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Organic chemistry*

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https://www.readbyqxmd.com/read/28429776/global-distribution-of-particle-phase-state-in-atmospheric-secondary-organic-aerosols
#1
Manabu Shiraiwa, Ying Li, Alexandra P Tsimpidi, Vlassis A Karydis, Thomas Berkemeier, Spyros N Pandis, Jos Lelieveld, Thomas Koop, Ulrich Pöschl
Secondary organic aerosols (SOA) are a large source of uncertainty in our current understanding of climate change and air pollution. The phase state of SOA is important for quantifying their effects on climate and air quality, but its global distribution is poorly characterized. We developed a method to estimate glass transition temperatures based on the molar mass and molecular O:C ratio of SOA components, and we used the global chemistry climate model EMAC with the organic aerosol module ORACLE to predict the phase state of atmospheric SOA...
April 21, 2017: Nature Communications
https://www.readbyqxmd.com/read/28429029/derivatization-and-interlaminar-debonding-of-graphite-iron-nanoparticle-hybrid-interfaces-using-fenton-chemistry
#2
Neha Agarwal, Ruma Bhattacharyya, Narendra K Tripathi, Sanjay Kanojia, Debmalya Roy, Kingsuk Mukhopadhyay, Namburi Eswara Prasad
The interfacial debonding of graphite lattices using iron (Fe) nanoparticles and Fenton's reagent is reported, towards the scalable production of few-layer graphene flakes. Acoustic cavitation via a sonochemical route was adapted to produce iron and iron oxide nanoparticles in the graphite matrix. The oxygenated species were introduced into the graphite lattice using a physical method, and then Fenton chemistry was utilized to generate localized hydroxyl radicals at the Fe nanoparticle-graphite interfaces for zipping and self-exfoliation of the defected graphite lattices...
April 21, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28428445/pectinase-treated-panax-ginseng-protects-heat-stress-induced-testicular-damage-in-rats
#3
Min Kyoung Kim, Kyu-Min Cha, Seock-Yeon Hwang, Un-Kyu Park, Seok Kyo Seo, Sang-Ho Lee, Min-Sik Jeong, SiHyun Cho, Spandana Rajendra Kopalli, Si-Kwan Kim
Testicular hyperthermia is well studied to cause impaired spermatogenesis. In the present study, the protective effect of enzymatically modified (pectinase-treated) Panax ginseng (GINST) against intermittent sub-chronic heat stress-induced testicular damage in rats was investigated. Male Sprague-Dawley rats were divided into four groups: normal control (NC), heat-stressed control (HC), heat-stressed plus GINST-100 mg/kg/day (HG100) and heat-stressed plus GINST-200 mg/kg/day (HG200) treatment groups. GINST (100 and 200 mg/kg/day) was mixed separately with a regular pellet diet and was administered orally for 8 weeks starting from 1 week before heat exposure...
June 2017: Reproduction: the Official Journal of the Society for the Study of Fertility
https://www.readbyqxmd.com/read/28428318/bottom-up-construction-of-a-superstructure-in-a-porous-uranium-organic-crystal
#4
Peng Li, Nicolaas A Vermeulen, Christos D Malliakas, Diego A Gómez-Gualdrón, Ashlee J Howarth, B Layla Mehdi, Alice Dohnalkova, Nigel D Browning, Michael O'Keeffe, Omar K Farha
Bottom-up construction of highly intricate structures from simple building blocks remains one of the most difficult challenges in chemistry. Here, we report a structurally complex, mesoporous uranium-based metal-organic framework (MOF) made from simple starting components. The structure is comprised of 10 uranium nodes and 7 tricarboxylate ligands (both crystallographically non-equivalent); resulting in a 173.3 angstrom cubic unit cell enclosing 816 uranium nodes and 816 organic linkers-the largest unit cell found for any nonbiological material...
