Microfluidic concentration of bacteria by on-chip electrophoresis     

Puchberger-Enengl D  Podszun S  Heinz H  Hermann C  Vulto P  Urban GA 《Biomicrofluidics》2011,5(4):044111-044111-10

In this contribution, we present a system for efficient preconcentration of pathogens without affecting their viability. Development of miniaturized molecular diagnostic kits requires concentration of the sample, molecule extraction, amplification, and detection. In consequence of low analyte concentrations in real-world samples, preconcentration is a critical step within this workflow. Bacteria and viruses exhibit a negative surface charge and thus can be electrophoretically captured from a continuous flow. The concept of phaseguides was applied to define gel membranes, which enable effective and reversible collection of the target species. E. coli of the strains XL1-blue and K12 were used to evaluate the performance of the device. By suppression of the electroosmotic flow both strains were captured with efficiencies of up to 99%. At a continuous flow of 15 μl/min concentration factors of 50.17 ± 2.23 and 47.36 ± 1.72 were achieved in less than 27 min for XL1-blue and K12, respectively. These results indicate that free flow electrophoresis enables efficient concentration of bacteria and the presented device can contribute to rapid analyses of swab-derived samples.  相似文献   

Determinants of bone mineral density in patients on haemodialysis or peritoneal dialysis – a cross-sectional,longitudinal study     

Mads Nybo  Bente Jespersen  Michael Aarup  Charlotte Ejersted  Anne Pernille Hermann  Kim Brixen 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2013,23(3):342-350

Introduction:

The aim of the study was to identify biomarkers of alteration in bone mineral density (BMD) in patients on haemodialysis (HD) and peritoneal dialysis (PD).

Materials and methods:

In a cross-sectional, longitudinal study dual-energy X-ray absorptiometry scans were performed in 146 HD-patients and 28 PD-patients. Follow-up after 14 months (mean) was conducted in 73 patients. As potential biomarkers we investigated parathyroid hormone (PTH), 25-hydroxy vitamin-D, ionised calcium, albumin, phosphate, and total alkaline phosphatases (t-ALP).

Results:

Both groups of dialysis patients had lower BMD in the femoral neck (BMD_neck) (P < 0.001) and forearm (BMD_forearm) (P < 0.001) compared to healthy controls, but comparable BMD in the lumbar spine (BMD_spine). BMD did not differ between dialysis types, but patients ever-treated with glucocorticoids had significantly lower BMD, while patients with polycystic kidney disease had higher BMD. BMD correlated with body weight, actual age, age at initiation of dialysis, duration of dialysis and levels of PTH and t-ALP. However, t-ALP only remained associated with low BMD_spine after adjusting for other factors (P = 0.001). In the follow-up study all patients had decreased BMD in all three locations, but only for the lumbar spine there was a significant association between BMD and the bone markers t-ALP (P = 0.009) and PTH (P = 0.013).

Conclusions:

Both HD and PD patients have low BMD, and increased concentrations of t-ALP is associated BMD_spine after adjustment, while PTH and t-ALP is associated with decrease in BMD_spine over time. This substantiates the use of these biomarkers in both types of dialysis patients.  相似文献   

Karl Jaspers     

Hermann Horn 《Prospects》1993,23(3-4):721-739

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„Von Weimar nach PISA“     

Hermann Lange 《Zeitschrift für Erziehungswissenschaft》2003,6(3):449-457

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Zwischen Kontrolle und Demokratisierung: Die Sportpolitik der französischen Besatzungsmacht in Südwest     

Stefanie Woite-Wehle  Hermann Rieder 《Sportwissenschaft》2002,32(4):453-458

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The development of archival science as a scholarly discipline     

Hermann Rumsch?ttel 《Archival Science》1987,1(2):143-155

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Performance of students in project‐based science classrooms on a national measure of science achievement     

Rebecca M. Schneider  Joseph Krajcik  Ronald W. Marx  Elliot Soloway 《科学教学研究杂志》2002,39(5):410-422

Reform efforts in science education emphasize the importance of supporting students' construction of knowledge through inquiry. Project‐based science (PBS) is an ambitious approach to science instruction that addresses concerns of reformers. A sample of 142 10th‐ and 11th‐grade students enrolled in a PBS program completed the 12th‐grade 1996 National Assessment of Educational Progress (NAEP) science test. Compared with subgroups identified by NAEP that most closely matched our student sample, White and middle class, PBS students outscored the national sample on 44% of NAEP test items. This study shows that students participating in a PBS curriculum were prepared for this type of testing. Educators should be encouraged to use inquiry‐based approaches such as PBS to implement reform in their schools. © 2002 Wiley Periodicals, Inc. J Res Sci Teach 39: 410–422, 2002  相似文献   

Engineering Education and the Status of Industry     

Hermann Bayer  Peter Lawrence 《European Journal of Engineering Education》1977,2(3):223-227

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Exploring student study behaviours in engineering: how undergraduates prepared textbook problems for online submission     

Angela Minichiello  Sherry Marx  Laurie McNeill  Christine Hailey 《European Journal of Engineering Education》2019,44(1-2):253-270

ABSTRACT

While textbooks serve as a primary source of content material and problem-solving practice for undergraduates in engineering, studies that investigate how engineering students prepare assignments based on textbook problems are limited. To examine how engineering students complete textbook-based assignments outside of class, this exploratory qualitative study retrospectively investigated the study behaviours of six undergraduates enrolled in a required, second-year undergraduate engineering course at a mid-size, public university in the western United States. Within the course, students solved textbook problems and electronically submitted problem answers for graded credit. Findings from in-depth, semi-structured interviews showed that students identified and used a variety of non-traditional and unsupported resources in personalised approaches to preparing assignments. Resource choice and use was affected by students’ preferences for timely support, convenience, and social connections. The online submission process seemed to influence students’ adoption of study behaviours and resources considered less effective for deep, conceptual learning.  相似文献   

The supply of information on chemical reactions in the IDC system     

Robert Fugmann  Günter Kusemann  Jakob Hermann Winter 《Information processing & management》1979,15(6):303-323

The possibilities and limitations of chemical reaction names as the basis for retrieving literature dealing with reaction types are briefly reviewed, as well as the capability of a mere substructure search in a file of reactants and products. It is demonstrated that reaction indexing ideally should be based on the identification of the reaction sites of the molecules involved, as well as on the representation of various kinds of relations between these reactive centers. The GREMAS reaction indexing of IDC is discussed as an example. Before a chemist can request information on reaction types that appear promising for a certain target molecule, he must be aware of their existence. The task of computer-assisted synthesis design is to submit suggestions of conceivable synthetic pathways to a target structure and so to alert the chemist to syntheses of which he had not yet been aware. The “reverse retrieval” technique is demonstrated to constitute a fundamental principle for this kind of information supply. If sufficiently developed and assisted by an effective system for the documentation and classification of reaction types, it can provide suggestions for syntheses at a considerable efficiency without requiring completion by additional principles. The IDC system of (Sub-) Structure search seems to be able to serve this purpose too, due to its flexibility, economics, and precision. The reverse retrieval offers solutions to a number of problems hitherto unresolved in information science.  相似文献