bluuebunny/crossref_metadata_2025 huggingface dataset:
Microglial inflammation in the parkinsonian substantia nigra: relationship to alpha-synuclein deposition
Authors: Croisier Emilie , Moran Linda B , Dexter David T , Pearce Ronald KB , Graeber Manuel B
Published: June 2005

Background

The role of both microglial activation and alpha-synuclein deposition in Parkinson's disease remain unclear. We have tested the hypothesis that if microglia play a primary role in Parkinson's disease pathogenesis, the microglial "activated" phenotype should be associated with histopathological and/or clinical features of the disease.

Methods

We have examined microglial MHC class II expression, a widely used marker of microglial activation, the occurrence of CD68-positive phagocytes and alpha-synuclein immunoreactivity in post-mortem human substantia nigra affected by idiopathic Parkinson's disease (PD). Using semi-quantitative severity ratings, we have examined the relationship between microglial activation, alpha-synuclein deposition, classical neuropathological criteria for PD, subtype of the disease and clinical course.

Results

While we did not observe an association between microglial MHC class II expression and clinical parameters, we did find a correlation between disease duration and the macrophage marker CD68 which is expressed by phagocytic microglia. In addition, we observed a significant correlation between the degree of MHC class II expression and alpha-synuclein deposition in the substantia nigra in PD.

Conclusion

While microglia appeared to respond to alpha-synuclein deposition, MHC class II antigen expression by microglia in the substantia nigra cannot be used as an indicator of clinical PD severity or disease progression. In addition, a contributory or even causative role for microglia in the neuronal loss associated with PD as suggested by some authors seems unlikely. Our data further suggest that an assessment of microglial activation in the aged brain on the basis of immunohistochemistry for MHC class II antigens alone should be done with caution.
Identification of co-regulated transcripts affecting male body size in Drosophila
Authors: Coffman Cynthia J , Wayne Marta L , Nuzhdin Sergey V , Higgins Laura A , McIntyre Lauren M
Published: June 2005

Factor analysis is an analytic approach that describes the covariation among a set of genes through the estimation of 'factors', which may be, for example, transcription factors, microRNAs (miRNAs), and so on, by which the genes are co-regulated. Factor analysis gives a direct mechanism by which to relate gene networks to complex traits. Using simulated data, we found that factor analysis clearly identifies the number and structure of factors and outperforms hierarchical cluster analysis. Noise genes, genes that are not correlated with any factor, can be distinguished even when factor structure is complex. Applied to body size in Drosophila simulans, an evolutionarily important complex trait, a factor was directly associated with body size.
Modulation of Calmodulin Gene Expression as a Novel Mechanism for Growth Hormone Feedback Control by Insulin-like Growth Factor in Grass Carp Pituitary Cells
Authors: Huo Longfei , Fu Guodong , Wang Xinyan , Ko Wendy K. W. , Wong Anderson O. L.
Published: June 2005

Calmodulin (CaM), the Ca2+ sensor in living cells, is essential for biological functions mediated by Ca2+-dependent mechanisms. However, modulation of CaM gene expression at the pituitary level as a means to regulate pituitary hormone synthesis has not been characterized. In this study we examined the functional role of CaM in the feedback control of GH by IGF using grass carp pituitary cells as a cell model. To establish the structural identity of CaM expressed in the grass carp, a CaM cDNA, CaM-L, was isolated from the carp pituitary using 3′/5′ rapid amplification of cDNA ends. The open reading frame of this cDNA encodes a 149-amino acid protein sharing the same primary structure with CaMs reported in mammals, birds, and amphibians. This CaM cDNA is phylogenetically related to the CaM I gene family, and its transcripts are ubiquitously expressed in the grass carp. In carp pituitary cells, IGF-I and IGF-II induced CaM mRNA expression with a concurrent drop in GH transcript levels. These stimulatory effects on CaM mRNA levels were not mimicked by insulin and appeared to be a direct consequence of IGF activation of CaM gene transcription without altering CaM transcript stability. CaM antagonism and inactivation of calcineurin blocked the inhibitory effects of IGF-I and IGF-II on GH gene expression, and CaM overexpression also suppressed the 5′ promoter activity of the grass carp GH gene. These results, as a whole, provide evidence for the first time that IGF feedback on GH gene expression is mediated by activation of CaM gene expression at the pituitary level.
Prokineticins (Endocrine Gland-Derived Vascular Endothelial Growth Factor and BV8) in the Bovine Ovary: Expression and Role as Mitogens and Survival Factors for Corpus Luteum-Derived Endothelial Cells
Authors: Kisliouk Tatiana , Podlovni Helena , Spanel-Borowski Katharina , Ovadia Oded , Zhou Qun-Yong , Meidan Rina
Published: June 2005

