bluuebunny/crossref_metadata_2025 huggingface dataset:
Snowmelt energy balance in a burned forest plot, Crowsnest Pass, Alberta, Canada
Authors: Burles Katie , Boon Sarah
Published: March 2011

Forested headwater basins in western North America are subject to major change from natural and anthropogenic disturbance, including wildfire, insect infestation, disease, and forest harvesting. These changes have subsequent impacts on sub‐canopy snow processes, particularly snow accumulation and melt, with cascading effects on downstream systems. We apply a simple, process‐based point energy balance model to quantify differences in energy balance characteristics between a burned and a control plot. In the burned plot, more snow accumulated on the ground surface, there was more energy available for snowmelt, the snow melted more rapidly, and complete snowpack removal occurred sooner than in the control plot. Although results are comparable to cleared forest stands, standing dead trees in burned forest stands attenuate incoming short‐wave radiation, wind speed, temperature, and snow accumulation on the surface to a greater degree than is observed in cleared stands. Copyright © 2011 John Wiley & Sons, Ltd.
Understanding and treating hoarding: A biopsychosocial perspective
Authors: Tolin David F.
Published: March 2011

This article offers a practice‐friendly review of conceptualizing and treating hoarding based on biological and psychological research. Although hoarding has commonly been conceptualized as a variant of obsessive‐compulsive disorder, research suggests a more complex pattern of overlap with attention deficit‐hyperactivity disorder, organic brain disease, depression, anxiety, personality disorders, and impulsivity. The phenomenon of hoarding is discussed in terms of familial and environmental vulnerabilities, maladaptive cognitive process, maladaptive cognitive content, and maladaptive behavioral patterns. The article concludes with a summary of treatment efficacy and 10 promising clinical practices. © 2011 Wiley Periodicals, Inc. J Clin Psychol: In Session 67:1–10, 2011.
Working with families of people who hoard: A harm reduction approach
Authors: Tompkins Michael A.
Published: March 2011

Approximately, 3%–5% of the U.S. population suffers from compulsive hoarding but others suffer as well, in particular, the family members who care about them. This article describes the manifold ways family members suffer because of their loved one's hoarding behavior, including the frustration and hopelessness many family members experience in the face of their loved one's steadfast refusal to accept help for their hoarding problem. The article presents harm reduction as a way for family members to help a loved one who is unwilling to accept treatment of the hoarding problem. The article then presents two clinical examples—a private hoarding situation and a public hoarding situation—to illustrate the application of harm reduction to hoarding. © 2011 Wiley Periodicals, Inc. J Clin Psychol: In Session 67:1–10, 2011.
L1 Cell adhesion molecule (L1CAM) expression at the cancer invasive front is a novel prognostic marker of pancreatic ductal adenocarcinoma
Authors: Tsutsumi Shinji , Morohashi Satoko , Kudo Yasuyuki , Akasaka Harue , Ogasawara Hiroshi , Ono Masashi , Takasugi Kaori , Ishido Keinosuke , Hakamada Kenichi , Kijima Hiroshi
Published: March 2011

Background and Objectives

Pancreatic ductal adenocarcinoma (PDAC) is one of the most extremely aggressive cancers with a poor prognosis after curative resection. L1 cell adhesion molecule (L1CAM) is a 200–220 kDa type I transmembrane glycoprotein of the immunoglobulin superfamily, which has been shown to affect the prognosis of several cancers. No clinicopathological significance of L1CAM expression has been examined at the invasive front of PDAC. In this study, we examined the relationship between L1CAM expression and clinicopathological features in PDAC by immunohistochemistry.

Methods

One hundred seven surgically resected specimens of PDAC were immunohistochemically examined using a monoclonal antibody against L1CAM.

Results

Positive expression of L1CAM was found in 23 of 107 cases with PDAC. In most cases (21/23), L1CAM expression was localized at the invasive front of the tumor tissue. Positive expression of L1CAM was significantly correlated with the histological grade, lymph node involvement, and distant metastasis. In univariate analysis, a positive expression of L1CAM was associated with short overall survival (P = 0.0002), and this was significant in multivariate analysis (P = 0.009).

Conclusions

L1CAM could play an important role in the invasive process in vivo, and is thought to be a good indicator of prognosis in PDAC. J. Surg. Oncol. 2011;103:669–673. © 2011 Wiley‐Liss, Inc.
Irreversible electroporation of the pancreas: Definitive local therapy without systemic effects
Authors: Bower Matthew , Sherwood Leslie , Li Yan , Martin Robert
Published: March 2011

Background

The use of thermal tumor ablative techniques in the pancreas is limited due to the risk of pancreatitis and damage to major vascular structures. Irreversible electroporation (IRE) is a non‐thermal ablation technique that could allow ablation in the pancreas while preserving vital surrounding blood vessels. The aim of this study was to assess the safety and ablation volume of IRE in porcine pancreatic tissue.

Methods

IRE of swine pancreases was performed using an open technique and ultrasound guidance and the animals were followed for 72 hr, 7 days, and 14 days post‐IRE.

Results

All pigs underwent IRE, with one pig was unsuccessful after three attempts using at 3,000 V due to inability to achieve a stable current. All animals recovered well and revealed only mild adhesions, no ascites, and no pancreatic necrosis. All animals had transient increases in amylase and lipase that normalized on post‐IRE day 3. Pathologic analysis revealed that ablation defects (median size 3 cm × 2.8 cm) were seen in electroporated areas with significant destruction of the pancreatic tissue with patent vascular structures.

