111,523 research outputs found
Carbonyl sulfide (COS) as a tracer for canopy photosynthesis, transpiration and stomatal conductance : potential and limitations
No full textThe theoretical basis for the link between the leaf exchange of carbonyl sulfide (COS), carbon dioxide (CO2) and water vapour (H2O) and the assumptions that need to be made in order to use COS as a tracer for canopy net photosynthesis, transpiration and stomatal conductance, are reviewed. The ratios of COS to CO2 and H2O deposition velocities used to this end are shown to vary with the ratio of the internal to ambient CO2 and H2O mole fractions and the relative limitations by boundary layer, stomatal and internal conductance for COS. It is suggested that these deposition velocity ratios exhibit considerable variability, a finding that challenges current parameterizations, which treat these as vegetation-specific constants. COS is shown to represent a better tracer for CO2 than H2O. Using COS as a tracer for stomatal conductance is hampered by our present poor understanding of the leaf internal conductance to COS. Estimating canopy level CO2 and H2O fluxes requires disentangling leaf COS exchange from other ecosystem sources/sinks of COS. We conclude that future priorities for COS research should be to improve the quantitative understanding of the variability in the ratios of COS to CO2 and H2O deposition velocities and the controlling factors, and to develop operational methods for disentangling ecosystem COS exchange into contributions by leaves and other sources/sinks. To this end, integrated studies, which concurrently quantify the ecosystem-scale CO2, H2O and COS exchange and the corresponding component fluxes, are urgently needed.
We investigate the potential of carbonyl sulfide (COS) for being used as a tracer for canopy net photosynthesis, transpiration and stomatal conductance by examining the theoretical basis of the link between leaf COS, carbon dioxide (CO2) and water vapour (H2O) exchange. Our analysis identifies several limitations that need to be overcome to this end, however at present we lack appropriate ecosystem-scale field measurements for assessing their practical significance. It however appears that COS represents a better tracer for CO2 than H2O. Concurrent measurements of ecosystem scale COS, CO2 and H2O exchange are advocated
The flux of carbonyl sulfide and carbon disulfide between the atmosphere and a spruce forest
No full textTurbulent fluxes of carbonyl sulfide (COS) and carbon disulfide (CS2) were measured over a spruce forest in Central Germany using the relaxed eddy accumulation (REA) technique. A REA sampler was developed and validated using simultaneous measurements of CO2 fluxes by REA and by eddy correlation. REA measurements were conducted during six campaigns covering spring, summer, and fall between 1997 and 1999. Both uptake and emission of COS and CS2 by the forest were observed, with deposition occurring mainly during the sunlit period and emission mainly during the dark period. On the average, however, the forest acts as a sink for both gases. The average fluxes for COS and CS2 are -93 ± 11.7 pmol m-2 s-1 and -18 ± 7.6 pmol m-2 s-1, respectively. The fluxes of both gases appear to be correlated to photosynthetically active radiation and to the CO2 and \chem{H_2O} fluxes, supporting the idea that the air-vegetation exchange of both gases is controlled by stomata. An uptake ratio COS/CO2 of 10 ± 1.7 pmol m mol-1 has been derived from the regression line for the correlation between the COS and CO2 fluxes. This uptake ratio, if representative for the global terrestrial net primary production, would correspond to a sink of 2.3 ± 0.5 Tg COS yr-1
Cell Type-Dependent Specificity and Anti-Inflammatory Effects of Charge-Reversible MSNs-COS-CMC for Targeted Drug Delivery in Cervical Carcinoma
No full textThe surface charge of nanocarriers
inevitably affects drug delivery
efficiency; however, the cancer cell specificity, anti-inflammatory
effects, and charge-reversal points remain to be further addressed
in biomedical applications. The aim of this study was to comprehensively
assess the cancer cell specificity of DOX-loaded mesoporous silica-chitosan
