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排序方式: 共有620条查询结果,搜索用时 15 毫秒
41.
Multimedia Tools and Applications - The world of electronics in particularly in the field of image processing, numerous distinguishable and noteworthy contributions have been made available.... 相似文献
42.
Vinayak Dakre D. R. Peshwe S. U. Pathak Ajay Likhite 《Transactions of the Indian Institute of Metals》2017,70(9):2381-2387
Austempered ductile iron (ADI) is known to have a good combination of mechanical properties due its unique ausferrite microstructure. The strength of ADI is mainly a function of the austempering temperature and the stability of ausferrite matrix. To increase the stability of the ausferritic matrix, two stage austempering processes was developed. During this investigation, in the Ist step, ductile iron specimens were austenitized at 900 °C for 60 min followed by quenching to 250 °C in salt bath. In the IInd step, after quenching at 250 °C, the salt bath was gradually heated to 350 °C, 400 °C and 450 °C respectively where specimen were soaked for 120 min. The tensile strength and impact strength were evaluated according to ASTM standards. The results were compared with that obtained by conventional austempering process by quenching directly into salt bath at 400 °C for 120 min. Both tensile and impact strength were found to have improved by two step austempering process. During Ist stage of austempering, martensite was observed while during IInd stage of austempering microstructures revealed acicular ferrite and carbon stabilized austenite. The fractographic examination revealed mixed type of fracture mode and intergranular fracture was seen under SEM. It was further observed that the tensile strength decreased whereas the impact strength increased with IInd stage of austempering temperature. 相似文献
43.
Melt‐Centrifuged (Bi,Sb)2Te3: Engineering Microstructure toward High Thermoelectric Efficiency 下载免费PDF全文
Yu Pan Umut Aydemir Jann A. Grovogui Ian T. Witting Riley Hanus Yaobin Xu Jinsong Wu Chao‐Feng Wu Fu‐Hua Sun Hua‐Lu Zhuang Jin‐Feng Dong Jing‐Feng Li Vinayak P. Dravid G. Jeffrey Snyder 《Advanced materials (Deerfield Beach, Fla.)》2018,30(34)
Microstructure engineering is an effective strategy to reduce lattice thermal conductivity (κl) and enhance the thermoelectric figure of merit (zT). Through a new process based on melt‐centrifugation to squeeze out excess eutectic liquid, microstructure modulation is realized to manipulate the formation of dislocations and clean grain boundaries, resulting in a porous network with a platelet structure. In this way, phonon transport is strongly disrupted by a combination of porosity, pore surfaces/junctions, grain boundaries, and lattice dislocations. These collectively result in a ≈60% reduction of κl compared to zone melted ingot, while the charge carriers remain relatively mobile across the liquid‐fused grains. This porous material displays a zT value of 1.2, which is higher than fully dense conventional zone melted ingots and hot pressed (Bi,Sb)2Te3 alloys. A segmented leg of melt‐centrifuged Bi0.5Sb1.5Te3 and Bi0.3Sb1.7Te3 could produce a high device ZT exceeding 1.0 over the whole temperature range of 323–523 K and an efficiency up to 9%. The present work demonstrates a method for synthesizing high‐efficiency porous thermoelectric materials through an unconventional melt‐centrifugation technique. 相似文献
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46.
K. M. Sundqvist A. Phipps A. V. Dixit B. Sadoulet 《Journal of Low Temperature Physics》2014,176(3-4):188-193
This work describes the transport and capture processes of electrons and holes in ultrapure germanium \(\langle 100 \rangle \) at low temperature and low electric field. Dynamic space-charge effects are responsible for the most significant systematics of the Cryogenic Dark Matter Search. To understand the relationship of transport dynamics to space charge evolution, it is important that we understand charge carrier transport under these nonequilibrium operating conditions. Here, we present measured data and a consistent model of electron and hole dynamics and capture. A charged and a neutral capture probability for both electrons and holes appears to explain the multiple, field-dependent power laws observed in data. This offers a quantitative understanding why germanium crystals operating under these conditions should “neutralize” when grounded, but accrue space charge while under bias. 相似文献
47.
