Liquid core waveguide-based optical spectrometry for field estimation of dissolved BTEX compounds in groundwater: A feasibility study

The utility of a liquid core waveguide (LCW) system for acting as a sentry monitor for compounds such as benzene, toluene, ethylbenzene, xylene (BTEX) in water was examined. A vapor-permeable LCW suitable for long path length absorbance spectroscopy based on a Teflon AF 2400 tube was fabricated. Multiwavelength spectroscopy in the near-UV was carried out using a fiber optic-based flashlamp-photodiode array (PDA) combination with hexane as the solvent in the waveguide core. Using multicomponent calibration, quantitation of benzene and toluene accurate to 6±5% could be conducted at sub-mg l⁻¹ levels in mixtures after a sampling period of 10 min.     

Study of the luminescent behavior of Spectrolite + Teflon pellets in 90Sr + 90Y beams

The Spectrolite, from the silicate family, a variety of Labradorite, was already studied in relation to its thermoluminescence (TL) and optically stimulated luminescence (OSL) responses, in high-dose gamma radiation fields; the results indicated their good application as gamma radiation detectors. In the present work, the analyses performed to investigate powdered Spectrolite are presented, by means of the XRD, SEM and EDX techniques. The luminescent behavior of Spectrolite + Teflon samples, in the concentration of 1:1, was studied in beta radiation beams (⁹⁰Sr + ⁹⁰Y), using the luminescent phenomena of TL and OSL. The results showed adequate TL and OSL reproducibility of the samples; the dose–response curves for both techniques presented a linear behavior in a range from 0.5 Gy to 1 kGy, and the fading showed that after 150 h there were 46.7% and 31.6% of the remaining signal of samples for TL and OSL responses, respectively. Therefore, the Spectrolite + Teflon pellets may be used in beta radiation dosimetry.     

Fluoride ions at the Cu–fluoropolymer interface

Nanometer thick films of sputtered and evaporated Cu were deposited on the surfaces of the fluoropolymers poly(tetrafluoroethylene) (PTFE), poly(tetrafluoroethylene‐co‐hexafluoropropylene) (FEP) and poly(tetrafluoroethylene‐co‐perfluoropropyl vinyl ether) (PFA) and studied by both angle‐resolved XPS at takeoff angles of 10°, 45° and 80° and in situ argon ion etching. Higher yields of the fluoride ion to fluoropolymer ratio were detected for sputtered than evaporated Cu. PFA and FEP show enhanced interaction with sputtered Cu to produce fluoride ions relative to the more polycrystalline PTFE. At intermediate depths (takeoff angle of 45°), PFA and FEP exhibit the strongest fluoride F 1s signals compared with the fluoropolymer peaks. The amount of fluoride ion detected reaches a maximum after brief Ar ion etching and then decreases with prolonged etching. Compared with untreated fluoropolymers, improved adhesion of evaporated Cu was observed on the fluoropolymer surfaces that were argon ion etched to expose fluoride ions. Copyright © 2013 John Wiley & Sons, Ltd.     

Simple and robust near-infrared spectroscopic monitoring of indium-tin-oxide (ITO) etching solution using Teflon tubing

The ability to monitor etching solutions using a spectroscopy directly through existing Teflon lines in electronic industries is highly beneficial and offers many advantages. A monitoring method was developed using near-infrared (NIR) measurements with Teflon tubing as a sample container for the quantification of components in the indium-tin-oxide (ITO) etching solution composed of hydrochloric acid (HCl), acetic acid (CH₃COOH) and water. Measurements were reproducible and it was possible to use the same calibration model for different Teflon tubings. Even though partial least squares (PLS) calibration performance was slightly degraded for Teflon cells when compared to quartz cells of the similar pathlength, the calibration data correlated well with reference data. The robustness of Teflon-based NIR measurement was evaluated by predicting the spectra of 10 independent samples that were collected using five different Teflon tubes. Although, two Teflon tubes were visually less transparent than the other three, there was no significant variation in the standard error of predictions (SEPs) among the five Teflon tubes. Calibration accuracy was successfully maintained and highly repeatable prediction results were achieved. This study verifies that a Teflon-based NIR measurement is reliable for the monitoring of etching solutions and it can be successfully integrated into on-line process monitoring.     

Avoidance and treatment of complications of teflon injection of the vocal cord

The best way to avoid complications with Teflon injection of the vocal cord, as with any other surgical procedure, is proper patient selection and technique. Indications, techniques, and treatment of complications are discussed     

Superhydrophobic PTFE Surfaces by Extension

Summary: A rather simple but yet effective way to achieve a superhydrophobic film by extending a Teflon film is proposed. The water‐contact angle can be increased from 118 to 165° by extending to ca. 190%. The fibrous crystals and the increasing distance between the fibrous crystals are believed responsible for the high water‐contact angle. It indicates that the density of the aligned microstructures is very important for the superhydrophobicity.