A highly vascular endocrine gland, the corpus luteum (CL) is an excellent model for the study of angiogenic factors. Prokineticins (PK-1 and -2), also termed endocrine-gland-derived vascular endothelial growth factor (VEGF) and BV8 are newly identified proteins described as selective angiogenic mitogens. We previously identified PK binding sites, two closely homologous G protein-coupled receptors (PK-R1 and PK-R2) in human and bovine ovarian cells, but their function remained unknown. In this study we examined the presence and effects of PK in CL-derived endothelial and steroidogenic cell types (LEC and LSC, respectively). PK-1 mRNA was identified in CL and follicles by real-time PCR, using primers specific for the bovine PK-1 sequence (retrieved from Bos taurus whole genome shotgun database). PK were potent angiogenic mitogens for LEC; they enhanced cell proliferation, elevated [3H]thymidine incorporation, MAPK activation, and c-jun/fos mRNA expression. The effects of PK proteins on cell survival were examined by nuclear morphology (4′,6-diamidino-2-phenylindole dihydrochloride staining), measurement of DNA fragmentation (terminal dUTP nucleotide end labeling assay), and caspase-3 cleavage. Results obtained by these techniques demonstrated that PK protected LEC from serum starvation-induced apoptosis. Stress conditions such as serum withdrawal, TNF-α, and hypoxia markedly increased PK-R2 expression, whereas mRNA levels of PK-R1 remained unchanged. These suggest that the antiapoptotic effect of PK-1 on LEC may be mediated via PK-R2. PK-1 increased VEGF mRNA expression by LSC, implying that it could also indirectly, via VEGF, affect luteal angiogenesis. Together, these findings suggest an important role for PK-1 in luteal function by acting as a mitogen and survival factor in LEC.
Short-Term Stimulation of Lipogenesis by 3,5-l-Diiodothyronine in Cultured Rat Hepatocytes
Authors: Giudetti Anna M. , Leo Monica , Geelen Math J. H. , Gnoni Gabriele V.
Published: June 2005

Short-term effects of 3,5-l-diiodothyronine (T2) on lipid biosynthesis were studied in cultured hepatocytes from hypothyroid rats. A comparison with the effects of T3 was routinely carried out. After T2 addition to cell cultures, a distinct stimulation of fatty acid and cholesterol syntheses, measured as incorporation of [1-14C]acetate into these lipid fractions, was observed. The T2 dose-dependent effect on both metabolic pathways, already detectable at 10−8-10−9m, reached a 2-fold stimulation at 10−5m T2. At this concentration, the stimulatory effect was evident within 1 h of T2 addition to the hepatocytes and increased with time up to the length of the experimental period of 4 h. T2 stimulation of lipogenesis was also confirmed by incubating hepatocytes with [3H]H2O, used as an independent index of lipogenic activity. The effects of T2 are rather specific as 3,3′,5,5′-tetraiodo-d-thyronine and 3,5-diiodo-l-tyrosine were practically ineffective on both fatty acid and cholesterol synthesis. Analysis of various lipid fractions showed that T2 addition to the cells produced a significant stimulation of the incorporation of newly synthesized fatty acids into both neutral and polar lipids. By comparing the effects induced by T2 with those seen in the presence of T3, it appeared that T2 was able to mimic T3 effects. Experiments conducted in the presence of cycloheximide, a protein synthesis inhibitor, indicated that the T2 stimulatory effect on fatty acid and cholesterol synthesis was essentially independent of protein synthesis.
The simultaneous loss ofArxandPax4genes promotes a somatostatin-producing cell fate specification at the expense of the α-and β-cell lineages in the mouse endocrine pancreas
Authors: Collombat Patrick , Hecksher-Sørensen Jacob , Broccoli Vania , Krull Jens , Ponte Ilaria , Mundiger Tabea , Smith Julian , Gruss Peter , Serup Palle , Mansouri Ahmed
Published: June 2005

The specification of the different mouse pancreatic endocrine subtypes is determined by the concerted activities of transcription factors. However, the molecular mechanisms regulating endocrine fate allocation remain unclear. In the present study, we uncover the molecular consequences of the simultaneous depletion of Arx and Pax4 activity during pancreas development. Our findings reveal a so far unrecognized essential role of the paired-box-encoding Pax4 gene. Specifically, in the combined absence of Arx and Pax4, an early-onset loss of mature α- and β-cells occurs in the endocrine pancreas, concomitantly with a virtually exclusive generation of somatostatin-producing cells. Furthermore, despite normal development of the PP-cells in the double-mutant embryos, an atypical expression of the pancreatic polypeptide (PP) hormone was observed in somatostatin-labelled cells after birth. Additional characterizations indicate that such an expression of PP was related to the onset of feeding, thereby unravelling an epigenetic control. Finally, our data provide evidence that both Arx and Pax4 act as transcriptional repressors that control the expression level of one another, thereby mediating proper endocrine fate allocation.
Muscle arm development inCaenorhabditis elegans
Authors: Dixon Scott J. , Roy Peter J.
Published: June 2005

