bluuebunny/crossref_metadata_2025 huggingface dataset:
Laser Cooling and Trapping of Neutral Atoms
Authors: Metcalf Harold J. , van der Straten Peter
Published: July 2004

This article presents a review of some of the principal techniques of laser cooling and trapping that have been developed during the past 20 years. Its approach is primarily experimental, but its quantitative descriptions are consistent in notation with most of the theoretical literature.
Spectroscopy, Atomic
Authors: Bonin Keith , Happer William
Published: July 2004

Atomic spectroscopy is the study of the interaction of atoms with electromagnetic radiation of various wavelengths (or frequencies). Its fundamental use has been as an aid to understanding the structure of atoms, but atomic spectroscopy has expanded to include many diverse applications such as monitoring trace impurities in steel mills and determining the elemental composition of stars.

The structure and energy levels of an atom are determined by the interactions between the positively charged nucleus and the surrounding, negatively charged electrons (and the interactions between the electrons themselves). The Coulomb potential dominates all other terms in the Hamiltonian of an atom. The spin–orbit interaction is next in importance and it can be quite large for atoms of high atomic number Z. Smaller terms in the Hamiltonian include the hyperfine interaction and the isotopic shifts due to nuclear mass differences of atoms with the same atomic number Z.

The simplest atoms (ions) are those with one electron whose energy levels and wavefunctions can be calculated analytically. The most widespread and useful model for many‐electron atoms assumes that the electrons move independently of each other in a central, self‐consistent potential, which represents the mean Coulomb energy of an electron due to the attraction of the nucleus and the repulsion of the other electrons. Residual Coulomb interactions between the electrons and other interactions neglected in the single‐particle model are accounted for with perturbation theory to provide estimates for the energy levels of the atoms. Selection rules on the allowed changes of atomic quantum numbers predict which pairs of levels can give rise to strong emission or absorption of light.

A typical spectroscopic measurement requires a light source, some optics for transporting the light, an atom source in the case of absorption spectroscopy, a spectroscopic instrument, and a detector. Some common light sources in spectroscopy are lamps, discharges, flames, lasers, and natural sources such as the sun and the stars. Atoms for absorption spectroscopy can be provided by cells, flames, furnaces, and various types of atomic beams. The most common spectroscopic instruments are prism and grating spectrometers, Fabry–Perot interferometers, and light filters. In addition to the human eye, the most widely used detectors are thermal detectors, wherein thetotal incident energyof the absorbed light causes an increase in the thermal motion of electrons in the material; and photon detectors, wherein thenumber of incident photons(and not their total energy) determines the size of the detector's response. Thermal detectors discussed here include thermocouples, bolometers, and pyroelectric detectors. Common photon detectors are photomultiplier tubes, channeltrons, photodiodes, and charge‐coupled device (CCD) arrays.
Fiber Optics
Authors: Nakahara Tsuneo , Tanaka Shigeru , Nishimura Masayuki
Published: July 2004

The optical fiber is one of the most important key technologies that support the current information technology (IT) era. Optical fibers are now widely used not only as an excellent transmission medium for optical communication but also as optical functional devices, such as optical amplifiers. Both optical fibers and their manufacturing technologies have evolved dramatically toward higher performance and improved productivity. Their applications have also been expanded from optical communication to a variety of fields, such as optical sensors. This article reviews various aspects of optical fibers: structures & materials, fabrication techniques, optical characteristics & reliability, and applications.
Filters, Optical
Authors: Dobrowolski J.A.
Published: July 2004

This article reviews the performance of optical filters for the 0.005 to 1000 µm spectral region. The filters described operate in transmitted or reflected light and are intended for use in free‐space optics. The theory of two or more filters placed in series or in parallel is presented. The effect of surface reflections on the performance of the filters is discussed. Optical filters can be based on many different physical principles. Brief explanations are given of the modes of operation of filters based on absorption, reflection, interference in thin films, holography, scattering, diffraction, and interference of polarized light. The principal advantages and disadvantages of filters based on these phenomena are discussed. Filters can also be classified according to the functions that they are intended to perform. In this article the following generic filter types are considered: antireflection coatings, neutral attenuators, narrow band, medium‐band and wideband reflectors, short‐ and long‐wavelength cutoff filters, narrowband transmission filters, rejection filters, neutral‐ and color‐selective beam splitters and correction or gain flattening filters. For each of the above filter types, spectral transmittance or reflectance curves are presented that correspond to representative filters based on a number of the above‐mentioned physical principles. Information is provided on how to specify the performance of the various filter types.
Spectroscopy, Photoacoustic
Authors: Harren Frans J. M. , Laarhoven Lucas J. J.
Published: July 2004

After a short introduction and description of particular features of the equipment used, attention is centered on applications. Solids, surfaces, and solutions have been studied by photoacoustic spectroscopy; recent work is quoted. Gas‐phase investigations are discussed with emphasis on trace gas detection. Especially, applications in plant physiology and microbiology are considered.
Electro‐optic Imaging
Authors: Kürbitz Gunther
Published: July 2004

This article deals with electro‐optical means to see in nonvisible spectral regions and at very low light levels and to produce visible imagery. The wavelength regions covered range from UV (200 nm to 400 nm) to the thermal IR (8 µm to 14 µm). The visible spectrum band from 350 nm to 750 nm is covered only insofar, as very low light levels are concerned, that is, the use of image‐intensifier systems is required. For every waveband, the physical properties of the scene and the atmosphere as well as the corresponding technologies to transform the scene under consideration into a visible representation are described. That includes optics, detectors, and cooling systems (if required). Performance parameters for the systems are described as far as available.
Electro‐optic Devices
Authors: Maldonado Theresa A.
Published: July 2004

