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https://www.readbyqxmd.com/read/28738646/synthesis-characterization-and-application-of-a-novel-multifunctional-stationary-phase-for-hydrophilic-interaction-reversed-phase-mixed-mode-chromatography
#1
Hayriye Aral, K Serdar Çelik, Ramazan Altındağ, Tarık Aral
A novel multifunctional stationary phase based on silica gel was synthesised starting from L- isoleucine and 4-phenylbutylamine and evaluated as a hydrophilic interaction/reversed-phase mixed-mode stationary phase for high-performance liquid chromatography (HPLC). The prepared stationary phase was characterized by elemental analysis, infrared spectroscopy (IR), scanning electron microscopy (SEM), Brunauer, Emmett and Teller (BET) and solid-state (13)C nuclear magnetic resonance (NMR). The mechanisms involved in the chromatographic separation are multi-interaction, including hydrophobic, π-π, hydrogen-bonding, dipole-dipole and ion-dipole interactions...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738645/competitive-fluorescence-anisotropy-polarization-assay-for-atp-using-aptamer-as-affinity-ligand-and-dye-labeled-atp-as-fluorescence-tracer
#2
Yapiao Li, Linlin Sun, Qiang Zhao
We developed an aptamer-based competitive fluorescence anisotropy (FA)/fluorescence polarization (FP) assay for adenosine triphosphate (ATP). Different from the traditional fluorescence polarization immunoassays for small molecules, here DNA aptamer against ATP was used as affinity ligand, and tetramethylrhodamine (TMR) labeled ATP served as fluorescent tracer. The binding between TMR-labeled ATP and aptamer gave large FA due to molecular volume increase and restricted rotation of the dye-labeled ATP. When ATP was added in solution, ATP competitively displaced the TMR-labeled ATP from aptamer affinity complex, causing decrease of FA of TMR-labeled ATP...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738625/the-screening-of-organic-matter-in-mineral-and-tap-water-by-uhplc-hrms
#3
Marcos A S Ribeiro, Michael Murgu, Valquíria de Moraes Silva, Alexandra C H F Sawaya, Leomara Floriano Ribeiro, Andre Justi, Eduardo C Meurer
It is highly desirable to screen for a large variety of organic compounds in water. Ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS) can analyse semi-polar to polar organic compounds in tap and mineral water. The use of UHPLC-HRMS is well consolidated for lipidomic, metabolomic and proteomic studies; based on the detection of a very large number of compounds of a variety of organic functions. Water analysis is usually performed by gas chromatography -mass spectrometry (GC-MS) techniques that are efficient for volatile organic compounds...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738623/analysis-of-illegal-peptide-drugs-via-hilic-dad-ms
#4
Steven Janvier, Evelien De Sutter, Evelien Wynendaele, Bart De Spiegeleer, Celine Vanhee, Eric Deconinck
Biopharmaceuticals have established themselves as highly efficient medicines, and are still one of the fastest growing parts of the health-product industry. Unfortunately, the introduction of these promising new drugs went hand in hand with the creation of a black market for illegal and counterfeit biotechnology drugs. Particularly popular are the lyophilised peptides with a molecular weight of less than 5kDa. Most of them are meant for subcutaneous injection and are easily accessible via the internet. In recent years, different methods based on reversed phase liquid chromatography have been developed to detect and quantify these peptides...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738566/preparation-and-evaluation-of-a-novel-n-benzyl-phenethylamino-%C3%AE-cyclodextrin-bonded-chiral-stationary-phase-for-hplc
#5
Liang Li, Biaoping Cheng, Rendan Zhou, Zhigang Cao, Chun Zeng, Laisheng Li
A novel N-benzyl-phenethylamino-β-cyclodextrin-bonded ordered mesoporous SBA-15 chiral stationary phase (BZCDP) for high-performance liquid chromatography (HPLC) was prepared. The structure and morphology of the ligand and the stationary phase were characterized by mass spectrometry, elemental analysis, infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and thermogravimetric analysis. The enantiomers of chiral compounds including nine common β-adrenergic blocker drugs (β-blockers), eight dansyl amino acids (DNS-AA) and six flavanones were successfully separated by polar organic solvent and reversed-phase chromatography, respectively...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738556/development-of-a-new-sample-preparation-method-based-on-liquid-liquid-liquid-extraction-combined-with-dispersive-liquid-liquid-microextraction-and-its-application-on-unfiltered-samples-containing-high-content-of-solids
