Biomechanical characteristics of self-expanding sinus stents during crimping and deployment_A comparison between different biomaterials.

Self-expanding sinus stents are often used in functional endoscopic sinus surgery to treat inflamed sinuses. The PROPEL self-expanding sinus stent offers mechanical support to the sinus cavity to prevent restenosis. The stent is made of a bioabsorbable material (PLGA) that disappears after wound healing. However, complications such as foreign body sensation and severe stent migration/expulsion have been reported after implantation. Little is known about the contact characteristics of self-expanding sinus stents from when the stent is crimped into the insertion device through to deployment into the sinus cavity. This current study developed a test platform to analyze the biomechanical behavior of the stent during this process. Three common bioabsorbable materials, PLGA, PCL and Mg alloy, were evaluated to understand how the choice of material affects the biomechanical characteristics of self-expanding sinus stents. The results showed that the material can have a considerable influence on the contact characteristics during crimping and deployment. When crimped, the PLGA and Mg alloy stents showed much higher plastic strain and contact stress than the PCL stent. When deployed, the PCL stent had the largest contact area (4.3 mm2) and the lowest contact pressure (0.1 MPa) on the inner surface of the sinus canal. The results indicate that PCL could be a suitable choice for self-expanding sinus stents. This current study provides a method for observing the biomechanical characteristics of sinus stents during stent crimping and deployment.

Model-based correction of finite aperture effect in photoacoustic tomography.

In this study, we adopt a model-based correction method to reduce the finite aperture effect in photoacoustic tomography (PAT)--the tangential resolution deteriorates as the imaging point moves away from the circular scanning center. Such degradation in resolution originates from the spatial impulse responses (SIRs) of the used finite-sized unfocused transducer. Based on a linear, discrete PAT imaging model, the proposed method employs a spatiotemporal optimal filter designed in minimum mean square error sense to compensate the SIRs associated with an unfocused transducer at every imaging point; thus retrospective restoration of the tangential resolution can be achieved. Simulation and experimental results demonstrate that this method can substantially improve the degraded tangential resolution for PAT with finite-sized unfocused transducers while retaining the radial resolution.

Assessment of the clinical efficacy of the heart spectrum blood pressure monitor for diagnosis of atrial fibrillation: An unblinded clinical trial.

Atrial fibrillation (AF) is the most common arrhythmia. The most common diagnostic method, 12-lead electrocardiogram (ECG), can record episodes of arrhythmia from which the type and severity can be determined. The Heart Spectrum Blood Pressure Monitor (P2; OSTAR Meditech Corp., New Taipei City, Taiwan) is used to measure cardiovascular pressure change with fast Fourier transform (FFT) analysis to obtain heart rate frequency variability and accurate blood pressure data. We compared the diagnostic efficacy of the Heart Spectrum Blood Pressure Monitor to a 12-lead ECG (gold standard) for patients with AF. Three measurement methods were used in this study to analyze the heart index and compare the results with simultaneous 12-lead ECG: blood pressure; mean arterial pressure, which was calculated from individual blood pressure as a constant pressure; and a constant pressure of 60 mmHg. The physician used a 12-lead ECG and the Heart Spectrum Blood Pressure Monitor simultaneously. The Heart Spectrum Blood Pressure Monitor used FFT analysis to diagnose AF, and the findings were compared to the 12-lead ECG readings. This unblinded clinical trial was conducted in the emergency department of Taipei Medical University Hospital. Twenty-nine subjects with AF and 33 without AF aged 25 to 97 y (mean, 63.5 y) were included. Subjects who were exposed to high-frequency surgical equipment during testing, those with cardiac pacemakers or implantable defibrillators, and pregnant women were excluded. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 97%, 97%, 97%, and 97%, respectively, for method 1; 90%, 100%, 100%, and 91%, respectively, for method 2; and 100%, 94%, 94%, and 100%, respectively, for method 3. The sensitivity, specificity, PPV, and NPV for both methods ranged between 90% and 100%, indicating that the Heart Spectrum Blood Pressure Monitor can be effectively applied for AF detection.

2,7-Bis(1H-pyrrol-2-yl)ethynyl-1,8-naphthyridine: an ultrasensitive fluorescent probe for glucopyranoside.

[structure: see text] A push-pull conjugated molecule, 2,7-bis(1H-pyrrol-2-yl)ethynyl-1,8-naphthyridine (BPN), has been designed to bind selectively with octyl glucopyranoside (OGU). The BPN/OGU quadruple hydrogen-bonding complex adopts a rigid BPN conformation in which the proton donor (d) and acceptor (a) relays (daad) are resonantly conjugated through the ethynyl bridge, inducing pi-electron delocalization, i.e., a charge transfer effect. The excellent photophysical properties make BPN a highly sensitive probe for monitoring glucopyranoside to a detection limit of approximately 100 pM.

Syntheses and remarkable photophysical properties of 5-(2-pyridyl) pyrazolate boron complexes; photoinduced electron transfer.

A new series of pyridyl pyrazolate boron complexes 2a-e have been synthesized, in which 2a-c exhibit remarkable dual fluorescence properties due to the photoinduced electron transfer reaction.

Excited-state intramolecular proton transfer in five-membered hydrogen-bonding systems: 2-pyridyl pyrazoles.

The excited-state intramolecular proton transfer (ESIPT) reaction in five-membered N-H...N hydrogen-bonding systems has been explored through design and syntheses of a series of 5-(2-pyridyl) 1-H-pyrazoles 1a-d. The ESIPT mechanism was confirmed through spectroscopy, relaxation dynamics, and corresponding methylated analogues. The results demonstrate for the first time a unique system among ESIPT molecules, in which ESIPT incorporates an appreciably large energy barrier fine-tuned by the skeletal reorganization. This makes 1a-d systems ideal models for probing the reaction potential energy surface.

Multiple hydrogen bonds tuning guest/host excited-state proton transfer reaction: its application in molecular recognition.

A molecular recognition concept exploiting multiple-hydrogen-bond fine-tuned excited-state proton-transfer (ESPT) was conveyed using 3,4,5,6-tetrahydrobis(pyrido[3,2-g]indolo)[2,3-a:3',2'-j]acridine (1a). The catalytic type 1a/carboxylic acids hydrogen-bonding (HB) complexes undergo ultrafast ESPT, resulting in an anomalously large Stokes shifted tautomer emission (lambdamax approximately 600 nm). Albeit forming a quadruple HB complex, ESPT is prohibited in the noncatalytic-type 1a/urea complexes (lambdamax approximately 430 nm). The HB configuration tuning ESPT properties lead to a feasible design for sensing multiple-HB-site analytes of biological interest.