7,477 results match your criteria highly polar


Geographical and Seasonal Thermal Sensitivity of Grazing Pressure by Microzooplankton in Contrasting Marine Ecosystems.

Front Microbiol 2021 5;12:679863. Epub 2021 Jul 5.

Centro de Investigación Mariña, Universidade de Vigo, Vigo, Spain.

Grazing pressure, estimated as the ratio between microzooplankton grazing and phytoplankton growth rates (:μ), is a strong determinant of microbial food-web structure and element cycling in the upper ocean. It is generally accepted that is more sensitive to temperature than μ, but it remains unknown how the thermal dependence (activation energy, ) of :μ varies over spatial and temporal scales. To tackle this uncertainty, we used an extensive literature analysis obtaining 751 paired rate estimates of μ and from dilution experiments performed throughout the world's marine environments. Read More

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Photoinduced 1,2-dicarbofunctionalization of alkenes with organotrifluoroborate nucleophiles radical/polar crossover.

Chem Sci 2021 Jul 7;12(26):9189-9195. Epub 2021 Jun 7.

Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia Pennsylvania 19104-6323 USA

Alkene 1,2-dicarbofunctionalizations are highly sought-after transformations as they enable a rapid increase of molecular complexity in one synthetic step. Traditionally, these conjunctive couplings proceed through the intermediacy of alkylmetal species susceptible to deleterious pathways including β-hydride elimination and protodemetalation. Herein, an intermolecular 1,2-dicarbofunctionalization using alkyl -(acyloxy)phthalimide redox-active esters as radical progenitors and organotrifluoroborates as carbon-centered nucleophiles is reported. Read More

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Configurable topological phonon polaritons in twisted hBN metasurfaces.

Appl Opt 2021 Jul;60(19):5735-5741

Phonon polaritons are hybrid excitations that originate from coupling of photons with optical phonons in polar crystals. Hexagonal boron nitride (hBN) is a representative phonon polariton material in mid-infrared that exhibits long lifetimes and ultraslow propagation. However, due to in-plane isotropic permittivities, the dispersion engineering and highly canalized ray-like propagation along the in-plane surface required in photonic and optoelectronic applications cannot be realized in a bare hBN structure. Read More

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High-Performance Water Harvester Framework for Triphasic and Synchronous Detection of Assorted Organotoxins with Site-Memory-Reliant Security Encryption via pH-Triggered Fluoroswitching.

ACS Appl Mater Interfaces 2021 Jul 13. Epub 2021 Jul 13.

Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.

Atmospheric water harvesting, triphasic detection of water contaminants, and advanced antiforgery measures are among important global agendas, where metal-organic frameworks (MOFs), as an incipient class of multifaceted materials, can affect substantial development of individual properties at the interface of tailor-made fabrication. The chemically robust and microporous MOF, encompassing contrasting pore functionalization, exhibits an S-shaped water adsorption curve at 300 K with a steep pore-filling step near / = 0.5 and shows reversible uptake-release performance. Read More

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Improved real-time segmentation of Intravascular Ultrasound images using coordinate-aware fully convolutional networks.

Comput Med Imaging Graph 2021 Jul 7;91:101955. Epub 2021 Jul 7.

Department of Mechanical and Aerospace Engineering, Monash University, Melbourne, Australia. Electronic address:

Segmentation of Intravascular Ultrasound (IVUS) images into Lumen and Media (interior and exterior) artery vessel walls is highly clinically relevant in the diagnosis and treatment of cardiovascular diseases such as atherosclerosis. When fused with position data, such segmentations also play a key role in reconstructing 3D representations of arteries. Automated segmentation in real-time is known to be a difficult image analysis problem, primarily due to artefacts commonly present in IVUS ultrasound images such as shadows, guide-wire effects, and side-branches. Read More

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Periodic Polarization Waves in a Strained, Highly Polar Ultrathin SrTiO.

Nano Lett 2021 Jul 12. Epub 2021 Jul 12.

Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, 110016 Shenyang, China.

