bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessing children's inference generation: What do tests of reading comprehension measure?
Authors: Bowyer‐Crane Claudine , Snowling Margaret J.
Published: July 2005

Background. Previous research suggests that children with specific comprehension difficulties have problems with the generation of inferences. This raises important questions as to whether poor comprehenders have poor comprehension skills generally, or whether their problems are confined to specific inference types.

Aims. The main aims of the study were (a) using two commonly used tests of reading comprehension to classify the questions requiring the generation of inferences, and (b) to investigate the relative performance of skilled and less‐skilled comprehenders on questions tapping different inference types.

Sample. The performance of 10 poor comprehenders (mean age 110.06 months) was compared with the performance of 10 normal readers (mean age 112.78 months) on two tests of reading comprehension.

Method. A qualitative analysis of the NARA II (form 1) and the WORD comprehension subtest was carried out. Participants were then administered the NARA II, WORD comprehension subtest and a test of non‐word reading.

Results. The NARA II was heavily reliant on the generation of knowledge‐based inferences, while the WORD comprehension subtest was biased towards the retention of literal information. Children identified by the NARA II as having comprehension difficulties performed in the normal range on the WORD comprehension subtests. Further, children with comprehension difficulties performed poorly on questions requiring the generation of knowledge‐based and elaborative inferences. However, they were able to answer questions requiring attention to literal information or use of cohesive devices at a level comparable to normal readers.

Conclusions. Different reading tests tap different types of inferencing skills. Less‐skilled comprehenders have particular difficulty applying real‐world knowledge to a text during reading, and this has implications for the formulation of effective intervention strategies.
Epistemological beliefs and approaches to learning: Their change through secondary school and their influence on academic performance
Authors: Cano Francisco
Published: July 2005

Background. In recent decades, two lines of research, phenomenographic and meta‐cognitive, have examined students' approaches and epistemological beliefs about learning. To date there has been very little research describing the change in epistemological beliefs in European secondary students, or analysing interrelationships between epistemological beliefs and approaches in order to explain their influence on academic performance.

Aims. The first aim of this investigation is to analyse the change in epistemological beliefs and learning approaches in secondary students as they progress through their studies. The second aim is to examine the effects of epistemological beliefs on learning approaches, and learning approaches on academic performance.

Sample. About 1,600 Spanish students, boys and girls, from several secondary schools took part in the study. They were between 12 and 20 years old and their average age was 14.79 years.

Methods. Measures of epistemological beliefs (EQ: Epistemological Questionnaire), learning approaches (LPQ: Learning Process Questionnaire), and academic performance were obtained. Confirmatory factor analysis was used to examine the dimensionality of the EQ and LPQ questionnaires. In order to achieve our two aims, different statistical techniques were used: MANOVA and ANOVA for our first aim, and structural equation modelling for our second aim.

Results. Throughout secondary education epistemological beliefs undergo change, becoming more realistic and complex, and deep‐approach scores decline significantly. It was shown that, as predicted, epistemological beliefs influenced academic achievement directly, and also indirectly via students' learning approaches.

Conclusions. Our findings point to two conclusions. First, epistemological beliefs and learning approaches change as pupils advance in their studies. Second, the relationship between epistemological beliefs and academic achievement is mediated by approaches to learning.
The effect of peer collaboration on children's problem‐solving ability
Authors: Fawcett Lillian M. , Garton Alison F.
Published: July 2005

Background.A Vygotskian framework links cognitive change to collaborative interaction with a more competent partner whereas a Piagetian perspective supports the view that cognitive conflict arising from peer interaction leads to cognitive change.

Aims.The study investigated the effect of collaborative learning on children's problem‐solving ability and whether differences in knowledge status or the use of explanatory language were contributing factors.

Sample.Participants were 100 Year 2 children (aged between 6 and 7 years), from schools in high socio‐economic areas, who individually completed a pre‐ and post‐test comprising a block sorting task.

Method.During the experimental phase, children completed a card sorting activity, either individually or in same‐gender dyads. The dyads consisted of same or different ability children who operated under either a ‘talk’ or ‘no‐talk’ condition.

Results.It was found that children who collaborated collectively obtained a significantly higher number of correct sorts than children who worked individually. However, post‐testing indicated that only those children of lower sorting ability who collaborated with higher sorting ability peers showed a significant improvement in sorting ability from pre‐test scores. In addition, it was found that when analysis was limited to this particular group, only those children who were required to explain the sort for their partner to carry out improved significantly from pre‐ to post‐test.

Conclusion.It is suggested that perhaps the two theoretical positions are not as mutually exclusive as they are often portrayed. Implications of these findings for teachers and children's learning are also discussed.
Explaining individual differences in scholastic behaviour and achievement
Authors: Petrides K. V. , Chamorro‐Premuzic Tomas , Frederickson Norah , Furnham Adrian
Published: July 2005

Background. This paper presents results from the first wave of a longitudinal study examining the effects of various psychosocial variables on scholastic achievement and behaviour at school.

Aims. The main aim is to investigate the nature and strength of the effects of major individual difference dimensions on important outcome variables at school level, including academic performance, truancy, and antisocial behaviour.

