bluuebunny/crossref_metadata_2025_split huggingface dataset:
Infrared Spectroscopy in Process Analysis
Authors: Coates John P. , Shelley Paul H. 
Published: September 2006

Abstract
Infrared (IR) instruments have been in use as important measurement and analysis tools for process monitoring and production control for more than half a century. They range in complexity from the simplest filter‐based photometers to opto‐mechanically complicated devices, such as Fourier transform infrared (FTIR) instruments. Simple nondispersive infrared (NDIR) instruments are in common use for systems where one to a few main analytes are involved. For more complex measurement situations it is necessary to record more spectral information, and often full‐spectral analyzers are used. Of the main analytical instrument techniques, IR analysis is the most versatile, where all physical forms of a sample may be considered – gas, liquids, solids and mixed phase materials. A wide range of sample handling options exists, and many of these may be adapted to either near‐line/at‐line production control or on‐line process monitoring applications. Instrumentation used within a manufacturing environment usually requires special packaging to protect the instrument from the environment, and to protect the operating environment from the instrument. This places special constraints on the way that an instrument is designed and the way that it performs. Often, it is necessary to utilize special technologies, normally not required for laboratory instruments, to meet the performance objectives. For most practical installations within a production environment it is a normal requirement for the final instrument to comply with local manufacturing and electrical safety codes. The range of applications of IR spectroscopy is extremely broad and the technique can play an important role in virtually all industries for manufacturing quality and production control, and for environmental monitoring.
Near‐Infrared Spectroscopy in Process Analysis
Authors: Goldman Don S. 
Published: September 2006

Abstract
Near infrared (NIR) is a spectroscopic method based upon the absorption of light in the wavelength region between 700 nm and 2500 nm due to vibrations of molecular functional groups in the sample. These spectral features arise from overtones and combinations of the fundamental molecular vibrations of these groups that occur in the infrared (IR) at longer wavelengths. NIR is rich with features arising from vibrations of CH, OH and NH.

NIR spectra are acquired by determining the absorbance, A, of light over a continuous range of wavelengths in spectrophotometers or at several specific wavelengths in fixed‐filter photometers. Absorbance is defined by Equation (1):

where I is the signal from the sample relative to the signal from a reference, I

o

. The reference can be an empty transmission sample cell for liquids, or it can be a broadband spectral reflector, such as a white ceramic, for reflectance measurements of solids.

Absorbance is usually linearly related to concentration, following Beer's Law (Equation 2):

where ɛ represents the molar extinction coefficient and C is the concentration of the species, and l is the optical pathlength of light through the sample. For a particular species and fixed experimental set‐up, ɛ and l are constants. Letting a constant, k = (ɛl)
−1
, then (Equation 3):

A principal advantage of process NIR over IR is the ability to use fiber optics to transmit light between the instrument and the sample over considerable distance. This permits the instrument, a potential source of ignition, to be placed in safe areas where no flammable vapors exist. Only the fiber optic probe in contact with the sample and the optical fibers that connect to the instrument need be placed in the hazardous location. A disadvantage of process NIR is the characteristics of the spectra, which are typically comprised of broad, overlapping peaks in comparison to IR spectra. This often requires the use of sophisticated data analysis methods that place additional demands upon vendors to provide stable NIR instruments and upon manufacturers to have highly‐trained staff, often at the PhD level, for calibration model development, implementation and maintenance.
X‐ray Photoelectron Spectroscopy, Paper Surface Analysis By
Authors: Pamidimukkala Krishna M. 
Published: September 2006

AbstractX‐ray photoelectron spectroscopy (XPS) also popularly known as electron spectroscopy for chemical analysis (ESCA) involves the irradiation of a solid surface in ultrahigh vacuum with monoenergetic soft X‐rays. The X‐rays cause electrons of an atom to be ejected and to be ionized as photoelectrons. The number of electrons and their kinetic energies are then measured. The energy of the emitted electron is very characteristic of the atom from which the electron originated and its environment. The XPS spectrum is a plot of the number of emitted electrons per energy interval versus their binding energies. Quantitation can be achieved either by fundamental parameter calculation or comparison with appropriate standards. In the pulp and paper industry, XPS has successfully been used to study migration of binder in coated paper, the surface chemistry of pulps and its effect on the properties of the final products; the adhesion between paper and polymer, toner or ink; and the chemical additives on the paper surface.As with most analytical instrumentation, XPS has its limitations and disadvantages and is often used in conjunction with other, complementary techniques such as SIMS (secondary ion mass spectrometry) and FTIR (Fourier transform infrared) spectroscopy for the identification of organic compounds on paper surfaces. XPS is surface sensitive which renders it useless if the underlying cause of the problem might be other than surface related. XPS provides only semiquantitative information. A more precise quantification of the elements is possible, but requires exhaustive calibration.
Elevation Modeling and Displacement Mapping using Radar Interferometry
Authors: Massonnet Didier 
Published: September 2006

