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Keywords = Kühni

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13 pages, 853 KiB  
Article
Urolithiasis as a Husbandry Risk to Yaks in the Swiss Alps
by Michael Hässig, Natascha Biner, Christian Gerspach, Hubertus Hertzberg, Michaela Kühni, Claude Schelling and Annette Liesegang
Animals 2024, 14(19), 2915; https://doi.org/10.3390/ani14192915 - 9 Oct 2024
Viewed by 1335
Abstract
Background: Between 2006 and 2014, 10 cases of urolithiasis in yaks with calcium carbonate uroliths were confirmed in Switzerland, and at the same time, a sixfold calcium overhang in roughage in an affected farm was evident. The purpose of this study was the [...] Read more.
Background: Between 2006 and 2014, 10 cases of urolithiasis in yaks with calcium carbonate uroliths were confirmed in Switzerland, and at the same time, a sixfold calcium overhang in roughage in an affected farm was evident. The purpose of this study was the question of whether urolithiasis in yaks in the alpine regions of Switzerland poses a husbandry risk. The hypothesis was that elevated calcium levels in roughage led to hypercalcemia and, thus, the formation of calcium carbonate stones. Methods: Blood samples from 99 animals from 10 farms were examined (n = 6 problem farms; n = 4 control farms). Several metabolites were analyzed in the blood and urine. In addition, roughage, soil, and water samples were analyzed. The farms were distributed within different regions of Switzerland. Results: This study revealed different Ca:P ratios, from 1.56 to 7.74:1, in the forages and mild hypercalcemia in the animals of the problem farms. In a univariate analysis of the problem versus control farms, about 20 other significant factors emerged. Multivariate analysis showed that altitude, CP (crude protein), P, Mg, NDF, and ADF in the diet are important factors. Based on analysis of the pedigree, there was no evidence of an obvious genetic background of urolithiasis. Limitations: A limitation of this study is the small number of yaks in Switzerland. Conclusions: The question of whether urolithiasis in yaks in alpine Switzerland poses a husbandry risk can be answered affirmatively. Calcium-rich forages play a crucial role in this multifactorial process. Full article
(This article belongs to the Section Veterinary Clinical Studies)
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21 pages, 5255 KiB  
Article
Systematic and Model-Assisted Process Design for the Extraction and Purification of Artemisinin from Artemisia annua L.—Part II: Model-Based Design of Agitated and Packed Columns for Multistage Extraction and Scrubbing
by Axel Schmidt, Maximilian Sixt, Maximilian Johannes Huter, Fabian Mestmäcker and Jochen Strube
Processes 2018, 6(10), 179; https://doi.org/10.3390/pr6100179 - 2 Oct 2018
Cited by 10 | Viewed by 5480
Abstract
Liquid-liquid extraction (LLE) is an established unit operation in the manufacturing process of many products. However, development and integration of multistage LLE for new products and separation routes is often hindered and is probably more cost intensive due to a lack of robust [...] Read more.
Liquid-liquid extraction (LLE) is an established unit operation in the manufacturing process of many products. However, development and integration of multistage LLE for new products and separation routes is often hindered and is probably more cost intensive due to a lack of robust development strategies and reliable process models. Even today, extraction columns are designed based on pilot plant experiments. For dimensioning, knowledge of phase equilibrium, hydrodynamics and mass transport kinetics are necessary. Usually, those must be determined experimentally for scale-up, at least in scales of DN50-150 (nominal diameter). This experiment-based methodology is time consuming and it requires large amounts of feedstock, especially in the early phase of the project. In this study the development for the integration of LLE in a new manufacturing process for artemisinin as an anti-malaria drug is presented. For this, a combination of miniaturized laboratory and mini-plant experiments supported by mathematical modelling is used. System data on extraction and washing distributions were determined by means of shaking tests and implemented as a multi-stage extraction in a process model. After the determination of model parameters for mass transfer and plant hydrodynamics in a droplet measurement apparatus, a distributed plug-flow model is used for scale-up studies. Operating points are validated in a mini-plant system. The mini-plant runs are executed in a Kühni-column (DN26) for extraction and a packed extraction column (DN26) for the separation of side components with a throughput of up to 3.6 L/h, yield of up to 100%, and purity of 41% in the feed mixture to 91% after washing. Full article
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