Hydration heat kinetics of concrete with silica fume

The objective of this study was to evaluate the influence of silica fume on the hydration heat of concrete. Portland cement was replaced by silica fume in amounts from 10 % to 30 % by mass in concrete with w/(c+sf) ratios varying between 0.25 and 0.45. A superplasticizer was used to maintain a fluid consistency. The heat of hydration was monitored continuously by a semi-adiabatic calorimetric method for 10 days at 20 °C. The calorimetric study indicated that the hydration was modified by the presence of silica fume. In the early stages, the silica fume showed a high activity and accelerated the hydration rate as compared to that of the reference concrete. The fine silica fume particled provided nucleation sites for hydrates growth. Then the pozzolanic activity took over and increased both strength and the hydration heat. A substitution of Portland cement by 10% with silica fume produced greater strength and cumulative heat of hydration as compared to that of the reference concrete.     

Ultra-Low Noise Charge Sensitive Preamplifier for Scintillation Detection with Avalanche Photodiodes in PET Applications

The need for compact, fast, low-noise front-end electronics in high resolution positron emission tomography (PET) has prompted this effort to design a preamplifier suitable for avalanche photodiode-based scintillation detectors. Due to the small signals from the detectors (< .03 pC/MeV), a preamplifier with ultra-low noise performance in the 5 to 20 MHz range is essential to achieve the timing resolution required by the PET application. Out of many available technologies, a new third generation MOSFET wqas selected and implemented as input transistor in an original charge sensitive (CSP) design. Performance among the best reported to date are obtained. The new design was implemented as a dual-channel preamplifier in high density hybrid (thick film) technology.     

Kovacic's algorithm and its application to some families of special functions

We apply the Kovacic algorithm to some families of special functions, mainly the hypergeometric one and that of Heun, in order to discuss the existence of closed-form solutions. We begin by giving a slightly modified version of the Kovacic algorithm and a sketch proof.     

Lamb shift measurements in high Z hydrogenic ions

This paper presents a possible technique for the measurement of the ground state Lamb shift in hydrogenic krypton, Kr³⁵⁺, via a comparison of the Lyman α and Balmer β wavelengths. Measurements of the yields of the Lyman α transitions in Kr³⁵⁺ using krypton beams at 18.6, and $\text{34 MeV}\text{A}$ are described.     

Effect of influenza vaccine on bronchoprovocation testing in normal subjects

A study of 55 nonasthmatic patients was undertaken to determine if recent influenza vaccination is a justifiable exclusionary criteria for bronchoprovocation testing. Healthy subjects without history of asthma and with negative methacholine challenge tests were given an intramuscular injection of killed influenza vaccine. Methacholine challenge testing was repeated 24 h later. While a statistically significant decline in FEV1 at 188 methacholine dose units was demonstrated (p < 0.018), this was not clinically significant; none of the 55 subjects converted a negative test to positive. We conclude that recent influenza vaccination is not a sufficient exclusionary criterion for methacholine challenge testing. Positive results in a patient recently vaccinated would still indicate asthma in the correct clinical setting.     

Atomic-scale APFIM and TEM investigation of grain boundary microchemistry in Astroloy nickel base superalloys

Electron microscopy and atom-probes techniques, including 3D (three-dimensional) atom-probe, were applied to the investigation of grain-boundary (GB) microchemistry and interfacial segregation phenomena in nickel base superalloys, Astroloy. Diffraction patterns and EDX microanalyses exhibit the presence of intergranular M₂₃C₆ chromium enriched carbides as well as intragranular TiC precipitates. Complex phases containing Zr, C and S were also observed. Three-dimensional images as provided by the tomographic atom-probe revealed the presence of a strong segregation of both boron and molybdenum at grain boundaries. Considerable chromium enrichment at γ′-γ′ grain boundaries and slight carbon segregation to GBs, whatever their chemical nature, were also detected. All these segregants are distributed in a continuous manner along the boundary over a width close to 0.5 nm. Experiments show that segregation occurs during cooling and more probably between 1200 and 800°C. Boron, chromium and molybdenum GB enrichments are thought to be mainly controlled by an equilibrium segregation process. No segregation of zirconium was detected.     

Ovarian steroid modulation of neurokinin contents in hypothalamus, pituitary, trigeminal nucleus, and cervical spinal cord of the ovariectomized female rat

Ovariectomized rats were treated with estradiol benzoate (EB) and progesterone in conditions known to negatively and positively regulate gonadotropin secretion. Injection with EB decreased the plasma concentration of substance P at the time of the positive feed-back exerted by EB on gonadotropin secretion, while having no effect on the plasma concentration of neurokinin A. In the hypothalamus, EB injection enhanced the substance P and neurokinin A content, while progesterone reduced the substance P content. In the anterior pituitary, the substance P content was increased after progesterone, and this increase was blocked by EB. Conversely, in the posterior pituitary, the substance P content was reduced after progesterone, and this effect was enhanced by EB. In the trigeminal nucleus, the substance P content was increased after progesterone and EB, while only progesterone affected neurokinin A content. Finally, in the cervical spinal cord, the substance P and neurokinin A contents were reduced after EB. We conclude that neurokinin contents are controlled by ovarian steroids not only in the hypothalamo-pituitary complex but also in the trigeminal nucleus and the cervical spinal cord.     

Practical implications of the phase-compositional assessment of lipid-based food products by time-domain NMR

The objective of this work is to determine the solid fat content (SFC) of the fat-oil phase in oil-in-water (O/W) emulsions, i.e., the droplet SFC, using transverse relaxation decay deconvolution (TRDD) analysis. The TRDD NMR experiment classifies protein protons as mobile, semimobile, and nonmobile. Hence, protein contributes more or less to the solid content detected by TRDD as a function of pH, protein content, and protein denaturation. By taking into account the protein contribution to the overall solid content, one can estimate the droplet solid content in O/W emulsions. The SFC can then be deduced if one converts the ingredients' mass fraction into ingredients' proton fraction using the ingredients' proton densities.