bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Teacher-Encouraged Physical Activity on Preschool Playgrounds
Authors: Brown William H. , Googe Heather Smith , McIver Kerry L. , Rathel Jeanna Marie
Published: March 2009

Increased numbers of young children who are overweight have become a significant health problem in the United States. Public health investigators have hypothesized that increased caloric intake and low levels of physical activity may be associated with the troubling trend of weight problems among children. To enhance preschool children's moderate to vigorous physical activity on playgrounds the authors develop, implement, and evaluate two practical teacher-implemented activities. Direct observations of five children in two preschool programs during teacher-implemented activities indicate increased moderate to vigorous physical activity on intervention days relative to nonintervention days (i.e., business-as-usual conditions). The results and implications for preschool practitioners are discussed.
Intervention With African American Premature Infants
Authors: Teti Douglas M. , Black Maureen M. , Viscardi Rose , Glass Penny , O'Connell Melissa A. , Baker Linda , Cusson Regina , Reiner Hess Christine
Published: March 2009

This study evaluates the efficacy of an early intervention program targeting African American mothers and their premature, low birth weight infants at 3 to 4 months' corrected age from four neonatal intensive care units, 173 families are recruited (84 intervention, 89 control). The 8-session, 20-week intervention consists of a psychoeducational video, serial administrations of the Brazelton Neonatal Behavioral Assessment Scale, and maternally administered infant massage. At postintervention, intervention mothers have higher maternal self-efficacy than control. Extremely low birth weight (ELBW) intervention infants have significantly higher Bayley Mental Development Index (MDI) scores than ELBW control infants, but no intervention effects are observed among heavier preterm infants. Among infants of families living above federally established poverty thresholds, intervention infants have higher MDI scores than control infants. No intervention effects were found for infants of families living in poverty. Findings emphasize the importance of considering meaningful moderators in evaluations of early intervention effects.
Pulse electrodeposition of tin from sulphate bath
Authors: Mohan S. , Rajasekaran N.
Published: March 2009

In the present work, the pulse electrodeposition of tin from sulphate bath containing SnSO4, H2SO4, phenol sulphonic acid, gelatin and β-napthol has been studied. The influences of pulsed current, duty cycle on the thickness, hardness and current efficiency of the tin deposit were studied. Electrochemical corrosion studies of the deposited tin on mild steel were conducted by potentiodynamic polarisation and electrochemical impedance spectroscopy. Cyclic voltammetry studies using potential sweep of 10 mV s–1 provide information about the potential ranges for tin deposition and stripping. The tin deposit on a brass substrate has been investigated using XRD, SEM and AFM. The XRD analysis revealed that the tin plated is Sn(200) and crystalline. The morphology of tin deposit is a typical fine grained and granular structure as seen from SEM and AFM.
Genome-wide association study to identify novel loci associated with therapy-related myeloid leukemia susceptibility
Authors: Knight Jeffrey A. , Skol Andrew D. , Shinde Abhijit , Hastings Darcie , Walgren Richard A. , Shao Jin , Tennant Thelma R. , Banerjee Mekhala , Allan James M. , Le Beau Michelle M. , Larson Richard A. , Graubert Timothy A. , Cox Nancy J. , Onel Kenan
Published: March 2009

Therapy-related acute myeloid leukemia (t-AML) is a rare but fatal complication of cytotoxic therapy. Whereas sporadic cancer results from interactions between complex exposures and low-penetrance alleles, t-AML results from an acute exposure to a limited number of potent genotoxins. Consequently, we hypothesized that the effect sizes of variants associated with t-AML would be greater than in sporadic cancer, and, therefore, that these variants could be detected even in a modest-sized cohort. To test this, we undertook an association study in 80 cases and 150 controls using Affymetrix Mapping 10K arrays. Even at nominal significance thresholds, we found a significant excess of associations over chance; for example, although 6 associations were expected at P less than .001, we found 15 (Penrich = .002). To replicate our findings, we genotyped the 10 most significantly associated single nucleotide polymorphisms (SNPs) in an independent t-AML cohort (n = 70) and obtained evidence of association with t-AML for 3 SNPs in the subset of patients with loss of chromosomes 5 or 7 or both, acquired abnormalities associated with prior exposure to alkylator chemotherapy. Thus, we conclude that the effect of genetic factors contributing to cancer risk is potentiated and more readily discernable in t-AML compared with sporadic cancer.
Induction of angiogenesis by normal and malignant plasma cells
Authors: Hose Dirk , Moreaux Jérôme , Meissner Tobias , Seckinger Anja , Goldschmidt Hartmut , Benner Axel , Mahtouk Karène , Hillengass Jens , Rème Thierry , De Vos John , Hundemer Michael , Condomines Maud , Bertsch Uta , Rossi Jean-François , Jauch Anna , Klein Bernard , Möhler Thomas
Published: March 2009