SrTiO is generally paraelectric with centrosymmetric structure exhibiting unique quantum fluctuation related ferroelectricity. Here we reveal highly polar and periodic polarization waves in SrTiO at room temperature, which is stabilized by periodic tensile strains in a sandwiched PbTiO/SrTiO/PbTiO structure. Scanning transmission electron microscopy reveals that periodic / domain structures in PbTiO layers exert unique periodic tensile strains in the ultrathin SrTiO layer and consequently make the highly polar and periodic states of SrTiO. Read More

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Sake (Rice Wine) Brewing Hydrolyzes Highly Polar Sphingolipids to Ceramides and Increases Free Sphingoid Bases.

J Oleo Sci 2021 Jul 9. Epub 2021 Jul 9.

Food and Biotechnology Platform Promoting Project, New Industry Creation Hatchery Center (NICHe), Tohoku University.

In plants and fungi, sphingolipids, characterized by the presence of a sphingoid base (SB), comprise neutral classes, including ceramide (Cer) and glucosylceramide (GlcCer), and acidic classes, including glycosyl inositol phosphoryl ceramide (GIPC). The major class of plant and fungal sphingolipids is GIPC; however, owing to their complicated extraction and analysis, there is still little information regarding the food characteristics of GIPC compounds. In the present study, we evaluated the content and SB composition of highly polar sphingolipids (HPS) in materials that had been obtained from our previous food processing study for GlcCer and Cer. Read More

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Retention dependences support highly confident identification of lipid species in human plasma by reversed-phase UHPLC/MS.

Anal Bioanal Chem 2021 Jul 9. Epub 2021 Jul 9.

Faculty of Chemical Technology, Department of Analytical Chemistry, University of Pardubice, Studentská 573, 53210, Pardubice, Czech Republic.

Reversed-phase ultrahigh-performance liquid chromatography-mass spectrometry (RP-UHPLC/MS) method was developed with the aim to unambiguously identify a large number of lipid species from multiple lipid classes in human plasma. The optimized RP-UHPLC/MS method employed the C18 column with sub-2-μm particles with the total run time of 25 min. The chromatographic resolution was investigated with 42 standards from 18 lipid classes. Read More

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Acoustic metrics to assess humpback whale song unit structure from the Atlantic sector of the Southern ocean.

J Acoust Soc Am 2021 Jun;149(6):4649

Alfred Wegener Institute for Polar and Marine Research, Klußmannstraße 3d, 27570 Bremerhaven, Germany.

Acoustic metrics (AMs) aggregate the acoustic information of a complex signal into a unique number, assisting our interpretation of acoustic environments and providing a rapid and intuitive solution to analyze large passive acoustic datasets. Manual identification and characterization of intraspecific call trait variation has been largely used in a variety of sonic taxa. However, it is time consuming, relatively subjective, and measurements can suffer from low replicability. Read More

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Enhancing the efficiency of semiconducting quantum dot photocatalyzed atom transfer radical polymerization by ligand shell engineering.

J Chem Phys 2021 May;154(20):204903

Department of Materials Science and Nanoengineering, Rice University, Houston, Texas 77005, USA.

Manipulating the ligand shell of semiconducting quantum dots (QDs) has proven to be a promising strategy to enhance their photocatalytic performance for small molecule transformations, such as H evolution and CO reduction. However, ligand-controlled catalysis for macromolecules, which differ from small molecules in penetrability and charge transfer behavior due to their bulky sizes, still remains undiscovered. Here, we systematically investigate the role of surface ligands in the photocatalytic performance of cadmium selenide (CdSe) QDs in light-induced atom transfer radical polymerization (ATRP) by using thiol-based ligands with various polarities and chain lengths. Read More

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Ethylene/ethane separation in a stable hydrogen-bonded organic framework through a gating mechanism.

Nat Chem 2021 Jul 8. Epub 2021 Jul 8.

Department of Chemistry, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX, United States.

Porous materials are very promising for the development of cost- and energy-efficient separation processes, such as for the purification of ethylene from ethylene/ethane mixture-an important but currently challenging industrial process. Here we report a microporous hydrogen-bonded organic framework that takes up ethylene with very good selectivity over ethane through a gating mechanism. The material consists of tetracyano-bicarbazole building blocks held together through intermolecular CN···H-C hydrogen bonding interactions, and forms as a threefold-interpenetrated framework with pores of suitable size for the selective capture of ethylene. Read More

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Bio-based and compostable polyesters in food contact: analysis of monomers and (in)organic fillers.

Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2021 Jul 8:1-17. Epub 2021 Jul 8.

Chair for Food Chemistry and Food and Skin Contact Materials, Technische Universität Dresden, Dresden, Germany.

Polyesters labelled as bio-based or compostable are increasingly common among the 'bioplastics' in use as food contact materials (FCM). The knowledge of material composition is mandatory to predict potential leachable oligomers as well as to partly evaluate the correctness of the label 'bioplastic', which is used for promotional purposes. The composition of (bio)polyesters can be determined by alkaline hydrolysis of the entire material and subsequent analysis of the monomers via high-performance liquid chromatography with diode array detection and GC-MS detection. Read More

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Synthesis of Nonalternating Polyketones Using Cationic Diphosphazane Monoxide-Palladium Complexes.

J Am Chem Soc 2021 Jul 8;143(28):10743-10750. Epub 2021 Jul 8.

State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China.

Copolymerization of olefin with carbon monoxide has received considerable interest from both academia and industry, and the introduction of polar carbonyl group renders the resultant polyketones with excellent mechanical strength, crystallinity, photodegradability, hydrophilicity, surface, and barrier properties. However, most of the reported polyketones are difficult to be processed because of limited solubility in common solvents and high melting temperature ( ∼ 260 °C) resulting from the strictly alternative structure. Nonalternating copolymerization of ethylene with CO is a very promising method to circumvent the problem of processability of traditional perfectly alternating polyketone. Read More

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The Aryne-Abramov Reaction as a 1,2-Benzdiyne Platform for the Generation and Solvent-Dependent Trapping of 3-Phosphonyl Benzynes.

J Org Chem 2021 Jul 8. Epub 2021 Jul 8.

Chemistry Department, Ripon College, 300 West Seward Street, Ripon, Wisconsin 54971, United States.

Synthetic methodology utilizing two aryne intermediates (i.e., a formal benzdiyne) enables the rapid generation of structurally complex molecules with diverse functionality. Read More

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Dearomatization through Photoredox Hydroarylation: Discovery of a Radical-Polar Crossover Strategy.

Org Lett 2021 Jul 7;23(14):5576-5580. Epub 2021 Jul 7.

Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States.

Indole dearomatization has been achieved via radical hydroarylation. Under mild photoredox conditions, a range of indole derivatives undergo hydroarylation to form 2-arylindoline products. Mechanistically, radical termination occurs primarily via stepwise reduction/protonation, with a small contribution from concerted hydrogen atom transfer. Read More

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Efficient Gas and VOC Separation and Pesticide Detection in a Highly Stable Interpenetrated Indium-Organic Framework.

Inorg Chem 2021 Jul 7;60(14):10698-10706. Epub 2021 Jul 7.

Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, National Demonstration Center for Experimental Chemistry Education (Northwest University), College of Chemistry & Materials Science, Northwest University. Xi'an, 710069, People's Republic of China.

The new indium-based organic framework {(MeNH)[In(BDPO)]·DMF·2HO} () was successfully constructed by using the oxalamide group modified ligand ,'-bis(isophthalic acid)oxalamide (HBDPO). This framework presents a 2-fold interpenetrating structural characteristic, and the unique polar pore environment leads to a high capture ability for CO, CH and CHOH and good separation ability for CO and CH over CH as well as for CHOH over CHOH, which was further verified by an ideal adsorbed solution theory (IAST) calculation. Theoretical simulations pointed out the possible adsorption sites of different adsorbed gases in . Read More

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A comprehensive study on the performance of different retention mechanisms in sport drug testing by liquid chromatography tandem mass spectrometry.

J Chromatogr B Analyt Technol Biomed Life Sci 2021 Jun 3;1178:122821. Epub 2021 Jun 3.

Department of Analytical Chemistry, Institute of Fine Chemistry and Nanochemistry, Marie Curie Building (Annex), Campus of Rabanales, University of Córdoba, 14071 Córdoba, Spain.

Anti-doping substances listed by the World Anti-Doping Agency (WADA) include hundreds of compounds of very different physico-chemical properties. Anti-doping control laboratories need to screen all these substances in the so-called Initial Testing Procedures (ITPs) what is very challenging from an analytical point of view. ITPs are mostly based on reversed-phase (RP) liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) using C18 columns, which feature poor retention and peak tailing for polar and basic compounds, respectively. Read More

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[Simultaneous determination of three quaternary ammonium muscle relaxants in blood by high performance liquid chromatography-tandem mass spectrometry].