Abstract
Topographic modeling consists of producing a digital description of the relief of a given area. This description is generally given on a regular grid in two coordinates. The product consists of the value of the altitude of the terrain for each position of the grid, with respect to a reference shape such as an ellipsoid (approximation of the shape of the Earth) or the geoid (shape of the potential of gravity at sea level). The grid itself is defined in a cartographic or a geographic coordinate system. Common systems include the Universal Transverse Mercator (UTM), Lambert or, alternatively, coordinates in latitude/longitude. Topographic data are used in a variety of applications, from the correction of geometric distortion in remote sensing images to the prediction of the volume of materials to be removed in public works. Their applications include military uses, such as collision avoidance for low‐flying aircraft or missiles, or civilian ones, such as optimal positioning of transmitters to cover an area for mobile communications. Radar interferometry is a promising technique for producing topographic maps on a large scale. It makes use of the very peculiar features of the images produced by synthetic aperture radar (SAR) instruments placed on board satellites. Used in differential mode, this technique can also produce a unique product: the map of the displacements which occur in a given area between two passes by a radar satellite. Again, the data can be organized as a digital file placed on a grid similar to the ones used for topographic mapping. However, in the case of displacement measurement, the useful piece of data placed on each node is the displacement experienced by the node, expressed in appropriate units of length. As for each new technique, there are a number of points to take care of before interpreting the data. The purpose of this article is to describe the radar data, both historically and technically, and to detail their two main applications in topography and displacement mapping. The main issues of the interpretation and the availability of the data are covered. Finally, we compare the performance of radar interferometry with other techniques, in both domains, and we try to outline its future.
Global Land Databases for Environmental Analyses
Authors: Loveland Thomas R. 
Published: September 2006

Abstract
Global land databases present the area, spatial extent, location, and patterns of land characteristics. Land cover, the natural and artificial materials on the land surface, is the most widely available and used land data theme, but soils and elevation global databases are also found. These land data sets are key inputs to many global and regional environmental models and provide a means to parameterize key landscape processes used in studies of climate and meteorology, atmospheric chemistry, ecological dynamics, hydrology, and resource management.
Metal Analysis, Sampling and Sample Preparation in
Authors: Deak Charles K. 
Published: September 2006

Abstract
This article deals with sampling and sample preparation for the chemical analysis of metals. It discusses the types of samples, their definitions, purposes, and requirements. Sampling of various types, shapes, and forms of metals ranging from liquid molten steel to scrap metals is described, along with ways of rendering a sample homogeneous. The various methods of making a sample suitable for the required analytical procedures are explained in the sample preparation section. This section discusses melting of samples in various types of laboratory melting furnaces and machining samples for use in all types of determinations using various techniques such as optical emission spectroscopy (OES), X‐ray fluorescence spectroscopy (XRF), atomic spectroscopy, thermal analyses, wet chemistry and so on. Discussion also centers around dissolving and fusing samples to convert them into a solution which is required by wet chemical, atomic spectroscopy, and other procedures.
Sampling and analysis of fasteners (regulated in the United States), and instances in which the sample or the analysis is or may be involved in litigation are also included.
Proximal Probe Techniques
Authors: Wiesendanger Roland 
Published: September 2006