In several types of animals, muscle cells use membrane extensions to contact motor axons during development. To better understand the process of membrane extension in muscle cells, we investigated the development of Caenorhabditis elegans muscle arms, which extend to motor axons and form the postsynaptic element of the neuromuscular junction. We found that muscle arm development is a highly regulated process: the number of muscle arms extended by each muscle, the shape of the muscle arms and the path taken by the muscle arms to reach the motor axons are largely stereotypical. We also investigated the role of several cytoskeletal components and regulators during arm development, and found that tropomyosin (LEV-11), the actin depolymerizing activity of ADF/cofilin (UNC-60B) and, surprisingly, myosin heavy chain B(UNC-54) are each required for muscle arm extension. This is the first evidence that UNC-54, which is found in thick filaments of sarcomeres, can also play a role in membrane extension. The muscle arm phenotypes produced when these genes are mutated support a `two-phase' model that distinguishes passive muscle arm development in embryogenesis from active muscle arm extension during larval development.
Hox-controlled reorganisation of intrasegmental patterning cues underliesDrosophilaposterior spiracle organogenesis
Authors: Merabet Samir , Hombria James Castelli-Gair , Hu Nan , Pradel Jacques , Graba Yacine
Published: June 2005

Hox proteins provide axial positional information and control segment morphology in development and evolution. Yet how they specify morphological traits that confer segment identity and how axial positional information interferes with intrasegmental patterning cues during organogenesis remain poorly understood. We have investigated the control of Drosophilaposterior spiracle morphogenesis, a segment-specific structure that forms under Abdominal-B (AbdB) Hox control in the eighth abdominal segment (A8). We show that the Hedgehog (Hh), Wingless (Wg) and Epidermal Growth Factor Receptor (Egfr) pathways provide specific inputs for posterior spiracle morphogenesis and act in a genetic network made of multiple and rapidly evolving Hox/signalling interplays. A major function of AbdB during posterior spiracle organogenesis is to reset A8 intrasegmental patterning cues, first by reshaping wg and rhomboid expression patterns, then by reallocating the Hh signal and later by initiating de novo expression of the posterior compartment gene engrailed in anterior compartment cells. These changes in expression patterns confer axial specificity to otherwise reiteratively used segmental patterning cues, linking intrasegmental polarity and acquisition of segment identity.
Robust control of microvibrations with experimental verification
Authors: Tan A C H , Meurers T , Veres S M , Aglietti G , Rogers E
Published: June 2005

The paper addresses the problem of actively attenuating a particular class of vibrations, known as microvibrations, which arise, for example, in panels used on satellites. A control scheme that incorporates feedback action is developed which operates at a set of dominant frequencies in a disturbance spectrum, where the control path model is estimated online. Relative to earlier published techniques, a new feature of the presented controller is the use of the inverse Hessian to improve adaptation speed. The control scheme also incorporates a frequency estimation technique to determine the relevant disturbance frequencies with higher precision than the standard fast Fourier transform (FFT). The control scheme is implemented on an experimental test-bed and the total achieved attenuation, as measured from the experiments, is 26 dB. The low computational demand of the control scheme allows for single chip controller implementation, a feature which is particularly attractive for potential applications areas, such as small satellites, where there are critical overall weight restrictions to be satisfied while delivering high quality overall performance.
Investigation of tooth contact deviations from the plane of action and their effects on gear transmission error
Authors: Wink C H , Serpa A L
Published: June 2005

In this paper tooth contact deviations from the plane of action and their effects on gear transmission error are investigated. Tooth contact deviations come from intentional modification of involute tooth surfaces such as tip and root profile relief; manufacturing errors such as adjacent pitch error, profile errors, misalignment and lead errors; and tooth elastic deflections under load, for example, bending and local contact deflections. Those deviations are usually neglected on gear tooth contact models. A procedure to calculate the static transmission error of spur and helical gears under loading is proposed. In the proposed procedure, contact analysis is carried out on the whole tooth surface, eliminating the usual assumption that tooth contact occurs only on the plane of action. Lead and profile modifications, manufacturing errors and tooth elastic deflections are considered in the calculation procedure. The method of influence coefficients is employed to calculate the tooth elastic deflections. Load distribution on gear meshing is determined using an iterative-incremental method. Results of some numerical examples of spur and helical gears are analysed and discussed. The results indicate that the tooth contact deviations from the plane of action can lead to imprecision on the gear transmission error calculation if they are not take into account. Therefore, the proposed procedure provides a more accurate calculation methodology of gear transmission error, since a global contact analysis is done.
Design of hybrid machines for nonuniform motion production
Authors: Yuan Z , Gilmartin M J , Douglas S S
Published: June 2005

Linkage mechanisms driven at constant angular velocity (CV) using a motor and flywheel have traditionally been used to produce fixed nonuniform motions. This type of system offers advantages of smooth motor torques, energy conservation and fast operational speeds. By incorporating a servo motor drive with a conventional CV drive in a two degree of freedom (DOF) linkage, the resulting hybrid machine can provide programmability. In this paper, two different hybrid mechanisms are optimally designed to provide a range of output motions with minimized torque and power requirements from the servo motor. The results are compared with those for a direct servo motor drive system.
A method for testing group differences of scale validity in multiple population studies
Authors: Raykov Tenko
Published: June 2005

A method for testing equality in validity of multi‐component measuring instruments across populations is outlined. The approach is developed within the framework of covariance structure modelling and complements earlier research on examining group differences in scale reliability. The procedure is particularly useful for purposes of ascertaining comparability of validity when constructing and developing measuring instruments. The method also provides ranges of plausible values for differences in composite validity across several populations and allows one to evaluate group discrepancies in validity of behavioural scales. The approach is illustrated using data from a cognitive intervention study.
A statistical model for binocular rivalry
Authors: van der Ven Ad H. G. S. , Gremmen Frans M. , Smit Jan C.
Published: June 2005

