Concentration Effects Manifesting Themselves in the Luminescence of Tm3+ Ions in an Oxychloride Matrix

We investigated the luminescence characteristics of Tm³⁺ ions depending on their concentration in an oxychloride matrix. We measured luminescence spectra, luminescence excitation spectra, concentration dependences of the intensity and kinetics of various luminescence bands of rarex83/xxlarge8208.gif" alt="dash" align="MIDDLE" BORDER="0">earth ions of the visible and IR ranges at different excitation wavelengths. We carried out calculations of the concentration dependences of the quantum yield of luminescence: total and individual spectral bands. The crossx83/xxlarge8208.gif" alt="dash" align="MIDDLE" BORDER="0">relaxational nature of concentration effects in the luminescence of rarex83/xxlarge8208.gif" alt="dash" align="MIDDLE" BORDER="0">earth ions is discussed.     

Two‐Wave CO2 Laser with Loss Modulation in Both Channels

The nonlinear dynamics of a twox8k5x2p115165/xxlarge8208.gif" alt="dash" align="MIDDLE" BORDER="0">wave CO₂ laser with continuous pumping by an electric discharge and loss modulation in both channels is investigated theoretically. In modulation of losses with the same frequencies it is possible, by changing the shift of the phases of modulating signals, to monitor simply enough the amplitude, form, duration, and depth of modulation and also the repetition rate of radiation. Depending on the shift of phases, the maximum response can be concentrated in the lowx8k5x2p115165/xxlarge8208.gif" alt="dash" align="MIDDLE" BORDER="0">frequency region or propagate also to the region of high frequencies. If losses in both channels are modulated with different frequencies, a change in the relationship between these frequencies predominantly leads to a change in the shape, magnitude, and structure of response in the lowx8k5x2p115165/xxlarge8208.gif" alt="dash" align="MIDDLE" BORDER="0">frequency region of the amplitudex8k5x2p115165/xxlarge8208.gif" alt="dash" align="MIDDLE" BORDER="0">frequency characteristic (AFCh). In the highx8k5x2p115165/xxlarge8208.gif" alt="dash" align="MIDDLE" BORDER="0">frequency region of the amplitudex8k5x2p115165/xxlarge8208.gif" alt="dash" align="MIDDLE" BORDER="0">frequency characteristic, beginning from the peaks of the doubling of the vibration period, where inx8k5x2p115165/xxlarge8208.gif" alt="dash" align="MIDDLE" BORDER="0">phase modes of radiation are implemented, the response virtually does not change. Similar regularities are observed on change in the shift of phases.     

Lattice QCD calculations for the physical equation of state

In this report we consider the numerical simulations at finite temperature using lattice QCD data for the computation of the thermodynamical quantities including the pressure, energy density and the entropy density. These physical quantities can be related to the equation of state for quarks and gluons. We shall apply the lattice data to the evaluation of the specific structure of the gluon and quark condensates at finite temperature in relation to the deconfinement and chiral phase transitions. Finally we mention the quantum nature of the phases at lower temperatures.     

The comprehension, some problems and suggestions to symbolic vector method and some defenses for Gibbs' symbol

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Analytical Improvement in Measuring Formation Constants of Inclusion Complexes between β-Cyclodextrin and Phenolic Compounds

Inclusion complex formation betweensixteen para-substituted phenols andx28427247m0l4025/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin have been investigated in orderto establish Quantitative Structure AffinityRelationships. An analytical methodology is proposed,in order to obtain reliable evaluation of bindingaffinities. Potentiometry and circular dichroism havebeen applied to define experimental conditions and toconfirm postulated equilibriums. In addition, the useof algorithmic treatments and concentrationoptimisation to determine formation constants leads tocoherent values between ¹H NMR, direct UVSpectroscopy and the spectral displacement method. Theresults emphasise the contribution of van der Waalsinteractions, provided that no significant differencein the dipole of the molecule arises from thepara-substituent.     

