, functionalization, and characterization of magnetic nanoparticles to be used for improving the oil recovery in the oil exploitation industry. In this manuscript we explore three different types of hydrophobic/hydrophilic functionalization through a silanized particle: with styrene, with acrylic acid and with a copolymer of styrene and maleic acid. Further application of such nanoparticles dispersions (nanofluid) are discussed as the wetting and spreading behaviour of liquids on the solid surfaces change if the wettability of solid surface is altered. In order to investigate the influence of wettability alternation on enhancing oil recovery after nanofluid treatment, flushing oil experiment and contact angle measurement were conducted in our laboratory. The results indicated that nanofluid can produce a better flushing efficiency compared with brine solution, and the contact angles of oil phase increased from 13° to 37° after nanofluid treatment (0.005% w/w). We focus on the synthesis of magnetic iron oxide nanoparticles considering recovering possibility.

Electroplating of nanostructured polyaniline-polypyrrole composite coating in a stainless-steel tube for on-line in-tube solid phase microextraction.

PubMed

Asiabi, Hamid; Yamini, Yadollah; Seidi, Shahram; Esrafili, Ali; Rezaei, Fatemeh

2015-06-05

In this work, a novel and efficient on-line in-tube solid phase microextraction method followed by high performance liquid chromatography was developed for preconcentration and determination of trace amounts of parabens. A nanostructured polyaniline-polypyrrole composite was electrochemically deposited on the inner surface of a stainless steel tube and used as the extraction phase. Several important factors that influence the extraction efficiency, including type of solid-phase coating, extraction and desorption times, flow rates of the sample solution and eluent, pH, and ionic strength of the sample solution were investigated and optimized. Under the optimal conditions, the limits of detection were in the range of 0.02-0.04 μg L(-1). This method showed good linearity for parabens in the range of 0.07-50 μg L(-1), with coefficients of determination better than 0.998. The intra- and inter-assay precisions (RSD%, n=3) were in the range of 5.9-7.0% and 4.4-5.7% at three concentration levels of 2, 10, and 20 μg L(-1), respectively. The extraction recovery values for the spiked samples were in the acceptable range of 80.3-90.2%. The validated method was successfully applied for analysis of methyl-, ethyl-, and propyl parabens in some water, milk, and juice samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Validated high-performance liquid chromatographic method utilizing solid-phase extraction for the simultaneous determination of naringenin and hesperetin in human plasma.

PubMed

Kanaze, Feras Imad; Kokkalou, Eugene; Georgarakis, Manolis; Niopas, Ioannis

2004-03-05

Naringenin and hesperetin, the aglycones of the flavanone glucosides naringin and hesperidin occur naturally in citrus fruits. They exert a variety of pharmacological effects such as antioxidant, blood lipid-lowering, anticarcinogenic and inhibit selected cytochrome P-450 enzymes resulting in drug interactions. A specific, sensitive, precise, and accurate solid-phase extraction high-performance liquid chromatographic (HPLC) assay for the simultaneous determination of naringenin and hesperetin in human plasma was developed and validated. After addition of 7-ethoxycoumarin as internal standard, plasma samples were incubated with beta-glucuronidase/sulphatase, and the analytes were isolated from plasma by solid-phase extraction using C(18) cartridges and separated on a C(8) reversed phase column with methanol/water/acetic acid (40:58:2, v/v/v) as the eluent at 45 degrees C. The method was linear in the 10-300 ng/ml concentration range for both naringenin and hesperetin (r>0.999). Recovery for naringenin, hesperetin and internal standard was greater than 76.7%. Intra- and inter-day precision for naringenin ranged from 1.4 to 4.2% and from 1.9 to 5.2%, respectively, and for hesperetin ranged from 1.3 to 4.1% and from 1.7 to 5.1%, respectively. Accuracy was better than 91.5 and 91.3% for naringenin and hesperetin, respectively.

Solid-Phase Synthesis of RNA Analogs Containing Phosphorodithioate Linkages.

PubMed

Yang, Xianbin

2017-09-18

The oligoribonucleotide phosphorodithioate (PS2-RNA) modification uses two sulfur atoms to replace two non-bridging oxygen atoms at an internucleotide phosphorodiester backbone linkage. Like a natural phosphodiester RNA backbone linkage, a PS2-modified backbone linkage is achiral at phosphorus. PS2-RNAs are highly stable to nucleases and several in vitro assays have demonstrated their biological activity. For example, PS2-RNAs silenced mRNA in vitro and bound to protein targets in the form of PS2-aptamers (thioaptamers). Thus, the interest in and promise of PS2-RNAs has drawn attention to synthesizing, isolating, and characterizing these compounds. RNA-thiophosphoramidite monomers are commercially available from AM Biotechnologies and this unit describes an effective methodology for solid-phase synthesis, deprotection, and purification of RNAs having PS2 internucleotide linkages. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

Extraction of domoic acid from seawater and urine using a resin based on 2-(trifluoromethyl)acrylic acid.

PubMed

Piletska, Elena V; Villoslada, Fernando Navarro; Chianella, Iva; Bossi, Alessandra; Karim, Kal; Whitcombe, Michael J; Piletsky, Sergey A; Doucette, Gregory J; Ramsdell, John S

2008-03-03

A new solid-phase extraction (SPE) matrix with high affinity for the neurotoxin domoic acid (DA) was designed and tested. A computational modelling study led to the selection of 2-(trifluoromethyl)acrylic acid (TFMAA) as a functional monomer capable of imparting affinity towards domoic acid. Polymeric adsorbents containing TFMAA were synthesised and tested in high ionic strength solutions such as urine and seawater. The TFMAA-based polymers demonstrated excellent performance in solid-phase extraction of domoic acid, retaining the toxin while salts and other interfering compounds such as aspartic and glutamic acids were removed by washing and selective elution. It was shown that the TFMAA-based polymer provided the level of purification of domoic acid from urine and seawater acceptable for its quantification by high performance liquid chromatography-mass spectrometry (HPLC-MS) and enzyme-linked immunosorbent assay (ELISA) without any additional pre-concentration and purification steps.

Numerical evaluation of the surface deformation of elastic solids subjected to a hertzian contact stress

NASA Technical Reports Server (NTRS)

Hamrock, B. J.; Dowson, D.

1974-01-01

The elastic deformation of two ellipsoidal solids in contact and subjected to Hertzian stress distribution was evaluated numerically as part of a general study of the elastic deformation of such solids in elastohydrodynamic contacts. In the analysis the contact zone was divided into equal rectangular areas, and it was assumed that a uniform pressure is applied over each rectangular area. The influence of the size of the rectangular area upon accuracy was also studied. The results indicate the distance from the center of the contact at which elastic deformation becomes insignificant.

A double medium model for diffusion in fluid-bearing rock

NASA Astrophysics Data System (ADS)

Wang, H. F.

1993-09-01

The concept of a double porosity medium to model fluid flow in fractured rock has been applied to model diffusion in rock containing a small amount of a continuous fluid phase that surrounds small volume elements of the solid matrix. The model quantifies the relative role of diffusion in the fluid and solid phases of the rock. The fluid is the fast diffusion path, but the solid contains the volumetrically significant amount of the diffusing species. The double medium model consists of two coupled differential equations. One equation is the diffusion equation for the fluid concentration; it contains a source term for change in the average concentration of the diffusing species in the solid matrix. The second equation represents the assumption that the change in average concentration in a solid element is proportional to the difference between the average concentration in the solid and the concentration in the fluid times the solid-fluid partition coefficient. The double medium model is shown to apply to laboratory data on iron diffusion in fluid-bearing dunite and to measured oxygen isotope ratios at marble-metagranite contacts. In both examples, concentration profiles are calculated for diffusion taking place at constant temperature, where a boundary value changes suddenly and is subsequently held constant. Knowledge of solid diffusivities can set a lower bound to the length of time over which diffusion occurs, but only the product of effective fluid diffusivity and time is constrained for times longer than the characteristic solid diffusion time. The double medium results approach a local, grain-scale equilibrium model for times that are large relative to the time constant for solid diffusion.

Hydride Generation for Headspace Solid-Phase Extraction with CdTe Quantum Dots Immobilized on Paper for Sensitive Visual Detection of Selenium.

PubMed

Huang, Ke; Xu, Kailai; Zhu, Wei; Yang, Lu; Hou, Xiandeng; Zheng, Chengbin

2016-01-05

A low-cost, simple, and highly selective analytical method was developed for sensitive visual detection of selenium in human urine both outdoors and at home, by coupling hydride generation with headspace solid-phase extraction using quantum dots (QDs) immobilized on paper. The visible fluorescence from the CdTe QDs immobilized on paper was quenched by H2Se from hydride generation reaction and headspace solid-phase extraction. The potential mechanism was investigated by using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) as well as Density Functional Theory (DFT). Potential interferences from coexisting ions, particularly Ag(+), Cu(2+), and Zn(2+), were eliminated. The selectivity was significantly increased because the selenium hydride was effectively separated from sample matrices by hydride generation. Moreover, due to the high sampling efficiency of hydride generation and headspace solid phase extraction, the sensitivity and the limit of detection (LOD) were significantly improved compared to conventional methods. A LOD of 0.1 μg L(-1) and a relative standard deviation (RSD, n = 7) of 2.4% at a concentration of 20 μg L(-1) were obtained when using a commercial spectrofluorometer as the detector. Furthermore, a visual assay based on the proposed method was developed for the detection of Se, 5 μg L(-1) of selenium in urine can be discriminated from the blank solution with the naked eye. The proposed method was validated by analysis of certified reference materials and human urine samples with satisfactory results.

Promiscuous interactions and protein disaggregases determine the material state of stress-inducible RNP granules

PubMed Central

Kroschwald, Sonja; Maharana, Shovamayee; Mateju, Daniel; Malinovska, Liliana; Nüske, Elisabeth; Poser, Ina; Richter, Doris; Alberti, Simon

2015-01-01

RNA-protein (RNP) granules have been proposed to assemble by forming solid RNA/protein aggregates or through phase separation into a liquid RNA/protein phase. Which model describes RNP granules in living cells is still unclear. In this study, we analyze P bodies in budding yeast and find that they have liquid-like properties. Surprisingly, yeast stress granules adopt a different material state, which is reminiscent of solid protein aggregates and controlled by protein disaggregases. By using an assay to ectopically nucleate RNP granules, we further establish that RNP granule formation does not depend on amyloid-like aggregation but rather involves many promiscuous interactions. Finally, we show that stress granules have different properties in mammalian cells, where they show liquid-like behavior. Thus, we propose that the material state of RNP granules is flexible and that the solid state of yeast stress granules is an adaptation to extreme environments, made possible by the presence of a powerful disaggregation machine. DOI: http://dx.doi.org/10.7554/eLife.06807.001 PMID:26238190

Resolved granular debris-flow simulations with a coupled SPH-DCDEM model

NASA Astrophysics Data System (ADS)

Birjukovs Canelas, Ricardo; Domínguez, José M.; Crespo, Alejandro J. C.; Gómez-Gesteira, Moncho; Ferreira, Rui M. L.

2016-04-01

Debris flows represent some of the most relevant phenomena in geomorphological events. Due to the potential destructiveness of such flows, they are the target of a vast amount of research (Takahashi, 2007 and references therein). A complete description of the internal processes of a debris-flow is however still an elusive achievement, explained by the difficulty of accurately measuring important quantities in these flows and developing a comprehensive, generalized theoretical framework capable of describing them. This work addresses the need for a numerical model applicable to granular-fluid mixtures featuring high spatial and temporal resolution, thus capable of resolving the motion of individual particles, including all interparticle contacts. This corresponds to a brute-force approach: by applying simple interaction laws at local scales the macro-scale properties of the flow should be recovered by upscaling. This methodology effectively bypasses the complexity of modelling the intermediate scales by resolving them directly. The only caveat is the need of high performance computing, a demanding but engaging research challenge. The DualSPHysics meshless numerical implementation, based on Smoothed Particle Hydrodynamics (SPH), is expanded with a Distributed Contact Discrete Element Method (DCDEM) in order to explicitly solve the fluid and the solid phase. The model numerically solves the Navier-Stokes and continuity equations for the liquid phase and Newton's motion equations for solid bodies. The interactions between solids are modelled with classical DEM approaches (Kruggel-Emden et al, 2007). Among other validation tests, an experimental set-up for stony debris flows in a slit check dam is reproduced numerically, where solid material is introduced trough a hopper assuring a constant solid discharge for the considered time interval. With each sediment particle undergoing tens of possible contacts, several thousand time-evolving contacts are efficiently treated. Fully periodic boundary conditions allow for the recirculation of the material. The results, comprising mainly of retention curves, are in good agreement with the measurements, correctly reproducing the changes in efficiency with slit spacing and effective density. Ackownledgements: Project RECI/ECM-HID/0371/2012, funded by the Portuguese Foundation for Science and Technology (FCT), has partially supported this work. It was also partially funded by Xunta de Galicia under project Programa de Consolidacion e Estructuracion de Unidades de Investigacion Competitivas (Grupos de Referencia Competitiva), financed by European Regional Development Fund (FEDER) and by Ministerio de Economia y Competitividad under de Project BIA2012-38676-C03-03. References Takahashi, T. Debris Flow, Mechanics, Prediction and Countermeasures. Taylor and Francis, 2007 Kruggel-Emden, H.; Simsek, E.; Rickelt, S.; Wirtz, S. & Scherer, V. Review and extension of normal force models for the Discrete Element Method. Powder Technology , 2007, 171, 157 - 173

Complete oxidation of solid phase sulfides by manganese and bacteria in anoxic marine sediments

NASA Astrophysics Data System (ADS)

Aller, Robert C.; Rude, Peter D.

1988-03-01

During the physical or biological reworking of surficial marine sediments, metal oxides are often brought into contact with both solid and dissolved sulfides. Experiments simulating these mixing processes demonstrate that in natural sediments Mn-oxides can completely oxidize solid phase sulfides to SO 4- under anoxic conditions. The major source of sulfur is probably acid volatile sulfide. Minerals containing Mn +4 are apparently more effective than Mn +3 in driving the oxidation. There is slight or no evidence for complete sulfide oxidation by Fe-oxides under similar conditions. The reaction is inhibited by DNP (dinitrophenol) and azide, implying biological mediation by a group of chemolithotrophic bacteria such as the thiobacilli, having a well-organized cytochrome system, oxidative phosphorylation coupled with sulfide oxidation, and possibly aulolrophic CO 2 fixation. Lack of sensitivity to chlorate suggests that a No 3- reductase complex is not involved. Because of metal reduction and the overall stoichiometry of reaction, this sulfide oxidation causes a rise in pH in contrast to oxidation by O 2. Alkalinity is also simultaneously depeleted by Mn, Ca carbonate precipitation. Both manganoan kutnahorite and manganoan calcite are observed to form rapidly (days) during Mn reduction. The oxidation of sulfides by Mn-oxides is likely to be important, but highly variable, in organic-rich shelf sediments and environments such as hydrothermal vents where sulfidic plumes contact oxidized metals. A substantial Proportion of sedimentary sulfide may be oxidized and Mn reduced by this pathway, particularly in bioturbated sediments. The relative roles of lithotrophic (S) and heterotrophic (C) Mn-reduction in marine sediments are presently unknown.

Spectrophotometric determination of basic fuchsin from various water samples after vortex assisted solid phase extraction using reduced graphene oxide as an adsorbent.

PubMed

Tokalıoğlu, Şerife; Yavuz, Emre; Aslantaş, Ayşe; Şahan, Halil; Taşkın, Ferhat; Patat, Şaban

2015-01-01

In this study, a fast and simple vortex assisted solid phase extraction method was developed for the separation/preconcentration of basic fuchsin in various water samples. The determination of basic fuchsin was carried out at a wavelength of 554 nm by spectrophotometry. Reduced graphene oxide which was used as a solid phase extractor was synthesized and characterized by X-ray diffraction, scanning electron microscopy and the Brunauer, Emmett and Teller. The optimum conditions are as follows: pH 2, contact times for adsorption and elution of 30 s and 90 s, respectively, 10 mg adsorbent, and eluent (ethanol) volume of 1 mL. The effects of some interfering ions and dyes were investigated. The method was linear in the concentration range of 50-250 μg L(-1). The adsorption capacity was 34.1 mg g(-1). The preconcentration factor, limit of detection and precision (RSD, %) of the method were found to be 400, 0.07 μg L(-1) and 1.2%, respectively. The described method was validated by analyzing basic fuchsin spiked certified reference material (SPS-WW1 Batch 114-Wastewater) and spiked real water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

A rapid and sensitive assay of perfluorocarboxylic acids in aqueous matrices by headspace solid phase microextraction-gas chromatography-triple quadrupole mass spectrometry.

PubMed

Monteleone, Marcello; Naccarato, Attilio; Sindona, Giovanni; Tagarelli, Antonio

2012-08-17

The work aims at developing a rapid and sensitive method for the quantification of perfluorocarboxylic acids in aqueous matrices. The proposed analytical approach is based on the use of solid phase microextraction in headspace mode after a fast derivatization of the carboxylate function by propylchloroformate/propanol mixture. Several fibers were evaluated and the optimization of the parameters affecting the SPME process was carried out using a central composite design. The optimum working conditions in terms of response values were achieved by performing analysis with CAR/PDMS fiber at room temperature, without addition of NaCl, with a sample volume of 6 ml and an extraction time of 10 min. Assay of PFCAs was performed by using a gas chromatography-triple quadrupole mass spectrometry (GC-QqQ MS) system in negative chemical ionization mode with ammonia as reagent gas. An overall evaluation of all analytical parameters shows that the proposed method provides satisfactory results. In particular, the observed accuracies, ranging from 84.4% to 116.8%, and the RSD values in the range 0.4% and 14.5% confirm the effectiveness of the developed protocol in the assay of PFCAs content in aqueous matrices. Moreover, LOD and LOQ values ranging from 0.08 to 6.6 ng l(-1) and from 0.17 to 14.3 ng l(-1), respectively, can be considered very satisfactory. None of the compounds were detected in six samples of river collected in Calabria. Copyright © 2012 Elsevier B.V. All rights reserved.

Assessing the toxicity of sediments using the medaka embryo-larval assay and 2 other bioassays.

PubMed

Barhoumi, Badreddine; Clérandeau, Christelle; Landi, Laure; Pichon, Anaïk; Le Bihanic, Florane; Poirier, Dominique; Anschutz, Pierre; Budzinski, Hélène; Driss, Mohamed Ridha; Cachot, Jérôme

2016-09-01

Sediments are sinks for aquatic pollutants, and analyzing toxicity in such complex matrices is still challenging. To evaluate the toxicity of bioavailable pollutants accumulated in sediments from the Bizerte lagoon (Tunisia), a novel assay, the medaka embryo-larval assay by sediment contact, was applied. Japanese medaka (Oryzias latipes) embryos were incubated in direct contact with sediment samples up to hatching. Lethal and sublethal adverse effects were recorded in embryos and larvae up to 20 d postfertilization. Results from medaka embryo-larval assay were compared with cytotoxicity (Microtox®), genotoxicity (SOS chromotest), and pollutant content of sediments. The results highlight differences in the contamination profile and toxicity pattern between the different studied sediments. A significant correlation was shown between medaka embryo-larval assay by sediment contact and SOS chromotest responses and concentrations of most organic pollutants studied. No correlation was shown between pollutant levels and Microtox. According to the number of sediment samples detected as toxic, medaka embryo-larval assay by sediment contact was more sensitive than Microtox, which in turn was more sensitive than the SOS chromotest; and medaka embryo-larval assay by sediment contact allowed sediment toxicity assessment of moderately polluted sediments without pollutant extraction and using an ecologically realistic exposure scenario. Although medaka embryo-larval assay by sediment contact should be tested on a larger sample set, the results show that it is sensitive and convenient enough to monitor the toxicity of natural sediments. Environ Toxicol Chem 2016;35:2270-2280. © 2016 SETAC. © 2016 SETAC.

Molecular Dynamics Study of Thermally Augmented Nanodroplet Motion on Chemical Energy Induced Wettability Gradient Surfaces.

PubMed

Chakraborty, Monojit; Chowdhury, Anamika; Bhusan, Richa; DasGupta, Sunando

2015-10-20

Droplet motion on a surface with chemical energy induced wettability gradient has been simulated using molecular dynamics (MD) simulation to highlight the underlying physics of molecular movement near the solid-liquid interface including the contact line friction. The simulations mimic experiments in a comprehensive manner wherein microsized droplets are propelled by the surface wettability gradient against forces opposed to motion. The liquid-wall Lennard-Jones interaction parameter and the substrate temperature are varied to explore their effects on the three-phase contact line friction coefficient. The contact line friction is observed to be a strong function of temperature at atomistic scales, confirming their experimentally observed inverse functionality. Additionally, the MD simulation results are successfully compared with those from an analytical model for self-propelled droplet motion on gradient surfaces.

Separation by solvent extraction

DOEpatents

Holt, Jr., Charles H.

1976-04-06

17. A process for separating fission product values from uranium and plutonium values contained in an aqueous solution, comprising adding an oxidizing agent to said solution to secure uranium and plutonium in their hexavalent state; contacting said aqueous solution with a substantially water-immiscible organic solvent while agitating and maintaining the temperature at from -1.degree. to -2.degree. C. until the major part of the water present is frozen; continuously separating a solid ice phase as it is formed; separating a remaining aqueous liquid phase containing fission product values and a solvent phase containing plutonium and uranium values from each other; melting at least the last obtained part of said ice phase and adding it to said separated liquid phase; and treating the resulting liquid with a new supply of solvent whereby it is practically depleted of uranium and plutonium.

New Technology for Oil/Water Emulsion Treatment: Phases I and II

DTIC Science & Technology

1998-05-15

m.(Aŕ) Emulsions have long been of practical interest because of their extensive everyday applications. Emulsions are used in foods ( milk and...separating cream from milk . Valve-discharge centrifuges periodically discharge accumulated solids. Split-bowl centrifuges have a bowl that allows...fresh air. Call a physician. RVF CONTACT: Flush with water for 15 minutes. Call a physician. Wash thSroSghly with soap and rinse with water. Call

The EpiOcular Eye Irritation Test (EIT) for hazard identification and labelling of eye irritating chemicals: protocol optimisation for solid materials and the results after extended shipment.

PubMed

Kaluzhny, Yulia; Kandárová, Helena; Handa, Yuki; DeLuca, Jane; Truong, Thoa; Hunter, Amy; Kearney, Paul; d'Argembeau-Thornton, Laurence; Klausner, Mitchell

2015-05-01

The 7th Amendment to the EU Cosmetics Directive and the EU REACH Regulation have reinforced the need for in vitro ocular test methods. Validated in vitro ocular toxicity tests that can predict the human response to chemicals, cosmetics and other consumer products are required for the safety assessment of materials that intentionally, or inadvertently, come into contact with the eye. The EpiOcular Eye Irritation Test (EIT), which uses the normal human cell-based EpiOcular™ tissue model, was developed to address this need. The EpiOcular-EIT is able to discriminate, with high sensitivity and accuracy, between ocular irritant/corrosive materials and those that require no labelling. Although the original EpiOcular-EIT protocol was successfully pre-validated in an international, multicentre study sponsored by COLIPA (the predecessor to Cosmetics Europe), data from two larger studies (the EURL ECVAM-COLIPA validation study and an independent in-house validation at BASF SE) resulted in a sensitivity for the protocol for solids that was below the acceptance criteria set by the Validation Management Group (VMG) for eye irritation, and indicated the need for improvement of the assay's sensitivity for solids. By increasing the exposure time for solid materials from 90 minutes to 6 hours, the optimised EpiOcular-EIT protocol achieved 100% sensitivity, 68.4% specificity and 84.6% accuracy, thereby meeting all the acceptance criteria set by the VMG. In addition, to satisfy the needs of Japan and the Pacific region, the EpiOcular-EIT method was evaluated for its performance after extended shipment and storage of the tissues (4-5 days), and it was confirmed that the assay performs with similar levels of sensitivity, specificity and reproducibility in these circumstances. 2015 FRAME.

Reversible temperature regulation of electrical and thermal conductivity using liquid–solid phase transitions

PubMed Central

Zheng, Ruiting; Gao, Jinwei; Wang, Jianjian; Chen, Gang

2011-01-01

Reversible temperature tuning of electrical and thermal conductivities of materials is of interest for many applications, including seasonal regulation of building temperature, thermal storage and sensors. Here we introduce a general strategy to achieve large contrasts in electrical and thermal conductivities using first-order phase transitions in percolated composite materials. Internal stress generated during a phase transition modulates the electrical and thermal contact resistances, leading to large contrasts in the electrical and thermal conductivities at the phase transition temperature. With graphite/hexadecane suspensions, the electrical conductivity changes 2 orders of magnitude and the thermal conductivity varies up to 3.2 times near 18 °C. The generality of the approach is also demonstrated in other materials such as graphite/water and carbon nanotube/hexadecane suspensions. PMID:21505445

Reversible temperature regulation of electrical and thermal conductivity using liquid-solid phase transitions.

PubMed

Zheng, Ruiting; Gao, Jinwei; Wang, Jianjian; Chen, Gang

2011-01-01

Reversible temperature tuning of electrical and thermal conductivities of materials is of interest for many applications, including seasonal regulation of building temperature, thermal storage and sensors. Here we introduce a general strategy to achieve large contrasts in electrical and thermal conductivities using first-order phase transitions in percolated composite materials. Internal stress generated during a phase transition modulates the electrical and thermal contact resistances, leading to large contrasts in the electrical and thermal conductivities at the phase transition temperature. With graphite/hexadecane suspensions, the electrical conductivity changes 2 orders of magnitude and the thermal conductivity varies up to 3.2 times near 18 °C. The generality of the approach is also demonstrated in other materials such as graphite/water and carbon nanotube/hexadecane suspensions.

Quantitative analysis of aldehydes in canned vegetables using static headspace-gas chromatography-mass spectrometry.

PubMed

Serrano, María; Gallego, Mercedes; Silva, Manuel

2017-11-17

Volatile aldehydes appear in canned vegetables as constituents and some of them can also be present as disinfection by-products (DBPs) because of the contact between vegetables and treated water. This paper describes two static headspace-gas chromatography-mass spectrometry (SHS-GC-MS) methods to determine 15 aldehydes in both the solid and the liquid phases of canned vegetables. The treatment for both phases of samples was carried out simultaneously into an SHS unit, including the leaching of the aldehydes (from the vegetable), their derivatization and volatilization of the oximes formed. Detection limits were obtained within the range of 15-400μg/kg and 3-40μg/L for aldehydes in the solid and the liquid phases of the food, respectively. The relative standard deviation was lower than 7% -for the whole array of the target analytes-, the trueness evaluated by recovery experiments provided %recoveries between 89 and 99% and short- and long-term stability studies indicated there was no significant variation in relative peak areas of all aldehydes in both phases of canned vegetables after their storing at 4°C for two weeks. The study of the origin of the 15 aldehydes detected between both phases of canned vegetables showed that: i) the presence of 13 aldehydes -at average concentrations of 2.2-39μg/kg and 0.25-71μg/L for the solid and the liquid phases, respectively- is because they are natural constituents of vegetables; and ii) the presence of glyoxal and methylglyoxal -which are mainly found in the liquid phase (average values, 1.4-4.1μg/L)- is ascribed to the use of treated water, thereby being DBPs. Copyright © 2017 Elsevier B.V. All rights reserved.

The role of the micro environment on the tribological behavior of materials

NASA Technical Reports Server (NTRS)

Buckley, D. H.

1980-01-01

The paper reviews studies of the role of the microenvironment in the adhesion, friction, and wear behavior of materials in solid-state contact. The microenvironment is defined as the environment on the surface of solids in solid-state contact. Properties of the environment are discussed which exert an influence on the adhesion, friction, wear, and lubrication of materials in contact. The effect of the environment on lubricants and their properties is considered with respect to the interaction of lubricants with material surfaces in contact; the effect on the ability of lubricants to provide protective surface films is also considered. It is concluded that naturally occurring oxides are probably the best available natural solid-film lubricants.

Long-term behaviour of solid oxide fuel cell interconnect materials in contact with Ni-mesh during exposure in simulated anode gas at 700 and 800 °C

NASA Astrophysics Data System (ADS)

Garcia-Fresnillo, L.; Shemet, V.; Chyrkin, A.; de Haart, L. G. J.; Quadakkers, W. J.

2014-12-01

In the present study the long-term behaviour of two ferritic steels, Crofer 22 APU and Crofer 22H, in contact with a Ni-mesh during exposure in simulated anode gas, Ar-4%H2-2%H2O, at 700 and 800 °C for exposure times up to 3000 h was investigated. Ni diffusion from the Ni-mesh into the steel resulted in the formation of an austenitic zone whereas diffusion of iron and chromium from the steel into the Ni-mesh resulted in the formation of chromia base oxides in the Ni-mesh. Depending on the chemical composition of the steel, the temperature and the exposure time, interdiffusion processes between ferritic steel and Ni-mesh also resulted in σ-phase formation at the austenite-ferrite interface and in Laves-phase dissolution in the austenitic zone. The extent and morphology of the σ-phase formation are discussed on the basis of thermodynamic considerations, including reaction paths in the ternary alloy system Fe-Ni-Cr.

Composite materials for thermal energy storage

NASA Astrophysics Data System (ADS)

Benson, D. K.; Burrows, R. W.; Shinton, Y. D.

1985-01-01

A composite material for thermal energy storage based upon polyhydric alcohols, such as pentaerythritol, trimethylol ethane (also known as pentaglycerine), neopentyl glycol and related compounds including trimethylol propane, monoaminopentaerythritol, diamino-pentaerythritol and tris(hydroxymethyl)acetic acid, separately or in combinations, which provide reversible heat storage through crystalline phase transformations are discussed. These PCM's do not become liquid during use and are in contact with at least one material selected from the group consisting of metals, carbon, siliceous, plastic, cellulosic, natural fiber, artificial fiber, concrete, gypsum, porous rock, and mixtures thereof. Particulate additions such as aluminum or graphite powders, as well as metal and carbon fibers can also be incorporated therein. Particulate and/or fibrous additions can be introduced into molten phase change materials which can then be cast into various shapes. After the phase change materials have solidified, the additions will remain dispersed throughout the matrix of the cast solid. The polyol is in contact with at least one material selected from the group consisting of metals, carbon, siliceous, plastic, cellulosic, natural fiber, artificial fiber, concrete, gypsum, and mixtures thereof.

Composite materials for thermal energy storage

DOEpatents

Benson, D.K.; Burrows, R.W.; Shinton, Y.D.

1985-01-04

A composite material for thermal energy storage based upon polyhydric alcohols, such as pentaerythritol, trimethylol ethane (also known as pentaglycerine), neopentyl glycol and related compounds including trimethylol propane, monoaminopentaerythritol, diamino-pentaerythritol and tris(hydroxymethyl)acetic acid, separately or in combinations, which provide reversible heat storage through crystalline phase transformations. These PCM's do not become liquid during use and are in contact with at least one material selected from the group consisting of metals, carbon, siliceous, plastic, cellulosic, natural fiber, artificial fiber, concrete, gypsum, porous rock, and mixtures thereof. Particulate additions such as aluminum or graphite powders, as well as metal and carbon fibers can also be incorporated therein. Particulate and/or fibrous additions can be introduced into molten phase change materials which can then be cast into various shapes. After the phase change materials have solidified, the additions will remain dispersed throughout the matrix of the cast solid. The polyol is in contact with at least one material selected from the group consisting of metals, carbon, siliceous, plastic, cellulosic, natural fiber, artificial fiber, concrete, gypsum, and mixtures thereof.

77 FR 11536 - Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-27

... Categorization of Chemicals Causing Allergic Contact Dermatitis: Availability of Federal Agency Responses AGENCY... lymph node assay (LLNA) for potency categorization of chemicals causing allergic contact dermatitis (ACD... Local Lymph Node Assay for Potency Categorization of Chemicals Causing Allergic Contact Dermatitis in...

Gold catalyzed nickel disilicide formation: a new solid-liquid-solid phase growth mechanism.

PubMed

Tang, Wei; Picraux, S Tom; Huang, Jian Yu; Liu, Xiaohua; Tu, K N; Dayeh, Shadi A

2013-01-01

The vapor-liquid-solid (VLS) mechanism is the predominate growth mechanism for semiconductor nanowires (NWs). We report here a new solid-liquid-solid (SLS) growth mechanism of a silicide phase in Si NWs using in situ transmission electron microcopy (TEM). The new SLS mechanism is analogous to the VLS one in relying on a liquid-mediating growth seed, but it is fundamentally different in terms of nucleation and mass transport. In SLS growth of Ni disilicide, the Ni atoms are supplied from remote Ni particles by interstitial diffusion through a Si NW to the pre-existing Au-Si liquid alloy drop at the tip of the NW. Upon supersaturation of both Ni and Si in Au, an octahedral nucleus of Ni disilicide (NiSi2) forms at the center of the Au liquid alloy, which thereafter sweeps through the Si NW and transforms Si into NiSi2. The dissolution of Si by the Au alloy liquid mediating layer proceeds with contact angle oscillation at the triple point where Si, oxide of Si, and the Au alloy meet, whereas NiSi2 is grown from the liquid mediating layer in an atomic stepwise manner. By using in situ quenching experiments, we are able to measure the solubility of Ni and Si in the Au-Ni-Si ternary alloy. The Au-catalyzed mechanism can lower the formation temperature of NiSi2 by 100 °C compared with an all solid state reaction.

