bluuebunny/crossref_metadata_2025_split huggingface dataset:
Magnetic Resonance Imaging, Functional
Authors: Richter Wolfgang 
Published: September 2006

AbstractFunctional magnetic resonance imaging (FMRI) is an analytical method for measuring brain activity while it occurs. FMRI was first demonstrated in 1992, but it has since become the most popular neuroimaging method. Its temporal resolution is of the order of seconds and hence superior to positron emission tomography (PET). Its spatial resolution is on the order of millimeters which makes it superior to both PET and electrophysiological methods such as electroencephalography (EEG). Furthermore, FMRI is noninvasive in the sense that no external contrast agent has to be used. FMRI contrast is based on the intrinisic blood oxygenation changes that occur at the site of brain activity in response to a specific task. The exact mechanism that links activity and signal change is currently not well understood and is an area of active research.FMRI is subject to many experimental difficulties, however. A vexing problem is that of physiological (heartbeat and breathing) and gross motion. Gross motion is often coupled to the presentation of the stimulus and hence especially prone to producing artefactual activation. The analysis of the experimental data is not a standard procedure at present. While past research has generally used paradigmatic methods of analysis (hypothesis testing), nonparadigmatic (data driven) methods like fuzzy clustering analysis (FCA) or independent component analysis (ICA) have become important tools.A more complete understanding of the physiological mechanisms leading to the activation signal, and a better grasp of the proper statistical treatment of the data, are likely to increase the power of FMRI even further.
Multinuclear Magnetic Resonance Spectroscopic Imaging
Authors: Richards Todd L. 
Published: September 2006

AbstractMagnetic resonance spectroscopic imaging (MRSI) is a technique for producing spatially resolved maps or images of different chemicals that are found in the body or tissue. These chemicals may be naturally inherent or may be introduced by injection, but they must be detectable by the magnetic resonance (MR) process (i.e. they must have nuclei that have a magnetic moment, and are mobile enough to give a free‐induction decay (FID)). The MRSI technique is based on many of the same principles that are used for conventional magnetic resonance imaging (MRI) and also uses much of the same equipment as MRI. This chapter focuses on multinuclear applications of MRSI such as phosphorus‐31, carbon‐13, fluorine‐19, sodium‐23, xenon‐129, helium‐3, and boron‐11. The MRSI method is an important technique for noninvasive measurement of biochemical and physiological changes in health and disease.
Optical Coherence Tomography
Authors: Fercher A.F. 
Published: September 2006

Abstract

Optical coherence tomography (OCT) is a technique with which to peer inside a body noninvasively. Tissue structure defined by tissue absorption and scattering coefficients, and the speed of blood flow, are derived from the characteristics of light remitted by the body. Singly backscattered light detected by partial coherence interferometry (PCI) is used to synthesize the tomographic image coded in false colors. A prerequisite of this technique is a low time‐coherent but high space‐coherent light source, usually a superluminescent diode or a multimode semiconductor laser. This limits the wavelengths to the red and near‐infrared (NIR) region from about 600 nm to 1300 nm, the so‐called therapeutic window, where absorption (μ

a

≈ 0.01 mm
−1
) is small enough. Transverse resolution in OCT is diffraction limited, as in conventional imaging; depth resolution is limited by the coherence length of the light. Both figures are of the order of micrometers. Velocity resolution is of the order of 0.1 mm s
−1
. A few instruments are commercially available. At present, OCT is mainly used in the medical field, in particular in ophthalmology. Owing to the high transmissivity of ocular media, the depth penetration is considerable. Corresponding applications in dermatology are somewhat hindered by the strong scattering of epidermic tissue (μ

s

≈ 10
2
mm
−1
). As OCT provides images with a resolution comparable to conventional histology, but in real time, it can be used as a biopsy technique in a wide range of biological systems to detect diseases. These include the tomographic imaging of the internal microstructure of in vitro atherosclerotic plaques, the tomographic real‐time diagnostics for intraoperative monitoring, and in microsurgical intervention. Optical biopsy based on OCT also provides diagnostic information by differentiating the architectural morphology of urological tissue, gastrointestinal tissue, and respiratory tissue.
Photodynamic Therapy
Authors: Röder Beate 
Published: September 2006

