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Systems chemistry

Sanna Rauhamäki, Pekka A Postila, Sanna Niinivehmas, Sami Kortet, Emmi Schildt, Mira Pasanen, Elangovan Manivannan, Mira Ahinko, Pasi Koskimies, Niina Nyberg, Pasi Huuskonen, Elina Multamäki, Markku Pasanen, Risto O Juvonen, Hannu Raunio, Juhani Huuskonen, Olli T Pentikäinen
Monoamine oxidase B (MAO-B) catalyzes deamination of monoamines such as neurotransmitters dopamine and norepinephrine. Accordingly, small-molecule MAO-B inhibitors potentially alleviate the symptoms of dopamine-linked neuropathologies such as depression or Parkinson's disease. Coumarin with a functionalized 3-phenyl ring system is a promising scaffold for building potent MAO-B inhibitors. Here, a vast set of 3-phenylcoumarin derivatives was designed using virtual combinatorial chemistry or rationally de novo and synthesized using microwave chemistry...
2018: Frontiers in Chemistry
Sidónio C Freitas, Alejandra Correa-Uribe, M Cristina L Martins, Alejandro Pelaez-Vargas
Implant-based therapy is a mature approach to recover the health conditions of patients affected by edentulism. Thousands of dental implants are placed each year since their introduction in the 80s. However, implantology faces challenges that require more research strategies such as new support therapies for a world population with a continuous increase of life expectancy, to control periodontal status and new bioactive surfaces for implants. The present review is focused on self-assembled monolayers (SAMs) for dental implant materials as a nanoscale-processing approach to modify titanium surfaces...
2018: International Journal of Dentistry
Vibhuti Agrahari, Vivek Agrahari
Block copolymers are widely utilized in the design of nanoformulations owing to their excellent physicochemical properties, flexible structure and functional chemistry. Advances in polymer synthetic approaches have significantly enhanced the ability to rationally design the block copolymers with tailor-made functionality and variable molecular weight. Hence, block copolymers have been extensively applied in the formulation of nanostructure materials. In this review, block copolymer classification, synthesis, characterization, stimuli-responsive behavior and nanostructure applications are summarized...
March 15, 2018: Drug Discovery Today
Samaresh Sau, Katyayani Tatiparti, Hashem O Alsaab, Sushil K Kashaw, Arun K Iyer
Nanomedicines can be multifunctional drug delivery agents for cancer therapies. However, they have faced several challenges in clinical trials owing to poor targeting ability, insufficient tumor penetration, difficulty in synthesis and scale up, and limited understanding of interactions between a tumor and nanoparticles. In this regard, tumor muticomponent targeting drug delivery systems are a rational approach for developing tumor-site-specific therapeutics. One of the goals is to arrive at a ready-to-configure, combinatorial, reagent-free click-chemistry-based tumor multicomponent targeting nanoparticle library...
March 15, 2018: Drug Discovery Today
Aritri Sanyal, Runa Antony, Gautami Samui, Meloth Thamban
Cryoconite holes (cylindrical melt-holes on the glacier surface) are important hydrological and biological systems within glacial environments that support diverse microbial communities and biogeochemical processes. This study describes retrievable heterotrophic microbes in cryoconite hole water from three geographically distinct sites in Antarctica, and a Himalayan glacier, along with their potential to degrade organic compounds found in these environments. Microcosm experiments (22 days) show that 13-60% of the dissolved organic carbon in the water within cryoconite holes is bio-available to resident microbes...
March 2018: Microbiological Research
Etienne Jambon-Puillet, Christophe Josserand, Suzie Protiere
Solid particles can modify the properties of liquid interfaces and are therefore widely used to coat drops, bubbles and stabilize emulsions and foams. Here we propose a new, easy and affordable method to produce millimetric to centimetric water-in-water capsules using solid particles. We prevent the coalescence of a water drop at an oil-water interface using a monolayer of large, dense and hydrophobic particles: a ``granular raft''. The capsule is then formed by a mechanical instability occurring when the interface collapses under the combined load of the floating drop and particle weight...
March 19, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
André Campaniço, Rui Moreira, Francisca Lopes
Tuberculosis (TB) remains a major health problem worldwide. The infectious agent, Mycobacterium tuberculosis, has a unique ability to survive within the host, alternating between active and latent disease states, and escaping the immune system defences. The extended duration of anti-TB regimens and the increasing prevalence of multidrug- (MDR) and extensively drug-resistant (XDR) M. tuberculosis strains have created an urgent need for new antibiotics active against drug-resistant organisms and that can shorten standard therapy...
