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https://www.readbyqxmd.com/read/28548169/photophysicochemical-characterization-of-mycosporine-like-amino-acids-in-micellar-solutions
#1
D E Orallo, S G Bertolotti, M S Churio
The properties and photochemical and photophysical behavior of the mycosporine-like amino acids (MAAs) shinorine and porphyra-334 were experimentally evaluated in solutions of direct ionic micelles as simple biomimicking environments. The preferential partition of the natural molecules in the aqueous phase of sodium dodecyl sulfate (SDS) or cetyltrimethylammonium chloride (CTAC) micellar systems is confirmed. Although the proton dissociation of the carboxylic groups in the MAAs is slightly inhibited in CTAC solutions, the molecules are predicted to be in the form of zwitterions in all the explored media around physiological pH...
May 26, 2017: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28546846/metal-free-hydroarylation-of-the-side-chain-carbon-carbon-double-bond-of-5-2-arylethenyl-3-aryl-1-2-4-oxadiazoles-in-triflic-acid
#2
Anna S Zalivatskaya, Dmitry S Ryabukhin, Marina V Tarasenko, Alexander Yu Ivanov, Irina A Boyarskaya, Elena V Grinenko, Ludmila V Osetrova, Eugeniy R Kofanov, Aleksander V Vasilyev
The metal-free reaction of 5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles with arenes in neat triflic acid (TfOH, CF3SO3H), both under thermal and microwave conditions, leads to 5-(2,2-diarylethyl)-3-aryl-1,2,4-oxadiazoles. The products are formed through the regioselective hydroarylation of the side chain carbon-carbon double bond of the starting oxadiazoles in yields up to 97%. According to NMR data and DFT calculations, N(4),C-diprotonated forms of oxadiazoles are the electrophilic intermediates in this reaction...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28544001/lipophilic-n-hydroxyphthalimide-catalysts-for-the-aerobic-oxidation-of-cumene-towards-solvent-free-conditions-and-back
#3
Manuel Petroselli, Lucio Melone, Massimo Cametti, Carlo Punta
A new class of lipophilic N-hydroxyphthalimides catalysts designed for the aerobic oxidation of cumene in solvent-free conditions were synthesized and tested. The specific strategy proposed for the introduction of lipophilic tails on the NHPI moiety leads to lipophilic catalysts which, while completely preserving the activity of the precursor, allow to conduct the catalytic oxidation in neat cumene for the very first time. The corresponding cumyl hydroperoxide is obtained in good yields (28-52%) and high selectivity (95-97%), under mild conditions...
May 24, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28541950/high-performance-cellulose-acetate-polysulfone-blend-ultrafiltration-membranes-for-removal-of-heavy-metals-from-water
#4
Pourya Moradihamedani, Abdul Halim Abdullah
Neat cellulose acetate (CA) and CA/polysulfone (PSf) blend ultrafiltration membranes in the presence of polyvinylpyrrolidone as a pore former were prepared via a phase inversion technique. The prepared membranes were characterized by Fourier transform infrared, scanning electron microscopy, mechanical strength, water content, porosity, permeate flux and heavy metals (Pb(2+), Cd(2+), Zn(2+) and Ni(2+)) rejection to comprehend the impact of polymer blend composition and additive on the properties of the modified membranes...
May 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
https://www.readbyqxmd.com/read/28540952/investigating-the-effect-of-ionic-strength-on-the-suppression-of-dendrite-formation-during-metal-electrodeposition
#5
Andrew K Pearson, Pon Kao, Anthony P O'Mullane, Anand I Bhatt
The effect of ionic strength on the electrodeposition of silver has been investigated in acetonitrile (MeCN) containing TBAPF6 or in the ionic liquid [EMIm][OTf]. The use of an ionic liquid allows a greater ionic strength to be investigated as the solubility limits of supporting electrolytes in organic solvents can be overcome using neat ionic liquid. The SEM and XRD data show that polycrystalline silver is deposited in a fcc structure and that dendrite formation is retarded at high ionic strength. Electrochemical measurements undertaken in electrolytes of low ionic strength indicate that the deposition and growth of a few nuclei is preferred and leads to dendrite formation...
