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  • Articles  (135,645)
  • Springer  (119,986)
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  • 1990-1994  (115,388)
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  • Chemistry and Pharmacology  (84,178)
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  • Energy, Environment Protection, Nuclear Power Engineering  (23,504)
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  • Articles  (135,645)
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  • 1
    Electronic Resource
    Electronic Resource
    Generation of Hydrogen Gas as a Result of Drilling Within the Saturated Zone (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water monitoring & remediation 14 (1994), S. 0 
    Details
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Hydrogen gas was discovered within the steel casing above standing water in a percussion-drilled borehole on the Hanlord Site in south-central Washington state. In situ measurements of the borehole fluids indicated anoxic, low-Eh (〈-400 mV) conditions. Ground water sampled from adjacent wells in the same formation indicated that the ground water was oxygenated. H2 was generated during percussion drilling, due to the decomposition of borehole waters as a result of aqueous reactions with drilled sediment and steel from the drilling tools or casing. The generation of H2 within percussion-drilled boreholes that extend below the water table may be more common than previously realized. The ambient concentration of H2 produced during drilling was limited by microbial activity within the casing-resident fluids. H2 was generated abiotically in the laboratory, whereby sterilized borehole slurry samples produced 100 times more H2 than unsterilizcd samples. It appears that H2 is metabolized by microorganisms and concentrations might be significantly greater if not for microbial metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6592.1994.tb00492.x
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  • 2
    Electronic Resource
    Electronic Resource
    Increased Thermal-Pulse Flowmeter Resolution by Adding a Packer and Computer (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water monitoring & remediation 14 (1994), S. 0 
    Details
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Measurement accuracy was increased by nearly one order of magnitude by outfitting the thermal-pulse flowmeter (TFM) with an inflatable packer. To accurately measure slow water velocities in boreholes greater than 15 cm diameter, it is necessary to divert borehole fluids through the TFM by inflating a packer. During calibration it was noted that the TFM's accuracy decreased as the borehole diameter increased. With Lhe packer inflated the TFM has a useful flow measurement range of 0.08 to 15 L/min (with flow velocities of 0.24 ± 0.012 cm/inin to 45.7 ± 0.61 cm/min, respectively, in 20-cm-diameter pipe), compared to 0.8 to 57 L/min for a packcrless TFM. A computer interlace was added to the TFM to provide a real-time graphical display of the differential voltage output from the TFM, a running mean and standard deviation of the pulse-response time, and a mean flow rate and velocity based on calibration curve fits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6592.1994.tb00497.x
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  • 3
    Electronic Resource
    Electronic Resource
    National Water Quality Monitoring Strategy Update (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water monitoring & remediation 14 (1994), S. 0 
    Details
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6592.1994.tb00486.x
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  • 4
    Electronic Resource
    Electronic Resource
    An Assessment of the Nguyen and Finder Method for Slug Test Analysis (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water monitoring & remediation 14 (1994), S. 0 
    Details
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The Nguyen and Pinder method is one of four techniques commonly used for analysis of response data from slug tests. Limited field research has raised questions about the reliability of the parameter estimates obtained with this method. A theoretical evaluation of this technique reveals that errors were made in the derivation of the analytical solution upon which the technique is based. Simulation and field examples show that the errors result in parameter estimates that can differ from actual values by orders of magnitude. These findings indicate that the Nguyen and Pinder method should no longer be a tool in the repertoire of the field hydrogeologist. If data from a slug test performed in a partially penetrating well in a confined aquifer need to be analyzed, recent work has shown that the Hvorslev method is the best alternative among the commonly used techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6592.1994.tb00490.x
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  • 5
    Electronic Resource
    Electronic Resource
    Ground Water Monitoring Statistics Update: Part II: Nonparametric Prediction Limits (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water monitoring & remediation 14 (1994), S. 0 
    Details
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Nonparametric prediction limits can be useful statistical tools for ground water monitoring at facilities regulated under RCRA Subtitle C. Subtitle D. and similar regulations. New, exact tables arc presented for both “1 of m” plans (m chances to gel one observation inbounds at each of r monitoring wells to avoid a statistically significant increase) and “California” plans (first or all of the next m-1 observations inbounds at each well). The tables provide per-constituent significance levels (false positive rates) as a function of the background sample size n. m. r, the prediction limit (the largest or the next to largest, background observation), and the confirmatory resampling plan selected.When used in a monitoring program, future observations from several wells are compared with a prediction limit obtained from a common background sample. The table significance levels therefore depend critically on having IID (independent and identically distributed) observations. In particular, the false positive rate computations are not valid, and the procedures should not be used, with constituents whose measurements exhibit inherent spatial or systematic temporal variability.Recent U.S. EPA guidance explicitly encourages controlling facility-wide false positive rates over both constituents and wells. Nonparametric prediction limits, particularly with California resampling plans, will have greater difficulty in meeting the new. lower per-constituent false positive rate goals than previous ones, especially if many constituents are involved. Nonetheless, nonparametric prediction limits remain superior to other commonly used procedures for dealing with data with high proportions of nondctects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6592.1994.tb00494.x
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  • 6
    Electronic Resource
    Electronic Resource
    The Client-Consultant Relationship (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water monitoring & remediation 14 (1994), S. 0 
    Details
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6592.1994.tb00461.x
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  • 7
    Electronic Resource
    Electronic Resource
    Wellhead Protection Workshops: What Have We Learned? (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water monitoring & remediation 14 (1994), S. 0 
    Details
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6592.1994.tb00465.x
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  • 8
    Electronic Resource
    Electronic Resource
    Rapid Assessment of Trichloroethylene in Ground Water (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water monitoring & remediation 14 (1994), S. 0 
    Details
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: On-site analysis of trichloroethylene (TCE) in aqueous samples by head- space sample preparation and gas chromatography (HS/GC) provides for quick and precise concentration estimates. This analytical approach is well suited for the on-site determination of volatile organic compounds (VOCs) in a variety of sample matrices, including ground water and saturated and unsatured soils. For these reasons, HS/GC can be used to establish analyte concentrations on a near real time basis to help select appropriate casing material during monitoring well installation. This application and the collection of multiple well samples during sampling events facilitates the hydrogeological site interpretation and the formulation of remediation strategies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6592.1994.tb00472.x
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  • 9
    Electronic Resource
    Electronic Resource
    Vertical Distribution and Partitioning of Chromium in a Glaciof luvial Aquifer (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water monitoring & remediation 14 (1994), S. 0 
    Details
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The vertical distribution and partitioning (between the solid and aqueous phase) of chromium in a glaciofluvial aquifer in northeastern Connecticut were assessed. Most of the chromium (99 percent of its mass) is bound to the soil. Retardation is primarily the result of binding to organic matter and adsorption to iron oxide coatings. However, other attenuation mechanisms also appear to be significant. If the degree of chromium binding observed here is representative of other chromium contaminated sites, pump-and-treat remediation will not remove the vast amount of chromium from the subsurface. However, most of the chromium may be immobile, and removal may not be required following the initial pumping to remove the mobile fraction. Further knowledge of the mechanisms that bind chromium to the soil, their reversibility, and their kinetics is essential to developing effective remediation strategies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6592.1994.tb00476.x
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  • 10
    Electronic Resource
    Electronic Resource
    Discussion of “What You Don't Find Isn't There, Or Is It? (or The absence of proof is not proof of absence),”Ground Water Monitoring & Remediation, v. 14, no. 1, pages 79-83, Winter 1994. (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water monitoring & remediation 14 (1994), S. 0 
    Details
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6592.1994.tb00480.x
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  • 11
    Electronic Resource
    Electronic Resource
    Discussion of “What You Don't Find Isn't There, Or Is It? (or The absence of proof is not proof of absence),”Ground Water Monitoring & Remediation, v. 14, no. 1, pages 79-83, Winter 1994. (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water monitoring & remediation 14 (1994), S. 0 
    Details
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6592.1994.tb00481.x
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  • 12
    Electronic Resource
    Electronic Resource
    Surfactant-Induced Reductions in Soil Hydraulic Conductivity (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water monitoring & remediation 14 (1994), S. 0 
    Details
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Surfactant solutions are being proposed for in situ flushing of organic contaminants from soils and aquifers. The feasibility of surfactant additives in remediation may depend in large part on how these chemicals affect the hydraulic conductivity of the porous media. While there is evidence in the literature of conductivity loss during surfactant flushing (Miller et al. 1975; Nash et al. 1987), there has been little research on quantifying the process for unconsolidated sediments. Surfactant-affected hydraulic conductivity reductions were measured in two soils (Teller loam and Daugherty sand). Testing was done with eight surfactants at a variety of concentrations (10-5 to 10-l mole/kg), surfactant mixtures, and added solution electrolytes. The Teller was also tested with its organic matter removed. Maximum hydraulic conductivity decreases were 47 percent for the sand and more than two orders of magnitude for the loam. Surfactant concentrations, surfactant mixtures, soil organic content, and added solution electrolytes all affected the degree of conductivity reduction. Results indicate that surfactant-affected hydraulic conductivity losses should be considered prior to in situ remediation and may preclude surfactant use in some fine grain soils.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6592.1994.tb00112.x
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  • 13
    Electronic Resource
    Electronic Resource
    Comprehensive State Ground Water Protection Programs: A Preliminary Examination of Two States (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water monitoring & remediation 14 (1994), S. 0 
    Details
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6592.1994.tb00088.x