#6
Mir Ali Farajzadeh, Maryam Abbaspour
A new sample preparation method based on liquid-liquid-liquid extraction combined with dispersive liquid-liquid microextraction followed by gas chromatography-flame ionization detection has been reported for the extraction/preconcentration and determination of trace levels of twelve pesticide residues from different samples with high content of solids without filtration. This method consists of a three-phase system including an aqueous phase (sample solution), acetonitrile, and hexane. The extraction mechanism is based on different affinities of the substances from the sample matrices towards each of the involved phase, which provides a high selectivity to the process...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738264/evidence-of-anomalous-behavior-of-intermolecular-interactions-at-low-concentration-of-methanol-in-ethanol-methanol-binary-system
#7
K Nilavarasi, Thejus R Kartha, V Madhurima
At low concentrations of methanol in a binary system of ethanol and methanol, uniquely complex molecular interactions are reported here. Previous studies indicate that ethanol molecules form aggregates held together by hydrogen bonding (O-H-O) and also dispersive forces. Addition of small amount of methanol tends to break the hydrogen bond network of ethanol due to the larger polarity of methanol. This leads to the ethanol molecules becoming somewhat isolated from each other within a scaffolding network of methanol molecules, as seen from the present molecular dynamics simulations...
July 15, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28738197/tracking-changes-in-composition-and-amount-of-dissolved-organic-matter-throughout-drinking-water-treatment-plants-by-comprehensive-two-dimensional-gas-chromatography-quadrupole-mass-spectrometry
#8
Chunmei Li, Donghong Wang, Xiong Xu, Meijia Xu, Zijian Wang, Ruiyang Xiao
Dissolved organic matter (DOM) can affect the performance of water treatment processes and produce undesirable disinfection by-products during disinfection. Several studies have been undertaken on the structural characterization of DOM, but its fate during drinking water treatment processes is still not fully understood. In this work, the nontargeted screening method of comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC×GC-qMS) was used to reveal the detailed changes of different chemical classes of compounds in DOM during conventional and advanced drinking water treatment processes at three drinking water treatment plants in China...
July 21, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28737898/systematic-thermodynamics-of-layered-perovskites-ruddlesden-popper-phases
#9
Leslie Glasser
Perovskite, CaTiO3, is the prototype of an extensive group of materials. They are capable of considerable chemical modification, with the further capability of undergoing structural modification by the intercalation of thin sheets of intrusive materials (both inorganic and organic) between the cubic perovskite layers, to form a range of "layered" perovskites. These changes bring about alterations in their electronic, structural, and other properties, permitting some "tuning" toward specific ends. This paper collects the limited known thermodynamic data for layered perovskites of various chemical compositions and demonstrates by example that the thermodynamic layer values are substantially additive...
July 24, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28737792/ferromagnetic-resonance-of-nicofe2o4-nanoparticles-and-microwave-absorption-properties-of-flexible-nicofe2o4-carbon-black-poly-vinyl-alcohol-composites
#10
Gopal Datt, Chetan Kotabage, A C Abhyankar
The effect of cationic disorder and particle morphology on the ferromagnetic resonance (FMR) of NiCoFe2O4 nanoparticles (NPs) and the electromagnetic shielding effectiveness of flexible composites (wherein the nanoparticles are used as fillers) has been presented. Upon annealing at 1000 °C, spherical, ∼25 nm, single crystalline (as-prepared) NPs are transformed into octahedral, ∼200 nm, polycrystalline (annealed) NPs and change the cationic distribution significantly. The effect of shape, size and cationic distribution on the resonance properties has been discussed using the randomly-oriented anisotropic-axis model...