Se Pu 2021 Jul;39(7):695-701

State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China.

Vecuronium, rocuronium, and pancuronium are widely used as non-depolarizing muscle relaxants. There have been occasional cases of allergic reactions and even death when using such muscle relaxants. Rapid determination of the concentration of these muscle relaxants in blood can provide valuable information for early clinical diagnosis. Read More

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[Ensemble hologram quantitative structure activity relationship model of the chromatographic retention index of aldehydes and ketones].

Se Pu 2021 Mar;39(3):331-337

College of Chemistry and Chemical Engineering, Xi'an Shiyou University, Xi'an 710065, China.

Chromatographic retention index (RI) is an important parameter for describing the retention behavior of substances in chromatographic analysis. Experimentally determining the RI values of different aldehyde and ketone compounds in all kinds of polar stationary phases is expensive and time consuming. Quantitative structure activity relationship (QSAR) is an important chemometric technique that has been widely used to correlate the properties of chemicals to their molecular structures. Read More

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[Research progress of microextraction by packed sorbent and its application in microvolume sample extraction].

Se Pu 2021 Mar;39(3):219-228

State key Laboratory of Nuclear, Biological and Chemical Protection for Civilian, Beijing 102205, China.

Microextraction is a rapidly developing sample preparation technology in the field of analytical chemistry, which is seeing widespread application. Accurate sample preparation can not only save time but also improve the efficiency of analysis, determination, and data quality. At present, sample pretreatment methods must be rapid, allow for miniaturization, automation, and convenient online connection with analytical instruments. Read More

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Integration of biosorption and biodegradation in a fed-batch mode for the enhanced crude oil remediation.

Authors:
S Sharma L M Pandey

Lett Appl Microbiol 2021 Jul 5. Epub 2021 Jul 5.

Bio-interface & Environmental Engineering Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Assam, India.

Microbial bioremediation of oil-contaminated sites is still a challenge due to the slower rate and susceptibility of microbes to a higher concentration of oil. The poor bioavailability, hydrophobicity, and non-polar nature of oil slow down microbial biodegradation. In this study, biodegradation of crude oil is performed in fed-batch mode using an oil-degrader Pseudomonas aeruginosa to address the issue of substrate toxicity. Read More

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Disproportionate microbial responses to decadal drainage on a Siberian floodplain.

Glob Chang Biol 2021 Jul 3. Epub 2021 Jul 3.

Korea Polar Research Institute, Incheon, Republic of Korea.

Permafrost thaw induces soil hydrological changes which in turn affects carbon cycle processes in the Arctic terrestrial ecosystems. However, hydrological impacts of thawing permafrost on microbial processes and greenhouse gas (GHG) dynamics are poorly understood. This study examined changes in microbial communities using gene and genome-centric metagenomics on an Arctic floodplain subject to decadal drainage, and linked them to CO and CH flux and soil chemistry. Read More

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[Analysis of metabolomics and proteomics based on capillary electrophoresis-mass spectrometry].

Se Pu 2020 Sep;38(9):1013-1021

Institute of Biomedical Materials and Engineering, College of Chemistry and Chemical Engineering, Affiliated Hospital of Qingdao University, Qingdao University, Qingdao 266071, China.

Capillary electrophoresis-mass spectrometry (CE-MS) has the advantages of higher sensitivity, higher efficiency, and less sample consumption. Moreover, it possesses obvious advantages during the analysis of strongly charged and highly polar samples. CE-MS has been widely applied in life sciences, medicine, and pharmacology. Read More

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September 2020

[Determination of streptomycin and dihydrostreptomycin in grapes by liquid chromatography-tandem mass spectrometry].

Se Pu 2020 Dec;38(12):1396-1401

Institute of Quality and Standard of Agro-Products, Zhejiang Academy of Agricultural Sciences, State Key Laboratory for Managing Biotic and Chemical Theats to the Quality and Safety of Agro-Products, Hangzhou 310021, China.