Conclusions

This animal model demonstrates that IRE of the pancreas performed at an optimal voltage is well tolerated, with rapid resolution of pancreatic inflammation and preservation of vascular structures. J. Surg. Oncol. 2011;104:22–28. © 2011 Wiley‐Liss, Inc.
Investigation of silanol activity on the modified silica surfaces using microcalorimetric measurements
Authors: Buszewski Bogusław , Bocian Szymon , Rychlicki Gerhard
Published: March 2011

A detailed description of the stationary‐bonded phase surface in reversed‐phase liquid chromatography (RPLC) is a topic of great interest in separation sciences. For this purpose, the thermal effects connected with solvent adsorption on the series of octadecyl stationary‐bonded phases were investigated. Microcalorimetric study of organic solvent heat of immersion of the stationary‐phase and chromatographic measurements of the silanol activity were executed. Good correlation between the heat of immersion of different solvents and the residual silanol activity obtained from chromatographic tests of various stationary phases are observed. The present data suggest that measurement of solvent adsorption heat governed by polar interaction with residual silanols may be a useful tool for the determination of silanol activity and surface topography. The present methodology allows determining the access of the solvent molecules to the residual silanols on the chemically bonded phase surface based on silica gel.
Pulmonary vein inflow artifact reduction for free‐breathing left atrium late gadolinium enhancement
Authors: Moghari Mehdi H. , Peters Dana C. , Smink Jouke , Goepfert Lois , Kissinger Kraig V. , Goddu Beth , Hauser Thomas H. , Josephson Mark E. , Manning Warren J. , Nezafat Reza
Published: March 2011

Two‐dimensional “pencil‐beam” navigator, placed on the right hemidiaphragm, is used for free‐breathing late gadolinium enhancement of the left atrium in patients with atrial fibrillation. The pencil‐beam navigator creates an inflow artifact in the right pulmonary veins and atrial wall that may obscure local pulmonary vein and left atrium scars. To reduce this artifact, we propose a large slab right hemidiaphragm projection navigator that measures the respiratory motion while reducing the associated inflow artifact. Eighteen subjects underwent pulmonary vein late gadolinium enhancement using the pencil‐beam and projection navigator. Subjective inflow and respiratory motion artifact scores (1 = severe, 2 = moderate, 3 = mild, and 4 = none) from two blinded readers were compared. The artifact scores were 3.8 ± 0.4 and 2.1 ± 0.7 for the projection and pencil‐beam navigators, respectively (P < 0.001). Respiratory motion artifact scores were similar between the two techniques (3.0 ± 0.5 vs. 3.1 ± 0.5 for projection vs. pencil‐beam navigator). The proposed method greatly reduces the inflow artifact in free‐breathing pulmonary vein late gadolinium enhancement while allowing adequate respiratory motion compensation. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Microstrip Butler matrix design and realization for 7 T MRI
Authors: Yazdanbakhsh Pedram , Solbach Klaus
Published: March 2011

This article presents the design and realization of 8 × 8 and 16 × 16 Butler matrices for 7 T MRI systems. With the focus on low insertion loss and high amplitude/phase accuracy, the microstrip line integration technology (microwave‐integrated circuit) was chosen for the realization. Laminate material of high permittivity (εr = 11) and large thickness (h = 3.2 mm) is shown to allow the best trade‐off of circuit board size versus insertion loss, saving circuit area by extensive folding of branch‐line coupler topology and meandering phase shifter and connecting strip lines and reducing mutual coupling of neighboring strip lines by shield structures between strip lines. With this approach, 8 × 8 Butler matrices were produced in single boards of 310 mm × 530 mm, whereas the 16 × 16 Butler matrices combined two submatrices of 8 × 8 with two smaller boards. Insertion loss was found at 0.73 and 1.1 dB for an 8 × 8 matrix and 16 × 16 matrix, respectively. Measured amplitude and phase errors are shown to represent highly pure mode excitation with unwanted modes suppressed by 40 and 35 dB, respectively. Both types of matrices were implemented with a 7 T MRI system and 8‐ and 16‐element coil arrays for RF mode shimming experiments and operated successfully with 8 kW of RF power. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Feasibility of ultra‐short echo time (UTE) magnetic resonance imaging for identification of carious lesions
Authors: Bracher Anna‐Katinka , Hofmann Christian , Bornstedt Axel , Boujraf Saïd , Hell Erich , Ulrici Johannes , Spahr Axel , Haller Bernd , Rasche Volker
Published: March 2011

The objective of this study was to investigate the potential of ultra short echo time imaging for the assessment of caries lesions and early demineralization. 12 patients with suspected caries lesions underwent a dental magnetic resonance imaging investigation comprising ultra short echo time imaging (echo time = 50 μs) and spin echo imaging. Before the dental magnetic resonance imaging, all patients underwent a conventional clinical dental investigation including visual assessment of the teeth as well as dental x‐ray imaging. All lesions identifiable in the x‐ray could be clearly identified in the ultra short echo time images, but only about 19% of the lesions were visible in the spin echo images. In 19% of all lesions, the lesions could be more clearly delineated in the ultra short echo time images than in the x‐ray images. This was especially the case for secondary lesions. In direct comparison with the x‐ray images, all lesions appeared substantially larger in the dental magnetic resonance imaging data. The presented data provide evidence that caries lesions can be identified in ultra short echo time magnetic resonance imaging with high sensitivity. The apparent larger volume of the lesions in dental magnetic resonance imaging may be attributed to fluid accumulation in demineralized areas without substantial breakdown of mineral structures. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Phase enhancement for time‐of‐flight and flow‐sensitive black‐blood MR angiography
Authors: Kimura Tokunori , Ikedo Masato , Takemoto Shuhei
Published: March 2011