July 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28737790/tuning-the-gap-of-lead-based-halide-perovskites-by-introducing-superalkali-species-at-the-cationic-sites-of-abx3-type-structure
#11
C Paduani, Andrew M Rappe
We study with scalar relativistic density functional theory (DFT) calculations the effect of changes in the ionicity of the bonding mechanism and charge donation on the structure and electronic properties of new lead halide perovskites which show promising performance in optoelectronic applications as long-wave infrared detectors and thermoelectrics. Our results provide evidence that the band gap of these compounds can be tuned upon the introduction of appropriate superalkali moieties at the cationic A-sites in the CsPbI3-type structure...
July 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28737779/the-nature-of-intermolecular-interactions-in-pyridinium-anion-%C3%AE-hexachlorocyclohexane-molecular-crystals
#12
I G Grosu, M I Rednic, M Miclăuş, I Grosu, A Bende
The nature of intermolecular interactions in different molecular crystal configurations formed by pyridinium cations, chloride or bromide anions as well as β-hexachlorocyclohexane (β-HCH) molecules has been investigated using high level ab initio quantum chemistry methods. Several molecular subsystems taken from the crystal unit cell were considered and their supramolecular energy stability was analyzed in detail using high level density-fitting local electron correlation (DF-LMP2 and DF-LCCSD(T)) methods together with the aug-cc-pVTZ basis set...
July 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28737772/cortical-forces-and-cdc-42-control-clustering-of-par%C3%A2-proteins-for-caenorhabditis-elegans-embryonic%C3%A2-polarization
#13
Shyi-Chyi Wang, Tricia Yu Feng Low, Yukako Nishimura, Laurent Gole, Weimiao Yu, Fumio Motegi
Cell polarization enables zygotes to acquire spatial asymmetry, which in turn patterns cellular and tissue axes during development. Local modification in the actomyosin cytoskeleton mediates spatial segregation of partitioning-defective (PAR) proteins at the cortex, but how mechanical changes in the cytoskeleton are transmitted to PAR proteins remains elusive. Here we uncover a role of actomyosin contractility in the remodelling of PAR proteins through cortical clustering. During embryonic polarization in Caenorhabditis elegans, actomyosin contractility and the resultant cortical tension stimulate clustering of PAR-3 at the cortex...
July 24, 2017: Nature Cell Biology
https://www.readbyqxmd.com/read/28737704/toxicity-at-the-edge-of-life-a-review-on-cyanobacterial-toxins-from-extreme-environments
#14
REVIEW
Samuel Cirés, María Cristina Casero, Antonio Quesada
Cyanotoxins are secondary metabolites produced by cyanobacteria, of varied chemical nature and toxic effects. Although cyanobacteria thrive in all kinds of ecosystems on Earth even under very harsh conditions, current knowledge on cyanotoxin distribution is almost restricted to freshwaters from temperate latitudes. In this review, we bring to the forefront the presence of cyanotoxins in extreme environments. Cyanotoxins have been reported especially in polar deserts (both from the Arctic and Antarctica) and alkaline lakes, but also in hot deserts, hypersaline environments, and hot springs...
July 24, 2017: Marine Drugs
https://www.readbyqxmd.com/read/28737686/comparison-of-two-stationary-phases-for-the-determination-of-phytosterols-and-tocopherols-in-mango-and-its-by-products-by-gc-qtof-ms
#15
Ana López-Cobo, Beatriz Martín-García, Antonio Segura-Carretero, Alberto Fernández-Gutiérrez, Ana María Gómez-Caravaca
Two different gas chromatography coupled to quadrupole-time of flight mass spectrometry (GC-QTOF-MS) methodologies were carried out for the analysis of phytosterols and tocopherols in the flesh of three mango cultivars and their by-products (pulp, peel, and seed). To that end, a non-polar column ((5%-phenyl)-methylpolysiloxane (HP-5ms)) and a mid-polar column (crossbond trifluoropropylmethyl polysiloxane (RTX-200MS)) were used. The analysis time for RTX-200MS was much lower than the one obtained with HP-5ms...
