Design and development of a field-deployable single-molecule detector (SMD) for the analysis of molecular markers

Single-molecule detection (SMD) has demonstrated some attractive benefits for many types of biomolecular analyses including enhanced processing speed by eliminating processing steps, elimination of ensemble averaging and single-molecule sensitivity. However, it's wide spread use has been hampered by the complex instrumentation required for its implementation when using fluorescence as the readout modality. We report herein a simple and compact fluorescence single-molecule instrument that is straightforward to operate and consisted of fiber optics directly coupled to a microfluidic device. The integrated fiber optics served as waveguides to deliver the laser excitation light to the sample and collecting the resulting emission, simplifying the optical requirements associated with traditional SMD instruments by eliminating the need for optical alignment and simplification of the optical train. Additionally, the use of a vertical cavity surface emitting laser and a single photon avalanche diode serving as the excitation source and photon transducer, respectively, as well as a field programmable gate array (FPGA) integrated into the processing electronics assisted in reducing the instrument footprint. This small footprint SMD platform was tested using fluorescent microspheres and single AlexaFluor 660 molecules to determine the optimal operating parameters and system performance. As a demonstration of the utility of this instrument for biomolecular analyses, molecular beacons (MBs) were designed to probe bacterial cells for the gene encoding Gram-positive species. The ability to monitor biomarkers using this simple and portable instrument will have a number of important applications, such as strain-specific detection of pathogenic bacteria or the molecular diagnosis of diseases requiring rapid turn-around-times directly at the point-of-use.close5

Charakterisierung von CAST Ruß bezüglich seiner optischen und hygroskopischen Eigenschaften

In dieser Arbeit werden Rußpartikel mit einem Combustion Aerosol STandard (CAST, Modell MiniCAST 5201c, Jing Ltd.) Generator, über einen weiten Bereich an Verbrennungseinstellungen erzeugt und anschließend charakterisiert. Als charakterisierender Parameter für die Verbrennungseinstellungen wird das C/O – Verhältnis während der Verbrennung verwendet. Die Ergebnisse zeigen bei den EC-OC (elementarer-organischer Kohlenstoff) und den BC-BrC (schwarzer-brauner Kohlenstoff) Analysen, mit einem EC-OC Analyser von Sunset Lab., bzw. einem Ulbrichtkugel - Photometer, sowie den, mit einem DMPS System, gemessenen Anzahl – Größenverteilungen, der erzeugten Verbrennungsaerosole eine deutliche Veränderung zwischen den C/O – Verhältnissen 0,301 und 0,353. Demnach wird bis zu einem C/O – Verhältnis von 0,301 stets „magerer“ Ruß mit einem hohen EC (50 % bis 95 %) bzw. BC (54 % bis 89 %) Anteil und großen (bis zu 262 nm) mittleren Durchmessern erzeugt. Ab einem C/O – Verhältnis von 0,353 wird „fetter“ Ruß mit hohem OC (> 89 %) und BrC (> 66 %) Anteil und deutlich kleineren (höchstens 147 nm) mittleren Durchmessern produziert. Nochmals deutlich kleinere mittlere Durchmesser (99 nm bzw. 67 nm) werden bei den, an den Randeinstellungen produzierten Partikeln (C/O = 0,230 und C/O > 0,602) beobachtet. Was die Zusammensetzung angeht verhält sich der Ruß der Randeinstellungen im Wesentlichen wie jener der anderen Einstellungen im jeweiligen „fetten“ bzw. „mageren“ Bereich. Der auf diese Weise produzierte Ruß wird außerdem verdünnt und mit einem Particle Into Liquid Sampler (PILS, Modell 4001, Brechtel Inc.) gesammelt. Ziel dieses Vorgehens ist es einerseits das Abscheideverhalten des PILS für frisch produzierten Ruß zu untersuchen, andererseits allgemeine Aussagen über die hygroskopischen Eigenschaften des frisch produzierten Rußes treffen zu können. Diese Ziele konnten für den BC Anteil erfüllt werden. Es zeigt sich, dass der PILS etwa 11 % des frisch produzierten BC in den flüssigen Proben sammelt. Weiters lässt sich ableiten, dass die frisch produzierten BC Partikel einen minimalen Kontaktwinkel zwischen 25° und 50°, gemäß der Fletcher Theorie, aufweisen und damit nicht als Wolkenkondensationskeime geeignet sind.In this work a Combustion Aerosol STandard (CAST, model 5201c, Jing Ltd.) generator was used to produce soot particles over a wide range of combustion settings. Afterwards the EC-OC (elemental-organic carbon, measured with a Sunset Lab. ECOC Analyser) and BC-BrC (black-brown carbon, measured with an Inetgrating Sphere Photometer) fraction, as well as the size distributions (measured with a DMPS System) for the soot produced at every setting was investigated. As a parameter to characterise the combustion settings the C/O - ratio during combustion was used. All the used analysing methods showed a sudden change of properties between the soot produced at C/O – ratios 0,301 and 0,353. For C/O – ratios smaller or equal to 0,301 soot with high EC (50 % to 95 %) and BC (54 % to 89 %) fractions and large median diameters (up to 262 nm) was produced. For C/O – ratios higher or equal to 0,353 soot with high OC (> 89 %) and BrC (> 66 %) fractions and considerably smaller median diameters (up to 147 nm) was observed. Even smaller median diameters (99 nm and 67 nm respectively) were measured for soot produced at the boundary combustion settings (C/O = 0,230 and C/O > 0,601). According to composition the soot of the boundary conditions behaves essentially like the soot of the other settings in the corresponding C/O – range. The freshly produced soot aerosols for every setting also were diluted and sampled with a Particle Into Liquid Sampler (PILS, model 4001, Brechtel Inc.). This was done to investigate the sampling efficiency of the PILS and to make some general statements about the hygroscopic properties of freshly produced soot. This could be accomplished for the freshly produced BC fractions. The PILS was found to sample about 11 % of the freshly produced BC into liquid samples. It was further derived, that the freshly produced BC particles had a maximum contact angle, according to Fletcher theory, of 25° to 50° and therefore is not likely to act as cloud condensation nuclei