A magnitude‐based MR angiography method of standard time‐of‐flight (TOF) employing a three‐dimensional gradient‐echo sequence with flow rephasing is widely used. A recently proposed flow‐sensitive black‐blood (FSBB) method combining three‐dimensional gradient‐echo sequence with a flow‐dephasing gradient and a hybrid technique, called hybrid of opposite‐contrast, allow depiction of smaller blood vessels than does standard TOF. To further enhance imaging of smaller vessels, a new enhancement technique combining phase with magnitude is proposed. Both TOF and FSBB pulse sequences were used with only 0th‐order gradient moment nulling, and suitable dephasing gradients were added to increase the phase shift introduced mainly by flow. Magnitude‐based vessel‐to‐background contrast‐to‐noise ratios in TOF and FSBB were further enhanced to increase the dynamic range between positive and negative signals through the use of cosine‐function‐based filters for white‐ and black‐blood imaging. The proposed phase‐enhancement processing both improved visualization of slow‐flow vessels in the brains of volunteer subjects with shorter echo time in TOF, FSBB, and hybrid of opposite‐contrast and reduced wraparound artifacts with smaller b values without sacrificing vessel‐to‐background contrast in FSBB. This method of enhancement processing has excellent potential to become clinically useful. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
A molecular MRI probe to detect treatment of cardiac apoptosis in vivo
Authors: Dash Rajesh , Chung Jaehoon , Chan Trevor , Yamada Mayumi , Barral Joëlle , Nishimura Dwight , Yang Phillip C. , Simpson Paul C.
Published: March 2011

Cell death by apoptosis is critical in myocardial diseases, and noninvasive detection of early, reversible apoptosis might be useful clinically. Exogenous Annexin‐V (ANX) protein binds membrane phosphatidylserine, which is externalized in early apoptosis. A molecular MRI probe was constructed with superparamagnetic iron oxide (SPIO) conjugated to recombinant human ANX (ANX‐SPIO). Apoptosis was induced with doxorubicin, a cardiotoxic cancer drug, in culture in neonatal rat ventricular myocytes, cardiac fibroblasts, and mesenchymal stem cells, and in vivo in the mouse heart. ANX‐SPIO was validated using T2*‐weighted 3T MRI. ANX‐SPIO produced T2* signal loss, reflecting iron content, that correlated highly with independent apoptosis markers; bound with high affinity to apoptotic myocytes by competition assay (Ki 69 nM); detected apoptosis in culture much earlier than did TUNEL stain; and revealed fibroblast resistance to apoptosis. With apoptosis in vivo, ANX‐SPIO produced diffuse myocardial T2* signal loss that correlated with increased iron stain and caspase activity. Treatment with an alpha‐1‐adrenergic agonist in vivo reversed apoptosis and eliminated the ANX‐SPIO MRI signal. It is concluded that cardiac MRI of ANX‐SPIO detects early, nonischemic cardiac apoptosis in culture and in vivo, and can identify reversibly injured cardiac cells in diseased hearts, when treatment is still possible. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
A new approach for vertical impedance in radially inhomogeneous soil layer
Authors: Wang K. H. , Yang D. Y. , Zhang Z. Q. , Leo Chin Jian
Published: March 2011

In the past studies on pile vibrations, the soil around the pile is mainly regarded as homogeneous or multi‐layered piecewise homogeneous. However, under most engineering conditions, the surrounding soil becomes seriously disturbed due to construction effects. This may strengthen or weaken the shear modulus of the soil resulting in the soil becoming radially inhomogeneous. As a consequence of this, El Naggar extended Novak's plane‐strain model to account for the radial inhomogeneity by the use of multiple springs connected in series. Rather than using this approach, this paper proposes a new model which is thought to be theoretically more rigorous and one which may be described as complex stiffness transfer model. It is shown that the solution developed in this study agrees well with the more limited solutions of Novak and Dotson and Veletsos under several special conditions. Finally, the scope of application has been enlarged as a result of the generalizations made in the present model. Copyright © 2011 John Wiley & Sons, Ltd.
Spatiotemporal encoding as a robust basis for fast three‐dimensional in vivo MRI
Authors: Ben‐Eliezer Noam , Frydman Lucio
Published: March 2011

Recent studies have described some of the new opportunities that have arisen within the context of ultrafast two‐dimensional imaging with the advent of spatiotemporal encoding methods. This article explores the potential of integrating these non‐Fourier, single‐scan, two‐dimensional MRI principles, with multi‐slice and phase‐encoding schemes acting along a third dimension. In unison, these combinations enable the acquisition of complete three‐dimensional images from volumes of interest within a 1‐s timescale. A number of alternatives are explored for carrying out these very rapid three‐dimensional acquisitions, including the use of two‐dimensional, slice‐selective, spatiotemporal encoding radiofrequency pulses, driven‐equilibrium slice‐selective schemes, and phase‐encoded volumetric approaches. When tested under in vivo conditions, the ‘hybrid’ schemes combining spatiotemporal encoding with k‐encoding imaging principles, proved to be superior to traditional schemes based on echo planar imaging. The resulting images were found to be less affected by field inhomogeneities and by other potential offset‐derived distortions owing to a combination of factors whose origin is discussed. Further features, extensions and applications of these principles are also addressed. Copyright © 2011 John Wiley & Sons, Ltd.
OLEDs für Display‐ und Beleuchtungsanwendungen
Authors: Murano Sven
Published: March 2011

Durch kontinuierliche technologische Verbesserungen haben organische Leuchtdioden (OLEDs) mittlerweile ein Niveau erreicht, das eine starke Penetration der Display‐ und Beleuchtungsmärkte in den nächsten Jahren erwarten lässt. OLEDs werden insbesondere für Anwendungen als Lichtquellen zur Beleuchtung oder Beschilderung zu völlig neuartigen Konzepten führen.
Licht im Kampf gegen Krebs und andere Volkskrankheiten
Authors: Jürgens Marion , Popp Jürgen
Published: March 2011

Optische Technologien werden immer wichtigere Werkzeuge für Lebenswissenschaften und Medizin. Weltweit sind orschungsaktivitäten im Gang, die zum eil durch hoch dotierte öffentliche Förderprogramme unterstützt werden. Auch die Bundesregierung setzt weiter auf die Biophotonik: Seit dem vergangenen Jahr unterstützt sie acht neue Forschungsprojekte. Damit erhöht sich das Gesamtvolumen der öffentlichen und privaten Investitionen im Forschungsschwerpunkt Biophotonik auf rund 90 Millionen Euro.
Optisch‐elektrische Hybridkabel
Authors: Schramm Volker
Published: March 2011