April 20, 2017: Science
https://www.readbyqxmd.com/read/28428020/repeated-sub-chronic-oral-toxicity-study-of-xylooligosaccharides-xos-in-dogs
#5
Yonglin Gao, Yunzhi Wang, Yanshen Li, Rui Han, Chunmei Li, Lin Xiao, Susan Cho, Yukui Ma, Chao Fang, Albert W Lee
In this study, Beagle dogs were administered xylooligosaccharide (XOS, CAS # 87099-0) at doses of 0, 1250, 2500, and 5000 mg/kg/day by oral gavage for 26 weeks. A 4-week recovery period was added to observe delayed or reversible toxicity. Measurements included body weight, food consumption, clinical observations, temperature, electrocardiogram (ECG), urinalysis, blood chemistry, hematology, organ weight, gross necropsy, and histopathological examination. Except for transient diarrhea or vomiting, no treatment-related adverse effects were noted...
April 17, 2017: Regulatory Toxicology and Pharmacology: RTP
https://www.readbyqxmd.com/read/28426208/global-and-local-partitioning-of-the-charge-transferred-in-the-parr-pearson-model
#6
Angel Ulises Orozco-Valencia, José Luis Gázquez, Alberto Vela
Through a simple proposal, the charge transfer obtained from the cornerstone theory of Parr and Pearson is partitioned, for each reactant, in two channels: an electrophilic, through which the species accepts electrons, and the other, a nucleophilic, where the species donates electrons. It is shown that this global model allows us to determine unambiguously the charge transfer mechanism prevailing in a given reaction. The partitioning is extended to include local effects through the Fukui functions of the reactants...
April 20, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28425751/development-of-red-blood-cell-autoantibodies-following-treatment-with-checkpoint-inhibitors-a-new-class-of-anti-neoplastic-immunotherapeutic-agents-associated-with-immune-dysregulation
#7
Laura L Cooling, John Sherbeck, Jonathon C Mowers, Sheri L Hugan
Ipilimumab, nivolumab, and pembrolizumab represent a new class of immunotherapeutic drugs for treating patients with advanced cancer. Known as checkpoint inhibitors, these drugs act to upregulate the cellular and humoral immune response to tumor antigens by inhibiting T-cell autoregulation. As a consequence, they can be associated with immune-related adverse events (irAEs) due to loss of self-tolerance, including rare cases of immune-related cytopenias. We performed a retrospective clinical chart review, including serologic, hematology, and chemistry laboratory results, of two patients who developed red blood cell (RBC) autoantibodies during treatment with a checkpoint inhibitor...
January 2017: Immunohematology
https://www.readbyqxmd.com/read/28425543/in-situ-nuclear-magnetic-resonance-microimaging-of-live-biofilms-in-a-microchannel
#8
R S Renslow, M J Marshall, A E Tucker, W B Chrisler, X-Y Yu
Biofilms are comprised of microbial cells and an extracellular polymeric substance (EPS) matrix that supports interactions between community members and with the local environment. The highly hydrated EPS matrix makes the application of many biofilm visualization techniques difficult. Hence, to better visualize how biofilms interact with their environment, there is a need for imaging techniques to monitor hydrated state biofilm dynamics. We employed an in situ dynamic approach to construct label-free images of biofilms...
April 20, 2017: Analyst
https://www.readbyqxmd.com/read/28425280/large-scale-synthesis-of-monodisperse-uio-66-crystals-with-tunable-sizes-and-missing-linker-defects-via-acid-base-co-modulation
#9
Yajing Zhao, Qing Zhang, Yali Li, Rui Zhang, Guang Lu
Beyond their pore structures and surface chemistry, precise controls over other attributes of metal-organic frameworks (MOFs) such as shapes, sizes, and defects are also favorable to their fundamental studies and applications but still remain challenging. Herein, we reported an acid/base co-modulation strategy to the large-scale synthesis of monodisperse UiO-66 crystals with acetic acid for modulating crystal shape and with triethylamine (TEA) as a base for controlling the nucleation of crystallization and tuning the formation of missing linker defects via promoting presumably the singe deprotonation of terephthalic acid linkers...
April 20, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28424520/decarboxylative-alkenylation
#10
Jacob T Edwards, Rohan R Merchant, Kyle S McClymont, Kyle W Knouse, Tian Qin, Lara R Malins, Benjamin Vokits, Scott A Shaw, Deng-Hui Bao, Fu-Liang Wei, Ting Zhou, Martin D Eastgate, Phil S Baran
Olefin chemistry, through pericyclic reactions, polymerizations, oxidations, or reductions, has an essential role in the manipulation of organic matter. Despite its importance, olefin synthesis still relies largely on chemistry introduced more than three decades ago, with metathesis being the most recent addition. Here we describe a simple method of accessing olefins with any substitution pattern or geometry from one of the most ubiquitous and variegated building blocks of chemistry: alkyl carboxylic acids...