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  • 14
    Electronic Resource
    Electronic Resource
    Correction (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water monitoring & remediation 14 (1994), S. 0 
    Details
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6592.1994.tb00094.x
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  • 15
    Electronic Resource
    Electronic Resource
    Field Trapping of Subsurface Vapor Phase Petroleum Hydrocarbons (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water monitoring & remediation 14 (1994), S. 0 
    Details
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Soil gas samples from intact soil cores were collected on adsorbents at a field site, then thermally desorbed and analyzed by laboratory gas chromatography (GC). Vertical concentration profiles of predominant vapor phase petroleum hydrocarbons under ambient conditions were obtained for the zone directly above the capillary fringe. Water and residual phase weathered aviation gasoline were present in this region of the profile.The sampling, trapping, and GC methodology was effective in most respects. Reproducibility, trapping, and desorption efficiency were generally satisfactory, and different sorbent tubes gave similar results. A minor shortcoming of the method occurred with the most volatile compound, 2,3-dimcthylbutane, which was poorly retained during several weeks of storage lime and was also poorly desorbed.Vapor phase concentrations of predominant hydrocarbon compounds all increased with depth at one sampling location. At a more highly contaminated location, concentrations of highly volatile compounds increased with depth while concentrations of less volatile compounds remained constant or decreased, possibly indicating distillation effects. Scatier in the data was attributed to heterogeneities in water and residual phase distribution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6592.1994.tb00096.x
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  • 16
    Electronic Resource
    Electronic Resource
    PCR SSCP REVEALS HAPLOTYPE RELATED POLYMORPHISM OF PERB 1: A NEW MARKER FOR MHC β BLOCK TYPING (1994)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 21 (1994), S. 0 
    Details
    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Many new Major Histocompatibility Complex (MHC) genes have been discovered in the last 5 years. Defining the polymorphism of these new genes may elucidate their function and their relevance to diseases with MHC associations. Polymerase chain reaction and single stranded conformation polymorphism (PCR SSCP) analyses were used to detect sequence polymorphisms of PERB1 demonstrated by comparing the available genomic sequence of four haplotypes. This study showed that PCR SSCP of PERB 1 is reproducible. In addition, PERB1 alleles segregate within families together with MHC haplotypes. Typing results from the Forth Asia and Oceania Histocompatibility Workshop (4AOHW) cell panel indicate that the identified polymorphisms of PERB 1 are ‘haplotypic’, i.e., unrelated individuals carrying the same MHC ancestral haplotypes carry the same PERB1 SSCP pattern. Interestingly, PERB1 SSCP patterns allow the distinction of ancestral haplotypes which share HLA-B serological specificities, such as HLA-B44 and therefore this analysis can be used to further define MHC haplotypes and thus to improve our understanding of the evolution of this complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1744-313X.1994.tb00216.x
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  • 17
    Electronic Resource
    Electronic Resource
    THE ASSOCIATION BETWEEN COELIAC DISEASE, DERMATITIS HERPETIFORMIS AND CERTAIN HLA-ANTIGENS IN ICELANDERS (1994)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 21 (1994), S. 0 
    Details
    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Twenty-eight cases of coeliac disease (CD) and seven of dermatitis herpetiformis (DH) have been verified in Iceland. Standard serological techniques were used for HLA typing. Twenty-five individuals with CD were typed, 21 (84%) of whom carried DR3, DQ2. Twelve of these 25 (48%) had DR3, DR7, DQ2, which makes them possibly homozygous for DQ2, and suggests that homozygosity of DQ2 increases the risk for CD. The four DH patients that were typed all had HLA-B8, DR3, DQ2. It is concluded that CD and DH are associated with DR3, DQZ in Icelanders.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1744-313X.1994.tb00218.x
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  • 18
    Electronic Resource
    Electronic Resource
    T CELL RECEPTOR DELTA LOCUS POLYMORPHISM IN RHEUMATOID ARTHRITIS (1994)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 21 (1994), S. 0 
    Details
    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: In order to identify new susceptibility markers for Rheumatoid Arthritis (RA), we analysed the dinucleotide repeat polymorphism at the T cell receptor delta locus (TCRD) in 65 RA patients and 99 healthy Belgian controls. A significant under-representation of the A4-A5 TCRD genotype was observed in the RA population.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1744-313X.1994.tb00221.x
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  • 19
    Electronic Resource
    Electronic Resource
    ANNOUNCEMENTS (1994)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 21 (1994), S. 0 
    Details
    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1744-313X.1994.tb00224.x
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  • 20
    Electronic Resource
    Electronic Resource
    THE FIRST HLA ANTHROPOLOGICAL STUDY IN THE KUWAITI POPULATION (1994)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 21 (1994), S. 0 
    Details
    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: HLA antigens of the Kuwaiti population are not as well characterized as those of other international ethnic groups. We present results for HLA typing of Kuwaiti individuals using commercial Biotest sera. Six hundred and seventy one Kuwaiti were typed for HLA-A, -B, -C antigens and 399 were typed for HLA-DR, -DQ antigens. Antigen frequency and gene frequency were computed for each phenotype observed. The antigens with the highest frequencies were HLA-A2, A1 and A3; B5, B12 and B7; Cw″4 and Cw-l; DR52, DR5, DR3 and DR7; DQ1 and DQ2. HLA haplotypes with strong linkage disequilibrium and characteristic of Kuwaiti population are A2-B5, A1-B8, B7-DR7 and B8-DR3. A comparison study with other populations is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1744-313X.1994.tb00200.x
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  • 21
    Electronic Resource
    Electronic Resource
    MOLECULAR ANALYSIS OF CYP21 GENE MUTATIONS CARRIED ON HLA-B14 POSITIVE HAPLOTYPES (1994)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 21 (1994), S. 0 
    Details
    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: HLA-B14 positive haplotypes have increased frequencies in a group of patients with puberty disorders, IgA deficiency and cancer of the ovary. Clinical investigations demonstrated that all these patients have high values of 170H progesteron after the ACTH test which suggests an alterated function of 21 hydroxylase enzyme. In order to investigate whether these B14 positive haplotypes carry the same CYP21 mutation in the various diseases and controls, we have amplified by polymerase chain reaction (PCR) the sections of CYP21B gene which include amino acid positions 172 and 281 where typical mutations are known to occur in 21 hydroxylase deficiency. The presence or absence of the defined mutations was tested by oligonucleotide hybridization using oligonucleotides, labelled with DIG-ddUTP, designed to hybridize with the mutated or with the normal sequence. It was found that regardless of whether the subject tested was a patient or a healthy control the mutation at position 281 was found in all cases carrying HLA-B14, DR1 haplotype. Interestingly, this mutation does not seem to be in association with HLA-B14, DR7 haplotype.These findings suggest that CYP21 gene plays a role in all these differing diseases although it must be stressed that there may be alternative explanations for the observed data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1744-313X.1994.tb00204.x
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  • 22
    Electronic Resource
    Electronic Resource
    Gm and Km PHENOTYPE FREQUENCIES IN CHILDREN WITH CHRONIC ACTIVE HEPATITIS (CAH) B VIRUS INFECTION (1994)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 21 (1994), S. 0 
    Details
    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Patients with CAH, extrahepatic HBV manifestation and healthy children were studied for presence of Gm 1,2,3,10,21 factors and Km 1 factor. Significantly higher frequency of Gm (1, 2, 3, 10, 21) phenotype was shown in CAH group as compared with the other two groups. Relationship between Km factors and examined groups was not found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1744-313X.1994.tb00207.x
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  • 23
    Electronic Resource
    Electronic Resource
    British Society for Histocompatibility and Immunogenetics (1994)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 21 (1994), S. 0 
    Details
    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1744-313X.1994.tb00211.x
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  • 24
    Electronic Resource
    Electronic Resource
    HLA-DQA1 AND DQB 1 ALLELE AND GENOTYPE CONTRIBUTION TO IDDM SUSCEPTIBILITY IN AN ETHNICALLY MIXED POPULATION (1994)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 21 (1994), S. 0 
    Details
    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: HLA-DRB1, DQA1 and DQB1 alleles have been determined in 42 families with one IDDM proband and 64 healthy controls, by oligotyping (PCR-SSO) using primers and probes from the XI International Histocompatibility Workshop. A positive DRB1 *03 and DRB1 *04 association with the disease was observed, whereas DRB 1*11 and DRB 1 *07 showed negative association but 19% of patients carried DRB1 alleles different to DRB 1 *03 or *04. When single alleles were considered, DQA1 *03 showed the strongest association with susceptibility to the disease (RR = 8.2, Pc = 0.00001) but this association was outgrown by 2 and 3 allele combinations, with genotype DRB 1 *04-DQA 1 *03-DQB1*0302/DRB1*03- DQA 1*0501- DQB 1*0201 showing the strongest association (RR = 28, Pc = 0.002). Application of the relative predispositional effect (RPE) method to our data, revealed a further susceptibility risk provided by the DRB1*13-DQA1*0102-DQB 1*0604 haplotype once DR3 and DR4 haplotypes were removed. When DQA1-DQB1 genotypes were analysed for presence of Arg 52 (DQ α) and absence of Asp 57 (DQ β), genotypes SS/SS were found significantly increased in diabetics. Interestingly, one of the strongest associations with the disease was observed with the DQA 1*03-DQB 1*0201 combination encoded mainly by genes in trans (RR = 11.7 Pc = 0.00004). These observations and their comparison with DR-DQ haplotypes in more homogeneous ethnic groups support the stronger influence of the DQ molecule rather than the individual DR or DQ alleles in the susceptibility to IDDM. They also emphasize the need for detailed HLA haplotype studies in non-Caucasian and ethnically mixed populations to gain further insight into the nature of genetic and environmental factors contribution to autoimmunity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1744-313X.1994.tb00213.x
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  • 25
    Electronic Resource
    Electronic Resource
    TNF Nco-I RFLP IS NOT AN INDEPENDENT RISK FACTOR IN RHEUMATOID ARTHRITIS (1994)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 21 (1994), S. 0 
    Details
    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The human TNF genes are located within the MHC class-III region on chromosome 6. The presence or absence of an Nco-I restriction site in the 5’ non-coding sequence of the TNFβ gene defines two alleles (TNFB*1 and TNFB*2). The segregation of these alleles has been associated with levels of TNFα or TNFβ production in systemic lupus erythematosis (SLE), insulin-dependent diabetes mellitus (IDDM) and in healthy control individuals.Rheumatoid arthritis (RA) is characterized by high levels of TNFα within the synovial fluid and to address the question of whether this could be brought about by a genetic predisposition to high TNF production by RA individuals, we examined the distribution of this Nco-I polymorphism in 98 healthy volunteers and 123 patients with active rheumatoid arthritis. No difference was observed between the normal and RA groups with respect to haplotype segregation or allelic frequency. Furthermore, no difference was observed between DR4+ or DR4- individuals in the control or RA groups.These data demonstrate that the high level of TNFα seen in the joints of RA patients is unlikely to be due to a genetic predisposition of these patients to high TNFα production, as defined by the TNF Nco-I restriction fragment length polymorphism (RFLP).
