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1.
Xinshen Du Yinping Li Xing Liu Xiong Wang Celine Huselstein Yanteng Zhao Peter R. Chang Yun Chen 《Journal of materials science. Materials in medicine》2014,25(3):823-833
Polyurethane prepolymer (PUP) was first synthesized from polycaprolactone diol and isophorone diisocyanate; and then a series of zein-based polyurethane (ZEPU) sheets was fabricated from PUP and zein (ZE) using a hot press and moulding process without addition of other additives. Effects of ZE content (WZE) on the structure and properties of the resultant ZEPU sheets were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, dynamic mechanical analysis, tensile testing, and dissolubility testing in alcohol. The results indicated that cross-linking and grafting reactions occurred between ZE and PUP to form new polyurethane showing a higher thermal stability, flexibility, and alcohol-resistance than the neat ZE sheets. For example, the elongation at break of ZEPU with 50 % WZE was 211.2 %, which was 47 times higher than that of neat ZE sheet. ZE molecules acted as both cross-linkers and polymer fillers in ZEPU sheets. The cytotoxicity and cytocompatibility of ZEPU sheets were evaluated by cell culture in vitro. The ZEPU sheets showed non- or low-cytotoxicity, and L929 cells grew and expanded well on the surfaces of the sheets with WZE over 50 %. Undoubtedly, the fabrication of ZE-based polyurethanes without toxic additives such as catalysts, cross-linkers and chain extenders improved the physical properties and cytocompatibility of zein, thus widening the possible range of applications for zein-based biomaterials. 相似文献
2.
Hua Wang Jian Li Jiwen Xu Ling Yang Minfang Ren 《Journal of Materials Science: Materials in Electronics》2011,22(6):654-658
1–1 intergrowth-superlattice-structured Bi3TiNbO9–Bi4Ti3O12 (BTN–BIT) ferroelectric thin films have been prepared on p-Si substrates by sol-gel processing. The precursor films are crystallized
in the desired intergrown BTN–BIT superlattice structures by optimizing the processing conditions. Synthesized BTN–BIT thin
films annealed below 750 °C are polycrystalline, uniform and crack-free, no pyrochlore phase or other second phase, and exhibited
good ferroelectric properties. As the annealing temperature increases from 600 to 700 °C, both remanent polarization P
r and coercive electric field E
c of BTN–BIT thin films increase, but the pyrochlore phase in BTN–BIT films annealed above 750 °C will impair the ferroelectric
properties. The BTN–BIT thin films annealed at 700 °C have a P
r value ~19.1μC/cm2 and an E
c value ~135 kV/cm. 相似文献
3.
K. Nakamura J. Aoki K. Morishita M. Yamamoto 《Clean Technologies and Environmental Policy》2000,2(3):174-178
The volatilization of mercuric chloride (HgCl2) and methyl mercuric chloride (CH3HgCl) by the 45 strains (35 Pseudoalteromonas sp., 2 Vibrio sp., 1 Aeromonas sp., and 7 unclassified) of the most mercury-resistant bacteria from Minamata Bay seawater was examined in various physiological
conditions. The bacteria could grow and volatilize HgCl2 in the liquid medium containing 1–10% NaCl. Two Pseudoalteromonas strains could grow and volatilize HgCl2 at pH levels ranging from 5.0 to 10.0. The resting cells of 43 strains could volatilize HgCl2 at concentrations ranging from 30 to 68% after 1-h incubation at 30 °C. The resting cells of 41 strains could volatilize
CH3HgCl at concentrations ranging from 13 to 88% after 1-h incubation at 30 °C. Ninety-two percent of mercury was removed from
the phosphate buffer containing 0.1 μg/ml by a resting cell of Pseudoalteromonas strain H-4 after 30-min incubation at 30 °C. We were able to screen the special bacteria, which could volatilize mercury
compounds at a high rate in various physiological conditions, for the purpose of developing mercury removal methods using
bacteria.
Received: 26 April 2000 / Accepted: 16 June 2000 相似文献
4.
