Druckverbreiterung von Spektrallinien

In dieser Arbeit wurde die Druckverbreiterung einer Spektrallinie von Formaldehyd gemessen. Ziel war es, zu klären, welche Faktoren die Druckverbreiterung begünsti-gen. Deshalb wurde hier die Verbreiterung einer Formaldehydlinie bei ansteigendem Eigendruck und die Verbreiterung bei konstantem Formaldehyddruck und ansteigen-dem Druck eines Fremdgases bestimmt. Die verwendete Linie war ein 414 ?515 -Übergang. Folgende Ergebnisse lassen sich feststellen. §Eher sterische Gründe als die Masse begünstigen die Druckverbreiterung. §Dipolmomente beeinflussen die Druckverbreiterung am stärksten. Anhand der gemessenen Gase konnte folgende Reihenfolge der gemessenen Gase in Punkto Wechselwirkung getroffen werden: Edelgase < O2< D2< SF6 ? CH4 ? CF4 < N2 < NO< HCl < H2 < N2O <C2H4 < CO2 < C2H2 < CH3F < CHF3 < CH2F

Biochemische Analyse der Kollagenstruktur residualen Dentins nach chemo-mechanischer Kariestherapie

Chemo-mechanische Verfahren zur Kariesentfernung, wie die Anwendung von CarisolvTM, werden als schonende Alternativen zur konventionellen Anwendung des Bohrers diskutiert. Es wird angenommen, dass CarisolvTM dabei hilft, das denaturierte Kollagen in der kariösen Läsion aufzulösen. Es wird darüber hinaus vermutet, dass das intakte Kollagen innerhalb der Läsion nach diesem Verfahren erhalten werden kann. Dieses Dentin hätte die Möglichkeit sich zu remineralisieren. Dies stünde im Gegensatz zu der aggressiveren traditionellen Kariesentfernung mit rotierenen Instrumenten, die sich vornehmlich an der Härte des Dentins am Kavitätenboden orientiert. Es war deshalb das Ziel der vorliegenden Untersuchung, die Kollagenstruktur des Dentins am Kavitätenboden nach chemo-mechanischer Kariesbehandlung mit CarisolvTM biochemisch zu analysieren. Bei jeweils 35 Zähnen der permanenten und der primären Dentition wurde die Dentinkaries chemo-mechanisch mittels CarisolvTM entsprechend den Herstellerangaben mit speziellen Handinstrumenten entfernt. Anschließend wurde eine dünne Schicht Dentin am Kavitätenboden niedertourig mit einem Rosenbohrer exkaviert. Die so gewonnenen Dentinproben wurden zunächst mit 0,5 M EDTA demineralisiert, dann gegen 0,5 % Essigsäure dialysiert und anschließend durch Ultrafiltration von intakten Kollagenmolekülen befreit. Das Ultrafiltrat wurde lyophilisiert und der Bestimmung von Kollagen-Quervernetzungskomponenten mittels HPLC zugeführt. Als Kontrollen dienten einerseits Proben gesunden Dentins aus 60 kariesfreien Zähnen, andererseits das mittels CarisolvTM entfernte kariöse Dentin. Während im Ultrafiltrat gesunden Dentins die Kollagen-Quervernetzungskomponenten lediglich in einem Anteil von 0,2 % der gesamten Dentinprobe gefunden wurden, lag dieser Anteil im residualen Dentin von permanenten Zähnen bei 34 % und von Milchzähnen bei 64 %. Hingegen fanden sich die Kollagen-Crosslinks des kariösen chemo-mechanisch entfernten Dentins erwartungsgemäß zu annähernd 100 % im Ultrafiltrat. Die Ergebnisse dieser In-vitro-Untersuchung haben gezeigt, dass die Kollagenstruktur des residualen Dentins am Kavitätenboden nach chemo-mechanischer Kariesbehandlung nicht derjenigen gesunden Dentins entsprach. Vielmehr war in erhöhtem Maß denaturiertes Kollagen zu finden. Somit muß die Möglichkeit einer selektiven und vollständigen Enfernung denaturierten Kollagens aus der Dentinkaries mit dem untersuchten chemo-mechanischen Verfahren in Frage gestellt werden

Economic analysis of tropical forages in livestock systems in the eastern plains of Colombia

