Influence Of Fine Structure Research Articles

Observation of microcavity fine structure

We observe fine structure in the resonance spectra of optical microcavities. We identify the polarization-resolved modes in the spectrum and find that resonance frequencies split in accordance with the theoretical prediction. The observed fine structure is dominantly caused by an optical spin-orbit coupling and non-paraxial propagation and reflection. Both effects are intrinsic, i.e. present in an ideal rotation-symmetric system, and scale inversely proportional to the mirror radius of curvature. For cavities with a small radius of curvature, the influence of fine structure on the resonance spectrum is important and unavoidable and should thus be taken into account.

Influence of Fine Structure on the Variations of Thermal and Mechanical Properties in Flax Fibers Modified with Different Alkaline Treatment Conditions

ABSTRACT The alkaline treatment condition plays a crucial role in governing the ultimate properties of flax fibers. In this study, flax fibers were modified with mild alkalization and severe mercerization conditions to give fundamental insight into how the molecular-scale changes in cell wall fine structure and cellulose supramolecular structure can affect the macroscopic properties of fibers. SEM, FTIR, XRD, TGA, and DSC techniques were employed to characterize the variations in morphology, composition, crystalline structure, and thermal properties of fibers. Also, tensile tests evaluated their reinforcing performance in polypropylene-based composites. The results indicated that alkalization in 5% (w/v) NaOH solution preserved the tensile properties of fibers, shifted their thermal decomposition temperature from 198 to 254°C, and effectively decreased their moisture absorption content by 18%. The improvements primarily originate from the partial removal of noncellulosic constituents and promoted crystallinity of native cellulose Iβ structure. However, mercerization in 20% (w/v) solution significantly reduced the rigidity of fibers in the longitudinal direction. Furthermore, it decreased the moisture absorption only by 6% and shifted the thermal degradation to 275°C. The excessive elimination of noncellulosic constituents and the polymorphic transformation, which led to a weaker hydrogen bonding network in the cellulose II region, accounts for these changes.

精细结构混合速率对激光二极管抽运碱金属蒸气激光器性能的影响

精细结构混合速率对激光二极管抽运碱金属蒸气激光器性能的影响

408 Ti-15-3-3-3合金の高強度化に伴う微細組織の影響に関する研究(機械材料・材料加工IV)

408 Ti-15-3-3-3合金の高強度化に伴う微細組織の影響に関する研究(機械材料・材料加工IV)

Influence of fine structure and envelope variability on gap-duration discrimination thresholds

The goal of the study was to investigate whether the temporal resolution of the auditory system is influenced by the variability of the stimulus envelope. To do so, the ability to detect an increment in the duration of a temporal gap (the test gap) was measured with an adaptive 3-IFC procedure. The stimulus consisted of a series of 10-ms broadband noise pulses. The pulses were separated by a 10-ms silent period, or temporal gap. In the main experiments, the test gap was either the first or the last gap in a series of 21 pulses. The variability in the stimulus’ envelope was controlled directly by applying a jitter to the onset of the individual pulses in the pulse trains. Additionally, the stimuli were presented with different fine structure variabilities which also induced differences in the variability of the envelope. The gap-discrimination thresholds for the jittered noise pulse trains showed strong dependence on the amount of jitter as long as the jitter was applied randomly leading to a different pattern for every stimulus. When the jitter was applied as a frozen jitter resulting in a constant pattern of pulses, the thresholds did not increase significantly. A similar result was obtained for the different fine structure variabilities. A frozen fine structure led to thresholds about 1 ms lower than those obtained with random noise stimuli. A measure for the envelope variability was provided by calculating the variances of the envelope spectrum of the gammatone-filtered stimuli. The results of the calculations show a qualitative correspondence to the experimental results.

Spectroscopic measurements of electron densities and gas temperatures in deuterium lamps

Plasma diagnostics results of electron densities and gas temperatures in commercial low-pressure deuterium lamps at current densities from 38 A/cm(-2) to 306 A/cm(-2) are presented. These plasma parameters are obtained by comparing measured and calculated Balmer line profiles, taking into account Stark broadening, Doppler broadening, and the influence of fine structure and the apparatus profile. Results for the plasma spot show a steady increase of electron density from 1.6 x 10(13) cm(-3) to 5.0 x 10(13) cm(-3) and of gas temperature from 1800 to 6800 K.

Influence of fine structure on the torsional fatigue behavior of poly(ethylene terephthalate) fibers

Three experimental poly(ethylene terephthalate) fibers have been spun and then drawn at three different temperatures(70°C, 90°C, and 110°C) in such a way that the drawn fibers possess different orientations and crystallinities but retain the same diameters. Wide angle X-ray diffraction and birefringence measurements have been used to characterize orientation and crystallinities of the fibers. The influence of fine structure on the torsional fatigue behavior of the melt spun and drawn PET fibers has been studied by subjecting them to 1.7 Hz torsional cyclic deformation at various amplitudes. Fracture morphology was found to be strongly influenced by the degree of orientation and crystallinity. Highly oriented and crystalline structures tended to separate into a highly fibrillated structure. Fibers of low draw ratio exhibited initial deterioration of the surface structure with the generation of transverse cracks (perpendicular to the fiber axis). Subsequent torsional loading of the structure generated an increase in longitudinal cracks which finally resulted in the catastrophic failure of the fiber. The extent of fibrillation was found to be a function of draw ratio (orientation) and crystallinity. The amplitude of torsional strain was also found to have an effect on the intensity of fibrillation and the number of cycles to fiber failure.

Influence of fine structure on the pyrolysis of cellulose. III. The influence of orientation

AbstractThe effects of orientation upon the pyrolysis of cellulose were investigated by using a series of rayon fibers which differed only in orientation. The initial weight loss seen in low‐temperature vacuum pyrolysis is due to crosslinking in the less ordered regions and was shown to be a first‐order reaction whose rate varies directly with the degree of orientation. The extent of this reaction decreases with increasing orientation and is directly related to the amount of char formed at higher temperatures. The bulk pyrolysis rate increases with increasing orientation. DSC, air pyrolysis rates, and levoglucosan formation were also studied.

The influence of fine structure on the pyrolysis of cellulose. II. Pyrolysis in air

AbstractThe pyrolysis of purified celluloses in air at 251°C was studied. The pyrolysis was found to obey first‐order kinetics, and the rate constants correlated with the crystallinities, orientations and accessibilities of the samples. The results are interpreted in terms of an oxygen‐catalyzed decomposition, with the accessibility of oxygen to the cellulose determining the rate of pyrolysis. The production of levoglucosan under conditions approaching combustion was shown to be a function of the crystallinity and orientation of cellulose. Some levoglucosan appears to be produced from the less ordered regions.

The influence of fine structure on the pyrolysis of cellulose. I. Vacuum pyrolysis

AbstractThe effects of crystallinity, orientation and degree of polymerization on the vacuum pyrolysis of cellulose have been investigated. Natural, modified and manmade celluloses were characterized and the kinetics of their pyrolysis at 251°C studied. The high‐temperature pyrolysis of these samples was also investigated by means of DSC and TGA. At 251°C all of the samples showed a rapid, initial weight loss followed by a linear (weight loss)1/2 versus time dependency. Both the initial weight loss and the subsequent reaction rate were dependent upon the crystallinity of the sample. The reaction rate was shown to be inversely proportional to (DP)1/2 and related to the orientation. Effects of crystallinity and orientation could also be seen in the DSC thermograms and in the apparent energies of activation. Results are interpreted in terms of probable mechanisms of the uncatalyzed pyrolysis of cellulose.