Water‐contact angle and the corresponding shapes of water droplets as a function of extension ratio of Teflon tape.     

Protein identification with Teflon as matrix-assisted laser desorption/ionization sample support

Protein identification is a critical step in proteomics, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) plays an important role in that identification. Polytetrafluoroethylene (Teflon) was tested as a new MALDI sample support to improve protein identification. The tryptic peptides obtained from a model protein were bound to the surface of a modified MALDI sample holder via the hydrophobic interactions that occur between the Teflon surface and the peptide ion-pairs, and the affinity of alpha-cyano-4-hydroxycinnamic acid for the peptides. During that surface-binding step, the peptide mixture was also desalted and concentrated. A greater number of matched peptides and a larger sequence coverage were obtained for the proteins when Teflon was used as the sample support compared with conventional sample preparation methods and a stainless-steel surface. In addition, the characterization of a small amount of protein was improved with Teflon. Nine silver-stained protein spots obtained from 2-D gel of a human cerebrospinal fluid (CSF) proteome were identified by this method. Among the nine protein spots, peptide 6:c3c fragment and procollagen c-proteinase enhancer were not annotated in any published 2-D map of human CSF. A Teflon MALDI sample support is a low-cost, simple, and effective method that can be used to improve the quality of the MALDI mass spectrum of a complex tryptic peptide mixture, and to achieve a higher level of reliability and success in protein identification.     

A new quantitative Raman measurement scheme using Teflon as a novel intensity correction standard as well as the sample container

A novel and reliable quantitative Raman measurement scheme has been proposed for the analyses of ethanol and isopropanol solutions. Teflon tubing was employed as an effective intensity correction standard as well as the sample cell. This allowed for the synchronous collection of the mixed Raman spectrum from the Teflon standard and the sample without any extra optical configuration. A non‐overlapping Teflon band was used as the standard peak to correct the Raman intensity changes resulting from laser power variations. In addition to the use of Teflon tubing,a wide area illumination (WAI) scheme was employed, which made the laser illumination into a circle of 6 mm diameter (area: 28.7 mm²), to cover a wide sample area. The WAI scheme improved the reliability of the Raman measurement by significantly increasing the reproducibility of the sampling owing to a decreased sensitivity to sample placement with respect to the focal plane as well as a wider sample coverage area. The resulting Raman spectra were more reproducible and more representative of the correct sample composition. Overall, a superior prediction performance was achieved using the WAI scheme compared to the conventional Raman collection method. The proposed system has great potential for use in the quantitative analysis of diverse liquid samples with good reproducibility. Copyright © 2006 John Wiley & Sons, Ltd.     

Triple quantum nutation in the two-level NMR system in the rotating frame

The authors present the detailed theory and the new results associated with the triple quantum (TQ) nutation and the line narrowing effect of the TQ resonance in the two-level NMR system which we reported previously. The TQ resonance is induced in the spin-locked system by the oscillating field produced by the sinusoidal phase modulation (PM) of the RF field. The theory predicts that the TQ nutation is accompanied by several higher frequency oscillations and we detected them experimentally by improving the detection system. These higher frequency oscillations are due to the fluctuation of the angle between the transverse or effective field causing the TQ nutation and the RF field. We obtain the result that the modulation index 2phim of the PM is the key parameter that essentially controls the conditions of the TQ resonance and the narrowing effect. Under the exact TQ resonance, the ratio of the TQ resonance frequency to the Larmor frequency of the RF field depends only on phim, and the secular part of the magnetic dipole Hamiltonian of a like spin system in the triply rotating frame disappears at a particular value of phim. The condition is different from that of the well-known magic angle condition.     

Traumatic vocal fold avulsion injury in a newborn

A full-term newborn developed respiratory compromise in the immediate postparturition period requiring urgent intubation. Evaluation of post-extubation stridor later the same day revealed an avulsion injury extending from the left vocal fold into the lateral glottic musculature. Primary repair was accomplished with anatomic realignment of the torn vocal fold and muscle. Endotracheal intubation was utilized for stenting and the patient was extubated following 3 days of paralysis with sedation. Follow-up examination revealed a reparative granuloma, which was lasered. Eight-week follow-up examination revealed normal vocal fold architecture. At 18 months the patient continues to have a normal voice and normal laryngeal development.