Abundant bone marrow angiogenesis is present in almost all myeloma patients requiring therapy and correlated to treatment response and survival. We assessed the expression of 402 angiogenesis-associated genes by Affymetrix DNA microarrays in 466 samples, including CD138-purified myeloma cells (MMCs) from 300 previously untreated patients, in vivo microcirculation by dynamic contrast-enhanced magnetic resonance imaging, and in vitro angiogenesis (AngioKit-assay). Normal bone marrow plasma cells (BMPCs) express a median of 39 proangiogenic (eg, VEGFA, ADM, IGF-1) and 28 antiangiogenic genes (eg, TIMP1, TIMP2). Supernatants of BMPCs unlike those of memory B cells induce angiogenesis in vitro. MMCs do not show a significantly higher median number of expressed proangiogenic (45) or antiangiogenic (31) genes, but 97% of MMC samples aberrantly express at least one of the angiogenic factors HGF, IL-15, ANG, APRIL, CTGF, or TGFA. Supernatants of MMCs and human myeloma cell lines induce significantly higher in vitro angiogenesis compared with BMPCs. In conclusion, BMPCs express a surplus of proangiogenic over antiangiogenic genes transmitting to the ability to induce in vitro angiogenesis. Aberrant expression of proangiogenic and down-regulation of antiangiogenic genes by MMCs further increases the angiogenic stimulus, together leading to bone marrow angiogenesis at various degrees in all myeloma patients.
Interferon-gamma coordinates CCL3-mediated neutrophil recruitment in vivo
Authors: Bonville Cynthia A , Percopo Caroline M , Dyer Kimberly D , Gao Jiliang , Prussin Calman , Foster Barbara , Rosenberg Helene F , Domachowske Joseph B
Published: March 2009

Background

We have shown previously that acute infection with the respiratory pathogen, pneumonia virus of mice (PVM), results in local production of the proinflammatory chemokine, CCL3, and that neutrophil recruitment in response to PVM infection is reduced dramatically in CCL3 -/- mice.

Results

In this work, we demonstrate that CCL3-mediated neutrophil recruitment is coordinated by interferon-gamma (IFNγ). Neutrophil recruitment in response to PVM infection was diminished five-fold in IFNγ receptor gene-deleted mice, although neutrophils from IFNγR -/- mice expressed transcripts for the CCL3 receptor, CCR1 and responded functionally to CCL3ex vivo. Similarly, in the absence of PVM infection, CCL3 overexpression alone could not elicit neutrophil recruitment in the absence of IFNγ. Interestingly, although supplemental IFNγ restored neutrophil recruitment and resulted in a sustained weight loss among CCL3-overexpressing IFNγ -/- mice, CCL3-mediated neutrophil recruitment alone did not result in the pulmonary edema or respiratory failure characteristic of severe viral infection, suggesting that CCL3 and IFN-γ together are sufficient to promote neutrophil recruitment but not pathologic activation.

Conclusion

Our findings reveal a heretofore unrecognized hierarchical interaction between the IFNγ and CCL3, which demonstrate that IFNγ is crucial for CCL3-mediated neutrophil recruitmentin vivo.
The epidemiology of gonorrhoea in Norway, 1993–2007: past victories, future challenges
Authors: Jakopanec Irena , Borgen Katrine , Aavitsland Preben
Published: March 2009

Background

Gonorrhoea, a bacterial infection caused by Neisseria gonorrhoeae, has been increasing in several European countries, particularly among men who have sex with men (MSM) and teenagers. We describe the epidemiology of gonorrhoea in Norway in the recent 15 years in order to guide recommendations on the diagnosis, treatment and prevention of gonorrhoea. An evaluation of the Norwegian Surveillance System for Communicable Diseases (MSIS) in 1994, involving GPs and microbiological laboratories, suggested that the system has a high coverage, capturing over 90% of patients diagnosed with gonorrhoea.

Methods

Using MSIS data on gonorrhoea cases we analysed specific trends by route of transmission, age, gender, anatomical sampling site, antimicrobial resistance and travel history from 1993–2007 and, to focus on more recent trends, from 2003–2007. MSM and heterosexual cases were defined by route of transmission.

Results

From 1993 to 2007, 3601 gonorrhoea cases were reported. MSM cases increased from 10 in 1994 to 109 cases in 2004. From 2003–2007, the incidence of gonorrhoea was 5.4/100,000 person-years (95%CI: 4.9–6.0). Over these five years, MSM accounted for an average of 80 cases per year, of which 69% were infected by casual partners. In the same period, 98% of heterosexually infected had a positive swab from urethra only and only two (0.3%) from the pharynx. Only one woman (0.5%) was positive from the rectum. From 1993 – 2007, antimicrobial resistance results were reported for 3325 N. gonorrhoeae isolates (98% of cultured samples). The proportion resistant to quinolone has risen from 3% in 1995 to 47% in 2007, with 81% of the latter isolated from patients infected in Asia.

Conclusion

The overall incidence of gonorrhoea in Norway remains low, but the increasing number of MSM cases calls for new, more effective approaches to prevention. Infections originating from abroad represent a constant risk of importing antimicrobial resistant N. gonorrhoeae. Due to the prevalence of quinolone resistant N. gonorrhoeae in Norway, third-generation cephalosporins should replace quinolones as the first choice in treatment guidelines. We advocate antimicrobial susceptibility testing for all cases and recommend taking samples for culture from all exposed anatomical sites.
The effects of infliximab therapy on the serum proteome of rheumatoid arthritis patients
Authors: Dwivedi Ravi C , Dhindsa Navjot , Krokhin Oleg V , Cortens John , Wilkins John A , El-Gabalawy Hani S
Published: March 2009

Introduction

Although the clinical effects of infliximab therapy in rheumatoid arthritis have been documented extensively, the biological effects of this intervention continue to be defined. We sought to examine the impact of infliximab therapy on the serum proteome of rheumatoid arthritis patients by means of a mass spectrometry-based approach.

