ToF‐SIMS and principal component analysis: Effect of film thickness on crystal surfaces of polymers

The effect of film thickness on the structural conformation of the surfaces of the amorphous state, edge‐on lamellae and flat‐on lamellae of a semiflexible polymer, poly(bisphenol‐A‐etheroctane), was investigated by time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) with the aid of principal component analysis (PCA). PCA results empirically indicate that a structurally regular polymer surface was obtained with the formation of the flat‐on lamellae from the amorphous state at a low degree of supercooling. A higher concentration of end group and cilium ion fragments, which are indicative of free chain ends, was observed on the edge‐on lamellar surfaces than on the amorphous and the flat‐on lamellar surfaces. This finding was attributed to the fact that the lateral surface of the edge‐on lamellae contains many growth fronts, leaving behind a large number of uncrystallized chain remnants on the surfaces. Structural disorder was facilitated on both edge‐on and flat‐on lamellar surfaces as the film thickness decreased. Hence, this PCA study offers new insights into the nonequilibrium nature of polymer crystals and the mechanism of polymer crystallization in thin and ultrathin films. Copyright © 2010 John Wiley & Sons, Ltd.     

Effects of prolonged oral reading on F0, SPL, subglottal pressure and amplitude characteristics of glottal flow waveforms

The effects of prolonged (5x45 minute) reading (vocal loading) on fundamental frequency (F0), sound pressure level (SPL), subglottal (intraroral) pressure (p), and two glottal flow waveform parameters (AC amplitude of glottal flow, f, and negative peak amplitude of differentiated flow (d) of normal female and male subjects (N = 80) were studied. Two rest (morning and noon) and three loading (two in the morning and one in the afternoon) samples were recorded and analyzed. The glottal waveforms were obtained by inverse filtering of the acoustic pressure waveforms of speaking voice samples. The analyses were based on measurement and inverse filtering of the first stressed syllable of "paappa" words repeated 3x5 times for normal, as soft as possible, and as loud as possible phonation. In normal phonation the parameter values changed statistically significantly due to loading. In many cases the values obtained in the morning samples changed after the first loading session. This is interpreted as a vocal "warming-up effect." Especially in soft phonation p, d, and f were sensitive indicators of vocal loading. In both normal and soft phonation, the SPL, p, d, and f values tended to rise due to prolonged reading in the morning and afternoon samples, indicating increased effort (normal phonation) and a rise in the phonatory threshold (soft phonation). The lunch break vocal rest ("rest effect") considerably affected the parameter values in many cases.     

Raman longitudinal acoustic mode studies of poly(ethylene oxide) and α,ω-methoxylated poly(ethylene oxide) fractions during isothermal crystallization from the melt

Raman longitudinal acoustic mode (LAM) spectra have been obtained during isothermal crystallization from the melt at various temperatures of a poly(ethylene oxide) (PEO) fraction of molecular weight about 3000 and an α,ω-methoxylated fraction (MPEO) derived from it. For both fractions, we find that noninteger fold (NIF) chains are formed in the initial stages of crystallization. With time, and more rapidly at higher crystallization temperatures, the NIF chains transform into integer-fold (IF) structures. The final morphologies of the two fractions are similar, consisting of IF mixed-crystal lamellae composed mainly of extended (E) chains with embedded once-folded (F2) chains. This solid-state transformation from the NIF state may proceed through the F2 state. The effect of hydrogen bonds in the case of PEO is not to change the transformation process but to slow it when compared to MPEO. Comparison with small-angle x-ray scattering (SAXS) data indicates that in both cases the NIF chains are tilted to the lamellar surface and that the tilt from perpendicular eventually disappears as IF chains form at the later stages of crystallization. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1117–1126, 1997     

基于光谱识别技术的土壤铁锰结核对镉的吸附行为研究

铁锰结核是具有高反应活性的矿物复合体;与海洋铁锰结核不同,土壤铁锰结核常在干湿交替、水气干扰条件下存在,形成了独具特色的地球化学特征.作为土壤"新生体",不同地区铁锰结核常表现出较大差异.研究典型区域土壤铁锰结核与重金属的结合行为,有助于深入了解铁锰结核的微生态属性,对于后续土壤的开发利用、保育改良、污染修复等都具有战...     

Material multipole mechanics of elastic dielectric composites

The overall mechanical and electrical behaviors of elastic dielectric composites are investigated with the aid of the concept of material multipoles. In particular, by introducing a statistical continuum material multipole theory, the effects of the electric-elastic interaction and the microstructure (size, shape, orientation,...) of inhomogeneous particles on the overall behaviors of the composites can be obtained. A basic solution for an ellipsoidal elastic inhomogeneity with electric polarization in an infinite elastic dielectric medium is first given, which shows that classical Eshelby ’s elastic solution is modified by the presence of electric-elastic interaction. The overall macroscopic constitutive relations and their overall macroscopic material parameters accounting for electroelastic interaction effect are then derived for the elastic dielectric composites. Some quantitative calculations on the problems with statistical anisotropy, the shape effect and the electric-elastic interaction are finally given for dilute composites.     

