Novel and chemoselective one-pot synthesis of 4-arylidene-2-phenyl-5(4H)-oxazolones starting from benzyl alcohols promoted by [(C14H24N4)2W10O32]-[bmim]NO3

Abstract  

A new and practical promoter system for one-pot, efficient, chemoselective synthesis of 4-arylidene-2-phenyl-5(4H)-oxazolones using [(C₁₄H₂₄N₄)₂W₁₀O₃₂]-[bmim]NO₃ under solvent-free conditions is described. The present work opens up a new and ecofriendly synthetic route to Erlenmeyer–Pl?chl adducts from primary benzyl alcohols in a one-pot operation.     

Solvent‐free synthesis of 2H‐pyrans: One‐pot reactions of dithiocarbamates,alkyl propiolates,and isocyanides

A novel, convenient, and an efficient approach to the synthesis of 2H‐pyrans has been reported based on the multicomponent reaction. Solvent‐free condition for the reaction of dithiocarbamates, alkyl propiolates and isocyanides lead to the formation of 2H‐pyrans in good yields. In these reactions, synthesis of 2H‐pyrans is possible based on the one‐pot reaction and without using any catalyst. The mild reaction conditions and high yields of the products exhibit the good synthetic advantage of these methods. J. Heterocyclic Chem., lpar;2011).     

Reaction kinetics of a novel thermoset nanocomposite: the glycerol diglycidyl ether/3,3-dimethylglutaric anhydride/nano-Al2O3 system

Abstract  

The curing behavior of the glycerol diglycidyl ether/3,3-dimethylglutaric anhydride/nano-alumina system was examined using a dynamic differential scanning calorimetry technique. The activation energy of the system was calculated using the Kissinger, Ozawa, Barrett, and two-parameter Sestak–Berggren models. Under the assumption of a constant activation energy and an autocatalytic mechanism, the activation energy, frequency factor, and total order of reaction were computed. The theoretical reaction rate was also calculated and compared to the experimental results. Good agreement was seen between the experimental and calculated data confirming the autocatalytic mechanism. The effect of triethylamine concentration on the reaction rate was clarified using the Barrett method. Fourier transform infrared spectroscopy (FT-IR) spectroscopy was used to verify the formation of internal ester groups. Scanning electron microscopy (SEM) and X-ray mapping analyses revealed that the nanofiller was homogeneously distributed in the continuous phase.     

Molecular structure and theoretical studies of new stable phosphorus ylides derived from trialkyl phosphites

The reaction between dialkyl acetylenedicarboxylates and NH heterocyclic compounds in the presence of trialkyl phosphite leads to stable phosphorus ylide derivatives in good yields. The x‐ray crystallographic data and theoretical study show that there is a resonance between two bonds of C₉P₁ and C₉₁O₉₁ in phosphorous ylide 4c . This compound crystallizes in the triclinic system, space group ( ), with the following unit cell parameters: a = 8.7522(3)Å, b = 8.8513(5)Å, c = 18.3469(5)Å, α = 99.1220(10)°, β = 90.954(2)°, γ = 118.792(2)°, Z = 2, and V = 1222.72(9)ų. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 22:36–43, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20653     

Performance Improvement in Fiber-Optic Spectrometers Using Photonic Crystal Fibers

Abstract

Resolution enhancement of a high-speed fiber-optic spectrometer is investigated in this article. The operation of these types spectrometers is based on conversion of the spectral-domain signal into the time domain by a dispersive element. A photonic crystal fiber is used as a dispersive fiber in this spectrometer. Resolution enhancement of considered spectrometer with photonic crystal fibers is studied. The fiber loss and length minimization in this spectrometer are obtained. Simulation results show that an increase in resolution will cause a decrease in the speed of the spectrometer. Trade offs between resolution and speed are studied.     

Novel Design Method for Single-Mode Bend-Insensitive Fiber Appropriate for Fiber-to-the-Home Application

Abstract

A proposal for a new single-mode optical fiber design technique with ultra-low bending loss applicable in fiber-to-the-home operation is presented. The suggested design method is based on reverse problem engineering, which evaluates the refractive index profile. The most remarkable feature of this methodology is designing a bend-insensitive fiber without core radius and mode field diameter reductions. The designed structures exhibit ultra-low bending loss and high effective area simultaneously. Meanwhile, the residual stress of the designed structures is small due to gradual variation of the refractive index in the core region. Simulation results show a bending loss of 4.3 × 10^?4 dB/turn at 1.55 μm for a single turn of 5-mm radius.     

Light extraction efficiency enhancement in organic light emitting diodes based on optimized multilayer structures

The main focus of this study is to improve the light extraction efficiency, as well as directionality of organic light emitting diodes (OLEDs) using multi-layer structures between Indium tin Oxide (ITO) and glass layers in a typical OLED. In conventional OLEDs, only about half of the light generated in the emission zone can reach to the glass substrate due to refractive index mismatch in ITO (n = 1.8?i0.01)/glass (n = 1.51) interface. The main attempt is to reduce the share of total internal reflection (TIR) and hence, the effect of different structures such as Thue-Morse and Fibonacci have been investigated and optimized with suitable layer thickness and materials based on Transfer Matrix Method (TMM). The most effective Multi-layer structures have been added to conventional OLED and have been analyzed the extraction efficiency using Finite Difference Time Domain (FDTD) method. Results show large enhancement of extraction efficiency (about 40%) in ITO/glass interface. Using this idea and applying micro-lenses array to glass substrate at the same time, one can get even higher extraction efficiency in OLED. The interesting aspect of this project is its easy fabrication process in order to commercialize the product with highest extraction efficiency and low fabrication cost.     

M-type atomic basic cell as a low intensity long wavelength infrared photodetector

A five-level atomic system in M-type configuration has been proposed in this article as a long-wavelength infrared photodetector cell. Coherent population trapping and electromagnetically induced transparency (EIT) is appeared in this kind of atomic structure. In order to overcome the dark current noise problem in the long-wavelength infrared photodetectors, we utilize quantum interference phenomena between the electromagnetic fields and interpret the incoming long-wavelength to short-wavelength detection range, where the dark current noise is not critical. The proposed M-type-arranged atomic system, have high performance in lower intensities of long-wavelength IR which is more interesting from high-sensitive photodetector point of view.     

Linear frequency-doubling in dual Mid-IR-wavelength quantum cascade laser active region

In this paper we have proposed a novel quantum cascade laser active region design to obtain a dual-mid-IR-wavelength laser which is capable of frequency-doubling (13.77–6.88 μm) without utilizing nonlinear processes in two coupled shallow and deep quantum well structures. Optimized design of the active region leads to higher dipole matrix elements and thus higher laser performances. This method can be used to design laser structures with different frequency ratios.     

Novel and Highly Effective Method for the Trimethylsilylation of Alcohols and Phenols with Hexamethyldisilazane (HMDS), Catalyzed by I2 Generated in situ Using Fe(NO3)3⋅9 H2O/NaI under Heterogeneous and Neutral Conditions

Structurally diverse alcohols and phenols were trimethylsilylated in a clean and efficient reaction with hexamethyldisilazane (HMDS) based on the use of I₂ generated in situ from Fe(NO₃)₃?9 H₂O/NaI. The reaction occurs very rapid in good‐to‐high yield in CH₂Cl₂ at room temperature, and the use of toxic and corrosive molecular I₂ is avoided.