Electro‐optic devices can be designed to modulate various properties of a light wave, including phase, polarization, amplitude, frequency, and even its direction of propagation. Research over the years has focused on developing materials and complementary device geometries that together can yield desirable device performance for a large number of applications. This chapter provides an overview of the fundamental modes of operation for devices that alter the optical properties of materials in a controlled way for achieving light modulation. A mathematical treatment of light propagation in anisotropic and electro‐optically active media is presented to enable the device designer to quantify the modulation of light as well as the effects of slight misalignments of the structure on polarization and energy flow. Various classes of materials investigated for electro‐optic devices are presented; these include inorganic crystals, organic crystals, liquid crystals, semiconductors, and dye‐doped polymers. Possible device geometries include bulk, integrated optical waveguides, and optical fibers. In addition, performance criteria are defined, and a wide range of applications for these devices are summarized.
Laser Isotope Separation
Authors: Letokhov Vladilen , Ryabov Evgeny
Published: July 2004

This paper gives in a concise form, an idea of the principles of various laser isotope separation methods, the current status of studies in this field, and industrial applications of laser isotope separation techniques.
Lasers, ExtremeUVand SoftX‐ray
Authors: Nilsen Joseph
Published: July 2004

Two decades ago, very large sources such as the building size ICF lasers were used as the energy sources to drive the first X‐ray lasers. Tremendous progress has been made over the last two decades to produce tabletop, high‐repetition rate X‐ray lasers that can be used as tools for applications. With the use of high‐reflectivity multilayer mirrors, many of the standard optical techniques such as interferometry can be extended to the soft X‐ray regime between wavelengths of 10 and 50 nm. The dominant X‐ray laser schemes are the monopole collisional excitation lasers either driven by chirped pulse amplification (CPA) laser systems or capillary discharge. The CPA systems drive lasing in neon‐like or nickel‐like ions, typically in the 10‐ to 30‐nm range, while the capillary system is currently limited to driving neon‐like ions at a longer wavelength near 50 nm. Most researchers use nickel‐like ion lasers near 14 nm because they are well matched to the Mo:Si multilayer mirrors, which have peak reflectivity near 13 nm, and are an essential component of applications such as X‐ray laser interferometry.
Light and Lighting Systems
Authors: Bullough John D. , Rea Mark S.
Published: July 2004

Lighting is the application of visually effective optical radiation. This chapter provides the reader with some basic information about lighting terminology and technologies (lamps, ballasts, luminaires, and controls), and the results of recent research on the effective use of lighting. This article supplements the articles on
COLOR VISION
;
COLORIMETRY
;
OPTICAL RADIATION SOURCES AND STANDARDS
; and
PHYSIOLOGICAL OPTICS
.
Optical Coatings
Authors: Macleod Angus
Published: July 2004

Optical coatings consist of thin uniform layers of material over a surface. Interference effects combine with the intrinsic properties of the materials to modify the specular properties of the surface without altering its power. Antireflection coatings reduce reflection losses, high‐reflectance coatings increase the reflectance, others divide or combine light beams perhaps according to their wavelength or direction, some are purely decorative, and there are many others of different types.
Optical Design
Authors: Mouroulis Pantazis
Published: July 2004

The principles and practices of optical design are reviewed. The necessary background knowledge in geometrical optics, aberrations, and image formation theory is outlined. The process of optical design is described, with emphasis placed on real‐life challenges faced by the designer.
Optical Fabrication
Authors: Yi Allen Y.
Published: July 2004

Traditional optical fabrication processes utilize abrasive grinding, lapping to shape the glass optics and polishing to achieve an optical surface finish. The introduction of numerical control technology has resulted in higher productivity and better quality for glass optical fabrication. For medium‐ to high‐volume production, injection molding of aspherical plastic lenses is more economically feasible. Very recently, compression molding process has also emerged as a possible solution to high‐volume glass aspherical lens manufacturing. For low‐volume applications that include optical molds and high‐precision optics, special polishing techniques have been developed.
Optical Illusions
Authors: Hurlbert Anya
Published: July 2004

Visual illusions are tools with which vision scientists probe the visual system. Illusions are misperceptions of reality; some arise from limitations of the eye in image formation, and are rightly calledopticalillusions; some from neural adaptation, others from fundamental mechanisms of image reconstruction and interpretation that must operate even in the presence of inadequate, misleading, conflicting, or no sensory information. This chapter samples illusions of these different types in the perception of different visual attributes: lightness, color, size, shape, motion, and depth.
Optical Networks
Authors: Alferness Rod C. , Kogelnik Herwig , Wood Thomas H.
Published: July 2004

With the explosion of capacity demands driven by the Internet, optical networking systems are experiencing tremendous growth and are providing increasingly high transmission capacities. As importantly, with the advent of the optical amplifier and wavelength‐division multiplexing (WDM), optics is playing a larger role in networking and is extending further to the edge of the network. Once limited to long‐haul point‐to‐point systems, the industry is now commercializing multipoint metro WDM ring systems that include software‐controlled optical wavelength add/drop multiplexers and will soon be capable of offering large optical cross connects. These optical network elements, together with network‐management software, will enable rapid provisioning of wavelength services, as well as rapid network restoration. In addition, as the cost of optics is driven down and the demand for bandwidth to businesses and residential customers continues to grow, optical systems are extending out from the network core and metro to access applications. The confluence of a proliferation of broadband service applications and rapidly maturing optical technology are literally driving optical systems into all segments. Increasingly, optics is literally everywhere.
Polarized Light, Basic Concepts of
Authors: Huard Serge J.
Published: July 2004

