bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detection of Radicals Generated by Strong Oxidants in Acidic Media
Authors: Ragnar M. , Eriksson T. , Reitberger T. 
Published: October 2004

Summary
A new method to study superoxide and hydroxyl radicals in aqueous solution in the pH range 1 to 6 is described and critically evaluated. The method primarily detects superoxide, which reacts with tetranitromethane (TNM) by reductive cleavage. The strongly coloured nitroform anion (ε350nm = 15000M−1 cm−1) formed, is easily measured in a spectrophotometer or in a stopped-flow equipment. Hydroxyl radicals are measured indirectly. In a first step the hydroxyl radical reacts with iso-propyl alcohol to give acetone and superoxide. The superoxide formed is then in a second step detected with TNM. The TNM-method was primarily designed to monitor the radical formation under ozone bleaching conditions, but it is also applicable in acidic hydrogen peroxide.
The Investigation of Hydration Processes in Horse Chestnut (Aesculus hippocastanum L.) and Pine (Pinus silvestris L.) Bark and Bast Using Proton Magnetic Relaxation
Authors: Haranczyk H. , Weglarz W. P. , Sojka Z. 
Published: October 2004

Summary
The proton free induction decay (FID) was shown to be effective in monitoring of hydration and the water soluble extractive fraction in horse chestnut (Aesculus hippocastanum, L.) and pine (Pinus silvestris, L.) bark and bast. The signal from the first bound water layers was separated from the whole liquid signal (L) and at low hydration the liquid signal from the stable sealed bark pores was detected. The liquid-to-solid (L/S) signal ratio as a function of relative mass increase (∆m/m0) was proposed as a convenient method to evaluate the relative mass of water, necessary to dissolve the whole soluble proton pool (∆M/m0), the relative mass contribution of solid proton component (p0 in absence of water soluble fraction or pS0 in presence of water soluble fraction), the saturation concentration of the water soluble fraction (cs) and the effective (scaled to water) proton density of solid protons (βs). The measurement of the absolute (in arbitrary units) proton signal versus relative mass increase yielded additionally the effective proton density water soluble proton fraction in solid (βcu) and in liquid (βcd) phase. For the system containing the soluble proton fraction (horse chestnut bast), the values of the parameters obtained from L/S versus ∆m/m0 dependence were compared with the calculated (or fitted) values obtained from the results of the absolute (in arbitrary units) NMR signal measurements.
The effective proton densities (βs) were: 0.33 for pine bark, 0.31 for horse chestnut bark and 0.20 for horse chestnut bast, which suggests the presence of paramagnetic impurities in the solid matrix. The presence of various paramagnetic species was further confirmed by ESR spectroscopy.
For horse chestnut bast, in which a water soluble extractive fraction is present, the saturation concentration (cs) of the water soluble fraction was 0.64. The contribution of the water soluble fraction was 0.324 of the total dry mass and the relative proton density βcu = 0.55 (in the solid phase). The contribution of non-removable liquid fraction was 0.004 of the total dry mass.
The proton relaxation experiment did not directly reveal a percolation threshold, however, the dehydration extended below the removal of the loosely bound mobile water fraction.
Influence of Degree of Polymerization of Cellulose and Hemicellulose on Strength Loss in Fire-Retardant-Treated Southern Pine
Authors: Sweet M.S. , Winandy J.E. 
Published: October 2004

Summary
Southern pine boards, both untreated and treated with a fire retardant, were exposed to either a room temperature or high temperature (66°C (150°F)) environment. Strength properties were measured after 1 and 1-1/2 years of exposure, respectively. The degree of polymerization and the chemical composition of α- cellulose isolated from the exposed wood were measured. Little relationship was found between degree of polymerization and strength. However, a strong relationship was found between the amount of mannan in the α-cellulose isolated from the wood and the modulus of rupture and the work-to-maximum load of solid wood. This correlation leads to the conclusion that hemicellulose plays an important role in determining the strength of wood.
Hexamethyldisiloxane-Plasma Coating of Wood Surfaces for Creating Water Repellent Characteristics
Authors: Denes A. R. , Tshabalala M. A. , Rowell R. , Denes F. , Young R.A. 
Published: October 2004

Summary
Southern yellow pine wood surfaces were modified under cold plasma conditions in order to create water repellent characteristics. The surface chemistry of the plasma “polymerized” hexamethyldisiloxane (PHMDSO) deposited onto wood surfaces was investigated using Electron Spectroscopy for Chemical Analysis (ESCA) and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR). The presence of a crosslinked macromolecular structure, based on Si-O-Si and Si-O-C linkages was detected. Pyrolysis Mass Spectroscopy (MS) was carried out to investigate the nature of the building blocks of the plasma generated macromolecular structure. Plasma modified samples exhibited very high water contact angle values (contact angle = 130 degrees) in comparison to the unmodified samples (contact angle ≤ 15 degrees), indicating the presence of a hydrophobic surface. Atomic Force Microscopy (AFM) images, collected both from unmodified and HMDSO-plasma modified samples, indicate the progressive growth of the plasma “polymer”, resulting in the deposition of a smooth layer at 10 minutes treatment time. Differential Thermal Analysis (DTA) indicated high thermal stability of the PHMDSO.
Charged‐particle Optics
Authors: Nolen Jerry A. , Portillo Mauricio 
Published: October 2004

