Verformungsverhalten künstlicher Makroporen unter variierenden Druck‐ und Bodenfeuchtebedingungen     

Johann Kremer  Bettina Wolf  Dietmar Matthies 《植物养料与土壤学杂志》2002,165(5):627-633

Structural deformation of artificial macropores under varying load and soil moisture In the present study, the stability and deformation behavior of artificial macropores under varying load and soil moisture levels was investigated by means of X‐ray computed tomography (CT). The results should be a reference for similar studies on soil samples from field trials. The soil tested was a well structured humic silt loam with a bulk density of 1 g cm^—3. Round‐shaped pores of vertical and 45 degree angle orientation were drilled into the samples with a plastic needle (∅︁ 5 mm). These samples were compacted in an uniaxial compression device at four different moisture levels and four pressure stages each. Stepwise CT imaging and its 3‐dimensional reconstruction enabled us to study systematically the mode and intensity of pore deformation. As a result four different deformation stages could be identified in dependence from load, soil moisture, and pore orientation. The deformation stage ”︁stable” was characterized by mostly unaffected pore dimensions and shapes. Increasing load and/or moisture content led to prominent bottle necks within the pores which was named ”︁structure deformation”. Due to the shape and size of these bottle necks it seems to be most likely that still intact aggregates were moved into the inner pore space, reducing the mean cross sectional areas. The deformation stage ”︁total deformation” appeared with further increase of load and/or moisture. The aggregated structure disappeared while the inner roughness of the pores became smoother again. This represents a viscoplastic deformation. Cross sectional areas, pore lengths, and volumes significantly decreased. The stage ”︁extinction” was finally reached at water contents around the liquid limit, where the pore structure was completely lost, at least on CT resolution level. The deformation stages could be attributed to load stages depending from pore orientation. Unexpectedly, all pores kept their originally round shape over all stages until extinction.  相似文献   

Influence of sulfur supply,ammonium nitrate ratio,and arbuscular mycorrhizal colonization on growth and composition of Chinese chive     

Henrike Perner  Dietmar Schwarz  Angelika Krumbein  Eckhard George 《Scientia Horticulturae》2011

Tissue concentrations of phytochemicals formed by Allium species may be influenced by plant nutrient supply or rhizosphere microorganism activity. To test these relations, three plant nutritional factors were varied in two experiments with Chinese chive [Allium tuberosum]: (a) increasing sulfur concentrations in the substrate, (b) two ratios of ammonium to nitrate in supply, and (c) inoculation with arbuscular mycorrhizal (AM) fungi. Shoot dry weight, nutrient composition (nitrate, N, P, S), and organosulfur compounds (measured indirectly as pyruvic acid) were determined.  相似文献   

Effect of different levels of dietary nitrogen supplementation on the relative blood urea nitrogen concentration of beef cows     

Tshuma  Takula  Fosgate  Geoffrey Theodore  Hamman  Robyn  Holm  Dietmar Erik 《Tropical animal health and production》2019,51(7):1883-1891

The objective of this study was to determine if individual beef cows in a herd have an inherent ability to maintain their blood urea nitrogen (BUN) concentration when exposed to different levels of dietary nitrogen supplementation. Ten Hereford and 12 Nguni cows, aged between 2 and 16 years, were utilized in two crossover experiments. In the first experiment, cows were exposed to two diets: a balanced diet with a crude protein (CP) level of 7.9% and a modified diet with a CP level of 14%, formulated by adding 20 kg of feed grade urea per ton of the balanced diet. At the end of the first crossover experiment, cows received the balanced diet for 1 week. The second component utilized the same cows wherein they were fed the balanced diet in addition to another modified diet containing only 4.4% CP. Blood urea nitrogen concentration was measured 22 times (twice weekly) from each cow during both components of the study. A linear mixed-effects model was used to assess whether baseline BUN concentration (measured 1 week before onset of the study) was predictive of subsequent BUN concentration in individual cows. Breed, cow age, body condition score, and body mass were also evaluated for their effects on BUN concentrations. Albumin, beta hydroxybutyric acid (BHBA), glucose, and total serum protein (TSP) were compared between diets within each breed. Baseline BUN concentration was a significant predictor of subsequent BUN concentration in individual cows (P = 0.004) when evaluated over both components of the study. Breed (P = 0.033), the preceding diet (P < 0.001), current diet (P < 0.001), and the week during which sampling was performed (P < 0.001) were also associated with BUN concentration. Results suggest that beef cattle (within a herd) have an inherent ability to maintain their BUN concentration despite fluctuations in levels of available dietary nitrogen.

