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101.
Gregory MA Hong H Lill RE Gaisser S Petkovic H Low L Sheehan LS Carletti I Ready SJ Ward MJ Kaja AL Weston AJ Challis IR Leadlay PF Martin CJ Wilkinson B Sheridan RM 《Organic & biomolecular chemistry》2006,4(19):3565-3568
The function of gene products involved in the biosynthesis of the clinically important polyketide rapamycin were elucidated by biotransformation and gene complementation. 相似文献
102.
Tailor-made ligands for biocompatible nanoparticles 总被引:1,自引:0,他引:1
103.
Hrvoje Gebavi Daniel Milanese Qiuping Chen Mile Ivanda Stefano Taccheo 《Journal of Non》2009,355(9):548-26274
In this paper, optical properties of 75TeO2-20ZnO-5Na2O host glass doped with concentration of Tm3+ up to 10 %mol were studied in order to assess the most suitable rare earth content for short cavity fiber lasers. Raman spectroscopy revealed a change in the glass structure while increasing Tm3+ content, similar to the well known addition of alkali ions in a glass. Influence of the fabrication process on the OH− content was determined by FTIR measurements. Refractive index of Tm3+ doped tellurite glasses was measured at five different wavelengths ranging from 533 nm to 1533 nm. Lifetime and emission spectra measurements of the Tm3+ doped tellurite glasses are reported. 相似文献
104.
The maximum entropy (MaxEnt) principle is a versatile tool for statistical inference of the probability density function (pdf) from its moments as a least-biased estimation among all other possible pdf’s. It maximizes Shannon entropy, satisfying the moment constraints. Thus, the MaxEnt algorithm transforms the original constrained optimization problem to the unconstrained dual optimization problem using Lagrangian multipliers. The Classic Moment Problem (CMP) uses algebraic power moments, causing typical conventional numerical methods to fail for higher-order moments (m>5–10) due to different sensitivities of Lagrangian multipliers and unbalanced nonlinearities. Classic MaxEnt algorithms overcome these difficulties by using orthogonal polynomials, which enable roughly the same sensitivity for all Lagrangian multipliers. In this paper, we employ an idea based on different principles, using Fupn basis functions with compact support, which can exactly describe algebraic polynomials, but only if the Fup order-n is greater than or equal to the polynomial’s order. Our algorithm solves the CMP with respect to the moments of only low order Fup2 basis functions, finding a Fup2 optimal pdf with better balanced Lagrangian multipliers. The algorithm is numerically very efficient due to localized properties of Fup2 basis functions implying a weaker dependence between Lagrangian multipliers and faster convergence. Only consequences are an iterative scheme of the algorithm where power moments are a sum of Fup2 and residual moments and an inexact entropy upper bound. However, due to small residual moments, the algorithm converges very quickly as demonstrated on two continuous pdf examples – the beta distribution and a bi-modal pdf, and two discontinuous pdf examples – the step and double Dirac pdf. Finally, these pdf examples present that Fup MaxEnt algorithm yields smaller entropy value than classic MaxEnt algorithm, but differences are very small for all practical engineering purposes. 相似文献
105.
106.
Hrvoje Nikolić 《Foundations of Physics》2007,37(11):1563-1611
A common understanding of quantum mechanics (QM) among students and practical users is often plagued by a number of “myths”,
that is, widely accepted claims on which there is not really a general consensus among experts in foundations of QM. These
myths include wave-particle duality, time-energy uncertainty relation, fundamental randomness, the absence of measurement-independent
reality, locality of QM, nonlocality of QM, the existence of well-defined relativistic QM, the claims that quantum field theory
(QFT) solves the problems of relativistic QM or that QFT is a theory of particles, as well as myths on black-hole entropy.
The fact is that the existence of various theoretical and interpretational ambiguities underlying these myths does not yet
allow us to accept them as proven facts. I review the main arguments and counterarguments lying behind these myths and conclude
that QM is still a not-yet-completely-understood theory open to further fundamental research. 相似文献
107.
Hrvoje Nikolić 《Foundations of Physics Letters》2000,13(6):595-601
We study the role of acceleration in the twin paradox. From the coordinate transformation that relates an accelerated and an inertial observer we find that, from the point of view of the accelerated observer, the rate of the differential lapses of time depends not only on the relative velocity, but also on the product of the acceleration and the distance between the observers. However, this result does not have a direct operational interpretation because an observer at a certain position can measure only physical quantities that are defined at the same position. For local measurements, the asymmetry between the two observers can be attributed to the fact that noninertial coordinate systems, contrary to inertial coordinate systems, can be correctly interpreted only locally. 相似文献
108.
Hrvoje Nikolic 《General Relativity and Gravitation》1999,31(8):1211-1217
In a nongeometrical interpretation of gravity,the metric g(x) = + (x)is interpreted as an effective metric, whereas(x) is interpreted as afundamental gravitational field, propagated in spacetime which isactually flat. Some advantages and disadvantages of suchan interpretation are discussed. The main advantage isa natural resolution of the flatness problem. 相似文献
109.
Gu C Nikolic D Lai J Xu X van Breemen RB 《Combinatorial chemistry & high throughput screening》1999,2(6):353-359
Two approaches were utilized to increase the throughput of pulsed ultrafiltration assays of ligand binding to human serum albumin, reducing the volume of the ultrafiltration chamber and combining pulsed ultrafiltration with high performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC-MS). Affinity constants for binding of ligands to human serum albumin were determined using pulsed ultrafiltration with ultraviolet absorbance detection. The first affinity constants (Ka1) were measured for the binding of dansylsarcosine, dansylamide, 7-anilinocoumarin-4-acetic acid and warfarin, and were determined to be 1.8 x 105, 5 x 104, 8 x 104, and 2.0 x 105 M-1, respectively. The throughput of pulsed ultrafiltration analyses was tripled compared to previous pulsed ultrafiltration measurements by reducing the volume of the chamber. In addition, the use of LC-MS with pulsed ultrafiltration permitted the simultaneous comparison and rank ordering of ligand mixtures for binding to serum albumin. For example, the throughput of these pulsed ultrafiltration measurements was tripled by analyzing three ligands as a mixture. 相似文献
110.
Snezana D. Nikolic Teodora D. Jankovi Emil B. Milosavljevi James L. Hendrix John H. Nelson 《Fresenius' Journal of Analytical Chemistry》1992,342(1-2):98-102
Summary A rapid, indirect diffusion flow injection analysis (FIA) method with amperometric detection has been developed for the selective and sensitive determination of Br–. The method is based on permanganate oxidation of Br– to bromine. Bromine diffuses through a PTFE membrane and is quantified amperometrically at a platinum working electrode. Calibration graphs were linear up to the maximum concentration of Br– investigated (10.0 mmol/l). The precision of the technique was better than a relative standard deviation of 0.7% at 10.0 mol/l, with a throughput of 30 samples per hour. The effects of temperature, acidity, working potential, composition of the reagent solution and interferents on the FIA signals were studied. The catalytic effect of Cl– on the permanganate oxidation of the analyte was utilized to lower the detection limit to 1 mol/l (16 ng Br–). Similar detection limits were achieved by combining the effects of higher acidity (4.0 mol/l H2SO4) and elevated temperatures (40°C). The method was successfully applied to the determination of Br– in chloride and other reagents, as well as in natural waters. 相似文献