Synthesis of Alkyllysophospholipid Analogues with Readily Functionalized 1-O-Alkyl Side Chain

Synthesis of alkyllysophospholipid analogues 5a and 5b are described. These lipids have imide functional group attached on the terminal of 1-O-alkyl side chain suitable for further manipulations. Our approach features the use of mesylate 8 in which the mesyl group serves both as protecting group and electrophile.     

Evaluation of runaway thermal reactions of di-<Emphasis Type="Italic">tert</Emphasis>-butyl peroxide employing calorimetric approaches

Di-tert-butyl peroxide (DTBP) is an organic peroxide (OP) which has widespread use in the various chemical industries. In the past, thermal runaway reactions of OPs have been caused by their general thermal instability or by reactive incompatibility in storage or operation, which can create potential for thermal decomposition reaction. In this study, differential scanning calorimetry was applied to measure the heat of decomposition reactions, which can contribute to understand the reaction characteristics of DTBP. Vent sizing package 2 was also employed to evaluate rates of increase for temperature and pressure in decomposition reactions, and then the thermokinetic parameters of DTBP were estimated. Finally, hazard characteristics of the gassy system containing DTBP, specifically with respect to thermal criticality, were clearly identified.     

Azine Synthesis via Nitrogen-Nitrogen Bond Formation

Imine anions, generated by reaction of nitrites with organometallic reagents, are dimerized to form symmetrical azines through the use of CuI and t-butyl peroxybenzoate.     

Numerical study on InGaAsN/GaAs multiple-quantum-well laser with GaAsP and GaAsN barriers

In this work, the multiple-quantum-well InGaAsN laser structures with indirect-GaAsP and direct-GaAsN barriers are investigated by using LASTIP simulation program. We vary the quantum-well number, from 1 to 5, to find appropriate barrier material for InGaAsN laser structures. The simulation results show that InGaAsN laser structure has higher characteristic temperature regardless of what quantum-well number is if the indirect-GaAsP barrier is utilized. Furthermore, for InGaAsN laser structure, the usage of indirect-GaAsP barrier is beneficial for reducing the threshold current when the quantum-well number is from 1 to 2 and the usage of direct-GaAsN barrier is beneficial for reducing the threshold current when the quantum-well number is from 3 to 5.     

Central wavelength tunable mechanism for temperature compensatedpackage of fiber Bragg gratings

The central wavelength of fiber Bragg grating (FBG) must be located in the specified channel band of wavelength division multiplexer (WDM) in optical communication network. Furthermore, the central wavelength also must he stable in the ambient temperature. A temperature compensated fixture Is therefore essential for the application of FBG. By the strength of materials, a theoretical model of the fully temperature compensated fixture can he derived for zero shift of central wavelength of FBG in ambient temperature. Besides, a microtunable mechanism for the pre-pulling force on the FBG is synthesized to adjust the central wavelength to a certain channel band. By this tunable mechanism one can calibrate effectively and efficiently the FBG in mass production of FBG based products     

Perturbed-TEM analysis of transmission lines with imperfectconductors

A perturbed-transverse electromagnetic (TEM) approach to studying the detailed current distribution and the propagation constant of a multiconductor transmission line system with imperfect conductors is discussed. The perturbed fields are derived assuming that the fields outside the conductors are TEM waves of the corresponding lossless system and those inside the conductors satisfy the transverse magnetic (TM) modal equations. These fields are then inserted into a perturbational formula to obtain the propagation constant of the lossy system. The current distribution and the propagation constant (which clearly illustrates the loss mechanism due to the skin effect and the proximity effect) of a lossy two-wire system are presented as an example     

Investigation of EMI-induced noise spectrum in an enhancement-type MOSFET

This paper models the time domain and frequency domain characteristics of the noise spectrum of a MOSFET device under varying EMI conditions. The theoretical results are compared with experimental measurements. Both sets of results reveal that the magnitude of the EMI-induced noise is governed by the pulse height, the output load, the parasitic capacitance, the interference frequency and the interference amplitude. Furthermore, it is shown that a higher interference amplitude or frequency increases the harmonic noise. The theoretical method presented in this paper provides a convenient means of evaluating the EMI effects and signal-to-noise ratio (SNR) of MOSFETs and similar wavelength devices.     

A switching power amplifier with feedback for improving total harmonic distortion

A high efficiency and low distortion and switching power amplifier is proposed. We use feedback to reduce the total harmonic distortion (THD) and the DC output bias current. The experimental results show that the proposed circuit has 0.24% total harmonic distortion and 91% power efficiency while the DC output bias current is 12 μA at 1.5 V supply voltage.     

Saccharomyces cerevisiae oxidosqualene‐lanosterol cyclase: A chemistry–biology interdisciplinary study of the protein's structure–function–reaction mechanism relationships

The oxidosqualene cyclases (EC 5.4.99‐) constitute a family of enzymes that catalyze diverse cyclization/rearrangement reactions of (3S)‐2,3‐oxidosqualene into a distinct array of sterols and triterpenes. The relationship between the cyclization mechanism and the enzymatic structure is extremely complex and compelling. This review covers the historical achievements of biomimetic studies and current progress in structural biology, molecular genetics, and bioinformatics studies to elucidate the mechanistic and structure–function relationships of the Saccharomyces cerevisiae oxidosqualene‐lanosterol cyclase‐catalyzed cyclization/rearrangement reaction. © 2008 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 8: 302–325; 2008: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.20157