Samples. Data were collected from a sample of 901 pupils on verbal ability (as a proxy for cognitive ability), personality traits, and a number of behavioural indices, including academic performance at 14 and 16 years, number of authorized and unauthorized absences, and exclusions from school due to antisocial conduct.

Methods. During the first stage of the study, seven schools participated in all three phases. Teachers administered a questionnaire battery in class according to a detailed protocol. Additional data were collected from school archives.

Results. Analysis of the data through multi‐group (male and female puplis) structural equation modelling indicated a very strong effect of verbal ability on academic performance. Extraversion and psychoticism were negatively related to academic performance, although their effects were weak and moderated by gender. Verbal ability, extraversion, and psychoticism predicted absenteeism, truancy, and exclusions from school due to disruptive conduct. The latter three were negatively associated with academic performance.

Conclusions. The findings indicate that major individual difference dimensions like verbal ability and personality traits, have a strong influence on important outcome variables at school level, including academic performance, truancy, and antisocial behaviour. Without fully acknowledging the crucial role of individual differences in shaping behaviour and achievement at school, the timely identification of pupils at risk, and the development of effective intervention schemes will be difficult.
Pupils' liking for school: Ability grouping, self‐concept and perceptions of teaching
Authors: Ireson Judith , Hallam Susan
Published: July 2005

Background. Research indicates that affective aspects of development provide a basis for autonomous learning. Pupils' liking for school may be a useful indicator of their relationships with teachers and the school.

Aims. The aim of the research reported in this paper is to establish the properties of a measure of pupils' liking for school and to examine associations between this measure, pupils' experiences in lessons, their self‐concepts and the amount of setting implemented in school.

Sample. A stratified sample of 45 mixed secondary comprehensive schools was selected for the research. Schools represented a variety of ability‐grouping practices in the lower school (Years 7–9), from completely mixed‐ability to setting in all academic subjects. All Year 9 pupils were included in the sample.

Methods. Pupils completed a questionnaire containing items on their self‐concept, liking for school, and their perceptions of teaching in English, mathematics, and science. Data on pupils' gender, ethnic origin, social disadvantage and attainment was also collected.

Results and conclusions. The properties and correlates of scales indicating pupils' liking for school and their perceptions of teaching in English, mathematics, and science are established. Liking for school is greater among girls, pupils with higher academic self‐concepts, and those with more positive perceptions of teaching. Pupils are more positive about teaching they experience in English than in mathematics or science. When other variables are statistically controlled, there is no significant effect of the extent of ability grouping in the school as a whole. Affective aspects of learning should not be neglected in the drive to raise standards.
Reception class predictors of literacy skills
Authors: Simpson Jennifer , Everatt John
Published: July 2005

Background. In the last decade, there has been a growing interest, both in the UK and abroad, in developing early screening tests for dyslexia that can be used with very young children. In addition to measures of literacy achievement, such screening tests typically aim to identify underlying difficulties, such as phonological deficits, that might hinder a child's educational progress. The Dyslexia Early Screening Test (DEST; Nicolson & Fawcett, 1996) is an example of such a test that combines attainment and diagnostic indicators.

Aim. The study reported assessed the ability of the DEST to predict future literacy skills in contrast with the prediction afforded by school‐based measures, such as letter knowledge.

Sample. Participants were 45 boys attending a reception class, with a mean age of 4.87 years at the start of the study and 6.63 years at the end.

Methods. Measures of literacy skills, phonological awareness, verbal memory, motor skill, and auditory processing were assessed using the DEST as the initial screening tool at Phase 1. Measures of letter knowledge, non‐word reading, and rhyme judgment were taken at Phase 2. Phase 3 measures, 14 months after the start of the study, comprised single‐word reading and spelling. At Phase 4, some 22 months after the beginning of the study, measures of reading and spelling ability were assessed again.

Results. Individual subtests of the DEST were more predictive of later literacy skills than the global screening test's score (the ‘at risk quotient’). Better predictors were the DEST subtest of sound order and rapid automatized naming, together with the school attainment measure of letter knowledge.

Conclusions. Although some DEST subtests did offer predictors of future literacy skills, school‐based measures of letter knowledge may be equally valid as assessment measures. Additionally, the results question the usefulness of combining measures to form an ‘at risk’ index of future literacy difficulties, particularly in the age range assessed.
The social skills problems of victims of bullying: Self, peer and teacher perceptions
Authors: Fox Claire L. , Boulton Michael J.
Published: July 2005

Background. A small number of prior studies have found that victims of school bullying tend to exhibit poor social skills. Few of these have examined this issue from multiple perspectives, and there has been a focus on a restricted range of social skills.

Aims. To determine the extent to which self, peers, and teachers regard victims as having poorer social skills than non‐victims across 20 behaviours/competencies.

Sample. A convenience sample of 330 pupils aged between 9 and 11 years (162 girls and 168 boys) provided self‐report and peer‐report data. They were drawn from 12 classes from 6 junior schools in the UK. Additionally, 11 of the class teachers provided data.

