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101.
A series of poly(arylene ether)s ( 7a–7f ) were successfully synthesized by aromatic nucleophilic substitution reactions of imidoaryl biphenol (5), 4,9‐bis‐(4‐hydroxy‐phenyl)‐2‐phenyl‐benzo[f]isoindole‐1,3‐dione with six different trifluoromethyl substituted bisfluoro monomers ( 6a–6f ). The weight‐average molar masses of the polymers were up to 280 kD as measured by GPC. These poly(arylene ether)s exhibited glass transition temperatures up to 361°C in DSC. These polymers showed very high thermal stability up to 558°C for 10% weight loss under synthetic air in TGA. Except 7d–7f, remaining polymers 7a–7c were soluble in a wide range of organic solvents. Transparent thin films of these polymers cast from DCM or NMP exhibited tensile strengths up to 75 MPa and elongation at break up to 41% depending on their exact repeating unit structures. These poly(arylene ether)s showed cut‐off wavelength in between 400 and 450 nm except 7d and water absorption were in the range of 0.4 to 0.6%. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
102.
T. P. Ahammed Shabeer V. T. Gajbhiye Suman Gupta K. M. Manjaiah Eldho Varghese 《Polycyclic Aromatic Compounds》2013,33(4):452-467
Water treatment process involving simultaneous action of adsorption on different nano and organo-modified nano-clays followed by coagulation-flocculation by alum and poly aluminium chloride (PAC) has been evaluated for the removal of PAHs (naphthalene, acenaphthalene, phenanthrene, fluoranthene, anthracene, and pyrene) from water. When clay minerals along with alum and PAC were used for treatment, 37.4–100.0% removal of PAHs was observed compared to 20–38% removal using normal water treatment process with either alum or alum + PAC. The effectiveness of clay minerals for removal of PAHs followed the order (P < 0.05): halloysitenano-clay (HN-clay) < normal bentonite (NB-clay) < hydrophilic nano-bentonite (HNB-clay) < nano-montmorillonite modified with dimethyl dialkyl amine (DMDA-M-clay) ≈ nano-montmorillonite modified with octadecylamine and aminopropyltriethoxysilane (ODAAPS-M-clay) ≈ nano-montmorillonite modified with octadecylamine (ODA-M-clay) in combination with alum + PAC. The modified treatment process (alum + PAC + clay minerals), where water was initially treated with clays followed by normal process of coagulation (alum + PAC), was found to be the most effective method with maximum removal for ODAAPS-M-clay (97.7–100.0%) which is at par wih ODA-M (97.0–100.0%), and DMDA-M-clay (94.8–100%). The removal of PAHs varied in the order: naphthalene ≈ acenaphthalene > anthracene ≈ pyrene > phenanthrene > fluoranthrene. The treatment combination having the maximum removal capacity was also used eficiently for the removal of PAHs from natural and fortified natural water. This article demonstrated adsorption-coagulation integrated system has the potential to remediate PAHs polluted water. 相似文献
103.
Suman Mukherjee John Federici Paulo Lopes Miguel Cabral 《Journal of Infrared, Millimeter and Terahertz Waves》2013,34(9):539-555
For the past few decades there has been tremendous innovation and development of Terahertz (THz) science and imaging. In particular, the technique of 3-D computed tomography has been adapted from the X-Ray to the THz range. However, the finite refractive index of materials in the THz range can severally refract probing THz beams during the acquisition of tomography data. Due to Fresnel reflection power losses at the boundaries as well as steering of the THz beam through the sample, refractive effects lead to anomalously high local attenuation coefficients near the material boundaries of a reconstructed image. These boundary phenomena can dominate the reconstructed THz-CT images making it difficult to distinguish structural defect(s) inside the material. In this paper an algorithm has been developed to remove the effects of refraction in THz-CT reconstructed images. The algorithm is successfully implemented on cylindrical shaped objects. 相似文献
104.
21st Century is treated as the century for highly branched macromolecules, because of their unique structural architecture and outstanding performance characteristics, in the field of polymer science. In the present study, castor oil-based two hyperbranched polyurethanes (HBPUs) were synthesized via A2 + B3 approach using castor oil or monoglyceride of the castor oil as the hydroxyl containing B3 reactant and toluene diisocyanate (TDI) as an A2 reactant along with 1,4-butane diol (BD) as the chain extender and poly(?-caprolactone) diol (PCL) as a macroglycol. The adopted ‘high dilution and slow addition’ technique offers hyperbranched polymers with high yield and good solubility in most of the polar aprotic solvents. Fourier transforms infra-red spectroscopy (FTIR) and nuclear magnetic resonance (NMR) analyses confirmed the chemical structure of synthesized polymers, while wide angle X-ray diffraction (WXRD) and scanning electron microscope (SEM) resulted the insight of their physical structures. The degree of branching was calculated from 1H NMR and found to be 0.57 for castor oil based hyperbranched polyurethane (CHBPU), while it was 0.8 for monoglyceride based hyperbranched polyurethane (MHBPU). The studies showed that MHBPU and CHBPU exhibited tensile strength 11 MPa and 7 MPa, elongation at break 695% and 791%, scratch hardness 5 kg and 4.5 kg, gloss 84 and 72, respectively. Thermal properties like thermo stability, melting point, enthalpy, degree of crystallinity and glass transition temperature (Tg); and chemical resistance in different chemical media were found to be almost equivalent for both the polyurethanes. The measurements of dielectric constant and lost factor indicated that both the HBPUs behave as dielectric materials. Thus the synthesized HBPUs have the potential to be used as advanced surface coating materials. 相似文献
105.
