The increasing global emergence of multidrug resistant (MDR) pathogens is categorized as one of the most important health problems. Therefore, the discovery of novel antimicrobials is of the utmost ...importance. Lichens provide a rich source of natural products including unique polyketides and polyphenols. Many of them display pharmaceutical benefits. The aim of this study was directed towards the characterization of sunflower oil extracts from the fruticose lichen, Usnea barbata. The concentration of the major polyketide, usnic acid, was 1.6 mg/mL extract as determined by NMR analysis of the crude mixture corresponding to 80 mg per g of the dried lichen. The total phenolics and flavonoids were determined by photometric assays as 4.4 mg/mL (gallic acid equivalent) and 0.27 mg/mL (rutin equivalent) corresponding to 220 mg/g and 13.7 mg/g lichen, respectively. Gram-positive (e.g., Enterococcus faecalis) and Gram-negative bacteria, as well as clinical isolates of infected chickens were sensitive against these extracts as determined by agar diffusion tests. Most of these activities increased in the presence of zinc salts. The data suggest the potential usage of U. barbata extracts as natural additives and mild antibiotics in animal husbandry, especially against enterococcosis in poultry.
Chemistry in Microstructured Reactors Jähnisch, Klaus; Hessel, Volker; Löwe, Holger ...
Angewandte Chemie (International ed.),
January 16, 2004, Letnik:
43, Številka:
4
Journal Article
Recenzirano
The application of microstructured reactors in the chemical process industry has gained significant importance in recent years. Companies that offer not only microstructured reactors, but also entire ...chemical process plants and services relating to them, are already in existence. In addition, many institutes and universities are active within this field, and process‐engineering‐oriented reviews and a specialized book are available. Microstructured systems can be applied with particular success in the investigation of highly exothermic and fast reactions. Often the presence of temperature‐induced side reactions can be significantly reduced through isothermal operations. Although microstructured reaction techniques have been shown to optimize many synthetic procedures, they have not yet received the attention they deserve in organic chemistry. For this reason, this Review aims to address this by providing an overview of the chemistry in microstructured reactors, grouped into liquid‐phase, gas‐phase, and gas–liquid reactions.
Good things come in small packages: The reduced dimensions of microstructured reactors offer many advantages in chemistry, particularly with respect to enhanced conversion, selectivity, and safety. This Review presents a discussion of the process parameters and the design of such reactors, which are crucial to their development and optimization.
Heterogeneous gas phase catalyst screening with catalysts applied on titer-plates is presented. It will be shown that titer-plates can as well be used for the sample preparation outside the reactor
...and for the catalyst testing in the reactor. For the catalyst preparation, the known wash-coating-impregnation procedure is applied. An alumina coated precursor is introduced into a manifold which utilizes the flow features of the separated wells for the impregnation of the precursor with solutions of the salts of a collection of transition metals. The impregnation liquid is flowing through the wells thus impregnating the surface of the porous γ-alumina layers within the microchannels. Less porous coatings are realized by the simultaneous gradient sputtering process developed on the basis of the standard sputtering process.
Some details about the reactor development and characterization as well as problems which arose are reported. For the description of the reactor performance, a number of coated titer-plates were tested and these results are presented. After this so-called primary screening, a second evaluation phase normally follows. In this second phase, the kinetic properties of a single catalyst shall be studied. For this purpose, a model which describes the fluidic behavior of the reacting gas in microchannels was developed. Applying the model will give further insights into the underlying reaction kinetic of a single selected catalyst in the so-called secondary screening phase.
Microstructured reactors such as the SuperFocus Interdigital micromixer offer an alternative to conventional large‐scale techniques. Flow patterns with reduced layer thicknesses lead to enlarged ...reactive surfaces that result in short mixing times, and thus high‐throughput reactions can be achieved. In their review on page 406 ff. K. Jähnisch, V. Hessel, et al. examine the potential of this new and powerful technology.
The prevalence of somatoform pain complaints was assessed in a representative sample of 2050 persons in Germany in the age range from 18 to 92 years by the Screening for Somatoform Symptoms ...questionnaire 57. A high percentage of the study participants turned out to complain of serious somatoform pains. Most frequently, back pain (30.5%), joint pain, pain in the arms and/or legs (19.9%) and headache or facial pain (19.5%) were reported. Women complained of more somatoform pain symptoms than men. Pain was higher with an increasing age, lower education, lower income, rural residency, and residency in Eastern Germany. While the prevalence of somatoform pain is high, the majority of patients does not receive adequate psychotherapeutic care but is inadequately treated by somatic treatments.
