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1.
A novel two-wavelength mid-infrared laser-absorption diagnostic has been developed for simultaneous measurements of vapor-phase
fuel mole fraction and liquid fuel film thickness. The diagnostic was demonstrated for time-resolved measurements of n-dodecane liquid films in the absence and presence of n-decane vapor at 25°C and 1 atm. Laser wavelengths were selected from FTIR measurements of the C–H stretching band of vapor
n-decane and liquid n-dodecane near 3.4 μm (3000 cm−1). n-Dodecane film thicknesses <20 μm were accurately measured in the absence of vapor, and simultaneous measurements of n-dodecane liquid film thickness and n-decane vapor mole fraction (300 ppm) were measured with <10% uncertainty for film thicknesses <10 μm. A potential application
of the measurement technique is to provide accurate values of vapor mole fraction in combustion environments where strong
absorption by liquid fuel or oil films on windows make conventional direct absorption measurements of the gas problematic. 相似文献
2.
F. N. Gygax P. Birrer B. Hitti E. Lippelt A. Schenck M. Weber 《Hyperfine Interactions》1991,64(1-4):489-495
μ
+ SR measurements have been performed in a single crystal indium sample between 12 K and 300 K with a stroboscopic μSR spectrometer.
The muonic Knight shiftK
μ and the muonic depolarization rate σ were obtained for various angles θ between the tetragonal crystallinec-axis and the direction of the external field. The isotropic part ofK
μ is only weakly temperature dependent and is consistent with the estimated Pauli spin susceptibility value. At a temperature
of 12 K the angular dependence ofM
2 (the second moment of the field distribution at the muon, obtained from the measured σ(θ) values) allows a clear determination
of the muon location — the symmetric tetrahedral site. The observed anisotropicK
μ cannot be explained by the dipoles at the In atoms responsible for the bulk magnetic susceptibility but probably originates
from an anisotropic Pauli spin susceptibility. 相似文献
3.
A. F.R. Rodriguez J. G. Santos L. B. Silveira A. C. Oliveira P. C. Morais O. A.C. Nunes 《The European physical journal. Special topics》2008,153(1):543-546
Photoacoustic spectroscopy (PAS) was used to investigate
samples produced from Baru (Dipteryx alata Vog.), a typical fruit from the Brazilian
Cerrado, which is considered as a good source of nutrients. The
photoacoustic (PA) spectra of samples prepared from Baru seeds present three
different absorption bands in the wavelength range 0.3–1.0 μm, named
Band-C, Band-S, and Band-L. We found that PAS can be useful for monitoring
the strong absorption of visible light by Baru's seeds constituents mainly
in the shorter wavelength measured range. This study is important from both
agricultural and commercial point of view once it introduces PAS as a
potential characterization technique allowing better control of fruit and
seed selection, storage and transportation. 相似文献
4.
A novel three-wavelength mid-infrared laser-based absorption/extinction diagnostic has been developed for simultaneous measurement
of temperature and vapor-phase mole fraction in an evaporating hydrocarbon fuel aerosol (vapor and liquid droplets). The measurement
technique was demonstrated for an n-decane aerosol with D
50∼3 μ
m in steady and shock-heated flows with a measurement bandwidth of 125 kHz. Laser wavelengths were selected from FTIR measurements
of the C–H stretching band of vapor and liquid n-decane near 3.4 μm (3000 cm
−1), and from modeled light scattering from droplets. Measurements were made for vapor mole fractions below 2.3 percent with
errors less than 10 percent, and simultaneous temperature measurements over the range 300 K<T<900 K were made with errors less than 3 percent. The measurement technique is designed to provide accurate values of temperature
and vapor mole fraction in evaporating polydispersed aerosols with small mean diameters (D
50<10 μ
m), where near-infrared laser-based scattering corrections are prone to error. 相似文献
5.