oligosaccharide-carboxymethyl chitosan nanoparticles (DOX@MSNs-COS-CMC)
in MCF-7 and HeLa cells, inhibit the production of inflammatory cytokines,
and improve the drug accumulation in the tumor site. Intracellular
results reveal that the retention time prolonged to 48 h in both HeLa
and MCF-7 cells at pH 7.4. However, DOX@MSNs-COS-CMC exhibited a cell
type-dependent cytotoxicity and enhanced intracellular uptake in HeLa
cells at pH 6.5, due to the clathrin-mediated endocytosis and macropinocytosis
in HeLa cells in comparison with the vesicular transport in MCF-7
cells. Moreover, Pearson’s correlation coefficient value significantly
decreased to 0.25 after 8 h, prompting endosomal escape and drug delivery
into the HeLa nucleus. After the treatment of MSNs-COS-CMC at 200
μg/mL, the inflammatory cytokines IL-6 and TNF-α level
decreased by 70% and 80%, respectively. Tumor inhibition of DOX@MSNs-COS-CMC
was 0.4 times higher than free DOX, alleviating cardiotoxicity and
inflammation in the HeLa xenograft tumor model. Charge-reversible
DOX@MSNs-COS-CMC could be a possible candidate for clinical therapy
of cervical carcinoma
H&M och COS – House of Brands eller Branded House
No full textUtifrån varumärkesteorier undersöka vilka konsekvenser H&M´s beslut att lansera sitt nya varumärke COS som ett fristående varumärke utan någon synlig koppling till H&M har haft på konsumenternas uppfattning om varumärkena. Vi dragit slutsatsen att konsumenterna påverkas positivt av H&M´s val att övergå till ett House of Brands och lansera COS som ett fristående varumärke. Den osynliga, men samtidigt tydliga kopplingen är en viktig framgångsfaktor
Dithiasuccinoyl-Caged Amines Enables COS/H2S Release Lacking Electrophilic Byproducts
No full textThe
enzymatic conversion of carbonyl sulfide (COS) to hydrogen sulfide (H2S)
by carbonic anhydrase has been used to develop self-immolating thiocarbamates
as COS-based H2S donors to further elucidate the impact of reactive
sulfur species in biology. The high modularity of this approach has provided a
library of COS-based H2S donors that can be activated by specific
stimuli. A common limitation, however, is that many such donors result in the
intermediate formation of an electrophilic quinone methide byproduct during
donor activation. As a mild alternative, we demonstrate here that
dithiasuccinoyl groups can function as COS/H2S donor motifs and that
these groups release two equivalents of COS/H2S and uncage an amine
payload under physiologically relevant conditions. Additionally, we demonstrate
that COS/H2S release from this donor motif can be altered by
electronic modulation and alkyl substitution. These insights are further
supported by DFT investigations, which reveal that aryl and alkyl
thiocarbamates release COS with significantly different activation energies.</p
Double spin asymmetries A(LT)(cos) (phi S) and A(LT)(cos(2 phi h-phi S)) in semi-inclusive DIS
No full textWe investigate the double spin asymmetries of pion production in semi-inclusive deep inelastic scattering with a longitudinal polarized beam off a transversely polarized proton target. Particularly, we consider the cos phi(s) and cos(2 phi(h) - phi(s)) modulations, which can be interpreted by the convolution of the twist-3 transverse momentum dependent distributions and twist-2 fragmentation functions. Three different origins are taken into account simultaneously for each asymmetry: the g(T)D(1) term, the e(T)H(1)(perpendicular to) term, and the e(T)(perpendicular to)H(1)(perpendicular to) term in the cos phi(s) asymmetry; and the g(T)(perpendicular to)D(1) term, the e(T)H(1)(perpendicular to) term, and the e(T)(perpendicular to)H(1)(perpendicular to) term in the cos(2 phi(h) - phi(s)) asymmetry. We calculate the four twist-3 distributions g(T)(x, k(T)(2)), g(T)(perpendicular to)(x, k(T)(2)), e(T)(x, k(T)(2)) and e(T)(perpendicular to)(x, k(T)(2)) in a spectator-diquark model including vector diquarks. Then we predict the two corresponding asymmetries for charged and neutral pions at the kinematics of HERMES, JLab, and COMPASS for the first time. The numerical estimates indicate that the two different angular-dependence asymmetries are sizable by several percent at HERMES and JLab, and the cos phi(s) asymmetry