共查询到20条相似文献,搜索用时 843 毫秒
1.
Alexander Bauer Christian Leonhartsberger Peter Bösch Barbara Amon Anton Friedl Thomas Amon 《Clean Technologies and Environmental Policy》2010,12(2):153-161
Currently an increasing demand for renewable energy can be observed. A part of this demand could be covered by the production
of energy from agrarian biomass. Due to the limited availability of arable land, food and feed production are starting to
compete for agrarian resources. A way out of this dilemma is to develop concepts that are based on otherwise unused agrarian
biomass like straw and include new technologies for the fermentation of lignocellulosic biomass. In this paper, the energy
potentials of two different cropping systems are compared. In the energy-based crop rotation system all crops were used either
for biogas or ethanol production. In the biorefinery-based approach, the various crops were used in cascades for the production
of food as well as feed. Experimental laboratory work and field trials were combined to calculate energy and biomass yields
of the crops under investigation. The results demonstrate that steam explosion pretreatment of wheat straw led to a 30% increase
in the specific methane yield. The calculated energy output of the biorefinery-based crop rotation system amounted to a total
of 126 GJ ha−1 year−1. Extrapolating this energy output to the total arable land of the EU-27 member states, 13,608 PJ of energy could be produced.
Therefore, biorefinery-based crop rotation systems could provide approximately three times more energy to the European population
than energy-based crop rotation systems. 相似文献
2.
Lee Tin Sin W. A. W. A. Rahman A. R. Rahmat N. A. Morad M. S. N. Salleh 《International Journal of Thermophysics》2010,31(3):525-534
The specific heat capacity (C
sp) of polyvinyl alcohol (PVOH) blends with cassava starch (CSS) was studied by the differential scanning calorimetry method. Specimens of PVOH–CSS blends: PPV37 (70 mass% CSS)
and PPV46 (60 mass% CSS) were prepared by a melt blending method with glycerol added as a plasticizer. The results showed
that the specific heat capacity of PPV37 and PPV46 at temperatures from 330 K to 530 K increased from (2.963 to 14.995) J·
g−1 · K−1 and (2.517 to 14.727) J · g−1· K−1, respectively. The specific heat capacity of PVOH–CSS depends on the amount of starch. The specific heat capacity of the
specimens can be approximated by polynomial equations with a curve fitting regression > 0.992. For instance, the specific
heat capacity (in J · g−1 · K−1) of PPV37 can be expressed by C
sp = −17.824 + 0.063T and PPV46 by C
sp = −18.047 + 0.061T, where T is the temperature (in K). 相似文献
3.
Jinsheng Liao Bao Qiu He-Rui Wen Yong Li Ruijin Hong Hangying You 《Journal of Materials Science》2011,46(5):1184-1189
Monodispersed spheres (1–4 μm in diameter) of BaWO4:Eu3+ (hereafter BWO:Eu) red-phosphor exhibiting intense emission at 615 nm were synthesized via a mild hydrothermal method. X-ray
diffraction, scanning electron microscope, photoluminescence excitation and emission spectra, and decay curve were used to
characterize the properties of BWO:Eu phosphors. An intense red emission was obtained by exciting either into the 5L6 state with 394 nm or the 5D2 state with 465 nm, that correspond to two popular emission lines from near-UV and blue LED chips, respectively. The values
of Ω
2,4 experimental intensity parameters (13.8 × 10−20 and 8.2 × 10−20 cm2) are determined. The high-emission quantum efficiency of the BWO:Eu phosphor suggests this material could be promising red
phosphors for generating white light in phosphor-converted white light-emitting diodes. 相似文献
4.
Guo Zhou Shibing Ni Xiaolei Sun Xinghui Wang Qi Wang Deyan He 《Journal of Materials Science: Materials in Electronics》2011,22(2):174-178
Sn1−x
Ni
x
O2 nanostructures such as nanocubes, nanospheres and hollow spheres were synthesized by a simple hydrothermal method. Room temperature
photoluminescence spectra of the as-synthesized samples display a strong yellow emission at about 600 nm and a weak blue emission
at about 430 nm. The as-prepared and annealed Sn1−x
Ni
x
O2 (x = 0, 0.01, 0.02, 0.04) were characterized by X-ray diffraction, field emission scanning electron microscopy, Raman spectrum,
UV–Vis absorption spectra, and room temperature photoluminescence spectra. By investigating the relationship between the Raman
band centered at 560 cm−1 and the photoluminescence of the samples, we suggest that the broad yellow emission and weak blue emission primarily originate
from singly ionized oxygen vacancies and tin interstitials, respectively. 相似文献
5.
