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https://www.readbyqxmd.com/read/28817770/photoinduced-copper-catalyzed-alkylation-of-amines-a-mechanistic-study-of-the-cross-coupling-of-carbazole-with-alkyl-bromides
#1
Jun Myun Ahn, Tanvi S Ratani, Kareem Hannoun, Gregory C Fu, Jonas C Peters
We have recently reported that a variety of couplings of nitrogen, sulfur, oxygen, and carbon nucleophiles with organic halides can be achieved under mild conditions (-40 to 30 °C) through the use of light and a copper catalyst. Insight into the various mechanisms by which these reactions proceed may enhance our understanding of chemical reactivity and facilitate the development of new methods. In this report, we apply an array of tools (EPR, NMR, transient absorption, and UV-vis spectroscopy; ESI-MS; X-ray crystallography; DFT calculations; reactivity, stereochemical, and product studies) to investigate the photoinduced, copper-catalyzed coupling of carbazole with alkyl bromides...
August 17, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28817729/comparison-of-bioimpedance-spectroscopy-and-x-ray-micro-computed-tomography-for-total-fat-volume-measurement-in-mice
#2
Gaelle Aubertin, Amira Sayeh, Jean-Philippe Dillenseger, Estelle Ayme-Dietrich, Philippe Choquet, Nathalie Niederhoffer
Obesity and the metabolic syndrome are two pathologies whose prevalence are in a constant increase. Evaluation of the total fat mass but also of the distribution between visceral and subcutaneous adipose tissue are important factors while assessing the pathophysiology of these two pathologies. Computed tomography (CT) and bioimpedance (BIS) are the translational methods the most frequently used in human beings as well as in rodent models in longitudinal studies on adiposity and obesity. Surprisingly, no direct comparison of micro-CT and BIS was reported yet in mice...
2017: PloS One
https://www.readbyqxmd.com/read/28817614/development-of-a-technique-for-psyllium-husk-mucilage-purification-with-simultaneous-microencapsulation-of-curcumin
#3
André Álvares Monge Neto, Rita de Cássia Bergamasco, Flávio Faria de Moraes, Antônio Medina Neto, Rosane Marina Peralta
This study focused on evaluating a technique for the psyllium husk mucilage (PHM) purification with simultaneous microencapsulation of curcumin. PHM was extracted with water and purified with ethanol. For the mucilage purification and simultaneous microencapsulation, an ethanolic solution of curcumin was used. After dehydration, the samples were analysed by instrumental techniques and evaluated for thermal stability. The presence of curcumin in the solution did not impair the yield of precipitated polysaccharide...
2017: PloS One
https://www.readbyqxmd.com/read/28817312/disulfide-mapping-planner-software-tool
#4
Andreas M Kist, Angelika Lampert, Andrias O O'Reilly
Disulfide bridges are side-chain-mediated covalent bonds between cysteines that stabilize many protein structures. Disulfide mapping experiments to resolve these linkages typically involve proteolytic cleavage of the protein of interest followed by mass spectroscopy to identify fragments corresponding to linked peptides. Here we report the sequence-based "DIMPL" web tool to facilitate the planning and analysis steps of experimental mapping studies. The software tests permutations of user-selected proteases to determine an optimal peptic digest that produces cleavage between cysteine residues, thus separating each to an individual peptide fragment...
August 17, 2017: Journal of Computational Biology: a Journal of Computational Molecular Cell Biology
https://www.readbyqxmd.com/read/28817280/x-ray-spectroscopy-uncovering-the-effects-of-cu-based-nanoparticle-concentration-and-structure-on-phaseolus-vulgaris-germination-and-seedling-development
#5
Nádia Marion Duran, Susilaine Maira Savassa, Rafael G Lima, Eduardo de Almeida, Francisco Scaglia Linhares, Cornelis A M van Gestel, Hudson W Pereira de Carvalho
Presenting fertilizers in nano form can improve their performance, but may also bring risks to the environment since the fate of nanomaterials is poorly understood. This study investigated the impact of CuO nanoparticles on the germination and seedling development of Phaseolus vulgaris L. A range of nanoparticle sizes and concentrations was covered (25, 40 and <80 nm at 1, 10, 100 and 1,000 mg Cu L-1). Nanoparticles did not affect seed germination, but seedling weight gain was promoted by 100 mg Cu L-1 and inhibited by 1,000 mg Cu L-1 of 25 nm Cu and CuSO4...
