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81.
The results on changes in the apparent hydrodynamic diameter (Dh) of micelles in a solution containing 5% of a moderately hydrophobic/hydrophilic triblock PEO-PPO-PEO copolymer in the presence
of several hydroxyl compounds at 23 °C from dynamic light scattering (DLS) are reported. Distribution plots show micelles
with hydrodynamic diameter ~17 nm and low polydispersity (<0.1) except at low concentrations where a unimer peak (~ 4 nm)
was also noticed. These additives increase/decrease the micelle size and show micellar transition depending upon their hydrophilicity/hydrophobicity.
The results are discussed in terms of the effect of the additives on altering water structure and their partitioning in micelle.
Short chain alcohols (C1–C3) increase solvation of PEO and thus increase micelle hydrodynamic size while higher alcohols, initially reduce Dh due shrinkage of PEO followed by micellar growth at higher concentrations. Among αω-alkanediols, C2 and C4 diols increase micelle size by immobilizing water sphere around the micelles whereas higher diols form wicket like structures
and reside in palisade layer. Isomeric hexanediols (1,2; 1,5; 2,5 and 1,6) alter micelle size in different ways depending
on their hydrophobicity. In C6EO
m
(m = 0, 1, 2), as the number of EO group increases, it becomes more hydrophilic and increases Dh at higher concentration. Addition of a hydrophobic triblock copolymer leads to unfavorable mixing with a moderately hydrophobic/hydrophilic
triblock copolymer which results in increase in size, while the addition of a hydrophilic counterpart increases the average
hydrodynamic size and follows appearance of unimer peak. 相似文献
82.
Vinod N. DhageM.L. Mane M.K. BabrekarC.M. Kale K.M. Jadhav 《Journal of Alloys and Compounds》2011,509(12):4394-4398
The nanocrystalline Cr3+ substituted barium hexaferrite having generic formula BaFe12−xCrxO19 (where x = 0.00, 0.25, 0.50, 0.75, and 1.00) samples were synthesized by sol-gel auto-combustion technique. The precursors were prepared by using stoichiometric amounts of Ba2+, Fe3+ and Cr3+ nitrate solutions with citric acid as a chelating agent. The metal nitrate to citric acid ratio was taken as 1:2 while pH of the solution was kept at 8. The thermal decomposition of nitrate-citrate gels of as-prepared powder was investigated by TG/DTA. The as-prepared powder of BaFe12−xCrxO19 was sintered at 900 °C for 8 h. The sintered powder was characterized by XRD, EDAX, SEM and VSM technique. The pure barium hexaferrite shows only single phase hexagonal structure, while for the samples at x = 0.25, 0.50, 0.75 and 1.00 shows α-Fe2O3 peaks with M-phase of barium hexaferrite. The lattice parameters (a and c) decreases with increase in chromium content x. The particle size obtained from XRD data is in the range of 30-40 nm which confirms the nanocrystalline nature of the samples. The magnetic properties were investigated by means of vibrating sample magnetometer (VSM) technique. The saturation magnetization (Ms), remanence magnetization (Mr), coercivity (Hc) and magneton number (nB) decreases with increase in chromium content x. 相似文献
83.
Chemical looping reforming (CLR) is a new technology for syngas generation. The theoretical process design aspects of syngas generation using CLR of isooctane (gasoline) are studied in this paper to assess its ability for fuel processor development for solid oxide fuel cells. The fuel processor operating conditions for maximum syngas generation at thermoneutral conditions are determined in this study using nickel oxide as oxygen carrier for different inputs of oxygen carrier within the temperature range of 600–1,000 °C at 1 bar pressure. The thermoneutral temperatures for the dual reactor fuel processor were calculated using the hot product gas stream and exothermic CLR process enthalpy to completely balance the endothermic process requirements. The thermoneutral point of 879.5 °C (NiO input of 7 moles) delivered maximum syngas (13.92 moles) using lowest amount of air (26.13 moles) in the process was found to be the most suitable thermoneutral temperature for the fuel processor operation. The novel fuel processor design can also be used for other fuels and oxygen carriers. 相似文献
84.
SiO2 thin films are in high demand for wide range of applications including microelectronics, optoelectronics, solar energy conversion, photocatalysis, and self-cleaning coatings. The performance of thin film is strongly influenced by surface properties like surface roughness, thickness, morphology, wetting behavior, and thermal stability. In these applications, the SiO2 sols were prepared using tetraethylorthosilicate as a source of SiO2 and deposited on 100?×?40?×?2?mm3 glass slide using dip-coating method for 2?min and calcined at 250?°C for 30?min. The SiO2 thin films were obtained using DTAB, SDS, and Tween 20 (Tw 20) surfactants with the thickness of 36.92, 47.15, and 52.39?nm, respectively. Surface morphology was studied with AFM and surface roughness was depicted with 0.9528, 3.6534, and 0.9294?nm. Contact angle measurements have been performed with goniometer to evaluate the wetting behavior of the film. The contact angle of 58.01°, 48.40°, and 37.88° was observed with SDS, DTAB, and Tw 20 film, respectively. The SiO2 thin films with SDS showed more surface roughness and water repelling ability when compared to DTAB and least with Tw 20. 相似文献
85.