April 19, 2017: Nature
https://www.readbyqxmd.com/read/28422350/electronic-g-tensors-in-u-v-complexes-a-computational-study
#11
Helen Moylan, Joseph McDouall
The theory and computation of EPR parameters from first principles has seen a great deal of development over the past two decades. In particular, various techniques for the computation of the electronic g tensor have been implemented in many quantum chemistry packages. These methods have been successfully applied to paramagnetic organic species and transition metal systems. The situation is less well-understood and established in the case of actinide containing molecules and there is a dearth of experimental data available for validation of computations...
April 19, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28422202/efficient-phosphine-mediated-formal-c-sp-3-c-sp-3-coupling-reactions-of-alkyl-halides-in-batch-and-flow
#12
U P N Tran, K J Hock, C P Gordon, R M Koenigs, T V Nguyen
The construction of C(sp(3))-C(sp(3)) bond is an essential chemical transformation in synthetic chemistry due to its abundance in organic scaffolds. Here we demonstrate a valuable adaptation of the Wittig-type chemical procedure to efficiently facilitate C(sp(3))-C(sp(3)) bond formation utilizing a range of alkyl building blocks. Additionally the method is amenable with flow synthesis to afford coupled products in good to excellent yields without laborious purification process.
April 19, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28421741/uphill-water-transport-on-a-wettability-patterned-surface-experimental-and-theoretical-results
#13
Yuji Hirai, Hiroyuki Mayama, Yasutaka Matsuo, Masatsugu Shimomura
In nature, there exist a number of functional water-controlling surfaces, such as the water-repellent surface of lotus leaves, the superhydrophobic water-adhesive surface of rose petals, the water-harvesting surface of a beetle's back, and the water-transporting surface of the legs of Ligia exotica. These natural surfaces suggest that surface chemistry and hierarchical structures are essential for controlling water behavior. We have reported the preparation of superhydrophobic and anti-reflection silicon nanospike-array structures using self-organized honeycomb-patterned films as 3D dry etching masks...
April 19, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28419173/sponge-symbioses-between-xestospongia-deweerdtae-and-plakortis-spp-are-not-motivated-by-shared-chemical-defense-against-predators
#14
Micah Jaarsma Marty, Jan Vicente, Benjamin L Oyler, Allen Place, Russell T Hill
The recently described epizoic sponge-sponge symbioses between Xestospongia deweerdtae and two species of Plakortis present an unusual series of sponge interactions. Sponges from the genus Plakortis are fierce allelopathic competitors, rich in cytotoxic secondary metabolites, and yet X. deweerdtae flourishes as an epizoic encrustation on Plakortis deweerdtaephila and Plakortis symbiotica. Our objective in this study was to evaluate the hypothesis that X. deweerdtae grows epizoic to these two species of Plakortis due to a shared chemical defense against predators...
2017: PloS One
https://www.readbyqxmd.com/read/28419100/validation-of-two-multiplex-platforms-to-quantify-circulating-markers-of-inflammation-and-endothelial-injury-in-severe-infection
#15
Aleksandra Leligdowicz, Andrea L Conroy, Michael Hawkes, Kathleen Zhong, Gerald Lebovic, Michael A Matthay, Kevin C Kain
Biomarkers can prognosticate outcome and enable risk-stratification. In severe infection, focusing on multiple markers reflecting pathophysiological mechanisms of organ injury could enhance management and pathway-directed therapeutics. Limited data exist on the performance of multiplex biomarker platforms. Our goal was to compare endothelial and immune activation biomarkers in severe pediatric infections using two multiplex platforms. Frozen plasma from 410 children presenting to the Jinja Regional Hospital in Uganda with suspected infection was used to measure biomarkers of endothelial (Angiopoietin-2, sFlt-1, sVCAM-1, sICAM-1) and immune (IL-6, IP-10, sTNFR-1, CHI3L1) activation...