Methods

Sera from 10 patients with rheumatoid arthritis were obtained prior to and following 12 weeks of infliximab therapy using a standard clinical protocol. The sera were immunodepleted of the 12 highest abundance proteins, labeled by the iTRAQ (isobaric tagging for relative and absolute protein quantification) technique, and analyzed by mass spectrometry to identify proteomic changes associated with treatment.

Results

An average of 373 distinct proteins were identified per patient with greater than 95% confidence. In the 3 patients demonstrating the most robust clinical responses, changes of greater than 20% in the serum levels were observed in 39 proteins following treatment. The majority of these proteins were regulated directly or indirectly by tumour necrosis factor-alpha (TNF-α) and nuclear factor-kappa-B, with acute-phase proteins being uniformly down-regulated. A number of proteins, including members of the SERPIN family and S100A8, were down-regulated irrespective of clinical response.

Conclusions

The present study demonstrates that a robust clinical response to infliximab is associated with the down-regulation of a spectrum of serum proteins regulated by TNF-α, and provides a possible basis for defining the broader biological effects of the treatment in vivo.
Foxg1promotes olfactory neurogenesis by antagonizingGdf11
Authors: Kawauchi Shimako , Kim Joon , Santos Rosaysela , Wu Hsiao-Huei , Lander Arthur D. , Calof Anne L.
Published: March 2009

Foxg1, a winged-helix transcription factor, promotes the development of anterior neural structures; in mice lacking Foxg1, development of the cerebral hemispheres and olfactory epithelium (OE) is severely reduced. It has been suggested that Foxg1 acts by positively regulating the expression of growth factors, such as Fgf8, which support neurogenesis. However, Foxg1 also binds Smad transcriptional complexes, allowing it to negatively regulate the effects of TGFβ family ligands. Here, we provide evidence that this latter effect explains much of the ability of Foxg1 to drive neurogenesis in the OE. We show that Foxg1 is expressed in developing OE at the same time as the gene encoding growth differentiation factor 11 (Gdf11), a TGFβ family member that mediates negative-feedback control of OE neurogenesis. Mutations in Gdf11 rescue, to a considerable degree, the major defects in Foxg1-/- OE,including the early, severe loss of neural precursors and olfactory receptor neurons, and the subsequent collapse of both neurogenesis and nasal cavity formation. Rescue is gene-dosage dependent, with loss of even one allele of Gdf11 restoring substantial neurogenesis. Notably, we find no evidence for a disruption of Fgf8 expression in Foxg1-/- OE. However, we do observe both a failure of expression of follistatin (Fst), which encodes a secreted Gdf11 antagonist normally expressed in and around OE, and an increase in the expression of Gdf11 itself within the remaining OE in these mutants. Fst expression is rescued in Foxg1-/-;Gdf11-/- and Foxg1-/-;Gdf11+/- mice. These data suggest that the influence of Foxg1 on Gdf11-mediated negative feedback of neurogenesis may be both direct and indirect. In addition, defects in development of the cerebral hemispheres in Foxg1-/- mice are not rescued by mutations in Gdf11, nor is Gdf11 expressed at high levels within these structures. Thus, the pro-neurogenic effects of Foxg1are likely to be mediated through different signaling pathways in different parts of the nervous system.
Recent developments in large-scale dimensional metrology
Authors: Peggs G N , Maropoulos P G , Hughes E B , Forbes A B , Robson S , Ziebart M , Muralikrishnan B
Published: March 2009

With ever-more demanding requirements for the accurate manufacture of large components, dimensional measuring techniques are becoming progressively more sophisticated. This review describes some of the more recently developed techniques and the state-of-the-art in the more well-known large-scale dimensional metrology methods. In some cases, the techniques are described in detail, or, where relevant specialist review papers exist, these are cited as further reading. The traceability of the measurement data collected is discussed with reference to new international standards that are emerging. In some cases, hybrid measurement techniques are finding specialized applications and these are referred to where appropriate.
Free vibration and buckling analysis of functionally graded deep beam-columns on two-parameter elastic foundations using the differential quadrature method
Authors: Sahraee S , Saidi A R
Published: March 2009

In this research, a differential quadrature method is applied for free vibration and buckling analysis of deep beam-columns composed of functionally graded materials on two-parameter elastic foundations. Derivation of equations is based on the unconstrained higher-order shear deformation theory taking into account the complete effects of shear deformation, depth change, and rotary inertia. It is assumed that the effective mechanical properties of functionally graded (FG) beam-columns are temperature dependent and vary continuously throughout the thickness direction according to volume fraction of the constituents defined by power-law function. The accuracy, convergence, and flexibility of the differential quadrature technique for simply supported FG deep beam-columns with complicated governing differential equations and boundary conditions are examined and verified with the known data in the literature.
Impact load due to railway wheels with multiple flats predicted using an adaptive contact model
Authors: Zhu J J , Ahmed A K W , Rakheja S , Hu Y S
Published: March 2009

