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71.
72.
Luis D. Vargas Gustavo A. Chapela Orlando Guzmán Pedro Díaz Leyva Rodrigo Sánchez 《Molecular physics》2020,118(9-10)
We analyse by discrete molecular dynamics the self-assembly of SW trimer particles that contain a different number of attractive and repulsive spheres. They also have different geometries: linear, obtuse, rectangular and equilateral. We identify that some of these molecules exhibit liquid–vapour equilibria while others do not. For all of them, we show the morphological phase diagram built up from the different supra-molecular structures formed by each type of trimer. We simulated 14 different systems with a total of 321 states. The main features of the supra-molecular structures depend only on the composition and geometry of the trimer: triple SW trimers do not form supra-structures, double SW trimers and single SW trimers form monolayers, bilayers and worm-like micelles. The liquid–vapour coexistence properties are also exhibited. These trimers can be used to model complex amphiphiles beyond the standard ones, such as the Gemini and the Bola surfactants as well as colloidal particles. 相似文献
73.
Simple-structured, well-functioned disposable poly(dimethylsiloxane) (PDMS) microchips were developed for capillary isoelectric focusing with whole column imaging detection (CIEF-WCID). Side-by-side comparison of the developed microchips with well-established commercial capillary cartridges demonstrated that the disposable microchips have comparable performance as well as advantages such as absence of lens effect and possibility of high-aspect-ratio accompanied with a dramatic reduction in cost. 相似文献
74.
Ralph Weissleder David D. Stark Guillermo Elizondo Peter F. Hahn Carolyn Compton Sanjay Saini Jack Wittenberg Joseph T. Ferrucci 《Magnetic resonance imaging》1988,6(6):675-681
Thirteen patients with biopsy proven hepatic lymphoma (2 Hodgkin, 11 Non-Hodgkin) and a control group of 15 patients with hepatic metastases were analyzed quantitatively and qualitatively by MRI. Focal hepatic lymphoma was most reliably detected (eight of eight patients) and appeared hypointense relative to liver on T1 weighted (CNR − 7.4 ± 2.3) and hyperintense on T2 weighted (CNR + 8.4 ± 2.9) images. The mean T1 and T2 relaxation times of focal hepatic lymphoma (T1 = 832 ± 234 msec, T2 = 84 ± 16 ms) differed significantly from adjacent non-tumorous liver (T1 = 420 ± 121 ms, T2 = 51 ± 9 ms; p < 0.05), however CNR values and relaxation times were similar to those of hepatic metastases. Diffuse hepatic lymphoma (microscopic periportal infiltration) was undetectable by MRI in three patients by either morphologic features or quantitative criteria. A mixed pattern of hepatic lymphoma (focal lesions and diffuse infiltration) showed focal areas of slightly decreased signal intensity on T1 weighted images (CNR = −1.7 ± 0.4) while T2 weighted images revealed multiple regions of focal hyperintensity (CNR = +13.3 ± 8.4) superimposed on a diffusely hyperintense liver. Our experience demonstrates that either T1 or T2 weighted techniques are useful in detecting focal and that T2 weighted techniques are useful in detecting mixed hepatic lymphoma. Conventional image derived relaxation time measurements and quantitative parameters were of no additional diagnostic value. 相似文献
75.
Guillermina L. Estiú Alicia H. Jubert Jos Molina Juan Costamagna Juan Canales Juan Vargas 《Journal of Molecular Structure》1995,330(1-3):201-210
Semiempirical self-consistent field (SCF) and configuration interaction (CI) calculations of the intermediate neglect of differential overlap (INDO) type are applied to the analysis of the electronic transitions of the hexaazacyclophane base and its Ni and Cu complexes. The ground states (1Ag for the ligand and Ni complex, 2B1g for the Cu complex) are planar structures of D2h symmetry. The low-energy region of the UV-visible spectra, whose analysis may help to recognize the catalytic active sites of the complexes is associated with d → d transitions in the Ni complex, and M → L charge transfer in the Cu complex. 相似文献
76.
77.
