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Carbon dating

Nataliya F Lazareva, Viktor P Baryshok, Igor M Lazarev
The plant pentacyclic alkaloid camptothecin and its structural analogs were extensively studied. These compounds are interesting due to the antitumor activity associated with their ability to inhibit topoisomerase I in tumor cells. During the last decades of the 20th century, a large number of the silicon-containing camptothecins (silatecans) were synthesized. 7-tert-Butyldimethylsilyl-10-hydroxy-camptothecin (DB-67 or AR-67) has enhanced lipophilicity and demonstrates a antitumor activity superior to its carbon analog...
December 14, 2017: Archiv der Pharmazie
Kin-Ya Tomizaki, Yuichi Yamaguchi, Naoyuki Tsukamoto, Takahito Imai
Gold nanoparticles are promising nanomaterials for catalytic reactions, sensing/imaging systems, photonic/plasmonic devices, and electronics because of their unique physical and chemical properties. To date, significant catalytic activities of gold nanoparticles have been reported for reactions such as carbon monooxide oxidation and 4-nitrophenol reduction, and diverse gold nanoparticle morphologies such as nanospheres, wires, rods, and cubes have been achieved using a variety of capping/stabilizing organic molecules...
December 13, 2017: Protein and Peptide Letters
Sarah L Zieger, Silke Ammerschubert, Andrea Polle, Stefan Scheu
Evidence is increasing that soil animal food webs are fueled by root-derived carbon (C) and also by root-derived nitrogen (N). Functioning as link between the above- and belowground system, trees and their species identity are important drivers structuring soil animal communities. A pulse labeling experiment using 15N and 13C was conducted by exposing beech (Fagus sylvatica) and ash (Fraxinus excelsior) seedlings to 13CO2 enriched atmosphere and tree leaves to 15N ammonium chloride solution in a plant growth chamber under controlled conditions for 72 h...
2017: PloS One
Vera M Hesslinger, Claus-Christian Carbon, Heiko Hecht
The mere presence of a depiction of eyes can elicit a sense of being watched in the perceiver. To this date, the factors affecting the intensity of this sense of being watched, however, have not been investigated. In the present experiment, we tested the impact of two potentially relevant variables: arousal (manipulated using specific musical pieces) and duration of the perceptual episode (manipulated using presentation times of 200 ms and 10 s, respectively). We asked participants to report how intensely they felt being watched while we exposed them to various observation cues ranging from human eyes to surveillance cameras...
November 2017: I-Perception
Kevin M Cannon, Stephen W Parman, John F Mustard
On Mars, clay minerals are widespread in terrains that date back to the Noachian period (4.1 billion to 3.7 billion years ago). It is thought that the Martian basaltic crust reacted with liquid water during this time to form hydrated clay minerals. Here we propose, however, that a substantial proportion of these clays was formed when Mars' primary crust reacted with a dense steam or supercritical atmosphere of water and carbon dioxide that was outgassed during magma ocean cooling. We present experimental evidence that shows rapid clay formation under conditions that would have been present at the base of such an atmosphere and also deeper in the porous crust...
December 6, 2017: Nature
Maryam Delavarrafiee, H Christopher Frey
Flex Fuel Vehicles (FFVs) typically operate on gasoline or E85, an 85%/15% volume blend of ethanol and gasoline, E85. Differences in FFV fuel use and tailpipe emission rates are quantified for E85 versus gasoline based on real-world measurements of five FFVs with a portable emissions measurement system (PEMS), supplemented chassis dynamometer data and estimates from the MOtor Vehicle Emission Simulator (MOVES) model. Because of inter-vehicle variability, an individual FFV may have higher nitrogen oxides (NOx) or carbon monoxide (CO) emission rates on E85 versus gasoline, even though average rates are lower...
December 7, 2017: Journal of the Air & Waste Management Association
Jonas Steinhauser, Patrick Wespi, Grzegorz Kwiatkowski, Sebastian Kozerke
Isoflurane is a frequently used anesthetic in small-animal dissolution dynamic nuclear polarization-magnetic resonance imaging (DNP-MRI) studies. Although the literature suggests interactions with mitochondrial metabolism, the influence of the compound on cardiac metabolism has not been assessed systematically to date. In the present study, the impact of low versus high isoflurane concentration was examined in a crossover experiment in healthy rats. The results revealed that cardiac metabolism is modulated by isoflurane concentration, showing increased [1-13 C]lactate and reduced [13 C]bicarbonate production during high isoflurane relative to low isoflurane dose [average differences: +16% [1-13 C]lactate/total myocardial carbon, -22% [13 C]bicarbonate/total myocardial carbon; +51% [1-13 C]lactate/[13 C]bicarbonate]...