A Solution and Solid State Study on 2-Hydroxypropyl-β-Cyclodextrin Complexation with Hyodeoxycholic Acid

Hyodeoxycholic acid (HDCA) isa 6-x283/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0"> dihydroxylated natural bile acid capable ofpreventing gallstone formation by reducing the bilecholesterol saturation. However, any attempt to enrichthe bile acid pool with HDCA have failed owing to thepoor solubility of the molecule. To resolve thebioavailability problems, the complexation of HDCAinto the HPx283/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">CD cavity was studied in solution(solubility methods, ¹³C- and ¹H-NMRspectroscopy and circular dichroism) and in the solidstate (IR spectroscopy, X-ray diffractometry andthermal analysis). According to the results, the HDCAinclusion took place with 1 : 1 stoichiometry. Theinfluence of different preparation methods of thesolid complex was evaluated for its potential use inappropriate pharmaceutical formulations to improve thebioavailability of HDCA.     

Crystal Structure and Molecular Modeling of 4,4′-Bi-4H-cyclopenta[def]phenanthrenylidene and Related Derivatives

The twisted pentafulvene, 4,4x136567h140q08/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-bi-4H-cyclopenta[def]phenanthrylidene, does not undergo oxidative electrocyclization to a semibuckminsterfullerene under photo-oxidative conditions. However, the use of standard dehydrogenating agents such as DDQ or tetrachloro-2,3-benzoquinone at 200°C resulted in partial oxidative electrocyclization and formation of a Diels–Alder adduct, respectively. The crystal structure of this Diels-Alder adduct was obtained and shown to possess C₂ symmetry. The crystal structure for 4,4x136567h140q08/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-bi-4H-cyclopenta[def]phenanthrylidene was also obtained and the molecular parameters differ slightly from what was previously reported for the same compound. Molecular modeling of this pentafulvene gave a twist angle matching the crystal structure. Similar modeling of related bifluorenylidene, bis-1,1x136567h140q08/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-indenylidenes and biscyclopentadienylidene gave twist angles which correlate with the computed heats of hydrogenation for the bridging alkene unit.     

Mouvement brownien et formule de Tanaka en analyse

In our previous paper [5], we have obtained a decomposition of x800/xxlarge8739.gif" alt="mid" align="MIDDLE" BORDER="0">fx800/xxlarge8739.gif" alt="mid" align="MIDDLE" BORDER="0">, where f is a function defined on R ^d , that is analogous to the one proved by H. Tanaka in the early sixties for Brownian martingales (the so-called x800/xxlarge8216.gif" alt="lsquo" align="BASELINE" BORDER="0">Tanaka formulax800/xxlarge8217.gif" alt="rsquo" align="BASELINE" BORDER="0">). The original proofs use purely analytic methods (e.g. the Calderón–Zygmund theory, etc.). In this paper, we give a new proof of our `Tanaka formula in analysisx800/xxlarge8217.gif" alt="rsquo" align="BASELINE" BORDER="0">, that is based on probabilistic arguments. The main tools here are Brownian motion, stochastic calculus and Burkholder–Gundy inequalities for martingales. These methods allow us to improve somewhat our previous results, by proving that some significant constants do not depend on the dimension d.     

A Conjecture of Hirschhorn on the 4-Dissection of Ramanujan's Continued Fraction

We show that two recently published conjectures by Hirschhorn concerning the 4-dissection of Ramanujan's continued fraction are correct.     

不同偏压下Zn1-xCdxSe-ZnSe超晶格室温电调制反射谱研究

首次研究了在室温和不同直流偏压下Zn_1-xCd_xSe-ZnSe超晶格结构的电调制反射谱(ER)的变化。当器件处于弱场范围时,随着电场的增加,ER谱的信号幅度增加,而线型不变;在强场区,随着电场的增加,ER谱的线型发生变化,激子跃迁能量红移,继续增加反向偏压出现来自于1c-2hh的禁戒跃迁,且其强度随反向偏压的增加迅速增加。不同偏压下组合超晶格结构的ER谱研究表明,势垒高度较低的超晶格结构中的激子较易受到电场的调制。