Development of SPME-LC-MS method for screening of eight beta-blockers and bronchodilators in plasma and urine samples.

PubMed

Goryński, Krzysztof; Kiedrowicz, Alicja; Bojko, Barbara

2016-08-05

The current work describes the development and validation of a simple, efficient, and fast method using solid phase microextraction coupled to liquid chromatography-tandem mass spectrometry (SPME-LC-MS/MS) for the concomitant measurement of eight beta-blockers and bronchodilators in plasma and urine. The presented assay enables quantitative determination of acebutolol, atenolol, fenoterol, nadolol, pindolol, procaterol, sotalol, and timolol. In this work, samples were prepared on a high-throughput platform using the 96-well plate format of the thin film solid phase microextraction (TFME) system, and a biocompatible extraction phase made of hydrophilic-lipophilic balance particles. Analytes were separated on a pentafluorophenyl column (100mm×2.1mm, 3μm) by gradient elution using an UPLC Nexera coupled with an LCMS-8060 mass spectrometer. The mobile phase consisted of water-acetonitrile (0.1% formic acid) at a flow rate of 0.4mLmin(-1). The linearity of the method was checked within therapeutic blood-plasma concentrations, and shown to adequately reflect typically expected concentrations of future study samples. Post-extraction addition experiments showed that the matrix effect ranged in plasma from 98% for procaterol to 115% for nadolol, and in urine, from 85% for nadolol and pindolol to 119% for atenolol. The method was successfully validated using Food and Drug Administration (FDA) guidelines, and met all acceptance criteria for bioanalytical assays at five concentration levels for all selected drugs. The final protocol can be successfully applied for monitoring concentrations of the selected drugs in both plasma and urine matrices obtained from patients or athletes. Copyright © 2016 Elsevier B.V. All rights reserved.

Phase field modeling of microstructure evolution and concomitant effective conductivity change in solid oxide fuel cell electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lei, Yinkai; Cheng, Tian -Le; Wen, You -Hai

Microstructure evolution plays an important role in the performance degradation of SOFC electrodes. In this work, we propose a much improved phase field model to simulate the microstructure evolution in the electrodes of solid oxide fuel cell. We demonstrate that the tunability of the interfacial energy in this model has been significantly enhanced. Parameters are set to fit for the interfacial energies of a typical Ni-YSZ anode, an LSM-YSZ cathode and an artificial reference electrode, respectively. The contact angles at various triple junctions and the microstructure evolutions in two dimensions are calibrated to verify the model. As a demonstration ofmore » the capabilities of the model, three dimensional microstructure evolutions are simulated applying the model to the three different electrodes. The time evolutions of grain size and triple phase boundary density are analyzed. In addition, a recently proposed bound charge successive approximation algorithm is employed to calculate the effective conductivity of the electrodes during microstructure evolution. Furthermore, the effective conductivity of all electrodes are found to decrease during the microstructure evolution, which is attributed to the increased tortuosity and the loss of percolated volume fraction of the electrode phase.« less

Phase field modeling of microstructure evolution and concomitant effective conductivity change in solid oxide fuel cell electrodes

DOE PAGES

Lei, Yinkai; Cheng, Tian -Le; Wen, You -Hai

2017-02-13

Microstructure evolution plays an important role in the performance degradation of SOFC electrodes. In this work, we propose a much improved phase field model to simulate the microstructure evolution in the electrodes of solid oxide fuel cell. We demonstrate that the tunability of the interfacial energy in this model has been significantly enhanced. Parameters are set to fit for the interfacial energies of a typical Ni-YSZ anode, an LSM-YSZ cathode and an artificial reference electrode, respectively. The contact angles at various triple junctions and the microstructure evolutions in two dimensions are calibrated to verify the model. As a demonstration ofmore » the capabilities of the model, three dimensional microstructure evolutions are simulated applying the model to the three different electrodes. The time evolutions of grain size and triple phase boundary density are analyzed. In addition, a recently proposed bound charge successive approximation algorithm is employed to calculate the effective conductivity of the electrodes during microstructure evolution. Furthermore, the effective conductivity of all electrodes are found to decrease during the microstructure evolution, which is attributed to the increased tortuosity and the loss of percolated volume fraction of the electrode phase.« less

Correlating contact line capillarity and dynamic contact angle hysteresis in surfactant-nanoparticle based complex fluids

NASA Astrophysics Data System (ADS)

Harikrishnan, A. R.; Dhar, Purbarun; Agnihotri, Prabhat K.; Gedupudi, Sateesh; Das, Sarit K.

2018-04-01

Dynamic wettability and contact angle hysteresis can be correlated to shed insight onto any solid-liquid interaction. Complex fluids are capable of altering the expected hysteresis and dynamic wetting behavior due to interfacial interactions. We report the effect of capillary number on the dynamic advancing and receding contact angles of surfactant-based nanocolloidal solutions on hydrophilic, near hydrophobic, and superhydrophobic surfaces by performing forced wetting and de-wetting experiments by employing the embedded needle method. A segregated study is performed to infer the contributing effects of the constituents and effects of particle morphology. The static contact angle hysteresis is found to be a function of particle and surfactant concentrations and greatly depends on the nature of the morphology of the particles. An order of estimate of line energy and a dynamic flow parameter called spreading factor and the transient variations of these parameters are explored which sheds light on the dynamics of contact line movement and response to perturbation of three-phase contact. The Cox-Voinov-Tanner law was found to hold for hydrophilic and a weak dependency on superhydrophobic surfaces with capillary number, and even for the complex fluids, with a varying degree of dependency for different fluids.

On the physically based modeling of surface tension and moving contact lines with dynamic contact angles on the continuum scale

NASA Astrophysics Data System (ADS)

Huber, M.; Keller, F.; Säckel, W.; Hirschler, M.; Kunz, P.; Hassanizadeh, S. M.; Nieken, U.

2016-04-01

The description of wetting phenomena is a challenging problem on every considerable length-scale. The behavior of interfaces and contact lines on the continuum scale is caused by intermolecular interactions like the Van der Waals forces. Therefore, to describe surface tension and the resulting dynamics of interfaces and contact lines on the continuum scale, appropriate formulations must be developed. While the Continuum Surface Force (CSF) model is well-engineered for the description of interfaces, there is still a lack of treatment of contact lines, which are defined by the intersection of an ending fluid interface and a solid boundary surface. In our approach we use a balance equation for the contact line and extend the Navier-Stokes equations in analogy to the extension of a two-phase interface in the CSF model. Since this model depicts a physically motivated approach on the continuum scale, no fitting parameters are introduced and the deterministic description leads to a dynamical evolution of the system. As verification of our theory, we show a Smoothed Particle Hydrodynamics (SPH) model and simulate the evolution of droplet shapes and their corresponding contact angles.

Spatial Distribution of Circadian Clock Phase in Aging Cultures of Neurospora crassa1

PubMed Central

Dharmananda, Subhuti; Feldman, Jerry F.

1979-01-01

Neurospora crassa has been utilized extensively in the study of circadian clocks. Previously, the clock in this organism has been monitored by observing the morphological and biochemical changes occurring at the growing front of cultures grown on solid medium. A method has been developed for assaying the clock in regions of the culture behind the growing front, where no apparent morphological changes occur during the circadian cycle. Using this assay with Petri dish cultures that were 2 to 7 days old, the presence of a functional circadian clock not only at the growing front but in all other regions of the culture as well was demonstrated. Furthermore, the entire culture is not in the same phase, but shows a gradient of phases which is a function of the length of time the clock in a given part of the culture has been free-running. This gradient may be the result of a somewhat longer period of the oscillator behind the growing front compared to that at the growing front. The phase differences within a single culture of interconnected mycelium demonstrate the absence of total internal synchronization between adjacent regions of the hyphae under these conditions. PMID:16660855

Response of microchip solid-state laser to external frequency-shifted feedback and its applications

PubMed Central

Tan, Yidong; Zhang, Shulian; Zhang, Song; Zhang, Yongqing; Liu, Ning

2013-01-01

The response of the microchip solid-state Nd:YAG laser, which is subjected to external frequency-shifted feedback, is experimentally and theoretically analysed. The continuous weak response of the laser to the phase and amplitude of the feedback light is achieved by controlling the feedback power level, and this system can be used to achieve contact-free measurement of displacement, vibration, liquid evaporation and thermal expansion with nanometre accuracy in common room conditions without precise environmental control. Furthermore, a strong response, including chaotic harmonic and parametric oscillation, is observed, and the spectrum of this response, as examined by a frequency-stabilised Nd:YAG laser, indicates laser spectral linewidth broadening. PMID:24105389

Response of microchip solid-state laser to external frequency-shifted feedback and its applications.

PubMed

Tan, Yidong; Zhang, Shulian; Zhang, Song; Zhang, Yongqing; Liu, Ning

2013-10-09

The response of the microchip solid-state Nd:YAG laser, which is subjected to external frequency-shifted feedback, is experimentally and theoretically analysed. The continuous weak response of the laser to the phase and amplitude of the feedback light is achieved by controlling the feedback power level, and this system can be used to achieve contact-free measurement of displacement, vibration, liquid evaporation and thermal expansion with nanometre accuracy in common room conditions without precise environmental control. Furthermore, a strong response, including chaotic harmonic and parametric oscillation, is observed, and the spectrum of this response, as examined by a frequency-stabilised Nd:YAG laser, indicates laser spectral linewidth broadening.

Carbon nanotube enhanced label-free detection of microRNAs based on hairpin probe triggered solid-phase rolling-circle amplification

NASA Astrophysics Data System (ADS)

Tian, Qianqian; Wang, Ying; Deng, Ruijie; Lin, Lei; Liu, Yang; Li, Jinghong

2014-12-01

The detection of microRNAs (miRNAs) is imperative for gaining a better understanding of the functions of these biomarkers and has great potential for the early diagnosis of human disease. High sensitivity and selectivity for miRNA detection brings new challenges. Herein, an ultrasensitive protocol for electrochemical detection of miRNA is designed through carbon nanotube (CNT) enhanced label-free detection based on hairpin probe triggered solid-phase rolling-circle amplification (RCA). Traditionally, RCA, widely applied for signal enhancement in the construction of a variety of biosensors, has an intrinsic limitation of ultrasensitive detection, as it is difficult to separate the enzymes, templates, and padlock DNAs from the RCA products in the homogeneous solution. We purposely designed a solid-phase RCA strategy, using CNTs as the solid substrate, integrated with a hairpin structured probe to recognize target miRNA. In the presence of miRNA the stem-loop structure will be unfolded, triggering the CNT based RCA process. Due to the efficient blocking effect originating from the polymeric RCA products, the label-free assay of miRNA exhibits an ultrasensitive detection limit of 1.2 fM. Furthermore, the protocol possesses excellent specificity for resolving lung cancer-related let-7 family members which have only one-nucleotide variations. The high sensitivity and selectivity give the method great potential for applications in online diagnostics and in situ detection in long-term development.The detection of microRNAs (miRNAs) is imperative for gaining a better understanding of the functions of these biomarkers and has great potential for the early diagnosis of human disease. High sensitivity and selectivity for miRNA detection brings new challenges. Herein, an ultrasensitive protocol for electrochemical detection of miRNA is designed through carbon nanotube (CNT) enhanced label-free detection based on hairpin probe triggered solid-phase rolling-circle amplification (RCA). Traditionally, RCA, widely applied for signal enhancement in the construction of a variety of biosensors, has an intrinsic limitation of ultrasensitive detection, as it is difficult to separate the enzymes, templates, and padlock DNAs from the RCA products in the homogeneous solution. We purposely designed a solid-phase RCA strategy, using CNTs as the solid substrate, integrated with a hairpin structured probe to recognize target miRNA. In the presence of miRNA the stem-loop structure will be unfolded, triggering the CNT based RCA process. Due to the efficient blocking effect originating from the polymeric RCA products, the label-free assay of miRNA exhibits an ultrasensitive detection limit of 1.2 fM. Furthermore, the protocol possesses excellent specificity for resolving lung cancer-related let-7 family members which have only one-nucleotide variations. The high sensitivity and selectivity give the method great potential for applications in online diagnostics and in situ detection in long-term development. Electronic supplementary information (ESI) available: Preparation of the chemically modified multi-walled carbon nanotubes (CNTs), characterization of the CNTs and modified CNTs, preparation of the circular probe, gel electrophoresis of the RCA products, and DNA probes as noted in the text. See DOI: 10.1039/c4nr05243a

New Signal Readout Principle for Solid-Contact Ion-Selective Electrodes.

PubMed

Vanamo, Ulriika; Hupa, Elisa; Yrjänä, Ville; Bobacka, Johan

2016-04-19

A novel approach to signal transduction concerning solid-contact ion-selective electrodes (SC-ISE) with a conducting polymer (CP) as the solid contact is investigated. The method presented here is based on constant potential coulometry, where the potential of the SC-ISE vs the reference electrode is kept constant using a potentiostat. The change in the potential at the interface between the ion-selective membrane (ISM) and the sample solution, due to the change in the activity of the primary ion, is compensated with a corresponding but opposite change in the potential of the CP solid contact. This enforced change in the potential of the solid contact results in a transient reducing/oxidizing current flow through the SC-ISE. By measuring and integrating the current needed to transfer the CP to a new state of equilibrium, the total cumulated charge that is linearly proportional to the change of the logarithm of the primary ion activity is obtained. In this work, different thicknesses of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(styrenesulfonate) (PSS) were used as solid contact. Also, coated wire electrodes (CWEs) were included in the study to show the general validity of the new approach. The ISM employed was selective for K(+) ions, and the selectivity of the membrane under implementation of the presented transduction mechanism was confirmed by measurements performed with a constant background concentration of Na(+) ions. A unique feature of this signal readout principle is that it allows amplification of the analytical signal by increasing the capacitance (film thickness) of the solid contact of the SC-ISE.

The use of ethanol:diethylphthalate as a vehicle for the local lymph node assay.

PubMed

Betts, Catherine J; Beresford, L; Dearman, R J; Lalko, J; Api, A P; Kimber, I

2007-02-01

The murine local lymph node assay (LLNA) is used for the prospective identification of contact allergens. This method is not only accepted as a stand-alone test for the identification of contact allergenic hazard but also used increasingly for the measurement of the relative potency of skin-sensitizing chemicals as an integral component of the risk assessment process. During the development and validation phases of the method, a list of standard vehicles for use in the LLNA was identified, among them being the vehicle most commonly used acetone/olive oil (4:1, AOO). We have now explored the performance in the LLNA of a non-standard vehicle, ethanol:diethyl phthalate (1:3, EtOH:DEP), that is used frequently to evaluate dermal effects of fragrance materials in both human and experimental studies. Current investigations have demonstrated that EtOH:DEP induces similar levels of background proliferative responses in lymph nodes comparable with the standard vehicle AOO. Moreover, expected levels of activity are observed when EtOH:DEP is used to deliver a known contact allergen in the LLNA. The conclusion drawn is that EtOH:DEP provides a suitable vehicle for use in the LLNA and that the approach described provides a basis for future evaluation of novel vehicles.

Improving the dissolution rate of poorly water soluble drug by solid dispersion and solid solution: pros and cons.

PubMed

Chokshi, Rina J; Zia, Hossein; Sandhu, Harpreet K; Shah, Navnit H; Malick, Waseem A

2007-01-01

The solid dispersions with poloxamer 188 (P188) and solid solutions with polyvinylpyrrolidone K30 (PVPK30) were evaluated and compared in an effort to improve aqueous solubility and bioavailability of a model hydrophobic drug. All preparations were characterized by differential scanning calorimetry, powder X-ray diffraction, intrinsic dissolution rates, and contact angle measurements. Accelerated stability studies also were conducted to determine the effects of aging on the stability of various formulations. The selected solid dispersion and solid solution formulations were further evaluated in beagle dogs for in vivo testing. Solid dispersions were characterized to show that the drug retains its crystallinity and forms a two-phase system. Solid solutions were characterized to be an amorphous monophasic system with transition of crystalline drug to amorphous state. The evaluation of the intrinsic dissolution rates of various preparations indicated that the solid solutions have higher initial dissolution rates compared with solid dispersions. However, after storage at accelerated conditions, the dissolution rates of solid solutions were lower due to partial reversion to crystalline form. The drug in solid dispersion showed better bioavailability in comparison to solid solution. Therefore, considering physical stability and in vivo study results, the solid dispersion was the most suitable choice to improve dissolution rates and hence the bioavailability of the poorly water soluble drug.

From in silica to in silico: retention thermodynamics at solid-liquid interfaces.

PubMed

El Hage, Krystel; Bemish, Raymond J; Meuwly, Markus

2018-06-28

The dynamics of solvated molecules at the solid/liquid interface is essential for a molecular-level understanding for the solution thermodynamics in reversed phase liquid chromatography (RPLC). The heterogeneous nature of the systems and the competing intermolecular interactions makes solute retention in RPLC a surprisingly challenging problem which benefits greatly from modelling at atomistic resolution. However, the quality of the underlying computational model needs to be sufficiently accurate to provide a realistic description of the energetics and dynamics of systems, especially for solution-phase simulations. Here, the retention thermodynamics and the retention mechanism of a range of benzene-derivatives in C18 stationary-phase chains in contact with water/methanol mixtures is studied using point charge (PC) and multipole (MTP) electrostatic models. The results demonstrate that free energy simulations with a faithful MTP representation of the computational model provide quantitative and molecular level insight into the thermodynamics of adsorption/desorption in chromatographic systems while a conventional PC representation fails in doing so. This provides a rational basis to develop more quantitative and validated models for the optimization of separation systems.

Effects of viscoelasticity on drop impact and spreading on a solid surface

NASA Astrophysics Data System (ADS)

Izbassarov, Daulet; Muradoglu, Metin

2016-06-01

The effects of viscoelasticity on drop impact and spreading on a flat solid surface are studied computationally using a finite-difference-front-tracking method. The finitely extensible nonlinear elastic-Chilcott-Rallison model is used to account for the fluid viscoelasticity. It is found that viscoelasticity favors advancement of contact line during the spreading phase, leading to a slight increase in the maximum spreading, in agreement with experimental observations [Huh, Jung, Seo, and Lee, Microfluid. Nanofluid. 18, 1221 (2015), 10.1007/s10404-014-1518-4]. However, in contrast with the well-known antirebound effects of polymeric additives, the viscoelasticity is found to enhance the tendency of the drop rebound in the receding phase. These results suggest that the antirebound effects are mainly due to the polymer-induced modification of wetting properties of the substrate rather than the change in the material properties of the drop fluid. A model is proposed to test this hypothesis. It is found that the model results in good qualitative agreement with the experimental observations and the antirebound behavior can be captured by the modification of surface wetting properties in the receding phase.

Preparation and characterization of solid dispersion freeze-dried efavirenz - polyvinylpyrrolidone K-30.

PubMed

Fitriani, Lili; Haqi, Alianshar; Zaini, Erizal

2016-01-01

The aim of this research is to prepare and characterize solid dispersion of efavirenz - polyvinylpyrrolidone (PVP) K-30 by freeze drying to increase its solubility. Solid dispersion of efavirenz - PVP K-30 was prepared by solvent evaporation method with ratio 2:1, 1:1, and 1:2 and dried using a freeze dryer. Characterizations were done by scanning electron microscopy (SEM), powder X-ray diffraction analysis, differential thermal analysis (DTA), and Fourier transform infrared (FT-IR) spectroscopy. Solubility test was carried out in CO2-free distilled water, and efavirenz assay was conducted using high-performance liquid chromatography with acetonitrile:acetic acid (80:20) as the mobile phases. Powder X-ray diffractogram showed a decrease in the peak intensity, which indicated the crystalline altered to amorphous phase. DTA thermal analysis showed a decrease in the melting point of the solid dispersion compared to intact efavirenz. SEM results indicated the changes in the morphology of the crystal into an amorphous form compared to pure components. FT-IR spectroscopy analysis showed a shift wavenumber of the spectrum efavirenz and PVP K-30. The solubility of solid dispersion at ratio 2:1, 1:1, and 1:2 was 6.777 μg/mL, 6.936 μg/mL, and 14,672 μg/mL, respectively, whereas the solubility of intact efavirenz was 0.250 μg/mL. In conclusion, the solubility of solid dispersion increased significantly (P < 0.05).

Assessing the failure of continuum formula for solid-solid drag force using discrete element method in large size ratios

NASA Astrophysics Data System (ADS)

Jalali, Payman; Hyppänen, Timo

2017-06-01

In loose or moderately-dense particle mixtures, the contact forces between particles due to successive collisions create average volumetric solid-solid drag force between different granular phases (of different particle sizes). The derivation of the mathematical formula for this drag force is based on the homogeneity of mixture within the calculational control volume. This assumption especially fails when the size ratio of particles grows to a large value of 10 or greater. The size-driven inhomogeneity is responsible to the deviation of intergranular force from the continuum formula. In this paper, we have implemented discrete element method (DEM) simulations to obtain the volumetric mean force exchanged between the granular phases with the size ratios greater than 10. First, the force is calculated directly from DEM averaged over a proper time window. Second, the continuum formula is applied to calculate the drag forces using the DEM quantities. We have shown the two volumetric forces are in good agreement as long as the homogeneity condition is maintained. However, the relative motion of larger particles in a cloud of finer particles imposes the inhomogeneous distribution of finer particles around the larger ones. We have presented correction factors to the volumetric force from continuum formula.

Ca(2+)-triggered coelenterazine-binding protein from Renilla as an enzyme-dependent label for binding assay.

PubMed

Krasitskaya, V V; Korneeva, S I; Kudryavtsev, A N; Markova, S V; Stepanyuk, G A; Frank, L A

2011-11-01

The recombinant Ca(2+)-triggered coelenterazine-binding protein (CBP) from Renilla muelleri was investigated as a biospecifically labeled molecule for in vitro assay applications. The protein was shown to be stable in solutions in the frozen state, as well as stable under heating and to chemical modifications. Conjugates with biotin, oligonucleotide, and proteins were obtained and applied as biospecific molecules in a solid-phase microassay. CBP detection was performed with intact (no modifications were made) Renilla luciferase in the presence of calcium, and the detection limit was found to be 75 amol. Model experiments indicate that this approach shows much promise, especially with regard to the development of multianalytical systems.

Characterization of matrix effects in developing rugged high-throughput LC-MS/MS methods for bioanalysis.

PubMed

Li, Fumin; Wang, Jun; Jenkins, Rand

2016-05-01

There is an ever-increasing demand for high-throughput LC-MS/MS bioanalytical assays to support drug discovery and development. Matrix effects of sofosbuvir (protonated) and paclitaxel (sodiated) were thoroughly evaluated using high-throughput chromatography (defined as having a run time ≤1 min) under 14 elution conditions with extracts from protein precipitation, liquid-liquid extraction and solid-phase extraction. A slight separation, in terms of retention time, between underlying matrix components and sofosbuvir/paclitaxel can greatly alleviate matrix effects. High-throughput chromatography, with proper optimization, can provide rapid and effective chromatographic separation under 1 min to alleviate matrix effects and enhance assay ruggedness for regulated bioanalysis.

75 FR 37443 - National Toxicology Program (NTP); NTP Interagency Center for the Evaluation of Alternative...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-29

... Nonradioactive Versions of the Murine Local Lymph Node Assay for Assessing Allergic Contact Dermatitis Hazard... nonradioactive versions of the Local Lymph Node Assay (LLNA) for assessing allergic contact dermatitis (ACD... Nonradioactive Alternative Test Method to Assess the Allergic Contact Dermatitis Potential of Chemicals and...

Electrification of particulate entrained fluid flows-Mechanisms, applications, and numerical methodology

NASA Astrophysics Data System (ADS)

Wei, Wei; Gu, Zhaolin

2015-10-01

Particulates in natural and industrial flows have two basic forms: liquid (droplet) and solid (particle). Droplets would be charged in the presence of the applied electric field (e.g. electrospray). Similar to the droplet charging, particles can also be charged under the external electric field (e.g. electrostatic precipitator), while in the absence of external electric field, tribo-electrostatic charging is almost unavoidable in gas-solid two-phase flows due to the consecutive particle contacts (e.g. electrostatic in fluidized bed or wind-blown sand). The particle charging may be beneficial, or detrimental. Although electrostatics in particulate entrained fluid flow systems have been so widely used and concerned, the mechanisms of particulate charging are still lack of a thorough understanding. The motivation of this review is to explore a clear understanding of particulate charging and movement of charged particulate in two-phase flows, by summarizing the electrification mechanisms, physical models of particulate charging, and methods of charging/charged particulate entrained fluid flow simulations. Two effective methods can make droplets charged in industrial applications: corona charging and induction charging. The droplet charge to mass ratio by corona charging is more than induction discharge. The particle charging through collisions could be attributed to electron transfer, ion transfer, material transfer, and/or aqueous ion shift on particle surfaces. The charges on charged particulate surface can be measured, nevertheless, the charging process in nature or industry is difficult to monitor. The simulation method might build a bridge of investigating from the charging process to finally charged state on particulate surface in particulate entrained fluid flows. The methodology combining the interface tracking under the action of the applied electric with the fluid flow governing equations is applicable to the study of electrohydrodynamics problems. The charge distribution and mechanical behaviors of liquid surface can be predicted by using this method. The methodology combining particle charging model with Computational Fluid Dynamics (CFD) and Discrete element method (DEM) is applicable to study the particle charging/charged processes in gas-solid two phase flows, the influence factors of particle charging, such as gas-particle interaction, contact force, contact area, and various velocities, are described systematically. This review would explore a clear understanding of the particulate charging and provide theoretical references to control and utilize the charging/charged particulate entrained fluid system.

[Solid phase radioimmunoassay for plasma testosterone using plastic microtiter tray (author's transl)].

PubMed

Hosogi, H

1975-03-20

In order to simply radioimmunoassay for plasma testosterone and to measure many samples at the same time, a method of solid phase radioimmunoassay utilizing a plastic disposable microtiter tray (DMT) by which chromatography can be omitted was investigated. The antiserum was obtained by immunizing rabbits with testosterone-3 BSA which had been synthesized according to the Erlarnger's method. Plasma samples (male: 0.05ml, female: 0.2 ml) were extracted with 1.0 ml of ether. After freezing the plasma layer in an acetone-dryice bath, the ether phase was transfered to a glass tube and evaporated to dryness. These samples and the dried standard testosterone were dissolved with borate buffer containing 3H-testosterone and transfered to plastic DMT which had been precoated with the diluted antiserum, and incubated for 24 hrs. After removal of the incubated solution, the cups of DMT were cut off and were dissolved with toluene scintillator in counting vials. The radioactivity was counted with a liquid scintillation counter. Other steroids except for 5alpha-dihydrotestosterone (5alpha-DHT) had a low degree of cross reactivity with the antiserum. Five alpha-DHT which could be measured together with testosterone in this assay was not a problem clinically because of its strong androgenic activity. The best standard curve was obtained when the antiserum was diluted to 1:1000. The sensitivity of this assay was 10 pg/tube. The maximal adsorption of antibody to plastic DMT was observed when the pH of antiserum was within the range of 6.5-9.5 and the precoating time was 24 hr at room termperature. The best pH of incubation buffer was 8.0, and the antigen-antibody reaction became a plateau when the incubation exceeded 6 hrs. Water blank in this assay was 4.6 +/- 2.1 pg/tube. The recovery of testosterone (50, 100, 200 pg) added to 0.1 ml female plasma was 99 +/- 6.8%. Coefficients of variation within assay and between assay were below 11.2% and 20.0%, respectively. Correlation between this method and the dextran-coated charcoal method was fairly good (r=0.938). Plasma testosterone levels in 10 normal males and 12 normal females were 616 +/- 202 (mean +/- SD) ng/dl and 66 +/- 29 (mean +/- SD) ng/dl, respectively. The levels were low in patients with hypopituitarism, hypogonadism and acromegaly. They were normal in patients with Cushing's syndrome due to adrenal hyperplasia and adenoma, but they were high in a patient with adrenal carcinoma. In a patient with testicular feminization, the level was 632 ng/dl. This increased after the administration of HCG, and decreased to 127.5 ng/dl after castration. This solid phase radioimmunoassay (using plastic DMT) is economically feasible as well as simple because it is possible to separate the bound hormone from the free hormone of all samples at the same time and there is little restriction in time and temperature. According to the above results, this method is suitable for routine clinical use.

All-Solid-State Sodium-Selective Electrode with a Solid Contact of Chitosan/Prussian Blue Nanocomposite

PubMed Central

Ghosh, Tanushree; Rieger, Jana

2017-01-01

Conventional ion-selective electrodes with a liquid junction have the disadvantage of potential drift. All-solid-state ion-selective electrodes with solid contact in between the metal electrode and the ion-selective membrane offer high capacitance or conductance to enhance potential stability. Solution-casted chitosan/Prussian blue nanocomposite (ChPBN) was employed as the solid contact layer for an all-solid-state sodium ion-selective electrode in a potentiometric sodium ion sensor. Morphological and chemical analyses confirmed that the ChPBN is a macroporous network of chitosan that contains abundant Prussian blue nanoparticles. Situated between a screen-printed carbon electrode and a sodium-ionophore-filled polyvinylchloride ion-selective membrane, the ChPBN layer exhibited high redox capacitance and fast charge transfer capability, which significantly enhanced the performance of the sodium ion-selective electrode. A good Nernstian response with a slope of 52.4 mV/decade in the linear range from 10−4–1 M of NaCl was observed. The stability of the electrical potential of the new solid contact was tested by chronopotentiometry, and the capacitance of the electrode was 154 ± 4 µF. The response stability in terms of potential drift was excellent (1.3 µV/h) for 20 h of continuous measurement. The ChPBN proved to be an efficient solid contact to enhance the potential stability of the all-solid-state ion-selective electrode. PMID:29099804

Toward a solid-phase nucleic acid hybridization assay within microfluidic channels using immobilized quantum dots as donors in fluorescence resonance energy transfer.

PubMed

Chen, Lu; Algar, W Russ; Tavares, Anthony J; Krull, Ulrich J

2011-01-01

The optical properties and surface area of quantum dots (QDs) have made them an attractive platform for the development of nucleic acid biosensors based on fluorescence resonance energy transfer (FRET). Solid-phase assays based on FRET using mixtures of immobilized QD-oligonucleotide conjugates (QD biosensors) have been developed. The typical challenges associated with solid-phase detection strategies include non-specific adsorption, slow kinetics of hybridization, and sample manipulation. The new work herein has considered the immobilization of QD biosensors onto the surfaces of microfluidic channels in order to address these challenges. Microfluidic flow can be used to dynamically control stringency by adjustment of the potential in an electrokinetic-based microfluidics environment. The shearing force, Joule heating, and the competition between electroosmotic and electrophoretic mobilities allow the optimization of hybridization conditions, convective delivery of target to the channel surface to speed hybridization, amelioration of adsorption, and regeneration of the sensing surface. Microfluidic flow can also be used to deliver (for immobilization) and remove QD biosensors. QDs that were conjugated with two different oligonucleotide sequences were used to demonstrate feasibility. One oligonucleotide sequence on the QD was available as a linker for immobilization via hybridization with complementary oligonucleotides located on a glass surface within a microfluidic channel. A second oligonucleotide sequence on the QD served as a probe to transduce hybridization with target nucleic acid in a sample solution. A Cy3 label on the target was excited by FRET using green-emitting CdSe/ZnS QD donors and provided an analytical signal to explore this detection strategy. The immobilized QDs could be removed under denaturing conditions by disrupting the duplex that was used as the surface linker and thus allowed a new layer of QD biosensors to be re-coated within the channel for re-use of the microfluidic chip.

Preparation and characterization of Mg-Zr mixed oxide aerogels and their application as aldol condensation catalysts.

PubMed

Sádaba, Irantzu; Ojeda, Manuel; Mariscal, Rafael; Richards, Ryan; López Granados, Manuel

2012-10-08

A series of Mg-Zr mixed oxides with different nominal Mg/(Mg+Zr) atomic ratios, namely 0, 0.1, 0.2, 0.4, 0.85, and 1, is prepared by alcogel methodology and fundamental insights into the phases obtained and resulting active sites are studied. Characterization is performed by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, N(2) adsorption-desorption isotherms, and thermal and chemical analysis. Cubic Mg(x)Zr(1-x)O(2-x) solid solution, which results from the dissolution of Mg(2+) cations within the cubic ZrO(2) structure, is the main phase detected for the solids with theoretical Mg/(Mg+Zr) atomic ratio ≤0.4. In contrast, the cubic periclase (c-MgO) phase derived from hydroxynitrates or hydroxy precursors predominates in the solid with Mg/(Mg+Zr)=0.85. c-MgO is also incipiently detected in samples with Mg/(Mg+Zr)=0.2 and 0.4, but in these solids the c-MgO phase mostly arises from the segregation of Mg atoms out of the alcogel-derived c-Mg(x)Zr(1-x)O(2-x) phase during the calcination process, and therefore the species c-MgO and c-Mg(x)Zr(1-x)O(2-x) are in close contact. Regarding the intrinsic activity in furfural-acetone aldol condensation in the aqueous phase, these Mg-O-Zr sites located at the interface between c-Mg(x)Zr(1-x)O(2-x) and segregated c-MgO display a much larger intrinsic activity than the other noninterface sites that are present in these catalysts: Mg-O-Mg sites on c-MgO and Mg-O-Zr sites on c-Mg(x)Zr(1-x)O(2-x). The very active Mg-O-Zr sites rapidly deactivate in the furfural-acetone condensation due to the leaching of active phases, deposition of heavy hydrocarbonaceous compounds, and hydration of the c-MgO phase. Nonetheless, these Mg-Zr materials with very high specific surface areas would be suitable solid catalysts for other relevant reactions catalyzed by strong basic sites in nonaqueous environments. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Immunoassay of paralytic shellfish toxins by moving magnetic particles in a stationary liquid-phase lab-on-a-chip.

