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排序方式: 共有2100条查询结果,搜索用时 15 毫秒
101.
Noei Maziar Luckner Paul Linn Tobias Jungemann Christoph 《Journal of Computational Electronics》2022,21(1):153-168
Journal of Computational Electronics - We discuss the numerical aspects of the Boltzmann transport equation (BE) for electrons in semiconductor devices, which is stabilized by Godunov’s... 相似文献
102.
Devender S. Negi Felix Sobotka Tobias Kimmel Günter Wozny Reinhard Schomäcker 《Journal of the American Oil Chemists' Society》2007,84(1):83-90
The present work focused on the glycerolysis of fatty acid methyl esters. The aim was to develop and test a kinetic model
that could be used to reliably simulate different process alternatives for this reaction. A prerequisite was the identification
and characterization of the factors that affect the reaction kinetics. Experiments were carried out in a batch reactor with
and without forced removal of methanol, which is one of the reaction products. Concentrations of all components in the two-phase
system were measured. It was found that the methanol concentration has a strong effect on the reaction rate and equilibrium
conversion. Near-complete conversions were obtained by stripping methanol with an inert gas. The glycerol concentration in
the ester phase was found to increase as the reaction proceeds, which also accelerates the reaction. Effects of mass transfer
on the reaction rate were not found to control the reaction rate under well-agitated conditions. A semi-empirical model was
used to simulate the reaction. The results from the semi-empirical model show good agreement with experimental results. 相似文献
103.
Marie Burns Lennard Ostendorf Robert Biesen Andreas Grützkau Falk Hiepe Henrik E. Mei Tobias Alexander 《International journal of molecular sciences》2021,22(5)
Given its uniformly high expression on plasma cells, CD38 has been considered as a therapeutic target in patients with systemic lupus erythematosus (SLE). Herein, we investigate the distribution of CD38 expression by peripheral blood leukocyte lineages to evaluate the potential therapeutic effect of CD38-targeting antibodies on these immune cell subsets and to delineate the use of CD38 as a biomarker in SLE. We analyzed the expression of CD38 on peripheral blood leukocyte subsets by flow and mass cytometry in two different cohorts, comprising a total of 56 SLE patients. The CD38 expression levels were subsequently correlated across immune cell lineages and subsets, and with clinical and serologic disease parameters of SLE. Compared to healthy controls (HC), CD38 expression levels in SLE were significantly increased on circulating plasmacytoid dendritic cells, CD14++CD16+ monocytes, CD56+ CD16dim natural killer cells, marginal zone-like IgD+CD27+ B cells, and on CD4+ and CD8+ memory T cells. Correlation analyses revealed coordinated CD38 expression between individual innate and memory T cell subsets in SLE but not HC. However, CD38 expression levels were heterogeneous across patients, and no correlation was found between CD38 expression on immune cell subsets and the disease activity index SLEDAI-2K or established serologic and immunological markers of disease activity. In conclusion, we identified widespread changes in CD38 expression on SLE immune cells that highly correlated over different leukocyte subsets within individual patients, but was heterogenous within the population of SLE patients, regardless of disease severity or clinical manifestations. As anti-CD38 treatment is being investigated in SLE, our results may have important implications for the personalized targeting of pathogenic leukocytes by anti-CD38 monoclonal antibodies. 相似文献
104.
Anna Sib Tobias M. Milzarek Alexander Herrmann Dr. Lila Oubraham Jonas I. Müller Prof. Dr. Andreas Pichlmair Prof. Dr. Ruth Brack-Werner Prof. Dr. Tobias A. M. Gulder 《Chembiochem : a European journal of chemical biology》2020,21(4):492-495
Sorbicillinoids are fungal polyketides characterized by highly complex and diverse molecular structures, with considerable stereochemical intricacy combined with a high degree of oxygenation. Many sorbicillinoids possess promising biological activities. An interesting member of this natural product family is sorbicatechol A, which is reported to have antiviral activity, particularly against influenza A virus (H1N1). Through a straightforward, one-pot chemoenzymatic approach with recently developed oxidoreductase SorbC, the characteristic bicyclo[2.2.2]octane core of sorbicatechol is structurally diversified by variation of its natural 2-methoxyphenol substituent. This facilitates the preparation of a focused library of structural analogues bearing substituted aromatic systems, alkanes, heterocycles, and ethers. Fast access to this structural diversity provides an opportunity to explore the antiviral potential of the sorbicatechol family. 相似文献
105.
Merjo Laine Tobias Rütting Laura Alakukku Ansa Palojärvi Rauni Strömmer 《Nutrient Cycling in Agroecosystems》2018,110(1):39-49
No-till is considered an agricultural practice beneficial for the environment as soil erosion is decreased compared to ploughed soils. For on overall evaluation of the benefits and disadvantages of this crop production method, understanding the soil nutrient cycle is also of importance. The study was designed to obtain information about gross soil nitrogen (N) process rates in boreal no-tilled and mouldboard ploughed spring barley (Hordeum vulgare L.) fields after autumn harvesting. In situ soil gross N transformation process rates were quantified for the 5 cm topsoil in 9 days’ incubation experiment using 15N pool dilution and tracing techniques and a numerical 15N tracing model. Gross N mineralization into ammonium (NH4 +) and NH4 + immobilization were the most important N transformation processes in the soils. The gross mineralization rate was 14% and NH4 + immobilization rate 64% higher in no-till than in ploughing. Regardless of the faster mineralization, the gross rate of NH4 + oxidation into nitrate (NO3 ?) in no-till was one order of magnitude lower compared the ploughing. The results indicate that the no-tilled soils have the potential to decrease the risk for NO3 ? leaching due to slower NH4 + oxidation. 相似文献
106.