A probabilistic model is presented for the phase durations in binocular rivalry experiments. The hypothetical construct of inhibition or reaction inhibition is used to account for the length of the successive phases of left‐eye dominance and right‐eye dominance. In accordance with Hull's Postulate X.B. it is assumed that the inhibition increases linearly at rate a1 during periods of left‐eye dominance and decreases linearly at rate a0 during periods of right‐eye dominance. Two different versions of the proposed model are presented: the beta and the Bessel inhibition models. Inhibition fluctuates between the boundaries 0 and 1 in the beta inhibition model and between −∞ and +∞ in the Bessel inhibition model. The transition rates λ1(t) for switches from a state of left‐eye dominance to a state of right‐eye dominance, and λ0(t) for switches from a state of right‐eye dominance to a state of left‐eye dominance depend on inhibition: , , where l1 is a non‐decreasing function and l0 is a non‐increasing function. In the beta inhibition model and . In the Bessel inhibition model and . Special attention is given to the derivation of the expectation of the stationary phase durations.
The mean and variance of the selection differential after top‐down selection from a mixture of normal samples
Authors: De Corte Wilfried
Published: June 2005

A procedure is presented for determining the mean and variance of the selection differential for top‐down selections in which the candidates come from populations that have a different average score on the selection measure. Although the procedure is based on the same stochastic model and requires identical data to the currently available method for estimating the mean selection differential, it has the advantage that the resulting expressions are valid for finite‐sample selection decisions and that the variance of the selection differential can also be assessed. The difference between the two procedures is illustrated by means of an example application, and it is shown how the present results are particularly helpful in determining the expected utility of personnel selection decisions.
Multilevel IRT using dichotomous and polytomous response data
Authors: Fox J. ‐P.
Published: June 2005

A structural multilevel model is presented where some of the variables cannot be observed directly but are measured using tests or questionnaires. Observed dichotomous or ordinal polytomous response data serve to measure the latent variables using an item response theory model. The latent variables can be defined at any level of the multilevel model. A Bayesian procedure Markov chain Monte Carlo (MCMC), to estimate all parameters simultaneously is presented. It is shown that certain model checks and model comparisons can be done using the MCMC output. The techniques are illustrated using a simulation study and an application involving students' achievements on a mathematics test and test results regarding management characteristics of teachers and principles.
An affine invariant rank‐based method for comparing dependent groups
Authors: Wilcox Rand R.
Published: June 2005

A basic property of various rank‐based hypothesis testing methods is that they are invariant under a linear transformation of the data. For multivariate data, a generalization of this property is sometimes sought (called affine invariance), but typically techniques for assigning ranks do not achieve this goal, or it is assumed that sampling is from a symmetric distribution. A rank‐based method is suggested for comparing dependent groups that is based on halfspace depth, is affine invariant in terms of difference scores, and allows sampling from asymmetric distributions.
Perceived Workplace Fairness, Transformational Leadership and Motivation in the Nigeria Police: Implications for Change
Authors: Adebayo Dada O.
Published: June 2005

Recent attempts at raising the work motivation of the Nigeria police by the present democratic government of Nigeria have largely been directed at the provision of material resources without adequate attention to other organisational factors that are salient to motivation. To fill this gap, the current study examined the interaction of perceived workplace fairness and transformational leadership behaviour on the work motivation of the rank and file of the Nigeria police. Using a cross-sectional survey design, data were collected from a total of 184 participants. Results of a 2 × 2 ANOVA revealed significant main effects as well as an interaction effect. Post hoc analysis showed that participants were best motivated when both perceived transformational leadership behaviour and workplace fairness were high, and least motivated when low. Social exchange theory was used to explain these findings and its implications for motivational changes for the Nigeria police are discussed.
Shopping Centre Design, Decline and Crime
Authors: Poyser Sam
Published: June 2005

It is now widely accepted that the design of buildings and their surroundings can influence the commission of crime and nuisance behaviour (Garrad, 1999) and that the proper design and effective use of the built environment can lead to a reduction in the fear and incidence of crime, and an improvement in the quality of life (Skogan, 1990a). This article reports on research undertaken to determine whether architects, designing shopping centres in the 1960s and late 1990s, were aware of the link between environmental design and criminal opportunity. It goes on to examine what relation that ignorance/awareness might have to criminal opportunity, nuisance behaviour, and fear of crime in users. The related issue of management/maintenance of centres is also examined. The design of two Portsmouth, England, shopping centres (the ‘Tricorn’—planned and built in the 1960s and ‘Gunwhaf Quays' — planned and built in the late 1990s) is compared. The research findings utilising interviews, questionnaires and examination of local newspaper reports suggest that users found the ‘Tricorn’ to be poorly designed, ill maintained, to attract crime and nuisance behaviour, and to make them feel unsafe whilst, in contrast, users felt that ‘Gunwharf Quays' is well designed and maintained. Many feel that these factors may be connected to their feelings of safety, and to what they observed as low levels of crime and nuisance behaviour.

