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https://www.readbyqxmd.com/read/28544207/application-of-linear-gradient-elution-in-countercurrent-chromatography-for-the-separation-of-triterpenoid-saponins-from-the-roots-of-pulsatilla-koreana-nakai
#1
Kyoung Jin Lee, Kwangho Song, Da Young Song, Yeong Shik Kim
A linear gradient elution method using countercurrent chromatography was developed for the separation of four triterpenoid saponins from the roots of Pulsatilla koreana Nakai, including hederacolchiside E, which is responsible for the neuroprotective activity of this plant. The target fraction was obtained by 80% methanol elution of solid phase column chromatography. The partition coefficients of the target compounds were very different, which means they are difficult to separate with a single biphasic solvent system...
May 19, 2017: Journal of Separation Science
https://www.readbyqxmd.com/read/28543517/intermediate-and-advanced-topics-in-multilevel-logistic-regression-analysis
#2
Peter C Austin, Juan Merlo
Multilevel data occur frequently in health services, population and public health, and epidemiologic research. In such research, binary outcomes are common. Multilevel logistic regression models allow one to account for the clustering of subjects within clusters of higher-level units when estimating the effect of subject and cluster characteristics on subject outcomes. A search of the PubMed database demonstrated that the use of multilevel or hierarchical regression models is increasing rapidly. However, our impression is that many analysts simply use multilevel regression models to account for the nuisance of within-cluster homogeneity that is induced by clustering...
May 23, 2017: Statistics in Medicine
https://www.readbyqxmd.com/read/28538680/diazonium-salt-based-surface-enhanced-raman-spectroscopy-nanosensor-detection-and-quantitation-of-aromatic-hydrocarbons-in-water-samples
#3
Inga Tijunelyte, Stéphanie Betelu, Jonathan Moreau, Ioannis Ignatiadis, Catherine Berho, Nathalie Lidgi-Guigui, Erwann Guénin, Catalina David, Sébastien Vergnole, Emmanuel Rinnert, Marc Lamy de la Chapelle
Here, we present a surface-enhanced Raman spectroscopy (SERS) nanosensor for environmental pollutants detection. This study was conducted on three polycyclic aromatic hydrocarbons (PAHs): benzo[a]pyrene (BaP), fluoranthene (FL), and naphthalene (NAP). SERS substrates were chemically functionalized using 4-dodecyl benzenediazonium-tetrafluoroborate and SERS analyses were conducted to detect the pollutants alone and in mixtures. Compounds were first measured in water-methanol (9:1 volume ratio) samples. Investigation on solutions containing concentrations ranging from 10(-6) g L(-1) to 10(-3) g L(-1) provided data to plot calibration curves and to determine the performance of the sensor...
May 24, 2017: Sensors
https://www.readbyqxmd.com/read/28538521/examination-of-the-validity-of-the-atlas-informed-approach-to-functional-parcellation-a-resting-functional-mri-study
#4
Tien-Wen Lee, Shao-Wei Xue
With the advancement in MRI, functional parcellation (FP) of brain structure(s) has become an important topic. However, the large number of voxels is a major obstacle. A-priori partitioning of the brain into several regions of interest (ROIs) is the main data-reduction strategy to simplify brain informatics. This study aims to examine the validity of ROI-based approach to FP by exploring the concordance of the relative distance structures between voxel-wise (raw data) and atlas-informed analyses. Structural and resting state functional MRI (rfMRI) scans of 26 right-handed healthy individuals were selected from the Rockland dataset...
