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An encapsulation/dehydration procedure was developed for Euglena gracilis Klebs as a 'model alga' to examine various cryoprotective regimes combined with controlled rate cooling to cryopreserve other Euglenoid taxa. Cryoprotective variables were optimised to enable reproducible growth following a combination of alginate encapsulation, sucrose osmotic dehydration, air desiccation, methanol treatment, cooling to -40 degrees C and plunging into liquid nitrogen (LN). Amplified Fragment Length Polymorphism (AFLP) analysis was adapted to: (i) verify algal identity by discriminating between different Euglenoids and (ii) examine the genetic stability of algal cultures prior to various stages of cryoprotective treatments and following exposure to LN. AFLPs were highly reproducible (> 99%) as reliable diagnostic markers, where a single DNA fragment change accounted for -0.4% of the detectable variation in an AFLP pattern. AFLP changes were detected in cryoprotective treatments following LN exposure. Successive stages of the dehydration and desiccation treatments did not accumulate AFLP changes indicating these are random events. 相似文献
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Hella Folkerts Dirk Nußhr Frank Weller Kurt Dehnicke Jrg Magull Wolfgang Hiller 《无机化学与普通化学杂志》1994,620(11):1986-1991
Phosphorane Iminato Complexes of Sulfur. Synthesis and Crystal Structures of [SO(Cl)(NPPh3)], [SO2(Cl)(NPPh3)], and [SCl(NPPh3)2]Cl The title compounds have been prepared by the reaction of Me3SiNPPh3 with SOCl2, SO2Cl2, and SCl2, respectively. They form colourless, moisture sensitive crystals, which were characterized by IR spectroscopy and by crystal structure determinations. [SO(Cl)(NPPh3)]: Space group P21/n, Z = 4, structure determination with 2 434 observed unique reflections, R = 0.047. Lattice dimensions at 19°C: a = 1 304.8, b = 996.5, c = 1 339.5 pm, β = 93.75°. The compound forms monomeric molecules with a remarkably long S? Cl bond of 234.2 pm and distances SN and PN of 154.6 and 161.6 pm, respectively, which agree with double bonds. [SO2(Cl)(NPPh3)]: Space group P21/n, Z = 4, structure solution with 2 872 observed, unique reflections, R = 0.047. Lattice dimensions at 20°C: a = 956.9, b = 1 909, c = 1 002.0 pm, β = 106.06°. The compound forms monomeric molecules with distances S? Cl of 207.1 pm, SN of 154.5 pm, and PN of 161.6 pm. [SCl(NPPh3)2]Cl: Space group P21/c, Z = 4, structure solution with 5 224 observed, unique reflections, R = 0.042. Lattice dimensions at 20°C: a = 1 108.6, b = 1 603.8, c = 1 840.5 pm, β = 99.98°. The compound forms ions [SCl(NPPh3)2]+ and Cl?. In the cation the sulfur atom is φ-tetrahedrally coordinated with a long S? Cl distance of 248.5 pm and SN bond lengths of 154.5 and 156.0 pm. 相似文献
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[(Me3PN)3SNS(NPMe3)2]Cl2, a Mixed Valenced Phosphorane Iminato Complex of Sulfur The title compound has been prepared from trithiazyl chloride and the silylated phosphaneimine Me3SiNPMe3 in acetonitrile solution, forming red crystals, which were characterized by IR spectroscopy and by a crystal structure determination. Space group P21/c, Z = 4, structure solution with 4250 independent reflections, R = 0.054. Lattice dimensions at 20°C: a = 1077.8, b = 2036.6, c = 1480.5 pm, β = 102.39°. The compound consists of dications [(Me3PN)3SNS(NPMe3)2]2+ and chloride ions. In the cations the sulfur atoms of oxidation number +VI and +IV are connected by an asymmetric, bent nitrido bridge with SN bond lengths of 156.9 and 167.0 pm. 相似文献
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This paper presents an optimal nonconforming adaptive finite element algorithm and proves its quasi-optimal complexity for the Stokes equations with respect to natural approximation classes. The proof does not explicitly involve the pressure variable and follows from a novel discrete Helmholtz decomposition of deviatoric functions. 相似文献
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Draksharapu A Li Q Logtenberg H van den Berg TA Meetsma A Killeen JS Feringa BL Hage R Roelfes G Browne WR 《Inorganic chemistry》2012,51(2):900-913
We report the characterization and solution chemistry of a series of Fe(II) complexes based on the pentadentate ligands N4Py (1,1-di(pyridin-2-yl)-N,N-bis(pyridin-2-ylmethyl)methanamine), MeN4Py (1,1-di(pyridin-2-yl)-N,N-bis(pyridin-2-ylmethyl)ethanamine), and the tetradentate ligand Bn-N3Py (N-benzyl-1,1-di(pyridin-2-yl)-N-(pyridin-2-ylmethyl)methanamine) ligands, i.e., [Fe(N4Py)(CH(3)CN)](ClO(4))(2) (1), [Fe(MeN4Py)(CH(3)CN)](ClO(4))(2) (2), and [Fe(Bn-N3Py)(CH(3)CN)(2)](ClO(4))(2) (3), respectively. Complexes 2 and 3 are characterized by X-ray crystallography, which indicates that they are low-spin Fe(II) complexes in the solid state. The solution properties of 1-3 are investigated using (1)H NMR, UV/vis absorption, and resonance Raman spectroscopies, cyclic voltammetry, and ESI-MS. These data confirm that in acetonitrile the complexes retain their solid-state structure, but in water immediate ligand exchange of the CH(3)CN ligand(s) for hydroxide or aqua ligands occurs with full dissociation of the polypyridyl ligand at low (<3) and high (>9) pH. pH jumping experiments confirm that over at least several minutes the ligand dissociation observed is fully reversible for complexes 1 and 2. In the pH range between 5 and 8, complexes 1 and 2 show an equilibrium between two different species. Furthermore, the aquated complexes show a spin equilibrium between low- and high-spin states with the equilibrium favoring the high-spin state for 1 but favoring the low-spin state for 2. Complex 3 forms only one species over the pH range 4-8, outside of which ligand dissociation occurs. The speciation analysis and the observation of an equilibrium between spin states in aqueous solution is proposed to be the origin of the effectiveness of complex 1 in cleaving DNA in water with (3)O(2) as terminal oxidant. 相似文献
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Gerald Steiner Olesya Savchuk Hella Mller Dirk Ferse Hans‐Jürgen Adler Reiner Salzer 《Macromolecular Symposia》2001,164(1):159-166
Self assembly monolayers of octadecyltrichlorosilane Cl3‐Si‐(CH2)17‐CH3 and 17‐cyanopentadecyltrichlorosilane Cl3‐Si‐(CH2)17‐CN on silicon wafers have been prepared by adsorption from solution. The molecular orientation within the monolayers was investigated by using Polarisation Modulation FTIR spectroscopy. Quantitative analysis reveals that both types of silanes – monofunctionalised and bifunctionalised – form highly ordered monolayers. A high degree of ordering as well as a small tilt angel of the molecular backbones with respect to the surface normal are indicated by the strength of the Si‐O‐Si stretching modes and the weakness of the CH2 stretching modes. The decomposition of the terminal nitrile group of the substituted silane into a carboxyl group could be identified. The decomposition is caused by a high local HCl concentration, which develops upon binding of 17‐cyanopentadecyltrichlorosilane to the OH groups of the silicon surface. 相似文献