May 25, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28540581/streptococcus-mutans-adherence-and-biofilm-formation-on-experimental-composites-containing-dicalcium-phosphate-dihydrate-nanoparticles
#6
Andrei C Ionescu, Sebastian Hahnel, Gloria Cazzaniga, Marco Ottobelli, Roberto Ruggiero Braga, Marcela Charantola Rodrigues, Eugenio Brambilla
This study aimed at evaluating bacterial adhesion and biofilm formation on resin-based composites (RBC) including dicalcium phosphate dihydrate nanoparticles (nDCPD). METHODS: Specimens were prepared from experimental RBCs with BisGMA/TEGDMA resin matrix including 20 vol% of either nDCPD (nDCPD-RBC), TEGDMA-functionalized nDPCD (F-nDCPD-RBC) or silanized silica (SiO2-RBC). Neat resin blend (control-Resin), conventional nanohybrid RBC (control-RBC) and human enamel were used for reference...
July 2017: Journal of Materials Science. Materials in Medicine
https://www.readbyqxmd.com/read/28534631/photochemical-formation-of-anthracene-quinone-methide-derivatives
#7
Djani Skalamera, Kata Mlinarić-Majerski, Irena Martin Kleiner, Marijeta Kralj, Jessy Oake, Peter Wan, Cornelia Bohne, Nikola Basaric
Anthrols 2-7 were synthesized and their photochemical reactivity investigated by irradiations in aq. CH3OH. Upon excitation with visible light (λ > 400 nm) in methanolic solutions they undergo photodehydration or photodeamination and deliver methyl ethers, most probably via quinone methides (QMs), with methanolysis quantum efficiencies ΦR = 0.02-0.3. Photophysical properties of 2-7 were determined by steady-state fluorescence and time-correlated single photon counting. Generally, anthrols 2-7 are highly fluorescent in aprotic solvents (ΦF = 0...
May 23, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28534286/development-of-a-novel-resin-based-dental-material-with-dual-biocidal-modes-and-sustained-release-of-ag-ions-based-on-photocurable-core-shell-agbr-cationic-polymer-nanocomposites
#8
Weiwei Cao, Yu Zhang, Xi Wang, Yinyan Chen, Qiang Li, Xiaodong Xing, Yuhong Xiao, Xuefeng Peng, Zhiwen Ye
Research on the incorporation of cutting-edge nano-antibacterial agent for designing dental materials with potent and long-lasting antibacterial property is demanding and provoking work. In this study, a novel resin-based dental material containing photocurable core-shell AgBr/cationic polymer nanocomposite (AgBr/BHPVP) was designed and developed. The shell of polymerizable cationic polymer not only provided non-releasing antibacterial capability for dental resins, but also had the potential to polymerize with other methacrylate monomers and prevented nanoparticles from aggregating in the resin matrix...
July 2017: Journal of Materials Science. Materials in Medicine
https://www.readbyqxmd.com/read/28533457/the-perfection-of-mimicry-an-information-approach
#9
REVIEW
Thomas N Sherratt, Casey A Peet-Paré
We consider why imperfect deceptive mimics can persist when it appears to be in the predator's interest to discriminate finely between mimics and their models. One theory is that a receiver will accept being duped if the model and mimic overlap in appearance and the relative costs of attacking the model are high. However, a more fundamental explanation for the difficulty of discrimination is not based on perceptual uncertainty, but simply based on a lack of information. In particular, predators in the process of learning may cease sampling imperfect mimics entirely because the immediate pay-off and future value of information is low, allowing such mimics to persist...