Method. Three separate methods were employed and in each case, participants were provided with 20 short statements that described a different social skill: (1) participants who were classified as either ‘victims’ or ‘non‐victims’ (using peer nominations) rated themselves on a 3‐point scale in terms of how like them each description was, (2) participants were asked to think of a victim and a non‐victim in their class and to rate both of these people on each description, and (3) teachers were asked to rate a previously identified victim and a non‐victim from their class on each description.

Results. Using a direct discriminant function analysis of the self‐ratings, six of the social skills items were found to discriminate between victims and non‐victims, and the discriminant function was able to correctly classify 80% of the participants. For 18 of the items, peer ratings indicated significantly more pronounced social skills problems for victims than for non‐victims. Teacher ratings were significant for eight of the social skill items, and in each case, victims were rated as having greater problems.

Conclusion. The finding that victims are perceived by three different sources to have poor social skills has important implications for interventions to support victims of bullying.
Spatial Emission Characteristics of a Capillary-Burner Excitation Source for a Flame Infrared Emission (FIRE) Radiometer
Authors: Ravishankar S. , Tilotta David C. , Busch Kenneth W. , Busch Marianna A.
Published: July 2005

A complete mapping of the lateral and radial intensities of the 4.4- μm emission (antisymmetric CO2 stretch) resulting from the direct introduction of carbon dioxide, a homologous series of aliphatic hydrocarbons, and benzene into a hydrogen/air combustion flame supported on a capillary burner has been carried out. Both concentrated (99% methane, ethane, propane, and butane) and dilute (1% methane, ethane, propane, and benzene) hydrocarbons were studied. Flame profiles produced by the introduction of carbon dioxide were used to indicate the effects of local variations in source temperature and carbon dioxide number density in the absence of combustion. The radial profiles produced by the introduction of carbon dioxide and the hydrocarbons revealed a considerable amount of off-axis emission, believed to result from a zone of low temperature along the central vertical axis of the burner. Combustion of analyte appeared to be a diffusion-controlled process. For aliphatic hydrocarbons, combustion produced nearly quantitative amounts of carbon dioxide, provided the flame was not overloaded. For benzene, combustion produced particulate carbon, and the resulting blackbody emission was not strictly related to analyte concentration or carbon number. Blackbody emission may also result from the incomplete combustion of longer chain aliphatic hydrocarbons (propane and butane), if the burner is overloaded.
Infrared Spectral Search for Mixtures in Large-Size Libraries
Authors: Lo Su-Chin , Brown Chris W.
Published: July 2005

A routine for searching large spectral libraries with spectra of mixtures is presented. The dimensionality of a 3169-compound library is reduced to 12% of its original size by using Fourier transform compression and principal component analysis. A principal component regression is performed and used as a prefilter in selecting spectra having features (and chemical groups) similar to those of the unknown mixture. A dot-product metric is then used to identify a target component from the subgroup formed by the prefilter. This is followed by the application of an adaptive filter to remove the similarity of the target component from the subgroup and from the unknown mixture; the search is repeated on the modified data. Successive applications of the adaptive filter will produce minimum residuals if the correct identifications are made. Once the residuals are minimized, a similarity index is calculated to determine the closeness of the unknown mixture spectrum to a spectrum reconstructed from the library spectra. Four out of five two- and three-component spectra were correctly identified. One of the two components in the fifth mixture was correctly identified, and the residual values flagged the improper identification of the second component. After the adaptive filter was applied to the entire library, the second component was correctly identified. Results for this new algorithm are compared to those from four more traditional search routines, which were only completely successful on one of the unknown mixtures.
Stimulated Raman Gain Detected by Photothermal Beam Deflection for Selective Determination of Organic Compounds
Authors: Lai Edward P. C. , Harris Joel M.
Published: July 2005

The efficiency of the stimulated Raman gain scattering (SRGS) in liquids is sufficiently high to make the phenomenon useful as a means of chemical analysis. Quantitative and qualitative studies of stimulated Raman gain detected by photothermal probe beam deflection are presented with a major simplification in instrumentation for generating the Stokes probe beam. This technique is evaluated for the detection and quantitation of a model chlorinated hydrocarbon, 1,1,1-trichloroethane. With a very modest laser pulse energy of 1.5 mJ (average power of 1.5 mW) and a pathlength of 10 cm, the technique is useful for the noninvasive, real-time monitoring of SRGS-active compounds at the 10 mM level. Selectivity against 1,1,2-trichloroethane, 1,2-dichloroethane, trichloroethylene, ethylbenzene, and benzene is excellent. Direct identification and simultaneous determination of individual compounds in process and effluent streams could be attained without sampling, separations, or other pretreatment procedures.
Examination of Packaged Consumer Goods by Using FT-Raman Spectrometry
Authors: Compton David A. C. , Compton Senja V.
Published: July 2005

The feasibility of obtaining FT-Raman spectra of consumer products inside clear polymeric packaging is described. It is possible to obtain high-quality spectra of the sample without removing it from the package, thus enabling quality-control checks to be performed on a final product. Examples are shown for three pharmaceutical preparations and one food product.
Infrared Study of Benzaldehyde and 4-Substituted Benzaldehydes in Carbon Tetrachloride and/or Chloroform Solutions: The Carbonyl Group
Authors: Nyquist Richard A. , Settineri Sam E. , Luoma Davin A.
Published: July 2005

