Capacities Associated with Calderón-Zygmund Kernels

Analytic capacity is associated with the Cauchy kernel 1/z and the L ^∞-norm. For n?∈??, one has likewise capacities related to the kernels $K_i(x)=x_i^{2n-1}/|x|^{2n}$ , 1?≤?i?≤?2, $x=(x_1,x_2)\in{\mathbb R}^2$ . The main result of this paper states that the capacities associated with the vectorial kernel (K ₁, K ₂) are comparable to analytic capacity.     

On the noise limit of stress and temperature measurements with micro‐Raman spectroscopy

We report for the first time on the thorough experimental and theoretical assessment of the noise limit of mechanical stress and temperature measurements with micro‐Raman spectroscopy. A comprehensive study has been performed in which, for different incident laser light intensities and acquisition times, 1000 Raman spectra of mono‐crystalline silicon were acquired per setting. Curve fitting was employed to obtain the peak positions of all the spectra, from which the standard deviations of the measured peak positions were obtained versus the total accumulated amount of laser light incident on the sample during one measurement. It has been found that the noise in the obtained peak position decreases as 1/sqrt(n) over more than three decades of the incident amount of laser light. At very low light conditions, the noise decreases as 1/n. By comparing the experimental results obtained to recent theoretical work, we show that the acquisition is limited by photon shot noise over most of the range and is limited by electronic detector noise at very low light conditions only. Pixelation errors do not play a role. It is concluded that the low electronic noise of typical Raman spectroscope detectors is overkill for the investigation of mechanical stress and temperature in silicon and other materials with comparable peaks, as it has absolutely no influence on the noise level of such an experiment. Maximum Raman signal intensity on the detector and high quantum efficiency detection are more important. Copyright © 2013 John Wiley & Sons, Ltd.     

Magnetic resonance imaging in hemophilic children: value of gradient echo and contrast-enhanced imaging

The purpose of this study was to determine the value of Gradient Echo imaging for the evaluation of cartilage (3D fatsat) and blood products (2D Hemoflash), and the use of contrast enhanced SE imaging for the evaluation of synovial changes, in comparison to the clinical evaluation of children with hemophilia A. We investigated 21 joints in 16 patients with evidence of hemophilia A (mean age 11.3+/-2.1 years). In all patients, clinical examination, plain film radiographs, and MR evaluation were performed magnetic resonance imaging (MRI) was performed by using sagittal T1 SE and T2 SE images, as well as 3D fatsat GE and 2D GE images. Axial and sagittal T1 weighted SE images were obtained before and after contrast application. Findings from the clinical examination and MR imaging, regarding the evaluation of blood, synovia, and cartilage were compared. Clinical examination revealed evidence of a bleeding episode in 12 joints (57.1%), whereas MRI revealed evidence of blood or blood products in 15 joints (71.4%). Clinical investigations, including bleeding scores, pain scores, and physical examination scores did not correlate with MR findings. Due to the MR findings in 6 of 16 patients, therapeutic management was changed from on demand to prophylactic therapy. MR imaging with gradient echo and contrast-enhanced sequences is more sensitive than clinical examination for the detection of blood products in children with hemophilia. Its ability to demonstrate potentially early stages of cartilage or synovial alterations might assist in therapy planning. Clinical scores might underestimate effects of hemophilia.     

MRI visualization of proteoglycan depletion in articular cartilage via intravenous administration of Gd-DTPA

The effect of intravenous administration of gadolinium diethylenetriamine-pentaacetic acid (Gd-DTPA) on MR images was studied in vitro, using pathologic osteochondral specimens removed during surgery for total endoprosthesis, and in vivo, on a group of volunteers. In ex vivo specimens, lesions of different shape having lower T1 were detected which corresponded to areas with depleted proteoglycans found histologically. In vivo experiments on young volunteers showed that the time course of cartilage enhancement was different for different anatomies. The time for maximum enhancement ranged from 45 min for the ventral femoral condyle to 270 min for patellar cartilage.     

Magnetic resonance arthrography (MRA) in the postoperative shoulder.