Although numerous investigations have been undertaken to study the impact load between railway wheel and rail in the presence of a single wheel flat, little attention was devoted to the case of multiple flats. In practice, it is not uncommon that one wheel develops more than one flat or each wheel on the same axle has a single flat. In this study an adaptive contact model, a two-dimensional roll-plane vehicle model, and a three-dimensional track model are developed to investigate the wheel—rail impact load due to multiple flats. Unlike the commonly used Hertzian contact model, the adaptive contact model takes into account the asymmetry of the contact patch as the wheel flat enters and leaves the contact patch. Two scenarios of multiple flats are considered in this investigation. One deals with two flats on the same wheel defined by their size and relative position, and the other deals with a single flat on each wheel of the same axle. In each case, the induced impact loads are compared with those due to a single flat. The results suggest that the magnitude of impact force attributed to the second flat entering the contact region is strongly affected by the responses due to the preceding flat, depending upon the flat geometry, relative co-ordinates of the flats and the operating speed. The results further suggest that the length of a flat alone, which is commonly regarded as wheel removal criteria, may not be adequate when multiple flats are present.
Performance estimation of variable geometry turbines
Authors: Qiu C , Song H-F , Wang Y-H , Huang M-H
Published: March 2009

The concept of using variable geometry to alter the characteristics of turbomachinery has been in existence for many years. Advanced gas turbine engines, especially for aeronautical and naval applications, will extensively use variable geometry turbines and, therefore, a tool must exist that is capable of evaluating the performance of such turbines right from the conceptual stage. With this in mind, a new method based on the improved flow model originally proposed by Wang is presented. The improvements resolve two aspects of the flow model that restrict its widely used possibility: that is, the flow model can be applied only to turbines that work under a subcritical condition and it cannot be applied to variable geometry turbines. After these improvements, the new method can be applied to both single-stage turbines and multi-stage turbines with variable geometry used in any stage. To prove this, two examples are presented in this article. One example is a single-stage variable geometry turbine; the predicted results are examined against the experimental results and a satisfactory conformity is obtained. The good agreement shows that the new method is capable of predicting the performance of variable geometry turbine accurately. The other example is a four-stage turbine with variable geometry used in the first stage. All the results show that the ‘bottom-up’ method is an effective way to predict the performance of variable geometry turbine and it can be used extensively.
Preparation and tribological behaviour of multiply-alkylated cyclopentane-1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane dual-layer film on diamond-like carbon
Authors: Ma J Q , Mo Y F , Bai M
Published: March 2009

Hybrid dual-layer film was prepared on diamond-like carbon (DLC) surface by depositing mobile lubricant multiply-alkylated cyclopentane (MAC) on 1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane self-assembled monolayers (FDTS-SAMs). The formation of comparatively uniform FDTS-SAMs on DLC surface was verified by static contact angle measurement, X-ray photoelectron spectrometer, and atomic force microscope (AFM). AFM result showed that a high density of regular but discrete nano-scale island-like liquid droplets of MAC were distributed on DLC surface with an interlayer of FDTS-SAMs to form hybrid AC-FDTS dual-layer film. The average diameter and height of MAC droplets on FDTS-SAMs are 30 nm and 35 Å, respectively, and the area covered by MAC droplets is ∼60 per cent. The tribological behaviour of the resulting hybrid film was evaluated on a pin-on-plate test rig using Zdol-2000 film and FDTS-SAMs as reference. The result showed that hybrid MAC-FDTS dual-layer film exhibited the best reducing-friction capability, load-carrying capacity, and durability compared with Zdol-2000 and FDTS-SAMs at applied loads of 50–250 mN. This may be attributed to the self-healing ability of the mobile MAC lubricant to diffuse and cover the damaged or defective areas of the substrates.
Effects of friction on tribo-magnetization mechanisms for self-mated iron pairs under dry friction condition
Authors: Chang Y-P , Yur J-P , Chu L-M , Chou H-M , Hwang Y-C
Published: March 2009

The effects of friction on tribo-magnetization mechanisms for self-mated iron pairs under dry friction were experimentally investigated in this study. By comparing the effects of sliding speeds and normal loads on surface magnetization, the physical contradiction in frictional magnetization can therefore be classified. Results showed that severe friction phenomena are the prerequisite conditions for tribo-magnetization to occur. The maximum dynamic saturated value of tribo-magnetization for the self-mated iron pairs during the friction process was found to be only about 18 G but rapidly decreased to the range of 0-1 G after the test. It was also found that tribo-magnetization decreased significantly with increasing sliding speed. This was due to a rise in surface temperature and the presence of oxide materials at the actual contact areas from higher sliding speeds. The magnetic domains were also randomly oriented due to thermal vibration, which explained surface demagnetization with increasing sliding speed. In general, the average tribo-magnetization was inversely proportional to the sliding speed. Under small normal loads, tribo-magnetization was insignificant. For normal loads exceeding 30 N, the average tribo-magnetization increased linearly with increasing normal load. It was revealed that variations of the average tribo-magnetization coincided with wear losses under heavy normal loads. The reasons were that as the oxide film broke, fresh ferromagnetism was exposed to severe wear and material transfer. The orientation of the magnetic domains was caused by both frictional activation and the earth's magnetic field. Tribo-magnetization was thus significantly increased by friction and wear with increasing normal load. Finally, this study proposed two perspectives on energy and material to clarify the physical contradictions of the tribo-magnetization.
The surface magnetization approach on assessing tribological properties of steels with different TiN coatings
Authors: Chang Y-P , Hung Y-Y , Chu L-M , Yur J-P , Lin C-H
Published: March 2009