The carbonyl stretching mode of 4- x-benzaldehydes increases in frequency as the mole % CHCl3/CCl4 decreases and as the value of σP− or σRO for the 4- x atom or group increases. Other functional groups such as OH, NO2 and CN are also affected by interaction with the CHCl3 and/or CCl4 solvent system. Other solvents may interact differently with each functional group so that, say, vC=O vs. σP−, σRO, or solvent acceptor numbers (AN) may not correlate in a uniform manner in all solute/solvent systems.
Normal and Surface-Enhanced Raman Investigations of Carbon Materials
Authors: Tadayyoni M. Azar , Dando Neal R.
Published: July 2005

Raman spectroscopy is rapidly developing as a nondestructive technique for the surface characterization of carbon materials. An advantage of Raman analyses is that the substrate surface may be both spatially localized (determined by the position and diameter of the probe beam) and effectively depth profiled (comparing normal and surface-enhanced Raman data) without the need to employ surface-disruptive sample preparation techniques. The efficacy of normal and surface-enhanced Raman spectroscopy for investigating carbon surfaces is demonstrated by comparing Raman and SERS spectra of monolithic graphitic carbon and 7- μm graphite fiber. The data obtained indicate the existence of more disordered carbon at surfaces as compared to the bulk, exemplify the need for empirically determining innocuous silver deposition conditions (for SERS), and demonstrate the utility of Raman spectroscopy for investigating carbon materials.
Multispectral Hadamard Transform Raman Microscopy
Authors: Liu Kei-Lee K. , Chen Li-Heng , Sheng Rong-Sheng , Morris Michael D.
Published: July 2005

The Hadamard transform Raman microscope equipped with a two-dimensional video detector is inherently capable of obtaining images at several different Raman frequencies simultaneously. In this communication, we describe the necessary software to exploit this multispectral capability. We apply multispectral imaging to polymer laminates and to removal of artifacts from Raman images.
Hydrolyzed Polyacrylamide/Chromium(III) Acetate Gel Chemistry
Authors: Tackett James E.
Published: July 2005

Proton NMR and visible spectroscopy are used to investigate the chemistry of hydrolyzed polyacrylamide/chromium acetate gels. Color changes in conjunction with HNMR are used to monitor chromium acetate hydrolysis, and HNMR is used to characterize Polyacrylamide in solution and to monitor increases of free acetate and decreases of polymer backbone proton and amide proton resonances during gel formation. The data indicate that chromium acetate hydrolysis is halted by polymer coordination. The polymer cross-linking reaction appears to be a simple replacement of chromium(III) coordinated acetate groups on the chromium(III) trimer by polymer carboxylate groups.
Selective Determination of Pentafluorobenzyl Ester Derivatives of Carboxylic Acids by GC Using Microwave Plasma and Mass Selective Detection
Authors: Brill Jeffrey H. , Narayanan Bikshandarkoil A. , McCormick John P.
Published: July 2005

A highly selective, sensitive method for determination of carboxylic acids in water has been developed that is based on fluorine-selective gas chromatography (GC) detection of pentafluorobenzyl ester derivatives. The atmospheric-pressure helium microwave-induced plasma detector is well suited for fluorine-specific detection of these derivatives, which were well resolved by capillary GC and displayed a characteristic fragmentation behavior when examined by GC-mass selective detection. For demonstration purposes, a number of carboxylic acids, ranging from C1 to C20, were examined and found to be derivatized with yields greater than 90%, and a sample of creek water was examined for its carboxylic acid content.
Optical Sectioning Raman Microscopy
Authors: Govil Anurag , Pallister David M. , Chen Li-Heng , Morris Michael D.
Published: July 2005

We describe the use of Hadamard transform Raman microscopy to acquire optically sectioned images of crystals of benzoic acid. Nearest-neighbor deblurring is used to reject out-of-focus information and sharpen the Raman images obtained from the crystal.
Flow Injection Preconcentration Coupled with Direct Sample Insertion for Inductively Coupled Plasma Atomic Emission Spectrometry
Authors: Moss P. , Salin E. D.
Published: July 2005

A flow injection (FI) preconcentration system has been coupled with a direct sample insertion (DSI) system for inductively coupled plasma atomic emission spectrometry (ICP-AES). The FI system provides a preconcentration factor of approximately 30. The DSI detection limit improvement, as compared to conventional nebulization detection limits, is element specific and ranges between 10 and 130 when a cup specifically designed for liquid work is used. The FI-DSI hybrid provides detection limit improvements ranging between 140 and 1200 for the elements tested—Cu, Pb, and Zn. Precision of the FI-DSI-ICP system averages 4% RSD for these three elements. FI processing time is 6.0 minutes with the use of 5-mL injection volumes. The system offers considerable potential for further improvement by increasing the injection volume and improving the interface to the DSI.
Determination of Uranyl in Aqueous Solutions Using a Fiber-Optic-Based, Time-Resolved Luminescence Sensor
Authors: Varineau Pierre T. , Duesing Rich , Wangen Lawrence E.
Published: July 2005

