Leibniz University of Hanover

About: Leibniz University of Hanover is a education organization based out in Hanover, Niedersachsen, Germany. It is known for research contribution in the topics: Finite element method & Computer science. The organization has 14283 authors who have published 29845 publications receiving 682152 citations.

Incorporation of EPA and DHA into plasma phospholipids in response to different omega-3 fatty acid formulations--a comparative bioavailability study of fish oil vs. krill oil

Abstract: Bioavailability of omega-3 fatty acids (FA) depends on their chemical form. Superior bioavailability has been suggested for phospholipid (PL) bound omega-3 FA in krill oil, but identical doses of different chemical forms have not been compared. In a double-blinded crossover trial, we compared the uptake of three EPA+DHA formulations derived from fish oil (re-esterified triacylglycerides [rTAG], ethyl-esters [EE]) and krill oil (mainly PL). Changes of the FA compositions in plasma PL were used as a proxy for bioavailability. Twelve healthy young men (mean age 31 y) were randomized to 1680 mg EPA+DHA given either as rTAG, EE or krill oil. FA levels in plasma PL were analyzed pre-dose and 2, 4, 6, 8, 24, 48, and 72 h after capsule ingestion. Additionally, the proportion of free EPA and DHA in the applied supplements was analyzed. The highest incorporation of EPA+DHA into plasma PL was provoked by krill oil (mean AUC0-72 h: 80.03 ± 34.71%*h), followed by fish oil rTAG (mean AUC0-72 h: 59.78 ± 36.75%*h) and EE (mean AUC0-72 h: 47.53 ± 38.42%*h). Due to high standard deviation values, there were no significant differences for DHA and the sum of EPA+DHA levels between the three treatments. However, a trend (p = 0.057) was observed for the differences in EPA bioavailability. Statistical pair-wise group comparison's revealed a trend (p = 0.086) between rTAG and krill oil. FA analysis of the supplements showed that the krill oil sample contained 22% of the total EPA amount as free EPA and 21% of the total DHA amount as free DHA, while the two fish oil samples did not contain any free FA. Further studies with a larger sample size carried out over a longer period are needed to substantiate our findings and to determine differences in EPA+DHA bioavailability between three common chemical forms of LC n-3 FA (rTAG, EE and krill oil). The unexpected high content of free EPA and DHA in krill oil, which might have a significant influence on the availability of EPA+DHA from krill oil, should be investigated in more depth and taken into consideration in future trials.

Mobile quantum gravity sensor with unprecedented stability

Abstract: Changes of surface gravity on Earth are of great interest in geodesy, earth sciences and natural resource exploration. They are indicative of Earth system's mass redistributions and vertical surface motion, and are usually measured with falling corner-cube- and superconducting gravimeters (FCCG and SCG). Here we report on absolute gravity measurements with a mobile quantum gravimeter based on atom interferometry. The measurements were conducted in Germany and Sweden over periods of several days with simultaneous SCG and FCCG comparisons. They show the best-reported performance of mobile atomic gravimeters to date with an accuracy of 39 nm/s^2, long-term stability of 0,5 nm/s^2 and short-term noise of 96 nm/s^2/(Hz)^1/2. These measurements highlight the unique properties of atomic sensors. The achieved level of performance in a transportable instrument enables new applications in geodesy and related Fields, such as continuous absolute gravity monitoring with a single instrument under rough environmental conditions.

It's a Hard Lock Life: A Field Study of Smartphone (Un)Locking Behavior and Risk Perception

Abstract: A lot of research is being conducted into improving the usability and security of phone-unlocking. There is however a severe lack of scientic data on users’ current unlocking behavior and perceptions. We performed an online survey (n = 260) and a one-month eld study ( n = 52) to gain insights into real world (un)locking behavior of smartphone users. One of the main goals was to nd out how much overhead unlocking and authenticating adds to the overall phone usage and in how many unlock interactions security (i.e. authentication) was perceived as necessary. We also investigated why users do or do not use a lock screen and how they cope with smartphone-related risks, such as shouldersurng or unwanted accesses. Among other results, we found that on average, participants spent around 2.9 % of their smartphone interaction time with authenticating (9 % in the worst case). Participants that used a secure lock screen like PIN or Android unlock patterns considered it unnecessary in 24.1 % of situations. Shoulder surng was perceived to be a relevant risk in only 11 of 3410 sampled situations.