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Development of a highly sensitive and specific enzyme-linked immunosorbent assay for detection of Sudan I in food samples   总被引：1，自引：0，他引：1  

Han D  Yu M  Knopp D  Niessner R  Wu M  Deng A 《Journal of agricultural and food chemistry》2007,55(16):6424-6430

A highly selective and sensitive indirect competitive enzyme-linked immunosorbent assay (ELISA) for Sudan I was developed. Two hapten derivatives with different lengths of carboxylic spacer at the azo-bound para-position were synthesized and coupled to carrier proteins. The hapten-bovine serum albumin (BSA) conjugates were used as immunogens, while the hapten-ovalbumin (OA) conjugates were applied as coating antigens. The antisera which were obtained from four immunized rabbits were characterized in terms of sensitivity and specificity. At optimal experimental conditions it was found that IC50 and LOD values of seven pairs based on four antisera and two coating antigens were in the range of 0.3-2 ng/mL and 0.02-0.1 ng/mL, respectively. The most sensitive ELISA could be established with Sudan I-propionic acid-OA coating antigen and the antiserum which was obtained with the corresponding immunogen. The cross-reactivity values of the four antisera with Sudan II, III, and IV was estimated with 0.1-14.3%. No cross-reactivity was found with six edible colorants Sunset yellow, Amarant, Kermes, Indigotin, Bright blue and Lemon yellow, indicating high specificity for Sudan I. Six food samples were fortified with Sudan I and extracted by simple sample preparation. The methanolic extracts after dilution with methanol:water (5:95, v/v) were analyzed by the developed ELISA. Assay precision and accuracy was estimated by determination of three replicates. Acceptable recovery rates of 92.5-114% and intra-assay coefficients of variation of 5.9-24.8% were obtained. The data were validated by conventional HPLC method. As revealed, both methods were highly correlated (r = 0.9851, n = 7), demonstrating the applicability of the developed ELISA for Sudan I analysis in food samples.  相似文献   

Biomass estimations in forests of different disturbance history in the Atlantic Forest of Rio de Janeiro,Brazil     

André Lindner  Dietmar Sattler 《New Forests》2012,43(3):287-301

Tropical forests are large reservoirs of biomass and there is a need for information on existing carbon stocks in these ecosystems and especially the effects of logging on these stocks. Reliable estimates of aboveground biomass stocks within the Atlantic Forest are rarely available. Past human disturbance is an important factor affecting forest structure variation and biomass accumulation among tropical forest ecosystems. To support the efforts of improving the quality of estimations of the current and future biomass carbon storage capacity of this disturbed forest region we tested a non-experimental small scale approach to compare the aboveground tree biomass (AGB) of forest sites. Three sites with known disturbance histories have been investigated: complete cut down, selective logging and conservation since 70 years. The woody plant community (dbh ≥ 10 cm) was censused and canopy openness in conjunction with leaf area index has been obtained by hemispherical photographs at each site. Estimates of aboveground tree biomass have been carried out using an allometric equation for moist tropical forests already applied for the study area. Additionally, a FAO standard equation has been employed for crosschecking our results. We identified significant differences in recent AGB of the three compared forest sites. With 313 (±48 Mg ha⁻¹) the highest AGB-values have been found in the preserved forest area within a National Park, followed by 297 (±83) Mg ha⁻¹ at the former clear cut site. Lowest AGB has been calculated for the area with past selective logging: 204 (±38) Mg ha⁻¹. Values calculated with the FAO standard equation showed the same trend but at a lower AGB level. Our results based an a small scale approach suggest that biomass productivity can recover in a forest which was completely cleared 60 years ago to reach AGB values up to a level that almost represents the situation in a preserved forest. Selective logging may slow down AGB accumulation and the effect is measurable after several decades.  相似文献   