The use of time-resolved luminescence measurements is an effective way to determine a wide range of uranyl concentrations in aqueous samples. We have coupled this technique with the use of a remote optical sensing device, a “flow optrode,” by using fiber-optic cables in order to probe for uranyl in aqueous solutions. The flow optrode incorporates a Nation membrane through which UO2+2 can diffuse into a reaction/analysis chamber which contains phosphoric acid, a reagent which enhances the uranyl luminescence intensity and excited-state lifetime. The excited-state lifetime measurement provides information on the chemical environment within the sensor. Anionic quenchers are prohibited from entering the analysis cell because they cannot diffuse through the membrane. Fluorescing organic interferences can be eliminated by analyzing the emission signal at several microseconds after laser excitation. We were able to determine uranyl over a concentration range of 10−4 to 10−9 M using the flow optrode sensor.
FT-IR Analysis of Jojoba Protein Conformations in D2O
Authors: Abbott Thomas P. , Wolf Walter J. , Wu Y. Victor , Butterfield Royden O. , Kleiman Robert
Published: July 2005

FT-IR methods in the literature for determining the secondary structure of proteins in D2O solution involve a curve-fitting step which is somewhat subjective. In an effort to reduce the subjectivity of curve-fitting of protein amide carbonyl absorbances, initial estimations of peak heights and widths were used which were independent of operator judgment. Other restrictions on the curve-fitting procedure were imposed so that different operators would arrive at values for secondary structure consistent with each other and with the literature for papain, hemoglobin, ribonuclease, myoglobin, and alpha-chymotrypsin. This goal was partially achieved by the preliminary method described in this paper. The method was then applied to jojoba proteins and a jojoba protein isolate, the 2S fraction. The jojoba 2S fraction is predominantly beta-structure (51%) and retains its beta-structure in pD 13 solution or at neutral pD when its disulfide linkages are reduced and alkylated. However, dissolving the reduced alkylated protein in pD 13 solution gives a totally random structure by infrared analysis.
FT-IR Analysis of the Monomer Sequence Distribution of Styrene-Acrylonitrile Copolymers
Authors: Sargent M. , Koenig J. L. , Maecker N. L.
Published: July 2005

The infrared spectra for a series of random styrene-acrylonitrile (SAN) copolymers of various compositions were analyzed to determine the dependence of the individual spectral peaks on the copolymer composition. Correlations were established to relate changes in the peak positions and intensities to changes in the copolymer composition and monomer sequence distribution. It was found that a number of peaks shift to higher frequencies as the amount of acrylonitrile in the SAN copolymer is increased while others shift to lower frequencies. It was also found that some peak positions are unaffected by changes in the copolymer composition. The intensities of the spectral peaks were also analyzed as a function of the copolymer content by plotting changes in the intensity values against the number fraction of each of the possible monad, dyad, and triad structures. A peak was then determined to result from a given microstructure if there exists a positive linear relationship between the peak intensity and the number fraction of this microstructure.
Investigations of a Metastable Dependence on the Ionization of Sputtered Species in Neon Glow Discharges
Authors: Serxner D. , Smith R. L. , Hess K. R.
Published: July 2005

Optical investigations of a low-pressure (0.3–4.0 Torr), low-current (1–4 mA), coaxial geometry glow discharge operating with neon as the fill gas are described. Studies were designed to experimentally illustrate the role of neon metastable atoms in the population of selected excited-state ion levels of copper atoms sputtered from a brass cathode. Methane was employed as a quenching agent to reduce the neon metastable population, and ion emission signals from a variety of copper ion transitions showed a decrease in intensity corresponding to the introduction of methane to the plasma. In addition, with variations in discharge pressure, a correlation between the number of neon metastables and the strength of the ion emission signals was observed. These results provide evidence that Penning ionization is an important mechanism for the ionization of sputtered atoms in neon glow discharges, similar to the results obtained for an argon system. Finally, a brief comparison of the neon and argon systems was made which showed the neon discharge gas to be more efficient at populating the monitored copper ion levels. This is most likely due to the higher energy of the neon metastables, which permits the direct population of these ion levels from the copper ground state.
CO2-Based Thermometry of Supercritical Water Oxidation
Authors: Brown Michael S. , Steeper Richard R.
Published: July 2005

We have demonstrated the suitability of CO2 Raman spectra as a thermometry probe of the fluid mixtures encountered in supercritical water oxidation. Measured temperature accuracies of ±6% are presented. Measurements were made of the v1 2 v2 Fermi resonance features of CO2 in a supercritical water environment. Over the temperature range of interest to researchers of supercritical water oxidation, ∼400–650°C, hot bands appear in the Raman spectrum of CO2 with sufficient spectral intensity to serve as a convenient measure of the fluid temperature. We have analyzed these hot bands by taking the ratio of their integrated intensity with the integrated intensity of the fundamental. Over the temperature range of 390 to 540°C, the intensity ratio of the first pure hot band feature to the fundamental of v1 shows a very nearly linear dependence on temperature. The experimental ratio measurements are well explained by standard Raman theory if the Fermi resonance is accounted for. As discussed, the CO2 spectral line shape is affected by the high pressure ( P > 22.1 MPa) used in supercritical work, but these changes do not affect the extraction of a fluid temperature from the spectra.
Development, Characterization, and Application of a Double-Waveguide Evanescent Sensor
Authors: Lal Sundeep , Yappert M. Cecilia
Published: July 2005