Photoacoustic spectroscopy (PAS) is one of the important branches of spectroscopy, which enables one to detect light-induced
heat production following the absorption of pulsed radiation by the sample. As2S3, As2Se3 and GeSe2 exhibit a wide variety of photo-induced phenomena that enable them to be used as optical imaging or storage medium and various
electronic devices, including electro-optic information storage devices and optical mass memories. Therefore, accurate measurement
of thermal properties of semiconducting films is necessary to study the memory density. The thermal conductivity of thin films
of As2S3 (thickness 100 μm and 80 μm), As2Se3 (thickness 100 μm and 80 μm) and GeSe2 (thickness 120 μm and 100 μm) has been measured using PAS technique. Our result shows that the thermal conductivity of thicker films is larger than the
thinner films. This can be explained by the thermal resistance effect between the film and the surface of the substrate.
相似文献
6.
High-energy ball milling has been shown to be a promising method for the fabrication of rare earth—transition metal nanopowders.
In this work, NdCo5 nanoflakes and nanoparticles have been produced by a two-stage high-energy ball milling (HEBM), by first using wet HEBM to
prepare precursor nanocrystalline powders followed by surfactant-assisted HEBM. NdCo5 flakes have a thickness below 150 nm and an aspect ratio as high as 102–103; the nanoparticles have an average size of 7 nm. Both the nanoparticles and nano-flakes exhibited high coercivities at low
temperatures, with values at 50 K of 3 and 3.7 kOe, respectively. The high values of coercivity can be attributed to the large
surface anisotropy of nanoparticles that leads to an effective uniaxial-type of behavior in contrast to the planar anisotropy
of the bulk samples. Angle-dependent magnetization measurements at different temperatures were used to determine the spin
reorientation transitions in the nanopowders and nanoparticles. The nanoparticles showed spin reorientation temperatures,
T
SR1 = 276 and T
SR2 = 237 K which are lower when compared with the values of 290 and 245 K, respectively for bulk. 相似文献
7.
G. A. Kozlov 《Physics of Particles and Nuclei》2010,41(6):954-956
A field model for a quark and an antiquark binding is described. Quarks interact via a gauge unparticle (“ungluon”). The model
is formulated in terms of Lagrangian which features the source field S(x) which becomes a local pseudo-Goldstone field of conformal symmetry — the pseudodilaton mode and from which the gauge non-primary
unparticle field is derived by B
μ(x) ∼ ∂μ
S(x). Because the conformal sector is strongly coupled, the mode S(x) may be one of new states accessible at high energies. We have carried out an analysis of the important quantity that enters
in the “ungluon” exchange pattern — the “ungluon” propagator. 相似文献
8.
Yingbang Yao Bernd Ploss C. L. Mak K. H. Wong 《Applied Physics A: Materials Science & Processing》2010,99(1):211-216
BiFeO3 (BFO) ceramics were prepared by a modified solid-state-reaction method which adopts a higher heating/cooling rate during
the sintering process than usually used. It was found that the calcination temperature T
cal (from 400 to 750°C) does not influence the BFO phase formation, while the sintering temperature T
sin (from 815 to 845°C) dominates the phase purity. The optimum sintering temperature was in the range from 825 to 835°C. The
optimized samples exhibit saturated ferroelectric hysteresis loops with a remnant polarization of 13.2 μC/cm2. The measured piezoelectric coefficient d
33 was 45 pC/N. No remnant magnetization was observed in all of the samples. The pyroelectric properties were studied as a function
of temperature and frequency. A pyroelectric coefficient as high as 90 μC/m2 K was obtained at room temperature in the optimized sample. An abrupt decrease of the pyroelectric coefficient was observed
at temperatures between 70 and 80°C. On the basis of our results, BFO may have the potential for pyroelectric applications. 相似文献
9.
The present work reports on the synthesis, characterization and performance of a new metal-containing ionic liquid [(C3H7)2-bim]2[CdCl4] (bim = benzimidazole) as an electrocatalyst for trichloroacetic acid (TCA) and bromate reduction. The structure of Cd(II)-containing
ionic liquid (Cd-IL) was characterized by X-ray crystallography, IR spectroscopy, and elemental analysis. The molecular structure
contains two independent cations of 1,3-dipropyl-benzimidazolium and one anion of CdCl42−. The cadmium atom has a tetrahedral geometry by coordinating to four chlorine atoms. The melting point of Cd-IL is 73 °C.