JamesM. Takacs Suman Layek Hector Palencia RossN. Andrews 《Advanced Synthesis \u0026amp; Catalysis》2005,347(15):1937-1942
An optimized palladium‐N‐heterocyclic carbene catalyst system effects the palladium‐catalyzed bisdiene cyclization‐trapping with phenol at the 0.01% catalyst loading level with a TON of 7.6×103 and TOF of 280 h−1, values much higher than typically found for this and related carbocyclizations. The reaction scales well and the trans‐substituted six‐membered ring product is obtained in excellent yield on a 10‐mmole scale without further optimization of the catalyst system or reaction conditions. 相似文献
106.
Dipankar Chatterjee Suman Chakraborty 《Metallurgical and Materials Transactions B》2005,36(6):743-754
The turbulent flow inside a laser-generated molten pool is investigated by an adapted large-eddy simulation (LES) model that
incorporates physical considerations pertaining to the solid-liquid phase change. A single-domain, fixed-grid enthalpy-porosity
approach is utilized to model the phase-change phenomena in the presence of a continuously evolving solid/liquid interface.
The governing transport equations are simultaneously solved by employing a control-volume formulation, in conjunction with
an appropriate enthalpy-updating closure scheme. To demonstrate the performance of the present model in the context of phase-change
materials processing, simulation of a typical high-power laser melting process is carried out, where effects of turbulent
transport can actually be realized. It is found that the present LES-based model is more successful in capturing the experimental
trends, in comparison to the k-ε-based turbulence models often employed to solve similar problems in contemporary research investigations. 相似文献
107.
108.
Complex impedance analysis of polycrystalline Pb2Bi3LaTi5O18, prepared by a high-temperature solid-state reaction technique has been carried out. XRD analysis indicated the formation
of a single-phase orthorhombic structure. Impedance plots were used as a tool to analyse the behaviour of the sample as a
function of frequency and temperature. The bulk resistance has been observed to decrease with rise in temperature showing
a typical negative temperature coefficient of resistance (NTCR) type behaviour like that of semiconductors. The ac impedance
studies revealed the presence of grain boundary effect at 450°C and showed polydispersive non Debye-type dielectric relaxation.
The frequency dependent ac conductivity at different temperatures indicated that the conduction process is thermally activated
process. The activation energy for bulk (0.67 eV) and grain boundary (0.73 eV) was estimated from the temperature variation
of respective conductivities. 相似文献
109.
In India, an estimated 80% of children are infected with tubercle bacillus by 10 years of age. Elimination of tuberculosis depends on finding all infectious patients and providing them with curative chemotherapy. Pulmonary tuberculosis--the most common form in children--is diagnosed when a child presents with fever, prolonged cough, weight loss, recurrent wheezing, or chest infection; the chest x-ray is suggestive of tuberculosis; and three or more of the following conditions exist: 1) Mantoux test result of 10 mm or more, 2) tuberculosis lymphadenitis by fine needle aspiration cytology, 3) grade III malnutrition, 4) no BCG vaccination, 5) positive family history of tuberculosis, and 6) recent history of pertussis or measles. Recommended, for children with pulmonary tuberculosis, is a regimen of isoniazid, rifampicin, and pyrazinamide daily for 2 months, followed by the first two drugs daily for an additional 4 months. The poor tuberculosis cure rates in most developing countries reflect patient non-compliance with treatment regimens. 相似文献
110.
Ferrari M. Ferrari V. Marioli D. Taroni A. Suman M. Dalcanale E. 《IEEE transactions on instrumentation and measurement》2006,55(3):828-834
A novel oscillator circuit with automatic capacitance compensation (ACC) capability has been coupled with quartz-crystal-microbalance (QCM) sensors coated with quinoxaline- and pyrazine-bridged cavitands to detect aromatic and chlorinated compounds in water. With double-side immersed 10-MHz crystals coated with the quinoxaline cavitand, the detection of toluene in deionized water was possible down to concentrations of a few parts per million. The ACC oscillator advantageously provides the simultaneous measurement of the sensor resonant frequency, damping, and value of the compensated parallel capacitance. This enabled observing that the analyte sorption in the cavitand coating not only brings about a mass uptake but also an increase of losses and, apparently, a rise in the coating average permittivity. 相似文献