March 9, 2018: European Journal of Medicinal Chemistry
Mel O'Leary, Daria Boscolo, Nicole Breslin, Jeremy M C Brown, Igor P Dolbnya, Chris Emerson, Catarina Figueira, Oliver J L Fox, David Robert Grimes, Vladimir Ivosev, Annette K Kleppe, Aaron McCulloch, Ian Pape, Chris Polin, Nathan Wardlow, Fred J Currell
Absolute measurements of the radiolytic yield of Fe3+ in a ferrous sulphate dosimeter formulation (6 mM Fe2+), with a 20 keV x-ray monoenergetic beam, are reported. Dose-rate suppression of the radiolytic yield was observed at dose rates lower than and different in nature to those previously reported with x-rays. We present evidence that this effect is most likely to be due to recombination of free radicals radiolytically produced from water. The method used to make these measurements is also new and it provides radiolytic yields which are directly traceable to the SI standards system...
March 16, 2018: Scientific Reports
Mohamed Bayati, Jingjing Dai, Austin Zambrana, Chloe Rees, Maria Fidalgo de Cortalezzi
Carbon dots are rapidly emerging carbon-based nanomaterials that, due to their growing applications, will inevitable find their way to natural waters; however, their environmental fate is mostly unknown. Carbon dots with different surface functionality were fabricated and characterized by TEM and FT-IR. Their surface charge, given by the zeta potential, and their hydrodynamic diameter in suspension were investigated under a variety of environmentally relevant conditions. The effect of ionic strength was studied in the presence of monovalent (NaCl) and divalent (CaCl2 ) cations, for pH levels from 3 to 11; humic acid was used as a model for dissolved natural organic matter...
March 2018: Journal of Environmental Sciences (China)
Teruaki Okushima, Tomoaki Niiyama, Kensuke S Ikeda, Yasushi Shimizu
Understanding the slowest relaxations of complex systems, such as relaxation of glass-forming materials, diffusion in nanoclusters, and folding of biomolecules, is important for physics, chemistry, and biology. For a kinetic system, the relaxation modes are determined by diagonalizing its transition rate matrix. However, for realistic systems of interest, numerical diagonalization, as well as extracting physical understanding from the diagonalization results, is difficult due to the high dimensionality. Here, we develop an alternative and generally applicable method of extracting the long-time scale relaxation dynamics by combining the metabasin analysis of Okushima et al...
February 2018: Physical Review. E
Li-Hui Mou, Qing-Yu Liu, Ting Zhang, Zi-Yu Li, Sheng-Gui He
Dinitrogen activation/fixation is one of the most important and challenging subjects in synthetic as well as theoretical chemistry. In this study, the adsorption reactions of N2 onto TaCn - ( n = 1-4) cluster anions have been investigated by means of mass spectrometry in conjunction with density functional theory calculations. Following the experimental results that only TaC4 - was observed to adsorb N2 , theoretical calculations predicted that TaC4 - reaction system (TaC4 - + N2 → TaC4 N2 - ) has a negligible barrier on the approach of N2 molecule while insurmountable barriers are located on the reaction pathways of TaC1-3 - /N2 reaction systems...
March 16, 2018: Journal of Physical Chemistry. A
Wesley D Allen
The overarching analytic integrated rate equation for the chemical kinetics of any reversible or irreversible reaction involving an arbitrary number of species and any integral orders is shown to be [EQN1], where ξ(t) is the extent of reaction variable, the fi are roots of a polynomial of order r, the exponents are determined by [EQN2] , and F0 is a factor involving the stoichiometric coefficients and rate constants (k± ). All integrated rate equations of elementary reactions appearing in chemical kinetics are special cases of this universal solution...
March 16, 2018: Journal of Physical Chemistry. A
Manisha B Walunj, Arun A Tanpure, Seergazhi G Srivatsan
Pd-catalyzed C-C bond formation, an important vertebra in the spine of synthetic chemistry, is emerging as a valuable chemoselective transformation for post-synthetic functionalization of biomacromolecules. While methods are available for labeling protein and DNA, development of an analogous procedure to label RNA by cross-coupling reactions remains a major challenge. Herein, we describe a new Pd-mediated RNA oligonucleotide (ON) labeling method that involves post-transcriptional functionalization of iodouridine-labeled RNA transcripts by using Suzuki-Miyaura cross-coupling reaction...
