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  • 1
    Language: English
    In: The Journal of organic chemistry, 16 March 2018, Vol.83(6), pp.3069-3077
    Description: The arene ring of the title compounds is cleaved by a reaction cascade which is initiated by an intramolecular ortho photocycloaddition reaction. Tricyclic products were obtained in a highly regio- and diastereoselective fashion via a cyclooctatriene intermediate. The facial diastereoselectivity exerted by a stereogenic center in the tether is moderate to good (dr = 65/35 to 82/18). Yields were acceptable (44-87%) except for a single substrate which had a geminal dimethyl substitution in the tether and which gave the respective product in only 14% yield. The reaction is stereoconvergent with regard to the olefin configuration ( E or Z) in agreement with a triplet mechanism of the ortho photocycloaddition step.
    ISSN: 00223263
    E-ISSN: 1520-6904
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  • 2
    Language: English
    In: Palaeogeography, Palaeoclimatology, Palaeoecology, Oct 1, 2013, Vol.387, p.165(11)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.palaeo.2013.07.023 Byline: Roland Zech, Michael Zech, Slobodan MarkoviA, Ulrich Hambach, Yongsong Huang Abstract: Loess-paleosol sequences (LPS) provide unique terrestrial archives for past environmental and climate changes. The loess units are generally interpreted to reflect more arid conditions, whereas paleosols are thought to document more humid conditions. This paradigm may, however, deserve to be challenged in some regions, because it does not take into account past changes in dust accumulation rates. Here we present a multi-proxy sedimentological and geochemical characterization of the LPS Crvenka, Serbia, spanning the last ~140ka. Commonly used analyses, such as magnetic susceptibility, organic carbon content, grain size and weathering indices, allow the quantification of the intensity of pedogenesis. However, loess accumulation rates were much higher during glacials than during interglacials, so that it is not trivial to infer past rates of pedogenesis and related paleoclimate conditions. Novel proxies, based for example on lipid biomarkers and their isotopic composition, are not so directly affected by changes in loess accumulation rates and might provide interesting new insights. Long-chain, plant-derived n-alkanes in the LPS Crvenka suggest a minor, but non-negligible contribution of deciduous trees and shrubs (C.sub.27 and C.sub.29) during MIS 1, 2, 4 and 6, whereas grasses and herbs (C.sub.31 and C.sub.33) dominate the alkane input during MIS 3 and 5. This is in agreement with the notion that parts of southeast Europe served as refugia for deciduous trees during glacials. On the other hand, edaphic conditions on the drought-prone loess plateaus seem to have been more arid during MIS 3 and 5. Compound-specific [delta]D analyses on the alkanes show only little changes on glacial-interglacial timescale. When compared with the isotopic enrichment of the Mediterranean Sea during the last glacial, this likely indicates a complex combination of reduced temperatures, increased rainfall, reduced evapotranspiration and more advection of North Atlantic moisture. Although disentangling these factors is difficult, interpretation in terms of humid glacials and more arid interglacials seems to be supported also by other novel lipid biomarkers, so-called GDGTs (glycerol dialkyl glycerol tetraethers). Article History: Received 20 December 2012; Revised 9 July 2013; Accepted 23 July 2013
    Keywords: Climate -- Analysis ; Glycerol -- Analysis ; Proxy -- Analysis ; Interglacial Periods -- Analysis ; Rain -- Analysis ; Loess -- Analysis
    ISSN: 0031-0182
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: Fertility and Sterility, 2011, Vol.95(8), pp.2784-2785
    Description: Because of its size of 32 kDa and physicochemical properties, urinary FSH cannot permeate intact skin. We report the first pregnancy after laser microporation and transdermal delivery of FSH for ovarian superovulation as a substitute for SC or IM injections.
    Keywords: Transdermal Drug Delivery ; Laser Skin Microporation ; Large Molecular Weight Compound ; Ovarian Superovulation ; Hyperstimulation ; Follicle Stimulating Hormone ; Pregnancy ; Medicine
    ISSN: 0015-0282
    E-ISSN: 1556-5653
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  • 4
    Language: English
    In: Journal of Hydrology, 2015, Vol.529, p.622(10)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jhydrol.2014.10.012 Byline: Johannes Hepp, Mario Tuthorn, Roland Zech, Ines Mugler, Frank Schlutz, Wolfgang Zech, Michael Zech Abstract: * [delta].sup.2H biomarker record was established for a lake sediment archive. * 16ka [delta].sup.18O.sub.sugar and [delta].sup.2H.sub.n .sub.-alkane biomarker records follow similar trends. * [delta].sup.18O/[delta].sup.2H differences are explained by evaporative isotopic enrichment of lake water. * Reconstructed d-excess of lake water serves as proxy for evaporative losses. * A coupled [delta].sup.18O-[delta].sup.2H approach allows a model-based reconstruction of [delta].sup.18O/[delta].sup.2H.sub.prec.