Electrochemical properties of the Cd-IL have been investigated by preparing bulk-modified carbon paste electrode, and Cd-IL
is used as a binder and an electrocatalyst. This modified electrode has good electrocatalytic activity toward reduction of
TCA and bromate. The detection limit and the sensitivity are 0.01 μM and 102.72 μA μM−1 for trichloroacetic acid detection and 0.003 μM and 496.15 μA μM−1 for bromate detection. This work demonstrates that the Cd-IL may become a new kind of functional material in constructing
chemicals and biosensors. 相似文献
10.
A. Lluveras S. Boularand A. Andreotti M. Vendrell-Saz 《Applied Physics A: Materials Science & Processing》2010,99(2):363-375
This article illustrates the analysis by synchrotron micro-analytical techniques of an azurite painting presenting greenish
chromatic degradation. The challenge of the experiments was to obtain the spatial distribution of the degradation products
of azurite. Copper hydroxychlorides, carbonates and copper oxalates have been mapped by SR FTIR imaging of cross sections
in transmission mode. To complement the information, Py/GC/MS and GC/MS techniques were applied in order to characterize the
binding media and organic materials present as well as their degradation products. Results contribute to a better understanding
of the decay of blue areas in ancient paintings not only from the particular point of view of azurite weathering, but also
by adding information regarding the oxalates’ formation and their distribution in painting samples. Synchrotron radiation
demonstrates its capability for the mapping in painting cross sections. 相似文献
11.
Astrid?Gutierrez-Zepeda Ross?Santell Zhixin?Wu Marishka?Brown YanJue?Wu Ikhlas?Khan Christopher?D?Link Baolu?Zhao Yuan?Luo
Background
Epidemiological studies have associated estrogen replacement therapy with a lower risk of developing Alzheimer's disease, but a higher risk of developing breast cancer and certain cardiovascular disorders. The neuroprotective effect of estrogen prompted us to determine potential therapeutic impact of soy-derived estrogenic compounds. Transgenic C. elegans, that express human beta amyloid (Aβ), were fed with soy derived isoflavones genistein, daidzein and glycitein (100 μg/ml) and then examined for Aβ-induced paralysis and the levels of reactive oxygen species. 相似文献12.
P. Dalmas de Réotier J. P. Sanchez A. Yaouanc S. W. Harris O. Hartmann E. Karlsson R. Wäppling D. Gignoux B. Gorges D. Schmitt Ph. L'Héritier A. Weidinger P. C. M. Gubbens 《Hyperfine Interactions》1991,64(1-4):389-394
Zero-field μSR studies of some hexagonal intermetallic compounds are described. Our LaNI5 data provide information on the muon localisation site. This site could be one of the deuterium sites deduced from neutron
diffraction. A comparison of the temperature dependence of the exponential damping rate, λ(T), of our samples shows that λ(T) is strongly influenced by crystal field effects. The TbNi5 spectra exhibit two components forT<60 K. We discuss the possible explanations of this result. We see a μSR signal below the magnetic phase transition in GdNi5. This makes the study of the spin-lattice relaxation rate possible in the ordered magnetic state. 相似文献
13.
Phase retarders normally show strong wavelength dependence. Achromatic retarders which exhibit nearly identical characteristics
over a wide wavelength spectrum is used in polychromatic light. The present investigation deals with a technique to design
and study the characteristics of an achromatic combination of birefringent plates in 800–2000 nm range. The retarder has been
designed using calcite, crystalline quartz and ADP. The thicknesses of the plates are 19.38 μm, 446.14 μm and 12.57 μm respectively. The new arrangement of three birefringent plates proposed has the promise of producing a zero-order quarter
wave achromatic combination with fairly good accuracy. 相似文献
14.