Severe Streptococcus infection in spotted hyenas in the Ngorongoro Crater, Tanzania     

Höner OP  Wachter B  Speck S  Wibbelt G  Ludwig A  Fyumagwa RD  Wohlsein P  Lieckfeldt D  Hofer H  East ML 《Veterinary microbiology》2006,115(1-3):223-228

In a population of spotted hyenas (Crocuta crocuta) monitored between 1996 and 2005 in the Ngorongoro Crater, Tanzania, 16 individuals from five of eight social groups displayed clinical signs of an infection, including severe unilateral swelling of the head followed by abscess formation at the mandibular angle, respiratory distress, mild ataxia, and lethargy. Two (12.5%) of these 16 individuals died within days of developing signs. Clinical signs in hyenas were first noted in 2001, and most cases occurred between September 2002 and February 2003, suggesting an outbreak of infection during this period. Histopathological examination of internal organs from one hyena that died with signs revealed morphological changes consistent with severe bacterial infection. Phenotypic examination and phylogenetic analysis of the 16S rRNA gene of the causative agent of infection revealed a Lancefield group C Streptococcus with a high level of homology to S. equi subsp. ruminatorum, a subspecies of S. equi recently described in domestic sheep (Ovis aries) and goats (Capra hircus) with mastitis in Spain. Strains similar to this bacterium were also isolated from two hyenas without obvious clinical signs, suggesting that hyenas may be 'carriers' of this bacterium, and from a sympatric Burchell's zebra (Equus burchelli), a herbivore species often consumed by hyenas. To our knowledge this is the first report of a Streptococcus infection in these two wildlife species. The high genetic similarity between the hyena and zebra isolates indicates that inter-specific transmission may occur, possibly when hyenas consume infected zebra carcasses.  相似文献   

NEPTUN oder „Wie oft wird gespritzt?“     

Dietmar Roßberg 《Gesunde Pflanzen》2007,59(2):55-65

In 1999/2000 the ?Netzwerk zur Ermittlung der Pflanzenschutzmittelanwendung in unterschiedlichen, landwirtschaftlich relevanten Naturräumen Deutschlands (NEPTUN)“ was launched to collect detailed and close-to-practice data on the actual use of chemical pesticides in agriculture. The data were collected from selected farms on a voluntary basis. They have been stored anonymously, in relation to natural spaces and covered any chemical plant protection treatment including the application of growth regulators. This requires close co-operation of the authorities of the Federal Republic of Germany and of the Federal Bundesländer and the relevant professional associations. The project has been funded by the principal, the Federal Ministry of Nutrition, Agriculture and Consumer Protection. Funding depends on the number of provided records. As all data are collected and handled at the Federal Biological Research Centre for Agriculture and Forestry, they have a unique structure. This is necessary for analyses and extrapolation. At the same time a number of plausibility tests verify the individual data. Data analyses refer to the defined survey regions or the total area of the Federal Republic of Germany. The program calculates the ‘treatment frequency’ and the ‘application index’ indicators. Furthermore, it gives a ranking of applied active ingredients with respect to crop and groups of active ingredients. Method and results of the surveys are detailed in the final reports. Furthermore, the final reports contain an expert evaluation of the calculated indicators.  相似文献   

Detectability of degradable organic matter in agricultural soils by thermogravimetry     

David Tokarski  Jana &#x;ime kov  Ji&#x;í Ku erík  Karsten Kalbitz  Michael Scott Demyan  Ines Merbach  Dietmar Barkusky  Joerg Ruehlmann  Christian Siewert 《植物养料与土壤学杂志》2019,182(5):729-740

