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51.
用红外光谱法研究麦秸各层面的化学组成 总被引:18,自引:2,他引:18
本文以麦秸为例 ,用红外OMNI采样器研究了麦秸各层面红外光谱的差异 ,并进一步研究了麦草表面在不同的处理条件下 ,表面化学成分的变化规律。实验结果表明 :麦秸表面聚积着大量的SiO2 (~ 1 0 70cm- 1 ~ 80 0cm- 1 ) ,麦秸表皮层脂类物质含量高 (νCO =1 733cm- 1 )。麦秸表面的羟基 (~ 330 0cm- 1 )物质很少。麦秸的中层和内层主要是木素 ( 1 731 ,1 65 0 ,1 5 95 ,1 5 0 5 1 ,1 45 5 ,1 42 5 ,1 2 34,1 0 39和 835cm- 1 )和纤维素类物质 ( 335 0 ,2 935 ,2 85 0 ,1 65 0 ,1 45 5 ,1 430 ,1 367,1 31 7,1 1 60 ,1 0 34和 891cm- 1 )。木素的含量由外向里逐渐减少。麦秸表面的SiO2 是人造板制造中麦草不易粘接的主要原因。用热水处理后 ,表面仅有部分简单的碳水化合物和少量脂类物质溶出 ,而用NaOH处理麦草 ,可使表面的脂类物质和SiO2 溶出 ,便于人造板加工。 相似文献
52.
Janaina S. B. Toledo Vera Lucia D. Tomazella Cleide Mayra M. Lima Matheus H. Felix 《商业与工业应用随机模型》2023,39(2):177-197
In the financial market, it is important to consider that there is a proportion of customers that have settled their debt in time zero, immediately recovering their ability to pay. In this context, in this paper, we propose a survival analysis methodology that allows the insertion of times equal to zero in scenarios where credit risk is observed. The proposed model addresses the survival analysis model of the zero-inflated cure rate which incorporates the heterogeneity of three subgroups (individuals having events in the initial time, and individuals not susceptible and susceptible to the event). In our proposal, all available survival data of customers are modeled considering that the number of competitive causes follows a Poisson distribution and the baseline risk function follows a Gompertz distribution. The model parameter estimation is obtained by the maximum likelihood estimation procedure and simulation studies are conducted to evaluate the estimators' performance. The studied methodology will be applied to a credit database provided by a financial institution in Brazil. 相似文献
53.
de la Vaissiere C Luth V Abrams GS Amidei D Baden AR Barklow T Boyarski AM Boyer J Breidenbach M Burchat P Burke DL Butler F Dillon JW Dorfan JM Feldman GJ Gidal G Gladney L Gold MS Goldhaber G Golding LG Hanson G Haggerty J Herrup D Himel T Hollebeek RJ Innes WR Jaros JA Juricic I Kadyk JA Klein SR Lankford AJ Larsen RR LeClaire BW Levi ME Lockyer NS Matteuzzi C Nelson ME Ong RA Perl ML Richter B Ross MC Rowson PC Schaad T Schellman H Schmidke WB Sheldon PD Trilling GH Yelton JM Wood DR 《Physical review letters》1985,54(19):2071-2074
54.
Mehdi Asghari‐Khiavi Bayden R. Wood Pejman Hojati‐Talemi Andrew Downes Don McNaughton Adam Mechler 《Journal of Raman spectroscopy : JRS》2012,43(2):173-180
Tip‐enhanced Raman scattering (TERS) spectroscopy is a promising technique for nanoscale chemical analysis. However, there are several challenges preventing widespread application of this technology, including reproducible fabrication of efficient TERS probes. These problems reflect a lack of clear understanding of the origins of, and the parameters influencing TERS. It is believed that the coating characteristics at the apex of the tip have a major effect on the near‐field optical enhancement and thus the TERS activity of a metalized probe. Here we show that the aspect ratio of the tip can play a significant role in the efficiency of TERS probes. We argue that the electrostatic field arising from the lightning‐rod effect has a substantial role in the observed TERS effect. This argument is supported by ‘edge‐enhanced Raman scattering’ which is shown for a noble metal film. Furthermore, it is reported that an associated tip‐surface‐enhanced Raman scattering effect can be achieved by using a TERS‐inactive metalized probe on a surface‐enhanced Raman spectroscopy‐inactive roughened surface. This observation can be explained by an interparticle enhancement of the electromagnetic field. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
55.