Die technologischen Vorteile beim Einsatz von optisch‐elektrischen Hybridkabeln sind offensichtlich: Der Verbindungsaufwand zwischen den Einsatzstandorten wird minimiert. Leistung und Meßdaten werden in einem Kabel übertragen. Die Verbindung ist bewegungsfähiger. Die Verwendung nur eines Kabels ermöglicht eine größere Packungsdichte. Die produktions‐ und ingenieurstechnische Lieferleistung wird durch nur einen Hersteller für nur ein Kabel erbracht. Der Anwender hat dadurch einen geringeren Koordinationsund Kostenaufwand.
Ein Strahl — Eine Matrix
Authors: Herdt Barbara , Bril Moshe
Published: March 2011

Diffraktive optische Elemente (DOEs) werden genutzt, um mittels Vielstrahlinterferenz an periodischen Strukturen Lichtstrahlen zu formen. Am häufigsten werden sie zur Strahlprofiländerung (Beam Shaping), zur Korrektur von Abbildungsfehlern und zur Strahlteilung (Beam Sampling) eingesetzt. Ihre Vorteile dabei: einfache Handhabung, geringste Justage und geringe Anforderungen an den Eingangsstrahl.
Excellent Prospects for Europe
Authors: Wilkens Markus , Schellberg Florence
Published: March 2011

A recently published study predicts surpassing growth rates for the Photonics sector. Photonics world market expected to reach 439 billion Euros in 2015. Revenues of European companies in Photonics climbed by 12 % to 49 billion Euros from 2005 to 2006.
EUVL — Extreme Ultraviolet Lithography
Authors: Kaiser Winfried , Kürz Peter
Published: March 2011

Do you remember your first cell phone? And what you could do with it? Exactly: make phone calls. It has only been 10 years. And today? Cell phones have mutated into multifunction devices: now you can make phone calls, send text messages, take and send pictures, surf the Internet, listen to MP3s, play games, navigate and even watch movies. Essentially, cell phones tell the success story of the chip industry like no other technical instrument: even more power in an even smaller space at — comparably — even lower prices. It is the increasing power of microchips that influence the development of cell phones.

Optical lithography is a key driver of this success story. In many aspects it is playing a key role in the manufacture of semiconductors. After all, every microchip is produced using the lithography process. Depending on its complexity, it must undergo this process several dozen times. At the same time, it is primarily the advances in optical lithography that enable the continuously rising integration density of microchips. Mammoth efforts are allowing the semiconductor industry and its suppliers to introduce a new technology today, EUV lithography (EUVL), which will continue to drive progress over the next decade through miniaturization. This article deals with the perspectives of EUVL and the challenges of the technology, and reviews its development.
Innovative Beam Guide Systems
Authors: Frank Dieter W.
Published: March 2011

In recent years, the use of lasers in all fields of endeavour has exploded. Laser producers are conquering new market niches with specialized equipment designed to fit the needs of their clients. The output produced by industrial lasers has increased greatly in recent years. Lasers can cut, mark or weld with a power of 10 kW and more. Unfortunately, the transfer of laser energy from the laser to the target still presents great difficulties. Adequate beam guides to direct the laser energy are often not available. Tailor made beam guide solutions are boosting efficiency and reliability in applying lasers to real‐world solutions.
Optical Design of Beam Delivery and Beam Forming Systems
Authors: Eppich Bernd
Published: March 2011

The layout of beam delivery and/or beam forming optical systems is a recurring task in development and application of laser systems and necessarily requires adequate simulation tools. Accurate and precise simulation of the propagation of laser beams through optical systems, with the aim of predicting the beam profile at desired locations, is challenging. It requires detailed characterization of the initial beam and application of sophisticated software, which usually can only be operated by highly qualified personal. Relaxing the requirements to the prediction of more general beam parameters like beam diameter, beam divergence, and Rayleigh length, important layout jobs can be accomplished by ease‐to‐use simulation tools based on a few beam parameters measured according to the well‐known ISO 11146 standard.
Titan‐Saphir Laser
Authors: Frowein Helmut
Published: March 2011

In den letzten 20 Jahren hat sich der Titan‐Saphir Laser zum Arbeitspferd der Spektroskopie und in vielen anderen Bereichen der Forschung entwickelt. Aus den Versuchsaufbauten der achtziger Jahre sind inzwischen stabile Systeme geworden, heute kann man Turn‐Key‐Systeme kaufen mit Pulsenergien von wenigen Nanojoule bis fast in den Joulebereich. Ti:Sa steht für Terawattlaser genauso wie für ultrapräzise Metrologie. Mit der Stabilität der Laser hat sich auch die Zahl der Anwendungen vergrößert, und die Entwicklung ist noch lange nicht am Ende.
Europäische Bildverarbeitungs‐Industrie weiter auf Wachstumskurs
Authors: Schwarzkopf Patrick
Published: March 2011

Die industrielle Bildverarbeitung (IBV) ist längst zu einem Synonym für Wettbewerbsfähigkeit, hohe Qualität und Kosteneffizienz in der industriellen Produktion geworden. Aber auch außerhalb der Fabrik erobert sich diese universell einsetzbare Technologie schnell neue Märkte — in der Verkehrstechnik, im Labor, im Sicherheitsbereich oder als Bestandteil des Automobils. Dementsprechend positiv entwickeln sich derzeit die Zahlen im Bereich IBV.
Glänzend gelöst
Authors: Schmidgall Thomas
Published: March 2011

