Addition of arylboronic acids to arylpropargyl alcohols en route to indenes and quinolines

A regio- and stereoselective rhodium-catalyzed synthesis of trisubstituted allylic alcohols is described. The utility of these synthons is demonstrated in a convenient synthesis of indenes and quinolines.     

Monte Carlo simulation of near infrared autofluorescence measurements of in vivo skin

The autofluorescence properties of normal human skin in the near-infrared (NIR) spectral range were studied using Monte Carlo simulation. The light-tissue interactions including scattering, absorption and anisotropy propagation of the regenerated autofluorescence photons in the skin tissue were taken into account in the theoretical modeling. Skin was represented as a turbid seven-layered medium. To facilitate the simulation, ex vivo NIR autofluorescence spectra and images from different skin layers were measured from frozen skin vertical sections to define the intrinsic fluorescence properties. Monte Carlo simulation was then used to study how the intrinsic fluorescence spectra were distorted by the tissue reabsorption and scattering during in vivo measurements. We found that the reconstructed model skin spectra were in good agreement with the measured in vivo skin spectra from the same anatomical site as the ex vivo tissue sections, demonstrating the usefulness of this modeling. We also found that difference exists over the melanin fluorescent wavelength range (880-910 nm) between the simulated spectrum and the measured in vivo skin spectrum from a different anatomical site. This difference suggests that melanin contents may affect in vivo skin autofluorescence properties, which deserves further investigation.     

Computing quasiconformal maps using an auxiliary metric and discrete curvature flow

Surface mapping plays an important role in geometric processing, which induces both area and angular distortions. If the angular distortion is bounded, the mapping is called a quasiconformal mapping (QC-Mapping). Many surface mappings in our physical world are quasiconformal. The angular distortion of a QC mapping can be represented by the Beltrami differentials. According to QC Teichmüller theory, there is a one-to-one correspondence between the set of Beltrami differentials and the set of QC surface mappings under normalization conditions. Therefore, every QC surface mapping can be fully determined by the Beltrami differential and reconstructed by solving the so-called Beltrami equation. In this work, we propose an effective method to solve the Beltrami equation on general Riemann surfaces. The solution is a QC mapping associated with the prescribed Beltrami differential. The main strategy is to define an auxiliary metric (AM) on the domain surface, such that the original QC mapping becomes conformal under the auxiliary metric. The desired QC-mapping can then be obtained by using the conventional conformal mapping method. In this paper, we first formulate a discrete analogue of QC mappings on triangular meshes. Then, we propose an algorithm to compute discrete QC mappings using the discrete Yamabe flow method. To the best of our knowledge, it is the first work to compute the discrete QC mappings for general Riemann surfaces, especially with different topologies. Numerically, the discrete QC mapping converges to the continuous solution as the mesh grid size approaches to 0. We tested our algorithm on surfaces scanned from real life with different topologies. Experimental results demonstrate the generality and accuracy of our auxiliary metric method.     

Brain networks responsive to aversive visual stimuli in humans

The neural mechanisms subserving recognition of noxious stimuli and empathy for pain appear to involve at least in part the cortical regions associated with the processing of pain affect. An important issue concerns the specificity of brain networks associated with observing and representing painful conditions, in comparison with other unpleasant stimuli. Recently, we found both similarities and differences between the brain patterns of activity related to the observation of noxious or disgusting stimuli delivered to one hand or foot. Overlap regions included the perigenual anterior cingulate (pACC), whose activity was related to the perceived unpleasantness. We aimed here at revealing how pACC functional connectivity changes in relationship to the different experimental conditions, using a psychophysiological interaction model. Activity in pACC during the observation of painful stimuli was specifically and positively related to regions in the right hemisphere, including portions of the prefrontal, midcingulate and insular cortex. On the other hand, positive changes in pACC connectivity during the vision of disgusting stimuli were present in the right basal ganglia. These data suggest that pACC activity is part of different networks involved in the recognition of painful or disgusting stimuli.     

Particulate matter (PM10) from São Carlos-SP (Brazil): spectroanalytical techniques to evaluate and determine chemical elements

Chemical composition of PM10 was studied during the period of 2014–2015 in the city of São Carlos, Brazil (‘Dos Voluntários’ Square). PM10 samples were directly analysed by wavelength dispersive X-ray fluorescence – WD-XRF (Al, Ca, Ce, Cl, Fe, K, Mg, P, S, Si, Ti, V, and Zn), and by laser-induced breakdown spectroscopy – LIBS (Ba, Ca, Fe, K, Mg, Na, Si and Ti) both for qualitative purposes. For quantitative analysis of Al, Ba, Ca, Fe, K, Na, S, and Zn, the analytes were extracted from samples of PM10 collected, in filters of glass fibre, with an extractive acid solution (HNO₃ and HCl) and determined by inductively coupled plasma optical emission spectrometry – ICP OES. Spatial variations of elemental concentrations (ng m^–3) were significantly higher in winter Al (19.0), Ba (13.6), Ca (20.0), Na (27.0), S (37.1), and Zn (9.5), autumn showed the highest concentration of Na (26.4), spring showed the highest concentration of Fe (11.6), K (13.1) and also S (25.3) and summer did not show a high concentration in the comparison between the seasons at the site. Using principal component analysis (PCA), as a data interpretation tool, with the data obtained by the WD-XRF and LIBS it was not possible to obtain a good correlation, but with the data of ICP OES, it was possible to verify correlations between identified and determinate elements, with samples collected in the autumn, winter, spring and summer seasons in the city of São Carlos. These associated analytical techniques were excellent tools in environmental monitoring, through the analysis of PM10 samples, presenting reliable and efficiency strategy, and based on the PCA and the EF equation was possible to draw the profile of the possible origins of these elements in the city.     

The aerobic methylation of arsenic by microorganisms in the presence of l-methionine-methyl-d3

The microorganisms Scopulariopsis brevicaulis, Candida humicola, and Gliocladium roseum growing aerobically, methylate a range of arsenic compounds to produce R′R″As(CH₃) (R′  R″  CH₃; R′  n-C₄H₉, R″  CH₃). When l-methionine-methyl-d₃ is added to the cultures the CD₃ label is incorporated, intact, in the evolved arsine to a considerable extent, indicating that S-adenosylmethionine or some related sulphonium compound is involved in the biological process.     

尿素刀豆生物传感器的研制

本文报告了尿素刀豆生物传感器的制备和性能。斜率46.0—49.7mv.dec~(-1)、线性范围2×10~(-4)—5×10~(-3)mol.L~(-1),检测下限2.5×10~(-5)mol.L~(-1)。该传感器用于血液中尿氮含量的测定,此测定结果与分光光度法测定结果无明显差异。     

对甲苯磺酸催化合成乳酸异戊酯

报道了对甲苯磺酸在异戊醇和乳酸酯化反应中的应用 ,讨论了合成条件。实验表明其催化活性良好。     

A qualitative test for detection of ferroelectricity in crystalline powder

By use of the pyroelectric temperature analysis (PTA) of the unsintered pressed powder samples in the temperature region of the phase transition it is possible to determine the value of the electric charge released during the transition. The comparison of results of the transition charges obtained from unpoled as well as from poled samples can differentiate a ferroelectric from nonferroelectric material. The proposed method is successfully validated with KH₂PO₄, (NH₄)₂SO₄ and NH₄H₂PO₄ pressed powder.