The dynamic tribological properties of thin films over the past decades have been monitored using friction coefficient, and that is despite the relatively low sensitivity of the measurement in many sliding conditions. The search is therefore on improved physical measurements other than friction coefficient to monitor the film tribological characteristics in sliding contacts. This article introduces the novel technology of using surface magnetization variations for evaluating the wear-resistant properties of thin ceramic films. The experiment was conducted on pairs of SUS304 steel rubbing with SKD11 steel substrate coated with different TiN films (physical vapour deposit and chemical vapour deposit) under different normal loads under dry friction condition. By monitoring the dynamic variations of surface magnetization and friction coefficient in conjunction with SEM observations of the wear tracks, the effects of normal loads on the friction and wear properties for the die surfaces coated with different TiN films were investigated. The experimental results showed that the continuous surface magnetization variations can be used to determine the onset of film fracture and the endurance life of the ceramic film more accurately than that by friction coefficient variations. Therefore, the novel method of using surface magnetization variations does show great potential for evaluating the tribological properties of steels with different TiN films.
Development of an atomic force microscope closed fluid cell for tribological investigations of large samples in chemically aggressive environments
Authors: Gebeshuber I C , Holzer D , Goschke R , Aumayr F , Störi H
Published: March 2009

Many atomic force microscopes (AFM) are nowadays equipped with closed fluid cells. Most of these closed fluid cells have small volume, limiting the maximum sample size, and, furthermore, do not allow for investigations in chemically aggressive environments such as solvents. The closed fluid cell for MFP-3D, the atomic force microscope from Asylum Research, Santa Barbara, CA, has a glass base and is mainly intended for investigations of flat transparent biological samples.

Starting from the MFP-3D closed fluid cell, a fluid cell tailored for investigations in tribologically relevant environments, e.g. at extreme mechanical and chemical conditions which may vary with time, was developed. Samples of various shapes and sizes can thus be investigated in controlled environments, be they fluid (e.g. solvents) or gaseous (e.g. corrosive gases).

First results of AFM nanotribology experiments using this fluid cell are presented. Among the systems of interest are additives diluted in solvents adsorbing to surfaces and spreading and persistence of ionic liquids on tribologically stressed surfaces.
The sliding friction and wear properties of poly(vinylidene fluoride) composites filled with carbon fibres
Authors: Jian L
Published: March 2009

Tribological performance of poly(vinylidene fluoride) (PVDF) and carbon fibre reinforced PVDF under dry sliding condition is studied. Different contents of carbon fibres were employed as reinforcement. All filled and unfilled polyimide composites were tested against the CGr15 ball and representative testing was performed. The effects of carbon fibre content on tribological properties of the composites were investigated. The worn surface morphologies of neat PVDF and its composites were examined by scanning electron microscopy and the wear mechanisms were discussed. Moreover, all filled PVDFs have superior tribological characteristics to unfilled PVDFs. The optimum wear reduction was obtained when the content of carbon fibre was 20 vol%.
Heat of Formation for the Benzoyl Cation by Photoionization Mass Spectrometry
Authors: Traeger John C.
Published: March 2009

Dissociative photoionization mass spectrometry has been used to measure the PhCO+ appearance energies for several benzoyl compounds. Based on these threshold measurements, an experimental 298 K heat of formation of 738.8 ± 3.3 kJ mol−1 is obtained for the benzoyl cation. The experimental results are supported by high-level ab initio calculations.
Positive Ion Chemistry of SiH4/NF3 Gaseous Mixtures Studied by Ion Trap Mass Spectrometry
Authors: Antoniotti Paola , Operti Lorenza , Rabezzana Roberto , Turco Francesca , Borocci Stefano , Grandinetti Felice
Published: March 2009

The positive ion chemistry occurring in silane/nitrogen trifluoride gaseous mixtures has been investigated by ion trap mass spectrometry. Reaction sequences and rate constants have been determined for the processes involving the primary ions SiH n+ ( n = 0–3) and NF x+ ( x = 1–3) and the secondary ions obtained from their reactions with SiH4 and NF3. The SiH n+ efficiently react with NF3 and undergo cascades of abstraction and scrambling reactions which form the fluorinated and perfluorinated cations SiHF m+ ( m = 1, 2), SiH2F+ and SiF x+ ( x = 1–3). Fluorinated Si2-clusters such as Si2H2F+, Si2H3F+ and Si2H5F+ were also observed. The reaction of both SiH3+ and SiH2F+ with NF3 produces the elusive fluoronitrenium ion NHF+. Any NF x+ reacts with SiH4 mainly by charge transfer. Additional ionic products are, however, observed which suggest intimate reaction complexes. Worth mentioning is the formation of SiNH2+ from the reaction of both NF+ and NHF+ with SiH4. The primary ions NF2+ and SiH3+ are also “sink” species in our observed chemistry.
Small (Poly)Unsaturated Oxygen Containing Ions and Molecules: A Brief Assessment of Their Thermochemistry Based on Computational Chemistry
Authors: Holmes John L. , Jobst Karl J. , Terlouw Johan K.
Published: March 2009