Abstract
Proximal probe techniques are based on sharp tips which are brought within a small distance of a sample to be investigated by means of a stepper motor. The various interactions of these probe tips with the sample, which might be of mechanical, electrical, magnetic, optical or thermal origin, can be used to probe the sample's properties locally and to control the separation between tip and sample surface.
If the distance dependence of a particular type of interaction is strong, the distance control based on that interaction is very sensitive to small changes in tip–sample separation. By scanning the probe tip over the sample surface while keeping the interaction strength constant using a feedback loop, the surface contours can be followed by the tip with high accuracy. By monitoring the vertical position of the tip as a function of the lateral position, a three‐dimensional image of the sample surface is obtained. The motion of the tip both laterally and vertically with respect to the sample surface can be realized with subatomic accuracy by means of piezoelectric drives.
In contrast to electron microscopy and vacuum‐based surface analytical methods, proximal probe techniques can be operated in air and in liquids in addition to in vacuum. Therefore, proximal probe techniques offer great potential for investigations of solid–liquid interfaces or for in vivo investigations of biological specimens. Furthermore, proximal probe techniques can be operated in a wide temperature range (from millikelvin up to more than a 1000 K) and under extreme conditions (e.g. in high magnetic fields or high‐pressure conditions). The most attractive feature of proximal probe techniques is, however, that they combine ultrahigh spatial resolution (down to the atomic scale) with high‐resolution spectroscopic measurements so that detailed information about the physical, chemical or biological state of the sample can be extracted. Limiting factors are the finite size and often ill‐defined state of the probe tips and the limited information depth of proximal probe techniques. It has also found to be difficult to identify elemental species based solely on proximal probe measurements although chemical‐selective imaging even down to the atomic scale is nowadays routinely achieved.
Inductively Coupled Plasma/Optical Emission Spectrometry
Authors: Hou Xiandeng , Jones Bradley T. 
Published: September 2006

Abstract
Inductively coupled plasma/optical emission spectrometry (ICP/OES) is a powerful tool for the determination of metals in a variety of different sample matrices. With this technique, liquid samples are injected into a radiofrequency (RF)‐induced argon plasma using one of a variety of nebulizers or sample introduction techniques. The sample mist reaching the plasma is quickly dried, vaporized, and energized through collisional excitation at high temperature. The atomic emission emanating from the plasma is viewed in either a radial or axial configuration, collected with a lens or mirror, and imaged onto the entrance slit of a wavelength selection device. Single element measurements can be performed cost‐effectively with a simple monochromator/photomultiplier tube (PMT) combination, and simultaneous multielement determinations are performed for up to 70 elements with the combination of a polychromator and an array detector. The analytical performance of such systems is competitive with most other inorganic analysis techniques, especially with regards to sample throughput and sensitivity.
Soft Modeling of Analytical Data
Authors: de Juan A. , Casassas E. , Tauler R. 
Published: September 2006

AbstractIn this contribution different methods for soft modeling data analysis are reviewed. Soft modeling approaches attempt the description of a system without the need of an a priori model postulation, physical and/or chemical. The goal of these methods is the explanation of data variance using the minimal or softer assumptions about data. Most of these soft modeling approaches are based on factor analysis (FA) decompositions of experimental data matrices. These decompositions are done by pure mathematical means and allow the identification of the number of data variance sources, their qualitative and, eventually, quantitative estimation. Results of soft modeling data analysis are useful to validate hard modeling results and also for investigation of complex chemical systems. In this contribution, the soft modeling data analysis methods described can be applied to one data matrix or to several data matrices (three‐way data sets). The purpose of these methods are mainly exploratory analysis and resolution of mixture data sets. Within the lattergroup, special attention is devoted to multivariate curve resolution (MCR) techniques and their extension to three‐way data analysis. Three examples of application are given covering the chromatographic coelution of mixtures of pesticides using liquid chromatography/diode‐array detection (LC/DAD), the infrared (IR) spectral data analysis from multiple runs of an industrial process and the interpretation of thermodynamic and conformational transitions of polynucleotides using spectrometric titrations.
Microbalance, Electrochemical Quartz Crystal
Authors: Ward Michael D. 
Published: September 2006

Abstract
The need for direct measurement of interfacial events at solid surfaces under ambient conditions has provoked surface scientists and electrochemists to develop direct in situ methods. Such processes include electroless or electrochemical metal deposition, insertion of ions into polymer ion‐exchange films, growth of oxide films on metals, or the loss of material from corrosion processes. An increasing interest in molecular films has prompted development of methods for measuring adsorption of molecules from vapor or liquid phases. Many of these processes share a common feature, namely they are accompanied by changes in mass at the solid surface.