C. Godet L. Schmirgeld L. Zuppiroli G. Sardin S. Gujrathi K. Oxorn 《Journal of Materials Science》1991,26(23):6408-6418
Hydrogenated boron thin films have been deposited at temperatures in the range 50–100 °C with the radiofrequency plasma decomposition
of diborane B2H6 diluted in hydrogen. The chemical composition of the films has been determined by elastic recoil detection and by the Castaing
microprobe techniques. We have found that the as-deposited films contain 10–20 at % H and that they react with the ambient
atmosphere within a few days and reach a final composition close to B0.64H0.12O0.12C0.06N0.06. The optical properties of the as-deposited films studied by spectroscopic phase-modulated ellipsometry in the range 1.7–5.0
eV are characteristic of the high optical gap semiconductors. The electron diffraction measurements performed onin situ annealed samples show that the films are amorphous up to 950 °C. Infrared spectroscopy investigations performed on the as-deposited
films have revealed two hydrogen bonding sites: B-H terminal bonds and B-H-B bridge bonds, along with some B-O-B groups. Upon
exposure to the atmosphere, the vanishing of B-H-B and B-O-B bridge bonds and the increase of B-H and B-O-H absorption bands
after 1 day, are observed.
On leave from Physics Department, CNEA, Avenida Libertador 8250, 1429 Buenos-Aires, Argentina, and CONICET. 相似文献
5.
Ju-Yeon Lee Jin-Hyang Kim Won-Taek Jung Young Kum Park 《Journal of Materials Science》2007,42(11):3936-3943
2,3-Di-(2′-hydroxyethoxy)benzylidenemalononitrile (3) was prepared and condensed with 2,4-toluenediisocyanate and 3,3′-dimethoxy-4,4′-biphenylenediisocyanate to yield novel Y-type
polyurethanes 4–5 containing 2,3-dioxy benzylidenemalononitrile group as a nonlinear optical (NLO)-chromophore, which constituted parts of
the polymer backbones. Polyurethanes 4–5 were soluble in common organic solvents such as acetone and N,N-dimethylformamide. They showed a thermal stability up to 270 °C in thermogravimetric analysis thermograms and the glass-transition
temperatures (T
g) obtained from differential scanning calorimetry thermograms were around 116–135 °C. The second harmonic generation (SHG)
coefficients (d
33) of poled polymer films at 106.4 mm−1 fundamental wavelength were around 9.07 × 10−19 C (2.72 × 10−9 esu). The dipole alignment exhibited high thermal stability up to 10 °C higher than T
g, and there was no SHG decay below 145 °C due to the partial main-chain character of the polymer structure, which was acceptable
for nonlinear optical device applications. 相似文献
6.
P. A. Shcheglov S. A. Men’shikh S. G. Prutchenko L. F. Rybakova Yu. Ya. Tomashpol’skii 《Inorganic Materials》2000,36(1):67-71
Single-crystal Pb5Ge3O11 films 5–105 μm thick, adhering well to platinum substrates, were prepared by pyrolysis of metalorganic precursors in combination
with in situ sol-gel processing. The best films consisted of densely packed crystallites ranging in size from 200 to 300 μm,
with hexagonal habits. A welldefined ferroelectric transition was revealed at 170–180°C. The typical parameters of the films
are ɛ20 = 30–40, tan δ ≃0.02, ɛmax ≃200, Ps = 3.2 μC/cm2,E
c
= 16 kV/cm, and ρ = 108-109 Ω cm, in agreement (except for ɛmax) with those of lead germanate crystals 相似文献
7.
Pulsed electrodynamic breakage of thin (∼20-nm-thick) aluminum films deposited onto polymer substrates have been experimentally
studied. The character of film fracture depends on the level of supplied electric energy W. For 3.5 kJ/g < W < 4.3 kJ/g, discontinuities (striations) are formed in the transverse direction relative to the applied electric field. At
high current densities on a level of ∼(1–3) × 1012 A/m2 and explosion times within 50–300 ns, the integral of action to explosion varies within (0.79–1.08) × 1017 A s/m2 depending on the rate of energy supply and differs from published data for relatively massive conductors. 相似文献
8.
I. G. Gogidze P. B. Kuminov A. V. Sergeev E. M. Gershenzon 《Technical Physics Letters》1999,25(1):47-49
It is shown that an inductive high-speed nonequilibrium detector for electromagnetic radiation can be fabricated using thin
YBaCuO films. An electronic detection regime has been obtained for the first time using a low-temperature inductive YBaCuO
detector in the measuring frequency band Δf=1–50 MHz and it has been shown that no bolometric detection regime exists at operating temperatures far below the superconducting
transition. The time constant of the low-temperature inductive YBaCuO detector in the electronic regime is determined only
by the electron-phonon interaction time in the nodal regions τ
e-ph
d
. The detector has the following limiting characteristics: when the operating temperature is reduced from 10 to 1K, the time
constant τ
D
varies between 10 and 100 ps and the sensitivity D* improves substantially from 109 to 4×1012 W−1 cm Hz1/2.
Pis’ma Zh. Tekh. Fiz. 25, 14–19 (January 26, 1999) 相似文献
9.