J. L. Jiménez Pérez E. Rangel Vargas R. Gutiérrez Fuentes A. Cruz-Orea H. Bautista de León 《The European physical journal. Special topics》2008,153(1):511-513
In this paper we used thermal lens spectrometry to
determine the thermal diffusivity of cheese fats. We have used equal
concentrations of cheese fats from oaxaca, chihuahua, gouda, manchego and
mozzarella cheeses at 42°C temperature. The two lasers
mismatched mode experimental configuration was used with a He-Ne laser, as a
probe beam and an Ar+ laser as the excitation one. The characteristic
time constant of the transient thermal lens was obtained by fitting the
theoretical expression to the experimental data in order to obtain the
thermal diffusivity of the cheese fat samples. This measured thermal
property may contribute to a better understanding of the cheese fats
quality, which is very important in food industry. 相似文献
78.
Finneran JJ Schlundt CE Dear R Carder DA Ridgway SH 《The Journal of the Acoustical Society of America》2002,111(6):2929-2940
A behavioral response paradigm was used to measure masked underwater hearing thresholds in a bottlenose dolphin (Tursiops truncatus) and a white whale (Delphinapterus leucas) before and after exposure to single underwater impulsive sounds produced from a seismic watergun. Pre- and postexposure thresholds were compared to determine if a temporary shift in masked hearing thresholds (MTTS), defined as a 6-dB or larger increase in postexposure thresholds, occurred. Hearing thresholds were measured at 0.4, 4, and 30 kHz. MTTSs of 7 and 6 dB were observed in the white whale at 0.4 and 30 kHz, respectively, approximately 2 min following exposure to single impulses with peak pressures of 160 kPa, peak-to-peak pressures of 226 dB re 1 microPa, and total energy fluxes of 186 dB re 1 microPa2 x s. Thresholds returned to within 2 dB of the preexposure value approximately 4 min after exposure. No MTTS was observed in the dolphin at the highest exposure conditions: 207 kPa peak pressure, 228 dB re 1 microPa peak-to-peak pressure, and 188 dB re 1 microPa2 x s total energy flux. 相似文献
79.
Finneran JJ Schlundt CE Carder DA Ridgway SH 《The Journal of the Acoustical Society of America》2002,112(1):322-328
Auditory filter shapes were estimated in two bottlenose dolphins (Tursiops truncatus) and one white whale (Delphinapterus leucas) using a behavioral response paradigm and notched noise. Masked thresholds were measured at 20 and 30 kHz. Masking noise was centered at the test tone and had a bandwidth of 1.5 times the tone frequency. Half-notch width to center frequency ratios were 0, 0.125, 0.25, 0.375, and 0.5. Noise spectral density levels were 90 and 105 dB re: 1 microPa2/Hz. Filter shapes were approximated using a roex(p,r) function; the parameters p and r were found by fitting the integral of the roex(p,r) function to the measured threshold data. Mean equivalent rectangular bandwidths (ERBs) calculated from the filter shapes were 11.8 and 17.1% of the center frequency at 20 and 30 kHz, respectively, for the dolphins and 9.1 and 15.3% of the center frequency at 20 and 30 kHz, respectively, for the white whale. Filter shapes were broader at 30 kHz and 105 dB re: 1 microPa2/Hz masking noise. The results are in general agreement with previous estimates of ERBs in Tursiops obtained with a behavioral response paradigm. 相似文献
80.
We assessed how listener's judgments of a set of urban sound environments were affected by co-occurring visual settings. In artificial audiovisual environments, subjects rated eight urban sound environments (recordings) when they were associated with five visual settings (four color slides varying in degree of urbanization and a control condition with no slide), along two sound scales (Unpleasant-Pleasant and Stressful-Relaxing). In general, the more urban the visual setting, the more negative the sound ratings. However, this influence depended on the type of sound. It was marked for recordings which did not include human sounds (particularly strong for bird song and weaker for traffic noise), but was absent for all recordings which included human sounds (footsteps and voices). Results are discussed in terms of the degree of matching between visual and sound information, and the degree of implication of the perceiver with these sound environments. 相似文献