In der modernen Qualitätssicherung sind industrielle Bildverarbeitungssysteme ein unentbehrlicher Helfer. Sie sorgen für eine schnelle Qualitätsprüfung und Fehlerdetektion im laufenden Fertigungsprozess. Bei der Kontrolle von glänzenden Oberflächen stieß die automatisierte Bildverarbeitung bisher an ihre Grenzen. Hier ist das Erkennen von Einschlüssen, Textur‐ oder Farbabweichungen immer noch stichprobenartig dem menschlichen Auge vorbehalten. Ein neues Prüfverfahren ermöglicht jetzt die 100 % in‐process Prüfung von glänzenden und spiegelnden Teilen.
Von der strukturierten Faser zum Faserlaser
Authors: Reichel Volker , Schuster Kay , Kobelke Jens , Kirchhoff Johannes , Bartelt Hartmut
Published: March 2011

Faserlaser sind kompakt, langlebig und haben eine ausgezeichnete Strahlqualität. Deshalb finden Faserlaser verschiedenster Ausgangsleistungen zunehmendes Interesse in der Mikrobeschriftung, Mikromaterialbearbeitung und in der Automobilindustrie. In diesem Artikel sollen neben den Anwendungsmöglichkeiten dieser neuartigen Lichtquellen vor allem auch die erforderlichen Technologien zur Herstellung von strukturierten und laseraktiven Fasern vorgestellt werden.
Neue optische Beschichtungen
Authors: Ehlers Henrik , Lappschies Marc , Beermann Nils , Ristau Detlev
Published: March 2011

Gegenwärtig gilt das Ionenstrahl‐Zerstäuben (Ion Beam Sputtering, IBS) als das Beschichtungsverfahren der Wahl, wenn im Bereich der optischen Beschichtungen höchste Qualitätsansprüche erfüllt werden müssen. In jüngster Zeit konnte das IBS‐Verfahren durch Kombination mit neuen Prozesskontrolltechniken und Materialmischtechniken für die Herstellung von Rugate‐Filtern mit kontinuierlichen Brechungsindexverläufen in seiner Anwendungsbreite noch einmal deutlich gesteigert werden.
Messen mit Subpixel‐Genauigkeit: Legende und Wirklichkeit
Authors: Schuster Norbert
Published: March 2011

Die 2‐D‐Messtechnik mit elektronischen Bildaufnehmern hat sich zu einer Schlüsseltechnologie der Automatisierung entwickelt. Dabei hat die Frage nach der erreichbaren Genauigkeit oberste Priorität. Sie entscheidet über die Wahl der Kamera, der Abbildungsoptik und der Beleuchtung.
Metrology under Control
Authors: Kozma Ida Z. , Holzwarth Ronald , Sizmann Andreas , Mei Michael
Published: March 2011

Mode‐locked femtosecond lasers enable ultra precise measurements based on fundamental constants. Although in terms of pulse properties the performance of the state‐of‐the‐art Ti:sapphire lasers are yet superior to alternative ultrafast laser technologies, it is the fiber laser technology that facilitates the development of breakthrough applications outside the laboratory environment. Reliability and robustness of fiber lasers are attractive features for industry, while the unique SWaP factor (size, weight and power) designates the fiber‐based optical frequency combs a promising enabling technology even for space science.
Terahertz with Electronic Delay
Authors: Posthumus Jan
Published: March 2011

Terahertz radiation has recently captured the imagination of many researchers and visionaries alike. Today, the most advanced means of terahertz spectroscopy are based on femtosecond lasers. Meanwhile the advantages of ultrafast fiber lasers are widely recognised. The newly introduced ECOPS technique makes another step forward by removing the need for mechanical delay stages.
Ultrafast Laser Supports Bio‐Imaging Applications
Authors: Ziegs Werner
Published: March 2011

A wide range of bio‐imaging methods have evolved using ultrafast lasers, including numerous variants on multiphoton fluorescence excitation microscopy (MPE) and other types of non‐linear optical effects. Laser manufacturers have supported these cutting edge imaging techniques with a variety of new laser tools and accessories. This article reviews recent developments in ultrafast lasers and examines some research that exploits their performance.
Silicon‐based Photonics
Authors: Iannone Eugenio
Published: March 2011

The phenomenal increase in the amount of traffic generated by new video‐based telecommunications services such as IPTV is rapidly pushing optical transmission equipment towards higher bandwidth and a high quality of service. This trend demands a radical change in the cost model for optical telecommunications systems. It is no longer acceptable to provide high cost, low volume “jewels” — future development must be towards high volume, low cost commodities that can be more widely implemented throughout the network. One answer to this demand is the development of silicon‐nanophotonics.
Interview mit Theodor W. Hänsch
Authors: Wengenmayr Roland
Published: March 2011

2005 erhielt Theodor W. Hänsch den Nobelpreis für Physik [1]. Der Direktor am MPI für Quantenoptik und Professor an der LMU München wird damit für seine Beiträge zur Laser‐Präzisionsspektroskopie gewürdigt, besonders für die Entwicklung des optischen Frequenzkamms. Außerdem verliehen ihm die Deutsche Physikalische Gesellschaft und die Gesellschaft Deutscher Chemiker den diesjährigen Otto‐Hahn‐Preis. Roland Wengenmayr sprach mit ihm über seinen Lebensweg als Forscher und seine aktuelle Arbeit.
Das perfekte Paar
Authors: Reeb Winfried
Published: March 2011

In der optoelektronischen Messtechnik spielt die optimale Abstimmung zwischen Emitter und Detektor die entscheidende Rolle für den reibungsfreien Betrieb von Systemen. Schon bei der Entwicklung ist darauf zu achten, dass bestimmte Bauteile anwendungsspezifisch angepasst werden.
Improved microwave absorption and electrostatic charge dissipation efficiencies of conducting polymer grafted fabrics prepared via in situ polymerization
Authors: Saini Parveen , Choudhary Veena , Dhawan Sundeep. K.
Published: March 2011