December 5, 2017: NMR in Biomedicine
Shinya Suzuki, Florian Part, Yasushi Matsufuji, Marion Huber-Humer
To date construction materials that contain engineered nanomaterials (ENMs) are available at the markets, but at the same time very little is known about their environmental fate. Therefore, this study aimed at modeling the potential fate of ENMs by using the example of the Japanese construction sector and by conducting a dynamic material flow analysis. Expert interviews and national reports revealed that about 3920-4660 tons of ENMs are annually used for construction materials in Japan. Nanoscale TiO2, SiO2, Al2O3 and carbon black have already been applied for decades to wall paints, road markings or concrete...
November 28, 2017: Waste Management
Joshua R Elmore, Anna Furches, Gara N Wolff, Kent Gorday, Adam M Guss
Pseudomonas putida strains are highly robust bacteria known for their ability to efficiently utilize a variety of carbon sources, including aliphatic and aromatic hydrocarbons. Recently, P. putida has been engineered to valorize the lignin stream of a lignocellulosic biomass pretreatment process. Nonetheless, when compared to platform organisms such as Escherichia coli, the toolkit for engineering P. putida is underdeveloped. Heterologous gene expression in particular is problematic. Plasmid instability and copy number variance provide challenges for replicative plasmids, while use of homologous recombination for insertion of DNA into the chromosome is slow and laborious...
December 2017: Metabolic Engineering Communications
Israel A Figueroa, Tyler P Barnum, Pranav Y Somasekhar, Charlotte I Carlström, Anna L Engelbrektson, John D Coates
Dissimilatory phosphite oxidation (DPO), a microbial metabolism by which phosphite (HPO32-) is oxidized to phosphate (PO43-), is the most energetically favorable chemotrophic electron-donating process known. Only one DPO organism has been described to date, and little is known about the environmental relevance of this metabolism. In this study, we used 16S rRNA gene community analysis and genome-resolved metagenomics to characterize anaerobic wastewater treatment sludge enrichments performing DPO coupled to CO2 reduction...
November 28, 2017: Proceedings of the National Academy of Sciences of the United States of America
Daniel L Gall, Wayne S Kontur, Wu Lan, Hoon Kim, Yanding Li, John Ralph, Timothy J Donohue, Daniel R Noguera
New environmentally sound technologies are needed to derive valuable compounds from renewable resources. Lignin, an abundant polymer in terrestrial plants comprised predominantly of guaiacyl and syringyl monoaromatic phenylpropanoid units, is a potential natural source of aromatic compounds. In addition, the plant secondary metabolite, tricin, is a recently discovered and moderately abundant flavonoid in grasses. The most prevalent inter-unit linkage between guaiacyl, syringyl, and tricin units is the β-ether linkage...
November 27, 2017: Applied and Environmental Microbiology
Consolazione Caruso, Carmen Rizzo, Santina Mangano, Annarita Poli, Paola Di Donato, Ilaria Finore, Barbara Nicolaus, Gaetano Di Marco, Luigi Michaud, Angelina Lo Giudice
Four sponge-associated Antarctic bacteria (i.e. Winogradskyella spp. CAL384 and CAL396, Colwellia sp. GW185 and Shewanella sp. CAL606) were selected for the highly mucous appearance of their colonies on agar plates. The production of extracellular polymeric substances (EPSs) was enhanced by a step-by step approach varying the carbon source, substrate and NaCl concentrations, temperature and pH. The EPSs produced under optimal conditions were chemically characterized, resulting in a moderate carbohydrate content (range 15-28%), and the presence of proteins (range 3-24%) and uronic acids (range 3...
November 27, 2017: Applied and Environmental Microbiology
Xiang Miao, Dan Qu, Dongxue Yang, Bing Nie, Yikang Zhao, Hongyou Fan, Zaicheng Sun
Multiple-color-emissive carbon dots (CDots) have potential applications in various fields such as bioimaging, light-emitting devices, and photocatalysis. The majority of the current CDots to date exhibit excitation-wavelength-dependent emissions with their maximum emission limited at the blue-light region. Here, a synthesis of multiple-color-emission CDots by controlled graphitization and surface function is reported. The CDots are synthesized through controlled thermal pyrolysis of citric acid and urea. By regulating the thermal-pyrolysis temperature and ratio of reactants, the maximum emission of the resulting CDots gradually shifts from blue to red light, covering the entire light spectrum...
