The cyclodimerisation of 3-methyl-2-butenenitrile

3-Methyl-2-butenenitrile (1) cyclodimerised on treatment with lithium diisopropylamide in dimethoxyethane at temperatures between ?78°C and 0°C to 3-amino-4-cyano-1,5,5-trimethyl-1,3-cyclohexadiene (2) the structure of which was established by acid hydrolysis to the known 4-cyano-1,5,5-trimethyl-1-cyclohexene-3-one (3).     

Conical parametric scattering of a single extraordinary beam in BaTiO3 crystal

In this paper, the parametric scattering of a single extraordinary polarized beam of laser in BaTiO₃ photorefractive crystal has been investigated experimentally and theoretically. The resulting pattern consists of beam fanning, isotropic ring, and anisotropic one. Among all parts of scattering pattern, isotropic ring has not been studied as much as beam fanning and anisotropic ring, and there still are some differences in reports about it. Therefore, the study has mainly focused on this part. In this experimental configuration, isotropic ring is just visible in positive angles although the other parts of parametric scattering pattern can be visible from behind and in front of the crystal. In addition to steady state pattern in forward and backward directions, its transient behavior with the rotation of crystal has been studied. The results of experiments have been analyzed carefully, and their theoretical explanations have been presented based on the standard theory of parametric scattering in photorefractive crystals. It has been shown that this configuration corresponds to the so called parametric B-process scattering.     

Self-chemical ionization of diethylzinc

The self-chemical ionization of diethylzinc is examined by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry and semiempirical molecular orbital calculations. Electron impact of diethylzinc neutral produces the radical cation, C(4)H(15)Zn(+) (m/z x 122), which reacts further with the neutral (C(2)H(5))(2)Zn to give the following product ions: Zn(+) (m/z x 64), C(2)H(5)Zn(+) (m/z x 93), C(4)H(9)Zn(+) (m/z x 121), C(4)H(11)Zn(2)(+) (m/z x 187), and C(6)H(15)Zn(2)(+) (m/z x 215). To determine the structure and pathways for production of these ions, monoisotopic (12)C(4)H(15)(64)Zn(+), (64)Zn(+) and (12)C(2)H(5)(64)Zn(+) were individually isolated and reacted with the neutral background. We also performed semiempirical molecular orbital calculations (ZINDO/1). The molecular orbital calculations and experimental data are consistent in predicting that the ethyl group on the diethylzinc cation carries the positive charge. Copyright 1999 John Wiley & Sons, Ltd.     

Synthesis,optical, dielectric,thermal and mechanical properties of a nonlinear optical amino acid crystal: Bis-glycine hydrobromide

A semi organic material Bis-glycine hydrobromide (C₄H₁₁N₂O₄⁺Br⁻) has been synthesized by slow solvent evaporation technique. The grown crystal was subjected to single crystal X-ray diffraction studies and its crystal parameters were confirmed. The FTIR analysis confirms the presence of various functional groups present in the title compound. The Kurtz powder second harmonic generation test shows that the crystal is a potential candidate for optical second harmonic generation. The UV–vis spectrum reveals the transparency of the crystal and enumerates the direct band gap energy of the material. The dielectric constant and the dielectric loss were studied as a function of frequency. The thermal studies indicate that the material is thermally stable up to 290 °C. The hardness number was calculated to be 110 kg/mm² from the Vicker's microhardness test.     

怀孕期头发中一些元素含量的变化趋势

用同步辐射激发X射线荧光分析,对11个产妇怀孕期间头发内一些元素含量的变化趋势进行了测量,在各自对比的基础上,得到了一些结果。     

Multifunctional zig-zag-shaped D-π-A-π-D emitters with high conjugation extent for blue FOLEDs and host for PHOLEDs

We have synthesized zig-zag shaped, meta- and para-linked D-π-A-π-D blue emitters, m-BTPAPy and p-BTPAPy based on a non-symmetrical connection strategy of two identical π-conjugated groups. The phenanthrimidazole moiety coupled to pyridine via naphthyl spacer by para- and meta-linking modes. Both m-BTPAPy (T_d/T_g, °C: 564/281) and p-BTPAPy (T_d/T_g, °C: 502/246) exhibit excellent thermal stability and can form a stable amorphous film. Changing the connection strategy from para to meta mode, m-BTPAPy shows deep blue emission with CIE (0.15, 0.07). The highly twisted m-BTPAPy exhibit higher Photoluminescence quantum yield (PLQY)_s/f of 0.98/0.85 than p-BTPAPy (0.95/0.80) owing to the suppression of intermolecular stacking. The non-doped blue device (BOLEDs) with multifunctional m-BTPAPy/p-BTPAPy show external quantum efficiency (EQE) of 7.12/5.12% with small roll-off efficiency of 1.68/2.14%, power efficiency (PE) of 5.92/5.42 lm/W, the luminance of 58675/76234 cd/m², and current efficiency (CE) of 6.12/5.86 cd/A. The non-doped device using m-BTPAPy/p-BTPAPy as both emitting and electron-transporting material exhibit luminance of 40671/49539 cd/m², CE of 5.01/5.08 cd/A, PE of 4.68/4.76 lm/W, EQE of 6.12/4.81%, roll-off efficiency of 1.63/1.87%, and CIE (0.15, 0.10)/(0.15, 0.11). These bipolar materials with high triplet energy were employed as hosts in green and red PhOLEDs. The green (m-BTPAPy: Ir(ppy)₃)/red device (m-BTPAPy: Ir(MDQ)₂(acac)) exhibit maximum EQE of 29.85/20.09%, luminance of 79523/42412 cd/m², CE of 78.62/27.56 cd/A, and PE of 72.36/23.86 lm/W, and CIE (0.33, 0.60)/(0.65,0.33).     

Nuclear orbiting and anomalies in nuclear reactions

In this paper, we report our measurements of back-angle oxygen and carbon particle yields from ¹⁶O+⁸⁹Y, ¹²C+⁹³Nb reactions forming the same compound nucleus ¹⁰⁵Ag at the same excitation energy and spin distribution. We find anomalously large oxygen yield and entrance channel dependence at high excitation energies from ¹⁶O+⁸⁹Y reaction implying formation of a dinuclear orbiting complex. Possible connection between nuclear orbiting and fast fission is also discussed.     

In silico targeting PAD4 for the treatment of rheumatoid arthritis

Structural Chemistry - Rheumatoid arthritis (RA) is an autoimmune disorder that causes chronic inflammation with periodic bursts of activity in multiple synovial joints which lead to irreversible...