PubMed

Kim, Myoung-Ho; Choi, Suk-Jung

2015-04-15

In this study, we devised a stationary liquid-phase lab-on-a-chip (SLP LOC), which was operated by moving solid-phase magnetic particles in the stationary liquid phase. The SLP LOC consisted of a sample chamber to which a sample and reactants were added, a detection chamber containing enzyme substrate solution, and a narrow channel connecting the two chambers and filled with buffer. As a model system, competitive immunoassays of saxitoxin (STX), a paralytic shellfish toxin, were conducted in the SLP LOC using protein G-coupled magnetic particles (G-MPs) as the solid phase. Anti-STX antibodies, STX-horseradish peroxidase conjugate, G-MPs, and a STX sample were added to the sample chamber and reacted by shaking. While liquids were in the stationary state, G-MPs were transported from the sample chamber to the detection chamber by moving a magnet below the LOC. After incubation to allow the enzymatic reaction to occur, the absorbance of the detection chamber solution was found to be reciprocally related to the STX concentration of the sample. Thus, the SLP LOC may represent a novel, simple format for point-of-care testing applications of enzyme-linked immunosorbent assays by eliminating complicated liquid handling steps. Copyright © 2014 Elsevier B.V. All rights reserved.

Spontaneous Spreading of a Droplet: The Role of Solid Continuity and Advancing Contact Angle.

PubMed

Jiang, Youhua; Sun, Yujin; Drelich, Jaroslaw W; Choi, Chang-Hwan

2018-05-01

Spontaneous spreading of a droplet on a solid surface is poorly understood from a macroscopic level down to a molecular level. Here, we investigate the effect of surface topography and wettability on spontaneous spreading of a water droplet. Spreading force is measured for a suspended droplet that minimizes interference of kinetic energy in the spontaneous spreading during its contact with solid surfaces of discontinuous (pillar) and continuous (pore) patterns with various shapes and dimensions. Results show that a droplet cannot spread spontaneously on pillared surfaces regardless of their shapes or dimensions because of the solid discontinuity. On the contrary, a droplet on pored surfaces can undergo spontaneous spreading whose force increases with a decrease in the advancing contact angle. Theoretical models based on both the system free energy and capillary force along the contact line validate the direct and universal dependency of the spontaneous spreading force on the advancing contact angle.

Automatic measurement of contact angle in pore-space images

NASA Astrophysics Data System (ADS)

AlRatrout, Ahmed; Raeini, Ali Q.; Bijeljic, Branko; Blunt, Martin J.

2017-11-01

A new approach is presented to measure the in-situ contact angle (θ) between immiscible fluids, applied to segmented pore-scale X-ray images. We first identify and mesh the fluid/fluid and fluid/solid interfaces. A Gaussian smoothing is applied to this mesh to eliminate artifacts associated with the voxelized nature of the image, while preserving large-scale features of the rock surface. Then, for the fluid/fluid interface we apply an additional smoothing and adjustment of the mesh to impose a constant curvature. We then track the three-phase contact line, and the two vectors that have a direction perpendicular to both surfaces: the contact angle is found from the dot product of these vectors where they meet at the contact line. This calculation can be applied at every point on the mesh at the contact line. We automatically generate contact angle values representing each invaded pore-element in the image with high accuracy. To validate the approach, we first study synthetic three-dimensional images of a spherical droplet of oil residing on a tilted flat solid surface surrounded by brine and show that our results are accurate to within 3° if the sphere diameter is 2 or more voxels. We then apply this method to oil/brine systems imaged at ambient temperature and reservoir pressure (10MPa) using X-ray microtomography (Singh et al., 2016). We analyse an image volume of diameter approximately 4.6 mm and 10.7 mm long, obtaining hundreds of thousands of values from a dataset with around 700 million voxels. We show that in a system of altered wettability, contact angles both less than and greater than 90° can be observed. This work provides a rapid method to provide an accurate characterization of pore-scale wettability, which is important for the design and assessment of hydrocarbon recovery and carbon dioxide storage.

A collision model for grain-resolving simulations of flows over dense, mobile, polydisperse granular sediment beds

DOE PAGES

Biegert, Edward; Vowinckel, Bernhard; Meiburg, Eckart

2017-03-21

We present a collision model for phase-resolved Direct Numerical Simulations of sediment transport that couple the fluid and particles by the Immersed Boundary Method. Typically, a contact model for these types of simulations comprises a lubrication force for particles in close proximity to another solid object, a normal contact force to prevent particles from overlapping, and a tangential contact force to account for friction. Our model extends the work of previous authors to improve upon the time integration scheme to obtain consistent results for particle-wall collisions. Furthermore, we account for polydisperse spherical particles and introduce new criteria to account formore » enduring contact, which occurs in many sediment transport situations. This is done without using arbitrary values for physically-defined parameters and by maintaining the full momentum balance of a particle in enduring contact. Lastly, we validate our model against several test cases for binary particle-wall collisions as well as the collective motion of a sediment bed sheared by a viscous flow, yielding satisfactory agreement with experimental data by various authors.« less

A collision model for grain-resolving simulations of flows over dense, mobile, polydisperse granular sediment beds

NASA Astrophysics Data System (ADS)

Biegert, Edward; Vowinckel, Bernhard; Meiburg, Eckart

2017-07-01

We present a collision model for phase-resolved Direct Numerical Simulations of sediment transport that couple the fluid and particles by the Immersed Boundary Method. Typically, a contact model for these types of simulations comprises a lubrication force for particles in close proximity to another solid object, a normal contact force to prevent particles from overlapping, and a tangential contact force to account for friction. Our model extends the work of previous authors to improve upon the time integration scheme to obtain consistent results for particle-wall collisions. Furthermore, we account for polydisperse spherical particles and introduce new criteria to account for enduring contact, which occurs in many sediment transport situations. This is done without using arbitrary values for physically-defined parameters and by maintaining the full momentum balance of a particle in enduring contact. We validate our model against several test cases for binary particle-wall collisions as well as the collective motion of a sediment bed sheared by a viscous flow, yielding satisfactory agreement with experimental data by various authors.

Geometrical control of dissipation during the spreading of liquids on soft solids

NASA Astrophysics Data System (ADS)

Zhao, Menghua; Dervaux, Julien; Narita, Tetsuharu; Lequeux, François; Limat, Laurent; Roché, Matthieu

2018-02-01

Gel layers bound to a rigid substrate are used in cell culture to control differentiation and migration and to lower the friction and tailor the wetting of solids. Their thickness, often considered a negligible parameter, affects cell mechanosensing or the shape of sessile droplets. Here, we show that the adjustment of coating thickness provides control over energy dissipation during the spreading of flowing matter on a gel layer. We combine experiments and theory to provide an analytical description of both the statics and the dynamics of the contact line between the gel, the liquid, and the surrounding atmosphere. We extract from this analysis a hitherto-unknown scaling law that predicts the dynamic contact angle between the three phases as a function of the properties of the coating and the velocity of the contact line. Finally, we show that droplets moving on vertical substrates coated with gel layers having linear thickness gradients drift toward regions of higher energy dissipation. Thus, thickness control opens the opportunity to design a priori the path followed by large droplets moving on gel-coated substrates. Our study shows that thickness is another parameter, besides surface energy and substrate mechanics, to tune the dynamics of liquid spreading and wetting on a compliant coating, with potential applications in dew collection and free-surface flow control.

Linking Findings in Microfluidics to Membrane Emulsification Process Design: The Importance of Wettability and Component Interactions with Interfaces

PubMed Central

Schroën, Karin; Ferrando, Montse; de Lamo-Castellví, Silvia; Sahin, Sami; Güell, Carme

2016-01-01

In microfluidics and other microstructured devices, wettability changes, as a result of component interactions with the solid wall, can have dramatic effects. In emulsion separation and emulsification applications, the desired behavior can even be completely lost. Wettability changes also occur in one phase systems, but the effect is much more far-reaching when using two-phase systems. For microfluidic emulsification devices, this can be elegantly demonstrated and quantified for EDGE (Edge-base Droplet GEneration) devices that have a specific behavior that allows us to distinguish between surfactant and liquid interactions with the solid surface. Based on these findings, design rules can be defined for emulsification with any micro-structured emulsification device, such as direct and premix membrane emulsification. In general, it can be concluded that mostly surface interactions increase the contact angle toward 90°, either through the surfactant, or the oil that is used. This leads to poor process stability, and very limited pressure ranges at which small droplets can be made in microfluidic systems, and cross-flow membrane emulsification. In a limited number of cases, surface interactions can also lead to lower contact angles, thereby increasing the operational stability. This paper concludes with a guideline that can be used to come to the appropriate combination of membrane construction material (or any micro-structured device), surfactants and liquids, in combination with process conditions. PMID:27187484

Apparent-contact-angle model at partial wetting and evaporation: impact of surface forces.

PubMed

Janeček, V; Nikolayev, V S

2013-01-01

This theoretical and numerical study deals with evaporation of a fluid wedge in contact with its pure vapor. The model describes a regime where the continuous wetting film is absent and the actual line of the triple gas-liquid-solid contact appears. A constant temperature higher than the saturation temperature is imposed at the solid substrate. The fluid flow is solved in the lubrication approximation. The introduction of the surface forces in the case of the partial wetting is discussed. The apparent contact angle (the gas-liquid interface slope far from the contact line) is studied numerically as a function of the substrate superheating, contact line velocity, and parameters related to the solid-fluid interaction (Young and microscopic contact angles, Hamaker constant, etc.). The dependence of the apparent contact angle on the substrate temperature is in agreement with existing approaches. For water, the apparent contact angle may be 20° larger than the Young contact angle for 1 K superheating. The effect of the surface forces on the apparent contact angle is found to be weak.

Apparent-contact-angle model at partial wetting and evaporation: Impact of surface forces

NASA Astrophysics Data System (ADS)

Janeček, V.; Nikolayev, V. S.

2013-01-01

This theoretical and numerical study deals with evaporation of a fluid wedge in contact with its pure vapor. The model describes a regime where the continuous wetting film is absent and the actual line of the triple gas-liquid-solid contact appears. A constant temperature higher than the saturation temperature is imposed at the solid substrate. The fluid flow is solved in the lubrication approximation. The introduction of the surface forces in the case of the partial wetting is discussed. The apparent contact angle (the gas-liquid interface slope far from the contact line) is studied numerically as a function of the substrate superheating, contact line velocity, and parameters related to the solid-fluid interaction (Young and microscopic contact angles, Hamaker constant, etc.). The dependence of the apparent contact angle on the substrate temperature is in agreement with existing approaches. For water, the apparent contact angle may be 20∘ larger than the Young contact angle for 1 K superheating. The effect of the surface forces on the apparent contact angle is found to be weak.

Effect of air confinement on thermal contact resistance in nanoscale heat transfer

NASA Astrophysics Data System (ADS)

Pratap, Dheeraj; Islam, Rakibul; Al-Alam, Patricia; Randrianalisoa, Jaona; Trannoy, Nathalie

2018-03-01

Here, we report a detailed analysis of thermal contact resistance (R c) of nano-size contact formed between a Wollaston wire thermal probe and the used samples (fused silica and titanium) as a function of air pressure (from 1 Pa to 105 Pa). Moreover, we suggest an analytical model using experimental data to extract R c. We found that for both samples, the thermal contact resistance decreases with increasing air pressure. We also showed that R c strongly depends on the thermal conductivity of materials keeping other parameters the same, such as roughness of the probe and samples, as well as the contact force. We provide a physical explanation of the R c trend with pressure and thermal conductivity of the materials: R c is ascribed to the heat transfer through solid-solid (probe-sample) contact and confined air at nanoscale cavities, due to the rough nature of the materials in contact. The contribution of confined air on heat transfer through the probe sample contact is significant at atmospheric pressure but decreases as the pressure decreases. In vacuum, only the solid-solid contact contributes to R c. In addition, theoretical calculations using the well-known acoustic and diffuse mismatch models showed a high thermal conductivity material that exhibits high heat transmission and consequently low R c, supporting our findings.

How Does a Liquid Wet a Solid? Hydrodynamics of Dynamic Contact Angles

NASA Technical Reports Server (NTRS)

Rame, Enrique

2001-01-01

A contact line is defined at the intersection of a solid surface with the interface between two immiscible fluids. When one fluid displaces another immiscible fluid along a solid surface, the process is called dynamic wetting and a "moving" contact line (one whose position relative to the solid changes in time) often appears. The physics of dynamic wetting controls such natural and industrial processes as spraying of paints and insecticides, dishwashing, film formation and rupture in the eye and in the alveoli, application of coatings, printing, drying and imbibition of fibrous materials, oil recovery from porous rocks, and microfluidics.

On-line solid phase extraction coupled to capillary LC-ESI-MS for determination of fluoxetine in human blood plasma.

PubMed

Saber, Amr L

2009-04-15

An instrumental setup including on-line solid phased extraction coupled to capillary liquid chromatography-electrospray ionization-mass spectrometry (SPE-capLC-ESI-MS) has been constructed to improve the sensitivity for quantification of fluoxetine hydrochloride in human plasma. Prior to injection, 0.5 mL of plasma spiked with metronidazole (internal standard) was mixed with ammonium formate buffer for effective chloroform liquid-liquid extraction. The method was validated in the range 5-60 ng mL(-1) fluoxetine, yielding a correlation coefficient of 0.999 (r(2)). The within-assay and between-assay precisions were between (8.5 and 11%) and (6.6 and 7.5%), respectively. The method was used to determine the amount of fluoxetine in a healthy male 14 h after an intake of one capsule of the antidepressant and anorectic Flutin, which contains 20mg fluoxetine per each capsule. Fluoxetine was detected, and the concentration was calculated to 9.0 ng mL(-1) plasma. In the preliminary experiments, conventional LC-UV instrumentation was employed. However, it was found that employing a capillary column with an inner diameter of (0.3mm I.D. x 50 mm, Zorbax C(18)) increased the sensitivity by a factor of approximately 100, when injecting the same mass of analyte. Incorporating an easily automated C(18) reversed phase column switching system with SPE (1.0mm I.D. x 5.0mm, 5 microm) made it possible to inject up to 100 microL of solution, and the total analysis time was 5.5 min.

A complex study of 5-amino-3-methyl-4-[2-(5-amino-1,3,4-oxadiazolo)]-isoxazole monohydrate: A new low-molecular-weight immune response modifier

NASA Astrophysics Data System (ADS)

Ryng, Stanisław; Zimecki, Michał; Jezierska-Mazzarello, Aneta; Panek, Jarosław J.; Mączyński, Marcin; Głowiak, Tadeusz; Sawka-Dobrowolska, Wanda; Koll, Aleksander

2011-07-01

A new potential lead structure with immunological activity, 5-amino-3-methyl-4-[2-(5-amino-1,3,4-oxadiazolo)]-isoxazole monohydrate, was synthesized. A detailed description of synthesis is presented together with X-ray structural analysis. In vitro assays showed that the compound had a potent immunosuppressive activity. Next, Density Functional Theory (DFT) was employed to shed a light on molecular properties of the investigated isoxazole derivative. The molecular modeling part included geometric as well as electronic structure descriptions: (i) the conformational analysis was performed to localize the most appropriate conformation; (ii) the coordination energy and Basis Set Superposition Error (BSSE) were estimated for the complex of the isoxazole derivative interacting with water molecule; (iii) the potential energy distribution was used to assign molecular vibrations, and NBO population analysis served to describe the electronic structure; (iv) the electrostatic potential map was generated to provide the graphical presentation of regions exposed for intermolecular interactions. The contacts between the water molecule and the nitrogen atom of the isoxazole ring edge were present in the solid phase. On the other hand, the theoretical DFT prediction was that the oxygen atom of the edge should form a more stable complex with the water molecule.

Extracellular micro and nanostructures forming the velvet worm solidified adhesive secretion

NASA Astrophysics Data System (ADS)

Corrales-Ureña, Yendry Regina; Sanchez, Angie; Pereira, Reinaldo; Rischka, Klaus; Kowalik, Thomas; Vega-Baudrit, José

2017-12-01

The onychophoran Epiperipatus hilkae secrets a sticky slime that solidifies almost immediately upon contact with air and under high humidy environmental condition forming a glassy like material. The general adhesive biochemical composition, the releasing and hardening mechanism have been partially described in literature. In this study, the structural characterization of the extracellular microstructures and nanostructures forming the solid adhesive of the secretion from Epiperipatus hilkae velvet worm is presented. The adhesive secretion is formed by macro-threads, which, in their solid state, are composed of globular particles approximately 700 nm in diameter that are distributed homogeneously throughout the matrix surface, and nanoparticles approximately 70 nm in diameter that and 6 nm in height self-assemble forming fiber-like structures. Nanoparticules with approximately 2 nm heights and others with non roundish forms are also observed. These 70 nm nano particles could be associated to proteins that form high density coverage films with low roughness; suggesting the formation of 2D ordered films. A crystalline and an amorphous phase composes the solidified secretion. The glassy or viscoelastic properties depend on the time in contact with air before being adhered to a solid surface and/or the mechanical stimulus; suggesting a key role of the drying on the hardening process.

Interface dynamics and crystal phase switching in GaAs nanowires

NASA Astrophysics Data System (ADS)

Jacobsson, Daniel; Panciera, Federico; Tersoff, Jerry; Reuter, Mark C.; Lehmann, Sebastian; Hofmann, Stephan; Dick, Kimberly A.; Ross, Frances M.

2016-03-01

Controlled formation of non-equilibrium crystal structures is one of the most important challenges in crystal growth. Catalytically grown nanowires are ideal systems for studying the fundamental physics of phase selection, and could lead to new electronic applications based on the engineering of crystal phases. Here we image gallium arsenide (GaAs) nanowires during growth as they switch between phases as a result of varying growth conditions. We find clear differences between the growth dynamics of the phases, including differences in interface morphology, step flow and catalyst geometry. We explain these differences, and the phase selection, using a model that relates the catalyst volume, the contact angle at the trijunction (the point at which solid, liquid and vapour meet) and the nucleation site of each new layer of GaAs. This model allows us to predict the conditions under which each phase should be observed, and use these predictions to design GaAs heterostructures. These results could apply to phase selection in other nanowire systems.

Interface dynamics and crystal phase switching in GaAs nanowires.

PubMed

Jacobsson, Daniel; Panciera, Federico; Tersoff, Jerry; Reuter, Mark C; Lehmann, Sebastian; Hofmann, Stephan; Dick, Kimberly A; Ross, Frances M

2016-03-17

Controlled formation of non-equilibrium crystal structures is one of the most important challenges in crystal growth. Catalytically grown nanowires are ideal systems for studying the fundamental physics of phase selection, and could lead to new electronic applications based on the engineering of crystal phases. Here we image gallium arsenide (GaAs) nanowires during growth as they switch between phases as a result of varying growth conditions. We find clear differences between the growth dynamics of the phases, including differences in interface morphology, step flow and catalyst geometry. We explain these differences, and the phase selection, using a model that relates the catalyst volume, the contact angle at the trijunction (the point at which solid, liquid and vapour meet) and the nucleation site of each new layer of GaAs. This model allows us to predict the conditions under which each phase should be observed, and use these predictions to design GaAs heterostructures. These results could apply to phase selection in other nanowire systems.

The LabTube - a novel microfluidic platform for assay automation in laboratory centrifuges.

PubMed

Kloke, A; Fiebach, A R; Zhang, S; Drechsel, L; Niekrawietz, S; Hoehl, M M; Kneusel, R; Panthel, K; Steigert, J; von Stetten, F; Zengerle, R; Paust, N

2014-05-07

Assay automation is the key for successful transformation of modern biotechnology into routine workflows. Yet, it requires considerable investment in processing devices and auxiliary infrastructure, which is not cost-efficient for laboratories with low or medium sample throughput or point-of-care testing. To close this gap, we present the LabTube platform, which is based on assay specific disposable cartridges for processing in laboratory centrifuges. LabTube cartridges comprise interfaces for sample loading and downstream applications and fluidic unit operations for release of prestored reagents, mixing, and solid phase extraction. Process control is achieved by a centrifugally-actuated ballpen mechanism. To demonstrate the workflow and functionality of the LabTube platform, we show two LabTube automated sample preparation assays from laboratory routines: DNA extractions from whole blood and purification of His-tagged proteins. Equal DNA and protein yields were observed compared to manual reference runs, while LabTube automation could significantly reduce the hands-on-time to one minute per extraction.

Synthesis and characterization of a Eu-DTPA-PEGO-MSH(4) derivative for evaluation of binding of multivalent molecules to melanocortin receptors.

PubMed

Xu, Liping; Vagner, Josef; Alleti, Ramesh; Rao, Venkataramanarao; Jagadish, Bhumasamudram; Morse, David L; Hruby, Victor J; Gillies, Robert J; Mash, Eugene A

2010-04-15

A labeled variant of MSH(4), a tetrapeptide that binds to the human melanocortin 4 receptor (hMC4R) with low microM affinity, was prepared by solid-phase synthesis methods, purified, and characterized. The labeled ligand, Eu-DTPA-PEGO-His-dPhe-Arg-Trp-NH(2), exhibited a K(d) for hMC4R of 9.1+/-1.4 microM, approximately 10-fold lower affinity than the parental ligand. The labeled MSH(4) derivative was employed in a competitive binding assay to characterize the interactions of hMC4R with monovalent and divalent MSH(4) constructs derived from squalene. The results were compared with results from a similar assay that employed a more potent labeled ligand, Eu-DTPA-NDP-alpha-MSH. While results from the latter assay reflected only statistical effects, results from the former assay reflected a mixture of statistical, proximity, and/or cooperative binding effects. Copyright 2010 Elsevier Ltd. All rights reserved.

Simultaneous determination of five systemic azoles in plasma by high-performance liquid chromatography with ultraviolet detection.

PubMed

Gordien, Jean-Baptiste; Pigneux, Arnaud; Vigouroux, Stephane; Tabrizi, Reza; Accoceberry, Isabelle; Bernadou, Jean-Marc; Rouault, Audrey; Saux, Marie-Claude; Breilh, Dominique

2009-12-05

A simple, specific and automatable HPLC assay was developed for a simultaneous determination of systemic azoles (fluconazole, posaconazole, voriconazole, itraconazole and its metabolite hydroxyl-itraconazole, and ketoconazole) in plasma. The major advantage of this assay was sample preparation by a fully automatable solid phase extraction with Varian Plexa cartridges. C6-phenyl column was used for chromatographic separation, and UV detection was set at a wavelength of 260 nm. Linezolid was used as an internal standard. The assay was specific and linear over the concentration range of 0.05 to 40 microg/ml excepted for fluconazole which was between 0.05 and 100 microg/ml, and itraconazole between 0.1 and 40 microg/ml. Validation data for accuracy and precision for intra- and inter-day were good and satisfied FDA's guidance: CV between 0.24% and 11.66% and accuracy between 93.8% and 108.7% for all molecules. This assay was applied to therapeutic drug monitoring on patients hospitalized in intensive care and onco-hematologic units.

Recombinant blood group proteins for use in antibody screening and identification tests.

PubMed

Seltsam, Axel; Blasczyk, Rainer

2009-11-01

The present review elucidates the potentials of recombinant blood group proteins (BGPs) for red blood cell (RBC) antibody detection and identification in pretransfusion testing and the achievements in this field so far. Many BGPs have been eukaryotically and prokaryotically expressed in sufficient quantity and quality for RBC antibody testing. Recombinant BGPs can be incorporated in soluble protein reagents or solid-phase assays such as ELISA, color-coded microsphere and protein microarray chip-based techniques. Because novel recombinant protein-based assays use single antigens, a positive reaction of a serum with the recombinant protein directly indicates the presence and specificity of the target antibody. Inversely, conventional RBC-based assays use panels of human RBCs carrying a huge number of blood group antigens at the same time and require negative reactions of samples with antigen-negative cells for indirect determination of antibody specificity. Because of their capacity for single-step, direct RBC antibody determination, recombinant protein-based assays may greatly facilitate and accelerate the identification of common and rare RBC antibodies.

Inventions leading to the development of the diagnostic test kit industry--from the modern pregnancy test to the sandwich assays.

PubMed

Wide, Leif

2005-01-01

The universities are encouraged by the government nowadays to stimulate innovations and also to provide the proper machinery for assisting the protection and commercialisation of innovations. A better understanding of the innovation process may help to create an atmosphere suitable for inventions at the university. Examples can be taken from successful innovations previously made at the university. During the 1960's I made a series of inventions, which ultimately led to the development of the diagnostic test kit industry. The first, which I made as an undergraduate, was a simple and reliable test kit for diagnosis of pregnancy. This was followed by the solid phase radioimmunoassay and a solid phase assay for vitamin B12; next, the dual specific non-competitive sandwich assay and the in-vitro test for diagnosis of allergy, called RAST (Radioallergosorbent test). Organon in Holland with the pregnancy test kit, and Pharmacia in Sweden with test kits for radioimmunoassay, became pioneers among the diagnostic test kit industries. Pharmacia Diagnostics later became one of the leading diagnostic test kit companies in the world and has continued to be so in the field of allergy diagnosis. Each one of these inventions started with a few unique observations leading to a technical development. The pregnancy test as well as the allergy test emerged from the development of assay methods with unique qualities with the subsequent search for appropriate applications. The foreseeing of a commercial value on a future market was a very important step. This was followed by the search for a suitable industry interested to exploit the invention with its new business opportunity i.e. apply for a patent, produce and market the products, which in my case consisted of the necessary reagents and equipments for particular diagnostic tests. Finally, an agreement had to be settled between the entrepreneur and the inventors. This report describes these inventions and particularly discusses some crucial steps of the innovation processes.

Liquid Adsorption of Organic Compounds on Hematite α-Fe2O3 Using ReaxFF.

PubMed

Chia, Chung-Lim; Avendaño, Carlos; Siperstein, Flor R; Filip, Sorin

2017-10-24

ReaxFF-based molecular dynamics simulations are used in this work to study the effect of the polarity of adsorbed molecules in the liquid phase on the structure and polarization of hematite (α-Fe 2 O 3 ). We compared the adsorption of organic molecules with different polarities on a rigid hematite surface and on a flexible and polarizable surface. We show that the displacements of surface atoms and surface polarization in a flexible hematite model are proportional to the adsorbed molecule's polarity. The increase in electrostatic interactions resulting from charge transfer in the outermost solid atoms in a flexible hematite model results in better-defined adsorbed layers that are less ordered than those obtained assuming a rigid solid. These results suggest that care must be taken when parametrizing empirical transferable force fields because the calculated charges on a solid slab in vacuum may not be representative of a real system, especially when the solid is in contact with a polar liquid.

Contact solution algorithms

NASA Technical Reports Server (NTRS)

Tielking, John T.

1989-01-01

Two algorithms for obtaining static contact solutions are described in this presentation. Although they were derived for contact problems involving specific structures (a tire and a solid rubber cylinder), they are sufficiently general to be applied to other shell-of-revolution and solid-body contact problems. The shell-of-revolution contact algorithm is a method of obtaining a point load influence coefficient matrix for the portion of shell surface that is expected to carry a contact load. If the shell is sufficiently linear with respect to contact loading, a single influence coefficient matrix can be used to obtain a good approximation of the contact pressure distribution. Otherwise, the matrix will be updated to reflect nonlinear load-deflection behavior. The solid-body contact algorithm utilizes a Lagrange multiplier to include the contact constraint in a potential energy functional. The solution is found by applying the principle of minimum potential energy. The Lagrange multiplier is identified as the contact load resultant for a specific deflection. At present, only frictionless contact solutions have been obtained with these algorithms. A sliding tread element has been developed to calculate friction shear force in the contact region of the rolling shell-of-revolution tire model.

40 CFR 63.802 - Emission limits.

Code of Federal Regulations, 2010 CFR

2010-07-01

... emissions from contact adhesives by achieving a VHAP limit for contact adhesives based on the following criteria: (i) For foam adhesives (contact adhesives used for upholstery operations) used in products that... VHAP content of the adhesive shall not exceed 1.8 kg VHAP/kg solids (1.8 lb VHAP/lb solids), as applied...

Different Results of IgE Binding- and Crosslinking-Based Allergy Tests Caused by Allergen Immobilization.

PubMed

Okamoto-Uchida, Yoshimi; Nakamura, Ryosuke; Matsuzawa, Yumiko; Soma, Megumi; Kawakami, Hiroshi; Ishii-Watabe, Akiko; Nishimaki-Mogami, Tomoko; Teshima, Reiko; Saito, Yoshiro

2016-01-01

The physicochemical nature of allergen molecules differ from the liquid phase to the solid phase. However, conventional allergy tests are based on the detection of immunoglobulin (Ig)E binding to immobilized allergens. We recently developed an in vitro allergy testing method using a luciferase-reporting humanized rat mast cell line to detect IgE crosslinking-induced luciferase expression (EXiLE test). The aim of the present study was to evaluate the effects of antigen immobilization on the results of different in vitro allergy tests using two anti-ovalbumin (OVA) antibodies (Abs), E-C1 and E-G5, with different properties in the OVA-induced allergic reaction. Both Abs showed clear binding to OVA with an enzyme-linked immunosorbent assay and by BIAcore analysis. However, only E-C1 potentiated EXiLE response for the liquid-phase OVA. On the other hand, OVA immobilized on solid-phase induced EXiLE responses in both E-C1 Ab- and E-G5 Ab-sensitized mast cells. Western blotting of OVA indicated that E-C1 Ab binds both to OVA monomers and dimers, unlike E-G5 Ab, which probably binds only to the OVA dimer. These results suggest that antigen immobilization enhanced IgE crosslinking ability through multimerization of allergen molecules in the solid phase, resulting in an increase in false positives in IgE binding-based conventional in vitro allergy tests. These findings shed light on the physicochemical nature of antigens as an important factor for the development and evaluation of in vitro allergy tests and suggest that mast cell activation-based allergy testing with liquid-phase allergens is a promising strategy to evaluate the physiological interactions of IgE and allergens.

Quantitation of IgE antibody specific for ragweed and grass allergens: binding of radiolabeled allergens by solid-phase bond IgE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zeiss, C.R.; Levitz, D.; Suszko, I.M.

1978-08-01

IgE antibody specific for multiple allergens extracted from grass and ragweed pollens was measured by radioimmunoassay. The assay depends on the interaction between IgE antibody bound to a polystyrene solid phase, /sup 125/I-labeled grass allergens (GA), and ragweed allergens (RW). The binding of /sup 125/I RW by serum IgE antibody from 37 allergic patients ranged from 0.2 ng to 75 ng RW protein (P) bound per ml. This binding of /sup 125/I RW by patient's IgE was paralleled by their IgE binding of /sup 125/I antigen E (AgE), a purified allergen from ragweed pollen (r = 0.90, p less thanmore » 0.001). Inhibition of patient's IgE binding of /sup 125/I RW by highly purified AgE ranged from 25 to 85% indicated individual differences in patient's IgE response to inhaled ragweed pollen. The binding of /sup 125/I GA by serum IgE antibody from 7 grass-sensitive patients ranged from 0.6 ng GA P bound per ml to 15 ng. This assay should be useful in the study of IgE responses to environmental agents containing multiple allergens and has the advantage that other antibody classes cannot interfere with the interaction between IgE antibody and labeled allergens.« less

Determination of cocaine, benzoylecgonine, cocaethylene and norcocaine in human hair using solid-phase extraction and liquid chromatography with tandem mass spectrometric detection.

PubMed

Moore, Christine; Coulter, Cynthia; Crompton, Katherine

2007-11-15

A quantitative analytical procedure for the determination of cocaine, benzoylecgonine and cocaethylene and norcocaine in hair has been developed and validated. The hair samples were washed, incubated, and any drugs present were quantified using mixed mode solid-phase extraction and liquid chromatography with tandem mass spectrometric detection in positive atmospheric pressure chemical ionization mode. For confirmation, two transitions were monitored and one ion ratio was determined, which was within 20% of that of the known calibration standards. The monitoring of the qualifying transition and requirement for its presence within a specific ratio to the primary ion limited the sensitivity of the assay, particularly for benzoylecgonine, however, the additional confidence in the final result as well as forensic defensibility were considered to be of greater importance. Even with simultaneous monitoring, the concentrations proposed by the United States Federal guidelines for hair analysis were achieved. The limits of quantitation were 50 pg/mg; the limit of detection was 25 pg/mg. The intra-day precision of the assays at 100 pg/mg (n=5) was 1.3%, 8.1%, 0.8% and 0.4%; inter-day precision 4.8%, 9.2%, 15.7% and 12.6% (n=10) for cocaine, benzoylecgonine, cocaethylene and norcocaine, respectively. The methods were applied to both proficiency specimens and to samples obtained during research studies in the USA.