    Keywords: Precipitation (Meteorology) – Analysis
    ISSN: 0022-1694
    Source: Cengage Learning, Inc.
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  • 5
    Language: English
    In: Palaeogeography, Palaeoclimatology, Palaeoecology, Jan 1, 2013, Vol.369, p.253(9)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.palaeo.2012.10.031 Byline: Roland Zech, Ines Rohringer, Pjotr Sosin, Hamdam Kabgov, Silke Merchel, Shavkat Akhmadaliev, Wolfgang Zech Keywords: Cosmogenic nuclides; Quaternary; Paleoclimate; Central Asia; Tajikistan Abstract: Mountain glaciers are sensitive indicators for climate change, especially with regard to summer temperature and precipitation. Glacial chronologies from Central Asia have therefore been suggested to provide valuable information about past changes in temperature, as well as precipitation and related changes in atmospheric circulation. However, available age control is still sparse. Here we present a glacial chronology for the Gissar Range, Tajikistan, based on thirteen.sup.10Be surface exposure ages. Prominent moraine lobes document glacial advances in phase with the global Last Glacial Maximum (LGM) during Marine Isotope Stage (MIS) 2. Rapid and significant deglaciation occurred already at ~20ka as inferred from recessional stages. An older and slightly more extensive glaciation could be dated to MIS 4, whereas the timing of the most extensive glaciation remains speculative. In contrast to the glacial chronologies from the nearby, more arid Pamir and Tien Shan, where MIS 3 and MIS 5 moraines likely document past periods with increased precipitation, glaciers in the more humid Gissar Range predominantly recorded past changes in temperature and summer insolation. Article History: Received 17 April 2012; Revised 24 September 2012; Accepted 17 October 2012
    Keywords: Glaciers ; Moraines ; Precipitation (Meteorology) ; Global Temperature Changes
    ISSN: 0031-0182
    Source: Cengage Learning, Inc.
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  • 6
    In: Journal of Strength and Conditioning Research, 2012, Vol.26(4), pp.1162-1168
    Description: ABSTRACT: Zech, A, Steib, S, Hentschke, C, Eckhardt, H, and Pfeifer, K. Effects of localized and general fatigue on static and dynamic postural control in male team handball athletes. J Strength Cond Res 26(4): 1162–1168, 2012–In team sports, sensorimotor impairments resulting from previous injuries or muscular fatigue have been suggested to be factors contributing to an increased injury risk. Although it has been widely shown that physical fatigue affects static postural sway, it is still questionable as to what extent these adaptations are relevant for dynamic, sports-related situations. The objective of this study was to determine the effects of whole-body and localized fatigue on postural control in stable and unstable conditions. Nineteen male team handball players were assessed in 2 sessions separated by 1 week. Treadmill running and single-leg step-up exercises were used to induce physical fatigue. The main outcome measures were center of pressure (COP) sway velocity during a single-leg stance on a force plate and maximum reach distances of the star excursion balance test (SEBT). The COP sway velocity increased significantly (p 〈 0.05) after general (+47%) and localized fatigue (+10%). No fatigue effects were found for the SEBT. There were no significant correlations between COP sway velocity and SEBT mean reach in any condition. The results showed that although fatigue affects static postural control, sensorimotor mechanisms responsible for regaining dynamic balance in healthy athletes seem to remain predominantly intact. Thus, our data indicate that the exclusive use of static postural sway measures might not be sufficient to allow conclusive statements regarding sensorimotor control in the noninjured athlete population.
    Keywords: Fatigue -- Health Aspects ; Team Handball -- Health Aspects ; Team Handball -- Physiological Aspects ; Athletes -- Physiological Aspects ; Athletes -- Health Aspects ; Posture -- Physiological Aspects ; Posture -- Health Aspects;
    ISSN: 1064-8011
    E-ISSN: 15334287
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  • 7
    Language: English
    In: Archives of Physical Medicine and Rehabilitation, 2011, Vol.92(6), pp.967-971
    Description: Zech A, Steib S, Freiberger E, Pfeifer K. Functional muscle power testing in young, middle-aged, and community-dwelling nonfrail and prefrail older adults. To evaluate the stair climb (SC) and sit-to-stand (STS) transfer test for functional power assessment in young, middle-aged, and community-dwelling nonfrail and prefrail older adults. Cross-sectional study. Sport science institute providing health-related exercise programs for older people. Participants (N=60; age, 22–81y) were divided into groups of young (n=15; 20–30y), middle-aged (n=16; 40–60y), nonfrail older (n=16; 〉65y), and prefrail older adults (n=13; 〉65y). Not applicable. SC and STS transfer power were measured on 2 separate occasions. Age and height correlated positively ( 〈.001) with both power measures. Multiple linear regression analysis showed that 67.9% ( ) of the variance in SC power and 31.3% ( ) of the variance in STS transfer power can be attributed to age and height. Significant age-related subgroup differences were found for SC power ( =.001). Nonfrail and prefrail older adults differed significantly in both power measures ( 〈.001). The findings indicate that SC and STS transfer power are sensitive enough to distinguish between nonfrailty and prefrailty. This suggests that both tests are relevant clinical measures in older people.