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    NOMENCLATURE FOR FACTORS OF THE HLA SYSTEM, 1994 (1994)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 21 (1994), S. 0 
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    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1744-313X.1994.tb00222.x
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    INDICATIONS OF AN AUTOIMMUNE COMPONENT IN LP(a) ASSOCIATED DISORDERS (1994)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 21 (1994), S. 0 
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    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The exceptionally strong independent association found between Lp(a) lipoprotein [Lp(a)] levels and atherosclerotic disorders indicate that Lp(a) is a factor of considerable importance in the pathogenesis of atherosclerosis. The association between Lp(a) and diabetes, rheumatoid arthritis and renal diseases suggest that Lp(a) may be involved in immunological mechanisms.Lp(a) has a great tendency to aggregate and bind to glucosaminoglycans, fibrin and fibronectin and is preferentially retained in the extracellular matrix during development of atherosclerosis and is in vitro phagocytosed by macrophages, probably as small aggregates. It was previously found that the Lp(a) level is significantly related to the HLA class II genotype in male patients with early coronary artery disease. In this paper additional results of interleukin determinations in relation to HLA type and Lp(a) levels are presented and discussed. It is suggested that an autoimmune process, perhaps triggered by a concomitant intracellular infection may occur, especially in patients with inherited high Lp(a) levels in combination with certain inherited HLA class II genotypes.
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    URL: http://dx.doi.org/10.1111/j.1744-313X.1994.tb00201.x
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    DPB1 LOCUS PCR-RFLP TYPING OF THE FOURTH ASIA-OCEANIA HISTOCOMPATIBILITY WORKSHOP CELL PANEL REVEALS A NOVEL DPB1 ALLELE (1994)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 21 (1994), S. 0 
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    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: DPB1 locus typing of the 155 cell 4AOHW panel was performed using a PCR-RFLP method. Ambiguity of allele assignment was resolved by amplification using sequence-specific primers. Of the 150 cells for which typings were achieved, three exhibited unusual restriction enzyme fragment patterns, suggesting the possibility of novel DPB1 alleles. Sequence analysis revealed one allele present in the currently reported 46, one novel allele (4AOHW/107) not present among the 46, and one from a non-human primate which is being investigated. Twenty-six (26) of the 34 10IHW cells have been studied previously by cDNA RFLP, and strong haplotypic associations have been demonstrated between DPA1 and DPB1 locus alleles. It is proposed that exploitation of intron polymorphisms marking haplotypes will be an integral part of future DPB 1 typing as a ‘first-pass’ stratification process to minimize the requirement for sequence-based methods to definitively assign DPB 1 alleles.
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    DISTRIBUTION OF HLA-A*28 ALLELES IN A SPANISH POPULATION (1994)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 21 (1994), S. 0 
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    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: DNA oligotyping was used to determine HLA-A28 subtypes in 25 unrelated Caucasian individuals living in or around Seville, Spain. Results showed that HLA-A*6802 was the most frequent allele, found in 14 individuals (53.8%), followed by HLA-68.3, which was present in eight subjects (30.8%), and both combined represented 84.6% of A28+ individuals in the area. The HLA-A*6801 allele was found in three individuals (11.5%), whereas HLA-A*6901 was present in one subject only (3.8%). Results indicate that the distribution of HLA-A28 alleles can vary among different Caucasoid populations. In this way, the high frequency obtained for A*6802 supports previous studies suggesting that the HLA-A*6802 allele was prevalent in people of the Mediterranean basin, in contrast to A*6801, prevalent in northern European populations.
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    ANNOUNCEMENTS (1994)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 21 (1994), S. 0 
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    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1744-313X.1994.tb00185.x
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    MHC IN SYSTEMIC LUPUS ERYTHEMATOSUS: A STUDY ON A KUWAITI POPULATION (1994)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 21 (1994), S. 0 
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    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: HLA alleles were studied in Kuwaiti patients with Systemic lupus erythematosus (SLE). Although significant association of B5, B8, and DR3 has been reported in the literature, the most common phenotype for our patients is A3, DR2 as susceptible alleles and DQ1 as a protective gene.
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    URL: http://dx.doi.org/10.1111/j.1744-313X.1994.tb00171.x
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    SEROLOGICAL IDENTIFICATION OF A NEW HLA-B7 VARIANT ANTIGEN –HLA-B7QUI (1994)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 21 (1994), S. 0 
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    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A new HLA-B antigen, HLA-B7Qui that appears to be a variant of HLA-B7 has been identified. This antigen, which is HLA-Bw6 associated, reacts with approximately two-thirds of cytotoxic antisera stimulated by HLA-B7 or B27 that lack a B27 or B7 component, respectively. All anti-B7+27 antisera (stimulated by either B7 or B27) react with B7Qui as do most B22-stimulated sera possessing a B7 component. However, sera stimulated by B60, with or without a B7 component, fail to react with B7Qui.Family studies show the B7Qui allele to be unique to the haplotype –HLA-A32 CW6 B7Qui Bf*S C4A*6 C4B*1 DR11 DQ7 (GL02). Six Caucasoid subjects on the panel of 6861 HLA-typed potential bone marrow donors have this antigen (phenotype frequency, 0.08745%; gene frequency, 0.04473%). Work undertaken during the 11th International Histocompatibility Workshop (Reekers et al., 1992) showed that B7Qui has the same isoelectric point as HLA-B702 and HLA-B703 (Bpot) and that B7Qui is distinct from the HLA-B7 variants B703, B7SL, BDT, B7x40, BRI, and B41v.
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    GENE FREQUENCY AND LINKAGE DISEQUILIBRIUM ANALYSIS OF HLA-DRB1*04 HAPLOTYPES IN A SOUTH WALES POPULATION (1994)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 21 (1994), S. 0 
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    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: HLA-DRB1*04 allele frequencies have been determined in 184 HLA-DR4-positive unrelated blood donors from the South Wales area, using group-specific polymerase chain reaction (PCR) amplification and hybridization with sequence-specific oligonucleotide probes, PCR amplification with sequence-specific primers, and PCR single-strand conformation polymorphism analysis.Eight of the fifteen known HLA-DR4 sequences were detected in this study. Linkage disequilibrium analysis of HLA-DRB1 *04 and HLA-B, -DR and -DQ alleles revealed distinct haplotypic associations for all the major alleles detected in this population, including the novel linkage of HLA-B55 with DRB1*0407.These results are relevant to the role of HLA-DRB 1*04 haplotypes in determining allogeneic histocompatibility and disease susceptibility.
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    A CLASS I cDNA FROM SPAFAS LINE-11 CHICKENS (1994)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 21 (1994), S. 0 
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    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A chicken MHC class I (B-F) cDNA from SPAFAS line 11 embryonic liver tissue was isolated and characterized by nucleotide sequencing. Comparing this sequence with previously described B-FcDNAs highlights clustered nucleotide substitutions in exon 3, encoding amino acids located on the a-helical region of the α2 domain.
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    Sankey Brook Catchment Study (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: The Sankey Brook catchment lies in the heart of the Mersey basin. As part of a major study into development issues in the Sankey Brook catchment, a hydraulic model was constructed and successfully used to simulate the river system and to assist in the derivation of discharge control policies.The background to the study and the subsequent hydrological and hydraulic modelling are described, particularly in relation to the more complex systems in the lower reaches of Sankey Brook.
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    URL: http://dx.doi.org/10.1111/j.1747-6593.1994.tb01154.x
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    The Reconstruction of Sewage-Treatment Works in Osaka City (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Osaka has nearly completed its sewerage system, and twelve sewage-treatment works are now in operation. Tsumori and Ebie works, the two oldest, were commissioned in 1940. For these works, full-scale reconstruction has just commenced.This paper reports on the reconstruction of the Tsumori works, and outlines the plan for future reconstruction of the city's sewage-treatment works.
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    URL: http://dx.doi.org/10.1111/j.1747-6593.1994.tb01158.x
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    Setting Effluent Consent Standards (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: The paper outlines how consent standards are normally calculated in Scotland for both river systems and tidal waters. A background is given to the reason why a more statistical approach has been adopted in England and Wales where the use of combining distribution methods is more widespread. Comparison of the two approaches is made, particularly with regard to their potential impact on resources required for treatment plants, and also the problems of taking enforcement action. The setting of standards under the EC urban waste water treatment Directive is considered where, in addition to the implications of primary, secondary and more stringent treatment, consideration is given to storm-sewage overflows and industrial discharges.
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    URL: http://dx.doi.org/10.1111/j.1747-6593.1994.tb01162.x
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    An Assessment of the Impact of Inland Surface Water Input to the Bacteriological Quality of Coastal Waters (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: The introduction of ultraviolet disinfection in Jersey has achieved significant improvements in water quality. However, bathing waters in St Aubin's Bay and shellfish flesh have failed to comply with microbial standards. Streams and seepages from coastal structures were investigated as potential indicator organism sources (total and faecal coliforms, faecal streptococci). Seepages were an unimportant bacterial source as concentrations were low. Geometric mean concentrations in streams were up to four orders of magnitude higher than in final sewage-treatment works effluent, and concentrations increased significantly at high stream discharge. Rainfall-induced pulses of poor water quality occurred two to three times per week during the 1993 summer season. Natural discharges from island catchments thus contribute significantly to the bacterial load received at the coast, especially during high flow events. These observations have implications for other UK and European schemes using tertiary disinfection technology to attain water quality targets in coastal waters.
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    The Application of Risk Assessment to Contaminated Land: The British Gas Experience (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: British Gas owns over 900 sites within the UK with a total land area in excess of 5500 ha. Many of the sites are former gasworks, chemical works or associated holder stations.Although serious attempts were made to remove contamination during the last three decades, the operating and demolition standards previously considered to be adequate may no longer be acceptable and may have given rise to sites with the potential to contaminate adjacent land, surface waters and ground-water. As a result, further actions may now be required on these sites to reach new environmental standards, thereby reducing any chance there may be of legal liability on the Company.This paper describes the advantages and disadvantages of several qualitative and quantitative risk-assessment methods which can be used to prioritize potentially contaminated sites for further investigation. The use of site investigation data to accurately target risk reduction in site remediation proposals is also discussed.
