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Mei S Yamaguchi, Mitchell M McCartney, Angela L Linderholm, Susan E Ebeler, Michael Schivo, Cristina E Davis
The human respiratory tract releases volatile metabolites into exhaled breath that can be utilized for noninvasive health diagnostics. To understand the origin of this metabolic process, our group has previously analyzed the headspace above human epithelial cell cultures using solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). In the present work, we improve our model by employing sorbent-covered magnetic stir bars for headspace sorptive extraction (HSSE). Sorbent-coated stir bar analyte recovery increased by 52 times and captured 97 more compounds than SPME...
May 12, 2018: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
Samina Akbar, Jacob Boswell, Carys Worsley, Joanne M Elliott, Adam M Squires
In this paper, we present an attractive method for the fabrication of long, straight, highly crystalline ultra-thin platinum nanowires. The fabrication is simply achieved using an inverse hexagonal (HII) lyotropic liquid crystal phase of the commercial surfactant phytantriol as a template. A platinum precursor dissolved within the cylindrical aqueous channels of the liquid crystal phase is chemically reduced by galvanic displacement using stainless steel. We demonstrate the production of nanowires using the HII phase in the phytantriol/water system which we obtain either by heating to 55 °C, or at room temperature by the addition of a hydrophobic liquid, 9-cis-tricosene, to relieve packing frustration...
May 21, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Peilin Yang, Lu Bai, Wenqin Wang, John Rabasco
Hydrophobically modified ethylene oxide urethane (HEUR) rheology modifiers are polymers used widely in waterborne coatings and other consumer products. The incorporation of hydrophobic end-groups significantly affects the thickening performance of HEURs. Therefore, understanding the degree of incorporation of hydrophobic end-groups on the polymer chain can help gain important insights on the structure/property relationship for HEUR rheology modifiers. A comprehensive two-dimensional liquid chromatography (2D-LC) method was developed for separating polymeric HEUR rheology modifiers based on the number of hydrophobic end-groups incorporated on the polymer chain...
May 16, 2018: Journal of Chromatography. A
Reza Haghani Hassan Abadi, Abbas Fakhari, Mohammad Hassan Rahimian
In this paper, we propose a multiphase lattice Boltzmann model for numerical simulation of ternary flows at high density and viscosity ratios free from spurious velocities. The proposed scheme, which is based on the phase-field modeling, employs the Cahn-Hilliard theory to track the interfaces among three different fluid components. Several benchmarks, such as the spreading of a liquid lens, binary droplets, and head-on collision of two droplets in binary- and ternary-fluid systems, are conducted to assess the reliability and accuracy of the model...
March 2018: Physical Review. E
Muhammed Rasi M, K P Zuhail, Arun Roy, Surajit Dhara
The competing effect of surface anchoring of dispersed microparticles and elasticity of nematic and cholesteric liquid crystals has been shown to stabilize a variety of topological defects. Here we study a pair of colloidal microparticles with homeotropic and planar surface anchoring across N-SmA-SmC phase transitions. We show that below the SmA-SmC phase transition the temperature dependence of interparticle separation (D) of colloids with homeotropic anchoring shows a power-law behavior; D∼(1-T/T_{AC})^{α}, with an exponent α≈0...
March 2018: Physical Review. E
Jarrod Schiffbauer, Tengfei Luo
We investigate the nature of vapor bubble formation near a nanoscale-curved convex liquid-solid interface using two models: an equilibrium Gibbs model for homogenous nucleation, and a nonequilibrium dynamic van der Waals-diffuse-interface model for phase change in an initially cool liquid. Vapor bubble formation is shown to occur for sufficiently large radius of curvature and is suppressed for smaller radii. Solid-fluid interactions are accounted for and it is shown that liquid-vapor interfacial energy, and hence Laplace pressure, has limited influence over bubble formation...
March 2018: Physical Review. E
Hong Liang, Jiangrong Xu, Jiangxing Chen, Huili Wang, Zhenhua Chai, Baochang Shi
In this paper, we present a simple and accurate lattice Boltzmann (LB) model for immiscible two-phase flows, which is able to deal with large density contrasts. This model utilizes two LB equations, one of which is used to solve the conservative Allen-Cahn equation, and the other is adopted to solve the incompressible Navier-Stokes equations. A forcing distribution function is elaborately designed in the LB equation for the Navier-Stokes equations, which make it much simpler than the existing LB models. In addition, the proposed model can achieve superior numerical accuracy compared with previous Allen-Cahn type of LB models...