March 13, 2018: Nucleic Acids Research
Debra A Davis, Sparkle L Malone, Charles R Lovell
Drought has many consequences in the tidally dominated Spartina sp. salt marshes of the southeastern US; including major dieback events, changes in sediment chemistry and obvious changes in the landscape. These coastal systems tend to be highly productive, yet many salt marshes are also nitrogen limited and depend on plant associated diazotrophs as their source of 'new' nitrogen. A 4-year study was conducted to investigate the structure and composition of the rhizosphere diazotroph assemblages associated with 5 distinct plant zones in one such salt marsh...
March 15, 2018: Microorganisms
Lu Han, Shunai Che
Triply periodic minimal surface structures and related geometries are widely identified in many natural systems, such as biological membranes and biophotonic structures in butterfly-wing scales. Inspired by their marvelous and highly symmetrical structures and optimized physical properties, these structures have sparked immense interest for creating novel materials by extracting the design from nature. Significant progress has been made to understand these biological structures and fabricate artificial materials by top-down and bottom-up approaches for numerous applications in chemistry and materials science...
March 15, 2018: Advanced Materials
Thai M Hoang, Rui Pan, Jonghoon Ahn, Jaehoon Bang, H T Quan, Tongcang Li
Nonequilibrium processes of small systems such as molecular machines are ubiquitous in biology, chemistry, and physics but are often challenging to comprehend. In the past two decades, several exact thermodynamic relations of nonequilibrium processes, collectively known as fluctuation theorems, have been discovered and provided critical insights. These fluctuation theorems are generalizations of the second law and can be unified by a differential fluctuation theorem. Here we perform the first experimental test of the differential fluctuation theorem using an optically levitated nanosphere in both underdamped and overdamped regimes and in both spatial and velocity spaces...
February 23, 2018: Physical Review Letters
Haeree Park, Yeongkyu Choi, M T Jeena, Eungjin Ahn, Yuri Choi, Myeong-Gyun Kang, Chae Gyu Lee, Tae-Hyuk Kwon, Hyun-Woo Rhee, Ja-Hyoung Ryu, Byeong-Su Kim
Owing to the unique advantages of combining the characteristics of hydrogels and nanoparticles, nanogels are actively investigated as a promising platform for advanced biomedical applications. In this work, a self-cross-linked hyperbranched polyglycerol nanogel is synthesized using the thiol-disulfide exchange reaction based on a novel disulfide-containing polymer. A series of structural analyses confirm the tunable size and cross-linking density depending on the type of polymer (homo- or copolymer) and the amount of reducing agent, dithiothreitol, used in the preparation of the nanogels...
March 15, 2018: Macromolecular Bioscience
Daniel T Allen, Nikou Damestani, Yussif Saaka, M Jayne Lawrence, Christian D Lorenz
A series of atomistic molecular dynamics simulations were performed for investigating the interactions between three different testosterone-based compounds (testosterone (T), testosterone propionate (TP) and testosterone enanthate (TE)) and sodium dodecyl sulphate (SDS) and ammonium dodecyl sulphate (ADS) monolayers, which vary only in the sodium or ammonium counterions used to neutralise the sulphate headgroup. These simulations were used to investigate how the structural and interfacial properties of the monolayer were affected by changing the number of drug molecules present per monolayer, and the chemical nature of the surfactant counterions and the testosterone-based compounds...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
David R Glenn, Dominik B Bucher, Junghyun Lee, Mikhail D Lukin, Hongkun Park, Ronald L Walsworth
Quantum systems that consist of solid-state electronic spins can be sensitive detectors of nuclear magnetic resonance (NMR) signals, particularly from very small samples. For example, nitrogen-vacancy centres in diamond have been used to record NMR signals from nanometre-scale samples, with sensitivity sufficient to detect the magnetic field produced by a single protein. However, the best reported spectral resolution for NMR of molecules using nitrogen-vacancy centres is about 100 hertz. This is insufficient to resolve the key spectral identifiers of molecular structure that are critical to NMR applications in chemistry, structural biology and materials research, such as scalar couplings (which require a resolution of less than ten hertz) and small chemical shifts (which require a resolution of around one part per million of the nuclear Larmor frequency)...
March 14, 2018: Nature
Peixuan Xia, Shihua Chu, Geng Liu, Guoqing Chen, Tao Yi, Shi Feng, Hongying Zhou
Kinesin Family Member 3A (KIF3A) was recognized as a key factor of ciliogenesis and transport system of primary cilia in normal cells. However, its possible function on cancer cells has yet to be identified. In the present study, microarray tissue chips, including 230 breast cancer samples, were applied to determine the KIF3A expression pattern by immunological histological chemistry. Statistical analysis on the KIF3A expression level and the currently used clinicopathological characteristics of breast cancer patients was carried out...
April 2018: Biomedical Reports
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