To evaluate changes in capsular mechanisms and the labroligamentous complex with magnetic resonance arthrography (MRA) after shoulder surgery and to establish possible criteria for the expected post-operative appearance of the shoulder. MRA of the shoulder was performed in 16 patients, before and 6 months after undergoing arthroscopic surgery for recurrent unidirectional dislocation. MR studies were performed after application of a constant amount of contrast solution (2 mmol Gd-DTPA). Axial and coronal oblique T1-weighted images were obtained with and without fat suppression techniques. Anterior (a) and posterior (p) capsular distances were measured, and the p/a ratio was established. Capsule thickness, capsular leaking, estimation of the volume of the axillary recess, appearance of the glenohumeral ligaments, and evidence of labral lesions were compared on pre- and postoperative images. Mean anterior capsular distance (a) decreased from 9.73 +/- 1.03 mm preoperatively to 5.27 +/- 2.49 mm postoperatively, whereas dorsal capsular distance (p) increased from 6.13 +/- 2.36 to 8.93 +/- 2.37. The p/a ratio increased from 0.64 +/- 0.25 to 2.36 +/- 2.54 (p = 0.007). Capsular leaking was suspected preoperatively in seven patients, but was not evident postoperatively. Capsular thickness and the estimated volume in the axillary recess did not change significantly. Contrast extension into pre-existent labral tears (nine patients) decreased or were not evident postoperatively. Changes in the appearance of the glenohumeral ligaments were found in six patients. Changes in capsular distances might be indicative of a decreased capsular laxity and could be a valuable criterion in the evaluation of the postoperative shoulder. Postoperative follow-up of labral tears is demonstrated by a decrease in contrast extension into or under a tear. Reactive capsular thickening or scar tissue formation can be reactive or preexistent. Changes in ligaments might be secondary to surgery. MRA may be helpful in the reevaluation of patients with suspected recurrent instability.     

Crossing VIMP and EIS for studying heterogeneous sets of copper/bronze coins

Journal of Solid State Electrochemistry - Electrochemical impedance spectroscopy (EIS) and voltammetry of immobilized particles (VIMP) measurements using air-saturated mineral water and...     

AlIII‐Catalysed Formation of Poly(limonene)carbonate: DFT Analysis of the Origin of Stereoregularity

Amino‐triphenolate derived Al^III complexes combined with suitable nucleophiles have been investigated as binary catalysts for the coupling of limonene oxide and carbon dioxide to afford alternating polycarbonates. These catalysts are able to produce stereoregular, perfectly alternating trans‐polymers from cis‐limonene oxide, whereas the pure trans isomer and cis/trans mixture give rise to lower degrees of stereoregularity. The best Al^III catalyst shows the potential to mediate the conversion of both stereoisomers of limonene oxide with high conversion levels of up to 71 % under neat conditions, indicating the high degree of robustness and atom‐efficiency of this catalytic process. Computational studies have revealed unique features of the binary catalyst system, among which is the preferred nucleophilic attack on the quaternary carbon centre in the limonene oxide substrate.     

Cetyl‐alcohol‐reinforced hollow fiber solid/liquid‐phase microextraction and HPLC–DAD analysis of ezetimibe and simvastatin in human plasma and urine

A new cetyl‐alcohol‐reinforced hollow fiber solid/liquid‐phase microextraction (CA–HF–SLPME) followed by high‐performance liquid chromatography–diode array detection (HPLC–DAD) method was developed for simultaneous determination of ezetimibe and simvastatin in human plasma and urine samples. To prepare the CA–HF–SLPME device, the cetyl‐alcohol was immobilized into the pores of a 2.5 cm hollow fiber micro‐tube and the lumen of the micro‐tube was filled with 1‐octanol with the two ends sealed. Afterwards, the prepared device was introduced into 10 mL of the sample solution containing the analytes with agitation. Under optimized conditions, calibration curves plotted in spiked plasma and urine samples were linear in the ranges of 0.363–25/0.49–25 μg L^?1 for ezetimibe/simvastatin and 0.193–25/0.312–25 μg L^?1 for ezetimibe/simvastatin in plasma and urine samples, respectively. The limit of detection was 0.109/0.174 μg L^?1 for ezetimibe/simvastatin in plasma and 0.058/0.093 μg L^?1 for ezetimibe/simvastatin in urine. As a potential application, the proposed method was applied to determine the concentration of selected analytes in patient plasma and urine samples after medication and satisfactory results were achieved. In comparison with reference methods, the CA–HF–SLPME–HPLC–DAD method demonstrates considerable potential in the biopharmaceutical analysis of selected drugs.     

Substituted imidazolium phenylphosphonate salts for nonlinear optical applications

Three candidates for potential applications as new nonlinear optical materials were investigated using x-ray crystallography to probe the structure and powder second harmonic generation to elicidate the nonlinear response of the materials. Three structures are reported: 1-benzylimidazolium phenylphosphonate, 2-ethylimidazolium phenylphosphonate, and 2-methylimidazolium phenylphosphonate. Of these three salts two, 2-ethylimidazolium phenylphosphonate and 2-methylimidazolium phenylphosphonate, are noncentrosymmetric and therefore display a nonlinear optical response.