Freezing on a Chip—A New Approach to Determine Heterogeneous Ice Nucleation of Micrometer-Sized Water Droplets

We are presenting a new approach to analyze the freezing behavior of aqueous droplets containing ice nucleating particles. The freezing chip consists of an etched and sputtered (15 × 15 × 1) mm gold-plated silicon or pure gold chip, enabling the formation of droplets with defined diameters between 20 and 80 µm. Several applications like an automated process control and an automated image evaluation were implemented to improve the quality of heterogeneous freezing experiments. To show the functionality of the setup, we compared freezing temperatures of aqueous droplets containing ice nucleating particles (i.e., microcline, birch pollen washing water, juniper pollen, and Snomax® solution) measured with our setup, with literature data. The ice nucleation active surface/mass site density (ns/m) of microcline, juniper pollen, and birch pollen washing water are shown to be in good agreement with literature data. Minor variations can be explained by slight differences in composition and droplet generation technique. The nm values of Snomax® differ by up to one order of magnitude at higher subzero temperatures when compared with fresh samples but are in agreement when compared with reported data of aged Snomax® samples.Fonds zur Förderung der Wissenschaftlichen Forschun

Null effect of perceived drum pattern complexity on the experience of groove

There is a broad consensus in groove research that the experience of groove, understood as a pleasurable urge to move in response to music, is related to the complexity of the rhythm. Specifically, music with medium rhythmic complexity has been found to motivate greater urge to move compared to low or high complexity music (inverted-U hypothesis). Previous studies used degrees of syncopation in music as a measure of complexity, where rhythms with more and/or stronger syncopations are considered to be more complex than rhythms with less/weaker syncopations. This study is the first to attempt the verification of the inverted-U hypothesis using forty idiomatic popular music drum pattern stimuli that are associated with perceptual complexity measures obtained in a previous study. In a listening experiment with n=179 participants, the inverted-U hypothesis could not be confirmed as complexity did not have any significant effect on listeners’ urge to move (p=.834). Results are discussed in the context of the psychological model of musical groove, which shows that more complex stimuli are heard as less regular (which negatively affects the urge to move), and as more interesting (which positively affects the urge to move). These findings show that competent drummers are capable of producing equally danceable drum patterns regardless of complexity, at least in a range of complexity that is idiomatic for this repertoire. Results also suggest that the temporal regularity of simple patterns enhances their danceability, while complex patterns invite body movement because they are more interesting for the listener