Felicia S. Manciu Young Yun William G. Durrer James Howard Ute Schmidt Chintalapalle V. Ramana 《Journal of Materials Science》2012,47(18):6593-6600
We present a comparative microscopic and spectroscopic study of the morphology and composition of WO3 and W0.95Ti0.05O3 thin films, grown by radio-frequency magnetron reactive sputtering at substrate temperatures varied from room temperature to 500 °C, using atomic force microscopy (AFM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). With increasing growth temperature, the AFM results show increase in the average crystallite size and in the surface roughness for both undoped and doped samples. The AFM data, along with the Raman results, clearly indicate that for the given set of experimental conditions, higher growth temperatures are required to obtain crystalline Ti-doped WO3 films than for WO3 films. Also, the Raman results suggest a potential phase transformation from a monoclinic WO3 structure to an orthorhombic, but more probably a tetragonal, configuration in the W0.95Ti0.05O3 thin films. This remark is based on the observed shifting, with Ti doping, to lower frequencies of the Raman peaks corresponding to W–O–W stretching modes of WO3 at 806 and 711 cm−1 to 793 and 690 cm−1, respectively. XPS data indicate that the doped material has a reduced WO3−x stoichiometry at the surface, with the presence of W6+ and W5+ oxidation states; this observation could also be related to the existence of a different structural phase of this material, corroborating with the Raman measurements. 相似文献
10.
CuIn3S5 compound was prepared by direct reaction of high-purity elemental copper, indium and sulphur. CuIn3S5 thin films were prepared from powder by thermal evaporation under vacuum (10−6 mbar) onto glass substrates. The glass substrates were heated from 30 to 200 °C. The powder was characterized for their structural
and compositional properties by using X-ray diffraction (XRD) and energy dispersive X-ray (EDAX). The XRD studies revealed
that the powder exhibiting P-chalcopyrite structure. From the XRD data, we calculated the lattice parameters a and c. Then, the cation–anion bond lengths l
AC and l
BC are deduced. The films were characterized for their structural, compositional, morphological and optical properties by using
XRD, EDAX, atomic force microscopy and optical measurement techniques (transmittance and reflectance). XRD analysis revealed
that the films deposited at a room temperature (30 °C) are amorphous in nature, whereas those deposited on heated substrates
(≥75 °C) were polycrystalline with a preferred orientation along (112) of the chalcopyrite phase. The surface morphological
analysis revealed that the films grown at different substrate temperature had an average roughness between 1.1 and 4.8 nm.
From the analysis of the transmission and reflection data, the values of direct and indirect band gap of the films were determined.
We found that the optical band gap decreases when the substrate temperature increases. 相似文献
11.
In this study, we have studied the effect of repeated annealing temperatures on TiO2 thin films prepared by dip-coating sol–gel method onto the glasses and silicon substrates. The TiO2 thin films coated samples were repeatedly annealed in the air at temperatures 100, 200, and 300 °C for 5 min period. The
dipping processes were repeated 5 to 10 times in order to increase the thickness of the films and then the TiO2 thin films were annealed at a fixed temperature of 500 °C for 1 h period. The effect of repeated annealing temperature on
the TiO2 thin films prepared on glass substrate were investigated by means of UV–VIS spectroscopy, X-ray diffraction (XRD), and atomic force microscopy (AFM). It was observed that the thickness, average crystallite size, and average grain size of TiO2 samples decreased with increasing pre-heating temperature. On the other hand, thickness, average crystallite size, and average
grain size of TiO2 films were increased with increasing number of the layer. Al/TiO2/p-Si metal–insulator–semiconductor (MIS) structures were obtained from the films prepared on p-type single silicon wafer
substrate. Capacitance–voltage (C–V) and conductance–voltage (G/ω–V) measurements of the prepared MIS structures were conducted at room temperature. Series resistance (R
s) and oxide capacitance (C
ox) of each structures were determined by means of the C–V curves. 相似文献
12.
Highly photosensitive films of CdS have been prepared using the thick film technique. The films obtained from the composition
containing CdS-100, CdCl2−10 and CuCl2−0·05 parts by weight (reacted at 500° C) are found to give the best photosensitivity on firing at 600° C. The ratio of light
to dark current ∼108–109 which is considerably higher than what is reported for thin films, single crystals and sintered layers. A strong chemisorption
of oxygen is found to be responsible for high photosensitivity. The spectral response for doped CdS film is similar to that
obtained for thin films, single crystals and sintered layers and also shows a red shift with increasing Cu concentration.
However, the undoped CdS has a broad spectral response at room temperature ranging fromλ=550 to 690 nm; unlike the thin films and single crystals which give a sharp peak atλ=510 to 520 nm. A probable explanation has been suggested for this type of behaviour.