Paresh H. Salame Om Prakash A. R. Kulkarni 《Journal of the American Ceramic Society》2013,96(7):2184-2189
The pristine layered cuprate Pr2CuO4 samples of >95% density were fabricated as thin disks. The samples, analyzed by X‐ray diffraction and Scanning electron microscopy, showed clean T′‐type phase with Rietveld refined lattice parameters a = b = 3.95805(±5) Å and c = 12.2262(±5) Å. The measured dielectric properties of the Pr2CuO4 ceramics, in the temperature range ?100°C–150°C and frequencies (ν) 0.1 Hz–1 MHz, showed extremely high εr′ > 104 (above ?30°C), and dissipation (tan δ = εr′′/εr′) between 0.1 and 5 (for 500 Hz ≤ ν ≤ 1 MHz, and ?100 ≤ T ≤ 150°C). The ac conductivity of Pr2CuO4 ceramics ranged between 10?6 and 10?3 Scm?1 for the measured frequencies and temperatures, and showed frequency‐dependent double power law behavior akin to a modified Jonscher's power law. 相似文献
86.
In this paper, we depart from the literature on electricity consumption–real GDP in that for the first time we examine the reaction of real GDP to shocks in electricity consumption. To achieve this goal, we use the structural vector autoregressive (SVAR) model and examine the impact of electricity consumption shocks on real GDP for the G7 countries. We find that except for the USA, electricity consumption has a statistically significant positive impact on real GDP over short horizons. This finding implies that except for the USA, electricity conservation policies will hurt real GDP in the G7 countries. 相似文献
87.
Mg–Ni multilayers and Ni-rich Mg thin films were deposited by electron gun and pulsed laser deposition, respectively. Samples were submitted to thermal treatment in deuterium or hydrogen atmosphere at 423 K and 105 Pa pressure to promote the metal to hydride phase transition.The H chemical bonding in the multilayer samples, after annealing in H2 atmosphere, was examined by Fourier transform infrared spectroscopy: the obtained spectra suggest that the samples with the Mg:Ni=2:1 atomic ratio contain the Mg2NiH4 phase while the samples with lower Ni concentration contain both the MgH2 and the Mg2NiH4 phases.The effect of the Ni additive on the stability of the deuteride phase was studied by thermal desorption spectroscopy (TDS). The TDS spectra of the single-phase Mg2NiD4 samples show a TDS peak at 400 K. The TDS spectra of the two-phase samples show both the D2 desorption peak at 400 K and a second peak at higher temperature that we attributed to the dissociation of the MgD2 phase. The high-temperature peak shifts to lower temperatures by increasing the Ni content.It is suggested that in the two-phase samples, the lattice volumes having the Mg2Ni structure resulting from the dissociation of the Mg2NiD4 phase reduce the thermodynamic stability of the MgD2 phase. 相似文献
88.
Methods of bio-functionalize silicon nitride involve process steps to convert it into an oxynitride via plasma implantation
techniques. Such methods can potentially damage microstructures such as cantilevers. In this paper, we report successful bio-functionalization
of Hotwire CVD silicon nitride-based piezo-resistive cantilevers without any oxygen plasma treatment. Process to fabricate
such structures and to bio-functionalize them is discussed in detail. 相似文献
89.
Jelani Griffin Anant Kumar Singh Dulal Senapati Eumin Lee Kevin Gaylor Jeanette Jones‐Boone Paresh Chandra Ray 《Small (Weinheim an der Bergstrasse, Germany)》2009,5(7):839-845
The hepatitis C virus (HCV) is a single‐stranded (ss) RNA virus that is responsible for chronic liver diseases, such as cirrhosis, end‐stage liver disease, and hepatocellular carcinoma. Driven by the need to detect the presence of the HCV viral sequence, herein it is demonstrated for the first time that the nonlinear optical (NLO) properties of gold nanoparticles can be used for screening and quantifying HCV RNA without any modification, with excellent detection limit (80 pM ) and selectivity (single base‐pair mismatch). The hyper‐Rayleigh scattering (HRS) intensity increases 25 times when label‐free, 145‐mer, HCV ss‐RNA is hybridized with 400 pM target RNA. The mechanism of HRS intensity change is discussed with experimental evidence for a higher multipolar contribution to the NLO response of gold nanoparticles. 相似文献
90.
提出了将J2EE和CADRBA的集成应用于基于HDF4格式的遥感数据发布系统的思想,介绍了HDF4文件格式,阐述了该应用的必要性;分析了该模型的体系结构以及客户端、应用服务器端、CDRBA组件和数据库的设计过程;最后展望了该模型的应用前景。 相似文献