70% of the Colombian livestock production are characterized by extensive production systems, which usually show low productivity levels, low land use efficiency and often lack environmental sustainability. This is related to native or naturalized grasses and degraded pastures that generate limited forage supply, both in biomass and quality, especially in the dry season. The International Center for Tropical Agriculture (CIAT) and its partners are working on the selection and development of improved forages able to adapt to diverse soil and climatic conditions of the lowland tropics, while increasing productivity levels and reducing the environmental impact of livestock production. However, the establishment of these new forage technologies implies higher investment and management costs for the producer, which could limit their adoption. This paper evaluates the financial viability of the implementation of new forage technologies, in this case of improved pastures and scattered trees in livestock systems, and compares them to the traditional production system with native/naturalized pastures. The developed model is based on a cash flow analysis and a Monte Carlo simulation, and includes uncertainty factors in the variables identified as critical (e.g., meat price, productivity). Research took place in 2015 in the Casanare Department in the Eastern Plains of Colombia. The results indicate that investment in improved pastures is profitable with an incremental net present value (NPV) of US$ 45 and an internal rate of return of 18%. The system in association with scattered trees was not profitable due to the high initial investment costs and time expectations for achieving improvements in production parameters. Both evaluated alternatives were only evaluated for livestock income, not taking into account additional income that might arise from the trees (e.g., fruits, wood). The feasibility of investment is highly sensitive to changes in the selling prices of the meat and expected returns. The technologies evaluated in this study showed to be an alternative to improve production efficiency and profitability of livestock farms. However, strategies and / or incentives need to be developed that aim at reducing the high initial costs of systems in association with scattered trees

Estimating Atrazine Leaching in the Midwest

Data from seven Management Systems Evaluation Areas (MSEM) were used to test the sensitivity of a leaching model, PRZM-2, to a variety of hydrologic settings common in the Midwest. Atrazine leaching was simulated because the use of atrazine was prevalent in the MSEA studies and it frequently occurs in the region\u27s groundwater. Results of long-term simulations using regional and generalized input parameters produced ranks of leaching potential similar to those based on measurements. Short-term simulations used site-specific soil and chemical coefficients

Modifications of the metabolic pathways of lipid and triacylglycerol production in microalgae

Microalgae have presented themselves as a strong candidate to replace diminishing oil reserves as a source of lipids for biofuels. Here we describe successful modifications of terrestrial plant lipid content which increase overall lipid production or shift the balance of lipid production towards lipid varieties more useful for biofuel production. Our discussion ranges from the biosynthetic pathways and rate limiting steps of triacylglycerol formation to enzymes required for the formation of triacylglycerol containing exotic lipids. Secondarily, we discuss techniques for genetic engineering and modification of various microalgae which can be combined with insights gained from research in higher plants to aid in the creation of production strains of microalgae

Cattle production under grazing with improved forages in the lowland tropics of Colombia

* Increase in global population and changes in people’s lifestyles and diets generate high demand for animal protein sources. * Cattle production systems in Colombia are mostly extensive and inefficient. * The International Center for Tropical Agriculture (CIAT) works on sustainable intensification (SI) of livestock systems through improving their efficiency and productivity while mitigating negative environmental effects (e.g. deforestation, greenhouse gas emissions). * SI of livestock systems can be achieved through selection and breeding and subsequent adoption of improved forages, which can either be used as stand-alone technology or be part of a (e.g. silvopastoral) system. * Silvopastoral systems (SPS) have shown excellent results in terms of higher biomass production, higher animal stocking rates, better nutritional quality and positive environmental effects

The extent and economic significance of cultivated forage crops in developing countries

Forage grasses and legumes are the principal source of nutrition for most ruminant livestock in developing countries. Raising yields of forage crops can increase the availability and affordability of livestock products as well as reduce pressure on increasingly scarce land resources by enabling greater herd densities on existing pasture. However, the economic significance of cultivated forage crops in developing countries is not well-understood. We provide estimates of the present area and production value of cultivated forage crops as well as review evidence on the extent of adoption of CGIAR- derived improved varieties of cultivated forage species and their economic impact in developing countries. There are at least 159 million hectares under cultivated forage crops producing yield worth around $63 billion per year (at 2014-2016 prices). Latin America accounts for about 85$5.8 billion/year