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101.
102.
The marginal distributions of the number of rises and the number of falls have been used successfully in various areas of statistics, especially in non-parametric statistical inference. Carlitz (1972, Duke Math. J.39, 268–269) showed that the generating function of the joint distribution for the numbers of rises and falls satisfies certain complex combinatorial equations, and pointed out that he had been unable to derive the explicit formula for the joint distribution from these equations. After more than two decades, this latter problem remains unsolved. In this article, the joint distribution is obtained via the probabilistic method of finite Markov chain imbedding for random permutations. A numerical example is provided to illustrate the theoretical results and the corresponding computational procedures. 相似文献
103.
Using experiments and theory, we show that light scattering by inhomogeneities in the index of refraction of a fluid can drive a large-scale flow. The experiment uses a near-critical, phase-separated liquid, which experiences large fluctuations in its index of refraction. A laser beam traversing the liquid produces a interface deformation on the scale of the experimental setup and can cause a liquid jet to form. We demonstrate that the deformation is produced by a scattering-induced flow by obtaining good agreements between the measured deformations and those calculated assuming this mechanism. 相似文献
104.
Treatment of a primary t-butyl carbamate (Boc) group with excess sodium t-butoxide in slightly wet tetrahydrofuran or 2-methyltetrahydrofuran provides the corresponding primary amine in excellent yield. We believe the reaction proceeds through an isocyanate intermediate. 相似文献
105.
Sahar?Alhogail Ghadeer?A.?R.?Y.?Suaifan Sergio?Bizzarro Wendy?E.?Kaman Floris?J.?Bikker Karina?Weber Dana?Cialla-May Jürgen?Popp Mohammed?ZourobEmail author 《Mikrochimica acta》2018,185(2):149
Porphyromonas gingivalis (P. gingivalis) is a pathogen causing periodontitis. A rapid assay is described for the diagnosis of periodontal infections related to P. gingivalis. The method is making use of gingipains, a group of P. gingivalis specific proteases as a detection biomarker. Magnetic-nanobeads were labeled with gingipain-specific peptide substrates and immobilized on a gold biosensing platform via gold-thiol linkage. As a result of this, the color of the gold layer turns black. Upon cleavage of the immobilized substrates by gingipains, the magnetic-nanobeads-peptide fragments were attracted by a magnet so that the golden surface color becomes visible again. This assay is highly sensitive and specific. It is capable of detecting as little as 49 CFU·mL?1 of P. gingivalis within 30 s. Examination of periodontitis patients and healthy control saliva samples showed the potential of the assay. The simplicity and rapidity of the assay makes it an effective point-of-care device. 相似文献
106.
107.
The nocardicins are members of a class of monocyclic beta-lactam antibiotics produced by the actinomycete Nocardia uniformis subsp. tsuyamanesis (ATCC 21806). The oxime moiety in nocardicin A is required for full biological activity and is rare among natural products. A putative gene cluster encoding the enzymes of the nocardicin biosynthetic pathway has been identified. Among these, NocL shows similarity to cytochromes P450. We describe its heterologous expression and demonstrate its role in the formation of this unusual structural feature in nocardicin A. This is the first gene from this pathway to be expressed and its function established, and it is the first example of oxime formation from a primary amine in bacteria unambiguously linked to a cytochrome P450. 相似文献
108.
109.
Luminescence Behavior of Polynuclear Alkynylcopper(I) Phosphines 总被引:1,自引:0,他引:1
A series of soluble trinuclear and tetranuclear copper(I) complexes containing 3-l acetylides
, and
have been synthesized and shown to exhibit rich photoluminescent behavior at room temperature. The electrochemistry of the trinuclear Cu(I) acetylide complexes and the excited-state redox properties of
have been investigated. The X-ray crystal structures of
and
have been determined. 相似文献
110.
Huang R Kubelka J Barber-Armstrong W Silva RA Decatur SM Keiderling TA 《Journal of the American Chemical Society》2004,126(8):2346-2354
Infrared (IR) and vibrational circular dichroism (VCD) spectra were measured for a series of isotopically ((13)C on two or more amide Cdouble bond]O) labeled, 25 residue, alpha-helical peptides of the sequence Ac-(AAAAK)(4)AAAAY-NH(2) that were also studied in the previous paper. Theoretical IR and VCD simulations were performed for correspondingly isotopically labeled Ac-A(24)-NHCH(3) constrained to an alpha-helical conformation by use of property tensor transfer from density functional theory (DFT) calculations on Ac-A(10)-NHCH(3). The simulations predicted and experiments confirmed that the vibrational coupling constants between i, i + 1 and i, i + 2 residues differ in sign, thus leading to a reversal of the (13)C VCD pattern and explaining the large shift in the (13)C amide I frequency as reported in the previous paper. The sign of the coupling constant remained consistent for larger label separation (with the exception of i, i + 4) and for more labels with uniform separation. Such effects confirm that the isotopically labeled group vibrations are essentially only coupled to each other and are effectively uncoupled from those of the unlabeled groups. This development confirms the utility of isotopic labels for site-specific structural studies with vibrational spectra. Observed spectral effects cannot be explained by considering only transition dipole coupling (TDC) between amide oscillators, particularly for smaller label separations, but the TDC and ab initio predicted couplings roughly converge at large separation. 相似文献