Abstract
The emphasis of this article is on the common fundamentals and techniques on which the wide variety of different beam‐optical devices are based. It should give the reader the necessary background to understand the principles of the actual devices described elsewhere in more advanced treatments. Along with the qualitative description of the basic building blocks of charged particle beam optics, enough selected references to monographs and research reports are given to guide the interested reader towards more in‐depth studies. Relatively few references to original research papers are given, but extensive bibliographies are included in the listed review articles and textbooks. Topics introduced include: single‐particle motion of charged particles in electric and magnetic fields, sources of charged particles, beam handling and transport, magnetic and electric deflection systems, aberrations of charged particle optical systems, and the mathematics of matrix methods for charged particle optical simulation.
Lasers, Gas
Authors: Eden J. Gary , Eichler Jürgen 
Published: October 2004

AbstractThis article reviews the characteristics of gas lasers that are chiefly responsible for their effectiveness as both scientific and industrial tool. The basic principles common to operation of all gas lasers and a few of their general properties are discussed. The lasers are categorized according to the pumping mechanisms: electron‐impact excitation (copper and gold laser, Ar‐ and Kr‐ion lasers), excitation transfer (He–Ne laser, He–Cd laser, CO2laser), reactive collision lasers (excimer laser (ArF, KrF, XeCl, XeF, F2), chemical lasers (HF, COIL)), and other lasers in the far infrared, ultraviolet, and soft X‐ray region. Selected applications of pulsed and continuous gas lasers are presented in material processing, marking and laser evaporation, microlithography, photochemical processing, stereolithography, and medicine.
Lasers, Industrial Use of
Authors: Roessler David M. , Steen Wiliam M. 
Published: October 2004

AbstractLasers are capable of generating large and controllable quantities of optical energy and delivering it at intensities sufficient to produce permanent changes in materials. This new form of industrial energy has led to a wide range of laser‐based manufacturing processes, such as cutting, welding, surface treatment, bending, cleaning, rapid prototyping, direct casting, and so on. Although these form the focus of this section, it must be noted that there are many other industrial applications that are not covered here, ranging from communications and compact disc players to medicine and metrology. Although laser‐materials processing has developed and grown rapidly in the last few decades, it is still far from being a mature technology. New lasers continue to be developed as do new applications.
Diodes, Light‐emitting
Authors: Gardner Nathan F. , George Craford M. , Steranka Frank M. 
Published: October 2004

Abstract
A light‐emitting diode (LED) is a semiconductor device that emits monochromatic ultraviolet, visible, or infrared electromagnetic radiation when an electric current is passed through it. The semiconductor material is a compound or alloy of elements from columns III and V of the periodic table. Light‐emitting diodes are compact, mechanically rugged, energy efficient, are of low voltage, and have long operating lifetimes. For colored lighting applications, the efficiency of LEDs far exceeds that of filtered incandescent sources and they are becoming the dominant technology. LEDs are widely used as indicator lights, for backlighting small displays in electronic equipment, in exterior and interior lighting of automobiles, in large‐area full‐color displays, and for data communication. LEDs will be used for general white‐light illumination purposes to the extent that the energy efficiency improves and higher‐power, higher‐flux devices become available.
Optical Components and Systems
Authors: Litfin Gerd , Schuhmann Rainer 
Published: October 2004

AbstractThis article gives an overview of geometrical optics and includes the most important formulas as well as a few optical systems of general interest.It describes the main optical components such as lenses, mirrors, plane plates, prisms, fibers, and thin films and their influence on light beams as light propagation and polarization. The principles of reflection and refraction are discussed as well as the optical imaging based on first‐order optics. The basic formulas are given.The discussion on plano‐optics considers the spectral properties of filters and prisms, the change of image orientation by a single prism and prism systems, beam splitting, and polarization effects due to birefringence of crystal components. Total internal reflection can guide light in optical fibers. Different fiber types are described.Besides single components as best‐form lenses and doublets, only multielement optical systems can meet the requirements of different imaging applications. Therefore, a selection of well‐known optical systems considering their main properties is described. This includes camera lenses, microscopes, and more sophisticated optical systems as well as a short side‐glance on the requirements of interferometers that cannot be described by the geometrical optics approach.Furthermore, a section on optical bench systems summarizes the necessary support of optics by mechanical components. This includes bench profiles and structural systems using the micro bench.
Optical Instrumentation
Authors: Hoeschen Dietmar , Mirandé Werner 
Published: October 2004