Polyaniline (PANI) and polypyrrole (PPY) were grafted over cotton fabrics by in situ polymerization. FTIR spectra show systematic shifting of bands corroborating surface grafting of conducting polymers on cotton fabric. SEM images revealed that the surface coating of PANI was smoother than PPY. However, better control over coating thickness and uniformity was achieved in PPY fabric. The probable formation mechanism of grated fabrics has also been proposed. The good thermal stability and acceptable electronic conductivity values indicate that these fabrics could be used for electrostatic charge dissipation and microwave absorption. The antistatic studies have shown complete charge dissipation (decay time <0.01 sec). The microwave absorption studies of the conducting fabrics in X‐band (8.2–12.4 GHz) show absorption dominated total shielding effectiveness in the range −11.3 to −11.7 dB (>92% attenuation) and −9.2 to −9.6 dB (>88% attenuation) for fabrics grafted with PPY and PANI, respectively. Copyright © 2011 John Wiley & Sons, Ltd.
Characterization and antibacterial activity of chitosan‐based composites with polyester
Authors: Wu Chin‐San
Published: March 2011

The effects of replacing poly(butylene succinate adipate) (PBSA) with acrylic acid‐grafted PBSA (PBSA‐g‐AA) on the structure and the properties of a PBSA/chitosan composite were investigated. The properties of both PBSA‐g‐AA/chitosan and PBSA/chitosan were compared using Fourier transform infrared (FTIR), 13C nuclear magnetic resonance (NMR), X‐ray diffraction (XRD), and an antibacterial activity test. With PBSA‐g‐AA in the composite, the compatibility with chitosan and, consequently, the properties of the composite became greatly improved due to the formation of ester and imide groups that conferred better dispersion and homogeneity of chitosan in the matrix. Composites containing PBSA‐g‐AA/chitosan exhibited superior mechanical properties due to greater compatibility between the two components. Moreover, chitosan enhanced the antibacterial activity of the composites. Composites of PBSA‐g‐AA or PBSA that contain chitosan have better antibacterial activity. The functionalized PBSA‐g‐AA/chitosan composites showed markedly enhanced antibacterial properties due to the carboxyl groups of acrylic acid, which acted as coordination sites for the chitosan phase, allowing the formation of stronger chemical bonds. Copyright © 2011 John Wiley & Sons, Ltd.
Homo‐ and copolymerization of norbornene and 5‐norbornene‐2‐yl acetate with bis‐(β‐ketonaphthylamino)palladium(II)/B(C6F5)3 catalytic system
Authors: Huang Ran , He Xiaohui , Chen Yiwang , Nie Huarong , Zhou Weihua
Published: March 2011

The polymerization of norbornene with bis(β‐ketonaphthylamino) palladium(II), Pd{CH3C(O)CHC[N(naphthyl)]CH3}2, in combination with tris(pentafluorophenyl)borane (B(C6F5)3), was investigated by varying the B:Pd(II) molar ratio, monomer concentration, reaction temperature, and time. The catalytic activity was found to reach 2.8 × 104 gPolymer/(molPd•h) and the obtained polynorbornene (PNBE) was confirmed to be vinyl addition polymer and showed good thermo‐stability (Tdec > 350°C), but exhibited poor solubility in organic solvents due to the relative higher stereo regularity. Pd{CH3C(O)CHC[N(naphthyl)]CH3}2/B(C6F5)3 system is also an active catalyst for copolymerization of norbornene and 5‐norbornene‐2‐yl acetate (NBE‐OCOCH3) in toluene with moderate yields (in 9.2–36.5% yields) and produces the addition‐type copolymer with relatively high molecular weights (0.96 × 104–2.13 × 104 g/mol). The incorporation of functional group in the copolymer can be controlled up to 0.9–23.5 mol% by varying the NBE‐OCOCH3 monomer feed ratios from 10 to 90%. The copolymers are proved to be noncrystalline and show good solubility in common organic solvents and excellent thermal stability up to 350°C. Copyright © 2011 John Wiley & Sons, Ltd.
Preparation, characterization, and properties of polyamic acid nano‐emulsion
Authors: Ding Fuchuan , Tong Yuejin , Luo Xiaolan , Guan Huaimin , Hu Binghuan
Published: March 2011

A facile method was developed to prepare polyamic acid (PAA) nano‐emulsion using a non‐aqueous emulsification. The resultant PAA nano‐emulsion was characterized by light‐scattering particle size analysis, transmission electron microscopy (TEM), zeta potential, and conductivity analyses. It was found that polyamic acid salt (PAS), formed by partially neutralizing PAA at the carboxylic groups using triethyl amine (TEA), was of great importance for nano‐emulsification. The effect factors on the formation of PAA nano‐emulsion were investigated. To get a stable PAA nano‐emulsion in methanol (precipitant), the following ratios are required: amine/COOH (molar ratio) = 0.6–0.7, precipitant/solvent (mass ratio) = 1.5–2.25. A PAA nano‐emulsion with droplets ranging in size from 50 to 100 nm was obtained under optimized conditions. The driving force for the formation of PAA nano‐emulsion was also discussed. Copyright © 2011 John Wiley & Sons, Ltd.
Polyimide ionomer containing superacid groups
Authors: Saito Jumpei , Tanaka Manabu , Hirai Michiko , Nanasawa Masato , Miyatake Kenji , Watanabe Masahiro
Published: March 2011

A novel sulfonated polyimide (SPI) copolymer containing pendant perfluorosulfonic acid groups was synthesized and their properties were investigated. 2‐(2,4‐Diaminophenoxy)‐1,1,2,2‐tetrafluoroethanesulfonic acid (5) was synthesized from 2,4‐diaminophenol dihydrochloride via acetylation, perfluoroalkylation, and sulfonation. Polycondensation of 1,4,5,8‐naphthalenetetracarboxylic dianhydride, monomer 5, and 3,5‐bis(4‐aminophenyl)‐1H‐1,2,4‐triazole gave the title polyimide 6. The obtained polyimide copolymer 6 was soluble in polar organic solvents and its chemical structure and ion exchange capacity were confirmed by 1H and 19F NMR spectra. The copolymer 6 was thermally stable up to ca. 180°C and showed 6.6 × 10−4 S cm−1 of the proton conductivity at 80°C in water. Copyright © 2011 John Wiley & Sons, Ltd.
Synthesis of bis‐triethoxysilane endcapped polyurethane/urea and its self‐assembly morphologies with the assistance of hydrogen ion
Authors: Gao Feng , Huang Shiqiang , Ku Bin , Chen Ming , Wu Jun , Wang Jinzhao
Published: March 2011