July 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28532119/poly-d-l-lactide-polycaprolactone-bioactive-glasss-nanocomposites-materials-for-anterior-cruciate-ligament-reconstruction-screws-the-effect-of-glass-surface-functionalization-on-mechanical-properties-and-cell-behaviors
#10
Javad Esmaeilzadeh, Saeed Hesaraki, Seyed Mohammad-Mehdi Hadavi, Mohammad Hosein Ebrahimzadeh, Masoud Esfandeh
In this paper, different nanocomposites made of a polymer blend (80% of PDLLA and 20% of PCL in w/w) and various amounts of a sol-gel derived bioactive glass nanoparticles (0, 1, 3 and 6wt%) were prepared using a solvent-evaporation technique. The morphology, mechanical properties and osteoblastic cell behaviors of the nanocomposites were evaluated. According to the early results, addition of bioactive glass nanoparticles to the polymer matrix reduced the tensile and flexural strength because of a non-uniform distribution of the nanoparticles...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532067/development-of-biocompatible-and-safe-polyethersulfone-hemodialysis-membrane-incorporated-with-functionalized-multi-walled-carbon-nanotubes
#11
Muhammad Nidzhom Zainol Abidin, Pei Sean Goh, Ahmad Fauzi Ismail, Mohd Hafiz Dzarfan Othman, Hasrinah Hasbullah, Noresah Said, Siti Hamimah Sheikh Abdul Kadir, Fatmawati Kamal, Mohd Sohaimi Abdullah, Be Cheer Ng
A novel approach in the design of a safe, high performance hemodialysis membrane is of great demand. Despite many advantages, the employment of prodigious nanomaterials in hemodialysis membrane is often restricted by their potential threat to health. Hence, this work focusses on designing a biocompatible polyethersulfone (PES) hemodialysis membrane embedded with poly (citric acid)-grafted-multi walled carbon nanotubes (PCA-g-MWCNTs). Two important elements which could assure the safety of the nanocomposite membrane, i...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28527458/conformation-change-of-an-isotactic-poly-n-isopropylacrylamide-membrane-molecular-dynamics
#12
Irene Adroher-Benítez, Arturo Moncho-Jordá, Gerardo Odriozola
In this work, isotactic Poly (N-Isopropylacrylamide)-PNIPAM-in neat water and in electrolyte solutions is studied by means of molecular dynamics simulations. This is done for an infinitely diluted oligomer and for an assembly of several PNIPAM chains arranged into a planar membrane configuration with a core-shell morphology. We employed two different force fields, AMBER (assisted model building with energy refinement) and OPLS-AA (all atom - optimized potentials for liquid simulations) in combination with extended simple point charge water...
May 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28525676/dynamic-mechanical-analysis-of-carbon-nanotube-reinforced-nanocomposites
#13
Shiuh-Chuan Her, Kuan-Yu Lin
BACKGROUND: To predict the mechanical properties of multiwalled carbon nanotube (MWCNT)-reinforced polymers, it is necessary to understand the role of the nanotube-polymer interface with regard to load transfer and the formation of the interphase region. The main objective of this study was to explore and attempt to clarify the reinforcement mechanisms of MWCNTs in epoxy matrix. METHODS: Nanocomposites were fabricated by adding different amounts of MWCNTs to epoxy resin...
May 18, 2017: Journal of Applied Biomaterials & Functional Materials
https://www.readbyqxmd.com/read/28524879/energy-landscape-driven-non-equilibrium-evolution-of-inherent-structure-in-disordered-material
#14
Yue Fan, Takuya Iwashita, Takeshi Egami
Complex states in glasses can be neatly expressed by the potential energy landscape (PEL). However, because PEL is highly multi-dimensional it is difficult to describe how the system moves around in PEL. Here we demonstrate that it is possible to predict the evolution of macroscopic state in a metallic glass, such as ageing and rejuvenation, through a set of simple equations describing excitations in the PEL. The key to this simplification is the realization that the step of activation from the initial state to the saddle point in PEL and the following step of relaxation to the final state are essentially decoupled...
May 19, 2017: Nature Communications
https://www.readbyqxmd.com/read/28520555/relaxation-lifetimes-of-plasmonically-enhanced-hybrid-gold-carbon-nanotubes-systems
#15
Mareen Gläske, Manoj Kumar, Timo Bißwanger, Saulius Vaitiekenas, Cesare Soci, Rohit Narula, Annalisa Bruno, Antonio Setaro
Recently, we introduced a novel hybridization route for carbon nanotubes using gold nanoparticles, whose close proximity neatly enhances their radiative emission. Here we investigate the mechanisms behind the enhancement by monitoring the de-excitation dynamics of our π-hybrids through two-color pump-probe time-resolved spectroscopy. The de-excitation process reveals a fast component and a slow component. We find that the presence of gold prominently affects the fast processes, indicating a stronger influence of the gold nanoparticle on the intra-band non-radiative relaxation than on the inter-band recombination of the SWNT...