H. M. A. Soliman A. B. Kashyout Mohamed S. El Nouby A. M. Abosehly 《Journal of Materials Science: Materials in Electronics》2010,21(12):1313-1321
Nanoscaled tungsten oxide thin films were fabricated by galvanostatic electrodeposition. The effect of preparation parameters
such as tungsten ions concentration, pH, current density and annealing on the properties and performance of WO3 thin films electrochromic materials was investigated. XRD, SEM–EDS, TEM, FTIR, UV–VIS spectrophotometry, and electrochemical
measurements were utilized to characterize the structural and compositional properties as well as the electrochromic behaviour
of the prepared thin films. Triclinic WO3 structure was prepared at 0.1 M W+ and current density of 0.5 mA cm−2, while at 0.2 M W+ and 1 mA cm−2, orthorhombic structure was revealed. High energy gap of 3.5 eV with diffusion coefficient of 6.81 × 10−11 cm2 S−1 and coloration efficiency of 62.68 cm2 C−1 were obtained for the films prepared at pH 2, 1 mA cm−2, and 0.1 M W+. 相似文献
6.
Julia van Drunen Baodong Zhao Gregory Jerkiewicz 《Journal of Materials Science》2011,46(18):5931-5939
We investigate the influence of micro-sandblasting and electrochemical passivation on properties such as corrosion rate and
surface roughness, which are important to the biocompatibility of titanium (Ti), using surface analysis techniques and electrochemical
measurements. Results of microscopy and surface profilometry experiments reveal roughened but uniform surface topography with
an average surface roughness in the 0.87–1.06 μm range, depending on the alternating current passivation voltage applied to
the micro-sandblasted samples. Open circuit potential versus time measurements in Hank’s Balanced Salt Solution (HBSS, a simulated
body fluid) allow determination of the corrosion potential (E
corr) and reveal a shift of E
corr toward higher values upon passivation, thus pointing to increased corrosion stability. Corrosion rates in HBSS range between
0.049 and 0.288 μm year−1 for micro-sandblasted and passivated Ti, as compared to that for the micro-sandblasted and non-passivated surface that is
0.785 μm year−1. Results from this study demonstrate that micro-sandblasting coupled with electrochemical passivation provides a roughened
surface with increased corrosion stability and a low corrosion rate in HBSS. Application of this technique to Ti in medical
and dental applications may be expected to result in an improvement of biocompatibility. 相似文献
7.
Kousuke Shioi Naoto Hirosaki Rong-Jun Xie Takashi Takeda Yuan Qiang Li 《Journal of Materials Science》2010,45(12):3198-3203
Novel α-SiAlON:Eu2+-based yellow oxynitride phosphors with the formula Sr0.375−x
Eu
x
2+Si12−m−n
Al
m+n
O
n
N16−n
(m = 0.75, n = x = 0.004–0.04) have been prepared by firing the powder mixture of SrSi2, α-Si3N4, AlN, and Eu2O3 at 2,000 °C for 2 h under 1 MPa nitrogen atmosphere. The luminescence properties, the dependence of the activator concentration
of Eu2+ and the thermal stability of Sr-α-SiAlON:Eu2+ phosphor have been investigated in comparison with Ca-α-SiAlON:Eu2+ phosphor. Similar to Ca-α-SiAlON:Eu2+ phosphor, Sr-α-SiAlON:Eu2+ phosphor has the excitation wavelength ranging from the ultraviolet region to 500 nm, and exhibit intense yellow light. The
strongest luminescence was achieved at about x = 0.02 with the emission peak at 578 nm, slightly shorter than that of Ca-α-SiAlON:Eu2+ phosphor at 581 nm. Temperature-dependent emission intensity of Sr-α-SiAlON:Eu2+ phosphor is comparable to that of Ca-α-SiAlON:Eu2+ phosphor. The results suggest that the different position of the emission peak for Sr- and Ca-α-SiAlON:Eu2+ depends on the composition and the Stokes shift, and the thermal stability is nearly independent of Sr and Ca or fixed by
the network of (Si, Al)–(O, N) in α-SiAlON at the same Eu2+ concentration. 相似文献
8.