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    URL: http://dx.doi.org/10.1111/j.1747-6593.1994.tb01157.x
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    Potential Impacts of Climatic Change and of Sea-Level Rise on the Yields of Aquifer, River and Reservoir Sources (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Using regional statistics of daily rainfall, a simple water-balance model was employed to generate runoff sequences with which to simulate the yield/storage behaviour of reservoirs in south-east England, in north-west England, and North Wales. Similarly sequences of recharge to an unconfined aquifer in eastern England were the basis of deriving its yield/storage behaviour. Then, taking scenarios of the year 2030 rainfall and evaporation, provided by the University of East Anglia's Climatic Research Unit, reductions in yield were calculated to be 5–15% below present-day values. For direct supply reservoirs, greater percentage reductions in yield were found to apply to the south-east region, as compared to the north-west. The results from the aquifer example are interpreted on a novel basis which allows an immediate comparison with the surface reservoir examples.Coastal sea-water intrusion was modelled for three common geological conditions (i) the Grimsby Chalk (confined), (ii) the Brighton Chalk (unconfined), and (hi) the Otter Valley Sandstone (unconfined). In all three cases the effect of a possible 0.6 m rise in mean sea level was shown to have only a marginal effect on sustainable yields, which reduced by about 1.5%.Estuarine fresh-salt water interfaces are important to the abstraction regime of freshwater intakes in the lower reaches of rivers. The effect of a 0.6-m sea-level rise on the saline interface location at high tide was evaluated by hydrodynamic computational models. Only a minor inland shin of the interface was found, less man 800 m in the Thames tideway and less than 500 m in the Lune estuary. The Severn estuary is exceptional in having its saline interface move 3.5 km landwards for the same 0.6-m rise in mean sea level.
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    Control of Hydrogen Sulphide by Air Injection into Rising Mains (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: During the long-distance pressure transportation of sewage, the interior of a rising main tends to become anaerobic, thereby producing a large amount of hydrogen sulphide at manholes and terminals. High concentrations of hydrogen sulphide have become a serious environmental and maintenance problem.In order to prevent the production of hydrogen sulphide in rising mains, the City of Kobe (in Japan) introduced a system to inject air directly into the main.This paper describes the results of studies on the effect of air injection on hydrogen sulphide inhibition and the relationship between water quality and the amount of air injected.
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    The Institution's View of the Proposed Revision of the Drinking Water Directive (80/778/EEC) (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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    IWEM Annual General Meeting (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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    Proceedings of IWEM Symposium on ‘Contaminated Land: From Liability to Asset’ (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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    URL: http://dx.doi.org/10.1111/j.1747-6593.1994.tb01129.x
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    Application of the ‘Biothane’ Wastewater Treatment System in the Soft Drinks Industry (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: This paper describes the experience gained by Yorkshire Water in the construction and operation of a wastewater treatment plant to deal with the effluent from Europe's largest canning and bottling factory (at Wakefield, West Yorkshire). The process which was chosen was the ‘Biothane’ upward-flow anaerobic sludge blanket system. Commissioning of the plant was fraught with difficulties due to the erratic organic load being discharged from the factory, along with larger than anticipated volumes of caustic solution.
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    The Management of Water Colour in Peatland Catchments (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: The problems of water-colour management in peatland catchments are discussed. Colour may be managed in three areas of the reservoir catchment system: on the catchment itself, in the channel/conduit system and within the reservoir. Whilst a number of workers have considered the management of catchment areas and some have evolved tributary turnout strategies, no previous research has considered the role of the reservoir in the amelioration or enhancement of water colour. The management of water colour at Thornton Moor catchment (near Bradford) is described. In this catchment a staged approach has been adopted, with colour being managed in an integrated manner at three stages along the catchment/conduit/reservoir system.
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    Book Reviews (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Books reviewed in this article: Water Wisdom, by Colin Allsebrook. Regional Ground-Water Quality. Edited by W. M. Alley. Respirometry of Activated Sludge, by Milenko Ros. Strategy for the Sustainable Use of England's Estuaries, by English Nature. European Environmental Law Casebook, by L. Krämer.
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    Benefits of Flow Data for Flood-Protection Design (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Stream gauging data play a vital role in the planning of flood mitigation strategies. A study of the value of stream flow data for the design of levee systems shows that the availability of a reasonable sample of pertinent data can be worth many times the cost of collecting that data.
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    The Institution's Response to the Government's Consultation Papers ‘Development Below Low Water Mark’ and ‘Managing the Coast’ (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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    Reconstruction of British Nuclear Fuel's Drigg Marine Outfall (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: In 1985 the House of Commons Environment Committee expressed reservations over some of the waste-management procedures followed by British Nuclear Fuels Ltd at their Drigg low-level radioactive waste disposal facility near Sellafield in Cumbria. These reservations prompted the company to implement a £20 million programme of improvements aimed at maximizing site usage, reducing trench leachate arisings and redirecting to the Irish Sea.This paper provides information and test results associated with design considerations and initial dilution testing, respectively, of a computercontrolled long sea outfall system designed to discharge leachate to the Irish Sea. Information is also provided on difficulties experienced during construction of the outfall.
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    Experience of Cast-Iron Mains Rehabilitation in the Gas Industry (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Since 1987 British Gas plc has undertaken an extensive programme of medium pressure (up to 2 bar) cast-iron mains replacement in urban locations, using a variety of rehabilitation techniques.This paper describes the experience of North Thames Region of British Gas plc, over the period 1987–1991, when the rehabilitation of over 230 km of mains was undertaken in the size range 300–460 mm.The techniques which were used favoured medium density polyethylene pipe wherever possible. However, about 100 km of rehabilitation was undertaken using hoselining, usually where mains were larger than 460 mm dia., or where aboveground access was restricted, or if the mains configuration included many changes of direction.This paper deals with (a) various aspects of operating rehabilitation contracts from a public utilities viewpoint, (b) the special factors relating to the inspection and testing of hoselined mains including factors found to contribute to failure, and (c) some of the controls that have been introduced to improve reliability of rehabilitation systems.
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    URL: http://dx.doi.org/10.1111/j.1747-6593.1994.tb00906.x
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    Use of Cement Kilns in Managing Solid and Hazardous Wastes: Implementation in Australia (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: The use of cement kilns for managing solid and hazardous wastes is facilitated by the high temperature, long gas retention periods, natural alkaline environment, minimum amount of waste produced and high thermal capacity. The main benefits include energy recovery, conservation of fossil fuels, reduction in cement production costs and the use of already existing facilities.The test burns conducted in cement kilns worldwide have demonstrated very high destruction efficiencies for most stable organic compounds, with toxic contaminants barely above the background levels.There are several cement plants in the US and Europe presently using solid and hazardous wastes as supplementary fuel. The application of this technology in Australia has been ignored in the past. An international conference (Kilnburn‘92) on the role of cement kilns in waste management was held recently in Australia and has enhanced the implementation of this technology in Australia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1747-6593.1994.tb00909.x
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    The Institution's Response to the Consultation Paper on ‘Proposed Amendments to the Water Resources Act 1991 and the Reservoirs Act 1975′ (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
    Details
    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1747-6593.1994.tb00916.x
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    The Institution's Response to the Consultation Paper on ‘River Quality: The Surface Waters (Fisheries Ecosystem) (Classification) Regulations 1993′ (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
    Details
    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1747-6593.1994.tb00915.x
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    WILLIAM OSWALD SKEAT, Bsc(Eng), MICE, FIMechE, (Hon Fellow) (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
    Details
    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1747-6593.1994.tb00918.x
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    The Institution's Response to the Consultation Paper on ‘Waste Management Paper No. 2/3: The Preparation of Waste Disposal (Management) Plans’ (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
    Details
    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1747-6593.1994.tb00917.x
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    Construction and Operation of a Submerged Aerated Filter Sewage-Treatment Works (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: The capacity of the sewage-treatment works at Silchester in Hampshire has been enhanced and the effluent quality improved to a high standard by the installation of a new submerged biological aerated filter plant. Ten prefabricated steel submerged aerated filters reduce BOD and fully nitrify settled domestic sewage from a population equivalent of 20 000.Comprehensive operating data are presented to demonstrate the ability of single-stage submerged downflow aerated biological filters to produce a nitrified effluent. The final effluent quality remains consistently within consent limits at 4.8 mg/l BOD, 7.0 mg/l SS and 0.5 mg/l NH3-N, all 95 percentiles. (Consent 7 mg/l BOD, 25 mg/l SS, and 5 mg/l NH3-N, 95 percentiles.)Data are presented on total coliform and E. Coli concentrations through the filter plant, showing better than 3 log reductions in the effluent.
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    Sustainability and the Water and Environmental Manager (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1747-6593.1994.tb01087.x
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    Treatment of Algal-Laden Water: Pilot-Plant Experiences (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
    Details
    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: In recent years an increase in the eutrophication of reservoirs has added to the problems of lowland surface-water treatment. A pilot plant was installed to test the effectiveness of various treatment regimes for a river source which was subject to occasional algal blooms, and a eutrophic reservoir source which was heavily contaminated with cyanobacteria (Oscillatoria sp.). The treatment processes adopted were dissolved-air flotation for chemical coagulation, sand and anthracite filtration, comparative disinfection stages using ozone and chlorine followed by granular activated carbon filtration.The dissolved-air flotation plant was not particularly effective for the removal of algae, but the sand/anthracite filtration process was capable of removing 50% of the algae. The ozone disinfection stage was adequate for disinfection and also reduced algal numbers. Overall the chlorine/granular activated carbon method did not perform as effectively as the ozone/granular activated carbon process; the iatter process was +99% effective for algai control, with river and reservoir sources.
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    Identification of Odour Problems in the River Dee: A Case Study (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
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    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: An intermittent strong vegetable/cabbage odour was noted on raw water abstracted from the River Dee (NW England). The source of the odour was traced to an industrial discharge from an animal feed manufacturer to a tributary of the River Dee. Analysis of water samples by CLSA GC-MS revealed the likely causes of the odour to be dimethyl disulphide and dimethyl trisulphide. 2-hydroxy-4-(methylthio)butanoic acid (HMB), a hydroxy methionine analogue growth supplement used by the feed manufacturer was a likely precursor to the odour problem. Studies conducted on the behaviour of HMB in untreated water showed it to be rapidly degraded. Degradation products included dimethyl disulphide, dimethyl trisulphide and methyl(methylthio)methyl disulphide. The odour of water samples incubated with HMB changed from that of potato to cabbage/sprout, indicating that breakdown of this compound was responsible for the vegetable odour on untreated river water.