Polarization of light is a consequence of the vectorial nature of electromagnetic waves. This concept must be taken into account in a large number of optical phenomena such as birefringence, modulation of light, and propagation in optical devices. A representation of the states of polarization will first be analyzed. The propagation of light in linear or circular anisotropic media is carried out in the context of the phase velocity of the eigenstates of propagation. The evolution of a state of polarization traveling through a complex optical device will be finally presented.
Morphosynthesis of Molecular Magnetic Materials
Authors: Dujardin E. , Mann S.
Published: July 2004

Although molecule‐based materials can combine physical and chemical properties associated with molecular‐scale building blocks, their successful integration into real applications depends also on higher‐order properties, such as crystal size, shape, and organization. New approaches involving templating and self‐ or facilitated assembly of nanoscale building blocks to prepare novel multifunctional molecular magnetic materials with complex form and organization are described.
The concept of retailer value: A means‐end chain analysis
Authors: Skytte Hans , Bove Karsten
Published: July 2004

It is a well‐established fact that creating value for customers is a very important source of competitive advantage. However, no researchers have yet analyzed or defined what is meant by retailer value. In this study, building on a solid theoretical background, we propose a definition of “retailer value.” Subsequently, this concept has been used in an empirical study of retail chains in Denmark and Germany. The study was designed as a means‐end chain approach to the buying of pork and fish products by retail buyers. The results revealed that it is possible to analyze the hierarchy between attributes, consequences, and values sought by retail buyers when buying for their companies, and to identify relevant differences across countries and products. These differences across the value maps are used to propose ideas for how manufacturers of pork and fish products can improve their marketing activities and thereby obtain competitive advantage. [EconLit citations: L660, L810.] © 2004 Wiley Periodicals, Inc. Agribusiness 20: 323–345, 2004.
Captive supplies and cash market prices for fed cattle: The role of delivery timing incentives
Authors: Schroeter John R. , Azzam Azzeddine
Published: July 2004

The use of non‐cash methods of procuring fed cattle for slaughter has led to concern about the effect of these so‐called “captive” supplies on cash market prices. Some empirical evidence suggests that there is a negative short‐run relationship between the two: Cash market prices tend to be low in weeks in which captive supply shipments are high. We advance a different perspective on the relationship between captive deliveries and cash prices, arguing that the incentives that influence cattle delivery‐scheduling decisions could lead to a negative relationship, not between the contemporaneous levels of captive shipments and price, but between the volume of captive deliveries, on the one hand, and an ex ante expectation of a week‐to‐week price change, on the other. Econometric testing provides some evidence of this empirical regularity in the cattle procurement activities of four large packing plants in Texas in the mid‐1990s. [EconLit citations: Q130, L140.] © 2004 Wiley Periodicals, Inc. Agribusiness 20: 347–362, 2004.
Australian wines in the British wine market: A hedonic price analysis
Authors: Steiner Bodo E.
Published: July 2004

The market share of New World wines sold in many European countries has increased dramatically over the past decade. More aggressive marketing, together with a more distinct and recognizable labeling scheme, are often regarded as the keys to the marketing success of these new wines. This article employs hedonic price analysis to identify the values that marketers and consumers place on the information carried by the label of Australian wines in the British wine retail market. Although many grape varieties are given a highly distinct valuation by market participants, our results also suggest that consumers consider regions jointly with grape varieties as proxies for brands. This contrasts with the general observation that grape varietal labeling is the distinctive feature of New World wines. Marketing implications are examined by considering the revenue impact of changes in labeling at the retail level. [JEL citations: L150, D12, C21.] © 2004 Wiley Periodicals, Inc. Agribusiness 20: 287–307, 2004.
Are cattle on feed report revisions random and does industry anticipate them?
Authors: Mills Jeffrey B. , Schroeder Ted C.
Published: July 2004

Cattle on Feed (COF) reports are the most important source of cattle supply information for the beef industry. Accuracy of these reports is critical, as they have marked impacts on current and expected fed cattle market prices and influence resource allocation decisions. This study investigates whether COF report revisions are unbiased, random, and anticipated by beef industry analysts. Initial COF reports are biased, but the bias is economically small. Thus, there is no evidence that users of these reports should be concerned about bias. Revisions to COF estimates are not random and exhibit persistence, suggesting when revisions are made subsequent similar types of revisions tend to follow. However, on average, market analysts do not correctly anticipate revisions. Thus, if analysts' prerelease estimates are different from the initial COF report, this does not signal any useful information about future probable COF revisions. [EconLit citations: Q130, D840.] © 2004 Wiley Periodicals, Inc. Agribusiness 20: 363–374, 2004.
Technical knowledge for food product innovation in Thailand
Authors: Siriwongwilaichat Prasong , Winger Ray J.
Published: July 2004