Overall, the findings indicate that design and maintenance are important elements in relation to levels of crime, nuisance, and fear of crime in shopping centres. Several recommendations are made in the light of these findings.
Police-Media Relations at Critical Incidents: Interviews from Oklahoma City
Authors: Caeti Tory J. , Liederbach John , Bellew Steven S.
Published: June 2005

The policing of critical incident scenes, including natural disasters, hazardous materials spills, hostage situations, and terrorist attacks, has become an especially salient topic in the post-September 11 environment. Given the attention-grabbing nature of these events, police administrators are often faced with the task of building and maintaining relationships with members of the media at these scenes, primarily reporters and their crews who often pursue goals that are in direct conflict with those of law enforcement. This article examines the issues related to police—media relations at critical incident scenes using interview data from subjects involved in policing the scene of the Oklahoma City bombing and the related trials of Timothy McVeigh and Terry Nichols. These interviews provide a context for the presentation of guidelines important to police administrators who must be able to forge successful relationships with the media at critical incidents.
Organised Crime: Redefined for Social Policy
Authors: Clark Mark
Published: June 2005

This article argues that the modern concept of problem-orientated policing requires that organised crime be redefined in sociological and political science terminology to identify opportunities for community-based policing initiatives to be utilised in undermining its institutional base. It seeks to redefine organised crime by its use of power and acts of victimisation. The article reviews a number of traditional organised crime groups by undertaking an historical power analysis process to substantiate this argument. It identifies the conditions and societies that gave rise to organised crime. It discusses the initial community or institutional purpose of the organised group and how it mutated to dominate by acts of criminal victimisation.

The view is expressed that a victim-centred, problem-orientated policing policy is necessary to understand the legitimacy of organised crime in isolated communities and to remove barriers between the police and these communities. This view promotes the use of specially trained community police officers who are directly linked to other agencies engaged in suppressing organized crime to develop community capacity building to resist crime in isolated communities.
Indirect Amplitude Stabilization of a Tunable Laser through Control of the Intensity of a Pump Laser by an Electro-Optic Modulator
Authors: Tran Chieu D. , Furlan Ricardo J.
Published: June 2005

A novel method has been developed to stabilize the intensity of a tunable laser. In this method, the tunable laser is amplitude-stabilized indirectly by controlling the intensity of the pump laser through an electro-optic modulator placed between the pump and the tunable lasers. A small portion of the tunable laser beam was split into a reference photodiode to provide a reference signal for the feedback driver to drive the Pockels cell. Any fluctuation in the intensity of the tunable laser is compensated for by varying the intensity of the pump laser through the feedback driven Pockels cell. Results obtained on the Ti-sapphire laser pumped by an ion laser demonstrate that up to 100 × reduction in the laser noise level can be accomplished by use of this method. Furthermore, with this method, it is possible to adjust the intensity of the laser to be exactly equal for different wavelengths, and to maintain this level for as long as the stabilization is activated. Applications of this method for different types of tunable lasers, including dye and F-center lasers, are discussed.
Fluoride Interference in the Determination of Boron by Inductively Coupled Plasma Emission Spectroscopy
Authors: Fucskó János , Tan Samantha H. , La Hamy , Balazs Marjorie K.
Published: June 2005

Boron determination in borophosphosilicate glass films by the ICP-AES or ICP-MS technique can be performed after dissolution of the sample in HF solution. However, addition of HF to boric acid standard solution can cause a drift in the slope of the calibration curve. The signal change was correlated with the kinetics of the borontetrafluoride complex formation reaction. The mechanism was explained by the selectively increased boron transport into the plasma, which was caused by the more efficient diffusion of borontrifluoride gas through the aerosol particles into the nebulizer gas. With the kinetics of borontetrafluoride complex formation taken into consideration, an accurate and precise method was developed for the determination of boron in BPSG films.
Characterization of Rhodamine 6G-Doped Thin Sol-Gel Films
Authors: Narang Upvan , Bright Frank V. , Prasad Paras N.
Published: June 2005

Rhodamine 6G- (R6G) doped thin sol-gel films were cast on glass microscope slides and characterized with the use of steady-state and time-resolved fluorescence spectroscopy. The fluorescence intensity, photodegradation under laser illumination, and excited-state decay kinetics were all investigated as a function of dopant concentration. The excited-state decay kinetics of highly doped films show clear evidence of R6G aggregation. Photodegradation under laser illumination is very interesting and is discussed in detail.
Structural Mass Spectrometry of Matrix-Assisted Laser-Desorbed Biomolecules by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry: Photoionization and Photofragmentation
Authors: Solouki Touradj , Russell David H.
Published: June 2005

Laser desorption ionization of compounds that absorb 337 nm (e.g., vitamin B12 and selected porphyrins) are examined by using Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. The experiments are performed by mixing the sample with a host compound that promotes desorption and/or ionization. The relative abundance of photofragment ions can be controlled by simple adjustments of parameters such as the laser power and matrix-to-analyte ratio. In addition, it is shown that gas-phase photoionization/photodissociation of laser-desorbed species by a second laser pulse provides structural information for both negative and positive ions.
Stability in Aqueous Media of 316L Stainless Steel Films Deposited on Internal Reflection Elements
Authors: Pedraza A. J. , Godbole M. J. , Bremer P. J. , Avci R. , Drake B. , Geesey G. G.
Published: June 2005

