Chloride migration coefficient of self-compacting concrete

In this article laboratory and analytical studies of the chloride migration coefficient, D, are presented. The result of studies on chloride migration of Self-Compacting Concrete, SCC, are compared with the corresponding properties of normal concrete with the same water-cement ratio, w/c and air content. Both 28 and 90 days' age applied at the start of the testing. Six SCC were studied and 2 NC, all with w/c=0.39. The effect of normal and reversed order of mixing (filler last), increased amount of filler, type of filler, limestone powder, increased air content and large hydrostatic concrete pressure were investigated.

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Résumé Cet article traite des études en laboratoire et des analyses concernant le coefficient de migration du chlorure. Le résultat des études sur l'admission en chlorure du béton autocompactant a été comparé avec les propriétés de celles d'un béton courant ayant le même taux d'eau/ciment et la même teneur en air. Des bétons de 28 et de 90 jours ont été utilisés au début des tests. L'étude a porté sur 6 bétons auto-compactants et 2 bétons normaux, tous ayant un taux d'eau/ciment de 0,39. C'est dans ce contexte qu'a été étudiée l'influence d'un mélange normal et inversé (dernier apport), de l'augmentation de la quantité de matériau de remplissage, du type de matériau de remplissage, de la poudre de pierre à chaux, de l'augmentation de la teneur en air et d'une forte compression hydrostatique du béton.

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Editorial Note Dr. Bertil Persson is a RILEM Senior Member. He participates in RILEM TCs LTP' Life time performance of materials and structures’, URM ‘Use of recycled materials’, 196-ICC ‘Internal curing of concretes’ and 195-DTD ‘Recommendation for test methods for autogenous deformation and thermal dilation of early age concrete’.     

Surface roughness measurement on machined surfaces using angular speckle correlation

Surface roughness is of great importance in fields, such as tribology, semiconductor technology and medicine. Stylus techniques, in which a stylus is drawn along the surface and the vertical movement of the stylus is recorded, have been used traditionally in measuring surface roughness. Non-contact methods, such as optical ones, have the advantage that they can be used for the in-process measurement of surface roughness. In this paper, results of the measurement of surface roughness using angular speckle-correlation on machined surfaces are presented. Surfaces of approximately 1.6 < R_a < 6.3 μm have been measured, the surfaces being classified in the same manner as when using a stylus instrument. ASC is a technique that also allows in-process measurement of the roughness of surfaces on machined surfaces. A new technique to achieve increased repeatability by using an angle detection unit is also presented in this paper.     

Hyaluronan in human cerebrospinal fluid

We studied the concentration of hyaluronan in cerebrospinal fluid (CSF) in various diseases and attempted to define its reference interval. A radioassay utilizing cartilage proteins with affinity for hyaluronan was used in determining the concentration of 200 lumbar and 27 ventricular CSF specimens and 11 brain cyst fluids. Molecular weight distributions were determined by gel chromatography and localization in brain tissue by histochemistry. The hyaluronan level of lumbar CSF showed an increase with age; comparatively healthy children had (mean +/- SD) 50 +/- 41 micrograms/L (n = 40) and adults 166 +/- 77 micrograms/L (n = 9); i.e. significantly different values. The highest level was recorded in a patient with meningitis (> 8000 micrograms/L). More than 4000 micrograms/ L was noted in a patient with tumour metastasis in the cerebellum. Significantly elevated levels were especially found with spinal stenosis, head injury and cerebral infarction, but also in inflammatory medical disorders, hydrocephalus and encephalitis. We found no significant increase in multiple sclerosis and some other neurological diseases. Ventricular CSF of adults contained significantly less hyaluronan (53 +/- 73 micrograms/L; n = 16) than lumbar CSF. Hyaluronan in cyst fluids varied from 31 to 25,000 micrograms/L. Weight average molecular weight of hyaluronan in CSF was 2.9-3.0 x 10(5) and in brain tumour cyst fluid 2.4 x 10(6). In search for the origin of hyaluronan in CSF it was found that its concentration in the choroid plexus and leptomeninges was low, but that hyaluronan was accumulated in the superficial layer of the cerebral cortex. Continued screening for hyaluronan in CSF may be valuable in cases of inflammatory diseases, tumours and obstruction to CSF flow.     

