The use of multi-element stable isotope analysis to monitor the origin of chondroitin sulfates

Continuous-flow isotope ratio mass spectrometry (CF-IRMS) of deuterium, carbon, nitrogen, oxygen and sulfur has been used to analyse samples of pure chondroitin sulfates from known animal sources (shark, squid, salmon, pig and bovine). There is a need to control the origin of this dietary supplement, which is extracted from several types of animals: for traditional, ethical, or economic reasons, a given source of natural products of animal origin can be preferred to another, and can therefore have a different price. Twenty-three samples collected in Europe and Asia were analysed by IRMS. The results, especially the isotopic deviations of sulphur, oxygen and deuterium, show a significant discrimination between marine and terrestrial origins of this compound which will provide a convenient and efficient way to control the declared sources in the market. The differences observed between origins are further discussed.     

Diels–Alder reactions of directly C3-dieneylated chlorophyll derivatives

The [4π?+?2π] cycloaddition of methyl 3-(1,3-butadien-1/2-yl)pyropheophorbides-a with tetracyanoethylene, dimethyl acetylenedicarboxylate, and naphthoquinone gave the corresponding Diels–Alder reaction adducts. The trans-1-substituted 1,3-butadiene was more reactive than its regioisomeric 2-substituent. The oxidation of some cycloadducts gave C3-arylated chlorophyll derivatives, whose ortho-substitution blue-shifted the corresponding Qy absorption maxima in dichloromethane because of the steric repulsion between the aryl and chlorin π-planes.     

Diffusion-weighted magnetic resonance imaging of human skeletal muscles: gender-, age- and muscle-related differences in apparent diffusion coefficient

Purpose

To evaluate the apparent diffusion coefficient (ADC) of skeletal muscle based on signal intensity (SI) attenuation vs. increasing b values and to determine ADC differences in skeletal muscles between genders, age groups and muscles.

Materials and Methods

Diffusion-weighted images (b values in the range of 0–750 s/mm² at increments of 50 s/mm²) of the ankle dorsiflexors (116 subjects) and the erector spinae muscles (86 subjects) were acquired with a 1.5-T MR device. From the two different slopes obtained in SI vs. b-value logarithmic plots, ADC^b0–50 (b values=0 and 50 s/mm²) reflected diffusion and perfusion, while ADC^b50–750 (b values in the range of 50–750 s/mm² at increments of 50 s/mm²) approximated the true diffusion coefficient. Moreover, to evaluate whether this b-value combination is appropriate for assessing the flow component within muscles, diffusion-weighted images of the ankle dorsiflexors (10 subjects) were obtained before and during temporal arterial occlusion.

Results

ADC^b0–50 and ADC^b50–750 were found to be 2.64×10^–3 and 1.44×10^–3 mm²/s in the ankle dorsiflexors, and 3.02×10^–3 and 1.49×10^–3 mm²/s in the erector spinae muscles, respectively. ADC^b0–50 was significantly higher than ADC^b50–750 in each muscle (P<.01). The erector spinae muscles showed significantly higher ADC values than the ankle dorsiflexors (P<.01). However, for each muscle, there were few significant gender- and age-related ADC differences. Following temporal occlusion, ADC^b0–50 of the ankle dorsiflexors decreased significantly from 2.49 to 1.6×10^–3 mm²/s (P<.01); however, ADC^b50–750 showed no significant change.

Conclusion

Based on the SI attenuation pattern, muscle ADC could be divided into ADC that reflects both diffusion and perfusion, and ADC that approximates a true diffusion coefficient. There were significant differences in ADC of functionally distinct muscles. However, we barely found any gender- or age-related ADC differences for each muscle.     

The fundamental groups of one-dimensional wild spaces and the Hawaiian earring

Let be a one-dimensional space which contains a copy of a circle and let it not be semi-locally simply connected at any point on Then the fundamental group of cannot be embeddable into a free -product of n-slender groups, for instance, the fundamental group of the Hawaiian earring. Consequently, any one of the fundamental groups of the Sierpinski gasket, the Sierpinski curve, and the Menger curve is not embeddable into the fundamental group of the Hawaiian earring.

     

On ℤ-kernel groups

Archiv der Mathematik -     

Formation and reactions of aryldiazomethane radical cations

Dicyanoanthracene-sensitized photolysis of aryldiazomethanes affords stilbenes with cis/trans ratios of ～3 via free radical cations; anodic oxidation gives similar results but via radical cations adsorbed on electrode surface.     

Coulometric Anodic Stripping Voltammetry of Lead at Copper Column Electrode

A flow coulometric electroanalytical system using a copper column electrode with a copper wire inserted into a Nafion tube was developed to determine Pb(II) content based on anodic stripping voltammetry. The electrolysis efficiency of 5 μM Pb(II) was evaluated to be 100.4±4.5 % (n=5) when the length of the copper wire and flow rate of the Pb(II) solution were 50 cm and 0.1 mL min⁻¹, respectively. The amount of electricity due to the re-oxidation of Pb electrodeposited at the copper column electrode was proportional to the concentration of Pb(II) in the range between 0.1 to 100 μM, and the limit of detection for Pb(II) was 0.8 μM for a deposition time of 15 min. Interference from the presence of Cd(II) could be avoided and the selective determination of Pb(II) was successfully achieved by adjustment of the electrodeposition potential.     

Sensitization of wide band gap photocatalysts to visible light by molten CuCl treatment

Cu(i)-substituted metal oxide photocatalysts were prepared using molten CuCl treatment of wide band gap photocatalysts. The Cu(i)-substituted metal oxide photocatalysts possessed a new absorption band in the visible light region and showed photocatalytic activity for hydrogen evolution from an aqueous solution containing sulfur sacrificial reagents under visible light irradiation. Notably, the Cu(i)–K₂La₂Ti₃O₁₀ and Cu(i)–NaTaO₃ photocatalysts showed relatively high activities for hydrogen evolution and gave apparent quantum yields of 0.18% at 420 nm. These photocatalysts responded up to 620 nm. Thus, Cu(i)-substitution using a molten CuCl treatment was an effective strategy for sensitizing a metal oxide photocatalyst with a wide band gap to visible light.