Curtis P. Rinsland Linda S. Chiou Aaron Goldman Stephen W. Wood 《Journal of Quantitative Spectroscopy & Radiative Transfer》2005,90(3-4):367-375
The average tropospheric volume mixing ratio of CHF2Cl (HCFC-22) has been retrieved from a time series of high spectral resolution ground-based infrared solar absorption spectra recorded with the McMath Fourier transform spectrometer located at the U.S. National Solar Observatory facility on Kitt Peak in southern Arizona (31.9°N, 111.6°W, 2.09 km altitude) for the time period October 1987–November 2002. The retrievals are based on fits to the well-isolated, unresolved 2ν6 Q branch at 829.05 cm−1 and the SFIT2 retrieval algorithm. The measured daily averages show a near linear rise per year in the mean tropospheric volume mixing ratio as a function of time with a best fit yielding an average increase rate of (5.66±0.15) parts per trillion (10−12) by volume per year, corresponding to (6.47±0.17)%yr−1, 1 sigma, at the beginning of the time series. The tropospheric mixing ratios retrieved from the solar spectra have been compared with monthly average surface flask sampling measurements from the Climate Monitoring and Diagnostic Laboratory (CMDL) station at Niwot Ridge, Colorado (40.0°N, 105.5°W, 3013 m altitude), archived measurement from the same location, and early CMDL northern hemisphere Pacific cruise measurements. The average ratio of the retrieved tropospheric mixing ratio relative to the CMDL surface mixing ratio is 1.053 for the overlapping 1987 to 2002 time period. The retrieved mean tropospheric mixing ratio is consistent with the surface measurements within the errors estimated for the remote sensing observations. 相似文献
56.
Levenback BJ Sehgal CM Wood AK 《The Journal of the Acoustical Society of America》2012,131(1):540-549
Antivascular ultrasound consisting of low-intensity sonication in the presence of circulating microbubbles of an ultrasound contrast agent has been demonstrated to disrupt blood flow in solid cancers. In this study a mathematical framework is described for the microbubble-induced heating that occurs during antivascular ultrasound. Biological tissues are modeled as a continuum of microbubble-filled vasculature, cells, and interstitial fluids with compressibility equal to the sum of the compressibility of each component. The mathematical simulations show that the absorption of ultrasound waves by viscous damping of the microbubble oscillations induced significant local heating of the tissue vasculature. The extent and the rate of temperature increase not only depends on the properties of the microbubbles and the sonication parameters but is also influenced markedly by the blood flow. Slow flow conditions lead to higher tissue temperatures due to a stronger interaction between microbubbles and ultrasound and reduced heat dissipation. Because tumors have slower blood flow than healthy tissue, the microbubble-induced ultrasound antivascular therapy is likely to affect cancerous tissue more extensively than healthy tissue, providing a way to selectively target the vasculature of cancers. 相似文献
57.
Sam V. Nablo James C. Wood Jr. Marc F. Desrosiers Vitaly Yu. Nagy 《Radiation Physics and Chemistry》1998,52(1-6):479-485
A small capacity (100 g.s−1) pilot system is described for presentation of powders and fine aggregates at high velocity, to an electron beam. Electron beam dose rate is continuously monitored in real time, while the thickness of the fluidized bed used to pneumatically transport the product can be monitored and controlled using beta-gauge techniques. Using electron paramagnetic resonance (EPR) techniques, alanine power mixed with the product is used for precise determination of dose delivered to the powder stream. Thin film dosimeters transported in the bed are also used for dose determination. Results with a variety of products are presented using both dose rate and velocity as the independent variables. Lethality data for the bioburdens present in several powdered foodstuffs are discussed. 相似文献
58.
Arran R. Wood Nicolas Benedetto Nigel Hooker Edward Scullion Paul A. Smith John F. Watts 《Surface and interface analysis : SIA》2008,40(10):1409-1414
The design philosophy and implementation of an ultra high vacuum (UHV), PC controlled, automated in situ fracture stage for a surface analysis system is described. ToF‐SIMS spectra are shown to illustrate the improvement in spectral quality obtained from micro‐compact tension (CT) tests of polymer matrix fracture surfaces produced using the fracture stage in UHV compared to those obtained from a sample tested at air. This system is flexible in that by changing the capacity of the load cell it is possible to reduce or increase maximum loads as the specimen type and material demands. The stage has been designed with instrumental flexibility in mind, utilising commercial SEM‐stub type sample mounts, and can thus be used for AES/SAM and XPS investigations, as well as ToF‐SIMS analysis, in the authors' laboratory. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
59.
Jiang JX Su F Niu H Wood CD Campbell NL Khimyak YZ Cooper AI 《Chemical communications (Cambridge, England)》2008,(4):486-488
High surface area porous poly(phenylene butadiynylene) networks were obtained (BET surface area up to 842 m(2) g(-1)) by the palladium-catalyzed homocoupling of 1,3,5-triethynylbenzene and 1,4-diethynylbenzene. 相似文献
60.
Brown PS Berson A Talbot EL Wood TJ Schofield WC Bain CD Badyal JP 《Langmuir : the ACS journal of surfaces and colloids》2011,27(22):13897-13903
The impact of picoliter-sized water droplets on superhydrophobic CF(4) plasma fluorinated polybutadiene surfaces is investigated with high-speed imaging. Variation of the surface topography by plasmachemical modification enables the dynamics of wetting to be precisely controlled. Final spreading ratios as low as 0.63 can be achieved. A comparison of the maximum spreading ratio and droplet oscillation frequencies to models described in the literature shows that both are found to be much lower than theoretically predicted. 相似文献