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1.
PLoS One ; 18(2): e0281877, 2023.
Article in English | MEDLINE | ID: mdl-36795744

ABSTRACT

In this study, 23 subjects produced cyclic transitions between rounded vowels and unrounded vowels as in /o-i-o-i-o-…/ at two specific speaking rates. Rounded vowels are typically produced with a lower larynx position than unrounded vowels. This contrast in vertical larynx position was further amplified by producing the unrounded vowels with a higher pitch than the rounded vowels. The vertical larynx movements of each subject were measured by means of object tracking in laryngeal ultrasound videos. The results indicate that larynx lowering was on average 26% faster than larynx raising, and that this velocity difference was more pronounced in woman than in men. Possible reasons for this are discussed with a focus on specific biomechanical properties. The results can help to interpret vertical larynx movements with regard to underlying neural control and aerodynamic conditions, and to improve movement models for articulatory speech synthesis.


Subject(s)
Larynx , Speech , Male , Female , Humans , Phonetics , Larynx/diagnostic imaging , Movement , Videotape Recording
2.
Ann Biomed Eng ; 50(12): 1837-1845, 2022 Dec.
Article in English | MEDLINE | ID: mdl-35773416

ABSTRACT

Coronary artery disease represents a leading cause of death worldwide, to which the coronary artery bypass graft (CABG) is the main method of treatment in advanced multiple vessel disease. The use of the internal mammary artery (IMA) as a graft insures an improved long-term survival, but impairment of chest wall perfusion often leads to surgical site infection and increased morbidity and mortality. Infrared thermography (IRT) has established itself in the past decades as a non-invasive diagnostic technique. The applications vary from veterinary to human medicine and from head to toe. In this study we used IRT in 42 patients receiving CABG to determine the changes in skin surface temperature preoperatively, two hours, 24 h and 6 days after surgery. The results showed a significant and independent drop of surface temperature 2 h after surgery on the whole surface of the chest wall, as well as a further reduction on the left side after harvesting the IMA. The temperature returned to normal after 24 h and remained so after 6 days. The study has shown that IRT is sufficiently sensitive to demonstrate the known, subtle reduction in chest wall perfusion associated with IMA harvesting.


Subject(s)
Coronary Artery Disease , Thoracic Wall , Humans , Thoracic Wall/diagnostic imaging , Thoracic Wall/surgery , Coronary Artery Bypass/methods , Diagnostic Imaging , Perfusion
3.
J Acoust Soc Am ; 151(1): 45, 2022 01.
Article in English | MEDLINE | ID: mdl-35105025

ABSTRACT

The periodic repetitions of laryngeal adduction and abduction gestures were uttered by 16 subjects. The movement of the cuneiform tubercles was tracked over time in the laryngoscopic recordings of these utterances. The adduction velocity and abduction velocity were determined objectively by means of a piecewise linear model fitted to the cuneiform tubercle trajectories. The abduction was found to be significantly faster than the adduction. This was interpreted in terms of the biomechanics and active control by the nervous system. The biomechanical properties could be responsible for a velocity of abduction that is up to 51% higher compared to the velocity of adduction. Additionally, the adduction velocity may be actively limited to prevent an overshoot of the intended adduction degree when the vocal folds are approximated to initiate phonation.


Subject(s)
Gestures , Larynx , Humans , Larynx/diagnostic imaging , Movement , Phonation/physiology , Vocal Cords/physiology
4.
J Org Chem ; 75(18): 6229-35, 2010 Sep 17.
Article in English | MEDLINE | ID: mdl-20718453

ABSTRACT

Consecutive ring-expansion reactions of oxiranes with dimethylsulfxonium methylide were studied experimentally and modeled computationally at the density functional theory (DFT) and second-order Møller-Plesset (MP2) levels of theory utilizing a polarizable continuum model (PCM) to account for solvent effects. While the epoxide to oxetane ring expansion requires 13-17 kcal mol(-1) activation and occurs at elevated temperatures, the barriers for the ring expansions to oxolanes are higher (ca. 25 kcal mol(-1)) and require heating to 125 °C. Further expansions of these oxolanes to the six-membered oxanes are hampered by high barriers (ca. 40 kcal mol(-1)). We observe the complete conservation of the enantiomeric purities for the nucleophilic ring expansions of enantiomeric 2-mono- and 2,2-disubstituted epoxides and oxetanes with dimethylsulfoxonium methylide. This is a convenient general approach for the high-yielding preparation of optically active four- and five-membered cyclic ethers from oxiranes.


Subject(s)
Epoxy Compounds/chemistry , Sulfonium Compounds/chemistry , Molecular Conformation , Molecular Dynamics Simulation , Stereoisomerism , Thermodynamics
5.
Org Biomol Chem ; 7(7): 1397-403, 2009 Apr 07.
Article in English | MEDLINE | ID: mdl-19300825

ABSTRACT

Herein we shed light on the mechanism of the reaction of epoxides with ammonium thiocyanate to give the corresponding thiiranes in water, and we present a computational mechanistic model for this highly useful reaction.


Subject(s)
Ethylene Oxide/chemistry , Sulfides/chemical synthesis , Temperature , Water/chemistry , Catalysis , Computer Simulation , Crystallography, X-Ray , Models, Chemical , Models, Molecular , Molecular Structure , Stereoisomerism , Sulfides/chemistry , Thiocyanates/chemistry
6.
Org Lett ; 10(8): 1513-6, 2008 Apr 17.
Article in English | MEDLINE | ID: mdl-18366220

ABSTRACT

We present a mild and efficient method for the completely regioselective alcoholysis of styrene oxides utilizing a cooperative Brønsted acid-type organocatalytic system comprised of mandelic acid (1 mol %) and N,N'-bis-[3,5-bis-(trifluoromethyl)phenyl]-thiourea (1 mol %). Various styrene oxides are readily transformed into their corresponding beta-alkoxy alcohols in good to excellent yields at full conversion. Simple aliphatic and sterically demanding, as well as unsaturated and acid-sensitive alcohols can be employed.

7.
Chem Commun (Camb) ; (41): 4315-7, 2006 Nov 04.
Article in English | MEDLINE | ID: mdl-17047852

ABSTRACT

The effects of hydrogen-bonding organocatalysts and water for the acceleration of epoxide openings with a variety of nucleophiles are additive and lead to excellent yields of the catalyzed reactions in water.

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