The CBS-QB3, CBS-APNO and Gaussian-3 model chemistries have been used to determine the ionic and neutral heats of formation and the adiabatic ionization energies ( IEa) derived therefrom, for the ca 30 principal isomers of the C3H2O•+ and the C4H4O•+ families of radical cations. Theory and experiment are in excellent agreement for those molecules whose experimental IEa has been accurately measured. In contrast, large deviations from the computed values were found for a great many ionic heats of formation reported in the literature. These deviations largely arise from the uncertainty in the heat of formation of the corresponding neutral species for which often only a rough estimate is available. A useful by-product of this study is that it permits the evaluation of new Benson-type group additivity ( GA) terms appropriate for highly unsaturated oxygen containing molecules. Several new GA terms are proposed but it is also argued that a single GA term for the ketene function cannot be defined.
Characterization of Oligodeoxynucleotide Fragmentation Pathways in Infrared Multiphoton Dissociation and Electron Detachment Dissociation by Fourier Transform Ion Cyclotron Double Resonance
Authors: Yang Jiong , Håkansson Kristina
Published: March 2009

Infrared multiphoton dissociation (IRMPD) is a vibrational excitation tandem mass spectrometric fragmentation method valuable for sequencing of oligonucleotides. For oligodeoxynucleotides, typical product ions correspond to sequence-specific 5′ ( a-base) and their complementary 3′ w-type ions from carbon–oxygen bond cleavage at the 3′ position of the deoxyribose from which a nucleobase is lost. Such fragmentation patterns are also observed in collision activated dissociation (CAD). The CAD oligodeoxynucleotide fragmentation mechanism has been characterized in detail. By contrast, fragmentation schemes in IRMPD have not been rigorously established. In this paper, we apply, for the first time, Fourier transform ion cyclotron double resonance (DR) experiments to characterize IRMPD fragmentation pathways of oligodeoxynucleotide anions. Our results suggest that neutral base loss precedes backbone fragmentation but that T-rich oligodeoxynucleotides fragment via a different mechanism, similar to the mechanisms proposed for CAD. We also extend the DR approach to characterize intermediates in electron detachment dissociation of hexamer oligodeoxynucleotides. Here, we found that charge reduced radical precursor ions constitute major intermediates for dT6, d(GCATAC) and d(GCATGC). Furthermore, ( a/ z–T) ions ( z ions correspond to C–O bond cleavage on the other side of a backbone phosphate group as compared to the formation of a ions) mainly originate from secondary fragmentation of a/ z radical ions for the oligodeoxynucleotide dT6.
Gas-Phase Reactivity of Acylphenols in Electrospray and Matrix-Assisted Laser Desorption Ionization Mass Spectrometry
Authors: Schmitz-Afonso Isabelle , Guérineau Vincent , Maia-Grondard Alessandra , Awang Khalijah , Litaudon Marc , Guéritte Françoise , Laprévote Olivier
Published: March 2009

Acylphenols from Myristica crassa were identified based on liquid chromatography high-resolution mass spectrometry and liquid chromatography tandem mass spectrometry (MS/MS) experiments. Two types of compound were found in the extract of the plant: monomeric (malabaricone B and C) and dimeric compounds (C–C bonded biphenyl and C–C bonded phenyl–linear carbon chain). Evidence of formation of covalent dimeric ions during the electrospray ionization and matrix-assisted laser desorption ionization (MALDI) processes was established. [2M–3H]− dimeric ions were detected on the mass spectra of each monomeric compound during high-performance liquid chromatography separation. The MS/MS spectra of those species were compared to the MS/MS spectra obtained for the dimeric compounds synthesized by the plant. Fragmentation pathways were studied for the two classes of dimer. The dimeric ions formed in the ion source were C–C bonded biphenyl compounds. Further evidence was obtained from MALDI experiments: increase in the extraction delay time leads to an increase of the dimeric ions relative abundance. Their formation is based on the high reactivity of phenols or phenolate ions which are easily oxidized yielding phenoxy radicals.
Redshift or Adduct Stabilization—A Computational Study of Hydrogen Bonding in Adducts of Protonated Carboxylic Acids
Authors: Olesen Solveig Gaarn , Hammerum Steen
Published: March 2009

It is generally expected that the hydrogen bond strength in a D–H•••A adduct is predicted by the difference between the proton affinities (Δ PA) of D and A, measured by the adduct stabilization, and demonstrated by the infrared (IR) redshift of the D–H bond stretching vibrational frequency. These criteria do not always yield consistent predictions, as illustrated by the hydrogen bonds formed by the E and Z OH groups of protonated carboxylic acids. The Δ PA and the stabilization of a series of hydrogen bonded adducts indicate that the E OH group forms the stronger hydrogen bonds, whereas the bond length changes and the redshift favor the Z OH group, matching the results of NBO and AIM calculations. This reflects that the thermochemistry of adduct formation is not a good measure of the hydrogen bond strength in charged adducts, and that the ionic interactions in the E and Z adducts of protonated carboxylic acids are different. The OH bond length and IR redshift afford the better measure of hydrogen bond strength.
Variability of N-Terminal Probrain Natriuretic Peptide in Stable Chronic Heart Failure and Its Relation to Changes in Clinical Variables
Authors: Frankenstein Lutz , Remppis Andrew , Frankenstein Joerdis , Hess Georg , Zdunek Dietmar , Slottje Karen , Katus Hugo A , Zugck Christian
Published: March 2009

Background: We investigated the variability of N-terminal probrain natriuretic peptide (NT-proBNP) and its relation to known confounding variables in patients with stable chronic heart failure who were on a stable optimized medication regimen.