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    Semiclassical surface-hopping approximations for the calculation of solvent-induced vibrational-relaxation rate constants (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 7520-7527 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Approximate schemes for the calculation of the rates of transitions between vibrational states of a molecule due to the interactions with a solvent are devised based on a rigorous, general semiclassical surface-hopping formalism developed earlier. The formal framework is based on an adiabatic separation of time scales between the fast molecular vibrations and the relatively slow bath motions. (The bath is composed of the solvent degrees of freedom plus all the molecular degrees of freedom other than vibrations.) As a result, the dynamics of the system are described in terms of bath motions occurring on adiabatic vibrational-energy surfaces, which are coupled by a nonadiabatic interaction. The time-dependent vibrational transition probability is evaluated by propagating the canonical density of the system, with the molecule in the initial adiabatic vibrational state, forward in time, and then projecting it onto the final adiabatic vibrational state of interest. The temporal evolution of the density is carried out with a semiclassical surface-hopping propagator, in which the motion of the bath on an adiabatic vibrational surface is described in terms of the familiar (adiabatic) semiclassical propagator, while transitions are accounted for in terms of instantaneous hops of the bath paths between the adiabatic vibrational surfaces involved, with an integration over all possible hopping points.Energy is conserved in the hops, and the only component of momentum that changes is the one along the nonadiabatic coupling vector. When the nonadiabatic interaction is taken into account to first order, the transition probability is predicted to become linear in the long-time limit. Various methods for extracting the relaxation rate constant in this limit are presented, and a simple model system with a one-dimensional bath is employed to compare their practical efficiency for finite time. In addition, this system is used to numerically demonstrate that local approximations for the adiabatic vibrational surfaces and the nonadiabatic coupling yield accurate results, with great reduction of the amount of computation time. Since a local approximation for the vibrational surfaces makes an N-dimensional problem separable into N effectively one-dimensional ones, this treatment is seen to be more generally applicable to realistic systems.
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    URL: http://dx.doi.org/10.1063/1.468245
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    Theoretical study of Ca(4s5p 1P)→Ca(4s5p 3P) energy transfer in collisions with He. Initial and final state alignment (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 7554-7565 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this paper we present the results of close-coupling calculations of the cross sections for Ca(4s5p 1P)→Ca(4s5p 3P) energy transfer in collisions with He, based on new potential energy curves. Particular attention is devoted to the simulation of the recent experiment of Smith and co-workers [J. Chem. Phys. 96, 8212 (1992)], in which, for the 1P→3P2 transfer both initial and final alignment are controlled with respect to the initial relative velocity vector of the two partners Vrel. The calculated polarization ratios (σ⊥/σ(parallel)), defined as the ratio of the cross sections for the 1P→3P transfer summed over final levels for initial alignment of the 5p orbital perpendicular and parallel to Vrel are in good agreement with the experimental results. The theoretical cross sections for the 1P→3P2 transfer determined in the so-called collision frame (σj1m1m1→j2m2m2), where the axis of quantization is taken along Vrel are in good agreement with the experiment in the case of initial perpendicular excitation, but show quantitative and qualitative disagreement in the case of initial parallel excitation. We find that relative populations into the final m2 levels depend strongly on the initial orientation of the 5p orbital with respect to the initial collision plane. However, we show, that in the case where the 5p orbital lies in the initial collision plane, the relative populations in the final m2 components of the 3P2 state depend exclusively on interactions among the exit channels.
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    URL: http://dx.doi.org/10.1063/1.468250
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    On the energy dependence of the steric effect in atom–molecule reactive scattering. I. A quasiclassical approach (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 7592-7602 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Experimental studies have shown that the steric effect in chemical reactions can decrease (e.g., for Ba+N2O→BaO*+N2) or increase [e.g., for Ca(1D2)+CH3F→CaF*+CH3] with increasing translational energy. Decreasing (negative) energy dependences have successfully been modeled with the angle dependent line of centers model. We present a classical model in which a positive energy dependence of the steric effect is explained by an isotropic, attractive long range potential. In this "trapping'' model we assume the reaction—apart from a cone of nonreaction at one side of the molecule—to be barrierless. This model shows that a positive energy dependence of the steric effect is not indicative of reorientation of the molecule, as has been suggested in the literature. Rather, the positive or negative energy dependence of the steric effect is shown to correlate with the absence or presence of a barrier to reaction and an attractive or repulsive long range potential. For the reorientation effects which occur in the case of anisotropic potentials, we consider the application of the standard quasiclassical trajectory (QCT) method and we introduce a modified QCT method. We argue that the latter is more suitable for the computation of the orientation dependent reactive cross section.
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    URL: http://dx.doi.org/10.1063/1.468253
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    Hydrated proton clusters and solvent effects on the proton transfer barrier: A density functional study (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 7633-7642 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The density functional calculations using the Perdew nonlocal corrections to exchange and correlation have been carried out for a sequence of hydrated proton clusters. The optimized structures were obtained up to H13O+6. It is found that H3O+ is indeed the central unit in all the lowest energy structures we found. Our results support the argument that the structure with a four-coordinate first solvation shell is very unlikely in small hydrated proton clusters. The density functional calculations with the Perdew nonlocal corrections to exchange and correlation give somewhat shorter hydrogen bond lengths, but slightly longer chemical bond lengths as compared with the post-Hartree–Fock calculations. The harmonic vibrational frequencies and IR intensities of various vibrational modes have been generated for all the structures optimized. Results for small clusters are compared with the high resolution experimental spectroscopy studies of Yeh et al. and Begemann et al. Results for larger clusters are used to interpret the low resolution spectra of Schwartz. Very good accord with experimental results is obtained. The solvent effects on proton transfer energy barriers in clusters have been studied by designing a few model systems. The barrier is found to be very sensitive to the solvent configurations. When the solvent water is replaced by the classical partial charge model, a significant change of the barrier is observed, indicating that a quantitative treatment will ultimately require a good pseudopotential to properly account for the quantum nature of the solvent. A combined density functional and molecular dynamics simulation was used to calculate the proton transfer energy and free energy barrier in aqueous solution. The barrier is found to be 3 kcal/mol higher than in gas phase. Very large solvent fluctuation is observed which may have a significant influence on the reaction rate.
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    Low-temperature proton transport in clathrates (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 7672-7682 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The impedance spectra are measured for protonated and deuterated clathrates, HClO4⋅5.5H2O and DClO4⋅5.5D2O, between 10 and 300 K. The conductance is investigated between 80 K and room temperature and the dielectric constant between 10 and 120 K. The data show deviation from the Arrhenius behavior of conductance in the low-temperature regime. A description of proton conductivity is developed on the basis of quantum theory of an elementary act of proton tunneling between donor–acceptor sites interacting with environmental fluctuations. Several models of the elementary act are considered. The mechanism, most consistent with the obtained data, incorporates—strong coupling of the proton with local vibrational modes of the closest environment and system diabatic transitions along these vibrational "coordinates''—fluctuations of the tunneling barrier for the proton. At low temperatures the motion along the vibrational coordinates is no longer purely classical and the slow mode tunneling takes place. The latter gives rise to a curvature in the Arrhenius plots apprehended as a decrease of the apparent activation energy at lower temperatures. The observed isotope effect is in line with the lower deuteron tunneling probability due to doubling the mass, though other parameters may also be affected by deuteration.
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    Optical potential coupled to discrete variable representation for calculations of quasibound states: Application to the CO(B 1Σ+–D'1 Σ+) predissociating interaction (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 7580-7591 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The optical potential method initially proposed by Jolicard and Austin in the context of the stabilization method is reviewed here and used with the accurate and the efficient discrete variable representation method to obtain the energies and the widths (respectively, the real and the imaginary part of the resonance energies) of rovibrational predissociated states of diatomic molecules. In this method the resonances for an n coupled states problem are obtained by a direct diagonalization of the Hamiltonian matrix in the diabatic representation. This Hamiltonian matrix is directly evaluated in the discrete variable representation using the Fourier grid Hamiltonian method proposed by Marston and Balint-Kurti. In this approach, two optical potentials are tested and used here to impose the asymptotic behaviors of the boundary conditions which are compatible with the resonance states. The method is exemplified for the B 1Σ+–D'1 Σ+ Rydberg–valence predissociating interaction in the CO molecule.
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    A self-adaptive multilevel finite element method for the stationary Schrödinger equation in three space dimensions (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 7643-7650 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: An error controlled finite element method (FEM) for solving stationary Schrödinger equations in three space dimensions is proposed. The method is based on an adaptive space discretization into tetrahedra and local polynomial basis functions of order p=1–5 defined on these tetrahedra. According to a local error estimator, the triangulation is automatically adapted to the solution. Numerical results for standard problems appearing in vibrational motion and molecular structure calculations are presented and discussed. Relative precisions better than 1e-8 are obtained. For equilateral H++3, the adaptive FEM turns out to be superior to global basis set expansions in the literature. Our precise FEM results exclude in a definite manner the stability or metastability of equilateral H++3 in its ground state.
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    Pressure dependence of magnetic coupling in ionic solids from ab initio cluster model calculations (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 7683-7685 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The dependence of the magnetic coupling constant, J, with the pressure has been studied by an ab initio cluster model approach in a typical ionic solid such as KNiF3. By computing J at different values of the lattice parameter R, we predict a power law of the form ||J||≈R−n with 10.5〈n〈13.3 in good agreement with the suggested experimental value. This behavior is found even for the simplest Ni2F cluster model described by a complete active space configuration interaction wave function in which the active orbitals correspond to the open shell of each Ni2+ cation.
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    Calculation of rovibronic structures in the lowest nine excited 1Σ+g+1Πg+1Δg states of H2, D2, and T2 (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 7692-7706 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have calculated the rovibronic structures which arise from the simultaneous radial and angular couplings among the lowest nine excited 1Σ+g, 1Πg, and 1Δg states in H2, D2, and T2. Using ab initio potential curves, adiabatic corrections, and nonadiabatic coupling functions wherever possible, we have solved the coupled vibronic equations for all bound states below the 1s+2l dissociation limit up to J=5 in H2 and D2, and up to J=7 in T2. The good agreement of the bulk of the data with spectroscopic results enables us to eliminate spurious assignments in old spectroscopic work (e.g., all old assignments involving the 4s O 1Σ+g state are spurious), and to make numerous new assignments. We present updated tables of spectroscopic term values for H2 and D2. The absolute energy errors of the ab initio Born–Oppenheimer energies around the minima of the potential curves appear to be at most of the order of the radiative energy corrections ((approximately-equal-to)0.1 cm−1) in the states 1σg2sσg E and (1σu)2 F, less than 1 cm−1 in the states 3dσ G, 3s H, and 3dπ I, less than 2 cm−1 in the 4s O state, and approximately 4 cm−1 in the 4dσ P state.
