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https://www.readbyqxmd.com/read/29044982/surface-assisted-self-assembly-strategies-leading-to-supramolecular-hydrogels
#1
Pierre Schaaf, Cécile Vigier-Carrière, Fouzia Boulmedais, Loïc Jierry
Localized molecular self-assembly processes leading to the growth of nanostructures exclusively from the surface of a material is one of the great challenges in surface chemistry. In the last decade, several works have been reported about the ability of modified or unmodified surfaces to manage the self-assembly of low molecular weight hydrogelators (LMWH) resulting in localized supramolecular hydrogel coatings mainly based on nanofiber architectures. This minireview highlights all strategies that emerged recently to initiate and localize LMWH supramolecular hydrogel formation, their related fundamental issues and applications...
October 17, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29044719/alkyl-and-aryl-thiol-addition-to-1-1-1-propellane-scope-and-limitations-of-a-fast-conjugation-reaction
#2
Robin M Bär, Stefan Kirschner, Martin Nieger, Stefan Bräse
Herein we report the addition of different thiols to the strained carbon-carbon bond of [1.1.1]propellane (1). We investigated the reaction pathway, performed the addition with substituted thiols, hydrogen sulfide and protected cysteine and verified further modifications of the products. The clean reaction proceeds probably through a radical chain process as we confirmed with different deuterium labelling experiments. It shows great functional group tolerance as halogen-, hydroxy-, methoxy-, carboxy-, amino- and nitro-substituted thiols could be added to 1 with few by-products in 16-90% yield...
October 16, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29044437/a-novel-dihydrocoumarin-under-experimental-and-theoretical-characterization
#3
W F Vaz, J M F Custodio, N M N Rodrigues, L G Santin, S S Oliveira, R Gargano, F A P Osório, G L B Aquino, A J Camargo, M S Oliveira, H B Napolitano
Coumarins are natural and synthetic active ingredients widely applied in diverse types of medicinal treatments, such as cancer, inflammation, infection, and enzyme inhibition (monoamine oxidase B). Dihydrocoumarin compounds are of great interest in organic chemistry due to their structural versatilities and, as part of our investigations concerning the structural characterization of small molecules, this work focuses on crystal structure and spectroscopic characterization of the synthesized and crystallized compound 4-(4-methoxyphenyl)-3,4-dihydro-chromen-2-one (C16H14O3)...
October 18, 2017: Journal of Molecular Modeling
https://www.readbyqxmd.com/read/29043786/measuring-nanoparticle-attachment-efficiency-in-complex-systems
#4
Nicholas K Geitner, Niall Joseph O'Brien, Amalia Turner, Enda Cummins, Mark R Wiesner
As process-based environmental fate and transport models for engineered nanoparticles are developed, there is a need for relevant and reliable measures of nanoparticle behaviour. The affinity of nanoparticles for various surfaces (α) is one such measure. Measurements of the affinity of nanoparticles obtained by flowing particles through a porous medium are constrained by the types of materials or exposure scenarios that can be configured into such column studies. Utilizing glass beads and kaolinite as model collector surfaces, we evaluate a previously developed mixing method for measuring nanoparticle attachment to environmental surfaces, and validate this method with an equivalent static column system over a range of organic matter concentrations and ionic strengths...
October 18, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/29043780/cucurbituril-and-azide-co-functionalized-graphene-oxide-for-ultrasensitive-electro-click-biosensing
#5
Tianxiang Wei, Tingting Dong, Hong Xing, Ying Liu, Zhihui Dai
To achieve high selectivity and sensitivity simultaneously in an electrochemical biosensing platform, cucurbituril and azide co-functionalized graphene oxide, a new functional nanomaterial that acts as a go-between to connect the recognition element with amplified signal architecture, is developed in this work. The cucurbituril and azide co-functionalized graphene oxide features a high specific surface area with abundant levels of the two types of functional groups. Specifically, it emerges as a powerful tool to link recognition elements with simplicity, high yield, rapidity and highly selective reactivity through azide-alkynyl click chemistry...
