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32.
Nitrido-Sodalithe. III [1]. Synthese,Struktur und Eigenschaften von Zn8[P12N24]X2 mit X = O,S, Se,Te
Nitrido-Sodalites. III. Synthesis, Crystal Structure, and Properties of Zn8[P12N24]X2 with X = O, S, Se, Te The P? N-sodalites Zn8[P12N24]X2 with X = O, S, Se, Te are obtained by the reaction of HPN2 with the corresponding zinc chalcogenide ZnX at 750°C. They crystallize in a filled up variant of Zn7[P12N24]Cl2 and are isotypic to Zn8[B12O24]O2 (I4 3m, a = 823 to 830 pm, Z = 1). The P? N-sodalites contain in the center of their β-cages XZn46+ units which can be described as sections of II/VI-semiconductors. The UV/Vis-spectra of the compounds show in comparison with binary bulk zinc chalcogenides a blue shift of the absorption edge according to the size quantization effect. 相似文献
33.
A common approach for comparing the structures of biomolecules or solid bodies is to translate and rotate one structure with respect to the other to minimize the pointwise root-mean-square deviation (RMSD). We present a new, robust numerical algorithm that computes the RMSD between two molecules or all the mutual RMSDs of a list of molecules and, if desired, the corresponding rotation matrix in a minimal number of operations as compared to previous algorithms. The RMSD gradient can also be computed. We address the problem of symmetry, both in alignment (possible alternative alignments due to indistinguishable atoms) as well as geometry. In the latter case, it is possible to have degenerate superposition. A necessary condition is optimal superimposability to one's mirror image. Double (respectively, triple) degeneracy results in a one- (respectively, two)-parameter family of rotations leaving the superposition invariant. The software, frmsd , is freely available at http://www.ams.stonybrook.edu/~coutsias/codes/frmsd.tgz . © 2019 Wiley Periodicals, Inc. 相似文献
34.
Alexander von Zastrow Rico Otto Sébastien Jézouin Jonathan Brox Martin Stei Olmo González-Magaña Geert Reitsma Thomas Schlathölter Ronnie Hoekstra Thorsten Best Roland Wester 《Applied physics. B, Lasers and optics》2014,114(1-2):251-255
Energetic impact of multiple ionized oxygen on protonated water clusters in the range of eight to twenty-one water molecules is investigated on the ZERNIKE--LEIF facility. The target water clusters are stored in a Paul trap and thermalized by cold buffer gas. This well-controlled approach allows for a direct measurement of the total inelastic cross section leading to trap-loss processes of the target ions. 相似文献
35.
An improved method for the solution-phase derivatization of Tyr3-Lys5(Dde)-octreotide (TOC(Dde)) and Tyr3-Lys5(Dde)-octreotate (TATE(Dde)) with the macrocyclic chelator DOTA (1,4,7,10-tetraazacyclododecane-N′,N″,N?,N?-tetraacetic acid) has been developed. The fully protected parent peptides were assembled via solid-phase peptide synthesis (SPPS) using Fmoc-strategy. After cleavage from the solid support, disulfide bond formation was carried out using H2O2. Both TOC(Dde) and TATE(Dde) were successfully coupled with DOTA in the presence of NHS, EDCI and DIPEA in a water/DMF solvent system. Yields of the coupling reaction were >98% within only 2 h with no detectable formation of sideproducts. This method for the preparation of DOTATOC, DOTATATE and other DOTA-peptide conjugates is therefore a rapid and economic alternative to the currently used methods. 相似文献
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37.
Background
Amyotrophic lateral sclerosis (ALS) is an age-dependent neurodegenerative disease that causes motor neuron degeneration, paralysis and death. Mutations in Cu, Zn superoxide dismutase (SOD1) are one cause for the familial form of this disease. Transgenic mice expressing mutant SOD1 develop age-dependent motor neuron degeneration, skeletal muscle weakness, paralysis and death similar to humans. The mechanism whereby mutant SOD1 induces motor neuron degeneration is not understood but widespread mitochondrial vacuolation has been observed during early phases of motor neuron degeneration. How this vacuolation develops is not clear, but could involve autophagic vacuolation, mitochondrial permeability transition (MPT) or uncharacterized mechanisms. To determine which of these possibilities are true, we examined the vacuolar patterns in detail in transgenic mice expressing mutant SOD1G93A. 相似文献38.
van Eis MJ van Der Linde BS de Kanter FJ de Wolf WH Bickelhaupt F 《The Journal of organic chemistry》2000,65(14):4348-4354
In contrast to the terminal phosphinidene complex PhPW(CO)(5) (2), which adds to [5]metacyclophane (1) in a 1,4-fashion, dichlorocarbene preferentially adds in a 1,2-fashion to the formal "anti-Bredt" type double bond of the aromatic ring of 1 to afford the norcaradiene 11b, which immediately rearranges to the bridged cycloheptatriene 12b and further by a [1,5] sigmatropic chlorine migration to the isomeric 13b as the first observable product. More slowly, the latter isomerizes via a dissociative mechanism to give 15b. A computational study supports the notion that the [1,5] chlorine migration in the rearrangement 12b --> 13b, for which an activation barrier of 70.2 kJ mol(-)(1) was calculated, is essentially concerted with minor charge separation. In contrast, the analogous [1,5] chlorine migration in the flat model compound 7,7-dichlorocycloheptatriene (12a) displays features of a dissociative pathway. 相似文献
39.
Turini N Ukegawa F Valls J Vejcik S Velev G Vidal R Vilar R Vologouev I Vucinic D Wagner RG Wagner RL Wahl J Wallace NB Walsh AM Wang C Wang CH Wang MJ Watanabe T Watts T Webb R Wenzel H Wester WC Wicklund AB Wicklund E Williams HH Wilson P 《Physical review letters》2000,84(8):1663-1668
We have studied the production of B hadrons in 1.8-TeV pp[over ˉ] collisions. We present measurements of the fragmentation fractions, f_{u}, f_{d}, f_{s}, and f_{baryon}, of produced b quarks that yield B^{+}, B^{0}, B_{s}^{0}, and Λ[over ˉ]_{b}^{0} hadrons. Reconstruction of five electron-charm final states yields f_{s}/( f_{u}+f_{d})=0.213±0.068 and f_{baryon}/( f_{u}+f_{d})=0.118±0.042, assuming f_{u}=f_{d}. If all B hadrons produced in pp[over ˉ] collisions cascade to one of these four hadrons, we determine f_{u}=f_{d}=0.375±0.023, f_{s}=0.160±0.044, and f_{baryon}=0.090±0.029. If we do not assume f_{u}=f_{d}, we find f_{d}/f_{u}=0.84±0.16. 相似文献
40.