Rapid, effective product design and launch requires advanced technical skills. As new knowledge is expanding at an exponential rate, it is critical that food technologists keep up to date with international scientific developments. Interviews with 62 food‐processing companies, 43 technical information providers, and three focus groups with technical food product developers were conducted in this study. The main technical knowledge sources used by Thai food‐manufacturing companies to support the development of new branded food products have been identified. Thai food companies' internal technical staff were the major source of technical knowledge for food product development. Food ingredient suppliers were the most important external provider of knowledge to these technical staff. The main technical information provided included ingredient specifications, food recipes, consultancy, and product testing. New products that were radically innovative required greater input from external technical knowledge sources than products that were incrementally innovative. [EconLit citations: L150, L290, L660.] © 2004 Wiley Periodicals, Inc. Agribusiness 20: 233–252, 2004.
Farmer‐owned brands?
Authors: Hayes Dermot J. , Lence Sergio H. , Stoppa Andrea
Published: July 2004

This report lays out the economic arguments in favor of the establishment of farmer‐owned brands in Midwestern agriculture and presents four case studies based on successful efforts in this area in the European Union and the United States. The case studies involve Parma Ham, Brunello di Montalcino wine, Vidalia onions, and a third‐party verification organization. The case studies show that these brands can be profitable for farmers, and emphasize the importance of restricting the supply of any successful brand. One of the case studies shows that this type of supply control can run afoul of antitrust regulations. [EconLit citations: Q130, Q180, R580.] © 2004 Wiley Periodicals, Inc. Agribusiness 20: 269–285, 2004.
Gibbs energy approach for aqueous processes with HF, HNO3, and CO2CaCO3
Authors: Salminen Justin , Kobylin Petri , Liukkonen Simo , Chiavone‐Filho Osvaldo
Published: July 2004

Chemical thermodynamic calculations were used to represent vapor–liquid equilibria and chemical equilibria for aqueous systems with HF, HNO3, and CO2H2OCaCO3 solutions. The entropy production related to the dissolution reaction of calcite was calculated using multiphase thermodynamics and experiments carried out in this work. Modern simulation methods combined with experiments provide a useful tool for the research and design of new processes as well as evaluating changes in the operational conditions of chemical processes. These methods are used to study metallurgical, pulp, and paper industrial processes that involve the presented aqueous solutions. © 2004 American Institute of Chemical Engineers AIChE J, 50: 1942–1947, 2004
Removal of a model protein foulant from metal surfaces
Authors: Xin Hong , Chen Xiao Dong , Özkan Necati
Published: July 2004

Using precoated whey protein concentrate gel films as a model milk protein fouling material, the removal kinetics from the inner surface of a stainless steel tube were determined continuously and noninvasively by a rapid UV spectrophotometric method. The influences of temperature, flow velocity, and the amount of fouling on the cleaning behavior were evaluated. For the first time, a cleaning model combining polymer dissolution and boundary layer mass transfer has been used to describe the cleaning process. It is suggested that the disengagement of protein molecules from the swollen gel–solution interface and the transfer of these disengaged protein molecules into the bulk cleaning solution are the rate‐limiting steps in the range of conditions examined. The experimental results agree with the predictions of the cleaning model. The application of the current cleaning model to milk protein and whey protein fouling systems reported by various researchers is also discussed. 2004 American Institute of Chemical Engineers AIChE J, 50:1961–1973, 2004
Poly(phenylene ether)/epoxy thermoset blends based on anionic polymerization of epoxy monomer
Authors: Prolongo Silvia G. , Cabanelas J. C. , Fine T. , Pascault Jean‐Pierre
Published: July 2004

Low molar mass poly (phenylene ether) (LMW‐PPE) with phenol‐reactive chain ends was used as modifier of epoxy thermoset. The epoxy monomer was diglycidylether of bisphenol A (DGEBA), and several imidazoles were used as initiators of anionic polymerization. The curing and phase separation processes were investigated by different techniques: Differential Scanning Calorimetry, Size Exclusion Chromatography, and Light Transmission measurements. The final morphology of blends was observed by Environmental Scanning Electron Microscopy and Transmission Electron Microscopy. The epoxy network is obtained by imidazole initiated DGEBA homopolymerization. Initial LMW‐PPE/DGEBA mixtures show an UCST behavior with cloud point temperatures between 40 and 90°C. PPE phenol end‐groups can react with epoxy, leading to a better interaction between phases. The curing mechanism and phase separation process are not influenced by the chemical structure of initiators, except when reactive amine groups are present. The phase inversion is observed at 30 wt % of PPE. The mixtures with amine‐substituted imidazole present important differences in the initial miscibility and curing process interpreted in terms of fast room temperature amine‐epoxy reaction during blending. Final domain size is affected by this prereaction. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2678–2687, 2004
Predicting solubility and permeation properties of organic solvents in Viton glove material using Hansen's solubility parameters
Authors: Evans Katherine M. , Hardy James K.
Published: July 2004

A model based on a combination of the solubility parameters of Hansen and the polymer solution theory of Flory–Rehner was used to predict the solubility and permeation properties of organic solvents in Viton polymeric glove material. To test the validity of the model, weight gain data were collected for 32 organic solvents versus Viton. Samples were exposed for periods of 2 to 12 weeks until each glove sample had achieved a stable, equilibrium weight. Using a nonlinear least‐squares regression, the three‐dimensional solubility parameter was determined for Viton to be as follows: dispersion = 15.38, polar = 10.49, and hydrogen bonding = 2.47. Breakthrough times, lag times, and steady‐state permeation rates for the solvents verses Viton were also determined and combined with results obtained from the literature. A high level of correlation was observed between the model and the properties evaluated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2688–2698, 2004
Effect of ammonia on madder‐dyed natural protein fiber
Authors: Montazer M. , Parvinzadeh M.
Published: July 2004