November 27, 2017: Advanced Materials
Mary H Abernathy, Jingjie Yu, Fangfang Ma, Michelle Liberton, Justin Ungerer, Whitney D Hollinshead, Saratram Gopalakrishnan, Lian He, Costas D Maranas, Himadri B Pakrasi, Doug K Allen, Yinjie J Tang
Background: Synechococcus elongatus UTEX 2973 is the fastest growing cyanobacterium characterized to date. Its genome was found to be 99.8% identical to S. elongatus 7942 yet it grows twice as fast. Current genome-to-phenome mapping is still poorly performed for non-model organisms. Even for species with identical genomes, cell phenotypes can be strikingly different. To understand Synechococcus 2973's fast-growth phenotype and its metabolic features advantageous to photo-biorefineries, 13C isotopically nonstationary metabolic flux analysis (INST-MFA), biomass compositional analysis, gene knockouts, and metabolite profiling were performed on both strains under various growth conditions...
2017: Biotechnology for Biofuels
Bakheet Elsadek, El-Sayed El-Sayed, Ahmed Mansour, Ayman Elazab
Ajwa, a variety of date palme Phoenix dactylifera L., has long been used and considered as one of the most popular fruits in the North Africa and Middle East region. For Muslims this fruit is of religious importance and is mentioned several times in Quran. Besides being a part of the Arabian essential diet, dates have been used traditionally for number of complications. This study aimed to evaluate the possible potential of Ajwa date extract to guard against carbon tetrachloride (CCL4)-induced liver damage in rats...
November 2017: Pakistan Journal of Pharmaceutical Sciences
Sarah E Keithley, Mary Jo Kirisits
Extracellular polymeric substances (EPS) are an important parameter in drinking-water biofilters, and, to date, this is the first study to compare protocols from the literature for extracting EPS from granular filter media. Five extraction protocols were compared, and one was improved by varying the type of initial physical treatment and the shaking intensity, temperature, and time of incubation. Extracting EPS from granular filter media in triplicate by combining 2 g (wet weight) of filter media with 10 mL of extraction buffer (10 mM Tris, 10 mM EDTA, 2...
November 8, 2017: Water Research
Weiqing Mao, Li Xiang, Laurent Maron, Xuebing Leng, Yaofeng Chen
The first phosphoniomethylidene complexes of scandium and lutetium, [LLn(CHPPh3)X] (L = [MeC(NDIPP)CHC(NDIPP)Me]-; Ln = Sc, X = Me, I, TfO; Ln = Lu, X = CH2SiMe3), have been synthesized and fully characterized. DFT calculations clearly demonstrate the presence of an allylic Ln, C, P π-type interaction in these complexes. X-ray diffraction indicates that the scandium iodide complex has the shortest ScC bond length to date (2.044(5) Å). These phosphoniomethylidene complexes readily convert into the ylide complexes, and the reactivity is affected by both X- anion and Ln3+ ion...
November 27, 2017: Journal of the American Chemical Society
Zhenzhen Du, Chengkun Guo, Linjun Wang, Ajuan Hu, Song Jin, Taiming Zhang, Hongchang Jin, Zhikai Qi, Sen Xin, Xianghua Kong, Yu-Guo Guo, Hengxing Ji, Li-Jun Wan
Lithium-sulfur batteries are widely seen as a promising next-generation energy storage system owing to their ultrahigh energy density. Though extensive research effort tackles poor cycling performance and self-discharge, battery stability has been improved at the expense of energy density. We have developed an interlayer consisting of 2-layer CVD-grown graphene supported by a conventional polypropylene (PP) separator. Unlike interlayers made of discrete nano/micro-structures that increase the thickness and weight of the separator, the CVD-graphene is an intact film with area of 5 × 60 cm2 and has a thickness of ∼0...
November 27, 2017: ACS Applied Materials & Interfaces
Joo-Hyung Kim, Young Hwa Jung, Jong Hyuk Yun, P Ragupathy, Do Kyung Kim
To date, the possible depletion of lithium resources has become relevant, giving rise to the interest in Na-ion batteries (NIBs) as promising alternatives to Li-ion batteries. While extensive investigations have examined various transition metal oxides and chalcogenides as anode materials for NIBs, few of these have been able to utilize their high specific capacity in sodium-based systems because of their irreversibility in a charge/discharge process. Here, the mixed Sn-S nanocomposites uniformly distributed on reduced graphene oxide are prepared via a facile hydrothermal synthesis and a unique carbothermal reduction process, producing ultrafine nanoparticle with the size of 2 nm...
November 24, 2017: Small
Krzysztof Sieja, Jarosław von Mach-Szczypiński, Joanna von Mach-Szczypiński
Many women are exposed to carbon disulfide (CS<sub>2</sub>) hazards at work every day. Working with CS<sub>2</sub> may cause some women to experience abnormalities in their reproductive health. Until now obtained data is generally concentrated on the health effects of CS<sub>2</sub> observed in the viscose industry. To date, CS<sub>2</sub> has not been studied precisely for its potential to have damaging effects on female reproductive system, especially the frequency of menstrual disturbances and the course of menopause...
November 23, 2017: Medycyna Pracy
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