Catalytic synthesis of methyl 9,10‐dihydroxystearate from technical feedstocks in continuous flow via epoxidation and hydrolysis

The sequence of the homogeneously Ru-catalyzed epoxidation of methyl oleate and acid-catalyzed hydrolysis of the corresponding epoxide methyl 9,10-epoxy stearate is successfully transferred from batch into flow mode, allowing for the continuous production of methyl 9,10-dihydroxystearate. Thereby, methyl oleate is first converted up to 97% within 14 min at excellent selectivity in the epoxidation using aqueous hydrogen peroxide as the sole oxidant. In the subsequent hydrolysis, a residence time of 10 min is sufficient for quantitative conversion of the epoxide. The desired, pure vicinal diol is isolated upon crystallization from the crude reaction mixture in an integrated process starting from technical grade (91.5%) substrate. The isolated yield is increased upon the addition of water as a green antisolvent from 75% up to 97%. Finally, the concept is transferred to methyl oleate of even lower purity (76%), still obtaining an isolated yield of 66% of the vicinal diol. Thus, the integration of sequential epoxidation and hydrolysis into continuous flow and subsequent crystallization allows for high conversion and selectivities within a total residence time of 27 min, corresponding to a space–time yield of 190 g h−1 L−1 in the epoxidation and 164 g h−1 L−1 in the hydrolysis, respectively. Practical applications: The modular flow setup enables the targeted functionalization toward the epoxide intermediate or the vicinal diol. Both offer versatile applications for the production of polymers, surfactants, or toward further conversion as in oxidative cleavage starting from methyl oleate. The application of flow chemistry offers advantages for the safe handling of hydrogen peroxide even at high temperatures. With fats and oils being natural substances, oleochemicals such as fatty acid methyl esters are typically available in technical purity so that efficient strategies for the isolation of pure products are of need. Crystallization of the product is promising, as additional organic solvents are not required. Thus, using the difference in melting point and solubility behavior of the desired product compared to other compounds is a promising method for the applicability of renewable resource-based substrate mixtures

Diagnosis of tetrahydrobiopterin deficiency using filter paper blood spots: further development of the method and 5 years experience

In every newborn with even mild hyperphenylalaninemia (HPA) tetrahydrobiopterin (BH4) deficiencies need to be excluded as soon as possible. Differential diagnosis is most commonly performed by analysis of urinary neopterin and biopterin. In 2005 a new method for the measurement of neopterin, biopterin and other pterins in dried blood spot (DBS) on filter paper was introduced. In order to evaluate the usefulness of this method as a standard tool for differential diagnosis of HPAs we analyzed neopterin, biopterin, pterin and dihydropteridine reductase activity in DBS from 362 patients with HPA over the period of five years. Age-dependent reference values were established for the HPA population. Sixty-four patients with BH4 deficiency (27 patients with 6-pyruvoyl-tetrahydropterin synthase deficiency, seven with GTP cyclohydrolase I deficiency, and 30 with dihydropteridine reductase) were identified. Reference values for neopterin and biopterin in DBS were calculated for each of the variants. 6-pyruvoyl-tetrahydropterin synthase and GTP cyclohydrolase I deficiency can be diagnosed by neopterin and biopterin analysis alone, while for diagnosis of dihydropteridine reductase deficiency additional determination of enzyme activity from the same DBS is essential. Regarding test sensitivity, the interpretation of neopterin and biopterin concentration per hemoglobin is more valid than the interpretation of neopterin and biopterin per liter. Percentage of biopterin, of the sum of neopterin and biopterin should always be calculated. In addition, determination of hemoglobin concentration is essential as a measure for efficient extraction of neopterin and biopterin. Although the measurement of neopterin and biopterin in urine is more sensitive due to the higher concentrations present, our data prove the usefulness of their measurement from DBS for the routine diagnosis of BH4 deficiencie

Optimized immobilization of ZnO:Co electrocatalysts realizes 5% efficiency in photoassisted splitting of water

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Correction: There is an error in Fig. 8 of the manuscript. The correct Fig. 8 is shown in the additional file. To cite the Correction refer to DOI:10.1039/c6ta90030e.Organic solvents with varied electrophoretic mobility have been employed for deposition of nanocrystalline ZnO: Co particles onto fluorinated tin oxide supports. Evaluation of the electrochemical activity for the oxygen evolution reaction proves a clear solvent-dependence with highest activity upon deposition from acetonitrile and lowest activity upon deposition from ethanol. Analysis of the resulting layer thickness and density attributes the improved electrochemical activity of acetonitrile-prepared samples to larger film thicknesses with lower film densities, i.e. to films with higher porosity. The findings suggest that the ZnO: Co films represent an initially nanocrystalline system where the catalytic activity is predominantly confined to a thin surface region rather than to comprise the entire volume. Closer inspection of this surface region proves successive in operando transformation of the nanocrystalline to an amorphous phase during evolution of oxygen. Furthermore, less active but highly transparent ZnO: Co phases, prepared from ethanol-containing suspensions, can be successfully employed in a stacking configuration with a low-cost triple-junction solar cell. Thereby, a solar-to-hydrogen efficiency of 5.0% in splitting of water at pH 14 could be realized. In contrast, highly light-absorbing acetonitrile/acetone-prepared samples limit the efficiency to about 1%, demonstrating thus the decisive influence of the used organic solvent upon electrophoretic deposition. Stability investigations over several days finally prove that the modular architecture, applied here, represents an attractive approach for coupling of highly active electrocatalysts with efficient photovoltaic devices.BMBF, 03IS2071F, Light2Hydrogen - Energien für die ZukunftDFG, SPP 1613, Regenerativ erzeugte Brennstoffe durch lichtgetriebene Wasserspaltung: Aufklärung der Elementarprozesse und Umsetzungsperspektiven auf technologische Konzept