AbstractPhotodynamic therapy (PDT) is an effective treatment of different types of cancer, virus infections, skin diseases and others using photosensitizers (PSs) which are nontoxic in the dark but become phototoxic following activation by low energy light. The PS is applied topically or systemically and should be selectively accumulated in the target tissue. The molecular mechanism of the therapy is the photodynamic effect: following light absorption energy is transferred from the PS to molecular oxygen generating singlet molecular oxygen (1O2) which causes direct or indirect photodamage of the target tissue.In clinical therapy with first generation PSs like Photofrin®typically fluences of around 100 J cm−2of red light are used. The light doses vary in dependence on the treated disease. Using PSs of second generation with very strong absorption in the red region like the very efficient m‐tetrahydroxyphenylchlorin (m‐THPC), smaller fluences, typically around 10 J cm−2, are required. According to the different optical properties and the efficiency of selective accumulation of PS in the target tissue, the drug doses vary from 1–5 mg (first generation PS) to 0.1 mg (second generation PS) per kilogram body weight.PDT is a very efficient method for the treatment of minor diseases, blood cancer, inoperable diseases like some types of bladder, brain or lung cancer, and breast carcinoma metastases. The side effects are less than in the case of chemo‐ or radiotherapy. The most common side effect is skin photosensitization. The strength of this effect depends on the PS used and also on the patients' skin type. Most of the new second generation PSs cause no or only weak skin phototoxicity. The therapeutic radius is limited by the penetration depth of the used light (in the order of some millimeters to centimeters). The method will not be very successful for the treatment of large solid tumors.
Two‐Dimensional Vibrational Correlation Spectroscopy in Biomedical Sciences
Authors: Ozaki Yukihiro , Noda Isao 
Published: September 2006

Abstract
Two‐dimensional (2‐D) vibrational correlation spectroscopy offers a new opportunity for analyzing vibrational spectra. In the 2‐D approach, spectral peaks are spread over the second dimension, thereby simplifying the visualization of complex spectra consisting of many overlapped bands, and enhancing spectral resolution. Correlation peaks appearing in the synchronous and asynchronous maps represent in‐phase and out‐of‐phase variation tendencies of corresponding band intensities, respectively. 2‐D correlation spectroscopy is very useful in unraveling infrared (IR), near‐infrared (NIR), and Raman spectra of biological molecules and biomedical materials. For example, it has a powerful deconvolution ability for highly overlapped amide I, amide II, and amide III bands of proteins, enabling these bands to be assigned to various secondary structures. 2‐D NIR correlation spectroscopy provides new insights into the hydration of proteins, and can also be used to investigate the order of perturbation‐dependent structural changes.
Fluorescence‐Based Biosensors
Authors: Brennan John D. 
Published: September 2006

Abstract

Biosensors, as defined by Biosensors and Bioelectronics, are analytical devices “incorporating a biological material, a biologically derived material or biomimetic intimately associated with or integrated within a physicochemical transducer or transducing microsystem”. Fluorescence‐based biosensors are those devices that derive an analytical signal from the fluorescence emission process. Such biosensors may be used for a wide variety of tasks, including: detection of compounds of biomedical,
1
environmental
2
or defense interest,
3
on‐line monitoring for process control,
4
monitoring of foodstuffs,
5
selective detection of compounds undergoing a chemical separation,
6
and screening of drug compounds.
7
Advantages of such devices include:
8
high selectivity; rapid response times; reusability; amenability to remote analysis; and immunity from electrical interferences. The selective nature of the complexation between the biomolecule and the analyte, combined with the small size of the device and the advantages of total internal reflection (TIR)‐based spectroscopy,
9
also results in an ability to measure analytes in complex matrixes. Such samples may include highly scattering systems such as milk or whole blood,
10
or relatively inaccessible locations such as groundwater wells, or even intracellular environments.
11