May 19, 2017: Neuroreport
https://www.readbyqxmd.com/read/28536592/trait-associations-in-diversity-panels-of-the-two-common-bean-phaseolus-vulgaris-l-gene-pools-grown-under-well-watered-and-water-stress-conditions
#5
Asrat Asfaw, Daniel Ambachew, Trushar Shah, Matthew W Blair
Common beans are a warm-season, food legume cultivated in areas prone to water limitation throughout their growing season. This study assessed the magnitude and pattern of trait associations for a total of 202 common bean genotypes divided into panels of 81 Andean and 121 Mesoamerican gene pool accessions grown under contrasting treatments of well-watered, non-stress, and water-limited, terminal drought-stress conditions. Linear correlation, complex path coefficient, and genetic divergence analyses were used to dissect the relationship dynamics between traits and the relative contribution of adaptive traits to differentiation among gene pools and genotypes based on drought stress...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28535055/ionic-liquid-anion-controlled-nanoscale-gold-morphology-grown-at-a-liquid-interface
#6
Nakara Bhawawet, Jeremy B Essner, Durgesh Vinod Wagle, Gary A Baker
Two different ionic liquids comprising the tetrabutylphosphonium cation ([P4444]) paired with the strongly-coordinating anions 6-aminocaproate ([6-AC]) or taurinate ([tau]) were prepared and employed in an aqueous/organic liquid bilayer system to generate nanoscale gold by Au(OH)4- photoreduction. Generally, as the concentration of ionic liquid in the organic phase was increased, the resulting quasi-spherical gold nanoparticles reduced in size and presented less aggregation, leading to marked increases in the catalytic efficiency for 4-nitrophenol reduction using borohydride...
May 23, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28534622/solute-partitioning-in-micelles-combining-molecular-dynamics-simulations-cosmomic-and-experiments
#7
Denitsa Yordanova, Eric Ritter, Thomas Gerlach, Jan-Hendrik Jensen, Irina Smirnova, Sven Jakobtorweihen
The partition equilibria of solutes between micelles and an aqueous phase is a key factor in many applications. Depending on the task, many micelle-solute combinations are possible. Therefore, theoretical methods to predict the partition behavior in micellar systems are needed. Here, two predictive methods are evaluated and compared. First, it is shown how molecular dynamics simulations (MD) with the umbrella sampling method can be used to calculate free energy profiles in micellar systems. The second applied method is an extension of the COSMO-RS theory to anisotropic systems termed COSMOmic...
May 23, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28522410/a-global-human-health-risk-assessment-for-octamethylcyclotetrasiloxane-d4
#8
Robinan Gentry, Allison Franzen, Cynthia Van Landingham, Tracy Greene, Kathy Plotzke
Octamethylcyclotetrasiloxane (D4) is a low-molecular-weight volatile cyclic siloxane, primarily used as an intermediate in the production of some widely-used industrial and consumer silicone based polymers and may be present as a component in a variety of consumer products. A global "harmonized" risk assessment was conducted to meet requirements for substance-specific risk assessments conducted by regulatory agencies such as USEPA's Integrated Risk Information System (IRIS), Health Canada's Chemical Management Program (CMP) and various independent scientific committees of the European Commission (e...
May 15, 2017: Toxicology Letters
https://www.readbyqxmd.com/read/28515006/two-dimensional-multi-heart-cutting-centrifugal-partition-chromatography-liquid-chromatography-for-the-preparative-isolation-of-antioxidants-from-edelweiss-plant
#9
Léa Marlot, Magali Batteau, Marie-Claire Escofet, Sylvie Nuccio, Véronique Coquoin, René De Vaumas, Karine Faure
The Edelweiss plant has been recognized as a very valuable source of anti-aging principles due to its composition of antioxidants compounds: leontopodic acid A and 3,5-dicaffeoylquinic acid. In this work, off-line multi-heart cutting CPC-LC separation was set up at industrial scale in order to isolate and produce new high quality reference material of these two antioxidants from Edelweiss. For this purpose, CPC and HPLC methods were developed and optimized at laboratory scale and a comprehensive CPCxHPLC analysis of the crude extract was established...
April 27, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28505444/explicit-incorporation-of-hard-and-soft-protein-protein-interactions-into-models-for-crowding-effects-in-protein-mixtures-2-effects-of-varying-hard-and-soft-interactions-upon-prototypical-chemical-equilibria
#10
Allen P Minton
Previously derived approximate analytical relations for the activity coefficient of each solute in a mixture of up to three spherical solutes in a highly nonideal solution interacting via square well potentials of mean force (Hoppe, T.; Minton, A. P. J Phys Chem B. 2016, 120, 11866-11872) were used to explore the effect of heterogeneity in volume occupancy and intermolecular interactions upon prototypical schemes representing solubility, partitioning, conformational isomerization, and self-association in crowded solutions...
