Investigation on microwave absorption capacity of nanocomposites based on metal oxides and graphene

Graphene and its nanocomposites were prepared via solution mixing process. Graphene based polymer nanocomposites were prepared by two step process. Firstly, graphene/poly(3-methyl thiophene)(PMT)/BaTiO₃ nanocomposite was prepared by in situ chemical oxidation polymerization technique. In the second step these nanocomposites were dispersed in thermoplastic polyurethane (TPU) matrix by solution blending process. All the four nanocomposites in TPU [30 % modified graphene (P1), 30 % Poly(3-methyl thiophene) (P2), 30 % graphene/PMT/BaTiO₃ (P3) and 15 % graphene/PMT/BaTiO₃ + 15 % Fe₃O₄ (P4)] were analyzed by different analytical techniques like X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). Microwave absorbing property was measured by Agilent vector network analyzer (ENA E5071C) in the X-band region (8–12 GHz). Microwave absorption result was interpreted with the help of complex permittivity and permeability of the prepared materials. Matching of both dielectric loss and magnetic loss is essential for an effective radar absorbing material (RAM). P1, P2, P3 and P4 showed the maximum return loss of ?14.37, ?9.3, ?30.02 and ?47.59 dB respectively. Thermal stability of the RAMs was determined by the help of thermogravimetric analysis (TGA) instrument. Among the all, P4 showed better thermal property. All results support their use as RAM in different field.     

Iodine speciation studies on Bunsen reaction of S–I cycle using spectroscopic techniques

Bunsen reaction is an important step of sulfur–iodine cycle for hydrogen production from thermochemical splitting of water. Polyiodide species generated during the separation process need to be identified for complete understanding of the mechanism involved. Speciation of these polyiodide species formed during Bunsen reaction can lead to better understanding of kinetics of the process. HIx species formed have been analyzed using UV–visible and Raman spectroscopic techniques. Peak corresponding to HI₃ species have been ascertained and their conversion to higher HI₅, HI₇ …… species has been observed.     

Growth and characterization of diamond particles,diamond films,and CNT-diamond composite films deposited simultaneously by hot filament CVD

It is important to understand the growth of CNT-diamond composite films in order to improve the inter-link between two carbon allotropes, and, in turn, their physical properties for field emission and other applications. Isolated diamond particles, continuous diamond thin films, and thin films of carbon nanotubes (CNTs) having non-uniformly distributed diamond particles (CNT-diamond composite films) were simultaneously grown on unseeded, seeded, and catalyst pre-treated substrates, respectively, using a large-area multi-wafer-scale hot filament chemical vapor deposition. Films were deposited for four different growth durations at a given deposition condition. The changes in surface morphology and growth behavior of diamond particles with growth duration were investigated ex situ using field emission scanning electron microscopy and 2D confocal Raman depth spectral imaging, respectively. A surface morphological transition from faceted microcrystalline nature to nanocrystalline nature was observed as a function of growth duration in the case of isolated diamond particles grown on both unseeded and catalyst pre-treated substrates. However, such a morphological transition was not observed on the simultaneously grown continuous diamond thin films on seeded substrates. 2D confocal Raman depth spectral imaging of diamond particles showed that the local growth of CNTs did not affect the growth behavior of neighboring diamond particles on catalyst pre-treated substrates. These observations emphasize the importance of surface chemical reactions at the growth site in deciding sp² or sp³ carbon growth and the final grain size of the diamond films.     

Applicability of Field Plate in Double Channel GaN HEMT for Radio-Frequency and Power-Electronic Applications

Silicon - In the present communication, for the first time, applicability of Field Plate (FP) for Double Channel (DC) AlGaN/GaNHEMT is demonstrated. Impact of design space parameters such as field...     