Leukotriene B4 catabolism: quantitation of leukotriene B4 and its omega-oxidation products by reversed-phase high-performance liquid chromatography.

PubMed

Shak, S

1987-01-01

LTB4 and its omega-oxidation products may be rapidly, sensitively, and specifically quantitated by the methods of solid-phase extraction and reversed-phase high-performance liquid chromatography (HPLC), which are described in this chapter. Although other techniques, such as radioimmunoassay or gas chromatography-mass spectrometry, may be utilized for quantitative analysis of the lipoxygenase products of arachidonic acid, only the technique of reversed-phase HPLC can quantitate as many as 10 metabolites in a single analysis, without prior derivatization. In this chapter, we also reviewed the chromatographic theory which we utilized in order to optimize reversed-phase HPLC analysis of LTB4 and its omega-oxidation products. With this information and a gradient HPLC system, it is possible for any investigator to develop a powerful assay for the potent inflammatory mediator, LTB4, or for any other lipoxygenase product of arachidonic acid.

Developing interface localized liquid dielectrophoresis for optical applications

NASA Astrophysics Data System (ADS)

McHale, Glen; Brown, Carl V.; Newton, Michael I.; Wells, Gary G.; Sampara, Naresh

2012-11-01

Electrowetting charges the solid-liquid interface to change the contact area of a droplet of a conducting liquid. It is a powerful technique used to create variable focus liquid lenses, electronic paper and other devices, but it depends upon ions within the liquid. Liquid dielectrophoresis (L-DEP) is a bulk force acting on the dipoles throughout a dielectric liquid and is not normally considered to be a localized effect acting at the interface between the liquid and a solid or other fluid. In this work, we show theoretically how non-uniform electric fields generated by interdigitated electrodes can effectively convert L-DEP into an interface localized form. We show that for droplets of sufficient thickness, the change in the cosine of the contact angle is proportional to the square of the applied voltage and so obeys a similar equation to that for electrowetting - this we call dielectrowetting. However, a major difference to electrowetting is that the strength of the effect is controlled by the electrode spacing and the liquid permittivity rather than the properties of an insulator in a sandwich structure. Experimentally, we show that that this dielectrowetting equation accurately describes the contact angle of a droplet of oil viewed across parallel interdigitated electrodes. Importantly, the induced spreading can be complete, such that contact angle saturation does not occur. We then show that for thin films, L-DEP can shape the liquid-air interface creating a spatially periodic wrinkle and that such a wrinkle can be used to create a voltage programmable phase diffraction grating.

Solid-Liquid Interface Thermal Resistance Affects the Evaporation Rate of Droplets from a Surface: A Study of Perfluorohexane on Chromium Using Molecular Dynamics and Continuum Theory.

PubMed

Han, Haoxue; Schlawitschek, Christiane; Katyal, Naman; Stephan, Peter; Gambaryan-Roisman, Tatiana; Leroy, Frédéric; Müller-Plathe, Florian

2017-05-30

We study the role of solid-liquid interface thermal resistance (Kapitza resistance) on the evaporation rate of droplets on a heated surface by using a multiscale combination of molecular dynamics (MD) simulations and analytical continuum theory. We parametrize the nonbonded interaction potential between perfluorohexane (C 6 F 14 ) and a face-centered-cubic solid surface to reproduce the experimental wetting behavior of C 6 F 14 on black chromium through the solid-liquid work of adhesion (quantity directly related to the wetting angle). The thermal conductances between C 6 F 14 and (100) and (111) solid substrates are evaluated by a nonequilibrium molecular dynamics approach for a liquid pressure lower than 2 MPa. Finally, we examine the influence of the Kapitza resistance on evaporation of droplets in the vicinity of a three-phase contact line with continuum theory, where the thermal resistance of liquid layer is comparable with the Kapitza resistance. We determine the thermodynamic conditions under which the Kapitza resistance plays an important role in correctly predicting the evaporation heat flux.

TRALI ASSOCIATED HNA-3a ANTIBODIES RECOGNIZE COMPLEX DETERMINANTS ON CHOLINE TRANSPORTER-LIKE PROTEIN 2 (CTL2)

PubMed Central

Bougie, Daniel W; Peterson, Julie A; Kanack, Adam J; Curtis, Brian R; Aster, Richard H

2014-01-01

Background HNA-3a specific antibodies can cause severe, sometimes fatal, transfusion related acute lung injury (TRALI) when present in transfused blood. The HNA3-a/b antigens are determined by an R154Q polymorphism in the first of five extracellular loops of the 10-membrane spanning choline transporter-like protein 2 (CTL2) expressed on neutrophils, lymphocytes and other tissues. About 50% of HNA-3a antibodies (Type 1) can be detected using CTL2 Loop 1 peptides containing R154; the remaining 50% (Type 2) fail to recognize this target. Understanding the basis for this difference could guide efforts to develop practical assays to screen blood donors for HNA-3 antibodies. Study design and methods Reactions of HNA-3a antibodies against recombinant versions of human, mouse, and human/mouse (chimeric) CTL2 were characterized using flow cytometry and various solid phase assays. Results Findings made show that, for binding to CTL2, Type 2 HNA-3a antibodies require non-polymorphic amino acid residues in the third, and possibly the second, extracellular loops of CTL2 to be in a configuration comparable to that found naturally in the cell membrane. In contrast, Type 1 antibodies require only peptides from the first extracellular loop that contain R154 for recognition. Conclusion Although Type 1 HNA-3a antibodies can readily be detected in solid phase assays that use a CTL2 peptide containing R154 as a target, development of a practical test to screen blood donors for Type 2 antibodies will pose a serious technical challenge because of the complex nature of the epitope(s) recognized by this antibody sub-group. PMID:24846273

CH4 Hydrate Formation between Silica and Graphite Surfaces: Insights from Microsecond Molecular Dynamics Simulations.

PubMed

He, Zhongjin; Linga, Praveen; Jiang, Jianwen

2017-10-31

Microsecond simulations have been performed to investigate CH 4 hydrate formation from gas/water two-phase systems between silica and graphite surfaces, respectively. The hydrophilic silica and hydrophobic graphite surfaces exhibit substantially different effects on CH 4 hydrate formation. The graphite surface adsorbs CH 4 molecules to form a nanobubble with a flat or negative curvature, resulting in a low aqueous CH 4 concentration, and hydrate nucleation does not occur during 2.5 μs simulation. Moreover, an ordered interfacial water bilayer forms between the nanobubble and graphite surface thus preventing their direct contact. In contrast, the hydroxylated-silica surface prefers to be hydrated by water, with a cylindrical nanobubble formed in the solution, leading to a high aqueous CH 4 concentration and hydrate nucleation in the bulk region; during hydrate growth, the nanobubble is gradually covered by hydrate solid and separated from the water phase, hence slowing growth. The silanol groups on the silica surface can form strong hydrogen bonds with water, and hydrate cages need to match the arrangements of silanols to form more hydrogen bonds. At the end of the simulation, the hydrate solid is separated from the silica surface by liquid water, with only several cages forming hydrogen bonds with the silica surface, mainly due to the low CH 4 aqueous concentrations near the surface. To further explore hydrate formation between graphite surfaces, CH 4 /water homogeneous solution systems are also simulated. CH 4 molecules in the solution are adsorbed onto graphite and hydrate nucleation occurs in the bulk region. During hydrate growth, the adsorbed CH 4 molecules are gradually converted into hydrate solid. It is found that the hydrate-like ordering of interfacial water induced by graphite promotes the contact between hydrate solid and graphite. We reveal that the ability of silanol groups on silica to form strong hydrogen bonds to stabilize incipient hydrate solid, as well as the ability of graphite to adsorb CH 4 molecules and induce hydrate-like ordering of the interfacial water, are the key factors to affect CH 4 hydrate formation between silica and graphite surfaces.

Normal Forces at Solid-Liquid Interface

NASA Astrophysics Data System (ADS)

Das, Ratul

Adhesion can be defined as the tendency of dissimilar particles or surfaces to cling on to one another. Fields that require knowledge about adhesion interactions at the solid-liquid interface span over a wide spectrum from biotechnological issues such as liquid adhesion to skin tissues, insect feet adhesion to solids, or contact lenses to tear fluid adhesion; filtration issues such as membrane fouling and membrane affinity to different liquids; oil and gas extraction where one needs knowledge of the adhesion of the oil and brine to the rock; fuel cells in which droplets are formed on the electrodes and need to be considered in the system's design; classic chemical engineering industry such as drop adhesion to the mist eliminators in flash drums, or to heat exchangers; and classic surface science such as nano-structured surfaces, self cleaning surfaces, and general wetting phenomena. We execute the Young-Dupre (Y-P) gedanken experiment to establish unique values of work of adhesion rather than a work of adhesion range that the contact angle hysteresis results in. We use the Centrifugal Adhesion Balance (CAB) which allows independent manipulation of normal and lateral forces to induce an increase in the normal force which pulls on a liquid drop while keeping zero lateral force. This method mimics a drop that is subjected to a gravitational force that is gradually increasing. The values obtained for the work of adhesion are independent of drop size and are in agreement with the Y-P estimate. Cyclically varying the normal force, just to prevent the drop flying away from the surface will also enable us to study the Contact Angle Hysteresis for a pendant drop. With this set up, the work of adhesion is not only calculated from experimental normal force measurements, but the found results are also used to provide a venue for calculating the Young equilibrium contact angle, theta0. According to Shanahan and de Gennes, a liquid drop with a non-zero contact angle is associated with a deformation of the solid surface at the three phase contact line, causing the triple line to protrude up and form a rim, this is due to the unsatisfied normal component of the surface tension. Such rims were demonstrated by Care et al, and by Extrand, and the stresses associated with the rims facilitate reorientation of solid molecules at the interface, and therefore result in stronger solid liquid interaction at the rim. This stronger interaction gives rise to retention forces (due to adhesion). Recently, Xu et al, wrote a force equation based on this understanding, we test the validity of this approach and the Furmidge - Dussan model and other, more empirical, retention force approaches. A liquid drop that partially wets a solid surface will slide along the plane when a force beyond a critical value is applied to it. We study the sliding pattern of such a drop. Experiments for identifying the pattern of motion of liquid drops under influence of different normal forces are performed. We use a centrifugal adhesion balance (CAB) to study the pattern of drop motion under different effective gravities. A drop on a solid surface only slides after a certain critical force is applied to it, which is dependent on the drop volume, surface heterogeneities and other factors, even after the application of force the drop doesn't continue to move uniformly, which is the subject matter of this discussion.

Hysteresis of Contact Angle of Sessile Droplets on Smooth Homogeneous Solid Substrates via Disjoining/Conjoining Pressure.

PubMed

Kuchin, I; Starov, V

2015-05-19

A theory of contact angle hysteresis of liquid droplets on smooth, homogeneous solid substrates is developed in terms of the shape of the disjoining/conjoining pressure isotherm and quasi-equilibrium phenomena. It is shown that all contact angles, θ, in the range θr < θ < θa, which are different from the unique equilibrium contact angle θ ≠ θe, correspond to the state of slow "microscopic" advancing or receding motion of the liquid if θe < θ < θa or θr < θ < θe, respectively. This "microscopic" motion almost abruptly becomes fast "macroscopic" advancing or receding motion after the contact angle reaches the critical values θa or θr, correspondingly. The values of the static receding, θr, and static advancing, θa, contact angles in cylindrical capillaries were calculated earlier, based on the shape of disjoining/conjoining pressure isotherm. It is shown now that (i) both advancing and receding contact angles of a droplet on a on smooth, homogeneous solid substrate can be calculated based on shape of disjoining/conjoining pressure isotherm, and (ii) both advancing and receding contact angles depend on the drop volume and are not unique characteristics of the liquid-solid system. The latter is different from advancing/receding contact angles in thin capillaries. It is shown also that the receding contact angle is much closer to the equilibrium contact angle than the advancing contact angle. The latter conclusion is unexpected and is in a contradiction with the commonly accepted view that the advancing contact angle can be taken as the first approximation for the equilibrium contact angle. The dependency of hysteresis contact angles on the drop volume has a direct experimental confirmation.

Confirmatory and quantitative analysis of beta-lactam antibiotics in bovine kidney tissue by dispersive solid-phase extraction and liquid chromatography-tandem mass spectrometry.

PubMed

Fagerquist, Clifton K; Lightfield, Alan R; Lehotay, Steven J

2005-03-01

A simple, rapid, rugged, sensitive, and specific method for the confirmation and quantitation of 10 beta-lactam antibiotics in fortified and incurred bovine kidney tissue has been developed. The method uses a simple solvent extraction, dispersive solid-phase extraction (dispersive-SPE) cleanup, and liquid chromatography-tandem mass spectrometry (LC/MS/MS) for confirmation and quantitation. Dispersive-SPE greatly simplifies and accelerates sample cleanup and improves overall recoveries compared with conventional SPE cleanup. The beta-lactam antibiotics tested were as follows: deacetylcephapirin (an antimicrobial metabolite of cephapirin), amoxicillin, desfuroylceftiofur cysteine disulfide (DCCD, an antimicrobial metabolite of ceftiofur), ampicillin, cefazolin, penicillin G, oxacillin, cloxacillin, naficillin, and dicloxacillin. Average recoveries of fortified samples were 70% or better for all beta-lactams except DCCD, which had an average recovery of 58%. The LC/MS/MS method was able to demonstrate quantitative recoveries at established tolerance levels and provide confirmatory data for unambiguous analyte identification. The method was also tested on 30 incurred bovine kidney samples obtained from the USDA Food Safety and Inspection Service, which had previously tested the samples using the approved semiquantitative microbial assay. The results from the quantitative LC/MS/MS analysis were in general agreement with the microbial assay for 23 samples although the LC/MS/MS method was superior in that it could specifically identify which beta-lactam was present and quantitate its concentration, whereas the microbial assay could only identify the type of beta-lactam present and report a concentration with respect to the microbial inhibition of a penicillin G standard. In addition, for 6 of the 23 samples, LC/MS/MS analysis detected a penicillin and a cephalosporin beta-lactam, whereas the microbial assay detected only a penicillin beta-lactam. For samples that do not fall into the "general agreement" category, the most serious discrepancy involves two samples where the LC/MS/MS method detected a violative level of a cephalosporin beta-lactam (deacetylcephapirin) in the first sample and a possibly violative level of desfuroylceftiofur in the second, whereas the microbial assay identified the two samples as having only violative levels of a penicillin beta-lactam.

Weathering of phlogopite by Bacillus cereus and Acidithiobacillus ferrooxidans.

PubMed

Styriaková, Iveta; Bhatti, Tariq M; Bigham, Jerry M; Styriak, Igor; Vuorinen, Antti; Tuovinen, Olli H

2004-03-01

The purpose of this study was to assess the weathering of finely ground phlogopite, a trioctahedral mica, by placing it in contact with heterotrophic (Bacillus cereus) and acidophilic (Acidithiobacillus ferrooxidans) cultures. X-ray diffraction analyses of the phlogopite sample before and after 24 weeks of contact in B. cereus cultures revealed a decrease in the characteristic peak intensities of phlogopite, indicating destruction of individual structural planes of the mica. No new solid phase products or interlayer structures were detected in B. cereus cultures. Acidithiobacillus ferrooxidans cultures enhanced the chemical dissolution of the mineral and formed partially weathered interlayer structures, where interlayer K was expelled and coupled with the precipitation of K-jarosite [KFe3(SO4)2(OH)6].

Solid Phase Extraction of Inorganic Mercury Using 5-Phenylazo-8-hydroxyquinoline and Determination by Cold Vapor Atomic Fluorescence Spectroscopy in Natural Water Samples

PubMed Central

Daye, Mirna; Halwani, Jalal; Hamzeh, Mariam

2013-01-01

8-Hydroxyquinoline (8-HQ) was chosen as a powerful ligand for Hg solid phase extraction. Among several chelating resins based on 8-HQ, 5-phenylazo-8-hydroxyquinoline (5Ph8HQ) is used for mercury extraction in which the adsorption dynamics were fully studied. It has been shown that Hg(II) is totally absorbed by 5Ph8HQ within the first 30 minutes of contact time with t 1/2 5 minutes, following Langmuir adsorption model. At pH 4, the affinity of mercury is unchallenged by other metals except, for Cu(II), which have shown higher Kd value. With these latter characteristics, 5Ph8HQ was examined for the preconcentration of trace levels of Hg(II). The developed method showed quantitative recoveries of Hg(II) with LOD = 0.21 pg mL−1 and RSD = 3–6% using cold vapor atomic fluorescence spectroscopy (CV-AFS) with a preconcentration factor greater than 250. PMID:24459417

Automated solid-phase subcloning based on beads brought into proximity by magnetic force.

PubMed

Hudson, Elton P; Nikoshkov, Andrej; Uhlen, Mathias; Rockberg, Johan

2012-01-01

In the fields of proteomics, metabolic engineering and synthetic biology there is a need for high-throughput and reliable cloning methods to facilitate construction of expression vectors and genetic pathways. Here, we describe a new approach for solid-phase cloning in which both the vector and the gene are immobilized to separate paramagnetic beads and brought into proximity by magnetic force. Ligation events were directly evaluated using fluorescent-based microscopy and flow cytometry. The highest ligation efficiencies were obtained when gene- and vector-coated beads were brought into close contact by application of a magnet during the ligation step. An automated procedure was developed using a laboratory workstation to transfer genes into various expression vectors and more than 95% correct clones were obtained in a number of various applications. The method presented here is suitable for efficient subcloning in an automated manner to rapidly generate a large number of gene constructs in various vectors intended for high throughput applications.

Fabrication of a Dipole-assisted Solid Phase Extraction Microchip for Trace Metal Analysis in Water Samples

PubMed Central

Chen, Ping-Hung; Chen, Shun-Niang; Tseng, Sheng-Hao; Deng, Ming-Jay; Lin, Yang-Wei; Sun, Yuh-Chang

2016-01-01

This paper describes a fabrication protocol for a dipole-assisted solid phase extraction (SPE) microchip available for trace metal analysis in water samples. A brief overview of the evolution of chip-based SPE techniques is provided. This is followed by an introduction to specific polymeric materials and their role in SPE. To develop an innovative dipole-assisted SPE technique, a chlorine (Cl)-containing SPE functionality was implanted into a poly(methyl methacrylate) (PMMA) microchip. Herein, diverse analytical techniques including contact angle analysis, Raman spectroscopic analysis, and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis were employed to validate the utility of the implantation protocol of the C-Cl moieties on the PMMA. The analytical results of the X-ray absorption near-edge structure (XANES) analysis also demonstrated the feasibility of the Cl-containing PMMA used as an extraction medium by virtue of the dipole-ion interactions between the highly electronegative C-Cl moieties and the positively charged metal ions. PMID:27584954

Automated Solid-Phase Subcloning Based on Beads Brought into Proximity by Magnetic Force

PubMed Central

Hudson, Elton P.; Nikoshkov, Andrej; Uhlen, Mathias; Rockberg, Johan

2012-01-01

In the fields of proteomics, metabolic engineering and synthetic biology there is a need for high-throughput and reliable cloning methods to facilitate construction of expression vectors and genetic pathways. Here, we describe a new approach for solid-phase cloning in which both the vector and the gene are immobilized to separate paramagnetic beads and brought into proximity by magnetic force. Ligation events were directly evaluated using fluorescent-based microscopy and flow cytometry. The highest ligation efficiencies were obtained when gene- and vector-coated beads were brought into close contact by application of a magnet during the ligation step. An automated procedure was developed using a laboratory workstation to transfer genes into various expression vectors and more than 95% correct clones were obtained in a number of various applications. The method presented here is suitable for efficient subcloning in an automated manner to rapidly generate a large number of gene constructs in various vectors intended for high throughput applications. PMID:22624028

Process for separating dissolved solids from a liquid using an anti-solvent and multiple effect evaporators

DOEpatents

Daniels, Edward J.; Jody, Bassam J.; Bonsignore, Patrick V.

1994-01-01

A process and system for treating aluminum salt cake containing water soluble halide salts by contacting the salt cake with water to dissolve water soluble halide salts forming a saturated brine solution. Transporting a portion of about 25% of the saturated brine solution to a reactor and introducing into the saturated brine solution at least an equal volume of a water-miscible low-boiling organic material such as acetone to precipitate a portion of the dissolved halide salts forming a three-phase mixture of an aqueous-organic-salt solution phase and a precipitated salt phase and an organic rich phase. The precipitated salt phase is separated from the other phases and the organic rich phase is recycled to the reactor. The remainder of the saturated brine solution is sent to a multiple effect evaporator having a plurality of stages with the last stage thereof producing low grade steam which is used to boil off the organic portion of the solution which is recycled.

Process for separating dissolved solids from a liquid using an anti-solvent and multiple effect evaporators

DOEpatents

Daniels, E.J.; Jody, B.J.; Bonsignore, P.V.

1994-07-19

A process and system are disclosed for treating aluminum salt cake containing water soluble halide salts by contacting the salt cake with water to dissolve water soluble halide salts forming a saturated brine solution. Transporting a portion of about 25% of the saturated brine solution to a reactor and introducing into the saturated brine solution at least an equal volume of a water-miscible low-boiling organic material such as acetone to precipitate a portion of the dissolved halide salts forming a three-phase mixture of an aqueous-organic-salt solution phase and a precipitated salt phase and an organic rich phase. The precipitated salt phase is separated from the other phases and the organic rich phase is recycled to the reactor. The remainder of the saturated brine solution is sent to a multiple effect evaporator having a plurality of stages with the last stage thereof producing low grade steam which is used to boil off the organic portion of the solution which is recycled. 3 figs.

A sensitive high-pressure liquid chromatography/particle beam/mass spectrometry assay for the determination of all-trans-retinoic acid and 13-cis-retinoic acid in human plasma.

PubMed

Lehman, P A; Franz, T J

1996-03-01

A highly sensitive assay for the measurement of all-trans-retinoic acid (tretinoin) and 13-cis-retinoic acid (isotretinoin) has been developed. Collected plasma samples were protein precipitated with 2-propanol followed by solid phase extraction. The retinoic acids were subsequently derivatized to their pentafluorobenzyl esters followed by separation and isolation by reverse phase high-pressure liquid chromatography. The HPLC eluate was directed to a mass spectrometer via a particle beam interface. Selected ion monitoring (299 m/z) for the retinoic acid's carboxylate anion produced by negative chemical ionization using methane reagent gas achieved minimum detection limits of 25 pg injected. Endogenous blood levels in 19 male and 9 female subjects were measured. It was found that females have significantly more all-trans-retinoic acid than males and that both sexes demonstrate significantly more all-trans-retinoic acid then 13-cis-retinoic acid.

Functional nucleic acid entrapment in sol-gel derived materials.

PubMed

Carrasquilla, Carmen; Brennan, John D

2013-10-01

Functional nucleic acids (FNAs) are single-stranded DNA or RNA molecules, typically generated through in vitro selection, that have the ability to act as receptors for target molecules (aptamers) or perform catalysis of a chemical reaction (deoxyribozymes and ribozymes). Fluorescence-signaling aptamers and deoxyribozymes have recently emerged as promising biological recognition and signaling elements, although little has been done to evaluate their potential for solid-phase assays, particularly with species made of RNA due to their lack of chemical stability and susceptibility to nuclease attack. Herein, we present a detailed overview of the methods utilized for solid-phase immobilization of FNAs using a sol-gel entrapment method that can provide protection from nuclease degradation and impart long-term chemical stability to the FNA reporter systems, while maintaining their signaling capabilities. This article will also provide a brief review of the results of such entrapment studies involving fluorescence-signaling versions of a DNA aptamer, selected RNA-cleaving deoxyribozymes, and two different RNA aptamers in a series of sol-gel derived composites, ranging from highly polar silica to hydrophobic methylsilsesquioxane-based materials. Given the ability to produce sol-gel derived materials in a variety of configurations, particularly as thin film coatings on electrodes, optical fibers, and other devices, this entrapment method should provide a useful platform for numerous solid-phase FNA-based biosensing applications. Copyright © 2013 Elsevier Inc. All rights reserved.

Development and utilization of new diagnostics for dense-phase pneumatic transport

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

Dense-phase pneumatic transport is an attractive means of conveying solids. Unfortunately, because of the high solid concentrations, this transport method is a difficult regime in which to carry out detailed measurements. Hence most details of the flow are unknown. In this context, the main objective of this work is to develop probes for local measurements of solid velocity and holdup in dense gas-solid flows. Because we anticipate the recent theories of rapid granular flows will bring insight to the dense pneumatic transport of particles, we have sought to substantiate these theories through computer simulations. There we have verified the theorymore » of Hanes, Jenkins Richman (1988) for the rapid, steady shear flow of identical, smooth, nearly elastics disks driven by identical, parallel, bumpy boundaries. Because granular flows depend strongly on the nature of their interaction with a boundary, we have verified the boundary conditions calculated by Jenkins (1991) for spheres interacting with a flat, frictional surface. During the previous reporting period, we began a study of the time relaxation of the second moment of velocity fluctuations for a collection of disks undergoing simple shear. In the present reporting period, we have completed this study of relaxation by comparing results of simulations with the theoretical predictions of Jenkins and Richman (1988). In addition, we have concluded a series of experiments with flour plugs in the dense-phase pneumatic setup. Finally, we have established several industrial contacts to transfer the diagnostic techniques developed under this contract. 7 refs., 11 figs.« less

Two dimensional modeling of elastic wave propagation in solids containing cracks with rough surfaces and friction - Part I: Theoretical background.

PubMed

Aleshin, Vladislav; Delrue, Steven; Trifonov, Andrey; Bou Matar, Olivier; Van Den Abeele, Koen

2018-01-01

Our study aims at the creation of a numerical toolbox that describes wave propagation in samples containing internal contacts (e.g. cracks, delaminations, debondings, imperfect intergranular joints) of known geometry with postulated contact interaction laws including friction. The code consists of two entities: the contact model and the solid mechanics module. Part I of the paper concerns the modeling of internal contacts (called cracks for brevity), while part II is related to the integration of the developed contact model into a solid mechanics module that allows the description of wave propagation processes. The contact model is used to produce normal and tangential load-displacement relationships, which in turn are used by the solid mechanics module as boundary conditions at the internal contacts. Due to friction, the tangential reaction curve is hysteretic and memory-dependent. In addition, it depends on the normal reaction curve. An essential feature of the proposed contact model is that it takes into account the roughness of the contact faces. On one hand, accounting for roughness makes the contact model more complicated since it gives rise to a partial slip regime when some parts on the contact area experience slip and some do not. On the other hand, as we will show, the concept of contact surfaces covered by asperities receding under load makes it possible to formulate a consistent contact model that provides nonlinear load-displacement relationships for any value of the drive displacements and their histories. This is a strong advantage, since this way, the displacement-driven model allows for a simple explicit procedure of data exchange with the solid mechanics module, while more traditional flat-surface contacts driven by loads generate a complex iterative procedure. More specifically, the proposed contact model is based on the previously developed method of memory diagrams that allows one to automatically obtain memory-dependent solutions to frictional contact problems in the particular case of partial slip. Here we extend the solution onto cases of total sliding and contact loss which is possible while using the displacement-driven formulation. The method requires the knowledge of the normal contact response obtained in our case as a result of statistical consideration of roughness of contact faces. Copyright © 2017 Elsevier B.V. All rights reserved.

Enhanced oxygen reduction activity and solid oxide fuel cell performance with a nanoparticles-loaded cathode.

PubMed

Zhang, Xiaomin; Liu, Li; Zhao, Zhe; Tu, Baofeng; Ou, Dingrong; Cui, Daan; Wei, Xuming; Chen, Xiaobo; Cheng, Mojie

2015-03-11

Reluctant oxygen-reduction-reaction (ORR) activity has been a long-standing challenge limiting cell performance for solid oxide fuel cells (SOFCs) in both centralized and distributed power applications. We report here that this challenge has been tackled with coloading of (La,Sr)MnO3 (LSM) and Y2O3 stabilized zirconia (YSZ) nanoparticles within a porous YSZ framework. This design dramatically improves ORR activity, enhances fuel cell output (200-300% power improvement), and enables superior stability (no observed degradation within 500 h of operation) from 600 to 800 °C. The improved performance is attributed to the intimate contacts between nanoparticulate YSZ and LSM particles in the three-phase boundaries in the cathode.

Development and application of a sensitive, phenotypic, high-throughput image-based assay to identify compound activity against Trypanosoma cruzi amastigotes

PubMed Central

Sykes, Melissa L.; Avery, Vicky M.

2015-01-01

We have developed a high content 384-well, image-based assay to estimate the effect of compound treatment on Trypanosoma cruzi amastigotes in 3T3 fibroblasts. In the same well, the effect of compound activity on host cells can also be determined, as an initial indicator of cytotoxicity. This assay has been used to identify active compounds from an in-house library of compounds with either known biological activity or that are FDA approved, and separately, from the Medicines for Malaria Venture Malaria Box collection. Active compounds were screened against T. cruzi trypomastigotes, utilising an assay developed with the viability dye resazurin. Twelve compounds with reconfirmed solid sample activity, with IC50 values of less than 10 μM and selectivity indices to T. cruzi amastigotes over 3T3 host cells of between >22 and 319 times were identified from these libraries. As 3T3 cells are contact inhibited, with limited proliferation in the assay, selective compounds of interest were profiled in a separate assay to estimate the viability of compound treated, replicating HEK293 cells. Selective compounds that were not previously reported in the literature were further profiled by extending the incubation time against amastigote infected 3T3 cells to determine if there were residual amastigotes post-treatment, important for the consideration of the exposure time required for further biological characterisation. The assay development process and the suitability of identified compounds as hit molecules for Chagas disease research are discussed. PMID:27120069

Development and application of a sensitive, phenotypic, high-throughput image-based assay to identify compound activity against Trypanosoma cruzi amastigotes.

PubMed

Sykes, Melissa L; Avery, Vicky M

2015-12-01

We have developed a high content 384-well, image-based assay to estimate the effect of compound treatment on Trypanosoma cruzi amastigotes in 3T3 fibroblasts. In the same well, the effect of compound activity on host cells can also be determined, as an initial indicator of cytotoxicity. This assay has been used to identify active compounds from an in-house library of compounds with either known biological activity or that are FDA approved, and separately, from the Medicines for Malaria Venture Malaria Box collection. Active compounds were screened against T. cruzi trypomastigotes, utilising an assay developed with the viability dye resazurin. Twelve compounds with reconfirmed solid sample activity, with IC50 values of less than 10 μM and selectivity indices to T. cruzi amastigotes over 3T3 host cells of between >22 and 319 times were identified from these libraries. As 3T3 cells are contact inhibited, with limited proliferation in the assay, selective compounds of interest were profiled in a separate assay to estimate the viability of compound treated, replicating HEK293 cells. Selective compounds that were not previously reported in the literature were further profiled by extending the incubation time against amastigote infected 3T3 cells to determine if there were residual amastigotes post-treatment, important for the consideration of the exposure time required for further biological characterisation. The assay development process and the suitability of identified compounds as hit molecules for Chagas disease research are discussed. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Application of solid-phase microextraction in the investigation of protein binding of pharmaceuticals.

PubMed

Theodoridis, Georgios

2006-01-18

Protein-drug interactions of seven common pharmaceuticals were studied using solid-phase microextraction (SPME). SPME can be used in such investigations on the condition that no analyte depletion occurs. In multi-compartment systems (e.g. a proteinaceous matrix) only the free portion of the analyte is able to partition into the SPME fiber. In addition if no sample depletion occurs, the bound drug-free drug equilibria are not disturbed. In the present study seven pharmaceuticals (quinine, quinidine, naproxen, ciprofloxacin, haloperidol, paclitaxel and nortriptyline) were assayed by SPME. For quantitative purposes SPME was validated first in the absence of proteins. Calibration curves were constructed for each drug by HPLC-fluorescence and HPLC-UV analysis. SPME was combined to HPLC off-line, desorption occurring in HPLC inserts filled with 200 microL methanol. Binding of each drug to human serum albumin was studied independently. Experimental results were in agreement with literature data and ultrafiltration experiments, indicating the feasibility of the method for such bioanalytical purposes.

An Automated High-Throughput System to Fractionate Plant Natural Products for Drug Discovery

PubMed Central

Tu, Ying; Jeffries, Cynthia; Ruan, Hong; Nelson, Cynthia; Smithson, David; Shelat, Anang A.; Brown, Kristin M.; Li, Xing-Cong; Hester, John P.; Smillie, Troy; Khan, Ikhlas A.; Walker, Larry; Guy, Kip; Yan, Bing

2010-01-01

The development of an automated, high-throughput fractionation procedure to prepare and analyze natural product libraries for drug discovery screening is described. Natural products obtained from plant materials worldwide were extracted and first prefractionated on polyamide solid-phase extraction cartridges to remove polyphenols, followed by high-throughput automated fractionation, drying, weighing, and reformatting for screening and storage. The analysis of fractions with UPLC coupled with MS, PDA and ELSD detectors provides information that facilitates characterization of compounds in active fractions. Screening of a portion of fractions yielded multiple assay-specific hits in several high-throughput cellular screening assays. This procedure modernizes the traditional natural product fractionation paradigm by seamlessly integrating automation, informatics, and multimodal analytical interrogation capabilities. PMID:20232897

Method for removal and stabilization of mercury in mercury-containing gas streams

DOEpatents

Broderick, Thomas E.