May 18, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28517927/stable-high-performance-flexible-photodetector-based-on-upconversion-nanoparticles-perovskite-microarrays-composite
#16
Jianbo Li, Yingli Shen, Yucheng Liu, Feng Shi, Xiaodong Ren, Tianqi Niu, Kui Zhao, Shengzhong Frank Liu
Methylammonium lead halide perovskite has emerged as a new class of low-temperature-processed high-performance semiconductors for optoelectronics, but with photoresponse limited to the UV-visible region and low environmental stability. Herein, we report a flexible planar photodetector based on MAPbI3 microarrays integrated with NaYF4:Yb/Er upconversion nanoparticles (UCns) that offers promise for future high performance and long-term environmental stability. The promise derives from the confluence of several factors, including significantly enhanced photons absorption in the visible spectrum, efficient energy transition in the near-infrared (NIR) region, and inhibition of water attack by the hydrophobic UCns capping layer...
May 25, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28514863/surface-dependent-contact-activation-of-factor-xii-and-blood-plasma-coagulation-induced-by-mixed-thiol-surfaces
#17
James W Bauer, Li-Chong Xu, Erwin A Vogler, Christopher A Siedlecki
Studies of the activation of FXII in both platelet poor plasma and in neat buffer solutions were undertaken for a series of mixed thiol self-assembled monolayers spanning a broad range of water wettability. A wide spectrum of carboxyl/methyl-, hydroxyl/methyl-, and amine/methyl-thiol modified surfaces were prepared, characterized, and then utilized as the procoagulant materials in a series of FXII activation studies. X-ray photoelectron spectroscopy was utilized to verify the sample surface's thiol composition and contact angles measured to determine the sample surface's wettability...
May 17, 2017: Biointerphases
https://www.readbyqxmd.com/read/28512709/influence-of-low-temperature-combustion-and-dimethyl-ether-diesel-blends-on-performance-combustion-and-emission-characteristics-of-common-rail-diesel-engine-a-cfd-study
#18
Venkatesh Tavareppa Lamani, Ajay Kumar Yadav, Kumar Gottekere Narayanappa
Due to presence of more oxygen, absence of carbon-carbon (C-C) bond in chemical structure, and high cetane number of dimethyl ether (DME), pollution from DME operated engine is less compared to diesel engine. Hence, the DME can be a promising alternative fuel for diesel engine. The present study emphasizes the effect of various exhaust gas recirculation (EGR) rates (0-20%) and DME/Diesel blends (0-20%) on combustion characteristics and exhaust emissions of common rail direct injection (CRDI) engine using three-dimensional computational fluid dynamics (CFD) simulation...
May 16, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28512222/looplessness-in-networks-is-linked-to-trophic-coherence
#19
Samuel Johnson, Nick S Jones
Many natural, complex systems are remarkably stable thanks to an absence of feedback acting on their elements. When described as networks these exhibit few or no cycles, and associated matrices have small leading eigenvalues. It has been suggested that this architecture can confer advantages to the system as a whole, such as "qualitative stability," but this observation does not in itself explain how a loopless structure might arise. We show here that the number of feedback loops in a network, as well as the eigenvalues of associated matrices, is determined by a structural property called trophic coherence, a measure of how neatly nodes fall into distinct levels...
May 16, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28511864/metabolism-and-disposition-of-14-c-methycyclosiloxanes-in-rats
#20
Jeanne Y Domoradzki, Christopher M Sushynski, Jacob M Sushynski, Debra A McNett, Cynthia Van Landingham, Kathleen P Plotzke
Octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) are low molecular weight cyclic volatile methyl siloxanes (cVMSs) primarily used as intermediates or monomers in the production of high molecular weight silicone polymers. The use of D4 as a direct ingredient in personal care products has declined significantly over the past 10 years, although it may be present as a residual impurity in a variety of consumer products. D5 is still used as an intentional ingredient in cosmetics, consumer products and in dry cleaning...
May 13, 2017: Toxicology Letters
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