A double-waveguide evanescent sensor has been developed and characterized. A fraction of the evanescent field (λ e = 488 nm) generated at the core ( nc = 1.48)/cladding ( ncl = 1.45) interface of a glass optical fiber penetrates into the cladding and the polymeric jacket ( nj = 1.54) coated onto the cladding. Fluorescence is excited within the jacket and, due to the higher refractive index of the jacket, the emission is totally internally reflected within it. The emission (λ em = 605 nm) has been collected with the use of lateral and front-end geometries. The sensor has been used to determine iodine in gas and liquid phases using an indirect approach. Iodine reacts with unsaturated sites of the polymer and absorbs the fluorescence, causing a reduction in the fluorescence background. The rate of fluorescence reduction is proportional to the concentration or partial pressure of iodine in the sample.
An IBM PC Based Computer Program for the Analysis of Infrared Spectra
Authors: Yang Min J. , Yang Paul W.
Published: July 2005

A computerized infrared interpreter has been developed on an IBM personal computer (PC) running under the Microsoft disk operating system (DOS). Based on the original Merck Sharp & Dhome Research Laboratory Program for the Analysis of InfRared Spectra (PAIRS), this infrared interpreter, PC PAIRS+, is capable of analyzing infrared spectra measured from a wide variety of spectrophotometers. Modifications to PAIRS now allow the application of both artificial intelligence and library searching techniques in the program. A new algorithm has been devised to combine the results from the library searching and the PAIRS program to enhance the dependability of interpretational data. The increased capability of this infrared interpreter along with its applicability on a personal computer results in a powerful, general-purpose, and easy-to-use infrared interpretation system. Applications of PC PAIRS+ on petrochemical samples are described.
Infrared and Nuclear Magnetic Resonance Spectra-Structure Correlations for Anisoles
Authors: Nyquist R. A.
Published: July 2005

Spectra-structure correlations are presented for anisoles using IR, NMR, and chemical parameter values which aid in the spectra-structure identification of unknown materials. Spectra-structure correlations also aid in assigning carbon-13 chemical shifts to the correct carbon atom in anisoles.
Characterization of a Laser Plasma in a Pulsed Magnetic Field. Part II: Time-Resolved Emission and Absorption Studies
Authors: Mason Kelly J. , Goldberg Joel M.
Published: July 2005

Temporally resolved emission and absorbance measurements were made in order to investigate the dynamic effects of a high-intensity pulsed magnetic field on a laser plasma. Temporally resolved emission studies were spatially resolved so that the effects of the magnetic field on plasma propagation both along and normal to the magnetic field could be probed. The mechanism of interaction of the field was investigated by observing plasma emission in spatial zones most likely to be influenced by an induced secondary current in the plasma. Spatial and temporal discrimination of emission enhancements indicated that radial compression was due to static magnetic field interactions with the laser plasma and that mild Joule-heating from the small induced current was most likely responsible for emission enhancements later in time. Spatially integrated absorbance measurements in the decaying plasma showed a decrease in absorbance as a result of the magnetic confinement; this is attributed to an increased rate of condensation of the atoms in the vapor cloud produced by the pinched plasma. More efficient coupling of energy from the magnetic field to the plasma would require low-pressure operation in a controlled atmosphere and/or a pulsed magnetic field having a greater d B/d t.
Characterization of an Atomospheric-Pressure Parallel-Plate Capacitively Coupled Radio-Frequency Plasma
Authors: Huang Degui , Blades M. W.
Published: July 2005

A new design for a radio-frequency, atmospheric-pressure, parallel-plate capacitively coupled plasma (CCP) which uses water-cooled electrodes is described. Four different sizes of quartz tubes were compared with respect to spatial emission features for support gas and analyte species. Torches studied had the following inside dimensions: a 1-mm capillary tube with round cross section, a 2 × 4 mm tube, a 4 × 4 mm tube, and a 6 × 6 mm tube. Relative emission intensities of near-infrared lines for F, Cl, Br, I, C, N, and O atomic and ionic lines excited with the use of the He-CCP are tabulated. The detection limits range from 10 to 78 pg/s.
Surface-Enhanced Raman Spectroscopy of Nucleic Acid Compounds and Their Mixtures
Authors: Thornton John , Forcé R. Ken
Published: July 2005

Surface-Enhanced Raman Spectroscopy (SERS) has been used to characterize nucleic acid compounds—such as free bases, mononucleotides, and dinucleotides—to study the viability of the technique to analyze mixtures of the various compounds and to see whether the SERS properties of the dinucleotides are sequence dependent. To these ends, silver colloids (sols) prepared by citrate reduction methods have been used as the enhancing surface. We have found that some components show stronger enhancement than others and that the more strongly enhanced species tend to dominate spectra of equimolar mixtures. In addition, the relative intensities of the spectra of mixtures are different from the spectra of the individual components added together. This is likely due to competition among the analyte molecules for enhancing surface sites and to the surface potential of the enhancing agent favoring certain components over others. Despite these occurrences, the spectral features of various compounds are additive, and the spectrum of one component can be subtracted from the spectrum of the mixture with the features of the others left intact. Also, the enhancement of the various components is pH dependent, and is different from an aqueous medium to an electrophoresis gel medium. SERS shows considerable promise as a tool for characterizing mixtures of nucleic acid compounds.
Evaluation of a Tantalum-Tip Electrothermal Vaporization Sample Introduction Device for Microwave-Induced Plasma Mass Spectrometry and Atomic Emission Spectrometry
Authors: Evans E. Hywel , Caruso Joseph A. , Satzger R. Duane
Published: July 2005

