Influence of the soliton in anharmonic molecular crystals with temperature on Mössbauer effect

The influence of a soliton on the properties of the M?ssbauer effect resulting from the gamma-active nuclei situated at lattice sites in quasi-one-dimensional anharmonically organic molecular chains, in which the active nuclei emit gamma-photons, has been theoretically studied by a quantum vibrational model. An expression for the gamma-radiated M?ssbauer transition probability as a function of the temperature and non-linear interaction has been obtained. Finally we give some new properties of this effect from numerical calculation in such a case, which present a way to experimentally confirm the soliton existence in molecular crystals. Received 9 April 1998 and Received in final form 11 December 1998     

Fast Algorithms for Finding O(Congestion + Dilation) Packet Routing Schedules

O (c+d) steps using constant-size queues, where c is the congestion of the paths in the network, and d is the length of the longest path. The proof, however, used the Lovász Local Lemma and was not constructive. In this paper, we show how to find such a schedule in time, with probability , for any positive constant β, where is the sum of the lengths of the paths taken by the packets in the network, and m is the number of edges used by some packet in the network. We also show how to parallelize the algorithm so that it runs in NC. The method that we use to construct the schedules is based on the algorithmic form of the Lovász Local Lemma discovered by Beck. Received: July 8, 1996     

Normally generated line bundles of smallest degree on curves

In this paper we study the embeddings of smallest degree of a generic curveC of genusg as a projectively normal curve.

---

Sunto In questo articolo studiamo le immersioni di grado minimo di una generica curvaC di genereg come curva proiettivamente normale.

     

Influence of Fe3+ on perovskite oxides: La2/3Ca1/3Mn1-x Fe x O3

The structure and magnetoresistance properties in sintered samples of La_2/3Ca_1/3Mn_1-x Fe _x O₃(0≤x≤0.84) are studied by using Mössbauer spectroscopy, XRD and magnetic measurement. There are antiferromagnetic interactions between Fe and its nearest neighbors (Fe, Mn) when 0 <x ≤0.67, which are important factors influencing the double-exchange between Mn³⁺ and Mn⁴⁺, Curie temperature, magnetic moment and GMR. It is suggested that the Mn³⁺ (Fe³⁺) /Mn⁴⁺ system also consists of magnetic clusters with different sizes.     

Semi-invariants of canonical algebras

We describe the algebras of semi-invariants on the varieties of regular representations of canonical algebras. In particular, we show that these algebras are polynomial algebras or complete intersections. Received: 29 March 1999     

On the Distribution of Coefficients of Logarithmic Derivativesof L-Functions Attached to Certain Arithmetical Semigroups

 Under the Riemann Hypothesis for the classical Riemann zeta function, there exist infinitely many arithmetically non-isomorphic arithmetical semigroups with the property that one of the associated L-functions vanishes at . Moreover, there are no restrictions in the distribution of prime divisors of a given norm except an obvious one concerning the order of magnitude. Received 22 December 1997 in revised form 12 May 1998     

Structural studies of supported tin catalysts

Tin oxide was supported on aluminium oxide, titanium oxide, magnesium oxide and silicon oxide, and the resulting interactions between the components in the prepared samples and after reduction were characterized by Mössbauer spectroscopy. It was observed that in the oxide state, tin is present as SnO₂ on alumina, magnesia and silica, but on titania tin occupies Ti sites in the structure. After hydrogen treatment at high temperatures, tin is reduced from Sn(4) to Sn(2) on alumina and titania; it is reduced from Sn(4) to Sn(0) on silica, and is practically not reduced on magnesia. These results reveal the degree of interaction between tin and the different supports studied.     

Strategic Evaluation of the Traceless Staudinger Ligation for Radiolabeling with the Tricarbonyl Core

The traceless Staudinger ligation with its two variants is a powerful biorthogonal conjugation method not only for the connection of biomolecules, but also for the introduction of fluorescence- or radiolabels under mild reaction conditions. Herein, the strategic evaluation of the traceless Staudinger ligation for radiolabeling ^99mTc using the fac-[Tc(CO)₃]⁺ core is presented. A convenient and high-yielding three-step synthetic procedure of dipicolylamine-based phosphanols as ligands for the mild radiolabeling was developed. The labeling was accomplished using a tricarbonyl kit and a ^99mTc-pertechnetate generator eluate showing 87% radiochemical conversion. The respective rhenium-based, non-radioactive reference compounds were synthesized using (Et₄N)₂[Re(CO)₃Br₃] as precursor. All products were analyzed by NMR, MS, and elemental analysis. Additional XRD analyses were performed.     

Über die Oxidsilicate M2O[SiO4] der schweren Lanthanoide (M = Dy–Lu) im A‐Typ

On the Oxide Silicates M₂O[SiO₄] of the Heavy Lanthanides (M = Dy–Lu) with the A‐Type Structure By reacting the sesquioxides M₂O₃ of the heavy lanthanides (M = Dy–Lu) with SiO₂ and CsCl as flux (molar ratio 1 : 1 : 4; 700 °C, 7 d) in evacuated silica ampoules, it is possible to expand the series of lanthanide oxide silicates M₂O[SiO₄] with the A‐type structure (to date known with M = La–Tb) down to lutetium. The most important structural features, besides isolated ortho‐silicate anions [SiO₄]^4–, form oxygen‐centred (M³⁺)₄ tetrahedra, which are condensed to a two‐dimensional network [O(M1)_1/1(M2)_3/3)]⁴⁺ by sharing common edges and corners. The adaption of the structure (with coordination numbers of seven and nine, respectively, for the M³⁺ cations) to the smaller ionic radii of the heavy lanthanides is shown with help of X‐ray single‐crystal data. The influence of temperature on the stability of the products will be discussed.     

高分六号宽幅数据识别火烧迹地的光谱及指数分析

为探究利用高分六号卫星宽幅(GF-6 WFV)数据识别火烧迹地的适宜光谱波段和指数,选取2019年发生在我国内蒙古大兴安岭林区的三处雷击火形成的火烧迹地作为研究区,结合GF-6 WFV波段组成,选取归一化植被指数(normalized difference vegetation index,NDVI)、全球环境监测指数...