March 2018: Physical Review. E
Guillaume Dechristé, Jérôme Fehrenbach, Elena Griseti, Valérie Lobjois, Clair Poignard
BACKGROUND: Since several decades, the experiments have highlighted the analogy of fusing cell aggregates with liquid droplets. The physical macroscopic models have been derived under incompressible assumptions. The aim of this paper is to provide a 3D model of growing spheroids, which is more relevant regarding embryo cell aggregates or tumor cell spheroids. METHODS: We extend the past approach to a compressible 3D framework in order to account for the tumor spheroid growth...
May 15, 2018: Journal of Theoretical Biology
Johannes Feldmeier, Sebastian Huber, Matthias Punk
We present an exact ground state solution of a quantum dimer model introduced by Punk, Allais, and Sachdev [Quantum dimer model for the pseudogap metal, Proc. Natl. Acad. Sci. U.S.A. 112, 9552 (2015).PNASA60027-842410.1073/pnas.1512206112], which features ordinary bosonic spin-singlet dimers as well as fermionic dimers that can be viewed as bound states of spinons and holons in a hole-doped resonating valence bond liquid. Interestingly, this model captures several essential properties of the metallic pseudogap phase in high-T_{c} cuprate superconductors...
May 4, 2018: Physical Review Letters
Debarghya Sarkar, Wei Wang, Matthew Mecklenburg, Andrew J Clough, Matthew Yeung, Chenhao Ren, Qingfeng Lin, Louis Blankemeier, Shanyuan Niu, Huan Zhao, Haotian Shi, Han Wang, Stephen B Cronin, Jayakanth Ravichandran, Mitul Luhar, Rehan Kapadia
The growth of crystalline compound semiconductors on amorphous and non-epitaxial substrates is a fundamental challenge for state-of-the-art thin-film epitaxial growth techniques. Direct growth of materials on technologically relevant amorphous surfaces, such as nitrides or oxides results in nanocrystalline thin-films, or nanowire type structures, preventing growth and integration of high-performance devices and circuits on these surfaces. Here we show crystalline compound semiconductors grown directly on technologically relevant amorphous and non-epitaxial substrates in geometries compatible with standard microfabrication technology...
May 18, 2018: ACS Nano
Dotse Selali Chormey, Süleyman Bodur, Dilgeş Baskın, Merve Fırat, Sezgin Bakırdere
Switchable solvent liquid-phase microextraction was combined with gas chromatography and mass spectrometry to improve the sensitivity and accuracy for the determination of selected endocrine disruptors, pesticides and hormones. The extraction method was used to complement gas chromatography with mass spectrometry by preconcentrating analytes for trace determinations. A Box-Behnken experimental design was used to evaluate the main variables and their interaction effects, and optimum parameters were selected based on the model of experimented results...
May 17, 2018: Journal of Separation Science
Haridas Mundoor, Sungoh Park, Bohdan Senyuk, Henricus H Wensink, Ivan I Smalyukh
Order and fluidity often coexist, with examples ranging from biological membranes to liquid crystals, but the symmetry of these soft-matter systems is typically higher than that of the constituent building blocks. We dispersed micrometer-long inorganic colloidal rods in a nematic liquid crystalline fluid of molecular rods. Both types of uniaxial building blocks, while freely diffusing, interact to form an orthorhombic nematic fluid, in which like-sized rods are roughly parallel to each other and the molecular ordering direction is orthogonal to that of colloidal rods...
May 18, 2018: Science
Gokhan Zengin, Ismail Senkardes, Adriano Mollica, Carene Marie Nancy Picot-Allain, Gizem Bulut, Ahmet Dogan, M Fawzi Mahomoodally
Salvia sclarea L. is traditionally used to manage common human ailments and is consumed as a food product. This study aimed to establish the phytochemical profile and antioxidant potential of ethyl acetate, methanol, and water extracts of Salvia sclarea. The inhibitory action of the extracts against α-amylase, α-glucosidase, acetylcholinesterase, butyrylcholinesterase, and tyrosinase was also investigated. Methanol extract showed the highest phenolic and flavonoid contents (81.78 mg GAE/g extract and 40...
May 6, 2018: Computational Biology and Chemistry
Konstantin O Zamuruyev, Alexander James Schmidt, Eva Borras, Mitchell M McCartney, Michael Schivo, Nicholas J Kenyon, Jean-Pierre Delplanque, Cristina E Davis
In this work, we present a hydrophilic self-cleaning condenser surface for collection of biological and environmental aerosol samples. The condenser is installed in a battery-operated, hand-held breath sampling device. The device performance is characterized with collection and analysis of exhaled breath samples from a group of volunteers. The exhaled breath condensate is collected on a sub-cooled condenser surface, transferred into a storage vial, and its chemical content is analyzed with mass spectrometric methods...