August 17, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28817279/soft-chemical-fabrication-of-iron-based-thin-film-electrocatalyst-for-water-oxidation-under-neutral-ph-and-structure-activity-tuning-by-cerium-incorporation
#6
Jony Saha, T P Radhakrishnan
Design of electrocatalysts for the fundamentally important oxygen evolution reaction can be greatly aided by systematic structure-activity tuning via composition variation. We have explored the iron-cerium system as they are the most abundant transition and rare earth metals, and also due to the mutualistic impact of their size and electronic attributes that can induce critical changes in the structure and electrochemical activity. Submicrometer thick films of a series of Fe(III)-Ce(III) phosphate(oxyhydroxide) (FeCePH) are fabricated using a soft chemical strategy involving surfactant-aided assembly, spin-coating, and mild thermal annealing...
August 17, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28817278/unveiling-the-aggregation-of-lycopene-in-vitro-and-in-vivo-uv-vis-resonance-raman-and-raman-imaging-studies
#7
Mika Ishigaki, Phiranuphon Meksiarun, Yasutaka Kitahama, Leilei Zhang, Hideki Hashimoto, Takuma Genkawa, Yukihiro Ozaki
The present study investigates the structure of lycopene aggregates both in vitro and in vivo using ultraviolet-visible (UV-vis) and Raman spectroscopies. The electronic absorption bands of the J- and H-aggregates in vitro shift to lower and higher energies, respectively, compared to that of the lycopene monomer. Along with these results, the frequencies of the ν1 Raman bands were shifted to lower and higher frequencies, respectively. By plotting the frequencies of the ν1 Raman band against the S0 → S2 transition energy, a linear relationship between the data set with different aggregation conformations can be obtained...
August 17, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28817275/influence-of-sodium-chloride-on-the-formation-and-dissociation-behavior-of-co2-gas-hydrates
#8
Christine Carola Holzammer, Judith Maria Schicks, Stefan Will, Andreas Siegfried Braeuer
We present an experimental study on the formation and dissociation characteristics of carbon dioxide (CO2) gas hydrates using Raman spectroscopy. The CO2 hydrates were formed from sodium-chloride/water solutions with salinities of 0-10 wt-%, which were pressurized with liquid CO2 in a stirred vessel at 6 MPa and a subcooling of 9.5 K. The formation of the CO2 hydrate resulted in a hydrate gel where the solid hydrate can be considered as the continuous phase that includes small amounts of a dispersed liquid water-rich phase that has not been converted to hydrate...
August 17, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28817259/sub-20-nm-stable-micelles-based-on-a-mixture-of-coiled-coils-a-platform-for-controlled-ligand-presentation
#9
JooChuan Ang, Dan Ma, Benson Thomas Jung, Sinan Keten, Ting Xu
Ligand-functionalized, multivalent nanoparticles have been extensively studied for biomedical applications from imaging agents to drug delivery vehicles. However, the ligand cluster size is usually heterogeneous and the local valency is ill-defined. Here, we present a mixed micelle platform hierarchically self-assembled from a mixture of two amphiphilic 3-helix and 4-helix peptide-PEG-lipid hybrid conjugates. We demonstrate that the local multivalent ligand cluster size on the micelle surface can be controlled based on the coiled-coil oligomeric state...
August 17, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/28817255/nonacene-generated-by-on-surface-dehydrogenation
#10
Rafal Zuzak, Ruth Dorel, Mariusz Krawiec, Bartosz Such, Marek Kolmer, Marek Szymonski, Antonio M Echavarren, Szymon Godlewski
The on-surface synthesis of nonacene has been accomplished by dehydrogenation of an air-stable partially saturated precursor, which could be aromatized by using a combined scanning tunneling and atomic force microscope (STM/AFM) as well as by on-surface annealing. This transformation allowed the in-detail analysis of the electronic properties of nonacene molecules physisorbed on Au(111) by scanning tunneling spectroscopy (STS) measurements. The spatial mapping of molecular orbitals was corroborated by density functional theory (DFT) calculations...
August 17, 2017: ACS Nano
https://www.readbyqxmd.com/read/28817225/anionic-palladium-0-and-palladium-ii-ate-complexes
#11
Marlene Kolter, Katharina Böck, Konstantin Karaghiosoff, Konrad Koszinowski
Palladium ate complexes are frequently invoked as important intermediates in Heck and cross-coupling reactions, but so far have largely eluded a characterization at the molecular level. Here, we use electrospray-ionization mass spectrometry, electrical conductivity measurements, and NMR spectroscopy to show that the electron-poor catalyst [L₃Pd] (L = tris[3,5-bis(trifluoromethyl)-phenyl]phosphine) readily reacts with Br- ions to afford the anionic, zero-valent ate complex [L₃PdBr]-. In contrast, more electron-rich Pd catalysts display lower tendencies toward the formation of ate complexes...