Sustainable agricultural land use requires an assessment of degradable soil organic matter (SOM) because of its key function for soil fertility and plant nutrition. Such an assessment for practical land use should consider transformation processes of SOM and its sources of different origin. In this study, we combined a 120‐day incubation experiment with thermal decay dynamics of agricultural soils altered by added organic amendments. The aim was to determine the abilities and limits of thermal analysis as a rapid approach revealing differences in the degradability of SOM. The carried out experiments based on two independent sampling sets. The first sample set consisted of soil samples taken from non‐fertilized plots of three German long‐term agricultural field experiments (LTAEs), then artificially mixed with straw, farmyard manure, sheep faeces, and charcoal equal to 60 Mg ha^?1 under laboratory conditions. The second sample set based on soil samples of different treatments (e.g., crop type, fertilization, cultivation) in LTAEs at Bad Lauchstädt and Müncheberg, Germany. Before and after the incubation experiment, thermal mass losses (TML) at selected temperatures were determined by thermogravimetry indicating the degradability of organic amendments mixed in soils. The results confirmed different microbial degradability of organic amendments and SOM under laboratory conditions. Thermal decay dynamics revealed incubation‐induced changes in the artificial soil mixtures primarily at TML around 300°C in the case of applied straw and sheep faeces, whereas farmyard manure showed mainly changes in TML around 450°C. Charcoal did not show significant degradation during incubation, which was confirmed by TML. Detailed analyses of the artificial soil mixtures revealed close correlations between CO₂‐C evolution during incubation and changes in TML at 300°C with R² > 0.96. Results of the soils from LTAEs showed similar incubation‐induced changes in thermal decay dynamics for fresh plant residues and farmyard manure. We conclude that the practical assessment of SOM could be facilitated by thermal decay dynamics if modified sample preparation and evaluation algorithms are used beyond traditional peak analysis.  相似文献   

Bestimmung von Insektizid-Rückständen und Prüfung von Dauerbelägen     

Dr. Dietmar Römer 《Journal of pest science》1960,33(9):138-140

Ohne Zusammenfassung® eingetragenes Warenzeichen.  相似文献   

Cryptoxanthin structural isomers in oranges, orange juice, and other fruits     

Schlatterer J  Breithaupt DE 《Journal of agricultural and food chemistry》2005,53(16):6355-6361

Citrus fruits contain a wide range of bioactive compounds. Their carotenoid fraction is inter alia dominated by structural cryptoxanthin isomers as beta-cryptoxanthin and zeinoxanthin. Both xanthophylls were identified in saponified citrus fruit extracts by comparison to reference compounds extracted from corn and by their typical fragmentation pattern in LC-(APCI)MS analyses. alpha-Cryptoxanthin, another structural cryptoxanthin isomer usually found in carrot leaves, was not identified in the citrus fruits studied. Cryptoxanthin concentrations of direct orange juices (D) and reconstituted juices (C) were compared. Although the respective mean values [beta-cryptoxanthin, 62 (C) versus 110 microg/100 g (D); zeinoxanthin, 22 (C) versus 37 microg/100 g (D)] were statistically distinguishable (P < 0.05%), a doubtless classification is not possible because the concentration ranges overlap. To identify esters of structural cryptoxanthin isomers in native orange juice extracts, four saturated acyl esters were synthesized. LC-(APCI)MS studies revealed for the first time that the dominant acylation partners of both xanthophylls were C12:0, C14:0, and C16:0 in nearly equal amounts of roughly one-third, whereas C10:0 and C18:1 were present at lower extents of 5-14%; other acylation partners were not identified. The presented method is appropriate to gain deeper insight into the pattern of structural cryptoxanthin isomers of citrus fruits. Knowledge of acylated cryptoxanthin isomers may be important in the evaluation of the bioavailability of individual esters in future human digestion studies.  相似文献