In the present study Zn1−xMnxO (x = 0, 0.05 and 0.1) nanoparticles (NPs) have been synthesised in aqueous solution phase at mild reaction temperature 100 °C in moderate alkaline medium (pH = 9.5), and the role of external additives; like sodium dodecyl sulphate and manganese chloride on the morphology and size of the products has been explored on the basis of transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectral analyses data. ZnO hexagonal nano-plates, core–shell like spherical/ellipsoidal Zn0.95Mn0.05O structures and thin sheets, thorn/needle mixed shaped Zn0.9Mn0.1O structures have been observed in TEM and SEM images. Zn(OH)2 formed in moderate alkaline medium, converted to Zn(II) hydroxo complex ions on dissolution, which further recrystallizes to produce wurtzite ZnO at 100 °C. From XRD and EDX analysis, successful doping of Mn2+ ions at the Zn2+ sites in ZnO host has been proved. In the photoluminescence spectra, the observed blue shifts in NBE peaks and decrease of emissions intensity on Mn doping have thoroughly been discussed in the present investigation. 相似文献
48.
Adki VS Shedbalkar UU Jagtap UB Jadhav JP Bapat VA 《Journal of hazardous materials》2011,191(1-3):150-157
Phytoremediation is considered as an effective viable alternative to remediate the contaminated sites, industrially hazardous chemicals and other toxic pollutants. This bioremediation option offers a safe, cheap and eco friendly alternative to existing physical and chemical remediation technologies as well as other biological sources. The wall paint preservatives consist of several harmful and carcinogenic compounds causing serious environmental concerns. In the present study, an actively growing Blumea malcolmii Hook cell suspensions were established successfully on MS+CM (20%) +2,4-D (5 mg l(-1))+Gln (100 mg l(-1))+sucrose (3%) and were used to detoxify a paint preservative Troysan S 89 (a mixture of carbendazim, diuron and ochthilinone). FTIR and UV spectral analytical studies revealed the phytotransformation of Troysan S 89 by Blumea cell suspension cultures. The non-toxic nature of the products formed after phytotransformation was confirmed by phytotoxicity, cytogenotoxicity while non-carcinogenic nature by Ames tests. The novelty of the present study is effective communal degradation of a mixture of three toxicants in Troysan S 89 by cell suspension cultures of Blumea. This work suggested that Blumea cell suspensions might be able to contribute to the wider and safer application of phytoremediation. 相似文献
49.
Yew SY Shekhawat G Wangoo N Mhaisalkar S Suri CR Dravid VP Lam YM 《Nanotechnology》2011,22(21):215606
Self-assembly of peptides provides the possibility of achieving relatively long range order on surfaces. These ordered peptides can also form channels that can be used as conduction channels. In the past, studies were focused on electron conduction through the secondary structure and amine bond of peptides and these restrict conduction of electrons over a short range (a few nanometers). In this work, we demonstrate the realization of electron conduction over a longer range of a few hundred nanometers via π-π stacking of the phenyl groups in the tyrosine residue of a single peptide. The peptide used in this work was designed with a phenyl ring for π-π stacking at one end and a carboxylic group at the other end for binding to aminopropyltriethoxysilane (APTES) treated silicon wafer. The distance between the peptides is controlled by a disulfide bond formed between neighboring cysteine residue and also by the amine groups of aminopropyltriethoxysilane. We demonstrate that the self-assembled peptide is conducting in the dry state over hundreds of nanometers, realizing the possibility of using peptide as a molecular wire. 相似文献
50.
Specific heats were measured on two samples of HoBa2Cu3O7−δ
in the temperature range 1·7 K to 10 K. In addition to the known Schottky behaviour, a peak in the specific heat curve was
observed near 7·9 K in both the samples. This peak is probably due to impurity contribution and the specific heat measurements
were undertaken in holmium oxide (Ho2O3), which was the suspected impurity. However, no peak was observed in the specific heat curve of holmium oxide 相似文献