A type of bi‐triethoxysilane endcapped polyurethane/urea (SPU) with well‐defined structure was synthesized through the reaction of polyethylene glycol (PEG), 2, 4‐toluene diisocyanate (TDI) and bis‐[trimethoxysiylpropyl]amine (DB‐520). The structure of the resultant product was confirmed by Fourier transform infrared (FT‐IR) and Nuclear magnetic resonance (1HNMR). Different SPU nanoparticles were obtained with the assistance of hydrogen ion, and their morphologies were characterized by combination of transmission microscopy (TEM) and FT‐IR. The results showed that with increasing the concentration of hydrogen ions, the ratio of condensation accordingly increased, accompanying with the nanoparticle's morphology change from sphere to rod. Furthermore, the dispersion mechanism of SPU chains in protonic solution and the arrangement of molecular chains in hybrid particles were proposed. Copyright © 2011 John Wiley & Sons, Ltd.
Quantitative determination of superoxide in plant leaves using a modified NBT staining method
Authors: Grellet Bournonville Carlos F. , Díaz‐Ricci Juan Carlos
Published: March 2011

Introduction – In plants, the ROS (reactive oxygen species) level is tightly regulated because their accumulation produces irreversible damage leading to cell death. However, ROS accumulation plays a key role in plant signaling under biotic or abiotic stress. Although various methods were reported to evaluate ROS accumulation, they are restricted to model plants or provide only qualitative information.

Objective – Develop a simple method to quantify superoxide radicals produced in plant tissues, based on the selective extraction of the formazan produced after nitroblue tetrazolium (NBT) reduction in histochemical staining.

Methodology – Plant leaves were stained with a standard NBT method and the formazan precipitated in tissues was selectively extracted using chloroform. The organic phase was dried and formazan residue dissolved in dimethylsulfoxide–potassium hydroxide and quantified by spectrophotometry. The method was tested in strawberry plant leaves under different stressing conditions.

Results – Formazan extracted from leaves subjected to stress conditions showed similar absorption spectra to those obtained from standard solutions using pure formazan. Calibration curves showed a linear relationship between absorbance and formazan amounts, within the range 0.5–8 µg. Outcomes suggested that formazan was retained in the solid residue of leaf tissues. This protocol allowed us to quantify superoxide radicals produced under different stress conditions.

Conclusions – Chloroform allowed a selective formazan extraction and removal of potential endogenous, exogenous or procedural artefacts that may interfere with the quantitative determination. This protocol can be used to quantify the superoxide produced in plant tissues using any traditional qualitative NBT histochemical staining method.
Derivation of power gain for three types of three dimensional photovoltaics cells
Authors: Flicker Jack , Ready Jud
Published: March 2011

In order to quantify the higher power output seen from solar cells with a three‐dimensional (3D) topology due to the increased interactions between photons and the cell surface, we have derived a formula for the average number of interactions, Γ, between a photon and the cell surface for 3D cells with vertical sidewalls and flat tops. We have derived Γ for three different cell morphologies, an infinite trench in the x‐ or y‐direction, an enclosed box, and an infinite two‐dimensional (2D) array of towers. Monte Carlo simulations were carried out in order to compare computational results for Γ with those derived. For varying distance between features, d, and photon azimuthal angle, the data fits the derived expressions quite well for a large range of values. For varying tower height, the data fits theory well for both the trench and box morphologies, however, theory overestimates the value of Γ for the 2D array of towers. This is due to simplifications made when deriving Γ. However, the error associated with Γ is small enough that it propagates to a measured power output error of less than 1% for cells with an absorbance efficiency of at least 25%. Even with simplifications, the derived expression for Γ should be usable for predicting the increased power output for 3D cells with vertical sidewalls and flat tops. Copyright © 2011 John Wiley & Sons, Ltd.
Operating regimes for second generation luminescent solar concentrators
Authors: Farrell Daniel J. , Yoshida Megumi
Published: March 2011

In this paper, we introduce the concept of first and second generation luminescent solar concentrators. Traditional, first generation devices are characterised by their randomly oriented molecules that absorb sunlight and emit luminescence isotropically. By applying detailed balance to the absorbed and emitted photon fluxes we derive the Shockley–Queisser limit for these devices. It is found that they have inherently low efficiency due to optical losses (the well known reabsorption problem) and also that device performance is strongly affected by the areal ratio between the top and edge surfaces. This latter property makes it very difficult to achieve significant cost reductions because as the edge area is reduced (to lessen the amount of expensive photovoltaic material required for conversion), the efficiency of the system diminishes. First generation concentrators have now approached the fundamental limits which we predict here, thus to achieve a stand‐alone luminescent concentrator that enables significant cost reductions, second generation approaches are now needed. New, second generation devices are characterised by either directional emitters or photonic filters which enhance the waveguiding mechanism, allowing high efficiency and large sizes to be achieved simultaneously. Here we define the fundamental operating regime in which second generation technology must reach to surpass the limit of first generation devices. Copyright © 2011 John Wiley & Sons, Ltd.
Strom aus der Wüste. DLR‐Studien zum Projekt Desertec
Authors: Trieb Franz
Published: March 2011