October 18, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/29043353/machine-learnt-bond-order-potential-to-model-metal-organic-co-c-heterostructures
#6
Badri Narayanan, Henry Chan, Alper Kinaci, Fatih G Sen, Stephen K Gray, Maria K Y Chan, Subramanian K R S Sankaranarayanan
A fundamental understanding of the inter-relationships between structure, morphology, atomic scale dynamics, chemistry, and physical properties of mixed metallic-covalent systems is essential to design novel functional materials for applications in flexible nano-electronics, energy storage and catalysis. To achieve such knowledge, it is imperative to develop robust and computationally efficient atomistic models that describe atomic interactions accurately within a single framework. Here, we present a unified Tersoff-Brenner type bond order potential (BOP) for a Co-C system, trained against lattice parameters, cohesive energies, equation of state, and elastic constants of different crystalline phases of cobalt as well as orthorhombic Co2C derived from density functional theory (DFT) calculations...
October 18, 2017: Nanoscale
https://www.readbyqxmd.com/read/29041272/transition-between-bulk-and-surface-refractive-index-sensitivity-of-micro-cavity-in-line-mach-zehnder-interferometer-induced-by-thin-film-deposition
#7
Mateusz Śmietana, Monika Janik, Marcin Koba, Wojtek J Bock
In this work we discuss the refractive index (RI) sensitivity of a micro-cavity in-line Mach-Zehnder interferometer in the form of a cylindrical hole (40-50 μm in diameter) fabricated in a standard single-mode optical fiber using a femtosecond laser. The surface of the micro-cavity was coated with up to 400 nm aluminum oxide thin film using the atomic layer deposition method. Next, the film was progressively chemically etched and the influence on changes in the RI of liquid in the micro-cavity was determined at different stages of the experiment, i...
October 16, 2017: Optics Express
https://www.readbyqxmd.com/read/29040874/surface-functionalized-exosomes-as-targeted-drug-delivery-vehicles-for-cerebral-ischemia-therapy
#8
Tian Tian, Hui-Xin Zhang, Chun-Peng He, Song Fan, Yan-Liang Zhu, Cui Qi, Ning-Ping Huang, Zhong-Dang Xiao, Zu-Hong Lu, Bakhos A Tannous, Jun Gao
The safe and effective delivery of drugs is a major obstacle in the treatment of ischemic stroke. Exosomes hold great promise as an endogenous drug delivery nanosystem for the treatment of cerebral ischemia given their unique properties, including low immunogenicity, innate stability, high delivery efficiency, and ability to cross the blood-brain barrier (BBB). However, exosome insufficient targeting capability limits their clinical applications. In this study, the c(RGDyK) peptide has been conjugated to the exosome surface by an easy, rapid, and bio-orthogonal chemistry...
October 4, 2017: Biomaterials
https://www.readbyqxmd.com/read/29039819/single-domain-antibodies-as-new-biomarker-detectors
#9
REVIEW
Chiuan Herng Leow, Katja Fischer, Chiuan Yee Leow, Qin Cheng, Candy Chuah, James McCarthy
Biomarkers are defined as indicators of biological processes, pathogenic processes, or pharmacological responses to a therapeutic intervention. Biomarkers have been widely used for early detection, prediction of response after treatment, and for monitoring the progression of diseases. Antibodies represent promising tools for recognition of biomarkers, and are widely deployed as analytical tools in clinical settings. For immunodiagnostics, antibodies are now exploited as binders for antigens of interest across a range of platforms...
October 17, 2017: Diagnostics
https://www.readbyqxmd.com/read/29038552/regulating-p-block-metals-in-perovskite-nanodots-for-efficient-electrocatalytic-water-oxidation
#10
Bo-Quan Li, Zi-Jing Xia, Bingsen Zhang, Cheng Tang, Hao-Fan Wang, Qiang Zhang
Water oxidation represents the core process of many sustainable energy systems, such as fuel cells, rechargeable metal-air batteries, and water splitting. Material surface defects with high-energy hanging bonds possess superb intrinsic reactivity, whose actual performance is limited by the dimension and conductivity of the electrocatalyst. Herein we propose a surface defect-rich perovskite electrocatalyst through a p-block metal regulation concept to achieve high performance for oxygen evolution. As a typical p-metal, Sn(4+) dissolves from the solid phase from model SnNiFe perovskite nanodots, resulting in abundant surface defects with superior water oxidation performance...
