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71.
Shi W Zeng H Sahoo Y Ohulchanskyy TY Ding Y Wang ZL Swihart M Prasad PN 《Nano letters》2006,6(4):875-881
We describe and demonstrate a general strategy for engineering binary and ternary hybrid nanoparticles based on spontaneous epitaxial nucleation and growth of a second and third component onto seed nanoparticles in high-temperature organic solutions. Multifunctional hybrid nanoparticles that combine magnetic, plasmonic, and semiconducting properties and that are tunable in size and morphology can be realized, as demonstrated for combinations of Au, Fe3O4 and PbS or PbSe. The properties of each component within the hybrids can be modulated strongly by the conjugating component(s) aided by the coherent interfaces between them. 相似文献
72.
Humidity-Regulating Trays: Moisture Absorption Kinetics and Applications for Fresh Produce Packaging
Guido Rux Pramod V. Mahajan Manfred Linke Astrid Pant Sven Sängerlaub Oluwafemi J. Caleb Martin Geyer 《Food and Bioprocess Technology》2016,9(4):709-716
For packaged fresh produce, inappropriate high relative humidity (RH) levels and condensation of water vapour cause premature spoilage. Humidity-regulating trays were developed to solve this issue. They were made from a thermoformed multilayer structure: polyethylene (outside)/foamed hygroscopic ionomer (active layer) with 0 or 12 wt% NaCl/hygroscopic ionomer (sealing layer, inside). Moisture absorption kinetics of the humidity-regulating trays with 0 and 12 wt% NaCl (T-0 and T-12, respectively) was investigated under different RH conditions (76, 86, 96 and 100 %) at 13 °C for 16 days. Additional trays containing 7 g of distilled water were closed with a high barrier lidding film, and the headspace RH was continuously monitored as a function of time. As control, a polypropylene (control-PP) tray was used. Strawberries and tomatoes were used to test capability of the trays to regulate in-package RH. The amount of water absorbed by the T-0 and T-12 trays was 7.6 and 13.2 g, respectively. Active hygroscopic ionomer layer was effective in water vapour absorption, and the integration of NaCl into this active layer increased the water vapour absorption capacity of the tray. The Weibull model adequately described the moisture sorption kinetics of the individual packaging trays as a function of time. The headspace RH of trays covered with a lidding film was found to be 89.8, 99.6 and 100 % in the T-12, T-0 and control-PP trays, respectively. The T-12 trays containing fresh produce best regulated the in-package RH below 97 % and maintained overall quality, but at the expense of slightly higher product weight loss (2–3 wt% for strawberry, 1 wt% for tomatoes) compared to the control-PP trays (0.3–0.6 wt%). 相似文献
73.
Dongming Liu Yuhong Xiong Troy D. Topping Yizhang Zhou Chris Haines Joseph Paras Darold Martin Deepak Kapoor Julie M. Schoenung Enrique J. Lavernia 《Metallurgical and Materials Transactions A》2012,43(1):340-350
In this study, nanostructured Al 5083 powders, which were prepared via cryomilling, were consolidated using spark plasma sintering
(SPS). The influence of processing conditions, e.g., the loading mode, starting microstructure (i.e., atomized vs cryomilled powders), sintering pressure, sintering temperature, and powder particle size on the consolidation response and
associated mechanical properties were studied. Additionally, the mechanisms that govern densification during SPS were discussed
also. The results reported herein suggest that the morphology and microstructure of the cryomilled powder resulted in an enhanced
densification rate compared with that of atomized powder. The pressure-loading mode had a significant effect on the mechanical
properties of the samples consolidated by SPS. The consolidated compact revealed differences in mechanical response when tested
along the SPS loading axis and radial directions. Higher sintering pressures improved both the strength and ductility of the
samples. The influence of grain size on diffusion was considered on the basis of available diffusion equations, and the results
show that densification was attributed primarily to a plastic flow mechanism during the loading pressure period. Once the
final pressure was applied, power law creep became the dominant densification mechanism. Higher sintering temperature improved
the ductility of the consolidated compact at the expense of strength, whereas samples sintered at lower temperature exhibited
brittle behavior. Finally, densification rate was found to be inversely proportional to the particle size. 相似文献
74.
The purpose of this work was to study the transition from the smooth to the wavy stratified flow regime for various pipe inclination angles and liquid physical properties. The accurate characterization of both the structure of the gas-liquid interface and the flow field inside the liquid layer can improve our physical understanding of the mechanisms involved in the evolution of waves in stratified gas-liquid flow. To study the influence of liquid properties on the mechanisms promoting wave formation, several liquids are used (i.e., water, Tween®, and aqueous-glycerin solutions). The experiments are conducted in a 24 mm i.d. pipe for various inclination angles (1–9°) with respect to the horizontal position. Liquid layer thickness time records are acquired using a parallel-wire conductance technique from which mean layer thickness, rms, and power spectra of the fluctuations as well as wave celerities are calculated. Measurements of the axial velocity component in the liquid layer using laser-Doppler anemometry are also reported. Statistical analysis of such local liquid velocity data in conjunction with the liquid layer characteristics reveals a strong interplay between wave evolution at the interface and the flow field development inside the liquid layer. Finally, results of numerical calculations using a CFD code are obtained to facilitate data interpretation. 相似文献
75.