γ脉冲射线束在大气中的输运计算方法

在γ脉冲射线束测量中,束流波形是由许多不同能量的γ粒子叠加而成的,在大气介质传输中,由于γ粒子与空气原子的相互作用,测点的γ能通量强度随时间变化的波形、同源点的γ强度波形相比,在较大测点距离的情况下就会产生畸变。讨论了γ射线在大气中输运的传输函数以及用褶积计算测点γ能通量强度波形的方法,给出了解析表达式,对典型的γ源脉冲波形输运不同距离,计算了大气输运对测量的影响。最后讨论了减小或避免波形畸变的方法。     

Electrical characteristics of silicon-nodule-related via failures observed in aluminum-silicon interconnects

We have evaluated the electrical characteristics of silicon-nodule-related via failures in the aluminum interconnects of silicon integrated circuits. Current-voltage measurements indicated that the conduction mechanism follows Ohm's law. The resistance was 1.5–3 kΩ for a silicon nodule at a via of 1.0 μm × 1.0 μm. When the applied voltage was 3–6 V, the resistance decreased abruptly. This transition (abrupt decrease in resistance) was irreversible. We think that the resistance of 1.5–3 kΩ and the transition voltage of 3–6 V are two factors characterizing the silicon nodule. We can explain these values by assuming that aluminum in the silicon nodules at a solubility limit concentration acts as an acceptor. Received: 22 February 1999 / Accepted: 30 June 1999     

Medialization Laryngoplasty With Gore-Tex: An Animal Study

Vocal cord paralysis is a disease that can cause voice disability and aspiration problems. Expanded polytetrafluoroethylene (ePTFE; Gore-Tex) has been widely used in cardiovascular and plastic surgery; however, its biocompatibility and safety have not been established precisely in the larynx. In this study, the biocompatibility and safety of ePTFE used in vocal cord medialization in the rabbit larynx were assessed. Type 1 thyroplasty with Gore-Tex was performed on one side of the larynx in eight rabbits. A sham procedure was applied on the contralateral side of their larynx. The rabbits were sacrificed after 6 months, and macroscopic and microscopic evaluations and comparisons were performed. No significant inflammatory response to Gore-Tex or displacement of the implant was seen. There was only a tiny fibrotic capsule surrounding the material in each specimen. Intense eosinophilic cell infiltration was seen surrounding one rabbit specimen. Gore-Tex seems to be a biocompatible, stable, and reversible material that can be safely used in laryngeal framework surgery.     

Vocal Fold Polyp in a Professional Brass/Wind Instrumentalist and Singer

Wind instrumentalists, especially brass players, and singers share common factors, including vocal tract shape, function and pressure, vocal fold opening and closure, breath vector of force and air flow rates. To understand the mechanism and function of the vocal folds with a pathological lesion, it is necessary to visualize the differing interactions of the vocal tract during wind and brass instrument playing and in singing. A school band director, singer, wind and brass instrumentalist, was referred by musician colleagues with intermittent dysphonia, aphonia, and inability to sing high notes. Simultaneous videolaryngoscopy, with and without stroboscopy, and external video examination were documented. An hourglass glottis with a sessile, cystic polyp of the left vocal fold were recorded and studied during phonation and the playing of 3 instruments. The techniques of glottic opening, closure, configuration and function varied with the type of instrument and phonatory function. Singing was adversely affected by the vocal fold polyp but no harmful interaction occurred during wind/brass instrument playing. Down-stream loading in singers is at the laryngeal level and in wind/brass instrumentalists is at the embouchure. Preoperative voice therapy, phonomicrosurgery, and postoperative voice rest followed by voice therapy, succeeded in restoring her combined wind/brass instrumental and singing career.     

Voice research: So What? A clearer view of voice production, 25 years of progress; the speaking voice

The past 25 years has yielded an impressive growth in our knowledge of vocal function. Interdisciplinary research cooperation in areas of laryngeal histology, vocal aerodynamics and acoustics, vocal fold vibratory characteristics, neurolaryngology, and phonatory models has led to a clearer view of voice production. This article offers a brief review of the progress that has been made in our understanding of the speaking voice and relates this knowledge to clinical practice. The importance of utilizing voice research to confirm traditional management techniques and to develop new physiologically based management approaches is also stressed.