October 16, 2017: Nature Communications
https://www.readbyqxmd.com/read/29038475/climate-and-permafrost-effects-on-the-chemistry-and-ecosystems-of-high-arctic-lakes
#11
K E Roberts, S F Lamoureux, T K Kyser, D C G Muir, M J Lafrenière, D Iqaluk, A J Pieńkowski, A Normandeau
Permafrost exerts an important control over hydrological processes in Arctic landscapes and lakes. Recent warming and summer precipitation has the potential to alter water availability and quality in this environment through thermal perturbation of near surface permafrost and increased mobility of previously frozen solutes to Arctic freshwaters. We present a unique thirteen-year record (2003-16) of the physiochemical properties of two High Arctic lakes and show that the concentration of major ions, especially SO4(2-), has rapidly increased up to 500% since 2008...
October 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29038377/recent-development-of-nanoparticles-for-molecular-imaging
#12
REVIEW
Jonghoon Kim, Nohyun Lee, Taeghwan Hyeon
Molecular imaging enables us to non-invasively visualize cellular functions and biological processes in living subjects, allowing accurate diagnosis of diseases at early stages. For successful molecular imaging, a suitable contrast agent with high sensitivity is required. To date, various nanoparticles have been developed as contrast agents for medical imaging modalities. In comparison with conventional probes, nanoparticles offer several advantages, including controllable physical properties, facile surface modification and long circulation time...
November 28, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/29038376/development-of-cyanine-probes-with-dinitrobenzene-quencher-for-rapid-fluorogenic-protein-labelling
#13
Yuichiro Hori, Shinya Hirayama, Kazuya Kikuchi
A multicolour protein labelling technique using a protein tag and fluorogenic probes is a powerful approach for spatio-temporal analyses of proteins in living cells. Since cyanine fluorophores have attractive properties for multicolour imaging of proteins, there is a huge demand to develop fluorogenic cyanine probes for specific protein labelling in living cells. Herein, we develop fluorogenic cyanine probes for labelling a protein tag by using a dinitrobenzene fluorescence quencher. The probes enhanced fluorescence intensity upon labelling reactions and emitted orange or far-red fluorescence...
November 28, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/29035268/trace-element-and-isotope-deposition-across-the-air-sea-interface-progress-and-research-needs
#14
REVIEW
A R Baker, W M Landing, E Bucciarelli, M Cheize, S Fietz, C T Hayes, D Kadko, P L Morton, N Rogan, G Sarthou, R U Shelley, Z Shi, A Shiller, M M P van Hulten
The importance of the atmospheric deposition of biologically essential trace elements, especially iron, is widely recognized, as are the difficulties of accurately quantifying the rates of trace element wet and dry deposition and their fractional solubility. This paper summarizes some of the recent progress in this field, particularly that driven by the GEOTRACES, and other, international research programmes. The utility and limitations of models used to estimate atmospheric deposition flux, for example, from the surface ocean distribution of tracers such as dissolved aluminium, are discussed and a relatively new technique for quantifying atmospheric deposition using the short-lived radionuclide beryllium-7 is highlighted...
November 28, 2016: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/29035266/lead-isotope-exchange-between-dissolved-and-fluvial-particulate-matter-a-laboratory-study-from-the-johor-river-estuary
#15
Mengli Chen, Edward A Boyle, Jong-Mi Lee, Intan Nurhati, Cheryl Zurbrick, Adam D Switzer, Gonzalo Carrasco
Atmospheric aerosols are the dominant source of Pb to the modern marine environment, and as a result, in most regions of the ocean the Pb isotopic composition of dissolved Pb in the surface ocean (and in corals) matches that of the regional aerosols. In the Singapore Strait, however, there is a large offset between seawater dissolved and coral Pb isotopes and that of the regional aerosols. We propose that this difference results from isotope exchange between dissolved Pb supplied by anthropogenic aerosol deposition and adsorbed natural crustal Pb on weathered particles delivered to the ocean by coastal rivers...