May 17, 2018: Journal of Breath Research
Silvana Alves de Souza, Telma Maria Guedes da Silva, Eva Monica Sarmento da Silva, Celso Amorim Camara, Tania Maria Sarmento Silva
INTRODUCTION: Melipona subnitida Ducke (jandaíra) is a stingless bee native to north-eastern Brazil, which produces geopropolis, a mixture of beeswax, plant resins, pollens and earth that is used for sealing beehives. OBJECTIVE: To extend the knowledge on phenolic compounds in fractions obtained by C18-solid phase extraction (SPE) of nine geopropolis samples from Melipona subnitida collected at different times. METHODOLOGY: Chromatographic profiles of nine samples of geopropolis from jandaíra were analysed by ultra-performance liquid chromatography coupled with a diode array detector and quadrupole time-of-flight mass spectrometry (UPLC-DAD-QTOF-MS/MS) and combined with the use of data-independent acquisition (MSE) for the profiling and structural characterisation of the phenolic compounds...
May 17, 2018: Phytochemical Analysis: PCA
Yu Xia, Tyler S Mathis, Meng-Qiang Zhao, Babak Anasori, Alei Dang, Zehang Zhou, Hyesung Cho, Yury Gogotsi, Shu Yang
The scalable and sustainable manufacture of thick electrode films with high energy and power densities is critical for the large-scale storage of electrochemical energy for application in transportation and stationary electric grids. Two-dimensional nanomaterials have become the predominant choice of electrode material in the pursuit of high energy and power densities owing to their large surface-area-to-volume ratios and lack of solid-state diffusion1,2 . However, traditional electrode fabrication methods often lead to restacking of two-dimensional nanomaterials, which limits ion transport in thick films and results in systems in which the electrochemical performance is highly dependent on the thickness of the film1-4 ...
May 2018: Nature
Mami Horie, Kazuki Takahashi, Hidetaka Nanao, Masayuki Shirai
Platinum nanosheets between graphite layers were prepared by a thermal treatment of the mixture of platinum chloride (IV) and graphite powder under 0.3 MPa of chlorine at 723 K for 7 days, followed by the reduction under 40 kPa of hydrogen at 573 K for 1 h. Two-dimensional platinum metal nanosheets of 1-3 nm thickness and of 100-200 nm width were intercalated between graphite layers (Pt-GIC). The platinum nanosheets had a number of hexagonal holes and edges with angle of 120°. Liquid phase hydrogenation of cinnamaldehyde (CAL) was studied over Pt-GIC which was compared with that over platinum metal particles supported on graphite layers (Pt/Gmix)...
January 1, 2018: Journal of Nanoscience and Nanotechnology
Anamarija Knežević, Irena Dokli, Marin Sapunar, Suzana Šegota, Ute Baumeister, Andreja Lesac
The investigation of liquid crystal (LC) mixtures is of great interest in tailoring material properties for specific applications. The recent discovery of the twist-bend nematic phase (NTB ) has sparked great interest in the scientific community, not only from a fundamental viewpoint, but also due to its potential for innovative applications. Here we report on the unexpected phase behaviour of a binary mixture of twist-bend nematogens. A binary phase diagram for mixtures of imino-linked cyanobiphenyl (CBI) dimer and imino-linked benzoyloxy-benzylidene (BB) dimer shows two distinct domains...
2018: Beilstein Journal of Nanotechnology
Yuri P Panarin, Sithara P Sreenilayam, Jagdish K Vij, Anne Lehmann, Carsten Tschierske
Two homologue achiral bent-core liquid crystals (LCs), BCN66 and BCN84, in their nematic phases are studied by dielectric spectroscopy in the frequency range 10 Hz-10 MHz. In each of these compounds, two relaxation processes are identified and assigned to (i) collective dynamics of molecules in nanometer-sized cybotactic clusters and (ii) individual molecular relaxations, in the ascending order of frequency of the probe field. The temperature and the bias electric field dependence of the dielectric strength and relaxation frequency for these processes are shown to give rise to sharpness in cluster boundaries, increased size and volume fraction in the LC nematic phase...
2018: Beilstein Journal of Nanotechnology
Isla Zhang, Rattachai Pinchaipat, Nigel B Wilding, Malcolm A Faers, Paul Bartlett, Robert Evans, C Patrick Royall
Understanding the phase behaviour of mixtures continues to pose challenges, even for systems that might be considered "simple." Here, we consider a very simple mixture of two colloidal and one non-adsorbing polymer species, which can be simplified even further to a size-asymmetrical binary mixture, in which the effective colloid-colloid interactions depend on the polymer concentration. We show that this basic system exhibits surprisingly rich phase behaviour. In particular, we enquire whether such a system features only a liquid-vapor phase separation (as in one-component colloid-polymer mixtures) or whether, additionally, liquid-liquid demixing of two colloidal phases can occur...
May 14, 2018: Journal of Chemical Physics
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