AbstractOptical instrumentation is based on phenomena caused by optical radiation. In this article, optical radiation is limited to a wavelength range between 200 nm and 50 µm. After a short survey about the historical development of optical instrumentation, phenomena resulting from the various characteristics of optical radiation, as for instance, a wave or a particle, are considered. Based on the wavelength character, optical instrumentation used for interferometry, colorimetry, spectroscopy, diffraction, imaging, and optical frequency standards is treated. The interaction of optical radiation with matter is used in refractometry, in polarimetry, for studying matter with ultrashort pulses of radiation, and for processing matter with radiation of high‐energy density. Finally, the particle character is considered to be used for fields such as radiometry and energy conversion.
Optical and Laser Scanning Technology
Authors: Beiser Leo 
Published: October 2004

Abstract
This article consolidates optical and laser scanning technology and its utilization. The dominant scanning devices and techniques are appraised, including the polygon and holographic scanners, galvanometer and resonant scanners, fast steering mirrors, acousto‐optic and electro‐optic deflectors, and new agile beam steering methods. Also addressed are their application, classification, architecture, symmetry factors, image rotation, duty cycle, scanned resolution, optical power transfer, and cross‐scan error reduction.
Two complementary fields are presented: (Active) Laser Scanning and (Passive) Remote Sensing. While scanning devices may appear interchangeable, significant distinctions relate to the filling of their optical apertures and the use of spectrally dispersive optics. Laser scanning, having a controlled intensity distribution, projects moving illumination on very small portions of an area with functionally coherent radiation, allowing the use of diffractive optics. In contrast, remote sensing transfers spectrally broad radiation scattered from a distant object field, imaged and collected through a scanning aperture that directs the sampled radiation to a fixed detector. The scanner, intimately associated with its objective lens, is developed as oriented within a conjugate optical imaging system. Active laser radiation is thereby transferred selectively to its image. In passive sensing, ray directions are reversed, representing the conjugate transfer of radiation from remote object points back to the detector.
Linear Optics
Authors: Dorsel Andreas 
Published: October 2004

AbstractThis article gives a condensed overview of the key areas of linear optics, addressing fundamental aspects of light propagation and their application. After first principles like the speed of light and the laws of reflection and refraction, as well as the Fresnel formulas for transmission and reflection, total internal reflection, and linear absorption, geometric optics is briefly covered with the basic descriptions of imaging using simple mirrors and lenses. As examples of simple optical instruments, the single‐lens eye, the magnifier and microscope, as well as astronomical and terrestrial telescopes are included. Subsequently, phase‐dependent phenomena like interference and diffraction are described, including examples of a few basic cases that can be used to address more complex cases. Anisotropic media and polarization effects are covered next, including brief notes on electro‐optic, magneto‐optic, and acousto‐optic effects. Finally, examples of recent developments are described as an outlook to contemporary optics work.
Spectrometers,X‐ray
Authors: Markert Thomas H. , Förster Eckhart 
Published: October 2004

AbstractX‐ray spectrometers are used in many fields of pure and applied science as well as in industry. They are employed to investigate cosmic and laboratory high‐temperature plasmas where a high spectral resolution in the emission spectra is required. Commercial X‐ray spectrometers register X‐ray fluorescence of a sample under X‐ray irradiation or electron bombardment. In this case, registration of a wide spectral range with moderate resolution is performed to obtain the elemental composition of a sample.The main experimental parameters of a spectrometer are its resolving power, sensitivity, and breadth of spectral coverage. Dispersive spectrometers that use X‐ray crystal diffraction to widen the incident spectrum have great advantages in spectral resolution. To raise their sensitivity, different X‐ray optics such as grazing incident mirrors, polycapillaries, bent gratings, or bent crystals are implemented. Nondispersive spectrometers that convert the energy of an incident X ray into a number of “particles” (electron–hole pairs, electron–ion pairs, phonons, etc.) have a moderate spectral resolution, good sensitivity, and wide breadth of spectral coverage. Recently developed microcalorimeters need a complex cryogenic system for the detector but have a competitive spectral resolution as dispersive spectrometers.
Spectroscopy, Ultrafast
Authors: Dantus Marcos , Gross Peter 
Published: October 2004