August 17, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28817106/ag-coated-heterostructures-of-zno-tio%C3%A2-delaminated-montmorillonite-as-solar-photocatalysts
#12
Carolina Belver, Mariana Hinojosa, Jorge Bedia, Montserrat Tobajas, Maria Ariadna Alvarez, Vicente Rodríguez-González, Juan Jose Rodriguez
Heterostructures based on ZnO-TiO₂/delaminated montmorillonite coated with Ag have been prepared by sol-gel and photoreduction procedures, varying the Ag and ZnO contents. They have been thoroughly characterized by XRD, WDXRF, UV-Vis, and XPS spectroscopies, and N₂ adsorption, SEM, and TEM. In all cases, the montmorillonite was effectively delaminated with the formation of TiO₂ anatase particles anchored on the clay layer's surface, yielding porous materials with high surface areas. The structural and textural properties of the heterostructures synthesized were unaffected by the ZnO incorporated...
August 17, 2017: Materials
https://www.readbyqxmd.com/read/28817096/time-resolved-study-of-nanomorphology-and-nanomechanic-change-of-early-stage-mineralized-electrospun-poly-lactic-acid-fiber-by-scanning-electron-microscopy-raman-spectroscopy-and-atomic-force-microscopy
#13
Mengmeng Wang, Yin Cai, Bo Zhao, Peizhi Zhu
In this study, scanning electron microscopy (SEM), Raman spectroscopy and high-resolution atomic force microscopy (AFM) were used to reveal the early-stage change of nanomorphology and nanomechanical properties of poly(lactic acid) (PLA) fibers in a time-resolved manner during the mineralization process. Electrospun PLA nanofibers were soaked in simulated body fluid (SBF) for different periods of time (0, 1, 3, 5, 7 and 21 days) at 10 °C, much lower than the conventional 37 °C, to simulate the slow biomineralization process...
August 17, 2017: Nanomaterials
https://www.readbyqxmd.com/read/28816883/cerebral-oxygen-saturation-during-electroconvulsive-therapy-a-secondary-analysis-of-a-randomized-crossover-trial
#14
Kamath Sriganesh, Tanmay Jadhav, Sudhir Venkataramaiah, Channaveerachari Naveen Kumar, Shyamsundar Armugham, Mariamma Philip, K R Madhusudan Reddy, Jagadisha Thirthalli, G S Umamaheswara Rao
BACKGROUND: Electroconvulsive therapy (ECT) causes acute changes in cerebral perfusion and oxygenation. Near-infrared spectroscopy is a novel, noninvasive technique to assess cerebral oxygen saturation (cSO2). We hypothesized that cSO2 increases during ECT and more so with atropine premedication and decreases when systemic desaturation (peripheral oxygen saturation <90%) occurs during ECT. METHODS: We performed a secondary analysis of a randomized trial of patients undergoing ECT for psychiatric illness during a 6-month period...
August 14, 2017: Journal of Neurosurgical Anesthesiology
https://www.readbyqxmd.com/read/28816833/perioperative-use-of-erythromycin-reduces-cognitive-decline-after-coronary-artery-bypass-grafting-surgery-a-pilot-study
#15
Evanthia Thomaidou, Helena Argiriadou, Georgios Vretzakis, Kalliopi Megari, Nikolaos Taskos, Georgios Chatzigeorgiou, Kyriakos Anastasiadis
OBJECTIVES: Adverse neurologic outcome can be a debilitating complication after cardiac surgery. The aim of this study was to investigate the potential neuroprotective action of erythromycin, a well known antibiotic agent, regarding postoperative cognitive decline in patients undergoing cardiac surgery. METHODS: Forty patients scheduled for elective coronary artery bypass grafting surgery were prospectively randomly assigned in 2 groups: the erythromycin group (n = 19) who received erythromycin at a dose of 25 mg/kg before and after surgery and the control group (n = 21) who did not receive it...