Florian Witzgall Tobias Depke Dr. Michael Hoffmann Dr. Martin Empting Prof. Dr. Mark Brönstrup Prof. Dr. Rolf Müller Prof. Dr. Wulf Blankenfeldt 《Chembiochem : a European journal of chemical biology》2018,19(14):1531-1544
Pseudomonas aeruginosa is a bacterial pathogen that causes life‐threatening infections in immunocompromised patients. It produces a large armory of saturated and mono‐unsaturated 2‐alkyl‐4(1H)‐quinolones (AQs) and AQ N‐oxides (AQNOs) that serve as signaling molecules to control the production of virulence factors and that are involved in membrane vesicle formation and iron chelation; furthermore, they also have, for example, antibiotic properties. It has been shown that the β‐ketoacyl‐acyl‐carrier protein synthase III (FabH)‐like heterodimeric enzyme PqsBC catalyzes the last step in the biosynthesis of the most abundant AQ congener, 2‐heptyl‐4(1H)‐quinolone (HHQ), by condensing octanoyl‐coenzyme A (CoA) with 2‐aminobenzoylacetate (2‐ABA), but the basis for the large number of other AQs/AQNOs produced by P. aeruginosa is not known. Here, we demonstrate that PqsBC uses different medium‐chain acyl‐CoAs to produce various saturated AQs/AQNOs and that it also biosynthesizes mono‐unsaturated congeners. Further, we determined the structures of PqsBC in four different crystal forms at 1.5 to 2.7 Å resolution. Together with a previous report, the data reveal that PqsBC adopts open, intermediate, and closed conformations that alter the shape of the acyl‐binding cavity and explain the promiscuity of PqsBC. The different conformations also allow us to propose a model for structural transitions that accompany the catalytic cycle of PqsBC that might have broader implications for other FabH‐enzymes, for which such structural transitions have been postulated but have never been observed. 相似文献
107.
108.
Vassiliki Damakoudi Tobias Feldner Edina Dilji Andrey Belkin Prof. Clemens Richert 《Chembiochem : a European journal of chemical biology》2021,22(5):924-930
Messenger RNA (mRNA) is emerging as an attractive biopolymer for therapy and vaccination. To become suitable for vaccination, mRNA is usually converted to a biomaterial, using cationic peptides, polymers or lipids. An alternative form of converting mRNA into a material is demonstrated that uses branched oligoribonucleotide hybrids with the ability to hybridize with one or more regions of the mRNA sequence. Two such hybrids with hexamer arms and adamantane tetraol as branching element were prepared by solution-phase synthesis. When a rabies mRNA was treated with the branched hybrids at 1 M NaCl concentration, biomaterials formed that contained both of the nucleic acids. These results show that branched oligoribonucleotides are an alternative to the often toxic reagents commonly used to formulate mRNA for medical applications. 相似文献
109.
Dr. Sandra Liebscher Dr. Sebastian Mathea Dr. Tobias Aumüller Dr. Andreas Pech Prof. Dr. Frank Bordusa 《Chembiochem : a European journal of chemical biology》2021,22(7):1201-1204
Fluorescent fusion proteins are powerful tools for studying biological processes in living cells, but universal application is limited due to the voluminous size of those tags, which might have an impact on the folding, localization or even the biological function of the target protein. The designed biocatalyst trypsiligase enables site-directed linkage of small-sized fluorescence dyes on the N terminus of integral target proteins located in the outer membrane of living cells through a stable native peptide bond. The function of the approach was tested by using the examples of covalent derivatization of the transmembrane proteins CD147 as well as the EGF receptor, both presented on human HeLa cells. Specific trypsiligase recognition of the site of linkage was mediated by the dipeptide sequence Arg-His added to the proteins’ native N termini, pointing outside the cell membrane. The labeling procedure takes only about 5 minutes, as demonstrated for couplings of the fluorescence dye tetramethyl rhodamine and the affinity label biotin as well. 相似文献
110.
Lukas Martin Patrick Koczera Nadine Simons Elisabeth Zechendorf Janine Hoeger Gernot Marx Tobias Schuerholz 《International journal of molecular sciences》2016,17(3)
Sepsis is the most common cause of death in intensive care units and associated with widespread activation of host innate immunity responses. Ribonucleases (RNases) are important components of the innate immune system, however the role of RNases in sepsis has not been investigated. We evaluated serum levels of RNase 1, 3 and 7 in 20 surgical sepsis patients (Sepsis), nine surgical patients (Surgery) and 10 healthy controls (Healthy). RNase 1 and 3 were elevated in Sepsis compared to Surgery (2.2- and 3.1-fold, respectively; both p < 0.0001) or compared to Healthy (3.0- and 15.5-fold, respectively; both p < 0.0001). RNase 1 showed a high predictive value for the development of more than two organ failures (AUC 0.82, p = 0.01). Patients with renal dysfunction revealed higher RNase 1 levels than without renal dysfunction (p = 0.03). RNase 1 and 3 were higher in respiratory failure than without respiratory failure (p < 0.0001 and p = 0.02, respectively). RNase 7 was not detected in Healthy patients and only in two patients of Surgery, however RNase 7 was detected in 10 of 20 Sepsis patients. RNase 7 was higher in renal or metabolic failure than without failure (p = 0.04 and p = 0.02, respectively). In conclusion, RNase 1, 3 and 7 are secreted into serum under conditions with tissue injury, such as major surgery or sepsis. Thus, RNases might serve as laboratory parameters to diagnose and monitor organ failure in sepsis. 相似文献