Methods: At 4 sampling intervals (14-day, 1-month, 2-month, and 3-month) the results for NT-proBNP measurements and several clinical variables were measured in samples from 41 patients with chronic systolic dysfunction who met 21 prespecified criteria for stability.

Results: Mean within-person NT-proBNP variabilities expressed as percentage CV were 17.6%, 18.9%, 15.5%, and 16.2% at 14-day, 1-month, 2-month, and 3-month follow-up, respectively, and the corresponding reference change values were 34.6%, 52.5%, 43.1%, and 45.0%, respectively. Within-person variability of NT-proBNP was not found to be associated with renal function, weight, or waist circumference. Likewise, age, sex, baseline NT-proBNP, New York Heart Association functional class, and ejection fraction did not influence variability of NT-proBNP. The index of individuality ranged from 0.07–0.15 depending on the time interval between test results.

Conclusions: Although other reported studies have revealed variations in the range of 80%, in this prespecified stable heart-failure population variation of NT-proBNP at 14-day, 1-month, 2-month, and 3-month follow-up was lower and was not related to renal function or weight. In view of the low index of individuality we observed, within-person variation is quite low compared to between-person variation. Consideration of these facts is important for the interpretation of clinical trials and the use of NT-proBNP in monitoring patients with heart failure.
Role of Monitoring Changes in Sensitive Cardiac Troponin I Assay Results for Early Diagnosis of Myocardial Infarction and Prediction of Risk of Adverse Events
Authors: Apple Fred S , Pearce Lesly A , Smith Stephen W , Kaczmarek Jason M , Murakami MaryAnn M
Published: March 2009

Background: We sought to determine the diagnostic accuracy of the cardiac troponin I (cTnI) VITROS® Troponin I-ES assay for early detection of acute myocardial infarction (AMI) and for risk prediction of adverse events in patients with symptoms of acute coronary syndrome (ACS).

Methods: cTnI was measured on admission and approximately 6 h postadmission in 381 patients. The 99th percentile cTnI concentration (0.034 μg/L) and change [delta (δ)] between admission and follow-up concentrations were evaluated in diagnostic sensitivity and specificity calculations. Risk of cardiac event or death within 60 days was evaluated by Cox proportional hazards regression.

Results: AMI occurred in 52 patients. Diagnostic sensitivities (95% CI) of admission and follow-up cTnIs for AMI were 69% (55%–81%) and 94% (84%–99%), respectively. The corresponding specificities (95% CI) were 78% (73%–82%) and 81% (77%–85%), and ROC curve areas were 0.82 vs 0.96 (P < 0.001). Deltas between admission and follow-up cTnI >30% had a sensitivity of 75% (95% CI 61%–86%) and a specificity of 91% (95% CI 87%–94%). During follow-up, 1 cardiac death, 2 noncardiac deaths, 52 AMIs, 6 coronary artery bypass grafts, and 43 percutanous coronary interventions occurred in 62 patients. A δ cTnI >30%, when added to either initial cTnI >0.034 μg/L or follow-up cTnI >0.034 μg/L, improved risk stratification for cardiac event or death (P < 0.001).

Conclusions: Admission cTnI measured by the VITROS ES assay is a sensitive biomarker for detection of AMI. Utilizing >30% cTnI δ in addition to either the baseline or follow-up concentration improved both specificity and risk assessment in patients presenting with symptoms of ACS.
Influence of Aging on High-Temperature Creep Crack Growth in Type 304H Stainless Steel
Authors: Buchheim GM , Becht C , Nikbin KM , Dimopolos V , Webster GA , Smith DJ
Published: March 2009

Stress rupture tests on smooth and notched tensile bars and creep crack growth measurements under both static and cyclic loading have been made on virgin (new) solution annealed and naturally aged Type 304H stainless steel at 760C. The naturally aged material was taken from a component which had been in service for 15 years at temperatures in the range 690 to 725C. It is known that some deterioration in properties occurs with aging in Type 304 stainless steel and that this could affect sensitivity to cracking. This paper shows that crack growth rate can be characterized in terms of the creep fracture mechanics parameter C* and that the behavior of the new and aged materials can be rationalized in terms of their creep ductilities and the influence of ductility on the state of stress developed at a crack tip. Furthermore, the paper demonstrates that lower and upper bound crack growth rates can be estimated approximately from uniaxial creep rupture data.
Mechanism of Vision—A Review
Authors: Johnston JW
Published: March 2009

The human retinal image is a pattern of light and dark that differs from a picture within the central nervous system. A remarkable characteristic is the “saccade,” a very fast flicking of the eyeballs such that a new focus of the image is formed on the cone cells of the central pit every few milliseconds. The saccade is especially important to reading when the day-vision cones function. The night-vision rods do not add much to day vision but are a fourth mechanism in respect to the three kinds of cones which enable the brain to distinguish contrasts between spectral hues. Despite the infinite variety of textures and settings with which colors are often perceived, there is a limited degree of color constancy of objects under varying conditions of brightness, size, and shape.
Swelling and Tensile Property Evaluations of High-Fluence EBR-II Thimbles
Authors: Fish RL , Straalsund JL , Hunter CW , Holmes JJ
Published: March 2009

The effects of very high neutron fluences on tensile properties and swelling of 300-series austenitic stainless steel were evaluated by destructive examination of several EBR-II thimbles that had accumulated fluences approaching 1.2 x 1023 n/cm2 (En > 0.1 MeV). Irradiation temperatures ranged from 370 to 470 C (698 to 878 F).

