Polarization instabilities in a two-photon laser

We describe the operating characteristics of a new type of quantum oscillator that is based on a two-photon stimulated emission process. This two-photon laser consists of spin-polarized and laser-driven 39K atoms placed in a high-finesse transverse-mode-degenerate optical resonator and produces a beam with a power of approximately 0.2 microW at a wavelength of 770 nm. We observe complex dynamical instabilities of the state of polarization of the two-photon laser, which are made possible by the atomic Zeeman degeneracy. We conjecture that the laser could emit polarization-entangled twin beams if this degeneracy is lifted.     

A modeling concept of a mechanical system having a piecewise linear spring property for its diagnosis

Machine condition monitoring and fault diagnosis of rotating machinery are very important because of the wide use of rotating machinery in industry. Couplings and gears are used in many mechanical systems to connect elements and transmit power. The system is usually modeled as a single-degree-of-freedom system with a piecewise linear spring property, where the mass of main machine is only considered. In the present study, the dynamic behavior of a system with an unsymmetrical nonlinearity and a significant mass of the connecting part was investigated both experimentally and by numerical simulation. In the experiment, a 1/3 sub-harmonic oscillation was observed, but this oscillation was not found in the simulation using a single-degree-of-freedom system, in which the mass of the connecting part was ignored. However, when a two-degrees-of-freedom system was used that considered both the mass of the connecting part and the impact property, the 1/3 sub-harmonic oscillation was observed. Thus it is recognized that an adequate mathematical model for diagnosis in the early stage of abnormality must be selected on the basis of the mass ratio between the connecting part and the main body.     

Facile synthesis of core‐surface crosslinked nanoparticles by interblock RAFT polymerization

A new, efficient method for synthesizing stable nanoparticles with poly(ethylene oxide) (PEO) functionalities on the core surface, in which the micellization and crosslinking reactions occur in one pot, has been developed. First, amphiphilic PEO‐b‐PS copolymers were synthesized by reversible addition fragmentation chain transfer (RAFT) radical polymerization of styrene using (PEO)‐based trithiocarbonate as a macro‐RAFT agent. The low molecular weight PEO‐b‐PS copolymer was dissolved in isopropyl alcohol where the block copolymer self‐assembled as core‐shell micelles, and then the core‐shell interface crosslink was performed using divinylbenzene as a crosslinking agent and 2,2′‐azobisisobutyronitrile as an initiator. The design of the amphiphilic RAFT agent is critical for the successful preparation of core‐shell interface crosslinked micellar nanoparticles, because of RAFT functional groups interconnect PEO and polystyrene blocks. The PEO functionality of the nanoparticles surface was confirmed by ¹H NMR and FTIR. The size and morphology of the nanoparticles was confirmed by scanning electron microscopy, transmission electron microscopy, and dynamic laser light scattering analysis. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Effect of artificial mucus properties on the characteristics of airborne bioaerosol droplets generated during simulated coughing

The effect of viscoelastic properties and surface tension of artificial mucus simulant samples on the size distribution and volume concentration of bioaerosol droplets generated during simulated coughing was investigated through in vitro experiments. The mucus simulant samples had viscoelastic properties in a similar range as those of real human airway mucus. The mucus simulant gels were prepared by mixing various proportions of 0.5–1.7% locust bean gum solution and 0.1 M sodium tetraborate (XLB) solution. Surface tension of one set of samples was varied by adding different amounts of SDS (sodium dodecyl sulfate) surfactant while the measurement of surface tension was performed using ADSA (axisymmetric drop shape analysis) method. The viscoelastic properties of the samples were measured using a Bohlin Gemini 200 HR (Malvern, UK) nano-rheometer with peltier plate assembly. An artificial cough machine was used to simulate human cough, generating aerosol droplets in a model trachea attached to the front of the cough machine. The size distribution and volume concentration of the droplets generated through simulated cough were measured using a laser diffraction particle sizer (SprayTec, Malvern, USA). The surface tension was found to have negligible effect on the characteristic of generated droplets within the range of this investigation. The experimental results showed a decrease in particle size as the samples changed from a viscous fluid type to a viscoelastic to an elastic solid type sample. The volume concentration also changed significantly as the viscoelasticity of the samples was varied.     

Gas-chromatographische Bestimmung von Chrom mit Hilfe des Phosphor-Stickstoff-Detektors

Zusammenfassung Die gas-chromatographische Bestimmung von Chrom als Chrom(III)-chelat mit Acetylaceton, Trifluoracetylaceton und Hexafluoracetylaceton als Komplexbildner wird beschrieben. Als Detektor findet der Phosphor-Stickstoff-Flammenionisationsdetektor Verwendung, der zwischen 0,1 und 100 ng linear anzeigt. Die Nachweisgrenze liegt bei 10^–11 g.

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Gas-chromatographic determination of chromium with the phosphorus-nitrogen detector

Summary The gas-chromatographic determination of chromium as Cr(III)-chelate with acetylacetone, trifluoroacetylacetone and hexafluoroacetylacetone as complexing agent is described. The phosphorusnitrogen flame-ionisation detector with a linear response between 0.1 and 100 ng is employed. Limits of detection are in the range of 10^–11 g.

Dem Fonds der Chemischen Industrie sowie dem Land Nordrhein-Westfalen danken wir für die finanzielle Unterstützung dieser Arbeiten.     

