Sökresultat

Filtyp

Din sökning på "*" gav 529856 sökträffar

On-line solid-phase extraction in liquid chromatography using restricted access pre-columns for the analysis of s-triazines in humic-containing waters

A coupled-column liquid chromatographic system using solid phase extraction pre-columns for the seven chlorotriazines, atrazine, desethylatrazine, desisopropylatrazine (DIA), propazine, simazine, desethylterbuthylazine and terbuthylazine, using photodiode-array detection (PDAD) was developed. Restricted access (RA), was investigated as a pre- column material, making use of non-adsorptive size excl

Tyrosinase graphite-epoxy based composite electrodes for detection of phenols

The characterization and analytical performance of a tyrosinase graphite-epoxy electrode for the detection of phenolic compounds are described. The biocomposite configuration is based on the entrapment of commercially available tyrosinase in a graphite-epoxy matrix, and the mixing of the resulting conductive epoxy resin with a hardener. The enzyme electrode is mounted as a working electrode in an

Genetic signals of high-altitude adaptation in amphibians : A comparative transcriptome analysis

Background: High-altitude adaptation provides an excellent system for studying how organisms cope with multiple environmental stressors and interacting genetic modifications. To explore the genetic basis of high-altitude adaptation in poikilothermic animals, we acquired transcriptome sequences from a high-altitude population and a low-altitude population of the Asiatic toad (Bufo gargarizans). Tra

Infrastructures as analytical framework for mapping research evaluation landscapes and practices

This paper suggests an infrastructure perspective, as suggested by Star and Bowker (2006), as an analytical framework for studying the research evaluation landscape. An infrastructure is suggested to be understood, not as a concrete technology, but as a system of contextual factors including ‘Actors/Stakeholders’, ‘Technical systems’, and ‘Evaluation practices’. How the framework can be operationa

Infrastructures as an analytical framework for understanding research evaluation systems

When trying to map the bibliometrics based ‘research evaluation landscape’ in terms of for instance methods, technical systems and stakeholders; the complexities soon become obvious. Different methods are used at different national and local levels; there is a great variation of systems used for gathering, organizing, and analyzing data; and a multitude of stakeholders, many of which taking on a v

Historical change and drivers of insect pest abundances in red clover seed production

Plant-feeding insects reduce yields substantially in all major crops despite considerable crop protection efforts. A lack of long-term monitoring data and insufficient ecological knowledge of pest insects limit our possibilities to characterize drivers of change in their abundances. We demonstrate how a suite of complementary methods and data sources can be used to analyse historical shifts in pes

Scientific publications as boundary objects: theorising the intersection of classification and research evaluation

Introduction. When using bibliometrics for research evaluation, the classification of research fields is an issue of great importance. The purpose of this paper is to outline a brief theoretical framework for analysing the role of classification in research evaluation practices.Theory. Taking departure in the concept of ‘boundary objects’ we develop a theoretical framework for analyses of how scie

A 2.7-GHz multi-level PWM carrier-bursting RF transmitter

Carrier-bursting is an attractive RF transmitter concept to achieve high efficiency. The power amplifier (PA) itself either operates at its peak efficiency or is turned off. Another efficiency-enhancing approach is the Doherty concept, where the main PA reaches its peak efficiency already in back-off and the peak PA contributes at high input levels to reach the desired output power. In this work,

Protein phosphorylation/dephosphorylation in the inner membrane of potato tuber mitochondria

Inside-out inner mitochondrial membranes free of matrix proteins were isolated from purified potato tuber (Solanum tuberosum L.) mitochondria and incubated with [γ-32P]ATP. Proteins were separated by SDS-PAGE and visualized by autoradiography. Phosphorylation of inner membrane proteins, including ATPase subunits, was strongly inhibited by the phosphoprotein phosphatase inhibitor NaF. We propose th

Towards in-cylinder chemical species tomography on large-bore IC engines with pre-chamber

A feasibility study is presented and the achieved key design milestones towards the first application of Chemical Species Tomography by Near-IR Absorption Tomography on a heavy duty, large-bore marine engine to visualise relative mixture strength are described. The engine is equipped with pre-chamber ignition and operates using Liquefied Natural Gas with >88.9% methane content. Operation of the en

Microspectroscopic infrared specular reflection studies of multi-component urinary stones at beamline D7 at the MAX IV laboratory, Lund Sweden

At the beamline D7 at the MAX III ring at the MAX IV laboratory we have a setup for infrared microspectroscopy which is usable from 30 to 10000 cm-1. In this project specular reflection infrared microspectroscopy was used for chemical imaging of cross-sectioned urinary stones. to determine their chemical composition and morphology simultaneously. Absorption spectral bands were recovered from refle

Understanding charge carrier dynamics in solar cell materials using time resolved terahertz spectroscopy

The need for developing highly efficient solar cell devices have never been so pressing until recently when the urgency of using renewable energy sources becomes more evident. There are several promising technologies being explored by many groups with the sole purpose of optimizing harvesting sunlight and converting it to useful electricity. These include, but not limited to, dye- and quantum dot-

Assessing complexity in learning outcomes – a comparison between the SOLO taxonomy and the model of hierarchical complexity

An important aspect of higher education is to educate students who can manage complex relationships and solve complex problems. Teachers need to be able to evaluate course content with regard to complexity, as well as evaluate students’ ability to assimilate complex content and express it in the form of a learning outcome. One model for evaluating complexity is the Structure of Observed Learning O

A BiCMOS single ended multiband RF-amplifier and mixer with DC-offset and second order distortion suppression

Direct conversion receivers are widely used for full duplex mobile radio communication systems. This paper describes a novel SAW-less single-ended RF amplifier connected to a single-ended mixer with a feedback loop that suppresses the second-order distortion from TX cross modulation of the LO-leakage as well as DC-offset at the mixer output. In Monte Carlo simulations the design achieves +47 dBm m

Osannolika händelser och den svenska realistiska romanen : Ett estetiskt och existentiellt bekymmer

Avhandlingens ämne är osannolika händelser i den realistiska romanen. Den övergripande idén är att realismen utmärks av att osannolika händelser hanteras utifrån ett dubbelt perspektiv: både som ett existentiellt och ett estetiskt bekymmer. Som ett existentiellt bekymmer representerar den narrativa fiktionsberättelsens osannolika händelser den ständigt närvarande möjligheten att en oförutsägbar ocThis thesis deals with improbable events in the realistic novel. The overarchingidea is that realism is distinguished by dealing with improbable events on thebasis of a double perspective: both as an existential and as an aesthetic problem.As an existential problem the improbable events of narrative fiction representthe constantly present possibility of an unexpected and unforeseen event suddenly

Native milk fat globule size and its influence on whipping properties

The objective of this study was to investigate the influence of native milk fat globule size on the aeration of high fat dairy products with regard to maximum firmness time, gas inclusion and foam stability. The results showed that whipping time to maximum firmness was inversely proportional to mean fat globule size for both unhomogenised and slightly homogenised (2 MPa) creams. Additionally, incr