Ken-Tye Yong Yudhisthira Sahoo Mark T. Swihart Paul M. Schneeberger Paras N. Prasad 《Topics in Catalysis》2008,47(1-2):49-60
Seeded growth of gold nanorods (NRs) has been accomplished in a micellar medium containing mixed surfactants or a high salt
concentration. Cetyl trimethylamoniumbromide (CTAB) forms micelles upon which the growth of rod shaped gold nanoparticles
occurs. AgNO3 is introduced into the growth solution to enhance the formation of NRs. The roles of non-ionic surfactants such as Tween
and Triton, and of electrolytes such as sodium chloride and potassium chloride have been examined. As the concentration of
these additives in the growth solution is increased, the aspect ratio of the NRs increases to a critical limit, after which
it decreases again. Upon carefully controlling the content of Triton X-100 or Tween 20 in the growth solution, these non-ionic
surfactants assisted in fine-tuning the shape of gold NRs (e.g. rectangular or “dogbone”). The growth pattern of the NRs fits
into the model of a soft template formed by the mixture of CTAB and non-ionic surfactants. 相似文献
76.
Yun-A Seo Hem Raj Pant R. Nirmala Ji-Hui Lee Kyung Geun Song Hak Yong Kim 《Journal of Porous Materials》2012,19(2):217-223
Highly porous Poly (ε-caprolactone; PCL) microfibers were successfully fabricated by collecting the fibers into a water bath
during electrospinning. The morphology of the fibers collected with and without the water bath was investigated. We observed
that altering the pH of the water bath affected both the fiber diameter and the size of pores on the fibers. Acidic or basic
condition was found to be more favorable than neutral conditions for the formation of well-porous fibers. The morphology and
pore size of the microfibers were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The
average diameter of the fibers and the pore size on the surface of the microfibers were found to be 12–14.5 and 0.3–0.7 μm,
respectively. The crystallinity and thermal properties of the PCL mats were investigated by DSC. This highly porous nature
of the microfibers makes PCL less crystalline and increases the surface to volume ratio of the mat. Therefore, the PCL mat
obtained by water bath electrospinning may be more effective for tissue scaffolds and drug delivery than the mat obtained
without water bath. 相似文献
77.
R. K. Gupta Bhanu Pant P. P. Sinha 《Transactions of the Indian Institute of Metals》2014,67(2):143-165
Among the high temperature materials γ + α2 Ti aluminide is the most promising material, which has unique characteristics of low density coupled with high temperature properties. However, the low room temperature ductility of the alloy has limited its commercial application. Many studies have been carried out on this alloy to understand the phase transformation and role of alloying elements. Several processing methodologies have been attempted and advantages of various routes have been explored. However, poor ductility at room temperature is still a concern. In the present paper a thorough review of relevant studies has been carried out and viable route for industrial processing has been suggested. This paper includes theoretical concepts behind limited ductility of alloy at room temperature and its processing difficulty through the conventional methods. Modification in binary Ti aluminide alloy through alloying addition, selection of suitable processing route and heat treatment are noted as important areas which can provide a practical solution for this alloy to bring it to industrial processing and application. 相似文献
78.
C. ShekharPant Mada S. S. N. M. Santosh Shaibal Banerjee Pawan K. Khanna 《Propellants, Explosives, Pyrotechnics》2013,38(6):748-753
The paper reports the energization of Hydroxyl‐Terminated Polybutadiene (HTPB) by functionalizing explosophore NO2 over the HTPB backbone, resulting in the formation of conjugated nitro‐alkene derivative of HTPB. A convenient, inexpensive and efficient “one pot” procedure of synthesizing Nitro‐Functionalized Hydroxyl‐Terminated Polybutadiene (Nitro‐HTPB) is reported. The reaction was carried out with sodium nitrite and iodine. To retain the unique physico‐chemical properties of HTPB, functionalization by NO2 group was restricted to 10 to 15 % of double bonds. The Nitro‐HTPB was characterized by FTIR, 1H NMR, VPO, DSC, TGA etc. The polymer has shown good thermal stability for practical applications. The kinetic parameters for the decomposition of Nitro‐HTPB at 150–300 °C were obtained from non‐isothermal DSC data. 相似文献
79.
Anupma Gupta Ankush Kansal Paras Chawla 《International Journal of Electronics》2013,100(12):1814-1828
Bio-telemetry is an advanced area of research that enables the transmission of biomedical parameters from human body to external monitoring device. Wearable antennas showing robust performance are attaining attention for RF bio-telemetry. A square ring-shaped ground antenna with a truncated patch is investigated for dual mode, on-body and off-body communication. The proposed antenna structure is analysed and optimised on a multi-layered flat tissue phantom. Proposed design resonates at 2.6 GHz with |S11| ?22 dB and at 5.2 GHz with |S11| ?35 dB on the phantom gel. Wide bandwidth of 520 MHz (2.33–2.85 GHz) and 620 MHz (4.78–5.4 GHz) efficiently covers ISM, LTE and WLAN bands and enables the antenna to withstand frequency detuning due to different body postures. Antenna shows maximum radiation efficiency of 15% at 2.45 GHz band when placed close to the tissue. Low specific absorption rate (SAR) value of 0.459/0.523/0.303 W/Kg at 2.45/2.6/5.2 GHz ensures the tissue safety. 相似文献
80.
Pant P. Roy R.K. Chattejee A. 《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》2001,9(2):390-394
We demonstrate a novel algorithm for assigning the threshold voltage to the gates in a digital random logic complementary metal-oxide-semiconductor (CMOS) circuit for a dual-threshold voltage process. The tradeoff between static and dynamic power consumption has been explored. When used along with device sizing and supply voltage reduction techniques for low power, the proposed algorithm can reduce the total power dissipation of a circuit by as much as 50% 相似文献