Long‐term Cardiovascular Risks Associated With an Elevated Heart Rate: The Framingham Heart Study

Background: Higher heart rate has been associated with an adverse prognosis, but most prior studies focused on individuals with known cardiovascular disease or examined a limited number of outcomes. We sought to examine the association of baseline heart rate with both fatal and nonfatal outcomes during 2 decades of follow‐up. Methods and Results: Our study included 4058 Framingham Heart Study participants (mean age 55 years, 56% women). Cox models were performed with multivariable adjustment for clinical risk factors and physical activity. A total of 708 participants developed incident cardiovascular disease (303 heart failure, 343 coronary heart disease, and 216 stroke events), 48 received a permanent pacemaker, and 1186 died. Baseline heart rate was associated with incident cardiovascular disease (hazard ratio [HR] 1.15 per 1 SD [11 bpm] increase in heart rate, 95% CI 1.07 to 1.24, P=0.0002), particularly heart failure (HR 1.32, 95% CI 1.18 to 1.48, P<0.0001). Higher heart rate was also associated with higher all‐cause (HR 1.17, 95% CI 1.11 to 1.24, P<0.0001) and cardiovascular mortality (HR 1.18, 95% CI 1.04 to 1.33, P=0.01). Spline analyses did not suggest a lower threshold beyond which the benefit of a lower heart rate abated or increased. In contrast, individuals with a higher heart rate had a lower risk of requiring permanent pacemaker placement (HR 0.55, 95% CI 0.38 to 0.79, P=0.001). Conclusions: Individuals with a higher heart rate are at elevated long‐term risk for cardiovascular events, in particular, heart failure, and all‐cause death. On the other hand, a higher heart rate is associated with a lower risk of future permanent pacemaker implantation

Sustained Water Oxidation by Direct Electrosynthesis of Ultrathin Organic Protection Films on Silicon

Artificial photosynthesis allows exceeding the efficiency and stability limits of natural photosynthesis. Based on the use of semiconducting absorbers, high efficiency in water photolysis has been achieved in various photoelectrode configurations. However, integrated systems are limited in their stability, and more stable half-cell electrodes use protection films prepared by laborious methods. Herein, the facile low-temperature preparation of ultrathin organic protection coatings is demonstrated. The formation is based on the catalytic properties of water oxidation catalysts toward alcohol-polymerization reactions, which results in the formation of hitherto unknown protection layers on silicon. The interfacial layers are generated via iodine-mediated electro-reductive polymerization of ethanol, concomitantly forming during electrophoretic transport of RuO_2 onto silicon supports. Reaction chemistry analyses show that the RuO_2-induced catalysis introduces E2-elimination reactions which result in a carbon sp^3 –sp^2 transformation of the film. For the two modes of photoelectrochemical operation, the photovoltaic and the photoelectrocatalytic mode, 20 and 15 mA cm^(−2) photocurrent densities, respectively, are obtained with unaltered output for 8 and 24 h. The interfacial layer enables Si photovoltages of 500 mV, demonstrating extraordinary electronic interface quality. Since only hydrogen termination of the surface is a prerequisite for growth of the organic protection layer, the method is applicable to a wide range of semiconductors

Metabolite Profiles During Oral Glucose Challenge

To identify distinct biological pathways of glucose metabolism, we conducted a systematic evaluation of biochemical changes after an oral glucose tolerance test (OGTT) in a community-based population. Metabolic profiling was performed on 377 nondiabetic Framingham Offspring cohort participants (mean age 57 years, 42% women, BMI 30 kg/m2) before and after OGTT. Changes in metabolite levels were evaluated with paired Student t tests, cluster-based analyses, and multivariable linear regression to examine differences associated with insulin resistance. Of 110 metabolites tested, 91 significantly changed with OGTT (P ≤ 0.0005 for all). Amino acids, β-hydroxybutyrate, and tricarboxylic acid cycle intermediates decreased after OGTT, and glycolysis products increased, consistent with physiological insulin actions. Other pathways affected by OGTT included decreases in serotonin derivatives, urea cycle metabolites, and B vitamins. We also observed an increase in conjugated, and a decrease in unconjugated, bile acids. Changes in β-hydroxybutyrate, isoleucine, lactate, and pyridoxate were blunted in those with insulin resistance. Our findings demonstrate changes in 91 metabolites representing distinct biological pathways that are perturbed in response to an OGTT. We also identify metabolite responses that distinguish individuals with and without insulin resistance. These findings suggest that unique metabolic phenotypes can be unmasked by OGTT in the prediabetic state

Recent advances on time-stretch dispersive Fourier transform and its applications

The need to measure high repetition rate ultrafast processes cuts across multiple areas of science. The last decade has seen tremendous advances in the development and application of new techniques in this field, as well as many breakthrough achievements analyzing non-repetitive optical phenomena. Several approaches now provide convenient access to single-shot optical waveform characterization, including the dispersive Fourier transform (DFT) and time-lens techniques, which yield real-time ultrafast characterization in the spectral and temporal domains, respectively. These complementary approaches have already proven to be highly successful to gain insight into numerous optical phenomena including the emergence of extreme events and characterizing the complexity of laser evolution dynamics. However, beyond the study of these fundamental processes, real-time measurements have also been driven by particular applications ranging from spectroscopy to velocimetry, while shedding new light in areas spanning ultrafast imaging, metrology or even quantum science. Here, we review a number of landmark results obtained using DFT-based technologies, including several recent advances and key selected applications. © 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group