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941.
Pavlína Pelcová Jana Margetínová Tomáš Vaculovič Josef Komárek Vlastimil Kubáň 《Central European Journal of Chemistry》2010,8(1):116-125
Abiotic parameters (pH, temperature, current velocity, mercury species concentration, and sediment and aqueous media composition)
influence mercury species (MeHg+, EtHg+, PhHg+ and inorganic Hg2+) adsorption on river sediments. The highest amount of adsorbed MeHg+ and EtHg+ (82–93% and 85–91% for static and agitated system, respectively) occurred at pH 3–4. For PhHg+ the maximum adsorption (90% and 95% for static and agitated systems) was located over the broad 3–10 pH range, while for
Hg2+ (94% and 97% for static and agitated systems) it was at pH ∼ 3. Temperature (4.5–60°C) influenced the adsorption rate but
not the quantity. Both rate and quantity increased in the order: static < agitated ≤ stirred systems. The aqueous medium composition
affected both rate and quantity. Sulfate caused the largest adsorption decrease for organomercury species (15–25% decrease);
sulfide reduced Hg2+ adsorption about 67%. Cations at pH 5.2 reduced either the adsorption rate (Ca2+, Al3+) or the total adsorption (Zn2+, Fe3+). Positive correlations were found between sediment C, N, S content as well as cation exchange capacity (CEC) with mercury
adsorption (R = 0.45–0.66, 0.56–0.89, 0.45–0.61 and 0.55–0.73, respectively) while negative correlations were observed with
Fe and Al (R = −0.63 to −0.90 and −0.65 to −0.86, respectively). 相似文献
942.
943.
Bartelmess J Ballesteros B de la Torre G Kiessling D Campidelli S Prato M Torres T Guldi DM 《Journal of the American Chemical Society》2010,132(45):16202-16211
In the present work, a new family of pyrene (Py)-substituted phthalocyanines (Pcs), i.e., ZnPc-Py and H(2)Pc-Py, were designed, synthesized, and probed in light of their spectroscopic properties as well as their interactions with single-wall carbon nanotubes (SWNTs). The pyrene units provide the means for non-covalent functionalization of SWNTs via π-π interactions. Such a versatile approach ensures that the electronic properties of SWNTs are not impacted by the chemical modification of the carbon skeleton. The characterization of ZnPc-Py/SWNT and H(2)Pc-Py/SWNT has been performed in suspension and in thin films by means of different spectroscopic and photoelectrochemical techniques. Transient absorption experiments reveal photoinduced electron transfer between the photoactive components. ZnPc-Py/SWNT and H(2)Pc-Py/SWNT have been integrated into photoactive electrodes, revealing stable and reproducible photocurrents with monochromatic internal photoconversion efficiency values for H(2)Pc-Py/SWNT as large as 15 and 23% without and with an applied bias of +0.1 V. 相似文献
944.
Kee JM Villani B Carpenter LR Muir TW 《Journal of the American Chemical Society》2010,132(41):14327-14329
Protein phosphorylation is one of the most common and extensively studied posttranslational modifications (PTMs). Compared to the O-phosphorylation of Ser, Thr, and Tyr residues, our understanding of histidine phosphorylation is relatively limited, particularly in higher eukaryotes, due to technical difficulties stemming from the intrinsic instability and isomerism of phosphohistidine (pHis). We report the design and synthesis of stable and nonisomerizable pHis analogues. These pHis analogues were successfully utilized in solid-phase peptide synthesis and semi-synthesis of histone H4. Significantly, the first antibody that specifically recognizes pHis was obtained using the synthetic peptide as the immunogen. 相似文献
945.
Rubio BK Parrish SM Yoshida W Schupp PJ Schils T Williams PG 《Tetrahedron letters》2010,51(51):6718-6721
Bouillomides A (1) and B (2) are two depsipeptide analogues of dolastatin 13. Isolated from a Guamanian sample of Lyngbya bouillonii, the planar structures were elucidated on the basis of HR-ESI-MS and NMR data, while the absolute configurations were determined by employing functional group conversions, modified Marfey’s analysis, and detailed analyses of ROESY correlations. Compounds 1 and 2 selectively inhibited serine proteases elastase (IC50 = 1.9 μM for both) and chymotrypsin (IC50 = 0.17 and 9.3 μM, respectively) while showing no inhibition of trypsin (IC50 >100 μM). 相似文献
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947.
Colleflaccinosides A and B, two chiral bianthraquinone glycosides from the two geographical varieties of lichen Collema flaccidum collected in Russia and Israel have been isolated as new natural products. Their structures were elucidated using UV, CD, IR, MS, 1D and 2D NMR spectral data, and chemical degradation. The colleflaccinosides B had significant antitumor activity in the crown gall tumor inhibition test. 相似文献
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