AbstractSpectroscopy studies the interaction between light and matter. Ultrafast spectroscopy involves the study of this interaction using temporally short light pulses capable of probing directly the dynamics of the system rather than its energy levels. Rapid advances in laser technology over the past decades have resulted in the generation of pulses with femtosecond time duration (1fs = 10−15 s). These lasers are being used to interrogate solids, liquids, and gases to learn about the dynamics of matter (electrons, atoms, molecules) following laser excitation. The description given here explains how an ultrashort laser pulse excites a coherent superposition of energy levels, and how this excitation can be followed in time. To date, ultrafast spectroscopy has been used to measure processes in diverse fields, for example, to measure the time it takes to break or form a chemical bond; to measure the temporal response of molecules involved in photosynthesis, or vision; and to measure the flow of charge in semiconductors. Examples of these kinds of studies illustrate this presentation.
Spectrometers, Ultraviolet and Visible Light
Authors: Hardwick John L. 
Published: October 2004

AbstractA wide variety of instruments exist for recording the intensity of light as a function of wavelength. In the visible and ultraviolet regions of the spectrum, these include dispersive spectrometers (based on gratings and prisms) and nondispersive spectrometers (usually interferometric in nature). A discussion of the main kinds of visible and ultraviolet spectrometers is given along with their advantages and drawbacks in terms of resolution, accuracy, efficiency, and ease of use. Considerations for choosing the design of an optical spectrometer are outlined, and the main aberrations associated with common optical designs are discussed.
Color Vision
Authors: Webster Michael A. 
Published: October 2004

AbstractColor provides important cues to both the nature and location of objects in our environment. Normal human color vision is trichromatic because it depends on sampling the light spectrum with three classes of cone photoreceptor maximally sensitive to short, medium, or long wavelengths. Most forms of color‐blindness are genetic and result from losses or alterations of the cone photopigments. Postreceptoral neurons sum the cone signals to form luminance‐sensitive channels and contrast them to form color‐opponent channels. Color opponency is suggested by both physiology and color appearance, though higher stages of color coding in the visual system remain unclear. Perceived color is strongly affected by adaptation to colors viewed previously and by induction from surrounding colors. These processes help normalize the response to color and contribute to color constancy for objects viewed in different lighting.
Colorimetry
Authors: Stockman Andrew 
Published: October 2004

AbstractColorimetry is concerned with the measurement and numerical specification of the color of visual stimuli. Color depends on the underlying biology of the human visual system, and in the first instance on the spectral properties of the three types of light‐sensitive cone photoreceptors in the eye. Color and color matches are trichromatic, meaning they can be specified by three variables that are linearly related to the outputs of the three cone types. The primary aim of colorimetry is to be able to specify those variables for lights of any spectral composition.
Lidar (Laser Radar)
Authors: Argall P. S. , Sica R. J. 
Published: October 2004

AbstractLidar is an active remote sensing technique similar in principle to radar, except that it utilizes light rather than radio waves. Lidar finds applications in many areas, including atmospheric and oceanic research, digital mapping, chemical and biological agent detection, speed measurement, and targeting. This chapter describes the principles of lidar and provides examples of the application of lidar in measuring the properties of the Earth's atmosphere.
Optical Metrology
Authors: deGroot Peter 
Published: October 2004

AbstractThe article reviews the optical measurement of shape, texture, geometric dimensions, and position of objects, with applications ranging from stage metrology to optical comparators. An emphasis is placed on mechanical and geometric metrology, as opposed to remote sensing. The underlying technologies rely therefore on interferometry, triangulation, and time of flight to determine distances and lengths, as well as those object features accessible to length measurement, including, for example, form and roughness.
Photonics
Authors: King Terence A. 
Published: October 2004

AbstractPhotonics concerns the generation, transmission, manipulation, and interactions of light and its applications in many varied areas in research, industry, and everyday life. This general overview of photonics draws special attention to the development of laser sources, semiconductor optics, fiber optics, and photonic techniques such as ultrafast pulse generation. The wide range of applications is reviewed with particular attention to information technology and optical communications, optical information storage, displays, sensors, and industrial applications. The rapidly growing field of applications in biophotonics and biomedical optics is also emphasized with new techniques of optical coherence tomography (OCT) and optical trapping.
Wave Optics
Authors: Dallas William J. 
Published: October 2004

Abstract

Narrowly interpreted, the term
wave optics
encompasses propagation, diffraction, interference, and thin films. Under a broader interpretation, wave optics includes those areas of optics governed by the electromagnetic wave equation. We begin with a brief review of the wave equation, which is built on the foundation of Maxwell's equations. Next is a translation of the wave equation into the propagation relations of linear systems theory. An interesting and useful aspect of propagation is the existence of helical light; light that twists as it travels. Another aspect of optical waves is its propagation from curved surfaces. We move on to interference and then diffraction. The hologram serves as an important example of interference, while the computer‐generated hologram is an example of control over diffraction. Talbot, or Fourier self‐imaging, is a stunning example of the richness of propagation from diffractive optical elements. Finally, we discuss the subject of phase retrieval from irradiance distributions on multiple surfaces.