A series of copper/chromium hydrotalcite-like compounds (Cu/Cr-HTlcs) with Cu/Cr molar ratios from 1:1 to 4:1 synthesized
by coprecipitation reaction using NaOH and Na2CO3 as precipitation agents and their derived Cu/Cr mixed oxides (Cu/Cr-MO) were used in solid propellant for the first time.
The structure, morphology and thermal behaviors were investigated using inductively coupled plasma optical emission spectrometry,
X-ray diffraction, Fourier-transform infrared spectroscopy, N2 volumetric measurements, transmission electron microscope, thermogravimetry, and differential thermal analysis. The results
showed that a well crystallized Cu/Cr-HTlcs with CO3
2− as interlayer anions could be obtained with Cu and Cr molar ratio of 2:1, system pH value between 9 and 11, aging time longer
than 24 h; the sample has a specific surface area of 107.8 m2 g−1 and average pore diameter is 9 nm with pore volume of 0.34 cm3 g−1; N2 adsorption–desorption isotherm is type IVb with H2-type hysteresis loop; thermal stability of the sample is relatively lower and the sample tends to be curled when the aging
time is prolonged to 1 week at room temperature. Solid propellant with Cu/Cr-MO catalyst exhibit significantly higher burning
rate of 9.64 mm s−1 than those without catalyst (6.28 mm s−1)/with CuO · Cr2O3 catalyst (9.07 mm s−1). Press index also decreases from 0.339 to 0.299, and mechanical performance on elongation for Cu/Cr-MO catalyzed propellant
has a clear enhancement. 相似文献
9.
Ehab A. El-Danaf Abdulhakim A. AlMajid Mahmoud S. Soliman 《Journal of Materials Science》2008,43(18):6324-6330
High-temperature tensile deformation of 6082-T4 Al alloy was conducted in the range of 623–773 K at various strain rates in
the range of 5 × 10−5 to 2 × 10−2 s−1. Stress dependence of the strain rate revealed a stress exponent, n of 7 throughout the ranges of temperatures and strain rates tested. This stress exponent is higher than what is usually observed
in Al–Mg alloys under similar experimental conditions, which implies the presence of threshold stress. This behavior results
from dislocation interaction with second phase particles (Mg2Si). The experimental threshold stress values were calculated, based on the finding that creep rate is viscous glide controlled,
based on creep tests conducted on binary Al–1Mg at 673 K, that gave n a value of 3. The threshold stress (σ
o) values were seen to decrease exponentially with temperature. The apparent activation energy for 6082-T4 was calculated to
be about 245 kJ mol−1, which is higher than the activation energy for self-diffusion in Al (Q
d = 143 kJ mol−1) and for the diffusion of Mg in Al (115–130 kJ mol−1). By incorporating the threshold stress in the analysis, the true activation energy was calculated to be about 107 kJ mol−1. Analysis of strain rate dependence in terms of the effective stress (σ − σ
o) using normalized parameters, revealed a single type of deformation behavior. A plot of normalized strain rate () versus normalized effective stress (σ − σ
o)/G, on a double logarithmic scale, gave an n value of 3.
Ehab A. El-Danaf—on leave from the Department of Mechanical Design and Production, College of Engineering, Cairo University,
Egypt. 相似文献
10.
S. Mathew Amit D. Saran Santhi Ani Joseph Bishwajeet Singh Bhardwaj Deep Punj P. Radhakrishnan V. P. N. Nampoori C. P. G. Vallabhan Jayesh R. Bellare 《Journal of Materials Science: Materials in Electronics》2012,23(3):739-745
CdSe quantum dots prepared by micro emulsion technique shows quantum confinement effect and broad emission at 532 nm. These
quantum dots have about 4.35 nm size, and they exhibit good nonlinear effects which are measured using z-scan technique. The
samples have a reverse saturation in the nonlinear absorption as nonlinear optical absorption coefficient β is 2.545 × 10−10 W m−1 and nonlinear optical refraction coefficient n
2 is −1.77 × 10−10 esu. The third-order nonlinear optical susceptibility is found to be 4.646 × 10−11 esu and also the figure of merit is 2.01 × 10−12 esu m. The optical limiting threshold which is found to be 0.346 GW/cm2 makes it a good candidate for device fabrication. 相似文献
11.