Zhuming Wang Xijuan Tan Donghua Chen Qiaoli Yue Zhenghua Song 《Journal of fluorescence》2009,19(5):801-808
It was first found that the intrinsic fluorescence of lysozyme at 340 nm can be quenched by cephalosporin analogues through
the static quenching and non-radiative energy transferring procedure. In the acetate buffer solution with pH 7.0 and 298 K,
the quenching fluorescence intensity was in a good linearity over the concentration of drugs in the range of 1–100 μmol L−1, 0.1–100 μmol L−1, 0.5–100 μmol L−1 and 0.05–100 μmol L−1 for cefradine, cefuroxime, cefotaxime and ceftriaxone, respectively. The quenching ability or the binding ability of the
studied drugs followed the pattern: ceftriaxone > cefotaxime > cefuroxime > cefradine, which was close to the order of their
antibacterial ability. The binding parameters including the association constant and the number of binding potential point
were calculated at different temperatures (288, 298 and 308 K), and thermodynamic parameters ΔH°, ΔS° and ΔG° were given. The binding mode of lysozyme with cephalosporins showed that the hydrophobic effect might play a major role.
The binding distance between cephalosporin and tryptophan residue in lysozyme was obtained. The results provided the quantitative
information for the binding of cephalosporin to lysozyme, and it was suggested that the drugs probably bound to the active
site near Trp62 in lysozyme. 相似文献
15.
T. Prokscha E. Morenzoni A. Suter R. Khasanov H. Luetkens D. Eshchenko N. Garifianov E. M. Forgan H. Keller J. Litterst C. Niedermayer G. Nieuwenhuys 《Hyperfine Interactions》2004,159(1-4):227-234
At the Paul Scherrer Institute (PSI, Villigen, Switzerland) the beam of low-energy positive polarised muons (LE-μ
+) with tunable energy between 0.5 and 30 keV allows the extension of the muon-spin-rotation technique (μSR) to studies on thin films and multi-layers (LE-μ
+SR). The range of these muons in solids covers the near-surface region up to implantation depths of about 300 nm. As a sensitive
local magnetic probe with a complementary observational time window to other techniques LE-μ
+SR offers the unique possibility to gain new insights in these nano-scale objects. After outlining the current status of the
LE-μ
+ beam line we demonstrate the potential of this new technique by presenting the results of recent experiments: i) the direct
observation of non-local effects in a superconducting Pb film, ii) the oxygen isotope effect on the in-plane penetration depth
in optimally doped , and iii) the first observation of the conduction electron spin polarisation in the Ag spacer of a Fe/Ag/Fe tri-layer. 相似文献
16.
Liu L. Loh N. H. Tay B. Y. Tor S. B. Yin H. Q. Qu X. H. 《Applied Physics A: Materials Science & Processing》2011,103(4):1145-1151
Micro powder injection molding (μPIM) has been developed as a potential technique for mass production of microcomponents in microsystems due to its shaping
complexity at low cost, in which sintering is a crucial step to dictate the final properties of the microcomponents. In this
paper, final-stage sintering behavior of 316L stainless steel microsize structures prepared by μPIM, φ100 μm and φ60 μm, respectively, was studied. The effect of size reduction in the regime of micrometers on the density of various microsize
structures was investigated. Sintering kinetics of the microsize structures of φ100 μm and φ60 μm were studied based on particle level sintering models. It is found that the microsize structures of φ60 μm had higher density than the microsize structures of φ100 μm given the same sintering condition. The results indicate that size reduction in the regime of micrometers facilitated
densification of microsize structures. The grain growth mechanism of microsize structures varied with size. Whereas the grain
growth of the microsize structures of φ100 μm is governed by surface-diffusion-controlled pore drag, the grain growth of the microsize structures of φ60 μm is controlled by boundary diffusion. During densification, the microsize structures, φ100 μm and φ60 μm, are both controlled by lattice diffusion. The corresponding activation energies are reported in the paper. 相似文献
17.
M. A. Bolshov Y. A. Kuritsyn V. V. Liger V. R. Mironenko S. B. Leonov D. A. Yarantsev 《Applied physics. B, Lasers and optics》2010,100(2):397-407
A tunable diode laser absorption spectroscopy (TDLAS) technique and appropriate instrumentation was developed for the measurement
of temperature and water vapor concentrations in heated gases. The technique is based on the detection of the spectra of H2O absorption lines with different energies of low levels. The following absorption lines of H2O were used: 7189.344 cm−1 (E″=142 cm−1), 7189.541 cm−1 (E″=1255 cm−1), 7189.715 cm−1 (E″=2005 cm−1). Spectra were recorded using fast frequency scanning of a single distributed feedback (DFB) laser. A unique differential
scheme for the recording of the absorption spectra was developed. An optimal technique for fitting the experimental spectra
was developed. 相似文献
18.