    Keywords: Older Adults ; Power ; Prefrailty ; Rehabilitation ; Sit-to-Stand Transfer ; Stair Climb ; Medicine ; Physical Therapy
    ISSN: 0003-9993
    E-ISSN: 1532-821X
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  • 8
    In: Medicine & Science in Sports & Exercise, 2016, Vol.48(5S Suppl 1), pp.586-586
    ISSN: 0195-9131
    Source: Copyright © 2013 Lippincott Williams & Wilkins. All rights reserved.〈img src=http://exlibris-pub.s3.amazonaws.com/LWW%20logo.png style="vertical-align:middle;margin-left:7px"〉
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  • 9
    Language: English
    In: Radiology, December 2018, Vol.289(3), pp.686-687
    ISSN: 00338419
    E-ISSN: 1527-1315
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  • 10
    Language: English
    In: Geochimica et Cosmochimica Acta, Feb 1, 2014, Vol.126, p.614(10)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.gca.2013.10.048 Byline: Michael Zech, Christoph Mayr, Mario Tuthorn, Katharina Leiber-Sauheitl, Bruno Glaser Abstract: The oxygen isotopic composition of cellulose is a valuable proxy in paleoclimate research. However, its application to sedimentary archives is challenging due to extraction and purification of cellulose. Here we present compound-specific [delta].sup.18O results of hemicellulose-derived sugar biomarkers determined using gas chromatography-pyrolysis-isotope ratio mass spectrometry, which is a method that overcomes the above-mentioned analytical challenges. The biomarkers were extracted from stem material of different plants (Eucalyptus globulus, Vicia faba and Brassica oleracea) grown in climate chamber experiments under different climatic conditions. The [delta].sup.18O values of arabinose and xylose range from 31.4a[degrees] to 45.9a[degrees] and from 28.7a[degrees] to 40.8a[degrees], respectively, and correlate highly significantly with each other (R =0.91, p 〈0.001). Furthermore, [delta].sup.18O.sub.hemicellulose (mean of arabinose and xylose) correlate highly significantly with [delta].sup.18O.sub.leaf water (R =0.66, p 〈0.001) and significantly with modeled [delta].sup.18O.sub.cellulose (R =0.42, p 〈0.038), as well as with relative air humidity (R =-0.79, p 〈0.001) and temperature (R =-0.66, p 〈0.001). These findings confirm that the hemicellulose-derived sugar biomarkers, like cellulose, reflect the oxygen isotopic composition of plant source water altered by climatically controlled evapotranspirative.sup.18O enrichment of leaf water. While relative air humidity controls most rigorously the evapotranspirative.sup.18O enrichment, the direct temperature effect is less important. However, temperature can indirectly exert influence via plant physiological reactions, namely by influencing the transpiration rate which affects [delta].sup.18O.sub.leaf water due to the Peclet effect. In a companion paper (Tuthorn et al., this issue) we demonstrate the applicability of the hemicellulose-derived sugar biomarker [delta].sup.18O method to soils and provide evidence from a climate transect study confirming that relative air humidity exerts the dominant control on evapotranspirative.sup.18O enrichment of leaf water. Finally, we present a conceptual model for the interpretation of [delta].sup.18O.sub.hemicellulose records and propose that a combined [delta].sup.18O.sub.hemicellulose and [delta].sup.2H.sub.n .sub.-alkane biomarker approach is promising for disentangling [delta].sup.18O.sub.precipitation variability from evapotranspirative.sup.18O enrichment variability in future paleoclimate studies. Article History: Received 1 March 2013; Accepted 21 October 2013 Article Note: (miscellaneous) Associate editor: Richard Pancost
    Keywords: Plants (Organisms) -- Analysis ; Soils -- Analysis ; Sediments (Geology) -- Analysis ; Cellulose -- Analysis ; Mass Spectrometry -- Analysis ; Proxy -- Analysis ; Monosaccharides -- Analysis ; Biological Markers -- Analysis ; Pyrolysis -- Analysis
    ISSN: 0016-7037
    Source: Cengage Learning, Inc.
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