August 14, 2017: Clinical Neuropharmacology
https://www.readbyqxmd.com/read/28816602/synthesis-and-in-vitro-antimicrobial-and-antioxidant-activities-of-quaternary-ammonium-chitosan-modified-with-nisin
#16
Lian Min, Meng Liu, Chen Zhu, Liangling Liu, Zhiqie Rao, Lihong Fan
Nisin had been grafted onto quaternary ammonium chitosan (QCS) through an enzyme-catalyzed reactionto enhanceitslimitedantimicrobial activity. QCS was synthesizedby incorporating N-(3-chloro-2-hydroxypropyl) trimethyl ammonium chloride(CHPTAC)ontochitosan's primary aminegroup.The modificationhad been confirmed by FT-IR and (1)H NMR spectroscopy. Degree of substitution (DS) of QCS-nisin could be controlled by adjusting the reaction conditions. The synthesized compounds were screened in vitroto evaluate their antimicrobial and antioxidant activities...
August 17, 2017: Journal of Biomaterials Science. Polymer Edition
https://www.readbyqxmd.com/read/28816458/pressure-induced-emission-enhancement-of-carbazole-the-restriction-of-intramolecular-vibration
#17
Yarong Gu, Kai Wang, Yu-Xiang Dai, Guanjun Xiao, Yuguo Ma, Yuancun Qiao, Bo Zou
Pressure-induced emission enhancement (PIEE), a novel phenomenon on the enhancement of the solid-state emission efficiency of fluorophores, has been arousing wide attention in recent years. However, researches on PIEE are still in the early stage. To further pursue more enhanced efficiency, discovering and designing more PIEE systems would be urgently desirable and of great importance. In this letter, we found carbazole presented a conspicuous emission enhancement under high pressure up to 1.0 GPa. In situ high-pressure infrared spectroscopy, angle-dispersive X-ray diffraction analysis combined with Hirshfeld surface theory calculation indicated that the PIEE of carbazole was attributed to the decrease of non-radiation vibration process...
August 17, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28816445/tracking-the-progress-and-mechanism-study-of-a-solvothermal-in-situ-domino-n-alkylation-reaction-of-triethylamine-and-ammonia-assisted-by-ferrous-sulfate
#18
Jin-Ping Zhong, Bin Liu, Tao Yang, Yue-Jin Liu, Zhong-Hong Zhu, Bing-Feng Shi, Mohamedally Kurmoo, Ming-Hua Zeng
Atom economic in situ domino N-alkylation reactions of triethylamine/ammonia with 2-(hydroxymethyl)quinolin-8-ol (HL-OH) assisted by FeSO4·7H2O were realized under mild solvothermal conditions at 120 °C in acetonitrile. The resulting tripodal 2,2',2″-[nitrilotris(methylene)]tris(quinolin-8-ol) (H3L3-N) forms a linear trimer [Fe3(L3-N)2] (1). Electrospray ionization mass spectrometry of the reaction solution provides evidence for the intermediates of three steps, while crystallography and X-ray photoelectron spectroscopy characterize the trimer...
August 17, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28816440/high-quantities-of-microplastic-in-arctic-deep-sea-sediments-from-the-hausgarten-observatory
#19
Melanie Bergmann, Vanessa Wirzberger, Thomas Krumpen, Claudia Lorenz, Sebastian Primpke, Mine B Tekman, Gunnar Gerdts
Although mounting evidence suggests the ubiquity of microplastic in aquatic ecosystems worldwide, our knowledge of its distribution in remote environments such as Polar Regions and the deep sea is scarce. Here, we analyzed nine sediment samples taken at the HAUSGARTEN observatory in the Arctic at 2,340 - 5,570 m depth. Density separation by MicroPlastic Sediment Separator and treatment with Fenton's reagent enabled analysis via Attenuated Total Reflection FTIR and µFTIR spectroscopy. Our analyses indicate the wide spread of high numbers of microplastics (42 - 6,595 microplastics kg-1)...
August 17, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28816431/carbon-nanotubes-arranged-as-smart-interfaces-in-lipid-langmuir-blodgett-films-enhancing-the-enzymatic-properties-of-penicillinase-for-biosensing-applications
#20
Fabio Scholl, Paulo Morais, Rayla Gabriel, Michael J Schöning, Jose Roberto Siqueira, Luciano Caseli
In this paper, carbon nanotubes (CNTs) were incorporated in penicillinase-phospholipid Langmuir and Langmuir-Blodgett (LB) films to enhance the enzyme catalytic properties. Adsorption of the penicillinase and CNTs at dimyristoylphosphatidic acid (DMPA) monolayers at the air-water interface was investigated by surface pressure-area isotherms, vibrational spectroscopy and Brewster angle microscopy. The floating monolayers were transferred to solid supports through the LB technique, forming mixed DMPA-CNTs-PEN films, which were investigated by quartz crystal microbalance, vibrational spectroscopy, and atomic force microscopy...
August 17, 2017: ACS Applied Materials & Interfaces
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