During the 1990s a new analytical method for the in situ examination of interfacial electrode processes, the electrochemical quartz crystal microbalance (EQCM), has emerged that has substantially influenced electrochemical science. This method relies on a single crystal of quartz that has been cut into a thin wafer and coated with gold electrodes on both sides. These electrodes are used to provide an alternating electric field so that the crystal is vibrated at a specific resonant frequency, while one of the electrodes is simultaneously used as a working electrode in an electrochemical cell. The resonant frequency shifts upon changes in mass that occur on the working electrode during an electrochemical process, with sensitivity as high as 100 pg cm
−2
of electrode area. Recent developments also have illustrated that the quartz crystal microbalance (QCM) is capable of measuring the viscosity and density of liquids near the QCM surface. The purpose of this article is to provide the reader with a fundamental understanding of the EQCM and several illustrative examples of applications that demonstrate its unique capabilities, as well as the technical details required to build this apparatus.
Neurotransmitters, Electrochemical Detection of
Authors: Colliver Thomas L. , Ewing Andrew G. 
Published: September 2006

Abstract
In this article, various electrochemical methods used in neuronal cell studies are examined. Electrochemical methods useful for investigating neuronal communication directly in the brain and in ex vivo brain slices are discussed. Additionally, we describe how voltammetric methods can be used to make intracellular and extracellular measurements at single cells. Technical aspects of each method are emphasized and selected applications are highlighted.
Although techniques such as electron microscopy and patch clamp can be used to visualize and monitor cellular events, electrochemical methods can provide chemical information about neurotransmitters being released and transported in brain tissue or even at single cells. The main competing technique for in vivo measurements of neurotransmitters is microdialysis. Although microdialysis coupled to separation techniques can be more selective and more sensitive than electrochemical methods, the latter methods are considerably faster and more accurate in determining the in vivo concentration. At single cells, electrochemistry provides extremely small probes compared to microdialysis thus facilitating measurements of single‐cell events. Here, again, the response time associated with electrochemical methods is important for measurements of millisecond exocytosis events.
Electrochemical methods are clearly a powerful means to measure rapid changes in neurotransmitters that are electroactive and found in tissue or cellular microenvironments.
Ultraviolet/Visible Spectroelectrochemistry
Authors: Scherson Daniel A. , Tolmachev Yuriy V. , Stefan Ionel C. 
Published: September 2006

Abstract
This article reviews the field of solution‐phase ultraviolet/visible (UV/VIS) absorption spectroelectrochemistry and its application to problems in thermodynamics, kinetics, and mass transport, with emphasis on both experimental and theoretical aspects. Examples are provided for transmission in thin layer and semi‐infinite media, using optically transparent electrodes, and external and internal reflection in quiescent media. Also illustrated is the coupling of UV/VIS spectroscopy to systems under forced convection, such as rotating disk and channel electrodes, under steady state and transient conditions. Attention is also focused on spatially resolved spectroelectrochemistry for the imaging of diffusion and reaction layers. The last section is devoted to the more complex and particularly powerful modulation techniques involving diffraction, refraction and absorption in stagnant media and in the presence of convective flow. Factors that limit the sensitivity and spatial and temporal resolution of UV/VIS absorption spectroelectrochemistry, as well as its future prospects in analytical chemistry are briefly discussed.
Ultrafast Electrochemical Techniques
Authors: Forster Robert J. 
Published: September 2006

Abstract
Ultrafast electrochemical techniques provide information about the kinetics and thermodynamics of redox processes that occur at submillisecond or even nanosecond timescales. This short timescale is achieved either by making very rapid transient measurements or by using ultrasmall probes to achieve very high rates of diffusion under steady‐state conditions. Microelectrodes (i.e. electrodes with critical dimensions in the micrometer range) play pivotal roles in both approaches. Electrochemistry has several advantages over spectroscopy in that it provides direct information about electron transfer (E) and coupled chemical (C) reactions. Ultrafast electrochemical techniques now allow it to do so at times as short as 10 ns. In transient measurements, decreasing the lower accessible timescale depends critically on fabricating ultramicroelectrodes that continue to respond ideally as their critical dimension (e.g. the radius of a microdisc) decreases. It is now possible to assemble microelectrodes that respond to changes in applied potential within less than a few nanoseconds. In steady‐state approaches, ultrasmall probes are required to make short timescale measurements and various approaches that yield nanodes (i.e. electrodes of nanometer dimension) have been proposed. However, beyond the need for smaller probes and faster instrumentation, the continued development of new theory describing electron transfer is essential, where the dimensions of the zone that is depleted of reactant because of a Faradaic reaction and the electrochemical double layer become comparable.