Streptomycin (STR) and dihydrostreptomycin (DSTR) are two of the most common aminoglycoside antibiotics used in veterinary medicine. STR is produced by some strains, and DSTR is a derivative of STR. In recent years, STR has been widely used in grapes to induce denuclearization. Read More

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December 2020

[Preparation of a versatile polyethylene glycol-bonded stationary phase based on silica monolith particles and its application in multi-modal separation in high performance liquid chromatography].

Se Pu 2020 Aug;38(8):937-944

College of Science, University of Shanghai for Science and Technology, Shanghai 200093, China.

Silica monolith particles with sizes of 2-5 μm and pore sizes of 20-60 nm were obtained by grinding, flotation, pseudomorphic transformation, and hydrothermal treatment of the silica monolith prepared by the sol-gel method. The pseudomorphic transformation was performed with a dual micellar templating system consisting of Capstone FS-66, a partially fluorinated anion surfactant, and cetyltrimethylammonium bromide (CTAB), a commonly used cation surfactant. Hydrothermal treatment with a sodium carbonate solution was adopted to further expand the pore size. Read More

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Subcritical Water Extraction of Natural Products.

Molecules 2021 Jun 30;26(13). Epub 2021 Jun 30.

Department of Chemistry, East Carolina University, Greenville, NC 27858, USA.

Subcritical water refers to high-temperature and high-pressure water. A unique and useful characteristic of subcritical water is that its polarity can be dramatically decreased with increasing temperature. Therefore, subcritical water can behave similar to methanol or ethanol. Read More

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Preparation and Properties of Electrospun Phenylethynyl-Terminated Polyimide Nano-Fibrous Membranes with Potential Applications as Solvent-Free and High-Temperature Resistant Adhesives for Harsh Environments.

Nanomaterials (Basel) 2021 Jun 9;11(6). Epub 2021 Jun 9.

School of Materials Science and Technology, China University of Geosciences, Beijing 100083, China.

High-temperature-resistant polymeric adhesives with high servicing temperatures and high adhesion strengths are highly desired in aerospace, aviation, microelectronic and other high-tech areas. The currently used high-temperature resistant polymeric adhesives, such as polyamic acid (PAA), are usually made from the high contents of solvents in the composition, which might cause adhesion failure due to the undesirable voids caused by the evaporation of the solvents. In the current work, electrospun preimidized polyimide (PI) nano-fibrous membranes (NFMs) were proposed to be used as solvent-free or solvent-less adhesives for stainless steel adhesion. Read More

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Preparation of Soluble POSS-Linking Polyamide and Its Application in Antifogging Films.

Materials (Basel) 2021 Jun 9;14(12). Epub 2021 Jun 9.

Graduate School of Science and Engineering, Kagoshima University, Kagoshima 890-0065, Japan.

In this study, we prepared a polyhedral oligomeric silsesquioxane (POSS)-linking polyamide (POSS polyamide) by a polycondensation of ammonium-functionalized POSS (POSS-A) and carboxyl-functionalized POSS (POSS-C) in dehydrated dimethyl sulfoxide (DMSO) using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and -hydroxysuccinimide (NHS) as condensing agents. The obtained POSS polyamide was soluble in various highly polar solvents, and it could form a self-standing film. FT-IR, H NMR, and Si NMR analyses showed that POSS polyamide is a polymer in which POSS-A and POSS-C are linked almost linearly by amide bonds. Read More

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A Systematic Study on the Degradation Products Generated from Artificially Aged Microplastics.

Polymers (Basel) 2021 Jun 18;13(12). Epub 2021 Jun 18.

Department of Chemistry and Industrial Chemistry, University of Pisa, 56124 Pisa, Italy.

Most of the analytical studies focused on microplastics (MPs) are based on the detection and identification of the polymers constituting the particles. On the other hand, plastic debris in the environment undergoes chemical and physical degradation processes leading not only to mechanical but also to molecular fragmentation quickly resulting in the formation of leachable, soluble and/or volatile degradation products that are released in the environment. We performed the analysis of reference MPs-polymer micropowders obtained by grinding a set of five polymer types down to final size in the 857-509 μm range, namely high- and low-density polyethylene, polystyrene (PS), polypropylene (PP), and polyethylene terephthalate (PET). Read More

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