Of all the beautiful reds in nature, the only one vegetable source of good dyes ever discovered by man is madder. In this research natural protein fibers (i.e., wool yarns) were dyed with madder and then treated with different ammonia solutions. A UV–visible spectrophotometer was used to measure the absorbency of the remaining ammonia solution. The absorption curves showed the absorption transfer to the visible region. FTIR spectroscopy studies indicated that the changes in intensity at the peaks occurred when the madder‐dyed yarns were treated with ammonia solutions. The results of color measurement in the CIELAB system showed that the darkness of samples increased with an increase in the ammonia percentage in the solution. The vertical wicking test was also carried out on the madder‐dyed yarns and the ammonia‐treated samples. The results showed that the ammonia treatment causes a decrease in the wicking rate. A change of color was observed on the dyed samples when wash‐fastness tests were carried out. The results of light‐fastness tests showed more fading of the madder‐dyed yarns after ammonia treatment. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2704–2710, 2004
The dispersion behavior of clay particles in poly(L‐lactide)/organo‐modified montmorillonite hybrid systems
Authors: Nam Pham Hoai , Fujimori Atsuhiro , Masuko Toru
Published: July 2004

Hybrids of poly(L‐lactide)/organoclay (PLACHs) have been prepared via a melt‐compounding process using poly(L‐lactide) (PLLA) and three types of surface‐treated montmorillonite modified with ammonium salts (M1, trimethyl octadecyl‐; M2, dimethyl dioctadecyl‐, and M3, bis(4‐hydroxy butyl) methyl octadecyl‐ammonium). The dispersed state of the clay particles in the PLLA matrix was examined by use of wide‐angle X‐ray diffraction, transmission electron microscopy, and polarizing optical microscopy. On melt‐compounding PLLA and two organoclays (M1, M2) modified with the surfactants both carrying homogenous alkyl chains, we obtained intercalated hybrids with relatively uniform dispersion of nanometer‐sized clay particles. On the other hand, the organoclay (M3) modified with a surfactant carrying alkyl chains end‐capped with hydroxyl groups yielded the composite with flocculated particles. The flocculation of the particles originates from the hydrogen bonding among the hydroxyl groups of the component surfactant, those of the clay edge and those of both ends of PLLA chains. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2711–2720, 2004
Localization of Web design: An empirical comparison of German, Japanese, and United States Web site characteristics
Authors: Cyr Dianne , Trevor‐Smith Haizley
Published: July 2004

To explore issues of user interface design and experience, including culturally preferred design elements, a study was conducted analyzing sites in Germany, Japan, and the United States (30 municipal sites in each country). Design elements considered are use of symbols and graphics, color preferences, site features (links, maps, search functions, and page layout), language, and content. Significant modal differences were found in each of the listed categories. Outcomes from the study are used to discuss future research directions in the areas of experience design and localization.
Vorgespannte Verbundtragwerke Isarbrücke Oberföhring auf dem Prüfstand
Authors: Seidl Günter , Grassl Hans , Gärtner Karlheinz
Published: July 2004

Verbundtragwerke mit Längs‐ und Quervorspannung zählen zu den Besonderheiten im Brückenbau. Die Isarbrücke Oberföhring im Zuge des Föhringer Rings aus dem Jahr 1960 ist ein Beispiel für die Kombination einer Spanngliedvorspannung gekoppelt mit einer Vorspannung durch Abstapeln. Das Tragwerk wurde im Hinblick auf den Materialeinsatz sehr wirtschaftlich konstruiert und ist nach mehr als 40 Jahren trotz der hohen Verkehrsbelastung in einem bemerkenswert guten Zustand. Die Ergebnisse der Hauptprüfung und die Ursachen der dabei dennoch festgestellten Schäden werden dargestellt. Eine Auswertung der Bemessung und des Tragverhaltens zeigt, mit welchen Mitteln die beachtliche Schlankheit des Hauptfelds unter geringem Materialeinsatz erzielt werden konnte. Hierin spielt die Vorspannung eine zentrale Rolle.
Erweiterung der Technischen Biegelehre ‐ Teil 2
Authors: Krebs Albert , Schnell Jürgen , Hartung Bernhard
Published: July 2004

Im ersten Teil der Veröffentlichung [1] wurden die Bedingungsgleichungen der Erweiterten Technischen Biegelehre (ETB) hergeleitet und deren Lösbarkeit nachgewiesen. Der hier vorliegende zweite Teil zeigt, ausgehend von der Ermittlung der Spannungsresultanten, die iterative Lösung der Bedingungsgleichungen. An zwei Stahlbetonbalken (mit/ohne Vorspannung) werden die mit der ETB berechneten Verzerrungszustände den in der Realität auftretenden Verzerrungen gegenübergestellt. Eine mögliche Anwendung der Theorie wird an einer durch einen Betonierfehler geschädigten Brücke vorgestellt.
Tragverhalten und Bemessung von Befestigungen mit Verbunddübeln unter Zugbeanspruchung ‐ Teil 1
Authors: Eligehausen Rolf , Appl Jörg J. , Lehr Bernhard , Meszaros Juraj , Fuchs Werner
Published: July 2004

Im Bauwesen werden in zunehmendem Maße Dübel zur Einleitung von Lasten in den erhärteten Beton eingesetzt. Vor allem Befestigungssysteme auf der Grundlage chemischer Mörtel werden vermehrt verwendet.