2017: PloS One
https://www.readbyqxmd.com/read/28418703/radioresistance-of-adenine-to-cosmic-rays
#16
Gabriel S Vignoli Muniz, Christian F Mejía, Rafael Martinez, Basile Auge, Hermann Rothard, Alicja Domaracka, Philippe Boduch
The presence of nucleobases in carbonaceous meteorites on Earth is an indication of the existence of this class of molecules in outer space. However, space is permeated by ionizing radiation, which can have damaging effects on these molecules. Adenine is a purine nucleobase that amalgamates important biomolecules such as DNA, RNA, and ATP. Adenine has a unique importance in biochemistry and therefore life. The aim of this work was to study the effects of cosmic ray analogues on solid adenine and estimate its survival when exposed to corpuscular radiation...
April 2017: Astrobiology
https://www.readbyqxmd.com/read/28416275/cisplatin-analogs-confer-protection-against-cyanide-poisoning
#17
Anjali K Nath, Xu Shi, Devin L Harrison, Jordan E Morningstar, Sari Mahon, Adriano Chan, Patrick Sips, Jangwoen Lee, Calum A MacRae, Gerry R Boss, Matthew Brenner, Robert E Gerszten, Randall T Peterson
Cisplatin holds an illustrious position in the history of chemistry most notably for its role in the virtual cure of testicular cancer. Here we describe a role for this small molecule in cyanide detoxification in vivo. Cyanide kills organisms as diverse as insects, fish, and humans within seconds to hours. Current antidotes exhibit limited efficacy and are not amenable to mass distribution requiring the development of new classes of antidotes. The binding affinity of the cyanide anion for the positively charged metal platinum is known to create an extremely stable complex in vitro...
April 7, 2017: Cell Chemical Biology
https://www.readbyqxmd.com/read/28414388/infrared-spectroscopy-of-secondary-organic-aerosol-precursors-and-investigation-of-the-hygroscopicity-of-soa-formed-from-the-oh-reaction-with-guaiacol-and-syringol
#18
Waed Ahmad, Cecile Coeur, Alexandre Tomas, Thomas Fagniez, Jean-Blaise Brubach, Arnaud Cuisset
Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) synchrotron analyses supplemented by density functional theory (DFT) anharmonic calculations have been undertaken to study the fundamental vibrational signatures of guaiacol and syringol, two methoxyphenol compounds found at the highest concentrations in fresh wood smoke and precursors of secondary organic aerosols (SOA) affecting the radiative balance and chemistry of the atmosphere. Nitroderivatives of these two compounds have also been studied experimentally for nitroguaiacol and theoretically for nitrosyringol...
April 10, 2017: Applied Optics
https://www.readbyqxmd.com/read/28414232/application-of-deep-eutectic-solvents-des-for-phenolic-compounds-extraction-overview-challenges-and-opportunities
#19
Mariana Ruesgas-Ramon, Maria Cruz Figueroa-Espinoza, Erwann Durand
The green chemistry era has pushed the scientific community to investigate and implement new solvents in the phenolic compounds (PC) extraction, as alternative to the organic solvents which are toxic and may be dangerous. Recently, Deep Eutectic Solvents (DES) have been applied as extraction solvents of PC. They have the advantages to be biodegradable, easy to handle with very low toxicity. Nevertheless, the extraction process is affected by several factors: affinity between DES and the target compounds, the water content, the molar ratio between DES' starting molecules, the liquid:solid ratio between the DES and sample, and the conditions and extraction method...
April 17, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28413749/targeted-fluoro-positioning-for-the-discovery-of-a-potent-and-highly-selective-matrix-metalloproteinase-inhibitor
#20
Thomas Fischer, Rainer Riedl
The incorporation of fluorine atoms into functional molecules is of wide interest in synthetic organic chemistry as well as cognate disciplines. In particular, in medicinal chemistry, there is a strong desire to positively influence the physicochemical molecular properties of drug compounds by introducing fluorine into biologically active molecules. Here, we present targeted fluoro positioning as the key design principle of converting a weak matrix metalloproteinase-13 (MMP-13) inhibitor into a very potent (IC50=6 nm) and highly selective (selectivity factors of >1000 over MMP-1, 2, 3, 7, 8, 9, 10, 12, 14) inhibitor with excellent plasma and microsomal stability, and no binding to the hERG channel (hERG: human ether-a-go-go related gene)...
April 2017: ChemistryOpen
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