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.

AFLP markers as a tool to reconstruct complex relationships: A case study in Rosa (Rosaceae)

Abstract: The genus Rosa has a complex evolutionary history caused by several factors, often in conjunction: extensive hybridization, recent radiation, incomplete lineage sorting, and multiple events of polyploidy. We examined the applicability of AFLP markers for reconstructing (species) relationships in Rosa, using UPGMA clustering, Wagner parsimony, and Bayesian inference. All trees were well resolved, but many of the deeper branches were weakly supported. The cluster analysis showed that the rose cultivars can be separated into a European and an Oriental cluster, each being related to different wild species. The phylogenetic analyses showed that (1) two of the four subgenera (Hulthemia and Platyrhodon) do not deserve subgeneric status; (2) section Carolinae should be merged with sect. Cinnamomeae; (3) subsection Rubigineae is a monophyletic group within sect. Caninae, making sect. Caninae paraphyletic; and (4) there is little support for the distinction of the five other subsections within sect. Caninae. Comparison of the trees with morphological classifications and with previous molecular studies showed that all methods yielded reliable trees. Bayesian inference proved to be a useful alternative to parsimony analysis of AFLP data. Because of their genome-wide sampling, AFLPs are the markers of choice to reconstruct (species) relationships in evolutionary complex groups.

Coffee berry borer Hypothenemus hampei (Coleoptera: Curculionidae): searching for sustainable control strategies.

Abstract: The coffee berry borer Hypothenemus hampei (Ferrari) is the most serious pest of the world's most valuable tropical export crop Since the last review on this insect was published six years ago, many new studies have contributed to an improved insight into the biology and ecology of the beetle, and have indicated new avenues for integrated and biological control The latest developments in research, both laboratory and field, on the pest, its natural enemies and their implications for integrated control of H hampei are summarized, with a particular focus on the situation in The Americas Lately, the global coffee industry has changed radically; it has suffered a long cycle of lowest-ever world market prices caused by overproduction and technological change At the same time, the advent of sustainable certification schemes has had a major impact on the industry The role of integrated pest management and biological control of H hampei in an era of changes in the coffee industry is discussed

Perovskite Hollow-Fiber Membranes for the Production of Oxygen-Enriched Air†

Abstract: Oxygen-enriched air with 30–50 vol%O2 is used in a number of industrial processes, for example, in the synthesis of ammonia, the Claus process, and the regeneration of the catalyst for the fluid-catalytic-cracking (FCC) process. Another application of O2-enriched air is the most efficient use of methane in high-temperature furnaces or cement kilns. There are different methods for producing O2enriched air, mainly by mixing air with pure O2 obtained from a cryogenic technique or pressure swing adsorption (PSA). However, these techniques require high capital investment and operational costs. Depending on the O2 concentration and the amount of the O2-enriched air needed, membrane technology can be competitive. As organic polymeric hollow-fiber membranes have a separation factor between 2 and 6, a single-stage membrane permeation gives an O2 concentration typically of the order of 30– 50 vol% under a pressure difference of about 10 bar. Although higher O2 concentration and permeability can be achieved by increasing the feed flow rate, by reducing the membrane thickness, or by increasing the pressure difference, these actions increase the separation costs. Furthermore, the organic polymeric membrane cannot be used for the recovery of heat from exhaust gas in high-temperature processes. Herein we propose a new technique to produce O2enriched air by using a mixed-ion and electron-conducting (MIEC) perovskite membrane. The basic idea is shown in Figure 1. At elevated temperatures, under a slight difference in air pressure (1–2 bar) O2 can be transported through a MIEC perovskite membrane in the form of oxygen ions from the side of high air pressure to the side of low air pressure. Simultaneously, electrons are transported in the opposite direction to maintain electric neutrality. The permeated O2 increases the O2 concentration to typically 30–50 vol% in the sweep air that forms the O2-enriched air on the low-pressure side. Therefore, the perovskite membrane combines the in situ O2 supply with permeated O2 and air in one unit thus simplifying the process of O2 enrichment and reducing the operational and capital costs. The obvious advantage of using perovskite membranes is their 100% selectivity for O2. Usually, polymeric membranes also transport noble or inert gases such as Ar or CO2, which can be disadvantageous depending on the process. Synthesis gas for ammonia production, for example, is prepared at a pressure level of about 30 bar and afterwards compressed to a pressure of typically 170–190 bar. Any inert gases contained within the synthesis gas are also compressed to a higher pressure and fed into the synthesis loop. This in turn increases the energy expenditure for compression, the necessary loop volume, and the purge flow used to get rid of the inert components in the synthesis loop. Moreover, compared with hollow-fiber membranes made from organic polymers, the perovskite hollow-fiber membrane requires a lower pressure difference (1–2 bar) across the membrane and can work at elevated temperatures, thus allowing high-temperature heat exchange. O2-enriched air is used mostly in high-temperature oxidation processes such as in the generation of synthesis gas for ammonia production in which O2-enriched air is used to run a secondary reformer typically operated at 1000 to 1100 8C. Therefore, in this process the temperature required to operate the perovskite hollow fiber is already available and can be used by heat exchange. Furthermore, the heat used for the O2 enrichment is not consumed, for example, in an endothermic reaction and can be regained by heat exchange with the product streams that leave the O2-permeation-membrane module. A similar setup may also apply to other applications for O2 enrichment with perovskite membranes, for example, the temperature increase of firing systems in power plants or industrial furnaces. The perovskite of composition BaCoxFeyZrzO3 d (BCFZ; x+y+z= 1.0) is a novel O2-permeable membrane with high O2 permeation fluxes and excellent thermal and mechanical stability. 5] BCFZ was used in a hollow-fiber configuration as [*] Dr. H. Wang, Prof. Dr. J. Caro Institut f!r Physikalische Chemie und Elektrochemie Universit,t Hannover Callinstrasse 3–3A, 30167 Hannover (Germany) Fax: (+49)511-762-19121 E-mail: haihui.wang@pci.uni-hannover.de