The key limitation of such devices mainly centers around the poor stability of biological compounds, which can lead to a substantial drift in instrument response over time. There is also the potential for interferences related to biological autofluorescence, and the analyte‐dependent sensitivity and limit of detection (LOD) for sensors, which rely on the nature of both the protein and the fluorescent probe utilized. Finally, in cases where immunological reagents are used, the devices can show a lack of reversibility, and may operate only as a “one‐shot” screen, without the potential for continuous, quantitative analysis.
Infrared Spectroscopy of Biological Applications
Authors: Stuart B.H. 
Published: September 2006

Abstract

Infrared (IR) spectroscopy has proved to be a powerful tool for studying biological molecules and the application of this technique to biological problems is continually expanding, particularly with the advent of Fourier transform infrared (FTIR) spectroscopy in recent decades. One of the great advantages of IR spectroscopy is that virtually any sample in virtually any state can be studied. Liquids, solutions, pastes, powders, films, fibers, gases and surfaces can all be examined with a judicious choice of sampling technique. Biological systems such as proteins, peptides, lipids, biomembranes, carbohydrates, pharmaceuticals, foods and both plant and animal tissues have all been successfully characterized using IR spectroscopy.
1–4

IR spectrometers have been commercially available since the 1940s. At that time the instruments relied on prisms to act as dispersive elements, but by the mid 1950s, diffraction gratings had been introduced into dispersive machines. The most significant advances in IR spectroscopy, however, have come about with the introduction of Fourier transform spectrometers. This type of instrument employs an interferometer and exploits the well established mathematical process of Fourier transformation. FTIR spectroscopy has dramatically improved the quality of IR spectra and minimized the time required to obtain data. Also, with improvements to computers in recent years, IR spectroscopy has made great strides.
Nuclear Magnetic Resonance of Biomolecules
Authors: Evans Jeremy N.S. 
Published: September 2006

AbstractNuclear magnetic resonance (NMR) spectroscopy exploits a property of the nucleus known as nuclear spin, which exhibits angular momentum and as such generates a local magnetic field that can be influenced by a larger static external field. In the presence of a large external magnet, the nuclear spins align with the field, with a slight excess opposed to the field. That small excess can be flipped to alignment with the field in the presence of a radiofrequency (RF) pulse of appropriate frequency. Relaxation of those spins back to the ground state results in emission of RF radiation whose frequency is an indication of the local electron density of the molecule in which the spin resides. Such information can ultimately be directly related to molecular structure. NMR spectroscopy is unique in that it can be used to image the whole human body at one extreme, and determine the three‐dimensional (3D) structure of a biomolecule within the body at the other extreme. The principal advantages of NMR are that: (i) the complete molecular structure can be determined; (ii) the technique spans all principal states of matter (solid, liquid, gas); (iii) the method is nondestructive and can be used noninvasively, as in a clinical setting. The principal disadvantages of NMR are that: (i) the technique is very insensitive (typically samples below 50 µM are difficult to study, although recent advances in nanoprobe and cryprobe technology are rapidly revising these numbers); (ii) in liquids there are molecular weight limits of around 50 kDa – although there are new methods being developed that may have a significant impact on this; (iii) in solids only limited structural information can be obtained to date.
Disaccharide, Oligosaccharide and Polysaccharide Analysis
Authors: Blackwood Anne D. , Chaplin Martin F. 
Published: September 2006