Immersion density measurements on control or safety rod thimbles 3D1, 5C3, 5A3, and 3A1 indicate that swelling increases with neutron fluence. Maximum measured volume changes are about 11 percent at 1.1 x 1023 n/cm2 (En > 0.1 MeV) and temperatures near 420 C (788 F). No indications of saturation were observed; in fact, swelling rates increase with increasing fluence over the whole range of fluences investigated. Anomalous swelling behavior was observed in control rod thimble 5A3. In this component, which may have been subjected to mechanical constraint, swelling gradients were found to be much lower than anticipated on the basis of the corresponding gradients in irradiation conditions. This behavior may be the result of an effect of stress on swelling not previously encountered.

Tensile property changes are similar to those classically observed. When irradiation and test temperatures are equivalent, yield strength (0.2 percent offset) increases rapidly at low fluences and becomes fluence-independent at high fluence levels (>7 × 1022 n/cm2, En > 0.1 MeV). Uniform elongation correspondingly decreases with increasing fluence and appears to saturate near 0.5 percent at higher fluence levels. This transition in fluence dependence of the properties is associated with a transition in fracture mechanism. The transition occurs from the usual homogeneous plastic dimpling fracture at low fluences to an extremely heterogeneous channel fracture at high fluence levels.
Neutron Irradiation Damage in a Precipitation-Hardened Aluminum Alloy
Authors: King RT , Jostsons A , Farrell K
Published: March 2009

A 6061 aluminum alloy target sleeve from the high flux isotope reactor, originally in a precipitation-hardened condition, was examined for neutron radiation damage after exposure to a maximum fast fluence of 9.2 × 1022 n/cm2 (E > 0.1 MeV) and a thermal fluence of 1.38 × 1023 n/cm2 at 60 C (140 F). Voids and a transmutation-produced silicon precipitate were found to cause about 1.1 percent internal swelling; a surface oxide scale contributed additional swelling. Irradiation-induced strength increases were measured at test temperatures in the range 25 to 200 C (77 to 392 F) and are accounted for in terms of the observed silicon precipitate and an associated dislocation structure. There was also a loss of ductility that was most severe at 200 C. The fracture mode appeared to remain transgranular over the range of test temperatures.
Fatigue Behavior of Irradiated Thin-Section Type 348 Stainless Steel at 550 F (288 C)
Authors: Smith HH , Shahinian P
Published: March 2009

Fatigue life and crack growth rate comparisons have been made of irradiated and unirradiated specimens of Type 348 stainless steel as a function of total strain amplitude. Notched specimens were cycled at resonance in reverse bending in dry air at constant amplitude, and crack growth rates were determined from changes in resonant frequency of vibration. Neutron irradiation to a fluence of 1.5 × 1021 n/cm2 > 0.1 MeV produces approximately an order of magnitude increase in fatigue life at a total strain of 0.20 percent. At lower strains irradiated fatigue life appears to approach an endurance limit and the increase in life becomes very large. The effects on life are attributed to decreased crack growth rates in the irradiated material. Thus, the results in dry air indicate that the fatigue performance at 550 F (288 C) of thin-section reactor components of Type 348 stainless steel should not be reduced by irradiation characteristic of pressurized water reactors. The influence of water vapor on the fatigue characteristics of irradiated Type 348 stainless steel is being investigated in a separate study.
Chapter 41—Chemical Reactions of Carbonate Aggregates in Cement Paste
Authors: Walker HN
Published: March 2009

It has long been recognized that no aggregate is completely inert in the environment of portland cement paste. This environment is always at least as alkaline as a saturated solution of calcium hydroxide and may for certain sources of cement exceed this alkalinity [1]. We only need to consider those reactions which take place at a rate sufficient to affect the concrete during its normal life span. Carbonate aggregate reactions may be beneficial, innocuous, or deleterious.
Chapter 43—Mixing and Curing Water for Concrete
Authors: McCoy WJ
Published: March 2009

This paper is concerned primarily with the significance of tests of various types of waters for mixing and curing concrete and makes no attempt to include the effect of quantity of mixing water. Almost all natural waters, fresh waters, and waters treated for municipal use are satisfactory as mixing water for concrete if they have no pronounced odor or taste. Because of this very little attention is usually given to the water used in concrete, a practice that is in contrast to the frequent checking of the cement and aggregate components of the concrete mix.
Chapter 50—Pumpability Aids for Concrete
Authors: Valore RC
Published: March 2009

An essential requirement of concrete for any use is that it be transported from mixer to forms without separation of water, cementing materials, or aggregates, with sufficient retention of consistency to permit economical consolidation. To achieve that end, it is an objective in proportioning the ingredients of concrete to obtain a blend of solid materials, from the finest cement grain to the largest particle of coarse aggregate, which, when consolidated, will have an interstitial void structure of minimum volume, and relatively low permeability and surface area. The latter requirements would appear to be contradictory since permeability of a bed of granular solids is inversely related to its surface area. Permeability of the aggregate void system should be low enough to prevent permeation by water or cement paste under pressure. Surface area should be low enough to permit the use of economical amounts of cement and suitable water/cement (w/c) ratios to provide a volume of paste sufficient to saturate the aggregate voids and form workable cohesive concrete.