A New Practical Preparation of bis(Trimethylsilyl) Peroxide

Bis(trimethylsilyl) peroxide can be readily obtained by reaction of trimethylchlorosilane with the hexamethylenetetramine-hydrogene peroxide complex.     

Intracavity frequency doubling of Yb-doped fiber laser with 540–550 nm tuning

The intracavity doubling of a tunable Yb-doped fiber laser is studied. The phase effects are observed, analyzed and compensated. A smooth wavelength dependence of the second harmonic is obtained in the wavelength interval 540–550 nm. The second-harmonic output is greater than 300 mW at an LD pump power of 18 W.     

Frequency doubling and tripling in a Q-switched fiber laser

The frequency doubling and tripling in a Q-switched all-fiber laser are studied. It is demonstrated that the main limitations on the efficiency of the harmonic generation are related to the random polarization that is nonuniform with respect to axes, the asymmetric pulse shape with a flat trailing edge, and the significant spectral broadening of the multimode radiation of the fiber master oscillator in the fiber amplifier. The methods to increase the efficiency are proposed. For an IR pulse energy of about 0.3 mJ, duration of about 40 ns, and repetition rate of 1 kHz, the second- and third-harmonic pulse energies are greater than 60 and about 10 μJ, respectively.     

Differential reflectometry of FBG sensors in the wide spectral range

The paper presents a reflectometric technique for interrogation of multiple fiber Bragg grating (FBG) sensors based on conventional optical time domain reflectometry (OTDR). The method proposed rests on the differential measurement of FBGs’ response to a short probing laser pulse. Implementation of differential measurement principle using several reference FBGs allowed us to eliminate the susceptibility of the system to intensity fluctuations as well as to increase the measurement range as compared to the previous developments. The experimental threshold sensitivity amounted to ∼50 microstrain with the measurement range being defined by the number of reference FBGs and limited only by optical fiber tensile strength. Due to its simplicity, efficiency and usage of conventional OTDR equipment the proposed FBG interrogation technique can find a wide range of applications dealing with strain and temperature measurements.     

On the regularization mechanism for the periodic Korteweg–de Vries equation

In this paper we develop and use successive averaging methods for explaining the regularization mechanism in the the periodic Korteweg–de Vries (KdV) equation in the homogeneous Sobolev spaces Ḣ^s for s ≥ 0. Specifically, we prove the global existence, uniqueness, and Lipschitz‐continuous dependence on the initial data of the solutions of the periodic KdV. For the case where the initial data is in L₂ we also show the Lipschitz‐continuous dependence of these solutions with respect to the initial data as maps from Ḣ^s to Ḣ^s for s ∈(−1,0]. © 2010 Wiley Periodicals, Inc.     

Optimum advertising policy over time for subscriber service innovations in the presence of service cost learning and customers’ disadoption

On the theoretical side, this paper characterizes qualitatively optimal advertising policy for new subscriber services. A monopolistic market is analyzed first for which customers’ disadoption, discounting of future profits streams and a service cost learning curve are allowed. After characterizing the optimal policy for a general diffusion model, the results pertaining to a specific diffusion model for which advertising affects the coefficient of innovation that incorporates the disadoption rate are reported. The results of the theoretical research show that the advertising policy of the service firm in the presence of customers’ disadoption could be very different from the same when disadoption is ignored.On the empirical side, four alternative diffusion models are estimated and their predictive powers using a one-step-ahead forecasting procedure compared. The diffusion data analyzed are related to the Canadian cable TV industry. Empirical research findings suggest that the specific diffusion model considered above is not only of theoretical appeal but also of major empirical relevance.The analytical findings of the study are documented in six theoretical propositions for which proofs are provided in a separate Appendix. The results of a related numerical experiment together with the analytical findings pertaining to the competitive role of advertising are included. Managerial implications of the study together with directions for future research are also discussed.     

甘肃岷县不同生长年限当归药材的红外光谱分析

采用傅里叶变换红外光谱(FTIR)及其二阶导数谱对不同生长年限当归药材进行分析研究.结果表明,不同生长年限当归药材的红外图谱较为相似,仅从一维谱图上无法反映出不同生长年限当归药材的红外特征谱明显的异同,但通过二阶导数图谱中1771、1747、1712、1559、1514、1466、766、711cm-1和668cm-1处的峰型差异可发现不同生长年限当归药材之间的一些成分存在较明显的差异.由于生长时间不同,导致它们的化学成分存在差异,所以体现了各自的红外特征谱,其中第三年当归药材与第一年和第二年当归药材间差异较大.     

Ferrocenylalkyl azoles: bioactivity,synthesis, structure

The toxicity of ferrocenylethyl benzotriazole ( 1 ) and other ferrocene compounds including ferrocenylmethyl benzimidazoles ( 4,5,6,11 ), ferricenium salts ( 3,9,10 ) and ferrocenylmethyl adenine ( 7 ), was studied. All ferrocene complexes under investigation showed low or medium toxicities. On the basis of an earlier model of chemical carcinogenesis, the antitumor activity of ferrocenylalkyl azoles 1, 8 and ferricenium salts 9, 10 was studied in vivo in the so‐called sub‐capsular test on human tumors. This effectiveness was compared with that of cisplatin. A series of ferrocenylalkyl azoles were synthesized by interacting azoles either with α‐hydroxyalkyl ferrocenes FcC(OH)R₁R₂ in organic solvent in the presence of aqueous HBF₄ in quantitative yields or with trimethyl(aminomethyl)ferrocene iodide in an aqueous‐basic medium in good yields. The X‐ray determinations of molecular and crystal structures of α‐(1‐benzotriazolyl)ethylferrocene ( 1 ) and α‐(1‐naphthatriazolyl)ethylferrocene ( 12 ) were performed. Copyright © 2008 John Wiley & Sons, Ltd.     

Finite-element simulation of contact interaction with the use of concepts of contact pseudomedium mechanics

In the present paper, we analyze an algorithm for solving problems of elastic and elastoplastic contact between rigid deformable bodies taking into account the presence of additional media with various properties in the contact region. These may be nonlinear properties of surface rough layers and films. To take into account the influence of such layers, the finite-element scheme uses contact finite elements with nonlinear properties. We describe an algorithm developed for solving problems with various types of nonlinearities. Using the example of experimental studies described in detail in [1, 2], we identify the nonlinear properties of contact finite elements. Several examples are used to demonstrate the algorithm operating capability.