NCL Communication No. 2502. 相似文献
13.
When titanium/silicon-dioxide (Ti/SiO2) structures prepared by depositing titanium (Ti) on thermally oxidized silicon in vacuum were heated to temperatures of 800–1000°C
in flowing oxygen gas, silicon surfaces were covered with a mixture films containing preferentially (110)-oriented Ti02 instead of the SiO2 films. The thickness of the mixture films could be determined by that of the deposited Ti films. Titanium silicide grew only
in the region near between the grown mixture film and the silicon substrate. The dielectric constants of the grown mixture
films increased exponentially with increasing oxidation temperature and increased slowly with increasing the Ti film thickness,
while the breakdown field strength increased slowly with increasing oxidation temperature and increased exponentially with
increasing the Ti film thickness. The oxide films prepared at 1000°C had dielectric constants of (15–25)ɛo resistivities of 1010–1011 Ω cm, and breakdown field strengths of about 106 V/cm.
Received: 10 February 1998 / Accepted: 10 March 1998 相似文献
14.
Y. Kumashiro K. Nakamura T. Enomoto M. Tanaka 《Journal of Materials Science: Materials in Electronics》2011,22(8):966-973
The chemical vapor deposited (CVD) BP films on Si(100) (190 nm)/SiO
x
(370 nm)/Si(100) (625 μm) (SOI) and sapphire (R-plane) (600 μm) substrates were prepared by the thermal decomposition of
the B2H6–PH3–H2 system in the temperature range of 800–1050 °C for the deposition time of 1.5 h. The BP films were epitaxially grown on the
SOI substrate, but a two-step growth method, i.e., a buffer layer at lower temperature and sequent CVD process at 1000 °C
for 1.5 h was effective for obtaining a smooth film on the sapphire substrate. The electrical conduction types and electrical
properties of these films depended on the growth temperature, gases flow rates and substrates. The thermal conductivity of
the film could be replaced by the substrate, so that the calculated thermoelectric figure-of-merit (Z) for the BP films on the SOI substrate was 10−4–10−3/K at 700–1000 K. Those on the sapphire substrate were 10−6–10−5/K for the direct growth and 10−5–10−4/K for the two-step growth at 700–900 K, indicating that the film on a sapphire by two-step growth would reduce the defect
concentrations and promote the electrical conductivity. 相似文献
15.
Two series of WO
x
/ZrO2 samples are prepared by equilibrium adsorption from H2O2 solutions at pH 1.8 containing two different precursor anions, [W2O3(O2)4(H2O)2]2− and [H2W12O40]6−. The starting material is amorphous zirconium oxyhydroxide. The maximum W densities obtained are larger than that reported
in the literature for systems synthesized by the same method using aqueous non-peroxide solutions. In the case of the metatungstate
precursor, this increase is attributed to the generation of additional anchoring sites by interaction between the amorphous
support and H2O2. The high uptake achieved when the peroxo complex is used as a precursor is a result of both the ZrO
x
(OH)4-2x
–H2O2 interaction and low nuclearity of the adsorbing anion. The materials are characterized by XRD, DR–UV–vis, Micro-Raman and
FT-IR spectroscopy. The surface acidities of samples with identical W loading prepared by equilibrium adsorption from the
[H2W12O40]6−–H2O2 system and by impregnation with aqueous solution of ammonium metatungstate are investigated by FT-IR spectroscopy of CO adsorbed
at 80 K. 相似文献
16.
The voltage ΔV and electric current ΔI of the p- and n-type Cu/Bi–Te/Cu composite thermoelectric devices were measured as a function of ΔT for four regions of the intrinsic Bi–Te compound, Cu/Bi–Te and Bi–Te/Cu interfaces and Cu/Bi–Te/Cu composite using thermocouples
set at intervals of s = 2 and 6 mm, where the lengths of Bi–Te compound and copper are 4 and 5 mm, respectively. ΔV and ΔI of all regions tended to increase linearly with an increase of ΔT. The resultant α was obtained from the relation ΔV/ΔT. The resultant α values of regions including the interface are much higher in absolute value than those of the intrinsic
Bi–Te compounds, so that the barrier thermo-emf is found to occur in the forward-bias direction. It indicates that the barrier
thermo-emf appears even in the semiconductor-metal junction, as in the case of the p–n junctions. The resultant α of Cu(T
H)/Bi–Te interface rich in the heat flow increases with an increase of ΔT, while that of Bi–Te/Cu(T
C
) interface poor in the heat flow decreases with an increase of ΔT. The ΔT-dependence of α of the interfaces is entirely opposite at the hot and cold sides. As a result, the resultant α of the p-
and n-type Cu/Bi–Te/Cu composites remained little varied with changes of ΔT, so that the present composites have a thermal stability superior to the intrinsic Bi–Te compounds.The generating powers
ΔW
Bi-Te and ΔW
Cu/Bi-Te/Cu for the p- and n-type intrinsic Bi–Te compounds and Cu/Bi–Te/Cu composites increased parabolalically with an increase of
ΔT, and the ratios of ΔW
Cu/Bi–Te/Cu to ΔW
Bi–Te reached great values of 1.41 and 1.45 for the p- and n-type composites, respectively. It was thus found that the enhancement
in the resultant α of the composite materials results in a significant improvement in the conversion efficiency for generators. 相似文献
17.