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    Computer simulations of cesium–water clusters: Do ion–water clusters form gas-phase clathrates? (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 7873-7881 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The structure and energetics of cesium ion–water clusters have been investigated using classical molecular dynamics computer simulations and a polarizable interaction model. Recent experiments by Selinger and Castleman [J. Phys. Chem. 95, 8442 (1991)] indicate that the mass-spectral distributions for these clusters exhibit "magic number'' oscillations at temperatures below approximately 160 K. The observed behavior of this and related charged clusters is commonly attributed to the formation of clathratelike cage structures around a central ionic species. The relationship between the structural and energetic properties of cesium ion–water clusters is reported here as a function of temperature for clusters with between 18 and 22 water molecules. The clusters exhibit solidlike dynamical behavior at kinetic temperatures below about 170 K, and liquidlike behavior at higher temperatures. A thorough analysis of energy minimized (0 K) structures indicates that the most stable clusters consist of water cages surrounding the cesium ion. These cages are related to the proposed clathratelike structures but contain additional 4- and 6-membered water rings and fewer 5-membered rings. The calculated global energy minima exhibit an energetic alternation with cluster size that is consistent with the experimentally observed mass-spectral distributions. In contrast, in the liquidlike regime there are only minor variations in calculated structural and dynamical properties as a function of cluster size. In addition, there is no statistically significant size dependence for the cluster binding energies in the liquidlike regime that might be correlated with experimental data. These results suggest that magic number stability in ion–water clusters may occur only at "low'' energies in the solidlike cluster regime.
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    Multibody distribution function contributions to the heat capacity for the truncated Lennard-Jones fluid (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 7934-7938 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have performed a series of standard NVT Monte Carlo simulations in which we have calculated the configurational heat capacity, Cv, of a truncated Lennard-Jones model fluid by the fluctuation theorem. As we found in a previous investigation, the heat capacity exhibited two extrema as a function of density on sufficiently low temperature isotherms. During the course of these runs, we have decomposed the heat capacity into the sum of quantities, Cv(2), Cv(3), and Cv(4), which are averages over two, three, and four body distribution functions. We analyze combinations of the three contributions to gain insight into the nature of the extrema. In particular, we find that the sum Cv(2)+Cv(3) has a maximum and a minimum at all temperatures studied. The magnitude and slope of Cv(2)+Cv(3) compared with Cv(4) determines whether or not Cv itself has maxima and minima.
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    Water near a planar interface: Atom-based integral equation theory (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 7925-7933 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The structure and properties of an atom-based model of water next to a planar interface are solved using an approximate integral equation theory. The input to the calculations is the structure of the bulk water in the form of the direct correlation functions. Predictions from the theory include the oxygen and hydrogen density profiles perpendicular to the interface, the mean electrostatic potential, the potential of zero charge, and the differential capacitance. The predicted structure is relatively insensitive to both the surface potential and the details of the short-range wall–water potentials, and exhibits a layered structure which extends approximately 15 A(ring) into the liquid. For our initial choice of the short-range wall–water potential, we predict a value of −32 mV for the potential of zero charge and a differential capacitance of 4.89 μF cm−2 for pure water at a planar interface. The capacitance is apparently independent of the surface charge density and the surface potential.
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    Near ultraviolet photolysis of methanethiol studied by H atom photofragment translational spectroscopy (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 7538-7547 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The technique of H Rydberg atom photofragment translational spectroscopy has been applied to a high resolution study of the primary photochemistry of methanethiol (CH3SH) following excitation at a wide range of wavelengths in the near ultraviolet. In accord with previous studies of this molecule, excitation within its first (1 1A‘−X˜ 1A') absorption continuum is shown to result in S–H bond fission. Spectral analysis yields a refined value for the bond dissociation energy: D00(CH3S–H)=30 250±100 cm−1. The resulting CH3S(X˜) fragments are deduced to carry only modest vibrational excitation, distributed specifically in the ν3 (C–S stretching) mode and in one other mode having a wave number of ∼1040 cm−1. We associate this latter mode with bending of the CH3 moiety in the plane containing the C and S nuclei and the lobe of the unpaired electron which was originally involved in the S–H bond. Decreasing the excitation wavelength (while remaining within the first absorption continuum) results in an increase in both the vibrational and rotational excitation of the CH3S(X˜) fragments, but a decrease in the relative yield of the upper (2E1/2) spin–orbit component. Excitation at still shorter excitation wavelengths accesses the second (2 1A‘−X˜ 1A') absorption band of CH3SH. The CH3S fragments resulting from S–H bond fission at these excitation wavelengths are observed to carry very much higher levels of vibrational excitation in the above two modes. The observation of H atoms attributable to secondary photolysis of SH(X) fragments indicates increased competition from the alternative C–S bond fission channel at these shorter excitation wavelengths. Additional peaks in the H atom time-of-flight spectrum, most clearly evident following excitation at wavelengths in the range 213–220 nm, are interpretable in terms of secondary photolysis of the primary CH3S(X˜) fragments yielding thioformaldehyde (H2CS), primarily in its A˜ 1A2 excited electronic state. Symmetry arguments provide an explanation for this specific electronic branching in the near ultraviolet photolysis of CH3S fragments.
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    Formation of striped surface phases by short-range forces (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 8082-8086 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Anisotropic Cu–O islands form striped periodic supergratings upon annealing an oxygen-exposed Cu(110) surface. While the formation of these striped phases has been attributed to long-range repulsive forces between stripes, we show using the one-dimensional lattice gas model and Monte Carlo simulations that short range adsorbate–adsorbate interactions are capable of producing striped phases.
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    URL: http://dx.doi.org/10.1063/1.468453
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    The microwave spectrum, structure, and large amplitude motions of the methylacetylene⋅SO2 complex (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6512-6522 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Rotational spectra of five isotopomers of the methylacetylene⋅SO2 (MA⋅SO2) van der Waals complex have been observed with a Fourier transform microwave spectrometer. Each species showed two sets of rotational transitions, one associated with the A (m=0) and the other with the E (m=±1) methyl group internal rotation states. The rotational transitions of the isotopomers with S 16O2 and the doubly substituted S 18O2 also showed inversion splitting ranging from tens of kHz to a few MHz. This splitting was absent in the S 16O 18O isotopomers. The spectra of these species have been assigned and fit, yielding rotational constants, which allowed a complete determination of the structure of the complex. The SO2 was found to sit above the carbon–carbon triple bond, with one of the S–O bonds roughly parallel to the symmetry axis of methylacetylene. The centers-of-mass distance between the two monomers was determined to be 3.382(10) A(ring). The center frequencies of the inversion doublets (or quartets) were used in a fit of both the A and the E transitions; the barrier hindering the internal rotation of the methyl group was determined to be 62.8(5) cm−1. Based on the dependence of the inversion splitting on the transition dipole direction and isotopic substitution, the inversion motion was identified as an "in plane'' wagging of the SO2 relative to methylacetylene. A pure inversion splitting of 3.11 MHz (free from rotation) was extracted from the A-state spectrum of the normal species, from which an inversion barrier height of about 63 cm−1 was estimated.
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    Electronically excited states in size selected solvated alkali metal atoms. I. First observation in NaNH3 by resonant two color two photon ionization (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6559-6564 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Resonant two color two photon ionization is used to investigate the first electronically excited state of NaNH3 as a first example of size selected, solvated alkali metal atoms systems (alkali⋅solventn). The observed spectrum shows a complex vibrational and rotational structure. The 0-0 transition is found at 12 220 cm−1 (1.52 eV), in good agreement with recent theoretical calculations. With increasing laser power ionic fragments of the molecule are seen, indicating possible new avenues to study the dynamics of charge transfer processes in this type of model system.
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    Differences between L3 and L2 x-ray absorption spectra of transition metal compounds (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6570-6576 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The differences between L3 and L2 edges of 3d and 4d transition metal complexes and compounds in octahedral symmetry are discussed. The main origin of these differences are the multiplet effects due to the coupling of the 2p core wave function and the 3d and 4d valence wave functions. The 3d and 4d spin–orbit coupling is a second origin of difference. For 3d systems the multiplet effects dominate all other interactions and the L3 and L2 edge are completely mixed and reordered. For 4d systems the core hole spin–orbit coupling is large and the L3 and L2 are separated by about 100 eV with a ratio close to 2:1. The differences between the L3 and L2 edge originate from the weight transfer between the t2g and eg peaks due to the multiplet effect. This weight transfer is about 25% for the L3 edge and about 5% for the L2 edge, which implies that for a comparison to single-particle calculations the L2 edge is preferable to use. Partly filled 4d systems are low-spin and the occupation of the t2g states implies a decrease of the first peak. This decrease is stronger for the L2 edge, implying an increase in the L3:L2 ratio. For 4d5 systems transitions to the t2g hole are only possible at the L3 edge due to the combined effects of 4d spin–orbit coupling and the dd multiplet effects.
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    Calculation of internal conversion rate constants of single vibronic levels in S1 benzene (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6632-6639 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In the present work, a direct count procedure designed for the assessment of the decay rates of nonradiative processes in polyatomic molecules has been introduced. Using the described approach the internal conversion (IC) decay rates of a considerable number of single vibronic levels (SVL) in S1 benzene have been estimated. The decay rates of "bright'' SVLs were found to increase only slowly, while those of "dark,'' out-of-plane modes containing states grew far more rapidly with the excess vibrational energy Ev in S1. The observed behavior with Ev as well as the absolute magnitude of the calculated IC decay rates were in general conformity with the existing experimental evidence.