2005-09-13

The present invention is directed to a process and apparatus for removing and stabilizing mercury from mercury-containing gas streams. A gas stream containing vapor phase elemental and/or speciated mercury is contacted with reagent, such as an oxygen-containing oxidant, in a liquid environment to form a mercury-containing precipitate. The mercury-containing precipitate is kept or placed in solution and reacts with one or more additional reagents to form a solid, stable mercury-containing compound.

Wetting Behavior in Colloid-Polymer Mixtures at Different Substrates.

PubMed

Wijting, Willem K; Besseling, Nicolaas A M; Cohen Stuart, Martien A

2003-09-25

We present experimental observations on wetting phenomena in depletion interaction driven, phase separated colloidal dispersions. The contact angle of the colloidal liquid-gas interface at a solid substrate was determined for a series of compositions. Upon approach to the critical point, a transition occurs from partial to complete wetting. The interaction with the substrate was manipulated by modifying the substrate with a polymer. In that case, a transition from partial to complete drying is observed upon approach to the critical point.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Raymond H.; Stone, James; Truax, Ryan

Batch tests, column tests, and predictive reactive transport modeling can be done before ISR begins as part of the decision making/permitting process by bracketing possible post-restoration conditions; Help address stakeholder concerns; The best predictions require actual restored groundwater in contact with the downgradient solid phase; Resulting modeling provides a range of natural attenuation rates and assists with designing the best locations and time frames for continued monitoring; Field pilot tests are the best field-scale data and can provide the best model input and calibration data

Development of an innovative immunoassay for CP4EPSPS and Cry1AB genetically modified protein detection and quantification.

PubMed

Ermolli, M; Prospero, A; Balla, B; Querci, M; Mazzeo, A; Van Den Eede, G

2006-09-01

An innovative immunoassay, called enzyme-linked immunoabsorbant assay (ELISA) Reverse, based on a new conformation of the solid phase, was developed. The solid support was expressly designed to be immersed directly in liquid samples to detect the presence of protein targets. Its application is proposed in those cases where a large number of samples have to be screened simultaneously or when the simultaneous detection of different proteins is required. As a first application, a quantitative immunoassay for Cry1AB protein in genetically modified maize was optimized. The method was tested using genetically modified organism concentrations from 0.1 to 2.0%. The limit of detection and limit of quantitation of the method were determined as 0.0056 and 0.0168 (expressed as the percentage of genetically modified organisms content), respectively. A qualitative multiplex assay to assess the presence of two genetically modified proteins simultaneously was also established for the case of the Cry1AB and the CP4EPSPS (5-enolpyruvylshikimate-3-phosphate synthase) present in genetically modified maize and soy, respectively.

Comparison of spray drying, electroblowing and electrospinning for preparation of Eudragit E and itraconazole solid dispersions.

PubMed

Sóti, Péter Lajos; Bocz, Katalin; Pataki, Hajnalka; Eke, Zsuzsanna; Farkas, Attila; Verreck, Geert; Kiss, Éva; Fekete, Pál; Vigh, Tamás; Wagner, István; Nagy, Zsombor K; Marosi, György

2015-10-15

Three solvent based methods: spray drying (SD), electrospinning (ES) and air-assisted electrospinning (electroblowing; EB) were used to prepare solid dispersions of itraconazole and Eudragit E. Samples with the same API/polymer ratios were prepared in order to make the three technologies comparable. The structure and morphology of solid dispersions were identified by scanning electron microscopy and solid phase analytical methods such as, X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC) and Raman chemical mapping. Moreover, the residual organic solvents of the solid products were determined by static headspace-gas chromatography/mass spectroscopy measurements and the wettability of samples was characterized by contact angle measurement. The pharmaceutical performance of the three dispersion type, evaluated by dissolution tests, proved to be very similar. According to XRPD and DSC analyses, made after the production, all the solid dispersions were free of any API crystal clusters but about 10 wt% drug crystallinity was observed after three months of storage in the case of the SD samples in contrast to the samples produced by ES and EB in which the polymer matrix preserved the API in amorphous state. Copyright © 2015 Elsevier B.V. All rights reserved.

Contact-angle hysteresis on periodic microtextured surfaces: Strongly corrugated liquid interfaces.

PubMed

Iliev, Stanimir; Pesheva, Nina

2016-06-01

We study numerically the shapes of a liquid meniscus in contact with ultrahydrophobic pillar surfaces in Cassie's wetting regime, when the surface is covered with identical and periodically distributed micropillars. Using the full capillary model we obtain the advancing and the receding equilibrium meniscus shapes when the cross-sections of the pillars are both of square and circular shapes, for a broad interval of pillar concentrations. The bending of the liquid interface in the area between the pillars is studied in the framework of the full capillary model and compared to the results of the heterogeneous approximation model. The contact angle hysteresis is obtained when the three-phase contact line is located on one row (block case) or several rows (kink case) of pillars. It is found that the contact angle hysteresis is proportional to the line fraction of the contact line on pillars tops in the block case and to the surface fraction for pillar concentrations 0.1-0.5 in the kink case. The contact angle hysteresis does not depend on the shape (circular or square) of the pillars cross-section. The expression for the proportionality of the receding contact angle to the line fraction [Raj et al., Langmuir 28, 15777 (2012)LANGD50743-746310.1021/la303070s] in the case of block depinning is theoretically substantiated through the capillary force, acting on the solid plate at the meniscus contact line.

Water-induced phase separation of miconazole-poly (vinylpyrrolidone-co-vinyl acetate) amorphous solid dispersions: Insights with confocal fluorescence microscopy.

PubMed

Saboo, Sugandha; Taylor, Lynne S

2017-08-30

The aim of this study was to evaluate the utility of confocal fluorescence microscopy (CFM) to study the water-induced phase separation of miconazole-poly (vinylpyrrolidone-co-vinyl acetate) (mico-PVPVA) amorphous solid dispersions (ASDs), induced during preparation, upon storage at high relative humidity (RH) and during dissolution. Different fluorescent dyes were added to drug-polymer films and the location of the dyes was evaluated using CFM. Orthogonal techniques, in particular atomic force microscopy (AFM) coupled with nanoscale infrared spectroscopy (AFM-nanoIR), were used to provide additional analysis of the drug-polymer blends. The initial miscibility of mico-PVPVA ASDs prepared under low humidity conditions was confirmed by AFM-nanoIR. CFM enabled rapid identification of drug-rich and polymer-rich phases in phase separated films prepared under high humidity conditions. The identity of drug- and polymer-rich domains was confirmed using AFM-nanoIR imaging and localized IR spectroscopy, together with Lorentz contact resonance (LCR) measurements. The CFM technique was then utilized successfully to further investigate phase separation in mico-PVPVA films exposed to high RH storage and to visualize phase separation dynamics following film immersion in buffer. CFM is thus a promising new approach to study the phase behavior of ASDs, utilizing drug and polymer specific dyes to visualize the evolution of heterogeneity in films exposed to water. Copyright © 2017 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Apel, William A; Thompson, Vicki S

A method for analyzing a biological sample by antibody profiling for identifying forensic samples or for detecting the presence of an analyte. In an embodiment of the invention, the analyte is a drug, such as marijuana, Cocaine (crystalline tropane alkaloid), methamphetamine, methyltestosterone, or mesterolone. The method comprises attaching antigens to a surface of a solid support in a preselected pattern to form an array wherein locations of the antigens are known; contacting the array with the biological sample such that a portion of antibodies in the sample reacts with and binds to the antigens in the array to form immunemore » complexes; washing away antibodies that do form immune complexes; and detecting the immune complexes, to form an antibody profile. Forensic samples are identified by comparing a sample from an unknown source with a sample from a known source. Further, an assay, such as a test for illegal drug use, can be coupled to a test for identity such that the results of the assay can be positively correlated to the subject's identity.« less

Antibody profiling sensitivity through increased reporter antibody layering

DOEpatents

Apel, William A.; Thompson, Vicki S.

2013-02-26

A method for analyzing a biological sample by antibody profiling for identifying forensic samples or for detecting the presence of an analyte. In an embodiment of the invention, the analyte is a drug, such as marijuana, Cocaine (crystalline tropane alkaloid), methamphetamine, methyltestosterone, or mesterolone. The method comprises attaching antigens to a surface of a solid support in a preselected pattern to form an array wherein locations of the antigens are known; contacting the array with the biological sample such that a portion of antibodies in the sample reacts with and binds to the antigens in the array to form immune complexes; washing away antibodies that do form immune complexes; and detecting the immune complexes, to form an antibody profile. Forensic samples are identified by comparing a sample from an unknown source with a sample from a known source. Further, an assay, such as a test for illegal drug use, can be coupled to a test for identity such that the results of the assay can be positively correlated to the subject's identity.

Rapid classification of biological components

DOEpatents

Thompson, Vicki S.; Barrett, Karen B.; Key, Diane E.

2013-10-15

A method is disclosed for analyzing a biological sample by antibody profiling for identifying forensic samples or for detecting the presence of an analyte. In an illustrative embodiment of the invention, the analyte is a drug, such as marijuana, cocaine (crystalline tropane alkaloid), methamphetamine, methyltestosterone, or mesterolone. The method involves attaching antigens to a surface of a solid support in a preselected pattern to form an array wherein the locations of the antigens are known; contacting the array with the biological sample such that a portion of antibodies in the sample reacts with and binds to antigens in the array, thereby forming immune complexes; washing away antibodies that do not form immune complexes; and detecting the immune complexes, thereby forming an antibody profile. Forensic samples are identified by comparing a sample from an unknown source with a sample from a known source. Further, an assay, such as a test for illegal drug use, can be coupled to a test for identity such that the results of the assay can be positively correlated to a subject's identity.

Rapid classification of biological components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thompson, Vicki S.; Barrett, Karen B.; Key, Diane E.

A method is disclosed for analyzing a biological sample by antibody profiling for identifying forensic samples or for detecting the presence of an analyte. In an illustrative embodiment of the invention, the analyte is a drug, such as marijuana, cocaine, methamphetamine, methyltestosterone, or mesterolone. The method involves attaching antigens to the surface of a solid support in a preselected pattern to form an array wherein the locations of the antigens are known; contacting the array with the biological sample such that a portion of antibodies in the sample reacts with and binds to antigens in the array, thereby forming immunemore » complexes; washing away antibodies that do form immune complexes; and detecting the immune complexes, thereby forming an antibody profile. Forensic samples are identified by comparing a sample from an unknown source with a sample from a known source. Further, an assay, such as a test for illegal drug use, can be coupled to a test for identity such that the results of the assay can be positively correlated to the subject's identity.« less

Antibody profiling sensitivity through increased reporter antibody layering

DOEpatents

Apel, William A.; Thompson, Vicki S.

2017-03-28

A method for analyzing a biological sample by antibody profiling for identifying forensic samples or for detecting the presence of an analyte. In an embodiment of the invention, the analyte is a drug, such as marijuana, Cocaine (crystalline tropane alkaloid), methamphetamine, methyltestosterone, or mesterolone. The method comprises attaching antigens to a surface of a solid support in a preselected pattern to form an array wherein locations of the antigens are known; contacting the array with the biological sample such that a portion of antibodies in the sample reacts with and binds to the antigens in the array to form immune complexes; washing away antibodies that do form immune complexes; and detecting the immune complexes, to form an antibody profile. Forensic samples are identified by comparing a sample from an unknown source with a sample from a known source. Further, an assay, such as a test for illegal drug use, can be coupled to a test for identity such that the results of the assay can be positively correlated to the subject's identity.

A rapid UPLC-MS/MS assay for eicosanoids in human plasma: Application to evaluate niacin responsivity.

PubMed

Miller, Tricia M; Poloyac, Samuel M; Anderson, Kacey B; Waddell, Brooke L; Messamore, Erik; Yao, Jeffrey K

2017-01-18

A rapid and sensitive method using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed to simultaneously quantify hydroxyeicosatetraenoic (HETE), dihydroxyeicosatrienoic (DiHETrE), epoxyeicosatrienoic acid (EET), and prostaglandin metabolites of arachidonic acid in human plasma. Sample preparation consisted of solid phase extraction with Oasis HLB (30mg) cartridges for all metabolites. Separation of HETEs, EETs, and DiHETrEs was achieved on an Acquity UPLC BEH C18, 1.7µm (100×2.1mm) reversed-phase column (Waters Corp, Millford, MA) with negative electrospray ionization mass spectrometric detection. A second injection of the same extracted sample allowed for separation and assessment of prostaglandin metabolites under optimized UPLC-MS/MS conditions. Additionally, the endogenous levels of these metabolites in five different matrices were determined in order to select the optimal matrix for assay development. Human serum albumin was shown to have the least amount of endogenous metabolites, a recovery efficiency of 79-100% and a matrix effect of 71 - 100%. Linear calibration curves ranging from 0.416 to 66.67ng/ml were validated. Inter-assay and intra-assay variance was less than 15% at most concentrations. This method was successfully applied to quantify metabolite levels in plasma samples of healthy control subjects receiving niacin administration to evaluate the association between niacin administration and eicosanoid plasma level response. Published by Elsevier Ltd.

A Liquid Phase Affinity Capture Assay Using Magnetic Beads to Study Protein-Protein Interaction: The Poliovirus-Nanobody Example

PubMed Central

Schotte, Lise; Rombaut, Bart; Thys, Bert

2012-01-01

In this article, a simple, quantitative, liquid phase affinity capture assay is presented. Provided that one protein can be tagged and another protein labeled, this method can be implemented for the investigation of protein-protein interactions. It is based on one hand on the recognition of the tagged protein by cobalt coated magnetic beads and on the other hand on the interaction between the tagged protein and a second specific protein that is labeled. First, the labeled and tagged proteins are mixed and incubated at room temperature. The magnetic beads, that recognize the tag, are added and the bound fraction of labeled protein is separated from the unbound fraction using magnets. The amount of labeled protein that is captured can be determined in an indirect way by measuring the signal of the labeled protein remained in the unbound fraction. The described liquid phase affinity assay is extremely useful when conformational conversion sensitive proteins are assayed. The development and application of the assay is demonstrated for the interaction between poliovirus and poliovirus recognizing nanobodies1. Since poliovirus is sensitive to conformational conversion2 when attached to a solid surface (unpublished results), the use of ELISA is limited and a liquid phase based system should therefore be preferred. An example of a liquid phase based system often used in polioresearch3,4 is the micro protein A-immunoprecipitation test5. Even though this test has proven its applicability, it requires an Fc-structure, which is absent in the nanobodies6,7. However, as another opportunity, these interesting and stable single-domain antibodies8 can be easily engineered with different tags. The widely used (His)6-tag shows affinity for bivalent ions such as nickel or cobalt, which can on their turn be easily coated on magnetic beads. We therefore developed this simple quantitative affinity capture assay based on cobalt coated magnetic beads. Poliovirus was labeled with 35S to enable unhindered interaction with the nanobodies and to make a quantitative detection feasible. The method is easy to perform and can be established with a low cost, which is further supported by the possibility of effectively regenerating the magnetic beads. PMID:22688388

HPLC analysis of 6-mercaptopurine and metabolites in extracellular body fluids.

PubMed

Rudy, J L; Argyle, J C; Winick, N; Van Dreal, P

1988-09-01

A convenient HPLC assay, which allows for the simultaneous measurement in extracellular fluids of 6-mercaptopurine and four of its metabolites, 6-thioguanine, 6-mercaptopurine riboside, 6-thioxanthine and 6-thiouric acid is described. Solid phase extraction allows for the clean isolation of analytes from plasma, urine or cerebrospinal fluid. The simultaneous determination of 6-mercaptopurine and some of its major metabolites in extracellular fluids may contribute to the monitoring of patient compliance, bioavailability, and individual variation in metabolism and absorption.

Fundamental tribological properties of ceramics

NASA Technical Reports Server (NTRS)

Buckley, D. H.; Miyoshi, K.

1985-01-01

When a ceramic is brought into contact with itself, another ceramic, or a metal, strong bond forces can develop between the materials. Adhesion between a ceramic and itself or another solid are discussed from a theoretical consideration of the nature of the surfaces and experimentally by relating bond forces to the interface resulting from solid state contact. Elastic, plastic, and fracture behavior of ceramics in solid-state contact are discussed as they relate to friction and wear. The contact load necessary to initiate fracture in ceramics is shown to be appreciably reduced with tangential motion. Both friction and wear of ceramics are anisotropic and relate to crystal structure as with metals. Both free energy of oxide formation and the d valence bond character of metals are related to the friction and wear characteristics for metals in contact with ceramics. Lubrication is found to increase the critical load necessary to initiate fracture of ceramics with sliding or rubbing contact.

Headspace sorptive solid phase microextraction (HS-SPME) combined with a spectrophotometry system: A simple glass devise for extraction and simultaneous determination of cyanide and thiocyanate in environmental and biological samples.

PubMed

Al-Saidi, H M; Al-Harbi, Sami A; Aljuhani, E H; El-Shahawi, M S

2016-10-01

A simple, low cost and efficient headspace sorptive solid phase microextraction (HS-SPME) method for determination of cyanide has been developed. The system comprises of a glass tube with two valves and a moveable glass slide fixed at its centre. It includes an acceptor phase polyurethane foam treated mercury (II) dithizonate [Hg(HDz)2-PUF] complex fixed inside by a septum cap in a cylindrical configuration (5.0cm length and 1.0cm diameter). The extraction is based upon the contact of the acceptor phase to the headspace and subsequently measuring the absorbance of the recovered mercury (II) dithizonate from PUFs sorbent. Unlike other HSSE, extraction and back - extractions was carried out in a closed system, thereby improving the analytical performance by preventing the analyte loss. Under the optimized conditions, a linear calibration plot in the range of 1.0-50.0µmolL(-1) was achieved with limits of detection (LOD) and quantification (LOQ) of 0.34, 1.2µmolL(-1) CN(-), respectively. Simultaneous analysis of cyanide and thiocyanate in saliva was also performed with satisfactory recoveries. Copyright © 2016. Published by Elsevier B.V.

Laser diode package with enhanced cooling

DOEpatents

Deri, Robert J [Pleasanton, CA; Kotovsky, Jack [Oakland, CA; Spadaccini, Christopher M [Oakland, CA

2011-09-13

A laser diode package assembly includes a reservoir filled with a fusible metal in close proximity to a laser diode. The fusible metal absorbs heat from the laser diode and undergoes a phase change from solid to liquid during the operation of the laser. The metal absorbs heat during the phase transition. Once the laser diode is turned off, the liquid metal cools off and resolidifies. The reservoir is designed such that that the liquid metal does not leave the reservoir even when in liquid state. The laser diode assembly further includes a lid with one or more fin structures that extend into the reservoir and are in contact with the metal in the reservoir.

Laser diode package with enhanced cooling

DOEpatents

Deri, Robert J [Pleasanton, CA; Kotovsky, Jack [Oakland, CA; Spadaccini, Christopher M [Oakland, CA

2012-06-12

A laser diode package assembly includes a reservoir filled with a fusible metal in close proximity to a laser diode. The fusible metal absorbs heat from the laser diode and undergoes a phase change from solid to liquid during the operation of the laser. The metal absorbs heat during the phase transition. Once the laser diode is turned off, the liquid metal cools off and resolidifies. The reservoir is designed such that that the liquid metal does not leave the reservoir even when in liquid state. The laser diode assembly further includes a lid with one or more fin structures that extend into the reservoir and are in contact with the metal in the reservoir.

Laser diode package with enhanced cooling

DOEpatents

Deri, Robert J; Kotovsky, Jack; Spadaccini, Christopher M

2012-06-26

A laser diode package assembly includes a reservoir filled with a fusible metal in close proximity to a laser diode. The fusible metal absorbs heat from the laser diode and undergoes a phase change from solid to liquid during the operation of the laser. The metal absorbs heat during the phase transition. Once the laser diode is turned off, the liquid metal cools off and resolidifies. The reservoir is designed such that that the liquid metal does not leave the reservoir even when in liquid state. The laser diode assembly further includes a lid with one or more fin structures that extend into the reservoir and are in contact with the metal in the reservoir.

Surfactant-Enhanced Benard Convection on an Evaporating Drop

NASA Astrophysics Data System (ADS)

Nguyen, Van X.; Stebe, Kathleen J.

2001-11-01

Surfactant effects on an evaporating drop are studied experimentally. Using a fluorescent probe, the distribution and surface phase of the surfactant is directly imaged throughout the evaporation process. From these experiments, we identify conditions in which surfactants promote surface tension-driven Benard instabilities in aqueous systems. The drops under study contain finely divided particles, which act as tracers in the flow, and form well-defined patterns after the drop evaporates. Two flow fields have been reported in this system. The first occurs because the contact line becomes pinned by solid particles at the contact line region. In order for the contact line to remain fixed, an outward flow toward the ring results, driving further accumulation at the contact ring. A ‘coffee ring’ of particles is left as residue after the drop evaporates[1]. The second flow is Benard convection, driven by surface tension gradients on the drop[2,3]. In our experiments, an insoluble monolayer of pentadecanoic acid is spread at the interface of a pendant drop. The surface tension is recorded, and the drop is deposited on a well-defined solid substrate. Fluorescent images of the surface phase of the surfactant are recorded as the drop evaporates. The surfactant monolayer assumes a variety of surface states as a function of the area per molecule at the interface: surface gaseous, surface liquid expanded, and surface liquid condensed phases[4]. Depending upon the surface state of the surfactant as the drop evaporates, transitions of residue patterns left by the particles occur, from the coffee ring pattern to Benard cells to irregular patterns, suggesting a strong resistance to outward flow are observed. The occurrence of Benard cells on a surfactant-rich interface occurs when the interface is in LE-LC coexistence. Prior research concerning surfactant effects on this instability predict that surfactants are strongly stabilizing[5]. The mechanisms for this change in behavior are discussed. References: [1]R. D. Deegan,, PRE 61,475 (2000). [2]M. Maillard et al., J. Phys. Chem. B 104, 11871 (2000). [3]H. Wang et al. Langmuir 15, 957 (2001). [4]B. G. Moore et al., J. Phys. Chem. 94, 4588 (1990). [5]J. C. Berg & A. Acrivos, Chem. Eng. Sci. 20,737 (1965).

Determination of the Contact Angle Based on the Casimir Effect

NASA Technical Reports Server (NTRS)

Mazuruk, Konstantin; Volz, Martin P.

2015-01-01

On a macroscopic scale, a nonreactive liquid partially covering a homogeneous solid surface will intersect the solid at an angle called the contact angle. For molten metals and semiconductors, the contact angle is materially dependent upon both the solid and liquid and typical values fall in the range 80-170 deg, depending on the crucible material. On a microscopic scale, there does not exist a precise and sharp contact angle but rather the liquid and solid surfaces merge smoothly and continuously. Consider the example of the so called detached Bridgman crystal growth process. In this technique, a small gap is formed between the growing crystal and the crucible. At the crystal/melt interface, a meniscus ring is formed. Its width can be in the range of a few micrometers, approaching a microscopic scale. It then becomes questionable to describe the shape of this meniscus by the contact angle. A more advanced treatment of the interface is needed and here we propose such a refined model. The interaction of the liquid surface with the solid can be calculated by considering two forces: a short-range repulsive force and a longer range (up to a few micrometers) Casimir or van der Waals force.

Color-gradient lattice Boltzmann model for simulating droplet motion with contact-angle hysteresis.

PubMed

Ba, Yan; Liu, Haihu; Sun, Jinju; Zheng, Rongye

2013-10-01

Lattice Boltzmann method (LBM) is an effective tool for simulating the contact-line motion due to the nature of its microscopic dynamics. In contact-line motion, contact-angle hysteresis is an inherent phenomenon, but it is neglected in most existing color-gradient based LBMs. In this paper, a color-gradient based multiphase LBM is developed to simulate the contact-line motion, particularly with the hysteresis of contact angle involved. In this model, the perturbation operator based on the continuum surface force concept is introduced to model the interfacial tension, and the recoloring operator proposed by Latva-Kokko and Rothman is used to produce phase segregation and resolve the lattice pinning problem. At the solid surface, the color-conserving wetting boundary condition [Hollis et al., IMA J. Appl. Math. 76, 726 (2011)] is applied to improve the accuracy of simulations and suppress spurious currents at the contact line. In particular, we present a numerical algorithm to allow for the effect of the contact-angle hysteresis, in which an iterative procedure is used to determine the dynamic contact angle. Numerical simulations are conducted to verify the developed model, including the droplet partial wetting process and droplet dynamical behavior in a simple shear flow. The obtained results are compared with theoretical solutions and experimental data, indicating that the model is able to predict the equilibrium droplet shape as well as the dynamic process of partial wetting and thus permits accurate prediction of contact-line motion with the consideration of contact-angle hysteresis.

Method of forming emitters for a back-contact solar cell

DOEpatents

Li, Bo; Cousins, Peter J.; Smith, David D.

2015-09-29

Methods of forming emitters for back-contact solar cells are described. In one embodiment, a method includes forming a first solid-state dopant source above a substrate. The first solid-state dopant source includes a plurality of regions separated by gaps. Regions of a second solid-state dopant source are formed above the substrate by printing.

Method of forming emitters for a back-contact solar cell

DOEpatents

Li, Bo; Cousins, Peter J; Smith, David D

2014-12-16

Methods of forming emitters for back-contact solar cells are described. In one embodiment, a method includes forming a first solid-state dopant source above a substrate. The first solid-state dopant source includes a plurality of regions separated by gaps. Regions of a second solid-state dopant source are formed above the substrate by printing.

Method or forming emitters for a back-contact solar cell

DOEpatents

Li, Bo; Cousins, Peter J.; Smith, David D.

2014-08-12

Methods of forming emitters for back-contact solar cells are described. In one embodiment, a method includes forming a first solid-state dopant source above a substrate. The first solid-state dopant source includes a plurality of regions separated by gaps. Regions of a second solid-state dopant source are formed above the substrate by printing.

Analysis of tricyclic antidepressant drugs in plasma by means of solid-phase microextraction-liquid chromatography-mass spectrometry.

PubMed

Alves, Claudete; Santos-Neto, Alvaro J; Fernandes, Christian; Rodrigues, José C; Lanças, Fernando M

2007-10-01

Solid-phase microextraction coupled to liquid chromatography and mass spectrometry (SPME-LC-MS) was used to analyze tricyclic antidepressant drugs desipramine, imipramine, nortriptyline, amitriptyline, and clomipramine (internal standard) in plasma samples. SPME was performed by direct extraction on a PDMS/DVB (60 microm) coated fiber, employing a stirring rate of 1200 rpm for 30 min, pH 11.0, and temperature of 30 degrees C. Drug desorption was carried out by exposing the fiber to the liquid chromatography mobile phase for 20 min, using a labmade SPME-LC interface at 50 degrees C. The main variables experimentally influencing LC-MS response were evaluated and mathematically modeled. A rational optimization with fewer experiments was achieved using a factorial design approach. The constructed empirical models were adjusted with 96-98% of explained deviation allowing an adequate data set comprehension. The chromatographic separation was realized using an RP-18 column (150 mm x 2.1 mm, 5 microm particles) and ammonium acetate buffer (0.01 mol/l, pH 5.50) : acetonitrile (50 : 50 v/v) as mobile phase. Low detection levels were achieved with electrospray interface (0.1 ng/ml). The developed method showed specificity, linearity, precision, and limit of quantification adequate to assay tricyclic antidepressant drugs in plasma.

Contact Angle of Drops Measured on Nontransparent Surfaces and Capillary Flow Visualized

NASA Technical Reports Server (NTRS)

Chao, David F.; Zhang, Nengli

2003-01-01

The spreading of a liquid on a solid surface is important for various practical processes, and contact-angle measurements provide an elegant method to characterize the interfacial properties of the liquid with the solid substrates. The complex physical processes occurring when a liquid contacts a solid play an important role in determining the performance of chemical processes and materials. Applications for these processes are in printing, coating, gluing, textile dyeing, and adhesives and in the pharmaceutical industry, biomedical research, adhesives, flat panel display manufacturing, surfactant chemistry, and thermal engineering.

A novel direct contact method for the assessment of the antimicrobial activity of dental cements.

PubMed

Costa, E M; Silva, S; Madureira, A R; Cardelle-Cobas, A; Tavaria, F K; Pintado, M M

2013-06-01

Dental cements are a crucial part of the odontological treatment, however, due to the hazardous nature and reduced biological efficiency of some of the used materials, newer and safer alternatives are needed, particularly so those possessing higher antimicrobial activity than their traditional counterparts. The evaluation of the antimicrobial properties of solid and semi-solid antimicrobials, such as dental cements and gels, is challenging, particularly due to the low sensitivity of the current methods. Thus, the main aim of this study was the evaluation of the antimicrobial activity of a novel chitosan containing dental cement while simultaneous assessing/validating a new, more efficient, method for the evaluation of the antimicrobial activity of solid and gel like materials. The results obtained showed that the proposed method exhibited a higher sensitivity than the standard 96 well microtiter assay and allowed the determination of bactericidal activity. Additionally, it is interesting to note that the chitosan containing cement, which presented higher antimicrobial activity than the traditional zinc oxide/eugenol mix, was capable of inducing a viable count reduction above 5 log of CFU for all of the studied microorganisms. Copyright © 2013 Elsevier B.V. All rights reserved.

Electrochemical performance and durability of carbon supported Pt catalyst in contact with aqueous and polymeric proton conductors.

PubMed

Andersen, Shuang Ma; Skou, Eivind

2014-10-08

Significant differences in catalyst performance and durability are often observed between the use of a liquid electrolyte (e.g., sulfuric acid), and a solid polymer electrolyte (e.g., Nafion). To understand this phenomenon, we studied the electrochemical behavior of a commercially available carbon supported platinum catalyst in four different electrode structures: catalyst powder (CP), catalyst ionomer electrode (CIE), half membrane electrode assembly (HMEA), and full membrane electrode assembly (FMEA) in both ex situ and in situ experiments under a simulated start/stop cycle. We found that the catalyst performance and stability are very much influenced by the presence of the Nafion ionomers. The proton conducting phase provided by the ionomer and the self-assembled electrode structure render the catalysts a higher utilization and better stability. This is probably due to an enhanced dispersion, an improved proton-catalyst interface, the restriction of catalyst particle aggregation, and the improved stability of the ionomer phase especially after the lamination. Therefore, an innovative electrode HMEA design for ex-situ catalyst characterization is proposed. The electrode structure is identical to the one used in a real fuel cell, where the protons transport takes place solely through solid state proton conducting phase.

Investigation of nutrient feeding strategies in a countercurrent mixed-acid multi-staged fermentation: development of segregated-nitrogen model.

PubMed

Smith, Aaron D; Holtzapple, Mark T

2010-12-01

The MixAlco process is a biorefinery based on the production of carboxylic acids via mixed-culture fermentation. Nitrogen is essential for microbial growth and metabolism, and may exist in soluble (e.g., ammonia) or insoluble forms (e.g., cells). Understanding the dynamics of nitrogen flow in a countercurrent fermentation is necessary to develop control strategies to maximize performance. To estimate nitrogen concentration profiles in a four-stage fermentation train, a mass balance-based segregated-nitrogen model was developed, which uses separate balances for solid- and liquid-phase nitrogen with nitrogen reaction flux between phases assumed to be zero. Comparison of predictions with measured nitrogen profiles from five trains, each with a different nutrient contacting pattern, shows the segregated-nitrogen model captures basic behavior and is a reasonable tool for estimating nitrogen profiles. The segregated-nitrogen model may be used to (1) estimate optimal nitrogen loading patterns, (2) develop a reaction-based model, (3) understand influence of model inputs (e.g., operating parameters, feedstock properties, nutrient loading pattern) on the steady-state nitrogen profile, and (4) determine the direction of the nitrogen reaction flux between liquid and solid phases. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Contact mechanics for poroelastic, fluid-filled media, with application to cartilage.

PubMed

Persson, B N J

2016-12-21

I study a simple contact mechanics model for a poroelastic, fluid-filled solid squeezed against a rigid, randomly rough substrate. I study how the fluid is squeezed out from the interface, and how the area of contact, and the average interfacial separation, change with time. I present numerical results relevant for a human cartilage. I show that for a fluid filled poroelastic solid the probability of cavitation (and the related wear as the cavities implode), and dynamical scraping (defined below and in Hutt and Persson, J. Chem. Phys. 144, 124903 (2016)), may be suppressed by fluid flow from the poroelastic solid into the (roughness induced) interfacial gap between the solids.

Contact mechanics for poroelastic, fluid-filled media, with application to cartilage

NASA Astrophysics Data System (ADS)

Persson, B. N. J.

