Advances in catalysis for fuel cells

Imperial Users onl

Screening Revolution: Cinema as an Alternative Public Space during the Years of Lead (1969 - 1994)

1969 to 1988 was a period of social and political unrest in Italy known as the Years of Lead. Within this political foment, leftist directors produced films that dealt with topics that were of concern to the Left such as the condition of factory workers and police corruption. This thesis explores the role of cinema within the public sphere, whether it acted as an alternative space, and whether its role changed over time. Influenced by neo- Habermasian theory, I hypothesize that cinema served as an alternative public space in which directors critiqued the environment which drove students and workers to the streets and as a political device to promulgate leftist ideas often through weaving them into poignant narratives. I explore this hypothesis and cinema’s changing role over a period of twenty-five years from 1969 until 1994 by looking at particular films and directors from that period

Oxytetracycline at Environmental Interfaces Studied by Second Harmonic Generation

Patrick Hayes - Dept. of Chemistry, Northwestern UniversityOpe

Converse Magnetoelectric Resonators for Biomagnetic Field Sensing

Contact-less biomagnetic sensing constitutes the next frontier for advanced healthcare, bringing novel diagnostic abilities using multichannel magnetocardiography (MCG) and magnetoencephalography (MEG) either as a single source of information for rapid patient screening or in combination with established methods such as electrocardiography (ECG) and electroencephalography (EEG) as a source for additional patient information. The combination of established electrical with magnetic patient information potentially leads to novel tools for deep knowledge generation towards pathologies and early prevention of such. The main obstacle towards biomagnetic diagnosis using magnetic imaging techniques is the lack of easy applicable sensor technology which offers extremely low magnetic noise floors; realtime MCG measurements demand for lower than 10 pT/sqrt(Hz), reaching below 100 fT/sqrt(Hz) enables even MEG signal acquisition. Such extremely minute amplitudes that are six to seven orders lower than earth's permanent magnetic field, demand lowest noise sensor technology as the low frequency signal regime below about 1 kHz is strongly affected by omnipresent 1/f-noise. Magnetoelectric (ME) thin film composites consisting of a sputtered piezoelectric (PE) and an amorphous magnetostrictive (MS) layer are usually employed for measurements of magnetic fields passively, i.e. an AC magnetic field directly generates an ME voltage by mechanical coupling of the MS deformation to the PE phase. In order to achieve high field sensitivities, a magnetic bias field is required to operate at the maximum piezomagnetic coefficient of the MS phase. Additionally using mechanical resonances further enhances this direct ME effect size. Despite being able to directly detect very small field amplitudes on the order of 1 pT/sqrt(Hz) for magnetic fields of a frequency exactly matching mechanical resonances comes at the expense of available signal bandwidth, because of rather high resonator quality factors. Strong 1/f noise prevalent in the low frequency regime, makes DC or low frequency magnetic fields tedious to record in that regime using direct ME detection scheme. In the presented work the PE phase is actively excited, thus exploiting the converse ME effect, remedying the shortcomings of the direct effect. ME composites are demonstrated for use as precision sensors, capable of magnetic signal detection in the low frequency, low amplitude biomagnetic regime. The combination of the converse ME effect with high frequency acoustic resonances leads to high piezoelectric stresses generated within the composite, leading to large inverse magnetostriction and thus high sensitivity. A limit of detection (LOD) of 70 pT/sqrt(Hz) at 10 Hz is obtained with composites based on amorphous films of Iron-Cobalt-Silicon-Boron (FeCoSiB). Exploiting advanced magnetoelectric composites based on exchange biased FeCoSiB films (EB-FeCoSiB) LOD values reaching down to 17 pT/sqrt(Hz) at 10 Hz are demonstrated. A trial recording a healthy subjects human MCG signal using an advanced ME composite demonstrates the practical feasibility of biomagnetic measurements and paves the way for routine, realtime biomagnetic measurements in the future.Kontaktlose biomagnetische Diagnostik stellt die nächste Generation von Patientenmonitoring und bildgebender Diagnostik dar, sie ist in der Lage einen schnellen, kontaktlosen Überblick der Vitalfunktionen zu liefern. In Kombination mit etablierten Methoden wie Elektrokardiografie (EKG) und Elektroenzephalografie (EEG) entsteht ein zusätzliches Werkzeug zur Erlangung tieferer Informationen über Pathogenesen und ermöglichen somit eine frühzeitige Erkennung solcher. Die größte technische Hürde der biomagnetischen Diagnose stellt die Entwicklung einer anwenderfreundlichen, wartungsarmen Sensortechnologie dar. Diese Technologie muss über ein extrem niedriges magnetisches Rauschen von kleiner als 10 pT/sqrt(Hz) für Echtzeit Magnetokardiografie (MKG) und bis unter 100 fT/sqrt(Hz) für Magnetoenzephalografie (MEG) verfügen. Derartige Feldstärken von biomagnetischem Niveau sind etwa sechs bis sieben Größenordnungen geringer als das statische Erdmagnetfeld und dabei ebenfalls stets niederfrequent, unterhalb etwa 1 kHz. Damit liegen die relevanten Magnetfelder im Bereich des omnipräsenten 1/f-Rauschens. Magnetoelektrische Dünnschicht-Komposite werden üblicherweise passiv betrieben, indem ein magnetisches Wechselfeld direkt zu einer proportionalen ME-Spannung führt. Dies geschieht mittels magnetostriktiver Dehnung welche durch mechanische Kopplung auf ein Piezoelektrikum übertragen wird und dort eine elektrische Spannung über den direkten piezoelektrischen Effekt erzeugt. Um den größtmöglichen piezomagnetischen Koeffizienten zu erhalten, kommt zusätzlich ein statisches magnetisches Haltefeld zum Einsatz. Durch die Ausnutzung mechanischer Resonanzen wird die Oszillation verstärkt, diese Verstärkung führt in gleichem Maße zu einer Verstärkung des ME-Effekts. Auf diese Weise ist es möglich, magnetische Detektionsgrenzen von etwa 1 pT/sqrt(Hz) zu erreichen, weit im erforderlichen Bereich für Echtzeit MKG Messungen. Diese direkte Ausnutzung mechanischer Resonanzen von hohem Gütefaktor, bringt den wesentlichen Nachteil, dass die Bandbreite des ME Oszillators auf wenige Herz beschränkt ist, welches einer praktischen, breitbandigen Signalerfassung entgegen steht. In dieser Arbeit wird die piezoelektrische Materialphase direkt elektrisch angeregt, es wird der inverse ME-Effekt ausgenutzt. Dieser inverse ME Effekt stellt sich als vorteilhaft im Bezug auf den direkten ME-Effekt heraus, da eine rauscharme Operation ermöglicht wird. Magnetoelektrische Dünnschicht-Komposite werden als Präzisionssensoren zur Detektion von niederfrequenten magnetischen Kleinstsignalen untersucht. Die Kombination aus inversem ME-Effekt und der Ausnutzung hochfrequenter mechanischer Oszillationen führt zu starken mechanischen Verspannungen in der magnetostriktiven Phase und dadurch zu hoher Empfindlichkeit des Sensor-Komposites. Eine Detektionsgrenze von 70 pT/sqrt(Hz) bei einer Frequenz von 10 Hz wird unter Verwendung von magnetostriktiven Einfachlagen erreicht. Die Verwendung fortgeschrittener Mehrlagen-Materialsysteme führt zu einer weiteren Verringerung der Detektionsgrenze auf 17 pT/sqrt(Hz) bei 10 Hz. Schließlich wird in einer Feldstudie am gesunden Probanden eine Machbarkeit zur Detektion humaner MKG Signale gezeigt