Investigation on DC/RF Performance of LG = 19 nm Heterogeneous Integrated Ga0.15In0.85As/InAs/Ga0.15In0.85As Composite Channel InP HEMT on Silicon Substrate for Future Beyond 5G and Quantum Computing Applications

Silicon - The RF/DC performances of LG = 19 nm heterogeneous integrated Ga0.15In0.85As/InAs/Ga0.15In0.85As composite channel based InP HEMT (high electron mobility transistor)...     

Gelatin‐carbohydrate phase‐separated hydrogels as bioactive carriers in vaginal delivery: Preparation and physical characterizations

The current study focuses on the alteration of properties of the gelatin hydrogels using polysaccharides (e.g., maltodextrin, dextran, and sodium carboxymethyl cellulose) for probable use in vaginal delivery of antimicrobials. The hydrogels were prepared by varying the proportions of gelatin and polysaccharides and were characterized by microscopy, mechanical testing, and impedance spectroscopy. Metronidazole (MZ), drug of choice for the treatment of bacterial vaginosis, was incorporated within the hydrogels. In vitro release studies of MZ from the hydrogels was studied in‐depth using modified Franz's diffusion cell. Antimicrobial efficiency of the MZ‐loaded hydrogels was tested against E. coli and B. subtilis. The results suggested that the incorporation of polysaccharides resulted in the phase‐separated hydrogels. The properties of the hydrogels was found be suitable for vaginal delivery. The drug release and antimicrobial efficiency from the hydrogels suggested that the developed hydrogels may be used for the delivery of antimicrobials in the vaginal lumen. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40445.     

达芬奇效应:简便的数字视频

数字视频将引发人们与电子产品交互方式的变革。实现数字视频不但复杂,而且费时费钱。而这一切难题在达芬奇技术面前全部烟消云散。     

Pesticides removal performance by low‐pressure reverse osmosis membranes

Pressure driven techniques (viz. reverse osmosis and nanofiltration) have the potentiality to remove the pesticides from water. The observations revealed that pesticides removal mostly depends upon the molecular weight (size exclusion) and hydrophobicity (log P) of the pesticides. Interfacial polymerization of m‐phenylene diamine (MPD) and trimesoyl chloride (TMC) on the polysulfone membranes impart the salt rejection property in it. It is shown that with the greater salt rejection property, the performance removal of pesticides also is in increasing trend. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3575–3579, 2006     

Computational modelling of industrial pulp stock chests

Agitated pulp stock chests are the most widely used mixers in pulp and paper manufacture. Stock chests are used for a number of purposes, including attenuation of high‐frequency disturbances in pulp properties (such as mixture composition, fibre mass concentration, and suspension freeness) and are designed using semi‐empirical rules based largely on previous experience. Tests made on both laboratory and industrial‐scale pulp chests indicate that they are subject to non‐ideal flows, including channelling and creation of dead zones. In the present work, a commercial computational fluid dynamic (CFD) software (Fluent) is used to model two industrial pulp stock chests. The first chest is rectangular, agitated using a single side‐entering impeller, and feeds a mixture of chemical pulps at 3.5% mass concentration (C_m) to a papermachine. The second chest has rectangular geometry, with a mid‐feather wall used to direct suspension flow through a U‐shaped trajectory past four side‐entering impellers. This chest is used to remove latency from a C_m = 3.5% thermomechanical pulp suspension ahead of stock screening. For CFD computations, pulp rheology was described using a modified Hershel–Buckley model. Steady‐state simulations were made corresponding to process conditions during mill tests. The calculated steady‐state flows were then used to determine the dynamic response of the virtual chests and then compared with experimental measurements and found to agree reasonably well. The computed flow fields provided insight into mixing processes occurring within the chests, showing cavern formation around the impellers (which reduced the agitated volume available for mixing). Mass‐less particle tracking, using the steady‐state flow field, gave insight into the stagnant regions and bypassing zones created in the vessels. This paper discusses difficulties encountered in characterising the mixing (both experimentally and computationally) and the limitations of the industrial data.