2016-12-01

I study a simple contact mechanics model for a poroelastic, fluid-filled solid squeezed against a rigid, randomly rough substrate. I study how the fluid is squeezed out from the interface, and how the area of contact, and the average interfacial separation, change with time. I present numerical results relevant for a human cartilage. I show that for a fluid filled poroelastic solid the probability of cavitation (and the related wear as the cavities implode), and dynamical scraping (defined below and in Hutt and Persson, J. Chem. Phys. 144, 124903 (2016)), may be suppressed by fluid flow from the poroelastic solid into the (roughness induced) interfacial gap between the solids.

HPLC-electrospray mass spectrometric assay for the determination of (R,R)-fenoterol in rat plasma.

PubMed

Siluk, Danuta; Kim, Hee Seung; Cole, Tyler; Wainer, Irving W

2008-11-04

A fast and specific liquid chromatography-mass spectrometry method for the determination of (R,R)-fenoterol ((R,R)-Fen) in rat plasma has been developed and validated. (R,R)-Fen was extracted from 125 microl of plasma using solid phase extraction and analyzed on Atlantis HILIC Silica 3 microm column. The mobile phase was composed of acetonitrile:ammonium acetate (pH 4.1; 20mM) (85:15, v/v), at a flow rate of 0.2 ml/min. The lower limit of detection (LLOD) was 2 ng/ml . The procedure was validated and applied to the analysis of plasma samples from rats previously administered (R,R)-Fen in an intravenous bolus.

Coordination of tRNA transcription with export at nuclear pore complexes in budding yeast.

PubMed

Chen, Miao; Gartenberg, Marc R

2014-05-01

tRNAs are encoded by RNA polymerase III-transcribed genes that reside at seemingly random intervals along the chromosomes of budding yeast. Existing evidence suggests that the genes congregate together at the nucleolus and/or centromeres. In this study, we re-examined spatial and temporal aspects of tRNA gene (tDNA) expression. We show that tDNA transcription fluctuates during cell cycle progression. In M phase, when tRNA synthesis peaks, tDNAs localize at nuclear pore complexes (NPCs). Docking of a tDNA requires the DNA sequence of the contacted gene, nucleoporins Nup60 and Nup2, and cohesin. Characterization of mutants that block NPC localization revealed that docking is a consequence of elevated tDNA transcription. NPC-tDNA contact falters in the absence of the principal exportin of nascent tRNA, Los1, and genetic assays indicate that gating of tDNAs at NPCs favors cytoplasmic accumulation of functional tRNA. Collectively, the data suggest that tDNAs associate with NPCs to coordinate RNA polymerase III transcription with the nuclear export of pre-tRNA. The M-phase specificity of NPC contact reflects a regulatory mechanism that may have evolved, in part, to avoid collisions between DNA replication forks and transcribing RNA polymerase III machinery at NPCs.

Coordination of tRNA transcription with export at nuclear pore complexes in budding yeast

PubMed Central

Chen, Miao; Gartenberg, Marc R.

2014-01-01

tRNAs are encoded by RNA polymerase III-transcribed genes that reside at seemingly random intervals along the chromosomes of budding yeast. Existing evidence suggests that the genes congregate together at the nucleolus and/or centromeres. In this study, we re-examined spatial and temporal aspects of tRNA gene (tDNA) expression. We show that tDNA transcription fluctuates during cell cycle progression. In M phase, when tRNA synthesis peaks, tDNAs localize at nuclear pore complexes (NPCs). Docking of a tDNA requires the DNA sequence of the contacted gene, nucleoporins Nup60 and Nup2, and cohesin. Characterization of mutants that block NPC localization revealed that docking is a consequence of elevated tDNA transcription. NPC–tDNA contact falters in the absence of the principal exportin of nascent tRNA, Los1, and genetic assays indicate that gating of tDNAs at NPCs favors cytoplasmic accumulation of functional tRNA. Collectively, the data suggest that tDNAs associate with NPCs to coordinate RNA polymerase III transcription with the nuclear export of pre-tRNA. The M-phase specificity of NPC contact reflects a regulatory mechanism that may have evolved, in part, to avoid collisions between DNA replication forks and transcribing RNA polymerase III machinery at NPCs. PMID:24788517

LaNi0.6Co0 4O3-δ dip-coated on Fe-Cr mesh as a composite cathode contact material on intermediate solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Morán-Ruiz, Aroa; Vidal, Karmele; Larrañaga, Aitor; Laguna-Bercero, Miguel Angel; Porras-Vázquez, Jose Manuel; Slater, Peter Raymond; Arriortua, María Isabel

2014-12-01

The feasibility of using Crofer22APU mesh dip coated with LaNi0.6Co0.4O3-δ (LNC) ceramic paste as a uniform contact layer on a Crofer22APU channeled interconnect was studied. The control of LNC dip coating thickness on Fe-Cr mesh was carried out by rheological measurements of the suspension. SEM cross-section of formed composite contact material showed good adherence between ceramic and metallic components. The measured area specific resistance (ASR) value at 800 °C was 0.46 ± 0.01 mΩ cm2, indicating low contact resistance itself. The long term stability of metallic/ceramic composite was also studied. The contact resistance, when composite contact material was adhered to channeled Crofer22APU interconnect, was 5.40 ± 0.01 mΩ cm2, which is a suitable value for the performance of IT-SOFC stack. The stability of the system after treating at 800 °C for 1000 h was characterized using X-ray Micro-Diffraction (XRMD), Scanning Electron Microscope equipped with an Energy Dispersive X-ray analyzer (SEM-EDX) and X-ray Photoelectron Spectroscopy (XPS) techniques. The oxidation rate of the alloy and Fe3O4 phase formation were enhanced on the channels of the interconnect. Thus, the formation of CrO3 (g) and CrO2(OH)2 (g) species was accelerated on the composite surface under the channel. Through XRMD and XPS analysis the coexistence of two perovskite phases (initial LNC and Cr-perovskite) was observed.

Snakes on a plane: modeling flexible active nematics

NASA Astrophysics Data System (ADS)

Selinger, Robin

Active soft matter systems of self-propelled rod-shaped particles exhibit ordered phases and collective behavior that are remarkably different from their passive analogs. In nature, many self-propelled rod-shaped particles, such as gliding bacteria and kinesin-driven microtubules, are flexible and can bend. We model these ``living liquid crystals'' to explore their phase behavior, dynamics, and pattern formation. We model particles as short polymers via molecular dynamics with a Langevin thermostat and various types of activity, substrate, and environments. For self-propelled polar particles gliding on a solid substrate, we map out the phase diagram as a function of particle density and flexibility. We compare simulated defect structures to those observed in colonies of gliding myxobacteria; compare spooling behavior to that observed in microtubule gliding assays; and analyze emergence of nematic and polar order. Next we explore pattern formation of self-propelled polar particles under flexible encapsulation, and on substrates with non-uniform Gaussian curvature. Lastly, we impose an activity mechanism that mimics extensile shear, study flexible particles both on solid substrates and coupled to a lipid membrane, and discuss comparisons to relevant experiments. Work performed in collaboration with Michael Varga (Kent State) and Luca Giomi (Universiteit Leiden.) Work supported by NSF DMR-1409658.

Direct measurement of asperity contact growth in quartz at hydrothermal conditions

NASA Astrophysics Data System (ADS)

Beeler, N. M.; Hickman, S. H.

2008-12-01

Room-temperature friction and indentation experiments suggest fault strengthening during the interseismic period results from increases in asperity contact area due to solid-state deformation. However, field observations on exhumed fault zones indicate that solution-transport processes, pressure solution, crack healing and contact overgrowth, influence fault zone rheology near the base of the seismogenic zone. Contact overgrowths result from gradients in surface curvature, where material is dissolved from the pore walls, diffuses through the fluid and precipitates at the contact between two asperities, cementing the asperities together without convergence normal to the contact. To determine the mechanisms and kinetics of asperity cementation, we conducted laboratory experiments in which convex and flat lenses prepared from quartz single crystals were pressed together in an externally heated pressure vessel equipped with an optical observation port. Convergence between the two lenses and contact morphology were continuously monitored during these experiments using reflected-light interferometry through a long-working-distance microscope. Contact normal force is constant with an initial effective normal stress of 1.7 MPa. Four single-phase experiments were conducted at temperatures between 350 and 530C at 150 MPa water pressure, along with two controls: one single phase, dry at 425C and one bimaterial (qtz/sapphire) at 425C and 150 MPa water pressure. No contact growth or convergence was observed in either of the controls. For wet single-phase contacts, however, growth was initially rapid and then decreased with time following an inverse squared dependence of contact radius on aperture. No convergence was observed over the duration of these experiments, suggesting that neither significant pressure solution nor crystal plasticity occurred at these stresses and temperatures. The formation of fluid inclusions between the lenses indicate that the contact is not uniformly wetted. The contact is bounded by small regions of high aperture, reflecting local free-face dissolution as the source for the overgrowth, a definitive indication of diffusion-limited growth. Diffusion-limited growth is also consistent with the inverse squared aperture dependence. However, the apparent activation energy is ~125 kJ/mol, much higher than expected for silica diffusion in bulk water; at present we do not have a complete explanation for the high activation energy. When our lab-measured overgrowth rates are extrapolated to the 5 to 30 micron radius contacts inferred from near-field recordings of M-2 sized earthquakes in deep drill holes and mines (i.e., SAFOD and NELSAM), we predict rates of contact area increase that are orders of magnitude faster than seen in dry, room-temperature friction experiments. This suggests that natural strength recovery should be dominated by fluid-assisted processes at hypocentral conditions near the base of the seismogenic zone.

Leaching of copper and nickel in soil-water systems contaminated by bauxite residue (red mud) from Ajka, Hungary: the importance of soil organic matter.

PubMed

Lockwood, Cindy L; Stewart, Douglas I; Mortimer, Robert J G; Mayes, William M; Jarvis, Adam P; Gruiz, Katalin; Burke, Ian T

2015-07-01

Red mud is a highly alkaline (pH >12) waste product from bauxite ore processing. The red mud spill at Ajka, Hungary, in 2010 released 1 million m(3) of caustic red mud into the surrounding area with devastating results. Aerobic and anaerobic batch experiments and solid phase extraction techniques were used to assess the impact of red mud addition on the mobility of Cu and Ni in soils from near the Ajka spill site. Red mud addition increases aqueous dissolved organic carbon (DOC) concentrations due to soil alkalisation, and this led to increased mobility of Cu and Ni complexed to organic matter. With Ajka soils, more Cu was mobilised by contact with red mud than Ni, despite a higher overall Ni concentration in the solid phase. This is most probably because Cu has a higher affinity to form complexes with organic matter than Ni. In aerobic experiments, contact with the atmosphere reduced soil pH via carbonation reactions, and this reduced organic matter dissolution and thereby lowered Cu/Ni mobility. These data show that the mixing of red mud into organic rich soils is an area of concern, as there is a potential to mobilise Cu and Ni as organically bound complexes, via soil alkalisation. This could be especially problematic in locations where anaerobic conditions can prevail, such as wetland areas contaminated by the spill.

A three-phase in-vitro system for studying Pseudomonas aeruginosa adhesion and biofilm formation upon hydrogel contact lenses

PubMed Central

2010-01-01

Background Pseudomonas aeruginosa is commonly associated with contact lens (CL) -related eye infections, for which bacterial adhesion and biofilm formation upon hydrogel CLs is a specific risk factor. Whilst P. aeruginosa has been widely used as a model organism for initial biofilm formation on CLs, in-vitro models that closely reproduce in-vivo conditions have rarely been presented. Results In the current investigation, a novel in-vitro biofilm model for studying the adherence of P. aeruginosa to hydrogel CLs was established. Nutritional and interfacial conditions similar to those in the eye of a CL wearer were created through the involvement of a solid:liquid and a solid:air interface, shear forces and a complex artificial tear fluid. Bioburdens varied depending on the CL material and biofilm maturation occurred after 72 h incubation. Whilst a range of biofilm morphologies were visualised including dispersed and adherent bacterial cells, aggregates and colonies embedded in extracellular polymer substances (EPS), EPS fibres, mushroom-like formations, and crystalline structures, a compact and heterogeneous biofilm morphology predominated on all CL materials. Conclusions In order to better understand the process of biofilm formation on CLs and to test the efficacy of CL care solutions, representative in-vitro biofilm models are required. Here, we present a three-phase biofilm model that simulates the environment in the eye of a CL wearer and thus generates biofilms which resemble those commonly observed in-situ. PMID:21062489

Influence of Amphibian Antimicrobial Peptides and Short Lipopeptides on Bacterial Biofilms Formed on Contact Lenses

PubMed Central

Maciejewska, Magdalena; Bauer, Marta; Neubauer, Damian; Kamysz, Wojciech; Dawgul, Malgorzata

2016-01-01

The widespread use of contact lenses is associated with several complications, including ocular biofilm-related infections. They are very difficult to manage with standard antimicrobial therapies, because bacterial growth in a biofilm is associated with an increased antibiotic resistance. The principal aim of this study was to evaluate the efficacy of antimicrobial peptides (AMPs) in eradication of bacterial biofilms formed on commercially available contact lenses. AMPs were synthesized according to Fmoc/tBu chemistry using the solid-phase method. Minimum inhibitory concentration (MIC) and minimum biofilm eradication concentration (MBEC) of the compounds were determined. Anti-biofilm activity of the antimicrobial peptides determined at different temperatures (25 °C and 37 °C) were compared with the effectiveness of commercially available contact lens solutions. All of the tested compounds exhibited stronger anti-biofilm properties as compared to those of the tested lens solutions. The strongest activity of AMPs was noticed against Gram-positive strains at a temperature of 25 °C. Conclusions: The results of our experiments encourage us toward further studies on AMPs and their potential application in the prophylaxis of contact lens-related eye infections. PMID:28773992

Measurement of contact-line dissipation in a nanometer-thin soap film

NASA Astrophysics Data System (ADS)

Guo, Shuo; Lee, Chun Huen; Sheng, Ping; Tong, Penger

2015-01-01

We report a direct measurement of the friction coefficient ξc of two fluctuating contact lines formed on a fiber surface when a long glass fiber intersects the two water-air interfaces of a thin soap film. The glass fiber of diameter d in the range of 0.4-4 μ m and length 100-300 μ m is glued onto the front end of a rectangular cantilever used for atomic force microscopy. As a sensitive mechanical resonator, the hanging fiber probe can accurately measure a minute change of its viscous damping caused by the soap film. By measuring the broadening of the resonant peak of the hanging fiber probe with varying viscosity η of the soap film and different surface treatments of the glass fiber, we confirm that the contact line dissipation obeys a universal scaling law, ξc=α π d η , where the coefficient α =1.1 ±0.3 is insensitive to the change of liquid-solid contact angle. The experimental result is in good agreement with the numerical result based on the phase field model under the generalized Navier boundary conditions.

Measurement of contact-line dissipation in a nanometer-thin soap film.

PubMed

Guo, Shuo; Lee, Chun Huen; Sheng, Ping; Tong, Penger

2015-01-01

We report a direct measurement of the friction coefficient ξ(c) of two fluctuating contact lines formed on a fiber surface when a long glass fiber intersects the two water-air interfaces of a thin soap film. The glass fiber of diameter d in the range of 0.4-4 μm and length 100-300 μm is glued onto the front end of a rectangular cantilever used for atomic force microscopy. As a sensitive mechanical resonator, the hanging fiber probe can accurately measure a minute change of its viscous damping caused by the soap film. By measuring the broadening of the resonant peak of the hanging fiber probe with varying viscosity η of the soap film and different surface treatments of the glass fiber, we confirm that the contact line dissipation obeys a universal scaling law, ξ(c)=απdη, where the coefficient α=1.1±0.3 is insensitive to the change of liquid-solid contact angle. The experimental result is in good agreement with the numerical result based on the phase field model under the generalized Navier boundary conditions.

Diffusion of Antimicrobials Across Silicone Hydrogel Contact Lenses

PubMed Central

Zambelli, Alison M.; Brothers, Kimberly M.; Hunt, Kristin M.; Romanowski, Eric G.; Nau, Amy C.; Dhaliwal, Deepinder K.; Shanks, Robert M. Q.

2014-01-01

Objectives To measure the diffusion of topical preparations of moxifloxacin, amphotericin B (AmB), and polyhexamethylene biguanide (PHMB) through silicone hydrogel (SH) contact lenses in vitro. Methods Using an in vitro model, the diffusion of three antimicrobials through SH contact lenses was measured. Diffused compounds were measured using a spectrophotometer at set time points over a period of four hours. The amount of each diffused antimicrobial was determined by comparing the experimental value to a standard curve. A biological assay was performed to validate the contact lens diffusion assay by testing antimicrobial activity of diffused material against lawns of susceptible bacteria (Staphylococcus epidermidis) and yeast (Saccharomyces cerevisiae). Experiments were repeated at least two times with a total of at least 4 independent replicates. Results Our data show detectable moxifloxacin and PHMB diffusion through SH contact lenses at 30 minutes, while amphotericin B diffusion remained below the limit of detection within the 4 hour experimental period. In the biological assay, diffused moxifloxacin demonstrated microbial killing starting at 20 minutes on bacterial lawns, whereas PHMB and amphotericin B failed to demonstrate killing on microbial lawns over the course of the 60 minute experiment. Conclusions In vitro diffusion assays demonstrate limited penetration of certain anti-infective agents through silicone hydrogel contact lenses. Further studies regarding the clinical benefit of using these agents along with bandage contact lens use for corneal pathology are warranted. PMID:25806673

An optoelectronic framework enabled by low-dimensional phase-change films.

PubMed

Hosseini, Peiman; Wright, C David; Bhaskaran, Harish

2014-07-10

The development of materials whose refractive index can be optically transformed as desired, such as chalcogenide-based phase-change materials, has revolutionized the media and data storage industries by providing inexpensive, high-speed, portable and reliable platforms able to store vast quantities of data. Phase-change materials switch between two solid states--amorphous and crystalline--in response to a stimulus, such as heat, with an associated change in the physical properties of the material, including optical absorption, electrical conductance and Young's modulus. The initial applications of these materials (particularly the germanium antimony tellurium alloy Ge2Sb2Te5) exploited the reversible change in their optical properties in rewritable optical data storage technologies. More recently, the change in their electrical conductivity has also been extensively studied in the development of non-volatile phase-change memories. Here we show that by combining the optical and electronic property modulation of such materials, display and data visualization applications that go beyond data storage can be created. Using extremely thin phase-change materials and transparent conductors, we demonstrate electrically induced stable colour changes in both reflective and semi-transparent modes. Further, we show how a pixelated approach can be used in displays on both rigid and flexible films. This optoelectronic framework using low-dimensional phase-change materials has many likely applications, such as ultrafast, entirely solid-state displays with nanometre-scale pixels, semi-transparent 'smart' glasses, 'smart' contact lenses and artificial retina devices.

Procedure for pressure contact on high-power semiconductor devices free of thermal fatigue

NASA Technical Reports Server (NTRS)

Knobloch, J.

1979-01-01

To eliminate thermal fatigue, a procedure for manufacturing semiconductor power devices with pure pressure contact without solid binding was developed. Pressure contact without the use of a solid binding to avoid a limitation of the maximum surface in the contact was examined. A silicon wafer covered with a relatively thick metal layer is imbedded with the aid of a soft silver foil between two identically sized hard contact discs (molybdenum or tungsten) which are rotationally symmetrical. The advantages of this concept are shown for large diameters. The pressure contact was tested successfully in many devices in a large variety of applications.

Total and Viable Legionella pneumophila Cells in Hot and Natural Waters as Measured by Immunofluorescence-Based Assays and Solid-Phase Cytometry ▿†

PubMed Central

Parthuisot, N.; Binet, M.; Touron-Bodilis, A.; Pougnard, C.; Lebaron, P.; Baudart, J.

2011-01-01

A new method was developed for the rapid and sensitive detection of viable Legionella pneumophila. The method combines specific immunofluorescence (IF) staining using monoclonal antibodies with a bacterial viability marker (ChemChrome V6 cellular esterase activity marker) by means of solid-phase cytometry (SPC). IF methods were applied to the detection and enumeration of both the total and viable L. pneumophila cells in water samples. The sensitivity of the IF methods coupled to SPC was 34 cells liter−1, and the reproducibility was good, with the coefficient of variation generally falling below 30%. IF methods were applied to the enumeration of total and viable L. pneumophila cells in 46 domestic hot water samples as well as in cooling tower water and natural water samples, such as thermal spring water and freshwater samples. Comparison with standard plate counts showed that (i) the total direct counts were always higher than the plate counts and (ii) the viable counts were higher than or close to the plate counts. With domestic hot waters, when the IF assay was combined with the viability test, SPC detected up to 3.4 × 103 viable but nonculturable L. pneumophila cells per liter. These direct IF methods could be a powerful tool for high-frequency monitoring of domestic hot waters or for investigating the occurrence of viable L. pneumophila in both man-made water systems and environmental water samples. PMID:21742913

Analysis of Benzo[a]pyrene in Vegetable Oils Using Molecularly Imprinted Solid Phase Extraction (MISPE) Coupled with Enzyme-Linked Immunosorbent Assay (ELISA)

PubMed Central

Pschenitza, Michael; Hackenberg, Rudolf; Niessner, Reinhard; Knopp, Dietmar

2014-01-01

This paper describes the development of a molecularly imprinted polymer-based solid phase extraction (MISPE) method coupled with enzyme-linked immunosorbent assay (ELISA) for determination of the PAH benzo[a]pyrene (B[a]P) in vegetable oils. Different molecularly imprinted polymers (MIPs) were prepared using non-covalent 4-vinylpyridine/divinylbenzene co-polymerization at different ratios and dichloromethane as porogen. Imprinting was done with a template mixture of phenanthrene and pyrene yielding a broad-specific polymer for PAHs with a maximum binding capacity (Q) of ∼32 μg B[a]P per 50 mg of polymer. The vegetable oil/n-hexane mixture (1:1, (v/v)) was pre-extracted with acetonitrile, the solvent evaporated, the residue reconstituted in n-hexane and subjected to MISPE. The successive washing with n-hexane and isopropanol revealed most suitable to remove lipid matrix constituents. After elution of bound PAHs from MISPE column with dichloromethane, the solvent was evaporated, the residue reconstituted with dimethyl sulfoxide and diluted 100-fold with methanol/water (10:90, (v/v)) for analysis of B[a]P equivalents with an ELISA. The B[a]P recovery rates in spiked vegetable oil samples of different fatty acid composition were determined between 63% and 114%. The presence of multiple PAHs in the oil sample, because of MIP selectivity and cross-reactivity of the ELISA, could yield overestimated B[a]P values. PMID:24887045

Direct measurement of asperity contact growth in quartz at hydrothermal conditions

USGS Publications Warehouse

Beeler, Nicholas M.; Hickman, Stephen H.

2015-01-01

Earthquake recurrence requires interseismic fault restrengthening which results from solid state deformation in room-temperature friction and indentation experiments. In contrast exhumed fault zones show solution-transport processes such as pressure solution and contact overgrowths influence fault zone properties . In the absence of fluid flow, overgrowths are driven by gradients in surface curvature where material is dissolved, diffuses, and precipitates at the contact without convergence normal to the contact. To determine the rate of overgrowth for quartz, we conducted single contact experiments in an externally heated pressure vessel. Convergence was continuously monitored using reflected-light interferometry through a long-working-distance microscope. Contact normal force was constant with an initial effective normal stress of 1.7 MPa, temperature was between 350 and 530{degree sign}C, and water pressure was constant at 150 MPa. Two control experiments were conducted: one dry at 425{degree sign}C and one bi-material (sapphire) at 425{degree sign}C and 150 MPa water pressure. No contact growth or convergence was observed in the controls. For wet single-phase contacts, growth was initially rapid and then decreased with time. No convergence was observed. Fluid inclusions indicate that the contact is not uniformly wetted. The contact is bounded by small regions of high aperture, reflecting local free-face dissolution as the source for the overgrowth. The apparent activation energy is ~125 kJ/mol. Extrapolation predicts rates of contact area increase orders of magnitude faster than in dry, room-temperature and hydrothermal friction experiments, suggesting that natural strength recovery near the base of the seismogenic zone could be dominated by contact overgrowth.

System and technique for characterizing fluids using ultrasonic diffraction grating spectroscopy

DOEpatents

Greenwood, Margaret S [Richland, WA

2008-07-08

A system for determining property of multiphase fluids based on ultrasonic diffraction grating spectroscopy includes a diffraction grating on a solid in contact with the fluid. An interrogation device delivers ultrasound through the solid and a captures a reflection spectrum from the diffraction grating. The reflection spectrum exhibits peaks whose relative size depends on the properties of the various phases of the multiphase fluid. For example, for particles in a liquid, the peaks exhibit dependence on the particle size and the particle volume fraction. Where the exact relationship is know know a priori, data from different peaks of the same reflection spectrum or data from the peaks of different spectra obtained from different diffraction gratings can be used to resolve the size and volume fraction.

On optimizing the blocking step of indirect enzyme-linked immunosorbent assay for Epstein-Barr virus serology.

PubMed

Lim, Chun Shen; Krishnan, Gopala; Sam, Choon Kook; Ng, Ching Ching

2013-01-16

Because blocking agent occupies most binding surface of a solid phase, its ability to prevent nonspecific binding determines the signal-to-noise ratio (SNR) and reliability of an enzyme-linked immunosorbent assay (ELISA). We demonstrate a stepwise approach to seek a compatible blocking buffer for indirect ELISA, via a case-control study (n=176) of Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC). Regardless of case-control status, we found that synthetic polymer blocking agents, mainly Ficoll and poly(vinyl alcohol) (PVA) were able to provide homogeneous backgrounds among samples, as opposed to commonly used blocking agents, notably nonfat dry milk (NFDM). The SNRs for NPC samples that correspond to blocking using PVA were approximately 3-fold, on average, higher than those blocking using NFDM. Both intra- and inter-assay precisions of PVA-based assays were <14%. A blocking agent of choice should have tolerable sample backgrounds from both cases and controls to ensure the reliability of an immunoassay. Copyright © 2012 Elsevier B.V. All rights reserved.

Grafted functional groups on expanded tetrafluoroethylene (ePTFE) support for fuel cell and water transport membranes

DOEpatents

Fuller, Timothy J.; Jiang, Ruichun

2017-01-24

A method for forming a modified solid polymer includes a step of contacting a solid fluorinated polymer with a sodium sodium-naphthalenide solution to form a treated fluorinated solid polymer. The treated fluorinated solid polymer is contacted with carbon dioxide, sulfur dioxide, or sulfur trioxide to form a solid grafted fluorinated polymer. Characteristically, the grafted fluorinated polymer includes appended CO.sub.2H or SO.sub.2H or SO.sub.3H groups. The solid grafted fluorinated polymer is advantageously incorporated into a fuel cell as part of the ion-conducting membrane or a water transport membrane in a humidifier.

Solid-phase receptor-based assay for the detection of cyclic imines by chemiluminescence, fluorescence, or colorimetry.

PubMed

Rodríguez, Laura P; Vilariño, Natalia; Molgó, Jordi; Aráoz, Rómulo; Antelo, Alvaro; Vieytes, Mercedes R; Botana, Luis M

2011-08-01

The spirolides and gymnodimines are marine phycotoxins included in the group of cyclic imines. The toxicity of these compounds to humans is still unknown, although their toxicity by intraperitoneal injection in rodents is very high. A receptor-based method was developed using the competition of the 13-desmethyl spirolide C with biotin-labeled α-bungarotoxin for binding to nicotinic acetylcholine receptors and the immobilization of the α-bungarotoxin-receptor complex on streptavidin-coated surfaces. The quantification of the immobilized receptor can be achieved using a specific antibody. Finally, after the addition of a secondary antibody labeled with horseradish peroxidase, three alternative substrates of this enzyme generate a chemiluminescent, fluorescent, or colorimetric signal. The assay performs well in shellfish extracts and the detection range is 5-150 nM of 13-desmethyl spirolide C in shellfish extracts, which is at least 5 times more sensitive than the existing fluorescence polarization assay. This assay can also detect gymnodimine, although with 10 times lower sensitivity than the spirolide. The detection of cyclic imines with microplate assays would be useful for screening purposes in order to reduce the number of samples to be processed by bioassays or analytical methods.

High-resolution α-amylase assay combined with high-performance liquid chromatography-solid-phase extraction-nuclear magnetic resonance spectroscopy for expedited identification of α-amylase inhibitors: proof of concept and α-amylase inhibitor in cinnamon.

PubMed

Okutan, Leyla; Kongstad, Kenneth T; Jäger, Anna K; Staerk, Dan

2014-11-26

Type 2 diabetes affects millions of people worldwide, and new improved drugs or functional foods containing selective α-amylase inhibitors are needed for improved management of blood glucose. In this article the development of a microplate-based high-resolution α-amylase inhibition assay with direct photometric measurement of α-amylase activity is described. The inhibition assay is based on porcine pancreatic α-amylase with 2-chloro-4-nitrophenyl-α-D-maltotriose as substrate, which this gives a stable, sensitive, and cheap inhibition assay as requested for high-resolution purposes. In combination with HPLC-HRMS-SPE-NMR, this provides an analytical platform that allows simultaneous chemical and biological profiling of α-amylase inhibitors in plant extracts. Proof-of-concept with an artificial mixture of six compounds-of which three are known α-amylase inhibitors-showed that the high-resolution α-amylase inhibition profiles allowed detection of sub-microgram amounts of the α-amylase inhibitors. Furthermore, the high-resolution α-amylase inhibition assay/HPLC-HRMS-SPE-NMR platform allowed identification of cinnamaldehyde as the α-amylase inhibitor in cinnamon (Cinnamomum verum Presl.).

EFFECTIVE POROSITY IMPLIES EFFECTIVE BULK DENSITY IN SORBING SOLUTE TRANSPORT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flach, G.

2012-02-27

The concept of an effective porosity is widely used in solute transport modeling to account for the presence of a fraction of the medium that effectively does not influence solute migration, apart from taking up space. This non-participating volume or ineffective porosity plays the same role as the gas phase in single-phase liquid unsaturated transport: it increases pore velocity, which is useful towards reproducing observed solute travel times. The prevalent use of the effective porosity concept is reflected by its prominent inclusion in popular texts, e.g., de Marsily (1986), Fetter (1988, 1993) and Zheng and Bennett (2002). The purpose ofmore » this commentary is to point out that proper application of the concept for sorbing solutes requires more than simply reducing porosity while leaving other material properties unchanged. More specifically, effective porosity implies the corresponding need for an effective bulk density in a conventional single-porosity model. The reason is that the designated non-participating volume is composed of both solid and fluid phases, both of which must be neglected for consistency. Said another way, if solute does not enter the ineffective porosity then it also cannot contact the adjoining solid. Conceptually neglecting the fluid portion of the non-participating volume leads to a lower (effective) porosity. Likewise, discarding the solid portion of the non-participating volume inherently leads to a lower or effective bulk density. In the author's experience, practitioners virtually never adjust bulk density when adopting the effective porosity approach.« less

Rapid Automated Sample Preparation for Biological Assays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shusteff, M

Our technology utilizes acoustic, thermal, and electric fields to separate out contaminants such as debris or pollen from environmental samples, lyse open cells, and extract the DNA from the lysate. The objective of the project is to optimize the system described for a forensic sample, and demonstrate its performance for integration with downstream assay platforms (e.g. MIT-LL's ANDE). We intend to increase the quantity of DNA recovered from the sample beyond the current {approx}80% achieved using solid phase extraction methods. Task 1: Develop and test an acoustic filter for cell extraction. Task 2: Develop and test lysis chip. Task 3:more » Develop and test DNA extraction chip. All chips have been fabricated based on the designs laid out in last month's report.« less

Electrospun poly-l-lactide scaffold for the controlled and targeted delivery of a synthetically obtained Diclofenac prodrug to treat actinic keratosis.

PubMed

Piccirillo, Germano; Bochicchio, Brigida; Pepe, Antonietta; Schenke-Layland, Katja; Hinderer, Svenja

2017-04-01

Actinic Keratosis' (AKs) are small skin lesions that are related to a prolonged sun-damage, which can develop into invasive squamous cell carcinoma (SCC) when left untreated. Effective, specific and well tolerable therapies to cure AKs are still of great interest. Diclofenac (DCF) is the current gold standard for the local treatment of AKs in terms of costs, effectiveness, side effects and tolerability. In this work, an electrospun polylactic acid (PLA) scaffold loaded with a synthetic DCF prodrug was developed and characterized. Specifically, the prodrug was successfully synthetized by binding DCF to a glycine residue via solid phase peptide synthesis (SPPS) and then incorporated in an electrospun PLA scaffold. The drug encapsulation was verified using multiphoton microscopy (MPM) and its scaffold release was spectrophotometrically monitored and confirmed with MPM. The scaffold was further characterized with scanning electron microscopy (SEM), tensile testing and contact angle measurements. Its biocompatibility was verified by performing a cell proliferation assay and compared to PLA scaffolds containing the same amount of DCF sodium salt (DCFONa). Finally, the effect of the electrospun scaffolds on human dermal fibroblasts (HDFs) morphology and metabolism was investigated by combining MPM with fluorescence lifetime imaging microscopy (FLIM). The obtained results suggest that the obtained scaffold could be suitable for the controlled and targeted delivery of the synthesized prodrug for the treatment of AKs. Electrospun scaffolds are of growing interest as materials for a controlled drug delivery. In this work, an electrospun polylactic acid scaffold containing a synthetically obtained Diclofenac prodrug is proposed as a novel substrate for the topical treatment of actinic keratosis. A controlled drug delivery targeted to the area of interest could enhance the efficacy of the therapy and favor the healing process. The prodrug was synthesized via solid phase, employing a clean and versatile approach to obtain Diclofenac derivatives. Here, we used multiphoton microscopy to image drug encapsulation within the fibrous scaffold and fluorescence lifetime imaging microscopy to investigate Diclofenac effects and potential mechanisms of action. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Cytotoxicity Evaluation and Magnetic Characteristics of Mechano-thermally Synthesized CuNi Nanoparticles for Hyperthermia

NASA Astrophysics Data System (ADS)

Amrollahi, P.; Ataie, A.; Nozari, A.; Seyedjafari, E.; Shafiee, A.