An integrated electrothermal vaporization/microwave-induced plasma device has been shown to be a viable source for atomic emission and mass spectrometry. The tantalum-tipped electrothermal vaporizer ensured that no analyte condensation occurred during transport to the plasma and facilitated the formation of an annular helium plasma. Detection limits obtained with atomic emission spectrometry were 0.6, 21, and 2400 pg for Ag, Pb, and I, respectively, and those obtained with mass spectrometry were 0.03, 0.09, 0.75, and 1.5 pg for Ag, Cd, Pb, and Br, respectively. Detection limits were blank limited due to contaminants in the materials used in construction of the furnace. The current study was limited to high-volatility elements.
Reheating of a Laser-Produced Plasma by a Second Pulse Laser
Authors: Uebbing J. , Brust J. , Sdorra W. , Leis F. , Niemax K.
Published: July 2005

Focused radiation of a Nd:YAG laser was used for ablation and production of free sample atoms from electrically conducting and nonconducting solids for analytical purposes. The microplasmas were generated in an argon buffer gas atmosphere at reduced pressure. In order to increase the intensities of analyte lines the microplasmas were reheated by a second Nd:YAG laser after the process of atomization was completed. It is demonstrated for aluminum and manganese in glass and steel samples and for magnesium and manganese in glass, copper, and aluminum that by internal standardization a common calibration curve can be obtained.
Use of the Optogalvanic Effect to Examine the Laser Power Dependency of Several Excitation/Ionization Mechanisms in a Hollow Cathode Discharge
Authors: Petrucci G. A. , Winefordner J. D.
Published: July 2005

Several examples of the relationship between resonant and nonresonant collisional ionization and photoionization, laser intensity, and the ability to saturate both resonant and nonresonant transitions are illustrated. The effects of energy deficit and effective energy overshoot in determining the dominant ionization pathway are also discussed. An approximation of the lifetime of the virtual level is made, and its relationship to the probability of two-photon nonresonant absorption is discussed. Finally, the theoretical model described above is fitted to the optogalvanic data for two single-step resonance transitions of Ne to determine the applicability of the model developed for flame LEI to the hollow cathode discharge environment (under our experimental conditions) and to obtain estimates of the collisional ionization rate constant, k2i, and photoionization cross section, σ2i.
The Effects of Moisture and Gases on the Room-Temperature Fluorescence and Phosphorescence of Model Aromatic Compounds Adsorbed on Filter Paper
Authors: Citta L. A. , Hurtubise R. J.
Published: July 2005

Water, oxygen, and air were investigated for their abilities to quench the room-temperature fluorescence (RTF) and room-temperature phosphorescence (RTP) of the protonated forms of benzo[f]quinoline (B[f]QH+) and benzo[h]quinoline (B[h]QH+), and α-naphthoflavone. As with earlier studies, H2O was found to be a more potent quencher of RTP than O2. However, both species were able to quench RTP. A simple method was developed for reporting the percentage decrease in RTP or RTF for a given quencher, and thus easy comparisons could be made among the component contributions to the overall quenching of the RTF and RTP signals. The RTP quenching data for the three phosphors were found to fit an equation of the form, Y = aXb. This equation allowed some conclusions to be made about the interactions responsible for the quenching of RTP by moisture. Also, it was found that RTF was much less sensitive to H2O and O2 quenching than was RTP.
Measurements of Aerosol Particle Sizes from a Direct Injection Nebulizer
Authors: Wiederin Daniel R. , Houk R. S.
Published: July 2005

Photographs and laser-scattering measurements showed that a direct injection nebulizer (DIN) produced a finer aerosol with a narrower drop size distribution than that for a conventional glass concentric nebulizer when both were operated at the same liquid and nebulizer gas flow rates. The droplets from the DIN were slightly larger, however, than those leaving a Scott-type spray chamber with a glass concentric nebulizer. The droplets from the DIN had a Sauter mean diameter of ∼7 μm and a 90% mass diameter of 11–16 μm. The droplet size distribution became narrower and shifted to lower diameters as the aerosol gas flow rate increased.
Laser-Excited Fluorescence Studies of Matrix-Induced Errors in Inductively Coupled Plasma Spectrometry: Implications for ICP-Mass Spectrometry
Authors: Hobbs Steven E. , Olesik John W.
Published: July 2005