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    Measuring the structure of etched silicon surfaces with Raman spectroscopy (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 8055-8072 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have measured the unenhanced, nonresonant surface Raman spectra of one monolayer of hydrogen bound to flat and stepped Si(111) surfaces prepared using a novel, aqueous fluorine etch. The orientation and normal mode composition of adsorbate vibrations are obtained from polarized, angle-resolved Raman spectra using a 3-layer dielectric model. This approach requires the experimental determination of both the anisotropy in the dynamic polarizability of the adsorbate bond and the effective dielectric constant in the vicinity of the adsorbate. The measured Si–H bond anisotropy is 0.263±0.028 in good agreement with gas phase measurements. The adsorbate dielectric constant is measured to be 3.78±0.20; this response is clearly nonlocal and predominantly due to polarization of the underlying silicon lattice. Using this technique, we find that the step dihydride on a Si[6(111)-(1¯1¯2)] surface is rotated 37°±4° from the surface normal in good agreement with the 31° predicted by ab initio cluster techniques, but significantly larger than the 12.5° predicted by pseudopotential slab calculations. In contrast to both theoretical predictions, the normal modes of this step dihydride display little concerted motion indicating that subsurface relaxation near the step edge reduces steric interactions much further than predicted. The observed anisotropic etch rates, evidenced by the production of atomically straight steps, are explained in terms of the measured distortion at the step edge.
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    Stabilized hydrogen on Cs-modified Al(111): Evidence for formation of alkali aluminum dihydride surface complex (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 8087-8093 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The adsorption of hydrogen on Cs-modified Al(111) surfaces has been studied using high-resolution electron energy loss spectroscopy (HREELS) and temperature programmed desorption (TPD). A stabilized hydrogen species which desorbs simultaneously with Cs at 480 K (γ hydrogen) appears in the presence of Cs and the ratio between the number of Cs and that of the γ hydrogen is 1:2, independent of Cs coverage, which is indicative of a substantial attractive interaction between Cs and the γ hydrogen. HREEL spectra of the γ hydrogen exhibit intense loss peaks at around 800 and 1700 cm−1. Detailed analyses of these loss peaks using isotope mixtures (H+D) indicate that the γ hydrogen is directly bound to Al with a geminal structure (AlH2). From the combined results of TPD and HREELS, it is considered that a cesium aluminum dihydride complex (CsAlH2) is formed on the surface, which is supported by ab initio calculations.
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    Highly excited hydrogen molecules desorbed from a surface: Experimental results (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 8152-8158 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rovibrational excitation of hydrogen molecules resulting from recombination of atoms on a metallic surface has been observed by means of an electronic collision method. We present the obtained H− experimental spectra reflecting the vibrational populations of the desorbed hydrogen molecules. This study brings to light the fundamental role of the nature of the metallic surface in the recombination process: excitation of higher vibrational levels (from v=5 to v=8) is observed only on those metal surfaces which strongly chemisorb atomic hydrogen. To explain these observations we propose the formation, on these surfaces, of a physisorbed H layer on the chemisorbed one.
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    General equations for describing temperature-programmed surface segregation (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 8200-8204 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Temperature-programmed segregation on the surface and diffusion from the surface into the bulk are shown to be described by an integral equation. This equation is integrated by taking into account that the diffusion coefficient rapidly increases with increasing temperature. The results obtained are used to study the effect of saturation and adsorbate–adsorbate interactions on the transient kinetics with two types of the initial conditions. In the first case, the surface and bulk are in equilibrium in the beginning, and then the surface coverage decreases with increasing temperature due to diffusion from the surface into the bulk. The second class of kinetics corresponds to the situation when in the beginning the surface coverage is much lower than the equilibrium one. In the latter case, the surface coverage first increases with increasing temperature due to segregation on the surface, then reaches maximum, and finally again becomes low.
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    Laser-induced fluorescence detection of ClO radicals at 167–180 nm (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 8262-8263 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: ClO radicals are detected by a laser-induced fluorescence technique, using the C 2Σ–X 2Π transition with a tunable vacuum ultraviolet laser system. Predissociation in the C 2Σ state is discussed in terms of the fluorescence lifetime and excitation spectra. The vibrational distribution of ClO produced by the reaction between O(1D) and HCl is measured.
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    Study of the ArBr−, ArI−, and KrI− anions and the corresponding neutral van der Waals complexes by anion zero electron kinetic energy spectroscopy (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6538-6551 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Three rare gas halide (RgX−) anions, ArBr−, ArI−, and KrI−, and the corresponding open-shell van der Waals complexes, ArBr, ArI, and KrI, were studied with anion zero electron kinetic energy (ZEKE) spectroscopy. Photodetachment of each anion accesses the three lowest-lying electronic states (the X1/2, I3/2, and II1/2 states) of the neutral complex. The spectra for each system reveal well-resolved progressions in the low frequency vibrations of the anion and the three neutral electronic states, providing a detailed spectroscopic probe of the Rg⋅X− and Rg⋅X interaction potentials. The line shapes observed in the ZEKE spectra are analyzed in terms of the line strengths of the underlying rotational transitions. From our data, we construct the potential energy curve for each neutral state as well as for the anion, and these interaction potentials are compared to potentials obtained from scattering and ion mobility experiments.
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    Control of a quantum dynamics by a locally optimized laser field. II. Application to a system with dissipation (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6586-6592 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present a theory for controlling the dynamics of a dissipative, quantum system with a laser field optimized locally in time. The theory is applicable to both weak and strong field control of the quantum dynamics. The theoretical groundwork is based on the equation of motion of the density matrix in Liouville space. Interactions between the molecules and the heat bath are taken into account within a Markov approximation. The derivation of the locally optimized laser field in a feedback form is based on the local optimization theory in the Hilbert space, proposed in a previous paper [M. Sugawara and Y. Fujimura, J. Chem. Phys. 100, 5646 (1994)]. The theory is applied to a simple, two-level quantum system with a dephasing constant. We present both the calculated time evolution of the off-diagonal density matrix element and that of the population of the states in the optimized laser field. These calculations show that the control of the system by the laser field is sufficient to avoid the dephasing effects. We discuss how the dephasing dynamics affects the optimization of the laser field.
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    Dissociation dynamics of Ar+n (n=3–16) in collision with He and Ne (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6625-6631 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Dissociation dynamics of Ar cluster ions, Ar+n (n=3–16), in collision with He and Ne atoms was investigated by measuring the absolute dissociation cross sections and the branching fractions of the product ions at the collision energies of 0.1–10 eV in the center-of-mass frame. The cross sections and the branching fractions were successfully explained in terms of collisional excitation of the parent cluster ion and subsequent dissociation of it; the collisional excitation was treated by a hard sphere collision model with the aid of the molecular dynamics (MD) and the diatomics-in-molecules (DIM) calculations reported previously, and the subsequent dissociation was explained by the Rice–Ramsperger–Kassel (RRK) theory.
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    The thermal conductivity of argon in the critical region (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6944-6963 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have measured the thermal conductivity of argon at temperatures from 302 K down to 150.8 K and at densities up to 25 mol L−1. The data were obtained with a steady-state method and we employed a guarded parallel-plate apparatus designed especially for investigating the thermal conductivity of fluids in the critical region. To interpret the data in the critical region a scaled crossover equation of state for argon in the critical region has been constructed. Equations for the thermal conductivity and viscosity of argon as a function of density and temperature are presented.
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    Real time path integral methods for a system coupled to an anharmonic bath (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6708-6716 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We propose an efficient path integral scheme for calculating the quantum dynamics of an arbitrary one-dimensional system coupled nonlinearly to many anharmonic noninteracting "bath'' degrees of freedom. The starting point is an improved discretization of the path integral in terms of numerically constructed propagators [Chem. Phys. Lett. 193, 435 (1992)]. The resulting influence functional is comprised of one-dimensional correlation functions with step-structured time-dependent potentials and therefore is similar in structure to that employed in the spin-boson calculations of Coalson [J. Chem. Phys. 86, 995 (1987)]. In the present case, though, the influence functional is nonlinear and is computed using numerical iterative wave function propagation methods. Numerical tests on a system coupled to ten anharmonic oscillators demonstrate the efficiency of the proposed scheme, which requires numerical effort that scales only linearly with the number of anharmonic bath degrees of freedom.
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    Auger electron–ion coincidence experiment on nitrogen molecule excited by electron impact (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6565-6569 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The first Auger electron–ion coincidence experiment on the nitrogen molecule excited by electron impact is described. The kinetic energy releases of the N++ and the N+ fragments in the 43–72 eV binding energy range have been measured. The experimental results are compared with previous experimental data obtained by using synchrotron radiation and theoretical predictions.
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    Derivation and efficient implementation of the fast multipole method (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6593-6605 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The fast multipole method (FMM) of Greengard evaluates Coulomb interactions of point charges with computational requirements that increase linearly with the number of particles. In this work, the central transformations of the FMM are obtained in a very compact manner from simple algebraic manipulations of two addition theorems. The intermediate multipole and Taylor expansions are defined differently from previous work to yield simplified and more efficient transformations. Error estimates are obtained due to the effect of multipole truncation and the use of the multipole to Taylor transformation operator. Efficient implementation of the FMM for potential and forces is discussed, and calculations are presented that probe the accuracy and performance of the method.
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    Ring opening reaction dynamics in the reaction of hydrogen atoms with ethylene oxide (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6615-6624 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Ethylene oxide, C2H4O, is a three-membered ring with a single oxygen atom bridging the two carbons. Reactions of H and D atoms with ethylene oxide have been studied in the gas phase to provide insight into the dynamics of three-membered ring opening. H atoms were produced by photolyzing HI in the wavelength range 240–266 nm. The channel leading to OH+C2H4 was monitored via laser-induced fluorescence (LIF) of the OH A 2Σ←X 2Π system. The D atom reaction yields OD with no hydrogen scrambling. With an available energy of 23 000 cm−1, the average OH D rotational energy is ∼350 cm−1 for OH(v=0) and OD(v=0) and ∼250 cm−1 for OD(v=1). OH(v=1) was not observed, while the OD(v=1) population was about one-tenth that of OD(v=0). There was no apparent bias in populations between Λ doublets in each of the spin–orbit states for both OH and OD. Doppler broadening of OH(v=0) rotational lines was measured to evaluate the average center-of-mass (c.m.) translational energy, which was found to be ∼2300 cm−1. On average, the ring opening process deposits ∼10% of the available energy into c.m. translation, ∼2% into OH rotation, and ∼88% into ethylene internal energy. Comparison with CH2CH2OH unimolecular dissociation dynamics and theoretical transition state calculations leads to a likely mechanism in which hydrogen abstracts oxygen via sequential C–O bond fission without involving a long-lived CH2CH2OH intermediate.