Aihui Liang Yueyuan Liang Zhiliang Jiang Hesheng Jiang 《Journal of fluorescence》2009,19(6):1009-1015
The AucoreAgshell (Au@Ag) nanoparticles in size of 30 nm were prepared using 10 nm gold nanoparticles as seeds at 90°C, and were purified by
high-speed centrifugation to remove the excess trisodium citrate to obtain Au@Ag nanoprobe. In the medium of pH 4.0 acetate
buffer solution—7.2 μmol/L H2O2–67 μmol/L Fe(II), Au@Ag nanoparticles exhibited a resonance scattering (RS) peak at 538 nm. Upon addition of Catalase (Ct),
the system produced hydroxyl radical that oxidized the Au@Ag nanoprobe to form the AuAg nanoparticles with partly bare nanogold.
Those AuAg nanoparticles aggregated to large nanoclusters that led to the RS peak wavelength red-shift and its RS peak intensity
enhanced. The catalase activity (C) is linear to the enhanced RS intensity (ΔI) in the range of 6 to 2,800 U/L, with regression equation of ΔI = 0.168 C-0.2, the correlation coefficient of 0.9952, and detection limit of 2.8 U/L. This method was applied to the detection of serum
samples, and the results were agreement with that of the spectrophotometry. A new catalytic mechanism of catalase was proposed
with oxywater principle that was agreement with the results of resonance scattering spectroscopy, absorption spectrophotometry,
transmission electron microscopy and laser scattering. 相似文献
19.
Studies of Benzothiazole and Benzoselenazole Squaraines as Fluorescent Probes for Albumins Detection
Volkova KD Kovalska VB Losytskyy MY Bento A Reis LV Santos PF Almeida P Yarmoluk SM 《Journal of fluorescence》2008,18(5):877-882
Series of squaraine benzothiazole and benzoselenazole dyes were studied as possible fluorescent probes for the detection of
proteins, particularly albumins. It was shown that majority of the studied squaraines give significant fluorescent response
on the human serum albumin (HSA) and bovine serum albumin presence. For squaraine dyes with N-hexyl pendent groups (P-1, P-2, P-3, P-5) about 100−540-fold fluorescence intensity increase upon albumins addition was observed.
At the same time in presence of other proteins, namely insulin, avidin from hen egg white, immunoglobulin G (IgG), carbonic
anhydrase fluorescence enhancement values were considerably lower —up to 43 times in IgG presence. It was noted that generally,
squaraines with long N-hexyl pendent groups demonstrate higher emission increase values upon proteins addition comparing with their analogues with
short N-ethyl tails. It was shown that fluorescence intensity enhancement for benzothiazole squaraine dye P-3, relates linearly to
the HSA concentration over the wide range—from 0.2 to 500 μg/ml. Together with noticeable selectivity of this dye to albumins,
existence of wide dynamic range gives possibility to propose P-3 dye as probe for HSA quantification. 相似文献
20.
It is shown that using position-sensitive detectors in μSR experiments to determine the muon stopping site in a target permits
one to study correlation effects in μSR time histograms produced by the decay of muons stopping in the same domain, i.e. to
obtain time correlators of μSR histograms of decays from a small region. These correlators contain information on the spatial
correlation of magnetic fields in the sample under study. The proposed method (μSR2-technique) allows measuring correlation radii (r
c
) down to 10−5 cm in a bulk sample. Among interesting physical phenomena occuring overr
c≥3×10−6 cm are, for instance, long wavelength fluctuations of the order parameter near the phase transition point in ferromagnets
and antiferromagnets and magnetic field correlations in magnet domains and spin glasses. One may use this method also on heavy-current
accelerators producing pulsed muon beams to investigate the variation in time of spatial correlations in magnets, spin glasses
and superconductors. 相似文献