Eco-friendly sustainable materials provide an appealing template to replace contemporary synthetic-nonrenewable resource-based materials while maintaining the acceptable material properties to meet the performance requirements. Here, a layer-by-layer (LBL) self-assembly technique was used for fabricating multilayer composite films using all bio-based polymers/polysaccharides, i.e. cationic guar gum (CGg), carboxylated cellulose nanocrystals (cCNCs) and hydroxypropyl methylcellulose (HPMC). A five layered composite film was fabricated by depositing polymeric layers as follows: CGg→cCNCs→HPMC→cCNCs→CGg. The structural analysis of (CGg/cCNCs/HPMC)5 L multilayered composite films indicated the existence of electrostatic interaction as well as H-bonding between polymeric layers that resulted in homogenous, dense and compact film surface with improved smoothness and strength properties. As compared to pure CGg film, the (CGg/cCNCs/HPMC)5 L multilayered composite films showed improved tensile strength (84.8?% increment) and modulus (29.19?% improvement). Importantly, the deposition of HPMC layer contributed in achieving multilayer composite films with more flexible behavior (46.55?% improvement in elongation at break). Furthermore, owing to the high transparency (89.5?% transmittance), appreciable gas and oil barrier performance and resistance to various solvents (e.g. acetone, THF and DMAc), these multilayer films are promising candidates for various applications including renewable/sustainable packaging materials.
Chirped probe pulse femtosecond coherent anti‐Stokes Raman scattering (CPP fs‐CARS) thermometry was performed at 5 kHz in a hydrogen jet diffusion flame with an air co‐flow. Measurements were performed at different heights and radial locations within the jet diffusion flame, up to 16 nozzle exit diameters downstream (x/d = 16). The near‐nozzle measurements were characterized by large, organized, buoyancy‐driven instabilities that become more chaotic at the downstream locations x/d ≥ 4. The diffusion flame results highlight temperature fluctuations characteristic of the buoyancy‐driven Kelvin–Helmholtz‐type instability and provide new insights into the transient structure of these flames. At some measurement locations, the time‐varying temperatures ranged from 300 K to nearly 2400 K. The CPP fs‐CARS signal intensity is a factor of approximately 1000 times lower at 2400 K compared with 300 K. A dual‐channel detection system was used to increase the dynamic range of the CARS measurements. The determination of temperature from the single shot spectra is discussed in detail. Laser and detection system parameters were determined from CPP fs‐CARS spectra obtained from a near‐adiabatic laminar calibration flame apparatus. The temperature precision of the system was determined from these calibration measurements and was found to be better than 2.0% at 2200 K. The influence of an instrument response function on spectral fitting parameters is systematically assessed. Published 2015. This article is a U.S. Government work and is in the public domain in the USA. 相似文献
Uniform sized silica and zirconia mixed titania samples were prepared in presence of a surfactant (CETAB) using controlled hydrolysis of corresponding metal alkoxides. Photocatalytic activity towards reduction of lead and cadmium metal in aqueous solution was evaluated both in UV and visible light in a 100 ml capacity reactor. In particular mixing of 10 wt% silica with titania not only increases the surface area of the material but also increases the photocatalytic activity in UV light. Whereas mixing of zirconia with titania proved to be beneficial for visible light reaction. However, addition of hole scavenger increases the activity many folds and complete removal of Pb(2+) and Cd(2+) was possible in 60 min of reaction using synthesized catalysts. Among all the organic hole scavengers used, sodium formate is found to be the most active one. Interestingly quite high metal removal (89%) is also observed in presence of visible light within 60 min of reaction. Thus the above study indicates that the presence of certain oxides in low quantity (10 wt%) with titania can facilitates the photocatalytic process selectively in UV as well as visible light. 相似文献
A novel synthetic pathway to approach 3-(imino)isoindolin-1-ones by the Co-catalyzed cyclization reaction of 2-bromobenzamides with carbodiimides has been developed. This catalytic reaction can tolerate a variety of substituents and provide corresponding products in moderate yields for most cases. According to the literature, the reaction mechanism is proposed through the formation of a five-membered aza-cobalacycle complex, which carries out the following reaction subsequence, including nucleophilic addition and substitution, to furnish the desired structures. 相似文献
Kinetics and Catalysis - The current study focuses on the photocatalytic oxidation of benzyl alcohol in acetonitrile under air bubbling conditions comparing titania-based materials, Cu–MOF,... 相似文献
The breaking of the N=8 shell-model magic number in the 12Be ground state has been determined to include significant occupancy of the intruder d-wave orbital. This is in marked contrast with all other N=8 isotones, both more and less exotic than 12Be. The occupancies of the [FORMULA: SEE TEXT]orbital and the [FORMULA: SEE TEXT], intruder orbital were deduced from a measurement of neutron removal from a high-energy 12Be beam leading to bound and unbound states in 11Be. 相似文献
In this paper, the dynamics of a particle placed on a thin circular plate carrying circumferential harmonic travelling wave is studied. Coulomb friction is used to model the particle–surface interaction. Distinct regions on the plate surface are identified where either of the three phases of particle motion, namely jumping, sliding and sticking, occurs. Also, the effect of wave frequency and the plate geometry on these regions is studied. Interestingly, there exists an optimum plate thickness for which the region of sliding is maximum. At certain wave frequencies, from the numerical simulations within sticking and sliding regions, it is observed that the average particle motion spirals inwards towards the plate centre. Such an average motion is observed whenever the particle is placed initially with a zero velocity relative to the plate surface. The Gedanken experiments discussed herein provide cogent explanations to all the observed average (slow) dynamics and are also found to be useful in predicting the slow dynamics of the particle a priori, that is, before the actual numerical simulations. The particle’s velocity couples the radial and tangential sliding friction components and is found to be the key physical feature that explains the observed behaviour. Also, it is observed that the plate surface excited by circumferential travelling waves can provide acoustic lubrication to a particle by reducing the limiting force required to move it relative to the surface. The methods discussed in this paper can be extended to study the dynamics of a group of particles (granular materials) and extended rigid bodies, interacting with such surface waves.