Validity and Reliability of the Reflux Symptom Index (RSI)

Laryngopharyngeal reflux (LPR) is present in up to 50% of patients with voice disorders. Currently, there is no validated instrument that documents symptom severity in LPR. We developed the reflux symptom index (RSI), a self-administered nine-item outcomes instrument for LPR. The purpose of this investigation was to evaluate the psychometric properties of the RSI. For validity assessment, 25 patients with LPR were evaluated prospectively before and six months after b.i.d. treatment with proton pump inhibitors (PPI). Each patient completed the RSI as well as the 30-item voice handicap index (VHI). For reliability assessment, the study patients were given the RSI on two separate occasions before the initiation of treatment. Normative RSI data were derived from 25 age-matched and gender-matched controls taken from an existing database of asymptomatic individuals without any evidence of LPR. The mean RSI (+/- standard deviation) of patients with LPR improved from 21.2 (+/- 10.7) to 12.8 (+/- 10.0), and the mean VHI improved from 52.2 (+/- 24.7) to 41.5 (+/- 25.0) after 6 months of therapy (p = 0.001 and 0.065, respectively). Of the three VHI subscales (emotional, physical, functional), only the functional subscale improved significantly (p = 0.037). Patients who experienced a five point or better improvement in RSI were 11 times more likely to experience a five-point improvement in VHI (95% confidence interval = 1.7, 76.8). For reliability assessment, the first and second pretreatment RSIs were 19.9 (+/- 11.1) and 20.9 (+/- 9.6), respectively (correlation coefficient = 0.81, p < 0.001). The single-item correlation coefficients ranged from 0.41 to 0.91 (p < 0.05 for all items). The mean pretreatment RSI in patients with LPR was significantly higher than controls (21.2 versus 11.6; p < 0.001). The mean RSI of patients with LPR after 6 months of PPI therapy approached that of asymptomatic controls (p > 0.05). The RSI is easily administered, highly reproducible, and exhibits excellent construct and criterion-based validity.     

Fibronectin: An Interesting Vocal Fold Protein

A great deal of information is accruing regarding the function of the extracellular matrix. Once thought to be simply a structural entity to surround cells, it is now known to do much more. Fibronectin in particular has received specific attention. Fibronectin is a ubiquitous glycoprotein found most abundantly in the extracellular matrix of regenerating, healing, and embryonic tissue. Vast evidence supports the fact that fibronectin participates in many diverse functions throughout the body that are relevant to vocal fold biology. This article introduces the structure of fibronectin and its isoforms and provides an introduction to some of the many functions it plays. It also reviews the evidence about fibronectin's place in vocal folds and vocal fold pathology. It discusses fibronectin's presence in vocal nodules, vocal polyps, vocal scarring, and Reinke's edema, and reviews the data on its role in mucosal wave impairment. Lastly, it discusses preliminary microarray data that show gene expression for fibronectin to be upregulated in true vocal folds when compared to false vocal folds.     

Short-Term Therapeutic Trial of Proton Pump Inhibitors in Suspected Extraesophageal Reflux

Pharyngoesophageal gastric acid reflux is thought to initiate chronic posterior laryngitis. The gold standard for measuring gastric reflux is dual-channel 24-hour pH monitoring. This is a time-consuming, inconvenient, expensive method that is not available in all areas. New therapeutic regimes that make use of proton pump inhibitors (PPIs) have proven to be therapeutically efficient for control of acid reflux. Twenty-four consecutive patients with chronic voice disorders and signs of posterior laryngitis were selected for therapy. Twenty-four hour pH monitoring was performed independently before the therapy. The trial therapy consisted of all patients receiving pantoprazole, 40 mg once daily for 6 weeks. Immediately following the therapy a statistically significant (p < 0.05) improvement was observed in all patients. This improvement was analyzed retrospectively by comparison with the results of 24-hour pH monitoring. In 71% of the patients the 24-hour pH-monitoring gave a positive result showing a high number of patients with extraesophageal reflux in our study group. Patients with positive results of pH-monitoring responded in a statistically significant manner (p < 0.05) to the pantoprazole therapy, whereas those patients without detected reflux did not. A 3-month follow-up of the patients with a positive result of the pH-monitoring confirmed the improvement. No patients reported adverse effects. A 6-week treatment with pantoprazole can be clinically justified. It helps to save time and reduce costs, allows for selection of reflux-negative patients for alternative therapy, and may prevent inadequate treatment of patients with false-negative pH monitoring. Twenty-four hour pH monitoring is still recommended for patients unresponsive to this trial therapy.     

Electrophysiologic monitoring of the recurrent laryngeal nerves may not predict bilateral vocal fold immobility after thyroid surgery

Two cases of bilateral vocal fold immobility (VFI) after identification and preservation of the recurrent laryngeal nerves (RLNs) required tracheotomy until vocal fold recovery. The first patient underwent thyroid surgery without preoperative or postoperative evaluation of the vocal folds, administration of postoperative intravenous steroids, or electrophysiologic monitoring of the RLNs, whereas the second patient underwent a thyroid procedure in which all of the aforementioned were executed. Preoperative and postoperative clinical evaluation of the RLNs is strongly suggested in patients undergoing thyroid surgery, especially revision surgery. Patients potentially undergoing total thyroidectomy should be counseled about the remote chance of airway obstruction and should be properly selected for this operation. Subclinical stretching of the RLNs or ischemia from the endotracheal tube cuff can result in unilateral VFI, and rarely bilateral VFI, requiring reintubation, tracheotomy, or vocal fold lateralization. Electrophysiologic monitoring may not always predict bilateral VFI.