In diesem Beitrag werden das Tragverhalten und die Bemessung von Befestigungen mit Verbunddübeln unter Zugbeanspruchung vorgestellt. Das Bemessungsmodell beruht auf dem CC‐Verfahren [1] und berücksichtigt die wesentlichen Einflußparameter auf die Bruchlast mit ausreichender Genauigkeit.
Holz‐Beton‐Verbundbauweise in der Praxis
Authors: Rug Wolfgang , Lißner Karin
Published: July 2004

Ein Verbund zwischen Beton und Holz ist eine wirkungsvolle Lösung für Brücken in Holz und Holzbalkendecken. Solche Verbundkonstruktionen haben eine höhere Steifigkeit und Tragfähigkeit. Gleichzeitig gibt es weitere Vorteile, so z. B. bei Holz‐Beton‐Decken einen hohen Feuerwiderstand und einen verbesserten Schallschutz. Der Beitrag berichtet über den Entwicklungsstand der Anwendung des Verbundes von Holz und Beton und geeigneter Holz‐Beton‐Verbindungstechniken in der Holzbaupraxis.
Putative implication of α‐amylase loop 7 in the mechanism of substrate binding and reaction products release
Authors: André G. , Tran V.
Published: July 2004

α‐Amylases are widespread endo‐enzymes involved in the hydrolysis of internal α‐(1,4) glycosidic linkages of starch polymers. Molecular modeling of amylose–amylase interactions is a step toward enzymatic mechanism understanding and rational design of new enzymes. From the crystallographic complex of barley α‐amylase AMY2‐acarbose, the static aspects of amylose–amylase docking have been characterized with a model of maltododecaose (DP12) (G. André, A. Buléon, R. Haser, and V. Tran, Biopolymers 1999, Vol. 50, pp. 751–762; G. André and V. Tran, Special Publication no. 246 1999, The Royal Society of Chemistry, H. J. Gilbert, G. J. Davies, B. Henrissat, and B. Svensson, Eds., Cambridge, pp. 165–174). These studies, consistent with the experimental subsite mapping (K. Bak‐Jensen, G. André, V. Tran, and B. Svensson, Journal of Biological Chemistry, to be published), propose a propagation scheme for an amylose chain in the active cleft of AMY2. The topographical overview of α‐amylases identified loop 7 as a conserved segment flanking the active site. Since some crystallographic experiments suspected its high flexibility, its putative motion was explored through a robotic scheme, an alternate route to dynamics simulations that consume CPU time. The present article describes the characteristics of the flexibility of loop 7: location and motion in AMY2. A back‐and‐forth motion with a large amplitude of more than 0.6 nm was evaluated. This movement could be triggered by two hinge residues. It results in the loop flipping over the active site to enhance the docking of the native helical substrate through specific interactions, it positions the catalytic residues, it distorts the substrate towards its transition state geometry, and finally monitors the release of the products after hydrolysis. The residues involved in the process are now rational mutation points in the hands of molecular biologists. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
Structural properties and photophysical behavior of conformationally constrained hexapeptides functionalized with a new fluorescent analog of tryptophan and a nitroxide radical quencher
Authors: Venanzi Mariano , Valeri Alessandro , Palleschi Antonio , Stella Lorenzo , Moroder Luis , Formaggio Fernando , Toniolo Claudio , Pispisa Basilio
Published: July 2004

The influence of the conformational properties on the photophysics of two de novo designed hexapeptides was studied by spectroscopic measurements (ir, NMR, steady‐state, and time resolved fluorescence) and molecular mechanics calculations. The peptide sequences comprise two nonproteinogenic residues: a β‐(1‐azulenyl)‐L‐alanine (Aal) residue, obtained by formally functionalizing the Ala side chain with the azulene chromophore, and a Cα‐tetrasubstituted α‐amino acid (TOAC), incorporating a nitroxide group in a cycloalkyl moiety. Aal represents a new fluorescent, quasi‐isosteric Trp analog and TOAC a stable radical species, frequently used as a paramagnetic probe in biochemical studies. The peptide chains differ in the sequence position of the two probes and are heavily based on Aib (α‐aminoisobutyric acid) residues to generate conformationally restricted helical structures, as confirmed by both spectroscopic and computational results. The conformationally controlled, excited state interactions, determining the photophysical relaxation of the Aal*/TOAC pair, are also discussed. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
Morphologies and conformation transition of lentinan in aqueous NaOH solution
Authors: Zhang Xufeng , Zhang Lina , Xu Xiaojuan
Published: July 2004

Molecular morphologies and conformation transition of lentinan, a β‐(1→3)‐D‐glucan from Lentinus edodes, were studied in aqueous NaOH solution by atomic force microscopy (AFM), viscometry, multiangle laser light scattering, and optical rotation measurements. The results revealed that lentinan exists as triple‐helical chains and as single random‐coil chains at NaOH concentration lower than 0.05M and higher than 0.08M, respectively. Moreover, the dramatic changes in weight‐average molecular weight Mw, radius of gyration 〈s2〉1/2, intrinsic viscosity [η], as well as specific optical rotation at 589 nm [α]589 occurred in a narrow range of NaOH concentration between 0.05 and 0.08M NaOH, indicating that the helix–coil conformation transition of lentinan was carried out more easily than that of native schizophyllan and scleroglucan, and was irreversible. For the first time, we confirmed that the denatured lentinan molecule, which was dissolved in 0.15M NaOH to be disrupted into single coil chains, could be renatured as triple helical chain by dialyzing against abundant water in the regenerated cellulose tube at ambient temperature (15°C). In view of the AFM image, lentinan in aqueous solution exhibited the linear, circular, and branched species of triple helix compared with native linear schizophyllan or scleroglucan. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
Binding H2, N2, H−, and BH3 to Transition‐Metal Sulfur Sites: Synthesis and Properties of [Ru(L)(PR3)(‘N2Me2S2’)] Complexes (L=η2‐H2, H−, BH3; R=Cy, iPr)
Authors: Sellmann D. , Hille A. , Heinemann F. W. , Moll M. , Reiher M. , Hess B. A. , Bauer W.
Published: July 2004