Organic barley producers' desired qualities for crop improvement

Barley fits well into many different organic farming systems. It can be grown as either a winter or spring annual crop in many temperate regions. Barley can be used for food, malting, or animal feed, providing growers with diverse marketing opportunities. Despite its advantages, many organic farmers in the USA have not adopted barley as a regular crop in their rotation. Researchers surveyed organic barley producers to discover what they considered to be the main obstacles to growing barley. The primary obstacles identified were limited markets and price. Breeding and development of high-quality barley suitable for organic systems and specialty markets may be a way to expand markets and secure a better price. Farmers identified yield as the most important agronomic trait of interest, but other traits such as nutritional quality were also highly ranked. Naked (hull-less) barley bred for multi-use quality is a possible alternative that allows organic farmers to sell into multiple markets. Most respondents expressed interest in the development of such varieties suitable for organic farming conditions. The researchers conducted follow-up interviews to obtain detailed information on how barley is used in organic farming systems, production practices, costs of production, and what traits farmers would like to see breeders focus on

Improving Barley for Organic Producers: What Do Organic Producers Want?

Researchers surveyed organic barley producers in order to find out how many acres they are growing, what varieties they grow, what markets they are growing barley for, whether they receive a price premium for organic barley, whether they are growing or would be interested in growing multi-use naked barley, what production challenges they face, and what traits they would like to see improved

A quantitative study of the water quality and plankton of Upper Blue Lake, Lower Blue Lake, and the Oaks Arm of Clear Lake in Lake County, California

This study was undertaken to examine any possible associations between the measurements of water quality and lake conditions, and the quantity and composition of plankton present in Upper Blue Lake, Lower Blue Lake, and the Oaks Arm of Clear Lake during the sampling period. A secondary objective of this study was to provide a record of these measurements. These measurements, when taken collectively, are important indicators of the trophic state or nutrient condition of the waters of the three lakes from February through October 1972