Langerhans cells (LC) of the skin represent bone marrow-derived dendritic antigen-presenting cells and are therefore important in pathophysiological processes such as rejection, graft-versus-host ...disease, and graft-versus-leukemia-reaction after bone marrow transplantation (BMT). For understanding of these diseases, the evaluation of the chimeric status of LC following BMT is of great interest. To analyze the sex chromosome constitution of LC in the skin, we established a modified and refined technique of combined immunophenotyping and fluorescence in situ hybridization (FISH) and investigated frozen sections of skin biopsies from nine patients after allogeneic sex-mismatched BMT and of two healthy donors for control. LC were specifically labeled using a fluorescent CD1 a antibody and hybridized simultaneously with X and Y chromosome-specific DNA probes. The results of this practical application on nine leukemia patients show the appearance of donor-type LC and the persistence of host-type LC at various times (36 up to 1395 days) after sex-mismatched BMT. Complete chimerism of LC could not be detected in any case. The frequency of recipient-specific LC ranged from 7% to 92% and showed no correlation with time postgrafting. We conclude from our results of 1461 analyzed LC that combined immunophenotyping and interphase cytogenetic analysis by FISH is the method of choice for the assessment of chimerism in a particular cell type after sex-mismatched BMT. Its practical application on other tissues affected by BMT-related pathophysiological processes reveals further knowledge of the time-dependent course of chimeric patterns after BMT.
Abstract
Mikrostrukturreaktoren haben in den letzten Jahren in der chemischen Verfahrenstechnik deutlich an Bedeutung gewonnen: Erste Firmen, die Prozessanlagen mit Mikrostrukturreaktoren anbieten, ...sind am Markt, eine Reihe von Instituten erforscht dieses Gebiet, Universitäten bieten Lehrveranstaltungen an, und einige verfahrenstechnisch orientierte Übersichtsartikel liegen bereits vor. Mikrostrukturierte Systeme sind besonders wertvoll für die Untersuchung stark exothermer schneller Reaktionen. Durch isotherme Betriebsweise lassen sich viele thermisch induzierte Nebenreaktionen zurückdrängen, was sicherheitstechnische Vorteile bei Reaktionen mit gefährlichen Reaktanten bringt. Obwohl viele organische Synthesen mit besseren Ergebnissen als in konventionellen Reaktoren durchgeführt wurden, ist der Mikrostrukturreaktor‐Technologie der große Durchbruch in der präparativen Chemie noch nicht gelungen. Aus diesem Grund unterstreicht dieser Aufsatz die Vorteile von Mikrostrukturreaktoren bei Flüssigphasen‐, Gasphasen‐ und Gas‐Flüssigphasen‐Reaktionen.
Mikrostrukturreaktoren
wie der abgebildete SuperFocus‐Interdigital‐Mikromischer bieten eine Alternative zu konventionellen großtechnischen Prozessen. Strömungsmuster mit minimalen Schichtdicken ...führen zur Vergrößerung der Grenzflächen. So werden sehr kurze Mischzeiten erzielt, die hohe Durchsätze in den winzigen Reaktoren ermöglichen. K. Jähnisch, V. Hessel et al. vermitteln in ihrem Aufsatz auf S. 410 ff. das eindrucksvolle Potenzial dieses jungen Forschungsgebiets.
Mikrostrukturreaktoren wie der abgebildete SuperFocus‐Interdigital‐Mikromischer bieten eine Alternative zu konventionellen großtechnischen Prozessen. Strömungsmuster mit minimalen Schichtdicken ...führen zur Vergrößerung der Grenzflächen. So werden sehr kurze Mischzeiten erzielt, die hohe Durchsätze in den winzigen Reaktoren ermöglichen. K. Jähnisch, V. Hessel et al. vermitteln in ihrem Aufsatz auf S. 410 ff. das eindrucksvolle Potenzial dieses jungen Forschungsgebiets.
Mikrostrukturreaktoren haben in den letzten Jahren in der chemischen Verfahrenstechnik deutlich an Bedeutung gewonnen: Erste Firmen, die Prozessanlagen mit Mikrostrukturreaktoren anbieten, sind am ...Markt, eine Reihe von Instituten erforscht dieses Gebiet, Universitäten bieten Lehrveranstaltungen an, und einige verfahrenstechnisch orientierte Übersichtsartikel liegen bereits vor. Mikrostrukturierte Systeme sind besonders wertvoll für die Untersuchung stark exothermer schneller Reaktionen. Durch isotherme Betriebsweise lassen sich viele thermisch induzierte Nebenreaktionen zurückdrängen, was sicherheitstechnische Vorteile bei Reaktionen mit gefährlichen Reaktanten bringt. Obwohl viele organische Synthesen mit besseren Ergebnissen als in konventionellen Reaktoren durchgeführt wurden, ist der Mikrostrukturreaktor‐Technologie der große Durchbruch in der präparativen Chemie noch nicht gelungen. Aus diesem Grund unterstreicht dieser Aufsatz die Vorteile von Mikrostrukturreaktoren bei Flüssigphasen‐, Gasphasen‐ und Gas‐Flüssigphasen‐Reaktionen.
Darfs auch ein bisschen kleiner sein? Mikrostrukturreaktoren sind wegen ihrer verkleinerten Dimensionen gegenüber konventionellen Industriereaktoren deutlich im Vorteil, z. B. bezüglich Umsatz, Selektivität und Sicherheit. Im vorliegenden Aufsatz werden die Parameter vorgestellt, die entscheidend für die Entwicklung und Optimierung von Prozessen in Mikrostrukturreaktoren sind.
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