Laser-induced Sr ion fluorescence measurements were made as a function of nebulizer gas flow rate and applied power in the presence and absence of concomitant species for comparison to previously published ICP-MS data. The fluorescence data are used to assess the contribution of matrix effects in the plasma itself to errors observed in ICP-MS due to the presence of concomitant species. Significant matrix effects do appear to originate in the plasma. Reconsideration of ambipolar diffusion shows that the matrix effects in the plasma should not be dependent on the mass of the analyte or concomitant species. Experimental, radially resolved measurements confirm the lack of mass dependence.
Side-on Photomultiplier Gating System for Thomson Scattering and Laser-Excited Atomic Fluorescence Spectroscopy
Authors: Hanselman David S. , Withnell Ronald , Hieftje Gary M.
Published: July 2005

A normally-off gating circuit for use with side-on photomultipliers (PMTs) has been developed for use in Thomson scattering and laser-excited atomic fluorescence spectroscopy. Switching of dynodes 1 and 5 provides cutoff ratios greater than 7 × 105 and gating times on the order of 6 ns. The gated PMT signal responds linearly up to anode currents of −6.6 mA, a saturation current roughly two orders of magnitude greater than in continuous (dc) operation. The gating circuit has an aperture width variable from 40 ns to 1.3 μs and the ability to operate at triggering rates up to 10 kHz.
Characteristics of the LOMEP Line-Narrowing Method
Authors: Kauppinen J. K. , Moffatt D. J. , Hollberg M. R. , Mantsch H. H.
Published: July 2005

Several intrinsic characteristics of the Line Shape Optimized Maximum Entropy Linear Prediction (LOMEP)‡ procedure as a line-narrowing method are discussed, and examples are presented that demonstrate its application to gas-phase IR absorption spectra, as well as to NMR spectra. An algorithm is introduced which determines the reliability of the Linear Prediction (LP) procedure on a given set of data and, hence, the reliability of the LOMEP output data.
Characteristic Vector Regression Analysis: An Effective Method for Data Reduction of the Spectra Database
Authors: Wang H. , Zhu Y. , Zhang L. , Wang Z.
Published: July 2005

On the basis of characteristic vector analysis (CVA) and multiple regression analysis (MRA), a method of characteristic vector regression analysis (CVRA) is proposed for the data reduction of the spectra database. The high correlation among the spectra in the spectra database ensures the feasibility of the method. Studies of Gaussian functions and spectra of groundwaters, as well as spectra of soils and plants, with evidence of a high reduction ratio and good retrieval precision, show the effectiveness of the method. Better retrieval precision can be achieved by combining the characteristic vectors with the mean spectrum for the reconstruction of the original spectra. The method can be extended to perform spectral classification and spectral background correction.
Fundamental Aerosol Studies with an Ultrasonic Nebulizer
Authors: Tarr Matthew A. , Zhu Guangxuan , Browner Richard F.
Published: July 2005

Laser scattering particle size measurements, together with aerosol and vapor mass transport, were used to characterize the aerosol generated with an ultrasonic nebulizer (USN). Several fundamental aspects of the ultrasonic primary and tertiary aerosols were studied, including drop size distributions, Sauter mean diameters, analyte mass transport, and solvent mass transport. These characteristics were compared with comparable data obtained with a concentric, all-glass (Meinhard type) pneumatic nebulizer. It was found that the ultrasonic nebulizer generated a primary aerosol which had a substantially broader size distribution than the pneumatic nebulizer. However, overall both analyte and solvent mass transport for the USN were much greater than for the pneumatic nebulizer.
Flame Atomic Absorption Spectrometric Determination of Cadmium, Cobalt, and Nickel in Biological Samples Using a Flow Injection System with On-Line Preconcentration by Co-Precipitation without Filtration
Authors: Welz Bernhard , Xu Shukun , Sperling Michael
Published: July 2005

Cadmium, cobalt, and nickel at ng/g to μg/g levels in plant and animal tissue reference materials and at μg/L levels in blood and urine were determined by flame atomic absorption spectrometry. The analyte elements were preconcentrated and separated from the bulk of the matrix by on-line co-precipitation with the hexamethylene ammonium hexamethylene dithiocarbamate iron(II) chelate complex in a flow injection system. The precipitate was collected in a knotted reactor made from 150-cm-long, 0.5-mm-i.d. Microline tubing without using a filter. The precipitate was dissolved in methyl isobutyl ketone and introduced directly into the nebulizer-burner system of an atomic absorption spectrometer. Ascorbic acid in an HC1/KC1 buffer was added on-line in order to reduce iron(III) to iron(II) because of its much better efficiency as a collector for trace elements. Reagent concentrations were optimized so that at least 200 mg/L of iron and 15 mg/L of copper could be tolerated in the sample solution without causing significant interferences. The portion of the analyte retained in the collector was about 70% for cadmium and 50% for cobalt and nickel. Enrichment factors of 24, 19, and 20 were obtained for cadmium, cobalt, and nickel, respectively, with the use of a 40-s co-precipitation time, resulting in enhancement factors, including the effect of the organic solvent, of 52, 43, and 52, respectively. The detection limits (3 σ) for cadmium, cobalt and nickel were 0.15, 1.3, and 1.5 μg/L, respectively, and the precision was 1.5% RSD for 10 μg/L Cd, 2.7% RSD for 50 μg/L Co, and 1.8% RSD for 50 μg/L Ni. The analytical results obtained for a number of standard reference materials and control samples were in good agreement with the certified or recommended values.