Studien des DLR über das Potenzial erneuerbarer Energien in Europa, dem Mittleren Osten und Nordafrika kommen zu folgenden Aussagen: Ausgehend von einem existierenden Anteil von 16 % erneuerbarer Energie im Jahr 2000 könnte 2050 ein Anteil von 80 % erreicht werden. Zur Ergänzung der erneuerbaren Energiequellen wird eine effiziente Backup‐Infrastruktur benötigt. Sie liefert eine sichere, bedarfsgerechte Stromkapazität mit schnell reagierenden, erdgasbetriebenen Spitzenlastkraftwerken. Der Stromtransport nach Europa erfolgt mit Hochspannungs‐Gleichstrom‐Übertragung (HGÜ). Wird zwischen 2020 und 2050 mit einem Stromtransfer von 60 TWh/a begonnen, so könnte dieser bis auf 700 TWh/a im Jahr 2050 ausgebaut werden. Die hohe Sonnenstrahlung in MENA und niedrige Übertragungsverluste mit HGÜ von circa 10 % werden in einem konkurrenzfähigen Strompreis von circa 0,05 Euro2000/kWh resultieren. Anstelle einer zu erwartenden Verdoppelung der Kohlendioxidemissionen bis zum Jahr 2050 können diese auf 38 % der Emissionen des Jahres 2000 reduziert werden. Für den gesamten erneuerbaren Kraftwerkspark in EU‐MENA werden 1 % der Landfläche benötigt. Das entspricht der gegenwärtigen Landnutzung für Transport und Verkehr in Europa.
Wenn das Licht den Dreh raus hat. Künstliche chirale Materialien
Authors: Thiel Michael , Gansel Justyna K. , Wegener Martin , von Freymann Georg
Published: March 2011

Chirale Strukturen sind in der Natur allgegenwärtig. Optisch äußert sich Chiralität durch eine Drehung der linearen Polarisation des Lichts. Bei den meisten natürlichen Substanzen sind diese Drehungen allerdings sehr klein, da die Wellenlänge des Lichts um ein Vielfaches größer ist als die chiralen Bauelemente. Die heutige Nanotechnologie erlaubt es, chirale Strukturen auf der Skala der Wellenlänge des Lichts zu realisieren. Dadurch verstärkt sich die Wechselwirkung mit dem Licht dramatisch. Es öffnen sich Polarisationsstoppbänder, die die Ausbreitung von Licht mit einer bestimmten zirkularen Polarisation vollständig unterdrücken können.
Eine kurze Geschichte der Gezeiten. Ebbe und Flut
Authors: Glebe Wolfgang
Published: March 2011

Ebbe und Flut haben auf der Erde ihre Ursache in der Gravitation von Sonne und Mond. Diese zeitabhängigen Effekte hängen von der Stellung des Mondes relativ zur Sonne, der Neigung der Erdachse zur Sonnen‐ und Mondbahn sowie zahlreichen anderen Parametern ab. Diese zeitabhängigen Effekte wirken periodisch. Hinzu kommt die von geografischen Gegebenheiten abhängende “Reaktion” der Ozeane auf die Gezeitenkraft. Hierbei spielen auch Interferenzen von Flutwellen eine Rolle.
Magnetoelektrische Kopplung an Metalloberflächen
Authors: Gerhard Lukas , Ernst Arthur
Published: March 2011

Bei vielen gängigen Speichermedien wie Festplatten wird die Information magnetisch geschrieben und gelesen. Höhere Speicherdichten könnten Verfahren ermöglichen, bei denen man die magnetische Struktur eines Festkörpers durch ein elektrisches Feld ändert. In enger Zusammenarbeit zwischen dem Max‐Planck‐Institut für Mikrostrukturphysik, der Universität in Halle und dem Karlsruher Institut für Technologie ist es gelungen, mit Hilfe einer solchen magnetoelektrischen Kopplung die magnetische Ordnung in metallischen Nanostrukturen durch ein elektrisches Feld zwischen zwei stabilen Zuständen hin‐ und herzuschalten.
Sehen und nicht gesehen werden
Authors: Rolfs Claus
Published: March 2011

An der Augenstellung eines Tieres kann man seine Ernährungsweise ablesen. Jäger, wie Katze, Löwe oder Eule, haben stets beide Augen nach vorne gerichtet. Dadurch ist ihr Gesichtsfeld nach hinten zwar drastisch eingeschränkt, aber nach vorne überlappen sich die beiden Sehfelder ihrer Augen stark. Das hilft ihnen, eine Beute scharf anzupeilen. Gejagte Tiere wie Kaninchen oder Goldfische haben hingegen die beiden Augen an der Seite des Kopfes, so dass sie möglichst weit nach hinten sehen können, ohne den Kopf zu drehen. So haben sie stets die gesamte Umgebung im Blick.
Multicomponent supramolecular thermoplastic elastomer with peptide‐modified nanofibers
Authors: Wisse Eva , Spiering A. J. H. , Dankers Patricia Y. W. , Mezari Brahim , Magusin Pieter C. M. M. , Meijer E. W.
Published: March 2011

Bioactive nanofibers present a promising synthetic niche for in vivo applications due to their morphological and functional resemblance to the extracellular matrix. Potentially interesting nanofibers are constructed from the hard‐segment regimes in well‐defined thermoplastic elastomers (TPEs). The supramolecular interactions between these hard segments cause physical crosslinking by the formation of nanofibers and provide excellent mechanical properties. Here, we make use of a new class of biocompatible supramolecular TPEs, in which both the formation of the main chain and the hard block is based on multiple hydrogen‐bonding interactions. A self‐assembly process is explored to arrive at well‐defined peptide‐modified nanofibers embedded in a biocompatible soft matrix. Crucial for the success in the synthetic design is the use of an exact match between the molecular recognition units of the peptide and the supramolecular unit that takes care of forming the supramolecular nanofibers of the TPE. Evidence for the strong anchoring of the modified peptides in the hard‐segment nanofibers of the supramolecular TPE is provided by simple extraction experiments. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011