The reactions of [Ru(N2)(PR3)(‘N2Me2S2’)] [‘N2Me2S2’=1,2‐ethanediamine‐N,N′‐dimethyl‐N,N′‐bis(2‐benzenethiolate)(2−)] [1 a (R=iPr), 1 b (R=Cy)] and [μ‐N2{Ru(N2)(PiPr3)(‘N2Me2S2’)}2] (1 c) with H2, NaBH4, and NBu4BH4, intended to reduce the N2 ligands, led to substitution of N2 and formation of the new complexes [Ru(H2)(PR3)(‘N2Me2S2’)] [2 a (R=iPr), 2 b (R=Cy)], [Ru(BH3)(PR3)(‘N2Me2S2’)] [3 a (R=iPr), 3 b (R=Cy)], and [Ru(H)(PR3)(‘N2Me2S2’)]− [4 a (R=iPr), 4 b (R=Cy)]. The BH3 and hydride complexes 3 a, 3 b, 4 a, and 4 b were obtained subsequently by rational synthesis from 1 a or 1 b and BH3⋅THF or LiBEt3H. The primary step in all reactions probably is the dissociation of N2 from the N2 complexes to give coordinatively unsaturated [Ru(PR3)(‘N2Me2S2’)] fragments that add H2, BH4−, BH3, or H−. All complexes were completely characterized by elemental analysis and common spectroscopic methods. The molecular structures of [Ru(H2)(PR3)(‘N2Me2S2’)] [2 a (R=iPr), 2 b (R=Cy)], [Ru(BH3)(PiPr3)(‘N2Me2S2’)] (3 a), [Li(THF)2][Ru(H)(PiPr3)(‘N2Me2S2’)] ([Li(THF)2]‐4 a), and NBu4[Ru(H)(PCy3)(‘N2Me2S2’)] (NBu4‐4 b) were determined by X‐ray crystal structure analysis. Measurements of the NMR relaxation time T1 corroborated the η2 bonding mode of the H2 ligands in 2 a (T1=35 ms) and 2 b (T1=21 ms). The H,D coupling constants of the analogous HD complexes HD‐2 a (1J(H,D)=26.0 Hz) and HD‐2 b (1J(H,D)=25.9 Hz) enabled calculation of the HD distances, which agreed with the values found by X‐ray crystal structure analysis (2 a: 92 pm (X‐ray) versus 98 pm (calculated), 2 b: 99 versus 98 pm). The BH3 entities in 3 a and 3 b bind to one thiolate donor of the [Ru(PR3)(‘N2Me2S2’)] fragment and through a B‐H‐Ru bond to the Ru center. The hydride complex anions 4 a and 4 b are extremely Brønsted basic and are instantanously protonated to give the η2‐H2 complexes 2 a and 2 b.
De novo Metallonucleases Based on Helix–Loop–Helix Motifs
Authors: Rossi Paola , Tecilla Paolo , Baltzer Lars , Scrimin Paolo
Published: July 2004

Three new 42‐mer peptides (PR I–III) designed to fold into a hairpin helix–loop–helix motif have been prepared. In the peptide sequence two (PR II–III) or four (PR I) copies of an unnatural amino acid bearing a triazacyclononane metal‐ion binding site (ATANP) have been inserted in appropriate positions to allow the ligand subunits to face each other either within the same helix or between the two helices of the hairpin motif. Circular dichroism (CD) studies in solution have shown that the apopeptides adopt a well‐defined helix–loop–helix tertiary structure that dimerizes in solution at concentrations above 200 μM to form a four‐helix bundle. However, the helical content is strongly dependent on pH and metal‐ion binding. Both protonation of the amines of the triazacyclononane units present in the ATANP lateral arm and complexation with ZnII ions cause a significant decrease of the helical content of the sequences. The ZnII complexes of the three peptides catalyze the transesterification of the RNA model substrate 2‐hydroxypropyl‐p‐nitrophenyl phosphate (HPNP) with different efficiency. The best catalyst appears to be PR I–4 ZnII, that is, the peptide incorporating four ATANP units. Michaelis–Menten saturation kinetics allowed us to estimate that substrate fully bound to the catalyst reacts 380 times faster than in its absence. The kinetic evidence suggests cooperativity between (at least two) metal ions: one activating the nucleophilic species (directly or indirectly) and the other facilitating nucleophilic attack by coordination of the phosphate.
Stereoselective Synthesis of (+)‐Nephrosteranic Acid, (+)‐trans‐Cognac Lactone, and (+)‐trans‐Whisky Lactone using a Chiral Cyclohexadienyl Ti Compound
Authors: Schleth Florian , Vogler Thomas , Harms Klaus , Studer Armido
Published: July 2004