P. R. Deshmukh S. N. Pusawale A. D. Jagadale C. D. Lokhande 《Journal of Materials Science》2012,47(3):1546-1553
The amorphous hydrous ruthenium oxide (RuO2·nH2O) thin films were deposited by a simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method. These
films were characterized for their structural, surface morphological, and compositional study by means of X-ray diffraction
(XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and energy dispersive X-ray analysis
(EDAX) techniques. The wettability test was carried out by measuring the water contact angle. The scanning electron microscopy
study showed small RuO2 particles are grouped together to form porous agglomerates. The FT-IR study confirmed the formation of hydrous ruthenium
oxide films. The hydrophilic nature of ruthenium oxide (RuO2·nH2O) thin films was observed from water contact angle measurement. The presence of Ru and O in the film was confirmed by EDAX
analysis. The supercapacitor behavior of these films studied in 0.5 M H2SO4 electrolyte showed maximum specific capacitance of 162 F g−1 at 10 mV s−1 scan rate. These films exhibit 80% cycling performance after 2,000 cycles. The charge–discharge studies carried at 1 mA cm−2 current density revealed the specific power of 3.5 KW kg−1 and specific energy of 29.7 W Kg−1 with 93% coulombic efficiency. 相似文献
12.
Seung Hyun Jee Jun Young Oh Ho Sang Ahn Dong-Joo Kim Howard C. WikleIII Soo Ho Kim Young Soo Yoon 《Journal of Materials Science》2010,45(7):1709-1714
Li–B–W–O thin film serving as a solid-state electrolyte layer for a solid-state thin film battery has been deposited on a
stainless steel (SUS)/Si substrate by thermal evaporation deposition at room temperature. By energy dispersive X-ray spectroscopy
and inductively coupled plasma-atomic emission spectrometer measurements, the as-grown thin film showed a stoichiometry of
Li2.99BW1.8O9. The as-grown Li–B–W–O solid-state electrolyte thin film possessed an amorphous structure as confirmed by X-ray diffraction.
Field emission scanning electron microscopy measurements of the film cross section showed a dense structure that did not have
any large defects such as cracks or voids. For a cell structure of SUS/Li–B–W–O/SUS/Si, an impedance measurement conducted
at room temperature revealed an ionic conductivity of 2.15 × 10−7 S cm−1 with activation energy of 0.52 eV, which suggests that Li–B–W–O thin film can possibly be used as an electrolyte in solid-state
thin film batteries. 相似文献
13.
The coarsening behavior of rod-shaped and spherical δ-Ni2Si precipitates in a Cu–1.86 wt% Ni–0.45 wt% Si alloy during aging at 823–948 K has been investigated by measuring both precipitate
size by transmission electron microscopy (TEM) and solute concentration in the Cu matrix by electrical resistivity. The rod-shaped
δ precipitates have an elongated shape along 〈[`5] 5 8 \overline{5} 5 8 〉m and a {110}m habit-plane facet. The coarsening theory of a spherical precipitate in a ternary alloy developed by Kuehmann and Voorhees
(KV) has been modified to a case of rod-shaped precipitates. The coarsening kinetics of average size of the rod-shaped and
spherical δ precipitates with aging time t obey the t
1/3 time law, as predicted by the modified KV theory. The kinetics of depletion of the supersaturation with t are coincident with the predicted t
−1/3 time law. Application of the modified KV theory has enabled calculation of the energies of sphere, {110}m and rod-end interfaces from the data on coarsening alone. The energy of the {110}m interface having a high degree of coherency to the Cu matrix is estimated to be 0.4 J m−2, the incoherent sphere-interface energy 0.6 J m−2, and the rod-end interface energy 5.2 J m−2. 相似文献
14.
