Asymmetric patchy Ag/Cu Janus nanoparticles (NPs) were synthesized via a “seed-mediated” approach. This is the first report of synthesis of nanometer sized metal-based Janus NPs without using complicated methods. Selective adsorption of the surfactant onto the seed NPs leads to the formation of Janus type structure. Subsequently the reduction potential of Ag+/Ag0 and Cu2+/Cu0 systems directs the formation of the “patch”. The patchy Janus NPs show significant antifungal activity towards a potent rice pathogen thus offering the prospect of future application in crop protection. 相似文献
Multiferroic composites of spinel ferrite and ferroelectric xCoFe2O4 – (1-x)Na0.5Bi0.5TiO3 (with x = 0.10,0.30,0.50) were efficiently prepared by standard solid state reaction mechanism. X-ray diffractometer was used to analyze crystal structure of the prepared composites. The observed XRD patterns of the composites comprise peaks of both the phases i.e. ferrite and ferroelectric, with no sign of secondary peaks. Rietveld refinement of XRD data further confirms the coexistence of these two phases with cubic (Fd3m) and rhombohedral (R3c) symmetry corresponding to ferrite and ferroelectric phase respectively. The 3-dimensional overview of crystal structure of pure CoFe2O4 and Na0.5Bi0.5TiO3 and of composite 0.50CoFe2O4?0.50Na0.5Bi0.5TiO3 is generated by using refined parameters. The dielectric constant (ε´) and dielectric loss (tanδ) values were recorded as a function of frequency ranging from 100?Hz to 7?MHz and at different temperatures. Both ε´ and tanδ follow dispersion pattern at lower frequencies while show frequency independent behavior at higher frequencies. The magnetic evaluation carried by analyzing M-H hysteresis loop reveals the ferrimagnetic characteristics of these composites. The highest value of magnetic moment is 1.12μB observed for composite 0.50CoFe2O4 – 0.50Na0.5Bi0.5TiO3. Magnetoelectric (ME) voltage coefficient (α) was also demonstrated to observe the interaction between ferrite and ferroelectric phases. The highest value of α (72.72μV/Oe cm) is obtained for low ferrite composition 0.10CoFe2O4 – 0.90Na0.5Bi0.5TiO3, which suggests the dependence of magnetoelectric response on the resistivity of the composites. 相似文献
The filterbank transceiver structure for fractal modulation has been developed. It has been shown that the transceiver complexity
is comparable to that of OFDM.The use of orthogonal space time block codes (OSTBC) in conjunction with Fractal Modulation
(STFrM) in the presence of frequency selective fading channels has also been considered. An L scale fractal modulation and coherent demodulation effectively converts a frequency selective channel into L flat fading channels per information symbol with random scale gains. The analysis of the proposed scheme in terms of bit
error rate has been performed. A diversity order of mTmRL can be achieved, where mT,mR are the number of transmitters and receivers, respectively. This increase in diversity order in comparison with that achieved
for the OFDM case is at a cost of lower spectral efficiency. However the spectral efficiency of STFrM can be improved R times by the use of multiplicity ‘R’ multiwavelets. 相似文献
The dielectric properties of Mg substituted Ni-Li spinel ferrites synthesized by sol-gel auto combustion process have been studied using impedance measurements in the frequency range from 10 Hz to 10 MHz and in the temperature range from 310 K to 473 K. The effect of frequency, temperature and composition on dielectric constant (?′), dielectric loss (tan δ) and conductivity (σ) has been discussed in terms of hopping of charge carriers between Fe2+ and Fe3+ ions. The electrical modulus formulism has been employed to study the relaxation dynamics of charge carriers and the results indicate the presence of non-Debye type of relaxation in the present ferrites. Similar values of activation energies for dc conduction (Edc) and for conductivity relaxation (EM″) reveal that the mechanisms of electrical conduction and dielectric polarization are same in these ferrites. A single ‘master curve’ for normalized plots of all the modulus isotherms observed for a given composition indicates the temperature independence of dynamical process for charge carriers. The saturation magnetization and coercivity have been calculated from the hysteresis loop measurements and show striking dependence on the composition. 相似文献
Queens and workers are not morphologically differentiated in the primitively eusocial wasp, Ropalidia marginata. Upon removal of the queen, one of the workers becomes extremely aggressive, but immediately drops her aggression if the
queen is returned. If the queen is not returned, this hyper-aggressive individual, the potential queen (PQ), will develop
her ovaries, lose her hyper-aggression, and become the next colony queen. Because of the non-aggressive nature of the queen,