Cyclopentadienylmetal complexes bearing pendant phosphorus, arsenic, and sulfur ligands.

Abstract: Bidendate ligands have proven important in a variety of complexes and are invaluable in a number of catalytic processes. While ligands of this type usually have two identical ligand fragments (homobidendate ligands), heterobidendate ligands allow for a differentiation of the ligands and therefore are prone to selective reactions. This is especially interesting in cases where the ligands are rather different from one another. Phosphane and cyclopentadienyl ligands are among the most commonly used in organometallic chemistry, and they are quite different in nature: Whereas a phosphane is electroneutral and often subjected to ligand exchange processes, the cyclopentadienyl ligand is normally considered to be negatively charged and rather tightly bound to a metal. Reviewing the literature in the field of cyclopentadienylmetal complexes bearing pendant phosphorus, arsenic, and sulfur ligands is timely given that the number of publications of relevance to this topic is growing exponentially as can easily be seen from the list of references in this review: the number of references since 1993 clearly exceeds that of all years before. The reason for this development may be that cyclopentadienylmetal complexes bearing pendant phosphorus, arsenic, and sulfur ligands are expected to perform chemistry different from that of usual cyclopentadienyl complexes. Indeed this has often been the case. Complexes discussed in this review facilitate the complexation of sensitive ligands, offer new aspects concerning chirality, allow novel reactions, and are beginning to be applied to transition metal catalysis. It is therefore hoped that this review will contribute to these developments by offering state of the art information for those active in the field and, even more important, for those who join in the future. This review covers the chemistry of cyclopentadienylmetal complexes, in which the cyclopentadienyl ligand bears a sidearm which includes a phosphorus, arsenic, or sulfur ligand. The pendant ligand has to be separated from the cyclopentadienyl part, that is, † Dedicated to Professor Günther Wilke on the occasion of his 75th birthday. * To whom correspondence should be addressed. Fax: +49/(0)511/ 762-4616. E-mail: holger.butenschoen@mbox.oci.uni-hannover.de. Holger Butenschön was born and raised in Hamburg, Germany. After his army service he studied chemistry at the University of Hamburg and obtained his Dr. rer. nat. degree in 1983 with Professor Armin de Meijere as a fellow of the Studienstiftung des Deutschen Volkes. From 1983 to 1984 he spent a postdoctoral year with Professor K. Peter C. Vollhardt at the University of California at Berkeley as a NATO fellow. Having returned to Germany, he joined the Max-Planck-Institut für Kohlenforschung in Mülheim an der Ruhr as a Liebig fellow to do preparative organometallic work in the fields of anellated arenechromium complexes and cyclopentadienyl cobalt complexes with pendant phosphane ligands. After his habilitation in 1991 (University of Hamburg), he became a Heisenberg fellow of the DFG at the University of Wuppertal from 1992 to 1993. Since 1993 he has been a professor of organic chemistry at the University of Hannover. In 1999 he was a foreign visiting professor at Kyushu University in Fukuoka, Japan. Holger Butenschön is the editor of the German translation of Peter Vollhardt’s and Neil Schore’s textbook Organic Chemistry as well as a coauthor of the Memofix OC. He currently serves as the chairman of the Hannover district of the German Chemical Society (GDCh). His spare time is occupied by the female part of his family, his wife Bettina and their four daughters Lisa, Nora, Inga, and Lara. 1527 Chem. Rev. 2000, 100, 1527−1564