Thin films of 316L stainless steel were sputter-deposited on cylindrical internal reflection elements (IREs) made of germanium. These films are intended for use in Fourier transform infrared (FT-IR) spectroscopy studies on the stability of stainless steel in aqueous media. In these deposits the films tend to peel off the substrate when immersed in water, probably due to galvanic corrosion at the metal/substrate interface. Deposition of a 2-nm-thick layer of chromium oxide on the substrate prior to the deposition of the steel was beneficial on three counts. It provided an electrically insulating layer, it enhanced adhesion, and it solved the steel/germanium incompatibility problem. It was also found that annealing the substrate prior to deposition remarkably enhances the film adhesion and improves the optical properties of the substrate. The microstructure, the topography, and the chemical composition of the films were characterized by scanning and transmission electron microscopy, Auger electron spectroscopy, and atomic force microscopy. The only significant difference between the austenitic stainless steel target material and the film is that the crystalline structure of the film is body-centered cubic. The optical properties of the system germanium/metallic film/water were studied and calculated with the help of a computer program. The absorbance of the water bands in the IR range was measured in coated Ge-IRE.
Comparison of the UV Resonance Raman Spectra of Bacteria, Bacterial Cell Walls, and Ribosomes Excited in the Deep UV
Authors: Chadha S. , Manoharan R. , Moënne-Loccoz P. , Nelson W. H. , Peticolas W. L. , Sperry J. F.
Published: June 2005

Resonance Raman spectra have been obtained with 218-nm excitation for Escherichia coli and Staphylococcus epidermidis. Large intensity differences seen in the tryptophan-associated 1556-cm−1 peak appear to be strongly related to Gram type. Unlike E. coli, S. epidermidis possess a very intense peak at 1658 cm−1 which varies in intensity with cultural conditions. Spectra excited from E. coli and Enterobacter aerogenes with 200-nm light show peaks which strongly reflect nucleic acid composition, unlike spectra excited at 218 nm. Purified, separated ribosomes of E. coli produce spectra which are dominated by nucleic acid vibrations when excited at 242 nm, but have peaks belonging nearly exclusively to protein aromatic amino acids when excited at 222 nm. The relative weakness of bacterial RNA modes excited at 222 nm from whole cells and ribosomes is attributed to nucleic acid hypochromism.
Maximum-Likelihood Restoration Data Processing Techniques Applied to Matrix-Assisted Laser Desorption Mass Spectra
Authors: Brown R. S. , Gilfrich N. L.
Published: June 2005

Maximum-likelihood restoration (MLR) data processing is applied to matrix-assisted laser desorption time-of-flight mass spectra of several peptide/protein samples. It is shown that this technique can enhance mass resolution for peptides (porcine insulin; MW = 5777.58 Da) sufficiently to assist in the identification of various matrix adduct ion species formed in the laser desorption process. For higher-molecular-weight proteins, mass resolution enhancement is such that peak overlap contributions from partially resolved matrix adduct ion species can be minimized. Mass accuracies are improved by approximately a factor of six for a sample of a bacterial protease (Subtilisin Carlsberg; Subtilopeptidase A) from Bacillus licheniformis (MW = 27,288.4 Da). The MLR technique also supports the contention that the mass resolution degradation observed with increasing analyte mass is at least partially due to ion signal tailing, presumably caused by secondary ion species being produced in the detection process. This factor is also postulated as being at least partially responsible for the lack of success at resolution enhancement for higher mass analytes (bovine serum albumin; MW = 66,430.3 Da) where the multiple matrix adduct ion species produced can no longer be resolved from the protonated molecular ion species, thus limiting experimental mass measurement accuracies.
Selective Enhanced Raman Scattering from an Oxacarbocyanine Dye and 1-Phenyl-5-Mercaptotetrazole Adsorbed to Silver and Silver Halide Surfaces in Photographic Films
Authors: Brandt E. S.
Published: June 2005

Enhanced Raman scattering (ERS) spectroscopy has been used to obtain characteristic vibrational spectra of two photographically-useful molecules adsorbed to the surface of silver-containing photographic coating (film) processing residues. Films containing gelatin dispersions of silver halide microcrystals were coated with a typical oxacarbocyanine spectral sensitizing dye and subsequently treated with a common photographic silver image modifier, 1-phenyl-5-mercaptotetrazole (HPMT). With the selection of a laser excitation frequency within the absorption band of the J-aggregate of the dye (λmax ≈ 550 nm), Raman spectra which are unique to the adsorbed dye were observed. When the laser excitation was shifted bathochromically (647.1 nm), characteristic spectra of the adsorbed silver salt of HPMT (AgPMTads), which does not normally absorb light efficiently at this wavelength, were obtained from the same coatings. This work represents the first time vibrational spectra from both chromophoric and nonchromophoric (in the visible frequency range) Raman-active molecules have been observed within a common photographic chemical environment by the use of molecular resonance enhancement in combination with surface-enhanced Raman scattering (SERS).
Luminescence Study of UO2+2 Binding to Immobilized Datura Innoxia Biomaterial
Authors: Ke Huei-Yang D. , Rayson Gary D.
Published: June 2005