and because the PQ loses her aggression by the time she starts laying eggs, we hypothesized that regulation of worker reproduction
in R. marginata is mediated by pheromones rather than by physical aggression. Based on the immediate loss of aggression by the PQ upon return
of the queen, we developed a bioassay to test whether the queen’s Dufour’s gland is, at least, one of the sources of the queen
pheromone. Macerates of the queen’s Dufour’s gland, but not that of the worker’s Dufour’s gland, mimic the queen in making
the PQ decrease her aggression. We also correctly distinguished queens and workers of R. marginata nests by a discriminant function analysis based on the chemical composition of their respective Dufour’s glands. 相似文献
AbstractIn the present work, the effect of high-energy ball milling (HEBM) of starting precursors of hydroxyapatite (Ca10(PO4)6(OH)2)/HA system on the processing temperature, morphological, mechanical, and electrical properties are highlighted. Calcination and sintering of HA system were carried out in microwave furnace. XRD study confirmed the evolution of HA phase and EDX analysis confirmed Ca/P ratio ~1.65. Grain size of HA samples, synthesized by using microwave-assisted HEBM technique was found to be in the order of 54–75?nm. Enhanced dielectric and mechanical properties were obtained in HA samples. 相似文献
In this present work, we report that phosphotungstic acid provides a simple, efficient and environmentally benign route is a two-component one-pot domino Knoevenagel-type condensation/Michael reaction between 4-coumarin derivative and an aldehyde in water as a solvent in shorter duration with high yields.相似文献
Eutectoid steels, which are traditionally used as rails in railway systems, are prone to corrosion, especially in coastal environments. In order to minimize this problem, four new rail steel compositions, with different combinations of microalloying elements Cu, Cr, Ni and Si, were designed and processed as per the thermomechanical schedule for normal rail steel processing in industry. Corrosion behavior of the rail steels were studied by weight loss measurement after immersion test and Tafel polarization in freely aerated 3.5 % NaCl. The rust obtained after immersion test were characterized by Fourier transform infrared spectroscopy (FTIR). Corrosion rate obtained weight loss measurement was similar for all the rail steels. γ-FeOOH (lepidocrocite) and δ-FeOOH were identified as the major rust phases from the FTIR spectra of the rail steels. The relative absorption intensities of these rust phases were similar for all the rail steels. Corrosion rates calculated from Tafel polarization tests were similar for all the rail steels. The corresponding free corrosion potentials were also similar for all the rail steels. The zero corrosion potential obtained from Tafel polarization of Cu-Mo, Cr-Mn, Cu-Ni, Cr-Cu-Ni and Cr-Cu-Ni-Si rail steels was more noble compared to C-Mn and Cu-Si rail steels indicating better corrosion resistance of these alloys. The importance of conducting alternate wetting and drying test has been emphasized. 相似文献
A mobile ad hoc network (MANET) is a collection of wireless mobile nodes that can communicate without a central controller or fixed infrastructure. Due to node mobility, designing a routing protocol to provide an efficient and suitable method to route the data with less energy consumption, packet drop and to prolong the network lifetime has become a challenging issue in MANETs. In MANETs, reducing energy consumption and packet loss involves congestion control and load balancing techniques. Thus, this paper introduces an efficient routing technique called the multipath load balancing technique for congestion control (MLBCC) in MANETs to efficiently balance the load among multiple paths by reducing the congestion. MLBCC introduces a congestion control mechanism and a load balancing mechanism during the data transmission process. The congestion control mechanism detects the congestion by using an arrival rate and an outgoing rate at a particular time interval T. The load balancing mechanism selects a gateway node by using the link cost and the path cost to efficiently distribute the load by selecting the most desirable paths. For an efficient flow of distribution, a node availability degree standard deviation parameter is introduced. Simulation results of MLBCC show the performance improvements in terms of the control overhead, packet delivery ratio, average delay and packet drop ratio in comparison with Fibonacci sequence multipath load balancing, stable backbone-based multipath routing protocol and ad hoc on demand multipath distance vector routing. In addition, the results show that MLBCC efficiently balances the load of the nodes in the network.