AbstractDisaccharides, oligosaccharides and polysaccharides form a very diverse and complex family of biologically important macromolecules. In order to discover their structure it is necessary to determine not only monosaccharides present and their linkage positions and sequence, but also the anomeric configuration of linkages, the ring size (furanose or pyranose), the absolute configuration (DorL) and identify any other substituents present. There is no one method that can be used to determine their fine structure; instead we must use a combination of analytical methods to gain as much information as we can. For analysis of disaccharide and oligosaccharide mixtures, separation and quantification techniques such as colorimetric and enzymatic assays, thin‐layer chromatography (TLC) or high‐performance anion‐exchange chromatography may be applied. For polysaccharide analysis separation and extraction techniques, component analysis, methylation analysis, glycosidic hydrolysis, mass spectrometry (MS) methods, and nuclear magnetic resonance (NMR) spectroscopy are required to determine the fine structure and size exclusion chromatography (SEC) coupled with light scattering (LS) detectors to determine the molecular size distribution.
Verification of Chemicals Related to the Chemical Weapons Convention
Authors: Mesilaakso Markku , Rautio Marjatta 
Published: September 2006

Abstract
This article gives a short historical review of the Chemical Weapons Convention (CWC), discusses the tasks of the Organisation for the Prohibition of Chemical Weapons (OPCW) related to chemical analysis, and lists the chemicals scheduled in the CWC. The Recommended Operating Procedures (ROPs) proposed originally by Finland and, subsequently, developed further in international cooperation, as well as the Standard Operating Procedures (SOPs) of the OPCW are briefly discussed. Strategy for analysis of CWC‐related chemicals in an off‐site laboratory is presented. The international interlaboratory comparison (round‐robin) and proficiency tests are discussed.
Detection and Screening of Chemicals Related to the Chemical Weapons Convention
Authors: Nieuwenhuizen Maarten S. 
Published: September 2006

AbstractThe Organization for the Prohibition of Chemical Weapons (OPCW), which was established to achieve the object and purpose of the Chemical Weapons Convention (CWC), conducts verification activities and as a result numerous inspections take place. Detection plays a major role during many of the possible inspection scenarios and is a most important component of the health and safety policy of the Organization. This article deals with detection equipment for vapors, liquids, contaminated solids and industrial chemicals as well as explosive or flammable vapor mixtures or lack of oxygen.
Fourier Transform Infrared in On‐Site and Off‐Site Analysis of Chemicals Related to the Chemical Weapons Convention
Authors: Söderström Martin T. 
Published: September 2006

Abstract
Fourier transform infrared spectroscopy (FTIR) is an analytical technique, which gives characteristic spectra. The spectra can be used like fingerprints in the identification of chemicals. The chemicals can be identified by comparison with reference data or, in some cases, by interpretation, which can be followed by synthesis for confirmation.
When FTIR is connected to a gas chromatograph (GC) and the results are used together with those from mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy, very complex environmental samples containing unknown chemicals can be analyzed reliably.
Gas Chromatography/Mass Spectrometry in On‐Site Analysis of Chemicals Related to the Chemical Weapons Convention
Authors: Häkkinen Vesa M.A. 
Published: September 2006

Abstract
This article describes the current procedures for on‐site gas chromatographic/mass spectrometric analysis of samples collected during inspections related to the Chemical Weapons Convention (CWC). Such inspections are made by an inspection team compiled by the Organization for the Prohibition of Chemical Weapons (OPCW). The analytical procedures are described in a standard operating procedure covering gas chromatographic analysis, mass spectrometric analysis, data analysis, and quality control. The approved analytical instrumentation for on‐site inspections is also described.
Liquid Chromatography/Mass Spectrometry in Analysis of Chemicals Related to the Chemical Weapons Convention
Authors: Black Robin M. , Read Robert W. 
Published: September 2006