November 28, 2016: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/29035261/the-effect-of-acidification-on-the-bioavailability-and-electrochemical-lability-of-zinc-in-seawater
#16
Ja-Myung Kim, Oliver Baars, François M M Morel
A poorly studied but potentially important consequence of the CO2-induced acidification of the surface ocean is a possible change in the bioavailability of trace metals, which play a critical role in the productivity and population dynamics of marine ecosystems. We report laboratory and field experiments designed to compare quantitatively the effects of acidification on the bioavailability of Zn, a metal essential to the growth of phytoplankton and on the extent of its complexation by model and natural ligands...
November 28, 2016: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/29035255/diagnosing-oceanic-nutrient-deficiency
#17
C Mark Moore
The supply of a range of nutrient elements to surface waters is an important driver of oceanic production and the subsequent linked cycling of the nutrients and carbon. Relative deficiencies of different nutrients with respect to biological requirements, within both surface and internal water masses, can be both a key indicator and driver of the potential for these nutrients to become limiting for the production of new organic material in the upper ocean. The availability of high-quality, full-depth and global-scale datasets on the concentrations of a wide range of both macro- and micro-nutrients produced through the international GEOTRACES programme provides the potential for estimation of multi-element deficiencies at unprecedented scales...
November 28, 2016: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/29035055/atmospheric-simulation-chamber-studies-of-the-gas-phase-photolysis-of-pyruvic-acid
#18
Allison Early Reed Harris, Mathieu Cazaunau, Aline Gratien, Edouard Pangui, Jean-Francois Doussin, Veronica Vaida
Pyruvic acid is an atmospherically-abundant α-keto-acid that degrades efficiently from the troposphere via gas-phase photolysis. In order to explore conditions relevant to the environment, 2-12 ppm pyruvic acid is irradiated by a solar simulator in the environmental simulation chamber, CESAM. The combination of the long path length available in the chamber and its low surface area to volume ratio allow us to quantitatively examine the quantum yield and photochemical products of pyruvic acid. Such details are new to the literature for the low initial concentrations of pyruvic acid employed here...
October 16, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29034601/contact-active-antimicrobial-coatings-prepared-by-polymer-blending
#19
Rocío Cuervo-Rodríguez, Fátima López-Fabal, José L Gómez-Garcés, Alexandra Muñoz-Bonilla, Marta Fernández-García
Herein, contact active antimicrobial films are prepared by simply blending cationic amphiphilic block copolymers with commercial polystyrene (PS). The copolymers are prepared by combining atom transfer radical polymerization and "click chemistry." A variety of copolymers are synthesized, and composed of a PS segment and an antimicrobial block bearing flexible side chain with thiazole and triazole groups, 4-(1-(2-(4-methylthiazol-5-yl)ethyl)-1H-1,2,3-triazol-4-yl) butyl methacrylate (TTBM). The length of the TTBM block is varied as well as the alkylating agent...
October 16, 2017: Macromolecular Bioscience
https://www.readbyqxmd.com/read/29034467/first-insights-into-the-function-of-the-sawshark-rostrum-through-examination-of-rostral-tooth-microwear
#20
R J Nevatte, B E Wueringer, D E Jacob, J M Park, J E Williamson
Potential roles of the rostrum of sawsharks (Pristiophoridae), including predation and self-defence, were assessed through a variety of inferential methods. Comparison of microwear on the surface of the rostral teeth of sawsharks and sawfishes (Pristidae) show that microwear patterns are alike and suggest that the elongate rostra in these two elasmobranch families are used for a similar purpose (predation). Raman spectroscopy indicates that the rostral teeth of both sawsharks and sawfishes are composed of hydroxyapatite, but differ in their collagen content...
October 16, 2017: Journal of Fish Biology
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