Zhanxu Yang Zhilin Song Gang Chu Xiaoxue Kang Tieqiang Ren Wensheng Yang Qingdong Qiao 《Journal of Materials Science》2012,47(9):4205-4209
Layered LiCo1/3Ni1/3Mn1/3O2 has been modified with Co–Al-mixed metal oxide (CoAl-MMO). The surface-modified materials were characterized by X-ray diffraction,
field emission scanning electron microscopy, and galvanostatic charge–discharge cycling. The CoAl-MMO-coated LiCo1/3Ni1/3Mn1/3O2 had an initial discharge specific capacity of 178.1 mAh g−1 within the potential range of 2.75–4.5 V (vs. Li+/Li), and its discharge specific capacity is 175.0 mAh g−1 after 50 cycles, much higher than that of the pristine LiCo1/3Ni1/3Mn1/3O2 (148.4 mAh g−1). The improvement could be attributed to the CoAl-MMO coating layer that would hinder interaction between LiCo1/3Ni1/3Mn1/3O2 and electrolyte and stabilize the structure of LiCo1/3Ni1/3Mn1/3O2. Moreover, DSC showed that the CoAl-MMO-coated LiCo1/3Ni1/3Mn1/3O2 had a higher thermal stability than the pristine LiCo1/3Ni1/3Mn1/3O2. Therefore, the CoAl-MMO-coated LiCo1/3Ni1/3Mn1/3O2 could be a high-performance cathode material for lithium-ion batteries. 相似文献
15.
The present investigation describes the synthesis of uniform sponge-like Ni(OH)2 nanoparticles on stainless steel substrates by a two-step successive ionic layer adsorption and reaction method; the study
also explores electrochemical properties. The formation of the β-phase Ni(OH)2 and it’s nanocrystallinity are confirmed by X-ray diffraction and X-ray photoelectron spectroscopy studies. Scanning electron
microscopy revealed the formation and random distributions of porous and sponge-like nanoparticles with high Brunauer–Emmett–Teller
surface area of 56.4 m2 g−1. The maximum specific capacitance of 428 F g−1 was obtained at 5 mV s−1 in a 2 M KOH electrolyte, indicating promising supercapacitor applications with remarkable rate capability. These results
suggest the importance of rational design and synthesis of thin nanomaterials for high-performance energy applications. 相似文献
16.
Yong Du Kefeng F. Cai Shirley Z. Shen Baijun An Zhen Qin Philip S. Casey 《Journal of Materials Science: Materials in Electronics》2012,23(4):870-876
Bi2Te3/Polythiophene (PTH) thermoelectric bulk composite materials were prepared by a two-step method. Firstly, Bi2Te3 and PTH nanopowders were prepared by hydrothermal synthesis and chemical oxidative polymerization, respectively. Secondly,
the mixture of the Bi2Te3 and PTH nanopowders (50:50 wt) was pressed under vacuum at 80 MPa and 298, 473, or 623 K. For comparison, Bi2Te3 powders were hot pressed at 623 K. The bulk materials were analyzed by conventional methods, such as X-ray diffraction (XRD),
Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA) and field emission scanning electron microscopy
equipped with electron dispersive X-ray spectroscopy. The XRD and TGA results showed that the PTH decomposed when the hot
pressing temperature exceeded 473 K, and Bi2Te2S phase was formed. The thermoelectric properties of the bulk composite materials were investigated. The composite pressed
at 623 K showed a higher power factor, ~2.54 μ Wm−1 K−2 at 473 K, which is as ~20 times as that of the composite pressed at 473 K, although, it is still much lower than that of
the pressed Bi2Te3 material (~1,266 μ Wm−1 K−2 at 348 K). 相似文献
17.
Fernanda M. Nodari Rodolfo L. Patyk Lucimara S. Roman Adriano R. V. Benvenho Ivo A. Hümmelgen Eduardo K. C. Yoshikawa Jonas Gruber 《Journal of Materials Science: Materials in Electronics》2010,21(12):1235-1239
We describe the optical and electrical characterization of a poly(p-phenylenevinylene) derivative: poly(2-dodecanoylsulfanyl-p-phenylenevinylene) (12COS-PPV). The electrical characterization was carried out on devices with the FTO\PEDOT:PSS\12COS-PPV/Al
structure. Positive charge carrier mobility μ
h
of ~1.0 × 10−6 cm2 V−1 s−1 and barrier height φ of ~0.1 eV for positive charge carrier injection at the PEDOT:PSS/12COS-PPV interface were obtained
using a thermionic injection model. FTO\PEDOT:PSS\12COS-PPV/Ca devices exhibited green-yellow electroluminescence with maximum
emission at λ = 540 nm. 相似文献
18.