2015-03-01

CuNi alloys are very well known, both in academia and industry, based on their wide range of applications. In the present investigation, the previously synthesized Cu0.5Ni0.5 nanoparticles (NPs) by mechano-thermal method were studied more extensively. Phase composition and morphology of the samples were studied by employing x-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) techniques. The Curie temperature ( T c) was determined by differential scanning calorimetry (DSC). In vitro cytotoxicity was studied through methyl-thiazolyl-tetrazolium (MTT) assay. XRD and FESEM results indicated the formation of single-phase Cu0.5Ni0.5. TEM micrographs showed that the mean particle size of powders is 20 nm. DSC results revealed that T c of mechano-thermally synthesized Cu0.5Ni0.5 is 44 °C. The MTT assay results confirmed the viability and proliferation of human bone marrow stem cells in contact with Cu0.5Ni0.5 NPs. In summary, the fabricated particles were demonstrated to have potential in low concentrations for cancer treatment applications.

CHARACTERIZATION OF TANK 16H ANNULUS SAMPLES PART II: LEACHING RESULTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hay, M.; Reboul, S.

2012-06-19

The closure of Tank 16H will require removal of material from the annulus of the tank. Samples from Tank 16H annulus were characterized and tested to provide information to evaluate various alternatives for removing the annulus waste. The analysis found all four annulus samples to be composed mainly of Si, Na, and Al and lesser amounts of other elements. The XRD data indicate quartz (SiO{sub 2}) and sodium aluminum nitrate silicate hydrate (Na{sub 8}(Al{sub 6}Si{sub 6}O{sub 24})(NO{sub 3}){sub 2}.4H{sub 2}O) as the predominant crystalline mineral phases in the samples. The XRD data also indicate the presence of crystalline sodium nitratemore » (NaNO{sub 3}), sodium nitrite (NaNO{sub 2}), gibbsite (Al(OH){sub 3}), hydrated sodium bicarbonate (Na{sub 3}H(CO{sub 3}){sub 2}.2H{sub 2}O), and muscovite (KAl{sub 2}(AlSi{sub 3}O{sub 10})(OH){sub 2}). Based on the weight of solids remaining at the end of the test, the water leaching test results indicate 20-35% of the solids dissolved after three contacts with an approximately 3:1 volume of water at 45 C. The chemical analysis of the leachates and the XRD results of the remaining solids indicate sodium salts of nitrate, nitrite, sulfate, and possibly carbonate/bicarbonate make up the majority of the dissolved material. The majority of these salts were dissolved in the first water contact and simply diluted with each subsequent water contact. The water leaching removed large amounts of the uranium in two of the samples and approximately 1/3 of the {sup 99}Tc from all four samples. Most of the other radionuclides analyzed showed low solubility in the water leaching test. The oxalic acid leaching test result indicate approximately 34-47% of the solids in the four annulus samples will dissolve after three contacts with an approximately 3:1 volume of acid to solids at 45 C. The same sodium salts found in the water leaching test comprise the majority of dissolved material in the oxalic acid leaching test. However, the oxalic acid was somewhat more effective in dissolving radionuclides than the water leach. In contrast to the water leaching results, most constituents continued to dissolve during subsequent cycles of oxalic acid leaching. The somewhat higher dissolution found in the oxalic acid leaching test versus the water leaching test might be offset by the tendency of the oxalic acid solutions to take on a gel-like consistency. The filtered solids left behind after three oxalic acid contacts were sticky and formed large clumps after drying. These two observations could indicate potential processing difficulties with solutions and solids from oxalic acid leaching. The gel formation might be avoided by using larger volumes of the acid. Further testing would be recommended before using oxalic acid to dissolve the Tank 16H annulus waste to ensure no processing difficulties are encountered in the full scale process.« less

Research on acting mechanism and behavior of a gas bubble in the air dense medium fluidized bed

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tao, X.; Chen, Q.; Yang, Y.

1996-12-31

Coal dry beneficiation with air-dense medium fluidized bed has now been established as a high efficiency dry separation technology, it is the application of fluidization technology to the coal preparation field. The tiny particle media forms an uniform and stable fluidized bed with a density acted by airflow, which is used to separate 80{micro}m to {approximately}6mm size coal. This technology has achieved satisfied industrialization results, and attracted the expert`s attention in the field. In fluidized bed, the interaction between gas and solid was mainly decided by the existence state of heavy media particles mass (position and distance) relative velocity ofmore » gas-solid two phase, as well turbulent action. A change of vertical gas-solid fluidizing state essentially is the one of a energy transforming process. For a coal separating process with air-dense medium fluidized bed, the gas bubble, producing a turbulent and stirring action in the bed, leads to two effects. It can promote a uniform distribution of heavy media particles, and a uniform and stability of a bed density. Otherwise it will decrease effective contacts between gas-solids two phases, producing a bigger gas bubble. Therefore controlling a gas bubble size in bed should be optimized. This paper analyzes mutual movement between gas-solid, and studies the gas bubble behavior in the bed. A mechanic mode and a separating process of coal in the bed is discussed. It aims to research the coal separating mechanism with air-dense fluidized bed.« less

Design and development of molecularly imprinted polymers for the selective extraction of deltamethrin in olive oil: An integrated computational-assisted approach.

PubMed

Martins, Nuno; Carreiro, Elisabete P; Locati, Abel; Ramalho, João P Prates; Cabrita, Maria João; Burke, Anthony J; Garcia, Raquel

2015-08-28

This work firstly addresses the design and development of molecularly imprinted systems selective for deltamethrin aiming to provide a suitable sorbent for solid phase (SPE) extraction that will be further used for the implementation of an analytical methodology for the trace analysis of the target pesticide in spiked olive oil samples. To achieve this goal, a preliminary evaluation of the molecular recognition and selectivity of the molecularly imprinted polymers has been performed. In order to investigate the complexity of the mechanistic basis for template selective recognition in these polymeric matrices, the use of a quantum chemical approach has been attempted providing new insights about the mechanisms underlying template recognition, and in particular the crucial role of the crosslinker agent and the solvent used. Thus, DFT calculations corroborate the results obtained by experimental molecular recognition assays enabling one to select the most suitable imprinting system for MISPE extraction technique which encompasses acrylamide as functional monomer and ethylene glycol dimethacrylate as crosslinker. Furthermore, an analytical methodology comprising a sample preparation step based on solid phase extraction has been implemented using this "tailor made" imprinting system as sorbent, for the selective isolation/pre-concentration of deltamethrin from olive oil samples. Molecularly imprinted solid phase extraction (MISPE) methodology was successfully applied for the clean-up of spiked olive oil samples, with recovery rates up to 94%. Copyright © 2015 Elsevier B.V. All rights reserved.

Non-animal sensitization testing: state-of-the-art.

PubMed

Vandebriel, Rob J; van Loveren, Henk

2010-05-01

Predictive tests to identify the sensitizing properties of chemicals are carried out using animals. In the European Union timelines for phasing out many standard animal tests were established for cosmetics. Following this policy, the new European Chemicals Legislation (REACH) favors alternative methods, if validated and appropriate. In this review the authors aim to provide a state-of-the art overview of alternative methods (in silico, in chemico, and in vitro) to identify contact and respiratory sensitizing capacity and in some occasions give a measure of potency. The past few years have seen major advances in QSAR (quantitative structure-activity relationship) models where especially mechanism-based models have great potential, peptide reactivity assays where multiple parameters can be measured simultaneously, providing a more complete reactivity profile, and cell-based assays. Several cell-based assays are in development, not only using different cell types, but also several specifically developed assays such as three-dimenionally (3D)-reconstituted skin models, an antioxidant response reporter assay, determination of signaling pathways, and gene profiling. Some of these assays show relatively high sensitivity and specificity for a large number of sensitizers and should enter validation (or are indeed entering this process). Integrating multiple assays in a decision tree or integrated testing system is a next step, but has yet to be developed. Adequate risk assessment, however, is likely to require significantly more time and efforts.

Improved micromethod for mezlocillin quantitation in serum and urine by high-pressure liquid chromatography.

PubMed Central

Fiore, D; Auger, F A; Drusano, G L; Dandu, V R; Lesko, L J

1984-01-01

A rapid, sensitive, and specific method of analysis for mezlocillin in serum and urine by high-pressure liquid chromatography is described. A solid-phase extraction column was used to remove interfering substances from samples before chromatography. Quantitation included the use of an internal standard, nafcillin. Mezlocillin was chromatographed with a phosphate buffer-acetonitrile (73:27) mobile phase and a C-18 reverse-phase column and detected at a wavelength of 220 nm. The assay had a sensitivity of 1.6 micrograms/ml and a linearity of up to 600 micrograms/ml and 16 mg/ml in serum and urine, respectively, with only 0.1 ml of sample. The interday and intraday coefficients of variation for replicate analyses of spiked serum and urine specimens were less than 6.5%. PMID:6517560

Conversion of depleted uranium hexafluoride to a solid uranium compound

DOEpatents

Rothman, Alan B.; Graczyk, Donald G.; Essling, Alice M.; Horwitz, E. Philip

2001-01-01

A process for converting UF.sub.6 to a solid uranium compound such as UO.sub.2 and CaF. The UF.sub.6 vapor form is contacted with an aqueous solution of NH.sub.4 OH at a pH greater than 7 to precipitate at least some solid uranium values as a solid leaving an aqueous solution containing NH.sub.4 OH and NH.sub.4 F and remaining uranium values. The solid uranium values are separated from the aqueous solution of NH.sub.4 OH and NH.sub.4 F and remaining uranium values which is then diluted with additional water precipitating more uranium values as a solid leaving trace quantities of uranium in a dilute aqueous solution. The dilute aqueous solution is contacted with an ion-exchange resin to remove substantially all the uranium values from the dilute aqueous solution. The dilute solution being contacted with Ca(OH).sub.2 to precipitate CaF.sub.2 leaving dilute NH.sub.4 OH.

Drug Target Interference in Immunogenicity Assays: Recommendations and Mitigation Strategies.

PubMed

Zhong, Zhandong Don; Clements-Egan, Adrienne; Gorovits, Boris; Maia, Mauricio; Sumner, Giane; Theobald, Valerie; Wu, Yuling; Rajadhyaksha, Manoj

2017-11-01

Sensitive and specific methodology is required for the detection and characterization of anti-drug antibodies (ADAs). High-quality ADA data enables the evaluation of potential impact of ADAs on the drug pharmacokinetic profile, patient safety, and efficacious response to the drug. Immunogenicity assessments are typically initiated at early stages in preclinical studies and continue throughout the drug development program. One of the potential bioanalytical challenges encountered with ADA testing is the need to identify and mitigate the interference mediated by the presence of soluble drug target. A drug target, when present at sufficiently high circulating concentrations, can potentially interfere with the performance of ADA and neutralizing antibody (NAb) assays, leading to either false-positive or, in some cases, false-negative ADA and NAb assay results. This publication describes various mechanisms of assay interference by soluble drug target, as well as strategies to recognize and mitigate such target interference. Pertinent examples are presented to illustrate the impact of target interference on ADA and NAb assays as well as several mitigation strategies, including the use of anti-target antibodies, soluble versions of the receptors, target-binding proteins, lectins, and solid-phase removal of targets. Furthermore, recommendations for detection and mitigation of such interference in different formats of ADA and NAb assays are provided.

Development of solid - based paper strips for rapid diagnosis of Pseudorabies infection.

PubMed

Joon Tam, Yew; Mohd Lila, Mohd Azmi; Bahaman, Abdul Rani

2004-12-01

Pseudorabies (Aujeszky's disease) is an economically significant disease of swine known to cause central nervous disorders, respiratory disease, reproductive failure and mortality in infected pigs. In attempts to eradicate the disease from becoming endemic, early detection is important to prevent further economic losses and to allow for detection and removal of infected pigs in domestic herds. Thus, a rapid and sensitive technique is necessary for the detection of the virus. For rapid and simple examination, an immuno - chromatographic lateral - flow assay system based on immunologic recognition of specific pseudorabies virus antigen was developed by utilising, as signal generator, colloidal gold conjugated to secondary antibody to detect primary or sample antibody in the sera of pseudorabies infected animals. The pseudorabies virus used as a capture antigen in the test strip was first cultivated in VERO cell culture and then purified by sucrose gradient separation to produce the viral protein concentration of 3.8 mg/ml. The standard pseudorabies antigens reacted well with the hyperimmune serum (HIS). The antibody detection system is basically composed of colloidal gold - labelled antibodies fixed on a conjugate pad, and the complementary pseudorabies antigen immobilised onto a nitrocellulose membrane forming capture zone. If the target antibody is present in a specimen, the colloidal gold-labelled antibody will form a complex with the antibody sample. Subsequently, the formed complex will migrate to the capture zone and is then bound to the solid phase via antigen - antibody interaction. As a result, a signal marker is generated by the accumulation of colloidal gold for detection confirmation. The results obtained demonstrated that the optimum combination of pseudorabies antigen needed as the capture reagent and gold conjugate as secondary antibody recognition marker was at a concentration of 0.38mg/ml and at 1:10 dilution factor respectively. The sensitivity of the solid - based test strip towards pseudorabies antibodies was high with a detection limit of 1 to 10,000 - dilution factor. The specificity of the assay was 100% with no cross - reaction being observed with other sera or antibodies. Accurate reading time needed for confirmation of the assay can be completed in 5 min with a whole blood sample of 25 microl. The colloidal gold - labelled antibody is stable at room temperature for 6 months or more (data not shown). Findings from this study indicated that the solid - based test strip assay system provided high sensitivity and specificity for the detection of pseudorabies at low levels of antibody concentration. The assay was rapid, simple, cheap, and does not require any sophisticated equipment. Thus, the solid based test strip will be a useful serological screening technique or for rapid diagnosis of an infectious disease in target populations of animals characterised by heterogeneous antibody responses.

The molecular bacterial load assay replaces solid culture for measuring early bactericidal response to antituberculosis treatment.

PubMed

Honeyborne, Isobella; Mtafya, Bariki; Phillips, Patrick P J; Hoelscher, Michael; Ntinginya, Elias N; Kohlenberg, Anke; Rachow, Andrea; Rojas-Ponce, Gabriel; McHugh, Timothy D; Heinrich, Norbert

2014-08-01

We evaluated the use of the molecular bacterial load (MBL) assay, for measuring viable Mycobacterium tuberculosis in sputum, in comparison with solid agar and liquid culture. The MBL assay provides early information on the rate of decline in bacterial load and has technical advantages over culture in either form. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Rapid Production of Mixed-Base Hydrogen Peroxide by Direct-Contact Liquefied Nitrogen Evaporation; Process Design, Scale-Up, and Validation

DTIC Science & Technology

2004-01-01

phase in November 1996. 1-2. BASIC HYDROGEN PEROXIDE In the early COIL work, either potassium hydroxide (KOH) or sodium hydroxide (NaOH) was the base of...the candidate refrigerants include: R22, R404a, R134a, carbon dioxide, and ammonia. 2-3-3. Surface Evaporator To improve the heat transfer efficiency...monohydrate (LiOH.H20), sodium hydroxide (NaOH), and potassium hydroxide (KOH). The use of solids allows numerous variations of blending sequence and heat

Unveiling the Switching Riddle of Silver Tetracyanoquinodimethane Towards Novel Planar Single-Crystalline Electrochemical Metallization Memories.

PubMed

Yang, Fangxu; Zhao, Qiang; Xu, Chunhui; Zou, Ye; Dong, Huanli; Zheng, Yonggang; Hu, Wenping

2016-09-01

The switching riddle of AgTCNQ is shown to be caused by the solid electrolyte mechanism. Both factors of bulk phase change and contact issue play key roles in the efficient work of the devices. An effective strategy is developed to locate the formation/disruption of Ag conductive filaments using the planar asymmetric configuration of Au/AgTCNQ/AlOx /Al. These novel electrochemical metallization memories demonstrate many promising properties. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solid lubrication design methodology, phase 2

NASA Technical Reports Server (NTRS)

Pallini, R. A.; Wedeven, L. D.; Ragen, M. A.; Aggarwal, B. B.

1986-01-01

The high temperature performance of solid lubricated rolling elements was conducted with a specially designed traction (friction) test apparatus. Graphite lubricants containing three additives (silver, phosphate glass, and zinc orthophosphate) were evaluated from room temperature to 540 C. Two hard coats were also evaluated. The evaluation of these lubricants, using a burnishing method of application, shows a reasonable transfer of lubricant and wear protection for short duration testing except in the 200 C temperature range. The graphite lubricants containing silver and zinc orthophosphate additives were more effective than the phosphate glass material over the test conditions examined. Traction coefficients ranged from a low of 0.07 to a high of 0.6. By curve fitting the traction data, empirical equations for slope and maximum traction coefficient as a function of contact pressure (P), rolling speed (U), and temperature (T) can be developed for each lubricant. A solid lubricant traction model was incorporated into an advanced bearing analysis code (SHABERTH). For comparison purposes, preliminary heat generation calculations were made for both oil and solid lubricated bearing operation. A preliminary analysis indicated a significantly higher heat generation for a solid lubricated ball bearing in a deep groove configuration. An analysis of a cylindrical roller bearing configuration showed a potential for a low friction solid lubricated bearing.

Analytical strategies for organic food packaging contaminants.

PubMed

Sanchis, Yovana; Yusà, Vicent; Coscollà, Clara

2017-03-24

In this review, we present current approaches in the analysis of food-packaging contaminants. Gas and liquid chromatography coupled to mass spectrometry detection have been widely used in the analysis of some relevant families of these compounds such as primary aromatic amines, bisphenol A, bisphenol A diglycidyl ether and related compounds, UV-ink photoinitiators, perfluorinated compounds, phthalates and non-intentionally added substances. Main applications for sample treatment and different types of food-contact material migration studies have been also discussed. Pressurized Liquid Extraction, Solid-Phase Microextraction, Focused Ultrasound Solid-Liquid Extraction and Quechers have been mainly used in the extraction of food contact material (FCM) contaminants, due to the trend of minimising solvent consumption, automatization of sample preparation and integration of extraction and clean-up steps. Recent advances in analytical methodologies have allowed unequivocal identification and confirmation of these contaminants using Liquid Chromatography coupled to High Resolution Mass Spectrometry (LC-HRMS) through mass accuracy and isotopic pattern applying. LC-HRMS has been used in the target analysis of primary aromatic amines in different plastic materials, but few studies have been carried out applying this technique in post-target and non-target analysis of FCM contaminants. Copyright © 2017 Elsevier B.V. All rights reserved.

Ultrapressure liquid chromatography-tandem mass spectrometry assay using atmospheric pressure photoionization (UPLC-APPI-MS/MS) for quantification of 4-methoxydiphenylmethane in pharmacokinetic evaluation.

PubMed

Farhan, Nashid; Fitzpatrick, Sean; Shim, Yun M; Paige, Mikell; Chow, Diana Shu-Lian

2016-09-05

4-Methoxydiphenylmethane (4-MDM), a selective augmenter of Leukotriene A4 Hydrolase (LTA4H), is a new anti-inflammatory compound for potential treatment of chronic obstructive pulmonary disease (COPD). Currently, there is no liquid chromatography tandem mass spectrometric (LC-MS/MS) method for the quantification of 4-MDM. A major barrier for developing the LC-MS/MS method is the inability of electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) to ionize 4-MDM due to its hydrophobicity and lack of any functional group for ionization. With the advent of atmospheric pressure photoionization (APPI) technique, many hydrophobic compounds have been demonstrated to ionize by charge transfer reactions. In this study, a highly sensitive ultrapressure liquid chromatography tandem mass spectrometry assay using atmospheric pressure photoionization (UPLC-APPI-MS/MS) for the quantifications of 4-MDM in rat plasma has been developed and validated. 4-MDM was extracted from the plasma by solid phase extraction (SPE) and separated chromatographically using a reverse phase C8 column. The photoionization (PI) was achieved by introducing anisole as a dopant to promote the reaction of charge transfer. The assay with a linear range of 5 (LLOQ)-400ngmL(-1) met the regulatory requirements for accuracy, precision and stability. The validated assay was employed to quantify the plasma concentrations of 4-MDM after an oral dosing in Sprague Dawley (SD) rats. Copyright © 2016 Elsevier B.V. All rights reserved.

Novel liquid chromatographic assay for the low-level determination of apomorphine in plasma.

PubMed

Priston, M J; Sewell, G J

1996-05-31

A novel HPLC assay which is rapid, reproducible and sensitive has been developed for the analysis of apomorphine in plasma. The assay incorporates boldine as an internal standard, and uses solid-phase extraction on C18 mini-columns for sample clean-up and concentration, so enabling quantitation of apomorphine at 500 pg/ml using fluorescence detection (lambda(ex) 270 nm, lambda(em) 450 nm). The HPLC assay comprised a 25 cm-long Techopak C18 column and a mobile phase of (0.25 M sodium dihydrogen phosphate plus 0.25% heptane sulphonic acid, to pH 3.3 with orthophosphoric acid) containing 30% (v/v) methanol and 0.003% (w/v) EDTA, run at a flow-rate of 1.5 ml/min. Calibration plots prepared in plasma were linear over the range 1-30 ng/ml, (limit of quantitation (LOQ) = 490 pg/ml) with R.S.D. of 0.05% and R.E. of 5.0% at the level of 1 ng/ml. Preliminary pharmacokinetic data from two patients given apomorphine by 12 h subcutaneous infusion (patient A dose = 35 mg and patient B dose = 141 mg) showed apomorphine elimination from plasma to fit a two-compartment model, with initial half-lives of 8.2 and 46.6 min, elimination half-lives of 76.4 and 166.5 min and area under the plasma concentration-time curve (AUC) values of 236 and 405 ng h/ml, respectively.

The combined SPE:ToxY-PAM phytotoxicity assay; application and appraisal of a novel biomonitoring tool for the aquatic environment.

PubMed

Bengtson Nash, S M; Schreiber, U; Ralph, P J; Müller, J F

2005-01-15

Mounting concerns regarding the environmental impact of herbicides has meant a growing requirement for accurate, timely information regarding herbicide residue contamination of, in particular, aquatic systems. Conventional methods of detection remain limited in terms of practicality due to high costs of operation and the specialised information that analysis provides. A new phytotoxicity bioassay was trialled for the detection of herbicide residues in filter-purified (Milli-Q) as well as natural waters. The performance of the system, which combines solid-phase extraction (SPE) with the ToxY-PAM dual-channel yield analyser (Heinz Walz GmbH), was tested alongside the traditional method of liquid chromatography-mass spectrometry (LC-MS). The assay methodology was found to be highly sensitive (LOD 0.1 ng L(-1) diuron) with good reproducibility. The study showed that the assay protocol is time effective and can be employed for the aquatic screening of herbicide residues in purified as well as natural waters.

Microbial identification by immunohybridization assay of artificial RNA labels

NASA Technical Reports Server (NTRS)

Kourentzi, Katerina D.; Fox, George E.; Willson, Richard C.

2002-01-01

Ribosomal RNA (rRNA) and engineered stable artificial RNAs (aRNAs) are frequently used to monitor bacteria in complex ecosystems. In this work, we describe a solid-phase immunocapture hybridization assay that can be used with low molecular weight RNA targets. A biotinylated DNA probe is efficiently hybridized in solution with the target RNA, and the DNA-RNA hybrids are captured on streptavidin-coated plates and quantified using a DNA-RNA heteroduplex-specific antibody conjugated to alkaline phosphatase. The assay was shown to be specific for both 5S rRNA and low molecular weight (LMW) artificial RNAs and highly sensitive, allowing detection of as little as 5.2 ng (0.15 pmol) in the case of 5S rRNA. Target RNAs were readily detected even in the presence of excess nontarget RNA. Detection using DNA probes as small as 17 bases targeting a repetitive artificial RNA sequence in an engineered RNA was more efficient than the detection of a unique sequence.

Influence of an americium solid phase on americium concentrations in solutions

NASA Astrophysics Data System (ADS)

Rai, Dhanpat; Strickert, R. G.; Moore, D. A.; Serne, R. J.

1981-11-01

Americium-241 concentrations in solutions contacting contaminated sediments for up to 2 yr were measured as a function of pH. Steady-state concentrations were reached within a few days. The solubility-limited Am concentration was found to decrease approximately 10-fold with one unit increase in pH. The log equilibrium constant for the solubility of Am (soil) solid [Am (soil) + H + ⇌ Am (aq complex)+] was found to be -4.12. The predictions based upon thermodynamic data suggest that Am (aq complex)+ is likely to be Am(OH) 2+. Although the chemical formula of Am (soil) was not determined, it does not appear to be Am(OH) 3(a). Published data on sorption coefficients of Am by different rocks, soils, and minerals were critically evaluated. Final Am solution concentrations calculated from the sorption coefficients of a variety of earth materials with several solutions agreed well with the concentrations predicted from the solubility of Am (soil) solid, indicating that the sorption coefficient data are controlled by Am precipitation.

An innovative method for analysis of Pb (II) in rice, milk and water samples based on TiO2 reinforced caprylic acid hollow fiber solid/liquid phase microextraction.

PubMed

Bahar, Shahriyar; Es'haghi, Zarrin; Nezhadali, Azizollah; Banaei, Alireza; Bohlooli, Shahab

2017-04-15

In the present study, nano-sized titanium oxides were applied for preconcentration and determination of Pb(II) in aqueous samples using hollow fiber based solid-liquid phase microextraction (HF-SLPME) combined with flame atomic absorption spectrometry (FAAS). In this work, the nanoparticles dispersed in caprylic acid as an extraction solvent was placed into a polypropylene porous hollow fiber segment supported by capillary forces and sonification. This membrane was in direct contact with solutions containing Pb (II). The effect of experimental conditions on the extraction, such as pH, stirring rate, sample volume, and extraction time were optimized. Under the optimal conditions, the performance of the proposed method was investigated for the determination of Pb (II) in food and water samples. The method was linear in the range of 0.6-3000μgmL -1 . The relative standard deviations and relative recovery of Pb (II) was 4.9% and 99.3%, respectively (n=5). Copyright © 2016 Elsevier Ltd. All rights reserved.

Near Axisymmetric Partial Wetting Using Interface-Localized Liquid Dielectrophoresis.

PubMed

Brabcova, Zuzana; McHale, Glen; Wells, Gary G; Brown, Carl V; Newton, Michael I; Edwards, Andrew M J

2016-10-25

The wetting of solid surfaces can be modified by altering the surface free energy balance between the solid, liquid, and vapor phases. Liquid dielectrophoresis (L-DEP) can produce wetting on normally nonwetting surfaces, without modification of the surface topography or chemistry. L-DEP is a bulk force acting on the dipoles of a dielectric liquid and is not normally considered to be a localized effect acting at the interface between the liquid and a solid or other fluid. However, if this force is induced by a nonuniform electric field across a solid-liquid interface, it can be used to enhance and control the wetting of a dielectric liquid. Recently, it was reported theoretically and experimentally that this approach can cause a droplet of oil to spread along parallel interdigitated electrodes thus forming a stripe of liquid. Here we show that by using spiral-shaped electrodes actuated with four 90° successive phase-shifted signals, a near axisymmetric spreading of droplets can be achieved. Experimental observations show that the induced wetting can achieve film formation, an effect not possible with electrowetting. We show that the spreading is reversible thus enabling a wide range of partial wetting droplet states to be achieved in a controllable manner. Furthermore, we find that the cosine of the contact angle has a quadratic dependence on applied voltage during spreading and deduce a scaling law for the dependence of the strength of the effect on the electrode size.

Theoretical model of droplet wettability on a low-surface-energy solid under the influence of gravity.

PubMed

Yonemoto, Yukihiro; Kunugi, Tomoaki

2014-01-01

The wettability of droplets on a low surface energy solid is evaluated experimentally and theoretically. Water-ethanol binary mixture drops of several volumes are used. In the experiment, the droplet radius, height, and contact angle are measured. Analytical equations are derived that incorporate the effect of gravity for the relationships between the droplet radius and height, radius and contact angle, and radius and liquid surface energy. All the analytical equations display good agreement with the experimental data. It is found that the fundamental wetting behavior of the droplet on the low surface energy solid can be predicted by our model which gives geometrical information of the droplet such as the contact angle, droplet radius, and height from physical values of liquid and solid.

A new approach for downscaling of electromembrane extraction as a lab on-a-chip device followed by sensitive Red-Green-Blue detection.

PubMed

Baharfar, Mahroo; Yamini, Yadollah; Seidi, Shahram; Arain, Muhammad Balal

2018-05-30

A new design of electromembrane extraction (EME) as a lab on-a-chip device was proposed for the extraction and determination of phenazopyridine as the model analyte. The extraction procedure was accomplished by coupling of EME and the packing of a sorbent. The analyte was extracted under the applied electrical field across a membrane sheet impregnated by nitrophenyl octylether (NPOE) into an acceptor phase. It was followed by the absorption of the analyte on strong cation exchanger as a sorbent. The designed chip contained separate spiral channels for donor and acceptor phases featuring embedded platinum electrodes to enhance extraction efficiency. The selected donor and acceptor phases were 0 mM HCl and 100 mM HCl, respectively. The on-chip electromembrane extraction was carried out under the voltage level of 70 V for 50 min. The analysis was carried out by two modes of a simple Red-Green-Blue (RGB) image analysis tool and a conventional HPLC-UV system. After the absorption of the analyte on the solid phase, its color changed and a digital picture of the sorbent was taken for the RGB analysis. The effective parameters on the performance of the chip device, comprising the EME and solid phase microextraction steps, were distinguished and optimized. The accumulation of the analyte on the solid phase showed excellent sensitivity and a limit of detection (LOD) lower than 1.0 μg L-1 achieved by an image analysis using a smartphone. This device also offered acceptable intra- and inter-assay RSD% (<10%). The calibration curves were linear within the range of 10-1000 μg L-1 and 30-1000 μg L-1 (r2 > 0.9969) for HPLC-UV and RGB analysis, respectively. To investigate the applicability of the method in complicated matrices, urine samples of patients being treated with phenazopyridine were analyzed.

HPLC–electrospray mass spectrometric assay for the determination of (R,R)-fenoterol in rat plasma

PubMed Central

Siluk, Danuta; Kim, Hee Seung; Cole, Tyler; Wainer, Irving W.

2008-01-01

A fast and specific liquid chromatography–mass spectrometry method for the determination of (R,R)-fenoterol ((R,R)-Fen) in rat plasma has been developed and validated. (R,R)-Fen was extracted from 125 µl of plasma using solid phase extraction and analyzed on Atlantis HILIC Silica 3 µm column. The mobile phase was composed of acetonitrile:ammonium acetate (pH 4.1; 20 mM) (85:15, v/v), at a flow rate of 0.2 ml/min. The lower limit of detection (LLOD) was 2 ng/ml . The procedure was validated and applied to the analysis of plasma samples from rats previously administered (R,R)-Fen in an intravenous bolus. PMID:18617349

Dispositional study of opioids in mice pretreated with sympathomimetic agents.

PubMed

Dambisya, Y M; Chan, K; Wong, C L

1992-08-01

Brain and plasma levels of morphine and codeine were determined by an assay method involving solid-phase extraction and ion-pair reversed phase HPLC. Detection was by a variable wavelength UV-detector (for codeine) and an amperometric electro-chemical detector (for morphine) coupled in series. Ephedrine or phenylpropanolamine pretreatment did not interfere with the plasma disposition of morphine, evidenced by overlapping plasma concentration-time profiles. Brain opioid levels were equally unaffected by sympathomimetic pretreatment. The relative ratios of brain to plasma concentrations at the time corresponding to the respective peak anti-nociceptive activity for morphine and codeine revealed no significant differences. It is concluded that single doses of ephedrine and phenylpropanolamine do not affect the disposition of morphine and codeine in mice.

High-performance liquid chromatography measurement of hyperforin and its reduced derivatives in rodent plasma.

PubMed

Rozio, M; Fracasso, C; Riva, A; Morazzoni, P; Caccia, S

2005-02-25

A reverse-phase high-performance liquid chromatography method was developed for the determination of hyperforin and its reduced derivatives octahydrohyperforin and tetrahydrohyperforin in rodent plasma. The procedure includes solid-phase extraction from plasma using the Baker 3cc C8 cartridge, resolution on the Symmetry Shield RP8 column (150 mm x 4.6 mm, i.d. 3.5 microm) and UV absorbance detection at 300 nm. The assay was linear over a wide range, with an overall coefficient of variation less than 10% for all compounds. The precision and accuracy were within acceptable limits and the limit of quantitation was sufficient for studies preliminarily assessing the disposition of tetrahydrohyperforin and octahydrohyperforin in the mouse and rat.