May 25, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28502117/passive-membrane-penetration-of-the-serotonin-precursor-5-hydroxytryptophan-is-controlled-by-its-zwitterion
#11
Károly Mazák, Béla Noszál
Species-specific partition coefficients in the octanol/water system were determined for the neurotransmitter serotonin (5-HT) and its precursor 5-hydroxytryptophan (5-HTP). The pH-independent partition coefficients (p) of the individual microspecies were determined by combination of experimentally measured distribution constants and a custom-tailored evaluation method, using highly similar auxiliary compounds. Experimental microscopic partition coefficients for triprotic molecules have only been reported before for thyroxine and its derivatives...
May 14, 2017: Chemistry & Biodiversity
https://www.readbyqxmd.com/read/28501162/solidification-of-floating-organic-droplet-in-dispersive-liquid-liquid-microextraction-as-a-green-analytical-tool
#12
REVIEW
Fotouh R Mansour, Neil D Danielson
Dispersive liquid-liquid microextraction (DLLME) is a special type of microextraction in which a mixture of two solvents (an extracting solvent and a disperser) is injected into the sample. The extraction solvent is then dispersed as fine droplets in the cloudy sample through manual or mechanical agitation. Hence, the sample is centrifuged to break the formed emulsion and the extracting solvent is manually separated. The organic solvents commonly used in DLLME are halogenated hydrocarbons that are highly toxic...
August 1, 2017: Talanta
https://www.readbyqxmd.com/read/28500972/fate-and-transport-of-hexahydro-1-3-5-trinitro-1-3-5-triazine-rdx-and-its-degradation-products-in-sedimentary-and-volcanic-rocks-los-alamos-new-mexico
#13
Brent Porter Heerspink, Sachin Pandey, Hakim Boukhalfa, Doug S Ware, Oana Marina, George Perkins, Velimir V Vesselinov, Giday WoldeGabriel
High-explosive compounds including hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) were used extensively in weapons research and testing at Los Alamos National Laboratory (LANL). Liquid effluents containing RDX were released to an outfall pond that flowed to Cañon de Valle at LANL's Technical Area 16 (TA-16), resulting in the contamination of the alluvial, intermediate and regional groundwater bodies. Monitoring of groundwater within Cañon de Valle has shown persistent RDX in the intermediate perched zone located between 225 and 311 m below ground surface...
May 2, 2017: Chemosphere
https://www.readbyqxmd.com/read/28497526/prevention-removal-and-inactivation-of-escherichia-coli-and-staphylococcus-aureus-biofilms-using-selected-monoterpenes-of-essential-oils
#14
A Borges, J C Lopez-Romero, D Oliveira, E Giaouris, M Simões
AIMS: The aim of this study was to investigate the antibiofilm potential of five essential oils (EOs) components with cyclic (sabinene-SAB, carveol-C1, carvone-C2) and acyclic (citronellol-C3 and citronellal-C4) structures against Escherichia coli and Staphylococcus aureus. METHODS AND RESULTS: The selected EOs components prevented biofilm set-up, with C3 and C4 causing remarkable effects. When applied against pre-established biofilms, they promoted high biomass removal and inactivation of biofilm cells...
May 12, 2017: Journal of Applied Microbiology
https://www.readbyqxmd.com/read/28494350/liquid-chromatography-tandem-mass-spectrometry-quantification-of-acetamiprid-and-thiacloprid-residues-in-butterbur-grown-under-regulated-conditions
#15
Han Sol Lee, Sung-Woo Kim, A M Abd El-Aty, Hyung Suk Chung, Md Humayun Kabir, Md Musfiqur Rahman, Ji Hoon Jeong, Byung-Joon Chang, Ho-Chul Shin, Jae-Han Shim
An analytical method was developed to quantify the residual levels of the neonicotinoid insecticides, acetamiprid and thiacloprid, in field-incurred butterbur samples using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Samples were extracted with acetonitrile and partitioned with dichloromethane. After partitioning, purification was conducted using a Florisil(®) cartridge. Linearity of a matrix-matched calibration curve of the two compounds over a concentration range of 0.004-0.4μg/g was excellent, with determination coefficients (R(2))≥0...