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    Cluster experiments in radio frequency Paul traps: Collisional relaxation and dissociation (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6666-6685 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: This paper presents techniques to store, manipulate, and detect cluster ions in an rf Paul trap as an approach to study the physics and chemical physics of clusters. The trap has been designed to be the primary experimental environment in the sense that experimental manipulation and ion detection are performed in situ within the trap. Specific design considerations for the trap and rf electronics relevant to metal cluster experiments are discussed. We present the application of these techniques to measurements of trapped C+60 in order to estimate their limitations for studying metal cluster ions. This paper demonstrates the capability to nondestructively detect small variations in the number of trapped C+60 ions with an ion noise level of ≈100 ions limited by thermal current fluctuations. Trapped ion lifetimes of τion(approximately-greater-than)30 min are measured following the relaxation of C+60 translational energy to ≈300 K. Measurements of the collisional dissociation of trapped C+60 ions at rates 〈100 s−1 by He at ∼10−6 Torr have been performed and the products detected in situ by the mass distribution of the C+n products. Several possibilities for metal cluster experiments in rf Paul traps are discussed.
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    The role of adsorbate–adsorbate interactions in the rate oscillations in catalytic CO oxidation on Pd (110) (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6717-6727 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The CO+O2 reaction on Pd(110) exhibits kinetic oscillations above pO2 ≈ 10−3 Torr and bistability below this pressure. Based on the reversible formation of subsurface oxygen and the Langmuir Hinshelwood mechanism of catalytic CO oxidation, a mathematical model had been developed which described the occurrence of rate oscillations and most of the qualitative features of the oscillations. This model, however, failed to reproduce the change from bistability to oscillatory behaviour with increasing pO2. In this paper we demonstrate that by introducing repulsive interactions between COad and Oad, the subsurface oxygen model correctly reproduces the experimentally determined stability diagram in pO2,pCO parameter space. The effect of the repulsive interactions is to reduce the activation barrier for penetration of chemisorbed oxygen into the subsurface region, thus facilitating the formation of subsurface oxygen at high coverages. For the improved subsurface oxygen model a bifurcation analysis has been conducted in pO2,pCO parameter space. The influence of the constants in the model has been analyzed likewise with bifurcation theory.
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    Photodetachment in the gaseous, liquid, and solid states of matter (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6728-6742 
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    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have made absolute cross section measurements of laser photodetachment of C6F−6 ions embedded in gaseous tetramethylsilane (TMS) and compared the results at low gas densities with measurements in nonpolar liquids and solids. The measurements indicate that the photodetachment cross section of C6F−6 in gaseous TMS is about three times larger than in liquid TMS. This is rationalized by considering the effect of the medium on both the photoabsorption and the autodetachment processes. The photodetachment cross section in both the gas and the liquid exhibits (at least) two maxima due to autodetaching negative ion states. It is argued that these are due to σ*→σ* transitions in C6F−6. The relative positions of these "superexcited'' anionic states did not change appreciably in going from the gas to the liquid and the solid, indicating similar influences of the medium on them. As expected, the photodetachment threshold in the condensed phase is shifted to higher energies compared to the gaseous phase. This shift is consistent with recent photoelectron studies of photodetachment of C6F−6 clusters. The present study clearly shows that the photodetachment from negative ions embedded in all states of matter proceeds directly or indirectly via negative ion autodetaching states, and that for nonpolar media, the effect of the medium can be accounted for by considering the macroscopic properties of the medium described by its dielectric constant ε and refractive index n.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.468365
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  • 95
    Electronic Resource
    Electronic Resource
    Molecular dynamics simulation of ionic mobility. I. Alkali metal cations in water at 25 °C (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6964-6974 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We describe a series of molecular dynamics simulations performed on model cation-water systems at 25 °C representing the behavior of Li+, Na+, K+, Rb+, and Cs+ in an electric field of 1.0 V/nm and in its absence. The TIP4P model was used for water and TIPS potentials were adapted for the ion-water interactions. The structure of the surrounding water molecules around the cations was found to be independent of the applied electric field. Some of the dynamic properties, such as the velocity and force autocorrelation functions of the cations, are also field independent. However, the mean-square displacements of the cations, their average drift velocities, and the distances traveled by them are field dependent. The mobilities of the cations calculated directly from the drift velocity or the distance traveled by the ion are in good agreement with each other and they are in satisfactory agreement with the mobilities determined from the mean-square displacement and the velocity autocorrelation function in the absence of the field. They also show the same trends with ionic radii that are observed experimentally; the magnitudes are, however, smaller than the experimental values in real water by almost a factor of 2. It is found that the water molecules in the first solvation shell around the small Li+ ion are stuck to the ion and move with it as an entity for about 190 ps, while the water molecules around the Na+ ion remain for 35 ps, and those around the large cations stay for 8–11 ps before significant exchange with the surroundings occurs. The picture emerging from this analysis is that of a solvated cation whose mobility is determined by its size as well as the static and dynamic properties of its solvation sheath and the surrounding water. The classical solventberg model describes the mobility of Li+ ions in water adequately but not those of the other ions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.468323
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  • 96
    Electronic Resource
    Electronic Resource
    Molecular dynamics simulations of a flexible molecule in a liquid crystalline solvent (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 7027-7036 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Molecular dynamics simulations of a hexane molecule in isotropic, nematic, and smectic phases are reported. The interactions between the solvent molecules is modeled using the Gay–Berne potential and the hexane–solvent potential is modeled as an explicit site–site interaction. The conformational distributions are reported of the hexane molecule at a fixed temperature but at different densities in isotropic, nematic, and smectic phases, and these are compared with the results from Monte Carlo simulations on an isolated molecule at the same temperature. The positions and orientations of the hexane molecule at each time step in the molecular dynamics simulations are used to calculate interproton dipolar coupling constants. These data are used to test the mean field models which have been applied with dipolar couplings obtained previously from nuclear magnetic resonance (NMR) experiments to yield conformational distributions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.468328
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  • 97
    Electronic Resource
    Electronic Resource
    Stratification-induced order–disorder phase transitions in molecularly thin confined films (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6865-6873 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: By means of grand canonical ensemble Monte Carlo simulations of a monatomic film confined between unstructured (i.e., molecularly smooth) rigidly fixed solid surfaces (i.e., walls), we investigate the mechanism of molecular stratification, i.e., the tendency of atoms to arrange themselves in layers parallel with the walls. Stratification is accompanied by a heretofore unnoticed order–disorder phase transition manifested as a maximum in density fluctuations at the transition point. The transition involves phases with different transverse packing characteristics, although the number of layers accommodated between the walls remains unchanged during the transition, which occurs periodically as the film thickens. However, with increasing thickness, an increasingly smaller proportion of the film is structurally affected by the transition. Thus, the associated maximum in density fluctuations diminishes rapidly with film thickness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.468316
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  • 98
    Electronic Resource
    Electronic Resource
    Aqueous solvation dynamics with a quantum mechanical Solute: Computer simulation studies of the photoexcited hydrated electron (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6902-6916 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have used molecular dynamics simulation to explore aqueous solvation dynamics with a realistic quantum mechanical solute, the hydrated electron. The simulations take full account of the quantum charge distribution of the solute coupled to the dielectric and mechanical response of the solvent, providing a molecular-level description of the response of the quantum eigenstates following photoexcitation. The solvent response function is found to be characterized by a 25 fs Gaussian inertial component (40%) and a 250 fs exponential decay (60%). Despite the high sensitivity of the electronic eigenstates to solvent fluctuations and the enormous fractional Stokes' shift following photoexcitation, the solvent response is found to fall within the linear regime. The relaxation of the quantum energy gap due to solvation is shown to play a direct role in the nonradiative decay dynamics of the excited state electron, as well as in the differing relaxation physics observed between electron photoinjection and transient hole-burning (photoexcitation) experiments. A microscopic examination of the solvation response finds that low frequency translational motions of the solvent play an important role in both the inertial and diffusive portions of the relaxation. Much of the local change in solvation structure is associated with a significant change in size and shape of the electron upon excitation. These results are compared in detail both to previous studies of aqueous solvation dynamics and to ultrafast transient spectroscopic work on the hydrated electron.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.468319
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  • 99
    Electronic Resource
    Electronic Resource
    The direct correlation functions and bridge functions for hard spheres near a large hard sphere (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6975-6978 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The recent Monte Carlo data of Degrève and Henderson for the density profiles of hard spheres near a large hard sphere are used to obtain direct correlation functions and bridge functions for this system both directly, using the Ornstein–Zernike relation and an approximation, due to Verlet, for the bridge function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.468324
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  • 100
    Electronic Resource
    Electronic Resource
    Density-functional modeling of structure and forces in thin micellar liquid films (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6979-6991 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Recent equilibrium force measurements on aqueous films of surfactant above the critical micelle concentration show oscillations for film thicknesses up to 50 nm. To model this phenomenon we express the micellar contribution to the disjoining pressure in terms of thickness-dependent inhomogeneous micelle number density distributions through the film. Density functional theory is used to calculate micelle density profiles, presuming the micelles to behave as charged spheres interacting with each other, and with the film interfaces, through screened-Coulomb potentials. The background electrolyte permits dilute micellar solutions to act as concentrated systems exhibiting pronounced layering in the film. For a 0.1 M sodium dodecylsulfate (SDS) film we find up to five micellar layers for a film thickness equal to ten micelle diameters (d), the layer separation scaling with the effective diameter (deff/d=1.86) which includes the micelle Debye atmosphere. The peaks are largest near the interfaces and decay toward the bulk density at the film midplane. The corresponding disjoining pressures show oscillations with the same distance scaling between the branches as in the density profiles; these values are consistent with experiment. With decreasing film thickness, the (meta-)stable disjoining pressure regions represent micellar layers in the film being forced closer together, raising the pressure until the interior layer is expelled, allowing more space between the remaining micellar layers at that thickness.Repulsive (positive) disjoining pressures result from layer separations less than the corresponding bulk value whereas attractive (negative) regions represent more distance between layers than that in the bulk. The 0.2 M SDS disjoining pressure isotherm exhibits one additional layer than the 0.1 M case for thicknesses up to 50 nm. The pressure magnitudes of the former case are about twice that of the latter. Addition of ionic salts greatly inhibits the long-range micellar structuring. For SDS foam films, predicted disjoining pressures are much higher than measured values. Comparison with cetyltrimethyl-ammonium bromide (CTAB) micellar films in the surface forces apparatus, however, shows near quantitative agreement. The nature of the confining interfaces thus plays a key role in supporting the internal micellar structuring.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.468325
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