Transparent and conducting SnO2 films are prepared at 500°C on quartz substrates by chemical vapour deposition technique, involving oxidation of SnCl2. The effect of oxygen gas flow rate on the properties of SnO2 films is reported. Oxygen with a flow rate from 0·8–1·35 lmin−1 was used as both carrier and oxidizing gas. Electrical and optical properties are studied for 150 nm thick films. The films
obtained have a resistivity between 1·72 × 10−3 and 4·95 × 10−3 ohm cm and the average transmission in the visible region ranges 86–90%. The performance of these films was checked and the
maximum figure of merit value of 2·03 × 10−3 ohm−1 was obtained with the films deposited at the flow rate of 1·16 lmin−1. 相似文献
18.
SA-KYUN RHA WON-JUN LEE SEUNG-YUN LEE DONG-WON KIM CHONG-OOK PARK 《Journal of Materials Science: Materials in Electronics》1997,8(4):217-221
Copper films having thickness 600 nm were prepared on TiN using chemical vapour deposition (CVD). The deposited films were
annealed at various temperatures (350–550°C) in Ar and H2(10%)-Ar ambients. The changes in the grain size of the films upon annealing were investigated. Annealing in an H2(10%)-Ar ambient produced normal grain growth; annealing in an Ar ambient caused grain growth to stop at 550°C. The grain
size followed a monomodal distribution and the mean size increased in proportion to the square root of the annealing time,
indicating the curvature of the grain is the main driving force for grain growth. Upon annealing at 450°C for 30 min in an
H2(10%)-Ar ambient, the average grain size of the film increased from 122 nm to 219 nm, and the resistivity decreased from 2.35
μΩ cm to 2.12 μΩ cm at a film thickness of 600 nm.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
Transparent conducting tin oxide thin films have been prepared by electron beam evaporation and spray pyrolysis methods. Structural,
optical and electrical properties were studied under different preparation conditions like substrate temperature, solution
flow rate and rate of deposition. Resistivity of undoped evaporated films varied from 2.65 × 10−2 ω-cm to 3.57 × 10−3 ω-cm in the temperature range 150–200°C. For undoped spray pyrolyzed films, the resistivity was observed to be in the range
1.2 × 10−1 to 1.69 × 10−2 ω-cm in the temperature range 250–370° C. Hall effect measurements indicated that the mobility as well as carrier concentration
of evaporated films were greater than that of spray deposited films. The lowest resistivity for antimony doped tin oxide film
was found to be 7.74 × 10−4 ω-cm, which was deposited at 350°C with 0.26 g of SbCl3 and 4 g of SnCl4 (SbCl3/SnCl4 = 0.065).
Evaporated films were found to be amorphous in the temperature range up to 200°C, whereas spray pyrolyzed films prepared at
substrate temperature of 300– 370°C were poly crystalline. The morphology of tin oxide films was studied using SEM. 相似文献
20.
This work presents an experimental methodology for the measurement of interfacial energy (γSP) and work of adhesion (W
ad) of a metal–ceramic interface. A thin Au film was dewetted on the basal surface of sapphire substrates to form submicron-sized
particles, which were analyzed using the Winterbottom method to determine the equilibrated particle–substrate solid–solid
interfacial energy. Electron microscopy showed that a large portion of the particles contained grain boundaries, while all
of the single crystalline particles had three distinct morphologies and orientations with the substrate. Two orientation relationships
were determined from transmission electron microscopy, for which the interfacial energy in air at 1000 °C was determined:
Au (111)–sapphire (0001): γSP = 2.15 ± 0.04 J/m2, W
ad = 0.49 ± 0.04 J/m2; Au (100)–sapphire (0001): 2.18 ± 0.06 J/m2, W
ad = 0.55 ± 0.07 J/m2. 相似文献