Multi-Phase Field Models and Microstructural Evolution with Applications in Fuel Cell Technology

NASA Astrophysics Data System (ADS)

Davis, Ryan Scott

The solid oxide fuel cell (SOFC) has shown tremendous potential as an efficient energy conversion device that may be instrumental in the transition to renewable resources. However, commercialization is hindered by many degradation mechanisms that plague long term stability. In this dissertation, computation methods are used to explore the relationship between the microstructure of the fuel cell anode and performance critical metrics. The phase field method and standard modeling procedures are introduced using a classic model of spinodal decomposition. This is further developed into a complete, multi-phase modeling framework designed for the complex microstructural evolution of SOFC anode systems. High-temperature coarsening of the metallic phase in the state-of-the-art SOFC cermet anode is investigated using our phase field model. A systematic study into the effects of interface properties on microstructural evolution is accomplished by altering the contact angle between constituent phases. It is found that metrics of catalytic activity and conductivity display undesirable minima near the contact angle of conventional SOFC materials. These results suggest that tailoring the interface properties of the constituent phases could lead to a significant increase in the performance and lifetime of SOFCs. Supported-metal catalyst systems are investigated in the first detailed study of their long-term stability and application to SOFC anode design. Porous support structures are numerically sintered to mimic specific fabrication techniques, and these structures are then infiltrated with a nanoscale catalyst phase ranging from 2% to 21% loading. Initially, these systems exhibit enhanced potential for catalytic activity relative to conventional cells. However, extended evolution results in severe degradation, and we show that Ostwald ripening and particle migration are key kinetic processes. Strong geometric heterogeneity in the support structure via a novel approach to nanopore formation is proposed as a potential solution for catalyst stabilization.

A monoclonal antibody specific for Δ12-prostaglandin J2 and its utilization in the immunological assay in cell culture system of adipocytes.

PubMed

Syeda, Pinky Karim; Hossain, Mohammad Salim; Chowdhury, Abu Asad; Rahman, Mohammad Sharifur; Khan, Ferdous; Nishimura, Kohji; Jisaka, Mitsuo; Nagaya, Tsutomu; Shono, Fumiaki; Yokota, Kazushige

2012-10-01

Prostaglandin (PG) D(2) can be produced in adipocytes and dehydrated to PGs of J(2) series, including Δ(12)-PGJ(2) and 15-deoxy-Δ(12,14)-PGJ(2) (15d-PGJ(2)), which serve as pro-adipogenic prostanoids through the activation of peroxisome proliferator-activated receptor γ. To accomplish the quantification of Δ(12)-PGJ(2) in the cell culture system of adipocytes, the present study aimed to develop a sensitive and specific immunological assay for Δ(12)-PGJ(2). Here, we established a cloned hybridoma cell line secreting a monoclonal antibody specifically recognizing Δ(12)-PGJ(2) and utilized for the development of its solid-phase enzyme-linked immunosorbent assay (ELISA). The immobilized antigen using a conjugate of Δ(12)-PGJ(2) and γ-globulin was competitively allowed to react with the monoclonal antibody in the presence of free Δ(12)-PGJ(2). The assay provided a sensitive calibration curve for Δ(12)-PGJ(2), allowing us to determine a range from 0.16 pg to 0.99 ng with a value of 13 pg at 50% displacement in one assay. The monoclonal antibody showed almost no cross-reactivity with other related prostanoids since PGJ(2) and 15d-PGJ(2) were only recognized with much lower values of 0.5% and 0.2%, respectively. The accuracy for determining Δ(12)-PGJ(2) in the culture medium of adipocytes was confirmed by measurement after the culture medium was fortified with known amounts of authentic Δ(12)-PGJ(2) in a range from 10 to 200 pg/mL. The application of our ELISA revealed that the formation of Δ(12)-PGJ(2) became more pronounced after several hours of incubation of PGD(2) at 37°C in fresh maturation medium of cultured adipocytes. Furthermore, we provide evidence for the increased ability of cultured adipocytes to synthesize endogenous Δ(12)-PGJ(2) during the progression of adipogenesis. These results indicate the reliability and usefulness of our solid-phase ELISA for stable Δ(12)-PGJ(2), reflecting the biosynthesis of unstable PGD(2) in the culture system of adipocytes.

Evaluating behavior of oxygen, nitrate, and sulfate during recharge and quantifying reduction rates in a contaminated aquifer

USGS Publications Warehouse

McGuire, Jennifer T.; Long, David T.; Klug, Michael J.; Haack, Sheridan K.; Hyndman, David W.

2002-01-01

This study evaluates the biogeochemical changes that occur when recharge water comes in contact with a reduced aquifer. It specifically addresses (1) which reactions occur in situ, (2) the order in which these reactions will occur if terminal electron acceptors (TEAs) are introduced simultaneously, (3) the rates of these reactions, and (4) the roles of the aqueous and solid-phase portions of the aquifer. Recharge events of waters containing various combinations of O2, NO3, and SO4 were simulated at a shallow sandy aquifer contaminated with waste fuels and chlorinated solvents using modified push−pull tests to quantify rates. In situ rate constants for aerobic respiration (14.4 day -1), denitrification (5.04−7.44 day-1), and sulfate reduction (4.32−6.48 day-1) were estimated. Results show that when introduced together, NO3 and SO4can be consumed simultaneously at similar rates. To distinguish the role of aqueous phase from that of the solid phase of the aquifer, groundwater was extracted, amended with NO3 and SO4, and monitored over time. Results indicate that neither NO3 nor SO4 was reduced during the course of the aqueous-phase study, suggesting that NO3 and SO4 can behave conservatively in highly reduced water. It is clear that sediments and their associated microbial communities are important in driving redox reactions.

31P and 1H NMR Studies of the Molecular Organization of Lipids in the Parallel Artificial Membrane Permeability Assay.

PubMed

Assmus, Frauke; Ross, Alfred; Fischer, Holger; Seelig, Joachim; Seelig, Anna

2017-01-03

The parallel artificial membrane permeability assay (PAMPA) has emerged as a widely used primary in vitro screen for passive permeability of potential drug candidates. However, the molecular structure of the permeation barrier (consisting of a filter-supported dodecane-egg lecithin mixture) has never been characterized. Here, we investigated the long-range order of phospholipids in the PAMPA barrier by means of 31 P static solid-state NMR. Diffusion constants of PAMPA membrane components were derived from liquid state NMR and, in addition, drug distribution between the PAMPA lipid phase and buffer (log D PAMPA at pH 7.4) was systematically investigated. Increasing concentration of n-dodecane to the system egg lecithin-water (lamellar phase, L α ) induces formation of inverted hexagonal (H ii ) and isotropic phases. At n-dodecane concentrations matching those used in PAMPA (9%, w/v) a purely "isotropic" phase was observed corresponding to lipid aggregates with a diameter in the range 4-7 nm. Drug distribution studies indicate that these reverse micelles facilitate the binding to, and in turn the permeation across, the PAMPA dodecane barrier, in particular for amphiphilic solutes. The proposed model for the molecular architecture and function of the PAMPA barrier provides a fundamental, hitherto missing framework to evaluate the scope but also limitations of PAMPA for the prediction of in vivo membrane permeability.

Stack configurations for tubular solid oxide fuel cells

DOEpatents

Armstrong, Timothy R.; Trammell, Michael P.; Marasco, Joseph A.

2010-08-31

A fuel cell unit includes an array of solid oxide fuel cell tubes having porous metallic exterior surfaces, interior fuel cell layers, and interior surfaces, each of the tubes having at least one open end; and, at least one header in operable communication with the array of solid oxide fuel cell tubes for directing a first reactive gas into contact with the porous metallic exterior surfaces and for directing a second reactive gas into contact with the interior surfaces, the header further including at least one busbar disposed in electrical contact with at least one surface selected from the group consisting of the porous metallic exterior surfaces and the interior surfaces.

The dependency of adhesion and friction on electrostatic attraction

NASA Astrophysics Data System (ADS)

Persson, B. N. J.

2018-04-01

I develop a general mean-field theory for the influence of electrostatic attraction between two solids on the contact mechanics. I assume elastic solids with random surface roughness. I consider two cases, namely, with and without an electrically insulating layer between the conducting solids. The former case is important for, e.g., the finger-touch screen interaction. I study how the electrostatic attraction influences the adhesion and friction. For the case of an insulating layer, I find that when the applied nominal contact pressure is relatively small, as the applied voltage increases, there is a sharp increase in the contact area, and hence in the friction, at a critical voltage.

Preparation of curcumin self-micelle solid dispersion with enhanced bioavailability and cytotoxic activity by mechanochemistry.

PubMed

Zhang, Qihong; Polyakov, Nikolay E; Chistyachenko, Yulia S; Khvostov, Mikhail V; Frolova, Tatjana S; Tolstikova, Tatjana G; Dushkin, Alexandr V; Su, Weike

2018-11-01

An amorphous solid dispersion (SD) of curcumin (Cur) with disodium glycyrrhizin (Na 2 GA) was prepared by mechanical ball milling. Curcumin loaded micelles were self-formed by Na 2 GA when SD dissolved in water. The physical properties of Cur SD in solid state were characterized by differential scanning calorimetry, X-ray diffraction studies, and scanning electron microscope. The characteristics of the sample solutions were analyzed by reverse phase HPLC, UV-visible spectroscopy, 1 H NMR spectroscopy, gel permeation LC, and transmission electron microscopy. In vitro cytotoxic tests demonstrated that Cur SD induced higher cytotoxicity against glioblastoma U-87 MG cells than free Cur. Besides, an improvement of membrane permeability of Cur SD was confirmed by parallel artificial membrane permeability assay. Further pharmacokinetic study of this SD formulation in rat showed a significant ∼19-fold increase of bioavailability as comparing to free Cur. Thus, Cur SD provide a more potent and efficacious formulation for Cur oral delivery.

Silica aerogel coated on metallic wire by phase separation of polystyrene for in-tube solid phase microextraction.

PubMed

Baktash, Mohammad Yahya; Bagheri, Habib

2017-06-02

In this research, an attempt was made toward synthesizing a sol-gel-based silica aerogel and its subsequent coating on a copper wire by phase separation of polystyrene. Adaption of this new approach enabled us to coat the metallic wire with powder materials. The use of this method for coating, led to the formation of a porous and thick structure of silica aerogel. The coated wire was placed in a needle and used as the sorbent for in-tube solid phase microextraction of chlorobenzenes (CBs). The superhydrophobicity of sorbent on extraction efficiency was investigated by using different ratios of tetraethylorthosilicate/methyltrimethoxysilane. The surface coated with the prepared silica aerogel by the phase separation of polystyrene showed high contact angle, approving the desired superhydrophobic properties. Effects of major parameters influencing the extraction efficiency including the extraction temperature, extraction time, ionic strength, desorption time were investigated and optimized. The limits of detection and quantification of the method under the optimized condition were 0.1-1.2 and 0.4-4.1ngL -1 , respectively. The relative standard deviations (RSD%) at a concentration level of 10ngL -1 were between 4 and 10% (n=3). The calibration curves of CBs showed linearity from 1 to100ngL -1 . Eventually, the method was successfully applied to the extraction of model compounds from real water samples and relative recoveries varied from 88 to 115%. Copyright © 2017 Elsevier B.V. All rights reserved.

Electropolymerized fluorinated aniline-based fiber for headspace solid-phase microextraction and gas chromatographic determination of benzaldehyde in injectable pharmaceutical formulations.

PubMed

Mohammadi, Ali; Mohammadi, Somayeh; Bayandori Moghaddam, Abdolmajid; Masoumi, Vahideh; Walker, Roderick B

2014-10-01

In this study, a simple method was developed and validated to detect trace levels of benzaldehyde in injectable pharmaceutical formulations by solid-phase microextraction coupled with gas chromatography-flame ionization detector. Polyaniline was electrodeposited on a platinum wire in trifluoroacetic acid solvent by cyclic voltammetry technique. This fiber shows high thermal and mechanical stability and high performance in extraction of benzaldehyde. Extraction and desorption time and temperature, salt effect and gas chromatography parameters were optimized as key parameters. At the optimum conditions, the fiber shows good linearity between peak area ratio of benzaldehyde/3-chlorobenzaldehyde and benzaldehyde concentration in the range of 50-800 ng/mL with percent relative standard deviation values ranging from 0.75 to 8.64% (n = 3). The limits of quantitation and detection were 50 and 16 ng/mL, respectively. The method has the requisite selectivity, sensitivity, accuracy and precision to assay benzaldehyde in injectable pharmaceutical dosage forms. © The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Evaluation of the solid phase competition ELISA for detecting antibodies against the six foot-and-mouth disease virus non-O serotypes.

PubMed

Li, Yanmin; Swabey, Kate G; Gibson, Debi; Keel, Phil J; Hamblin, Pip; Wilsden, Ginette; Corteyn, Mandy; Ferris, Nigel P

2012-08-01

The solid-phase competition ELISA (SPCE) has been evaluated in both screening and titration assay formats for detecting antibodies against foot-and-mouth disease virus (FMDV) for the six non-O serotypes A, C, SAT 1, SAT 2, SAT 3 and Asia 1. Cut-off values were determined as a percentage inhibition of 40 for the SAT serotypes and 50 for serotypes A, C and Asia 1, which gave rise to specificity values ranging from 99.41% to 99.9% for the different serotypes. The relative sensitivity between the SPCE and LPBE/virus neutralisation test was 100%/109%. Antiserum titres derived by the SPCE for samples of serotypes O, A(22) and Asia 1 were more than 11, 1 and 5 times of those determined by virus neutralisation test, respectively. This study indicated that the non-type O SPCEs have sufficient sensitivities and specificities for use as serological diagnostic tests for the qualitative and quantitative detection of antibodies against FMDV. Copyright © 2012 Elsevier B.V. All rights reserved.

Formation of bubbly horizon in liquid-saturated porous medium by surface temperature oscillation.

PubMed

Goldobin, Denis S; Krauzin, Pavel V

2015-12-01

We study nonisothermal diffusion transport of a weakly soluble substance in a liquid-saturated porous medium in contact with a reservoir of this substance. The surface temperature of the porous medium half-space oscillates in time, which results in a decaying solubility wave propagating deep into the porous medium. In this system, zones of saturated solution and nondissolved phase coexist with ones of undersaturated solution. The effect is first considered for the case of annual oscillation of the surface temperature of water-saturated ground in contact with the atmosphere. We reveal the phenomenon of formation of a near-surface bubbly horizon due to temperature oscillation. An analytical theory of the phenomenon is developed. Further, the treatment is extended to the case of higher frequency oscillations and the case of weakly soluble solids and liquids.

Control valve and control valve system for controlling solids flow, methods of manufacture thereof and articles comprising the same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jukkola, Glen D.; Teigen, Bard C.

Disclosed herein is a solids flow control valve comprising a standpipe; a shoe; and a transport pipe; wherein the standpipe is in operative communication with the shoe and lies upstream of the shoe; the standpipe comprising a first end and a second end, where the first end is in contact with a source that contains disposable solids and the second end is in fluid contact with the shoe; the shoe being operative to restrict the flow of the disposable solids; the transport pipe being disposed downstream of the shoe to receive and transport the solids from the shoe.

Two dimensional modeling of elastic wave propagation in solids containing cracks with rough surfaces and friction - Part II: Numerical implementation.

PubMed

Delrue, Steven; Aleshin, Vladislav; Truyaert, Kevin; Bou Matar, Olivier; Van Den Abeele, Koen

2018-01-01

Our study aims at the creation of a numerical toolbox that describes wave propagation in samples containing internal contacts (e.g. cracks, delaminations, debondings, imperfect intergranular joints) of known geometry with postulated contact interaction laws including friction. The code consists of two entities: the contact model and the solid mechanics module. Part I of the paper concerns an in-depth description of a constitutive model for realistic contacts or cracks that takes into account the roughness of the contact faces and the associated effects of friction and hysteresis. In the crack model, three different contact states can be recognized: contact loss, total sliding and partial slip. Normal (clapping) interactions between the crack faces are implemented using a quadratic stress-displacement relation, whereas tangential (friction) interactions were introduced using the Coulomb friction law for the total sliding case, and the Method of Memory Diagrams (MMD) in case of partial slip. In the present part of the paper, we integrate the developed crack model into finite element software in order to simulate elastic wave propagation in a solid material containing internal contacts or cracks. We therefore implemented the comprehensive crack model in MATLAB® and introduced it in the Structural Mechanics Module of COMSOL Multiphysics®. The potential of the approach for ultrasound based inspection of solids with cracks showing acoustic nonlinearity is demonstrated by means of an example of shear wave propagation in an aluminum sample containing a single crack with rough surfaces and friction. Copyright © 2017 Elsevier B.V. All rights reserved.

Small molecule antagonists of the urokinase (uPA): urokinase receptor (uPAR) interaction with high reported potencies show only weak effects in cell-based competition assays employing the native uPAR ligand.

PubMed

De Souza, Melissa; Matthews, Hayden; Lee, Jodi A; Ranson, Marie; Kelso, Michael J

2011-04-15

Binding of the urokinase-type plasminogen activator (uPA) to its cell-surface-bound receptor uPAR and upregulation of the plasminogen activation system (PAS) correlates with increased metastasis and poor prognosis in several tumour types. Disruptors of the uPA:uPAR interaction represent promising anti-tumour/metastasis agents and several approaches have been explored for this purpose, including the use of small molecule antagonists. Two highly potent non-peptidic antagonists 1 and 2 (IC(50)1=0.8 nM, IC(50)2=33 nM) from the patent literature were reportedly identified using competition assays employing radiolabelled uPAR-binding uPA fragments and appeared as useful pharmacological tools for studying the PAS. Before proceeding to such studies, confirmation was sought that 1 and 2 retained their potencies in physiologically relevant cell-based competition assays employing uPAR's native binding partner high molecular weight uPA (HMW-uPA). This study describes a new solution phase synthesis of 1, a mixed solid/solution phase synthesis of 2 and reports the activities of 1 and 2 in semi-quantitative competition flow cytometry assays and quantitative cell-based uPA activity assays that employed HMW-uPA as the competing ligand. The flow cytometry experiments revealed that high concentrations of 2 (10-100 μM) are required to compete with HMW-uPA for uPAR binding and that 1 shows no antagonist effects at 100 μM. The cell-based enzyme activity assays similarly revealed that 1 and 2 are poor inhibitors of cell surface-bound HMW-uPA activity (IC(50) >100 μM for 1 and 2). The report highlights the dangers of identifying false-positive lead uPAR antagonists from competition assays employing labelled competing ligands other than the native HMW-uPA. Copyright © 2011 Elsevier Ltd. All rights reserved.

A laboratory study of the nucleation kinetics of nitric acid hydrates under stratospheric conditions

NASA Astrophysics Data System (ADS)

James, Alexander D.; Murray, Benjamin J.; Plane, John M. C.

2016-04-01

Measurements of the kinetics of crystallisation of ternary H2O-H2SO4-HNO3 mixtures to produce nitric acid hydrate phases, as occurs in the lower stratosphere, have been a long-standing challenge for investigators in the laboratory. Understanding polar stratospheric chlorine chemistry and thereby ozone depletion is increasingly limited by descriptions of nucleation processes. Meteoric smoke particles have been considered in the past as heterogeneous nuclei, however recent studies suggest that these particles will largely dissolve, leaving mainly silica and alumina as solid inclusions. In this study the nucleation kinetics of nitric acid hydrate phases have been measured in microliter droplets at polar stratospheric cloud (PSC) temperatures, using a droplet freezing assay. A clear heterogeneous effect was observed when silica particles were added. A parameterisation based on the number of droplets activated per nuclei surface area (ns) has been developed and compared to global model data. Nucleation experiments on identical droplets have been performed in an X-Ray Diffractometer (XRD) to determine the nature of the phase which formed. β-Nitric Acid Trihydrate (NAT) was observed alongside a mixture of Nitric Acid Dihydrate (NAD) phases. It is not possible to determine whether NAT nucleates directly or is formed by a phase transition from NAD (likely requiring the presence of a mediating liquid phase). Regardless, these results demonstrate the possibility of forming NAT on laboratory timescales. In the polar stratosphere, sulfuric acid (present at several weight percent of the liquid under equilibrium conditions) could provide such a liquid phase. This study therefor provides insight into previous discrepancies between phases formed in the laboratory and those observed in the atmosphere. It also provides a basis for future studies into atmospheric nucleation of solid PSCs.

Impact of assay design on test performance: lessons learned from 25-hydroxyvitamin D.

PubMed

Farrell, Christopher-John L; Soldo, Joshua; McWhinney, Brett; Bandodkar, Sushil; Herrmann, Markus

2014-11-01

Current automated immunoassays vary significantly in many aspects of their design. This study sought to establish if the theoretical advantages and disadvantages associated with different design formats of automated 25-hydroxyvitamin D (25-OHD) assays are translated into variations in assay performance in practice. 25-OHD was measured in 1236 samples using automated assays from Abbott, DiaSorin, Roche and Siemens. A subset of 362 samples had up to three liquid chromatography-tandem mass spectrometry 25-OHD analyses performed. 25-OHD₂ recovery, dilution recovery, human anti-animal antibody (HAAA) interference, 3-epi-25-OHD₃ cross-reactivity and precision of the automated assays were evaluated. The assay that combined release of 25-OHD with analyte capture in a single step showed the most accurate 25-OHD₂ recovery and the best dilution recovery. The use of vitamin D binding protein (DBP) as the capture moiety was associated with 25-OHD₂ under-recovery, a trend consistent with 3-epi-25-OHD₃ cross-reactivity and immunity to HAAA interference. Assays using animal-derived antibodies did not show 3-epi-25-OHD₃ cross-reactivity but were variably susceptible to HAAA interference. Not combining 25-OHD release and capture in one step and use of biotin-streptavidin interaction for solid phase separation were features of the assays with inferior accuracy for diluted samples. The assays that used a backfill assay format showed the best precision at high concentrations but this design did not guarantee precision at low 25-OHD concentrations. Variations in design among automated 25-OHD assays influence their performance characteristics. Consideration of the details of assay design is therefore important when selecting and validating new assays.

Atomistic Interface Dynamics in Sn-Catalyzed Growth of Wurtzite and Zinc-Blende ZnO Nanowires.

PubMed

Jia, Shuangfeng; Hu, Shuaishuai; Zheng, He; Wei, Yanjie; Meng, Shuang; Sheng, Huaping; Liu, Huihui; Zhou, Siyuan; Zhao, Dongshan; Wang, Jianbo

2018-06-11

Unraveling the phase selection mechanisms of semiconductor nanowires (NWs) is critical for the applications in future advanced nanodevices. In this study, the atomistic vapor-solid-liquid growth processes of Sn-catalyzed wurtzite (WZ) and zinc blende (ZB) ZnO are directly revealed based on the in situ transmission electron microscopy. The growth kinetics of WZ and ZB crystal phases in ZnO appear markedly different in terms of the NW-droplet interface, whereas the nucleation site as determined by the contact angle ϕ between the seed particle and the NW is found to be crucial for tuning the NW structure through combined experimental and theoretical investigations. These results offer an atomic-scale view into the dynamic growth process of ZnO NW, which has implications for the phase-controllable synthesis of II-VI compounds and heterostructures with tunable band structures.

Characterization and quantitation of PVP content in a silicone hydrogel contact lens produced by dual-phase polymerization processing.

PubMed

Hoteling, Andrew J; Nichols, William F; Harmon, Patricia S; Conlon, Shawn M; Nuñez, Ivan M; Hoff, Joseph W; Cabarcos, Orlando M; Steffen, Robert B; Hook, Daniel J

2018-04-01

Polyvinylpyrrolidone (PVP) has been incorporated over the years into numerous hydrogel contact lenses as both a primary matrix component and an internal wetting agent to increase lens wettability. In this study, complementary analytical techniques were used to characterize the PVP wetting agent component of senofilcon A and samfilcon A contact lenses, both in terms of chemical composition and amount present. Photo-differential scanning calorimetry (photo-DSC), gas chromatography with a flame ionization detector (GC-FID), and high-resolution/accurate mass (HR/AM) liquid chromatography-mass spectrometry (LC-MS) techniques confirmed dual phase reaction and curing of the samfilcon A silicone hydrogel material. Gel permeation chromatography (GPC) demonstrated that high molecular weight (HMW) polymer was present in isopropanol (IPA) extracts of both lenses. High-performance liquid chromatography (HPLC) effectively separated hydrophilic PVP from the hydrophobic silicone polymers present in the extracts. Collectively, atmospheric solids analysis probe mass spectrometry (ASAP MS), Fourier transform infrared (FTIR) spectroscopy, 1 H nuclear magnetic resonance (NMR) spectroscopy, GC-FID, and LC-MS analyses of the lens extracts indicated that the majority of NVP is consumed during the second reaction phase of samfilcon A lens polymerization and exists as HMW PVP, similar to the PVP present in senofilcon A. GC-FID analysis of pyrolyzed samfilcon A and senofilcon A indicates fourfold greater PVP in samfilcon A compared with senofilcon A. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1064-1072, 2018. © 2017 Wiley Periodicals, Inc.

Rh blood phenotyping (D, E, e, C, c) microarrays using multichannel surface plasmon resonance imaging.

PubMed

Pipatpanukul, Chinnawut; Takeya, Sasaki; Baba, Akira; Amarit, Ratthasart; Somboonkaew, Armote; Sutapun, Boonsong; Kitpoka, Pimpun; Kunakorn, Mongkol; Srikhirin, Toemsak

2018-04-15

The application of Surface Plasmon Resonance Imaging (SPRi) for the detection of transmembrane antigen of the Rhesus (Rh) blood group system is demonstrated. Clinically significant Rh blood group system antigens, including D, C, E, c, and e, can be simultaneously identified via solid phase immobilization assay, which offers significant time savings and assay simplification. Red blood cells (RBCs) flowed through the micro-channel, where a suitable condition for Rh blood group detection was an RBC dilution of 1:10 with a stop-flow condition. Stop flow showed an improvement in specific binding compared to continuous flow. Rh antigens required a longer incubation time to react with the immobilized antibody than A and B antigens due to the difference in antigen type and their location on the RBC. The interaction between the immobilized antibodies and their specific antigenic counterpart on the RBC showed a significant difference in RBC removal behavior using shear flow, measured from the decay of the SPR signal. The strength of the interaction between the immobilized antibody and RBC antigen was determined from the minimum wall shear stress required to start the decay process in the SPR signal. For a given range of immobilized antibody surface densities, the Rh antigen possesses a stronger interaction than A, B, and AB antigens. Identification of 82 samples of ABO and Rh blood groups using SPRi showed good agreement with the standard micro-column agglutination technique. A wider coverage of antigenic recognition for RBC when using the solid phase immobilization assay was demonstrated for the RBC with the antigenic site located on the transmembrane protein of the clinically significant Rh antigen. Given the level of accuracy and precision, the technique showed potential for the detection of the Rh minor blood group system. Copyright © 2017 Elsevier B.V. All rights reserved.

Molecular origin of contact line stick-slip motion during droplet evaporation

PubMed Central

Wang, FengChao; Wu, HengAn

2015-01-01

Understanding and controlling the motion of the contact line is of critical importance for surface science studies as well as many industrial engineering applications. In this work, we elucidate the molecular origin of contact line stick-slip motion during the evaporation of liquid droplets on flexible nano-pillared surfaces using molecular dynamics simulations. We demonstrate that the evaporation-induced stick-slip motion of the contact line is a consequence of competition between pinning and depinning forces. Furthermore, the tangential force exerted by the pillared substrate on the contact line was observed to have a sawtooth-like oscillation. Our analysis also establishes that variations in the pinning force are accomplished through the self-adaptation of solid-liquid intermolecular distances, especially for liquid molecules sitting directly on top of the solid pillar. Consistent with our theoretical analysis, molecular dynamics simulations also show that the maximum pinning force is quantitatively related to both solid-liquid adhesion strength and liquid-vapor surface tension. These observations provide a fundamental understanding of contact line stick-slip motion on pillared substrates and also give insight into the microscopic interpretations of contact angle hysteresis, wetting transitions and dynamic spreading. PMID:26628084

Direct observation of intermediate states in model membrane fusion

PubMed Central

Keidel, Andrea; Bartsch, Tobias F.; Florin, Ernst-Ludwig

2016-01-01

We introduce a novel assay for membrane fusion of solid supported membranes on silica beads and on coverslips. Fusion of the lipid bilayers is induced by bringing an optically trapped bead in contact with the coverslip surface while observing the bead’s thermal motion with microsecond temporal and nanometer spatial resolution using a three-dimensional position detector. The probability of fusion is controlled by the membrane tension on the particle. We show that the progression of fusion can be monitored by changes in the three-dimensional position histograms of the bead and in its rate of diffusion. We were able to observe all fusion intermediates including transient fusion, formation of a stalk, hemifusion and the completion of a fusion pore. Fusion intermediates are characterized by axial but not lateral confinement of the motion of the bead and independently by the change of its rate of diffusion due to the additional drag from the stalk-like connection between the two membranes. The detailed information provided by this assay makes it ideally suited for studies of early events in pure lipid bilayer fusion or fusion assisted by fusogenic molecules. PMID:27029285

Direct observation of intermediate states in model membrane fusion.

PubMed

Keidel, Andrea; Bartsch, Tobias F; Florin, Ernst-Ludwig

2016-03-31

We introduce a novel assay for membrane fusion of solid supported membranes on silica beads and on coverslips. Fusion of the lipid bilayers is induced by bringing an optically trapped bead in contact with the coverslip surface while observing the bead's thermal motion with microsecond temporal and nanometer spatial resolution using a three-dimensional position detector. The probability of fusion is controlled by the membrane tension on the particle. We show that the progression of fusion can be monitored by changes in the three-dimensional position histograms of the bead and in its rate of diffusion. We were able to observe all fusion intermediates including transient fusion, formation of a stalk, hemifusion and the completion of a fusion pore. Fusion intermediates are characterized by axial but not lateral confinement of the motion of the bead and independently by the change of its rate of diffusion due to the additional drag from the stalk-like connection between the two membranes. The detailed information provided by this assay makes it ideally suited for studies of early events in pure lipid bilayer fusion or fusion assisted by fusogenic molecules.

Rapid classification of biological components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thompson, Vicki S.; Barrett, Karen B.; Key, Diane E.

A method is disclosed for analyzing a biological sample by antibody profiling for identifying forensic samples or for detecting the presence of an analyte. In an illustrative embodiment of the invention, the analyte is a drug, such as marijuana, Cocaine (crystalline tropane alkaloid), methamphetamine, methyltestosterone, or mesterolone. The method involves attaching antigens of the surface of a solid support in a preselected pattern to form an array wherein the locations of the antigens are known; contacting the array with the biological sample such that a portion of antibodies in the sample reacts with and binds to antigens in the array,more » thereby forming immune complexes; washing away antibodies that do not form immune complexes; and detecting the immune complexes, thereby forming an antibody profile. Forensic samples are identified by comparing a sample from an unknown source with a sample from a known source. Further, an assay, such as a test for illegal drug use, can be coupled to a test for identity such that the results of the assay can be positively correlated to a subject's identity.« less

Rapid classification of biological components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thompson, Vicki S.; Barrett, Karen B.; Key, Diane E.

A method is disclosed for analyzing a biological sample by antibody profiling for identifying forensic samples or for detecting the presence of an analyte. In an illustrative embodiment of the invention, the analyte is a drug, such as marijuana, cocaine (crystalline tropane alkaloid), methamphetamine, methyltestosterone, or mesterolone. The method involves attaching antigens to a surface of a solid support in a preselected pattern to form an array wherein the locations of the antigens are known; contacting the array with the biological sample such that a portion of antibodies in the sample reacts with and binds to antigens in the array,more » thereby forming immune complexes; washing away antibodies that do not form immune complexes; and detecting the immune complexes, thereby forming an antibody profile. Forensic samples are identified by comparing a sample from an unknown source with a sample from a known source. Further, an assay, such as a test for illegal drug use, can be coupled to a test for identity such that the results of the assay can be positively correlated to a subject's identity.« less

Antibody profiling sensitivity through increased reporter antibody layering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Apel, William A.; Thompson, Vicki S

A method for analyzing a biological sample by antibody profiling for identifying forensic samples or for detecting the presence of an analyte. In an embodiment of the invention, the analyte is a drug, such as marijuana, Cocaine (crystalline tropane alkaloid), methamphetamine, methyltestosterone, or mesterolone. The method comprises attaching antigens to a surface of a solid support in a preselected pattern to form an array wherein locations of the antigens are known; contacting the array with the biological sample such that a portion of antibodies in the sample reacts with and binds to the antigens in the array to form immunemore » complexes; washing away antibodies that do form immune complexes; and detecting the immune complexes, to form an antibody profile. Forensic samples are identified by comparing a sample from an unknown source with a sample from a known source. Further, an assay, such as a test for illegal drug use, can be coupled to a test for identity such that the results of the assay can be positively correlated to the subject's identity.« less