AbstractLiquid chromatography/mass spectrometry (LC/MS) is the direct coupling of a chromatographic separation of analytes dissolved in a liquid phase with mass spectrometric detection/identification. Analytes are separated by one or more mechanisms, usually involving hydrophobic, polar or ionic interactions. The components eluting from the LC are introduced directly into the mass spectrometer via an interface, which removes the solvent and ionizes the analyte molecules to produce positive or negative ions. These ions are separated by the mass spectrometer on the basis of their mass‐to‐charge (m/z) ratios. The recent introduction of versatile and robust interfaces, which use atmospheric pressure ionization (API) (atmospheric pressure chemical ionization (APCI) and electrospray (ES) ionization), has lead to increasing application of LC/MS to the analysis of chemical warfare (CW)‐related analytes.Although LC/MS can be used for the direct analysis of CW agents in aqueous samples, its major application in this field is for the analysis of hydrolysis products of CW agents and other polar degradation products. Reversed phase LC/MS provides a rapid screening procedure for hydrolysis products such as phosphonic acids and thiodiglycol, avoiding the tedious isolation and derivatization required for gas chromatography/mass spectrometry (GC/MS). Increased structural information for unequivocal identification, or improved limits of detection in trace analysis, can be obtained using liquid chromatography/tandem mass spectrometry (LC/MS/MS). LC/MS/MS is also useful for detecting biological markers of poisoning by CW agents in cases where GC/MS is unsuitable.
Automation in the Clinical Laboratory
Authors: McPherson Richard A. 
Published: September 2006

Abstract
Total laboratory automation (TLA) is an approach to laboratory instrumentation that replaces human operators with robotic devices for the performance of highly repetitive tasks in the preparation and transport of specimens. TLA will consolidate the control and oversight for multiple different analytical instruments to a smaller number of operators, thus reducing the costs of labor in laboratory testing. Benefits of TLA include reduction of human errors in specimen handling and improvements in overall process control, including faster turn‐around‐times (TAT) from specimen collection to test result reporting. Possible detriments include very high costs for equipment installation and disruption of workforces trained in existing technologies. Most clinical laboratories will soon face a decision about implementing TLA (or portions of it) to reduce operating costs in order to offset falling reimbursements for medical services.
Biosensor Design and Fabrication
Authors: Urban G.A. 
Published: September 2006

AbstractThis paper presents the use of biosensor devices for bioanalytical purposes. In contrast to common analytical tools using sophisticated and bulky devices, biosensors should be able to perform measurements in untreated samples in a simple and inexpensive manner. As a model creating biosensors serves nature which produces a variety of selective molecules during evolution that can be used in technical sensor devices. Combining such natural molecules with methods from microelectronics, mass fabrication of laboratories on chip seems feasible. Emerging markets for such tools can be seen in medicine, drug screening and biotechnology.After explaining the principles of biosensors different transducing methods are explained showing advantages and disadvantages for creating biosensors. The greatest emphasis is laid on electrochemical and optical principles which exhibit an overwhelming experience and the largest impact on future developments. Despite such developments, acoustic and calorimetric transducers are also explained. As biological sensing agents enzymes, antibodies and DNA are described with appropriate immobilizing procedures.Additionally, new aspects for creating a laboratory‐on‐chip using microanalytical systems (μTAS) including microfluidics and actuator modules are given for creating sensing systems for metabolic parameters and also cell‐based and affinity‐based systems for screening purposes. The purpose of this section is to give an overview and to explain the present possibilities for creating biosensor systems and ends up with an outlook in the near analytical future for new sophisticated and miniaturized analytical systems.
Capillary Electrophoresis in Clinical Chemistry
Authors: Xu Yan 
Published: September 2006

AbstractCapillary electrophoresis (CE) is electrophoresis in capillary format. It is the most efficient and versatile separation technique nowadays for analysis of small and large molecules. Clinical chemistry is a science that applies the knowledge of chemistry to the understanding of the human in health and disease. Implementation of CE technique in clinical laboratories will enhance the capability of the current clinical diagnostic system, and improve the quality of clinical testing. Owing to the nature of clinical diagnostics, the adoption of CE methods in clinical laboratories has been slow. However, CE has begun to replace some older and antiquated methods in some pioneering clinical laboratories.This review includes a brief introduction to the CE technique (i.e. the separation principle, modes of operation, instrumentation, and practical considerations), and a summary of CE's applications in clinical chemistry (i.e. protein analysis, drug monitoring, DNA and RNA analyses, diagnosis of metabolic disorders, and single‐cell analysis), as well as the future prospects for the CE technique.