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91.
92.
Sharmila Muthukrishnan Akhilesh Tanwar Sharankumar G. Shetty Pradeep Singh Yogesha Subbaiah Arun Sikder Radha Kamalakaran Bander Al-Farhood 《Polymer Science Series A》2018,60(3):350-358
In the present study, we have investigated the miscibility, morphology and mechanical behavior of poly(methyl methacrylate) (PMMA) blends with a series of poly(styrene-co-maleic anhydride) (SMA) copolymers containing varying amounts of maleic anhydride (MA) content (from 8 to 26%). The experimental findings have been substantiated by the modeling studies to gain fundamental understanding of the observed phenomena with respect to the miscibility of the PMMA and SMA blends of a given MA content. The morphological differences, molecular weights, domain sizes and mechanical behavior of the blends at a given ratio of PMMA and copolymers have been investigated and a correlation has been made between the morphological understanding to the molecular weights and mechanical properties. The results indicate that the PMMA/SMA blends are miscible only at a certain MA content providing transparent PMMA/SMA blends without affecting any of the enabling properties of PMMA that are of commercial interest through a facile melt mixing process. The surface hardness and % recovery (nano-indentation) of these blends were evaluated as well to gain fundamental understanding of the surface characteristics and mechanicals of the blends. 相似文献
93.
H. Umesha Shetty Eileen M. Daly Nigel H. Greig Stanley I. Rapoport Timothy T. Soncrant 《Journal of the American Society for Mass Spectrometry》1991,2(2):168-173
An automatic reaction control chemical ionization technique in an ion trap detector (lTD) was used to quantitate the levels of the cholinergic drug, arecoline, in plasma of treated patients with Alzheimer’s disease. The chemical ionization reaction was carried out with acetonitrile. The protonated molecules of arecoline (m I z 156) and the internal standard, homoarecoline (m / z 170), were monitored. Human plasma samples were extracted with a readily evaporable solvent mixture, the residues reconstituted and injected along with a tertiary amine-carrier into a capillary gas chromatograph interfaced with the ITD. Standard curves for plasma-extracted arecoline between 20-ng/mL and 156-pg/mL levels were linear (r> 0.9980). Satisfactory precision (relative standard deviation < 20%) and accuracy (relative error < 15%) at the limit of quantitation, 156 pg/mL arecoline, were achieved. Optimal conditions for handling of blood samples obtained by venipuncture were determined. The assay was successfully applied for the therapeutic monitoring of Alzheimer patients treated intravenously with arecoline. 相似文献
94.
<正>Symmetry and pattern are valuable forms of beauty that can be cherished on both the macroscopic and molecular levels.Scientists have always appreciated the intimate connections between symmetry and molecular structures, which is reflected in their design of highly symmetrical compounds.Traditionally, the same story goes with macrocycles, a class 相似文献
95.
Wang Y Men L Vivekananda S 《Journal of the American Society for Mass Spectrometry》2002,13(10):1190-1194
2-Aminoimidazolone and 5-formyluracil are major one-electron photooxidation products of guanine and thymine in oligodeoxynucleotides (ODNs). Herein we report the HPLC isolation and tandem mass spectrometric characterization of ODNs carrying those types of base modifications. Collision-activated dissociation (CAD) of the deprotonated ODN ions leads to cleavages of the 3' C-O bond adjacent to the modification site, which provides enough information for locating the sites of modification. The cleavage 3' to 5-formyl-2'-deoxyuridine is in contrast to the observation that there is no cleavage 3' to an unmodified thymidine under similar conditions. In addition we observed that at high charge states, the loss of 5-formyluracil as an anion and the resulting strand cleavage is predominant over cleavages at other sites. 相似文献
96.
Voice onset time (VOT) is a perceptual cue in voicing contrast of stops in the word initial position. The current study aims
to acoustically and perceptually characterize VOT in one of the major South Indian languages — Tulu. Stimuli consisted of
2 pairs of meaningful words with velar [/p/-/b/] and bilabial stops and [/k/-g/] in the initial position. These words were
uttered by 8 normal native speakers of Tulu and recorded using Praat software. Both spectrogram and waveform views were used
to identify the VOT. For perceptual experiment, 4 adult native speakers of Tulu were asked to identify the stimulus from where
voicing was truncated in steps of 5 to 7 ms till lead VOT was 0 and silence was added after the burst in 5 msec steps till
the lag VOT was 50 msec. The reaction time and the accuracy in identification were measured. Results of acoustic measurement
showed no significant mean difference between lead VOTs of two voiced consonants. However, there was a significant difference
between means of lag VOTs of voiceless consonants. Results of Perceptual measurement showed that as lead VOT reduces, probability
of indentification of /g/ responses reduces; whereas changing VOT had little effect on reaction time and identification of
/b/ responses. These results probably indicate that VOT is not necessary to perceive voiceles constants in Tulu but is necessary
in the perception of voiced consonants. Thus VOT is a constant specific cue in Tulu. 相似文献
97.
Dinesh A. Shetty Travis C. FisherAditya R. Chunekar Steven H. Frankel 《Journal of computational physics》2010,229(23):8802-8822
The subgrid-scale (SGS) eddy-viscosity model developed by Vreman [Phys. Fluids 16 (2004) 3670] and its dynamic version [Phys. Fluids 19 (2007) 065110] are tested in large-eddy simulations (LES) of the turbulent flow in an Re = 12,000 lid-driven cubical cavity by comparison to the direct numerical simulation (DNS) data of Leriche and Gavrilakis [Phys. Fluids 12 (2000) 1363]. This appears to be the first test of this class of model to flows without any homogeneous flow directions, which is typical of flows in complex geometries. Additional LES predictions at Re = 18,000 and Re = 22,000 are compared to the DNS data of Leriche [J. Sci. Comp. 27 (2006)]. The new LES framework yielded excellent agreement for both the mean velocity and Reynolds stress profiles and matches DNS data better than the more traditional Smagorinsky-based SGS models. 相似文献
98.
Natural germanium and selenium consist of, respectively, five and six stable isotopes. Several of these isotopes have considerable abundances and one should expect to observe the bands of at least six isotopic variants of germanium monoselenide (GeSe). In this paper, for the first time, the results of the high-resolution electronic spectrum of the main transition A1Π-X1Σ+ of the specific isotopomer 74Ge80Se, excited in a microwave discharge and recorded in the 33 500-26 000 cm−1 region using a Fourier transform spectrometer, is discussed. From the rotational analysis of 25 bands involving v″ = 0-12 and v′ = 0-7, accurate vibrational and rotational constants of the A1Π state are determined. The present study has revealed perturbations in the v′ = 6 and 7 levels of the A1Π state. 相似文献
99.
Wuosmaa AH Back BB Baker S Brown BA Deibel CM Fallon P Hoffman CR Kay BP Lee HY Lighthall JC Macchiavelli AO Marley ST Pardo RC Rehm KE Schiffer JP Shetty DV Wiedeking M 《Physical review letters》2010,105(13):132501
We have studied the 1?C(d,p)1?C reaction in inverse kinematics using the Helical Orbit Spectrometer at Argonne National Laboratory. Prior studies of electromagnetic-transition rates in 1?C suggested an exotic decoupling of the valence neutrons from the core in that nucleus. Neutron-adding spectroscopic factors give a different probe of the wave functions of the relevant states in 1?C. Shell-model calculations reproduce both the present transfer data and the previously measured transition rates, suggesting that 1?C may be described without invoking very exotic phenomena. 相似文献
100.