Francisco Ramos-Brito Manuel García-Hipólito Castulo A. Alejo-Armenta Enrique Camarillo José M. Hernández Héctor O. Murrieta Ciro Falcony 《Journal of Materials Science》2008,43(13):4527-4533
Polycrystalline micro-spheres of undoped (ZO) and praseodymium-doped zirconia (PrZO) were obtained for different reactor temperatures
(T
r) by the ultrasonic assisted chemical vapor synthesis process. SEM micrographs for T
r ≥ 400 °C show that (a) the materials were synthesized in a powder form in the presence of particles spherical in shape with
an average size of 3 μm and a narrow size distribution, and (b) the production of spherical particles had a remarkable increase
on rate production and no considerable changes on their average size as T
r rises. EDS studies show an atomic percent composition of O-67.5, Zr-30.0, Pr-0.3, and Cl-2.2 for PrZO micro-spheres obtained
at 500 °C, which is in good agreement with zirconium oxide stoichiometry. XRD patterns of ZO and PrZO micro-spheres for T
r ≥ 400 °C show a polycrystalline tetragonal I structure with crystallite size values remaining below 20 nm. The photoluminescence
emission spectrum of PrZO micro-spheres shows peaks overlapping the intrinsic emission of zirconia, attributed to inter-level
transitions in Pr3+ ions: 490 and 505 nm: 3P0 − 3H4, 565 nm: 3P1 + 1I6 − 3H5, 615 nm: 1D2 − 3H4 and 645 nm: 3P0 − 3H6. The excitation spectrum for the main emission peak (615 nm) shows that Pr3+ ions in PrZO show a preferred excitation through its 4f5d absorption band. 相似文献
19.
Jingqi Zhang Hongshuang Di Hongtao Wang Kun Mao Tianjun Ma Yu Cao 《Journal of Materials Science》2012,47(9):4000-4011
The hot deformation behavior of Ti-15-3 titanium alloy was investigated by hot compression tests conducted in the temperature
range 850–1150 °C and strain rate range 0.001–10 s−1. Using the flow stress data corrected for deformation heating, the activation energy map, processing maps and Zener–Hollomon
parameter map were developed to determine the optimum hot-working parameters and to investigate the effects of strain rate
and temperature on microstructural evolution of this material. The results show that the safe region for hot deformation occurs
in the strain rate range 0.001–0.1 s−1 over the entire temperature range investigated. In this region, the activation energy is ~240 ± 5 kJ/mol and the ln Z values vary in range of 13.9–21 s−1. Stable flow is associated with dynamic recovery and dynamic recrystallization. Also, flow instabilities are observed in
the form of localized slip bands and flow localization at strain rates higher than 0.1 s−1 over a wide temperature range. The corresponding ln Z values are larger than 21 s−1. The hot deformation characteristic of Ti-15-3 alloy predicted from the processing maps, activation energy map, and Zener–Hollomon
parameter map agrees well with the results of microstructural observations. 相似文献
20.
Li2FeSiO4/C composites were one-step synthesized under hydrothermal conditions at 200 °C for 72 h using glucose as carbon source. By
adjusting the quantity of added glucose, we obtained varied Li2FeSiO4/C composites with different size and morphology. A series of electrochemical tests demonstrate that the Li2FeSiO4/C nanoparticles with diameters about 20 nm have higher discharge capacity, and slower capacity fading in comparison with
Li2FeSiO4 and other Li2FeSiO4/C composites. Li2FeSiO4/C nanoparticles deliver a discharge capacity of 136 mAh g−1 at 0.2 C, and after 100 cycles, the discharge capacity remains 96.1%. Furthermore, Li2FeSiO4/C nanoparticles also exhibit an excellent rate capability with a capacity of about 80 mAh g−1 at 10 C. 相似文献