The spectrally and temporally resolved UO2+2 fluorescence signals have been measured for solid samples of UO2+2 -Datura, UO2+2-(immobilized Datura), and UO2+2-(silicate polymer) at liquid nitrogen temperature. The binding capacity of UO2+2 to Datura innoxia cell material has been enhanced significantly at pH 5 and 6 when immobilized in a polysilicate matrix. New binding sites having a greater binding strength with a lower availability have been observed for the binding of UO2+2 after immobilization of the cultured biomaterial. However, chemical alteration of the cell material resulting from this immobilization process has not been observed. The chemical environment of the binding sites responsible for the binding of UO2+2 in immobilized and free D. innoxia cell material has been demonstrated to be different. This difference results from the immobilization of the cell material within a polysilicate matrix.
Signal Enhancement Technique for Internal Reflection Spectroscopy
Authors: Lowry Stephen R. , May Timothy E. , Bornstein Aharon
Published: June 2005

The use of chalcogenide glass for internal reflection spectroscopy (IRS) is described. Chalcogenide glass is a material normally used in infrared fiber-optic systems. A key feature of this concept is the ability to create a tapered section in the IRS crystal in order to increase the interaction with the sample. A liquid cell with integral fiber is described, and its performance as an IRS element is discussed. Several features of the fiber and cell holder are shown to increase sensitivity and allow for an inexpensive sampling accessory.
Optimized Gated Detection for Lifetime Measurement over a Wide Range of Single Exponential Decays
Authors: Waters P. Dean , Burns David H.
Published: June 2005

Optimal estimation parameters are determined for the rapid lifetime determination technique (RLD) of fitting an exponential model to luminescence decay data that exhibit a wide range of lifetimes. Optimization of the lifetime estimate by this technique depends on only two parameters—period of integration and separation between the periods of integration. Luminescence quenching experiments produce a range of decay lifetimes. Selection of a fixed set of measuring parameters to determine lifetime throughout the entire range can simplify instrumentation and result in enhanced computation speed. The measuring parameters must be optimized to yield the best estimation of each lifetime in the range. The errors in measured lifetime for the RLD technique are investigated for a wide range of luminescence decays. Optimal separation and periods of integration for the modified RLD technique are found by modeling a set of simulated decay data with different lifetimes. Results from the simulation are then compared to similar measurements of oxygen-quenched luminescence decay. Agreement between simulation and quenching data is good.
Mid-Infrared Spectra from Near-Infrared Spectra Using Partial Least-Squares
Authors: Lew Raymond , Balke Stephen T.
Published: June 2005

In this novel application of a multivariate method, partial least-squares (PLS) was used to generate mid-infrared (MIR) spectra (rather than selected concentrations) from near-infrared (NIR) spectra. The NIR spectra were obtained by in-line monitoring of a molten polymer blend of polyethylene with polypropylene during extrusion. Off-line MIR spectra of blends were used to calibrate the PLS method. Then PLS was used to generate the MIR absorbance spectrum of a 50:50-by-weight blend not included in the calibration set from its NIR spectrum. The synthesized MIR spectrum agreed very well with a directly measured one. The exception was absorbance peaks which were so strong that they apparently represented responses that were nonlinear with respect to concentration. Although more evaluation work has yet to be done, these results are encouraging, and they indicate that NIR interpretation may readily borrow the strengths of MIR interpretation both qualitatively and quantitatively.
S/N Enhancement of Raman Spectra Using an Interactive Filter
Authors: Mann Charles K. , Vickers Thomas J.
Published: June 2005

The use of an interactive filter for smoothing Raman spectra is described. It is applied by fitting a polynomial to a limited range of data in a spectrum using the least-squares criterion. It provides a variable bandpass with very sharp cutoff without generating ringing artifacts. Its use is demonstrated in tailoring of the filter bandpass to the requirements of individual spectral features, in detection of weak peaks in a noisy spectrum, and in detection of minor component signals when these are superimposed on major component signals.
Normal and Malignant Human Colonic Tissues Investigated by Pressure-Tuning FT-IR Spectroscopy
Authors: Wong Patrick T. T. , Lacelle Suzanne , Yazdi Hossein M.
Published: June 2005

Infrared spectra of the epithelial, the connective, the mucosa, and the malignant tissues of the human colon have been measured as a function of pressure. Infrared spectra of collagen proteins have also been measured and compared with the connective tissue. The infrared spectra of different types of colon tissues exhibit significantly different patterns. With these specific infrared patterns, the tissue types of the colon can be differentiated unambiguously. Many structural changes at the molecular level from normal epithelium to malignant tumor have been derived from the spectral features of these two related tissues. These structural changes in carcinogenesis of the colon are comparable with those in other human cancers. The present results suggest that determination of these infrared spectra may be applied to the rapid identification of normal tissue types of the colon and evaluation of colon cancer.
Surface Analysis of Excimer-Laser-Treated Polyethylene-Terephthalate by Surface-Enhanced Raman Scattering and X-Ray Photoelectron Spectroscopy
Authors: Lippert Th. , Zimmermann F. , Wokaun A.
Published: June 2005