has a strong dependence on the Bjorken x. Our predictions also show that the dominant contribution to the cos phi(s) asymmetry comes from the g(T)D(1) term, while the g(T)(perpendicular to)D(1) term gives the main contribution to the cos(2 phi(h) - phi(s)) asymmetry; the other two T-odd terms almost give negligible contributions. In particular, the cos(2 phi(h) - phi(s)) asymmetry provides a unique opportunity to probe the distribution g(T)(perpendicular to).http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000350105700007&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Astronomy & AstrophysicsPhysics, Particles & FieldsSCI(E)[email protected]; [email protected]; [email protected]
Basic Metals. XIV. Synthesis and Crystal Structure of CH(PMe)CoS : A New Metallapentathia Heterocycle
No full textDer Zweikernkomplex CH(PMe)Co(-CO)Mn(CO)CHMe (8) reagiert mit stöchiometrischen Mengen S in praktisch quantitativer Ausbeute zu CH(PMe)CoS (4). Der Koba.ltapentathia-Heterocyclus 4 ist ebenfalls aus CH(PMe)Co(h-CS) (5) und S zugänglich. 4 kristallisiert monoklin mit den Gitterkonstanten a = 8,467(3) A, b = 12,128(4) A, c = 14,210(4) A und = 102,20(2)°_ Die Sesselform des sechsgliedrigen CoS-Rings entspricht derjenigen in den bekannten Verbindungen (CH)TiS und (CH)VS , wobei in 4 der Cyclopentadienylligand die axiale und die Trimethylphosphingruppe die ä.quatoriale Position einnehmen.The dinuclear complex CH(PMe)Co(-CO)Mn(CO)CHMe (8) reaots with stoichiometric amounts of S to form CH(PMe)CoS (4) in practica.lly quantitative yields. The cobalt. apentathia heterocycle 4 is a.lso obtained by the reaction of CH(PMe)Co(h-CS) (5) with S, Cry. stals of 4 are monoclinic with a = 8.467(3) A, b = 12.128(4) A, c = 14.210(4) A and = 102.20(2)°. The chair form of the six·membered CoS ringcorresponds to that of the compounds (CH)TiS and (CH)VS In 4, the cyclopentadienyl ligand occupies the axial and the trimethylphosphine group the equatorial position
On the cos phi(h) asymmetry in electroproduction of pions in double longitudinally polarized process
No full textWe study the cos phi(h) azimuthal asymmetry in double polarized semi-inclusive pion production by considering the twist-3 effects directly from a quark quark correlator. In particular, we evaluate the role of the transverse momentum dependent distributions e(L)(x,k(T)(2),) and g(L)(perpendicular to) (x, k(T)(2),) on the asymmetry. Using two different sets of spectator model results for these distributions, we predict the cos phi(h) asymmetry of pi(+), pi(-) and pi(0) at the kinematic configuration available at CLAS, HERMES. Our estimate shows that the asymmetries for charged and neutral pions are sizable and could be accessed by CLAS and HERMES. We also calculate the asymmetries for charged hadrons at the kinematics of COMPASS and compare them with the experimental data. We find that the asymmetry at COMPASS in our model is small which is consistent with the COMPASS data. We also find that g(L)(perpendicular to) gives the dominant contribution to the cos phi(h) asymmetry, while the contribution of e(L), is almost negligible. (C) 2015 Elsevier B.V. All rights reserved.National Natural Science Foundation of China [11575043, 11120101004, 11035003]; Qing Lan Project (China)SCI(E)[email protected]; [email protected]
H- and auxiliary functions for phase functions of the type p (Cos θ ) = ω<SUB>0</SUB> + ω<SUB>1</SUB>P<SUB>1</SUB>(Cos θ) + ω<SUB>2</SUB>P<SUB>2</SUB>(Cos θ)
No full textH- and auxiliary functions are tabulated for nonconservative scattering for phase functions of type p (Cos θ ) = ω0 + ω1P1 (Cos θ) + ω2P2× (Cos θ). They have been computed for 15 values of the single scattering albedo and for 37 pairs of ω-1 =ω1/ ω0 and ω-2 = ω2/ω0
H- and auxiliary functions for phase functions of the type p (Cos θ ) = ω<SUB>0</SUB> + ω<SUB>1</SUB>P<SUB>1</SUB>(Cos θ) + ω<SUB>2</SUB>P<SUB>2</SUB>(Cos θ)
No full textH- and auxiliary functions are tabulated for nonconservative scattering for phase functions of type p (Cos θ ) = ω0 + ω1P1 (Cos θ) + ω2P2× (Cos θ). They have been computed for 15 values of the single scattering albedo and for 37 pairs of ω-1 =ω1/ ω0 and ω-2 = ω2/ω0
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