July 22, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28737501/synthesis-and-enhanced-microwave-absorption-properties-a-strongly-hydrogenated-tio2-nanomaterial
#16
Jianle Xu, Xiaosi Qi, Chengzhi Luo, Jie Qiao, Ren Xie, Yuan Sun, Wei Zhong, Qiang Fu, Chunxu Pan
Due to its improved physical and chemical performances, a strongly hydrogenated TiO2 was designed and produced successfully by using a sealing-transfer reduction method at a relatively low temperature (425oC). The microstructures, electromagnetic and microwave absorbing properties were investigated in details. Experimental results revealed that: 1) The minimum reflection loss (RL) value of the hydrogenated TiO2 up to -53.8 dB (99.99999 % of EM wave attenuation) was reached at 11.2 GHz, and the RL values below -20 dB (99 %) were obtained in a frequency range of 7...
July 24, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28737406/preclinical-effect-of-absorption-modifying-excipients-on-rat-intestinal-transport-of-five-model-compounds-and-the-intestinal-barrier-marker-51-cr-edta
#17
David Dahlgren, Carl Roos, Anders Lundqvist, Peter Langguth, Christer Tannergren, Markus Sjöblom, E Sjögren, H Lennernas
There is a renewed interest from the pharmaceutical field to develop oral formulations of compounds such as peptides, oligonucleotides, and polar drugs. However, these often suffer from insufficient absorption across the intestinal mucosal barrier. One approach to circumvent this problem is the use of absorption modifying excipient(s) (AME). This study determined the absorption enhancing effect of four AMEs (sodium dodecyl sulfate, caprate, chitosan, N-acetylcysteine) on five model compounds in a rat jejunal perfusion model...
July 24, 2017: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/28737254/1d-and-2d-nmr-spectroscopy-of-bonding-interactions-within-stable-and-phase-separating-organic-electrolyte-cellulose-solutions
#18
Matthew T Clough, Christophe Fares, Roberto Rinaldi
Organic electrolyte solutions (mixtures containing an ionic liquid and a polar, molecular co-solvent) are highly versatile solvents for cellu-lose. However, the underlying solvent-solvent and solvent-solute interactions are not yet fully understood. Herein, mixtures of the ionic liquid 1-ethyl-3-methylimidazolium acetate, the co-solvent 1,3-dimethyl-2-imidazolidinone, and cellulose are investigated using 1D and 2D NMR spectroscopy. The use of a triply-13C-labelled ionic liq-uid enhances the signal-to-noise ratio for 13C NMR spectroscopy, enabling changes in bonding interactions to be accurately pinpoint-ed...
July 24, 2017: ChemSusChem
https://www.readbyqxmd.com/read/28737178/electrokinetics-and-behavior-near-the-interface-of-colloidal-particles-in-non-polar-dispersions
#19
Manoj Prasad, Filip Strubbe, Filip Beunis, Kristiaan Neyts
The electrokinetics and charging of nonpolar colloidal dispersions subjected to a voltage are investigated by electric current and optical measurements. From electric current measurements in response to an alternating triangular voltage with a peak value of a few hundred volts, we find that polystyrene toner particles are compacted near the electrodes and their charge increases by more than a factor of 20. The important increase of charge is interpreted by a mechanism in which counter charges, which are originally at the particle surface, are desorbed...
July 24, 2017: Soft Matter
https://www.readbyqxmd.com/read/28737168/distribution-of-high-dimensional-entanglement-via-an-intra-city-free-space-link
#20
Fabian Steinlechner, Sebastian Ecker, Matthias Fink, Bo Liu, Jessica Bavaresco, Marcus Huber, Thomas Scheidl, Rupert Ursin
Quantum entanglement is a fundamental resource in quantum information processing and its distribution between distant parties is a key challenge in quantum communications. Increasing the dimensionality of entanglement has been shown to improve robustness and channel capacities in secure quantum communications. Here we report on the distribution of genuine high-dimensional entanglement via a 1.2-km-long free-space link across Vienna. We exploit hyperentanglement, that is, simultaneous entanglement in polarization and energy-time bases, to encode quantum information, and observe high-visibility interference for successive correlation measurements in each degree of freedom...
July 24, 2017: Nature Communications
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