We present the stereoselective transfer of cyclohexadienyl from 3‐metalated 1,4‐cyclohexadienes to various aldehydes. Lewis‐acid‐mediated “allylation” of aldehydes by treatment with 3‐silylated and 3‐stannylated 1,4‐cyclohexadienes could not be achieved with high diastereoselectivity. In contrast, cyclohexadienyl titanium compounds reacted with both aliphatic and aromatic aldehydes with good‐to‐excellent diastereoselectivities. Reaction of a chiral TADDOL‐derived (TADDOL, 2,2‐dimethyl‐α,α,α′,α′‐tetraphenyl‐1,3‐dioxolandimethanol) cyclohexadienyl Ti derivative with various aldehydes led to the corresponding homoallylic alcohols with excellent diastereo‐ and enantioselectivities. Lower selectivities were obtained with chiral B‐cyclohexadienyldiisopinocampheylborane. The 1,3‐cyclohexadienes are very useful building blocks for the preparation of biologically important γ‐butyrolactones. Short efficient syntheses of (+)‐nephrosteranic acid, (+)‐trans‐whisky lactone, and (+)‐trans‐cognac lactone by desymmetrization of 1,4‐cyclohexadiene are described.
Determination of binding constants of cyclodextrin inclusion complexes with amino acids and dipeptides by potentiometric titration
Authors: Kahle Claudia , Holzgrabe Ulrike
Published: July 2004

Cyclodextrins are well known for their ability to separate enantiomers of drugs, natural products, and other chiral substances using HPLC, GC, or CE. The resolution of the enantiomers is due to the formation of diastereomeric complexes between the cyclodextrin and the pairs of enantiomers. The aim of this study was to determine the binding constants of the complexes between α‐ and β‐cyclodextrin and the enantiomers of a series of aliphatic and aromatic amino acids, and dipeptides, using a potentiometric titration method. The results of this method are compared to other methods, and correlated to findings in cyclodextrin‐modified capillary electrophoresis and possible complex structures. Potentiometric titration was found to be an appropriate tool to determine the binding constants of cyclodextrin inclusion complexes. Chirality 16:509–515, 2004. © 2004 Wiley‐Liss, Inc.
Free circulating soluble CD52 as a tumor marker in chronic lymphocytic leukemia and its implication in therapy with anti‐CD52 antibodies
Authors: Albitar Maher , Do Kim‐Anh , Johnson Marcella M. , Giles Francis J. , Jilani Iman , O'Brien Susan , Cortes Jorge , Thomas Deborah , Rassenti Laura Z. , Kipps Thomas J. , Kantarjian Hagop M. , Keating Michael
Published: July 2004

BACKGROUND

The CD52 antigen is a glycoprotein anchored on the cell membrane of mature B and T lymphocytes, monocytes, and eosinophils. Alemtuzumab (CAMPATH‐1H; anti‐CD52) is currently approved for the treatment of patients with refractory chronic lymphocytic leukemia (CLL). The authors investigated the possibility that CD52 may be shed from cells and, once soluble, may bind to injected alemtuzumab, forming immune complexes.

METHODS

The authors used Western blot analysis, immunoprecipitation, and enzyme‐linked immunoadsorbent assay to investigate the presence of soluble CD52 (sCD52) in the plasma specimens of 117 patients with CLL. They also used in vitro mixing experiments to examine the ability of sCD52 to compete with cells and sequester therapeutic alemtuzumab.

RESULTS

The authors detected high levels of sCD52 in the plasma specimens of patients with CLL. sCD52 can compete with cells in vitro for binding to alemtuzumab, and can form complexes in patients receiving alemtuzumab. Plasma levels of sCD52 were found to be correlated (r)with Rai stage (P = 0.0001), β‐2‐microglobulin (β‐2M) levels (P = 0.00002), soluble CD23 levels (r = 0.42, P < 0.001), and immunoglobulin mutation status (P = 0.003). In the multivariate analysis adjusted for β‐2M level, patients with sCD52 levels > 2336 nM/L had a nearly 4‐fold increase in risk of death. Higher levels of plasma alemtuzumab were achieved when levels of sCD52 were lower.

CONCLUSIONS

These data not only demonstrated that sCD52 was detectable and useful in the staging and monitoring of patients with CLL, but also showed that sCD52 formed immune complexes with alemtuzumab and may influence the efficacy and toxicity of alemtuzumab therapy. Cancer 2004. © 2004 American Cancer Society.
Solution of clamped rectangular plate problems
Authors: Taylor Robert L. , Govindjee Sanjay
Published: July 2004

In this brief note, we present an efficient scheme for determining very accurate solutions to the clamped rectangular plate problem. The method is based upon the classical double cosine series expansion and an exploitation of the Sherman–Morrison–Woodbury formula. If the cosine expansion involves M terms and N terms in the two plate axes directions, then the classical method for this problem involves solving a system of (MN) × (MN) equations. Our proposal reduces the problem down to a system of well‐conditioned N × N equations (or M × M when M < N). Numerical solutions for rectangular plates with various side ratios are presented and compared to the solution generated via Hencky's method. Corrections to classical results and additional digits for use in finite‐element convergence studies are given. As an application example, these are used to show the rate of convergence for thin plate finite‐element solutions computed using the Bogner–Fox–Schmit element. Copyright © 2004 John Wiley & Sons, Ltd.
An efficient shape‐preserving curve fitting technique for complex structures
Authors: Hyun Seokjeong , Kim Cheol
Published: July 2004

An efficient curve fitting technique has been developed to preserve the shape of complex structures. A shape‐preserving curve fitting technique is frequently used in a mesh generation or a shape optimization process. Perturbations during the curve fitting process often appear if the shape of a structure is complex or if the data points are positioned irregularly. The proposed technique represents more precise and smoother surfaces than using conventional B‐spline curves. Several comparisons are made and results show the superiority of the proposed technique over B‐spline curves. Copyright © 2004 John Wiley & Sons, Ltd.