April 13, 2017: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
https://www.readbyqxmd.com/read/28492487/application-of-soluplus-to-improve-the-flowability-and-dissolution-of-baicalein-phospholipid-complex
#16
Junting Fan, Yunhao Dai, Hongxue Shen, Jianming Ju, Zhiying Zhao
In this study, a novel ternary complex system (TCS) composed of baicalein, phospholipids, and Soluplus was prepared to improve the flowability and dissolution for baicalein phospholipid complex (BPC). TCS was characterized using differential scanning calorimetry (DSC), infrared spectroscopy (IR), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). The flowability, solubility, oil-water partition coefficient, in vitro dissolution, and in vivo pharmacokinetics of the system were also evaluated...
May 11, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28489342/ph-sensitive-reversible-programmed-targeting-strategy-by-the-self-assembly-disassembly-of-gold-nanoparticles
#17
Jinlong Ma, Zhenpeng Hu, Wei Wang, Xinyu Wang, Qiang Wu, Zhi Yuan
A reversible programmed targeting strategy could achieve high tumor accumulation due to its long blood circulation time and high cellular internalization. Here, targeting ligand-modified poly(ethylene glycol) (PEG-ligand), dibutylamines (Bu), and pyrrolidinamines (Py) were introduced on the surface of gold nanoparticles (Au NPs) for reversible shielding/deshielding of the targeting ligands by pH-responsive self-assembly. Hydrophobic interaction and steric repulsion are the main driving forces for the self-assembly/disassembly of Au NPs...
May 10, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28488933/zebrafish-as-a-screening-model-for-testing-the-permeability-of-blood-brain-barrier-to-small-molecules
#18
Seong Soon Kim, So Hee Im, Jung Yoon Yang, Yu-Ri Lee, Geum Ran Kim, Jin Sil Chae, Dae-Seop Shin, Jin Sook Song, Sunjoo Ahn, Byung Hoi Lee, Jae Chun Woo, Jin Hee Ahn, Chang Soo Yun, Phiho Kim, Hyoung Rae Kim, Kyeong-Ryoon Lee, Myung Ae Bae
The objective of this study was to evaluate the permeability of small molecules into the brain via the blood-brain barrier in zebrafish and to investigate the possibility of using this animal model as a screening tool during the early stages of drug discovery. Fifteen compounds were used to understand the permeation into the brain in zebrafish and mice. The ratio of brain-to-plasma concentration was compared between the two animal models. The partition coefficient (Kp,brain), estimated using the concentration ratio at designated times (0...
May 10, 2017: Zebrafish
https://www.readbyqxmd.com/read/28482513/modeling-the-permeability-of-multiaxial-electrospun-poly-%C3%AE%C2%B5-caprolactone-gelatin-hybrid-fibers-for-controlled-doxycycline-release
#19
Abdurizzagh Khalf, Sundararajan V Madihally
Recent advances in electrospinning allow the formation of multiple layers of micro and nanosize fibers to regulate drug/therapeutic agent release. Although there has been significant progress in fiber formation techniques and drug loading, fundamental models providing insights into controlling individual permeabilities is lacking. In this regard, we first explored forming coaxial hybrid fibers from hydrophobic poly(ε-caprolactone) (PCL) and hydrophilic gelatin (GT) in three different configurations, and the release of hydrophilic doxycycline (Dox) at 37°C over five days...
July 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28479726/anti-plasmodial-and-chloroquine-resistance-suppressive-effects-of-embelin
#20
O I Zaid, R Abd Majid, M S Hasidah, M N Sabariah, K Al-Zihiry, Sattar Rahi, R Basir
BACKGROUND: Emergence of chloroquine (CQ) resistance among different strains of Plasmodium falciparum is the worst catastrophe that has ever perplexed the dedicated efforts to eradicate malaria. This urged the scientists to search for new alternatives or sensitizers to augment its antiplasmodium effect. MATERIALS AND METHOD: In this experiment, the potential of embelin, isolated from Embelia ribes, to inhibit the growth and sensitize CQ action was screened using SYBRE-green-I based drug sensitivity and isobologram assays, respectively...
January 2017: Pharmacognosy Magazine
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