Silver and gold island films have been evaporated onto various polymer surfaces; the samples were characterized by surface-enhanced Raman spectroscopy (SERS), UV-visible spectroscopy, and x-ray photoelectron spectroscopy (XPS). Among the series of investigated polymers, the SERS spectra recorded on stretched polyethylene-terephthalate (PET) foils are unique with respect to resolution and intensity; the signal strengths are comparable to those observed in enhanced resonance Raman scattering. This exceptional behavior is attributed to the semicrystalline nature of the investigated material, and to the preferred interaction of the deposited silver with carbonyl groups of the polymer. The formation of a metal/polymer bond was established by the observation of corresponding bands in the XPS spectrum. Upon melting or amorphization of PET, the SERS intensities are reduced; this result is attributed to a decrease in the metal/polymer bond strength, due to changes in orientation of the phenyl rings and of the carbonyl groups on the polymer surface. The PET surfaces have been modified by excimer laser irradiation at the wavelengths of 308 and 248 nm. The characteristic laser-induced structuring of the surface, as revealed by scanning electron microscopy, is related to the biaxial stretching applied during production of the PET foils, and has been studied for various orientations of the samples and different laser fluences. As a consequence of irradiation, a loss of oxygen is detected by a decrease of the C 1 s XPS bands assigned to carbon atoms with singly or doubly bound oxygen, and by an overall decrease of the oxygen-to-carbon ratio. The surface polarity is observed to decrease, as accompanied by a red shift of the absorption maximum for silver island films deposited onto the irradiated surfaces. SERS spectra recorded on these samples are weaker in intensity, as compared to those recorded on untreated PET foils. This decrease is interpreted in terms of partial amorphization of the sample accompanied by polymer reorientation, loss of the preferred anchoring sites for nucleation of silver islands, and changes in the surface structure and morphology.
Wavelength Calibration of a Multichannel Spectrometer
Authors: Tseng Ching-Hui , Ford Joseph F. , Mann Charles K. , Vickers Thomas J.
Published: June 2005

A readily automated procedure for wavelength calibration of multichannel spectrometers is described. Once applied, line positions can be read from the multichannel display with good accuracy and precision for any spectrometer setting. The procedure uses Ne atomic lines as wavelength standards. A novel apodization procedure is used for accurate measurement of the pixel positions of the neon lines. Raman line positions can be determined with an average error of less than 0.2 cm−1.
Identification of Wood Species by Acoustic-Resonance Spectrometry Using Multivariate Subpopulation Analysis
Authors: Mills Timothy P. , Jones Angela , Lodder Robert A.
Published: June 2005

The identification of wood species remains an issue in restoration involving rare, old, or disguised wood parts. Precise restoration is required in reconditioning the works of designers such as Frank Lloyd Wright, and a quick, reliable, and nondestructive method of identification facilitates this restoration. Acoustic-resonance spectrometry (ARS) is an analytical method using interferences in resonance signals across a range of frequencies. Combined with multivariate analysis techniques, ARS is a solution to the problem of identifying wood species. Subpopulation detection analysis of samples of 26 different wood species achieved complete differentiation among species ( p = 0.01). The number of bootstrap replications of the spectral data has a significant effect on differentiation among the woods, as does the type of spectral filtering prior to subpopulation analysis. Acoustic-resonance spectrometry outperforms near-IR spectrometry by a wide margin in identification of the same wood species.
Spectroscopic Investigations of Malaria Pigment
Authors: Brémard C. , Girerd J. J. , Kowalewski P. , Merlin J. C. , Moreau S.
Published: June 2005

Malaria pigment is generated during the growth of the intraerythrocytic parasite plasmodium. This compound is postulated as a product of haemoglobin degradation and consists of an unknown iron porphyrin compound and an apoprotein. We report here a new spectroscopic investigation on the porphyrin component of intact malaria pigment obtained from in vitro cultures of Plasmodium falciparum without any previous chemical or biochemical treatment of the sample. We demonstrate the use of resonance Raman microspectrometry, electron paramagnetic resonance spectrometry, and magnetic susceptibility measurements that show the iron porphyrin moiety of the malaria pigment to be a high-spin monomeric iron(III) protoporphyrin hydroxide.
Determination of Organics on Metal Surfaces by Raman Spectroscopy
Authors: Tseng Ching-Hui , Mann Charles K. , Vickers Thomas J.
Published: June 2005

Detection limits of about 1 g/m2 are demonstrated for the Raman determination of two organic materials, polydimethylsiloxane and dimethyl methylphosphonate, on an aluminum surface. A fiber-optic-based system is used. A large sample area is scanned to overcome heterogeneity in sample coverage. Measurements are made without use of an internal standard. Results are reported for both a Hadamard transform technique with argon-ion laser excitation and a conventional spectrometer with diode laser excitation.