In situ ATR-FTIR studies of the aluminium/polymer interface upon exposure to water and electrolyte

Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) with the Kretschmann configuration was applied for in situ studies of the transport of water and ionic species through a polymer film to an aluminium/polymer interface. The time dependent intensity changes of the infrared bands of water were used to follow the transport of water to the aluminium/polymer interfacial region and a NaSCN solution was employed as model electrolyte to follow the transport and accumulation of thiocyanate ions. Apart from water sorption and ion transport, the main processes identified were corrosion/oxidation of the aluminium surface and swelling of the polymer film. The method proved to be useful for detailed in situ studies of changes at a polymer coated metal surface, such as oxidation and surface film formation on the metal. It should also be possible to study the effects of defects and pores in the polymer film on the transport properties of water and ions to the metal/polymer interface, as well as adsorption and other chemical reactions and physical interactions in the metal/polymer interfacial region.     

Factors affecting women to practise breast self-examination

The aim of the study was to identify factors of decisive importance for women's motivation to perform breast self-examination (BSE), which could form the basis of an intervention programme. Interviews were conducted in 1994 with 48 women focusing on four different areas: 1) why the women examined did not examine their breasts, 2) the influence of their upbringing, 3) information or education previously received about the method of examination, and 4) other types of self-care. The findings were summarized under the following categories: feelings, experiences, and lifestyle. Anxiety/fear of discovering a lump and faith/trust in one's own ability to perform the examination were dominating factors influencing the practice or non-practice of BSE. However, there was a general need for knowledge, theoretical as well as practical, among the women studied. They also needed help to identify a strategy to enable them to remember to perform the examination. In order to make BSE a habit, education about BSE ought to be provided to girls at school. The important role of nurses in teaching women to examine their breasts themselves and in reminding them to perform the examination was emphasized.     

Does disparate occurrence of autoregulatory programmed frameshifting in decoding the release factor 2 gene reflect an ancient origin with loss in independent lineages?

In Escherichia coli an autoregulatory mechanism of programmed ribosomal frameshifting governs the level of polypeptide chain release factor 2. From an analysis of 20 sequences of genes encoding release factor 2, we infer that this frameshift mechanism was present in a common ancestor of a large group of bacteria and has subsequently been lost in three independent lineages.     

Application of computed X-ray tomography scanning in the study of thermo-oxidative degradation of thick-walled filled natural rubber vulcanizates

The aging of five thick-walled natural rubber compounds has been studied by computed X-ray tomography scanning and crosslink density measurements. The compounds were compouded as ordinary carbon-black-filled rubbers with sulfur and peroxide as curing agents. The rubber samples were aged in air at 70, 100, and 150°C for 1000h. The relatively new technique of computed X-ray tomography scanning proved to be a good method for studying the aging procedure, and especially for following the crack propagation in the surface. Antioxidants (TMQ and 6PPD) had a low effect on the resistance toward oxidative degradation and crosslinking under these conditions. Surprisingly, the efficient sulfur-vul-canized material had a poor resistance toward thermal degradation. When the crosslink density and the computed X-ray tomography scanning results were compared, it was assumed that the computed X-ray tomograph detected oxygen in the surface, both as elementary oxygen and as oxygen in degradation products, i.e., in carbonyls. The results agree well with the theory that oxidative aging is limited by the ability of the oxygen to diffuse into the material.     

Heparan/chondroitin/dermatan sulfate primer 2-(6-hydroxynaphthyl)-O-beta-D-xylopyranoside preferentially inhibits growth of transformed cells

Melanocortins are proopiomelanocortin-derived peptides that include adrenocorticotropic hormone [ACTH (1-39)], alpha-melanocyte-stimulating hormone [alpha-MSH (1-13)], and related amino acid sequences. Melanocortin peptides have potent antiinflammatory/anticytokine activity. Because cytokines such as interleukin 1 (IL-1) and tumor necrosis factor (TNF) can be detrimental in HIV-infected patients, we investigated the effects of melanocortins on production of IL-1 and TNF alpha in the blood of HIV patients. Cytokine production was measured in whole blood samples stimulated with LPS in the presence or absence of alpha-MSH (1-13), alpha-MSH (11-13), ACTH (1-24), or ACTH (1-39). Melanocortins reduced production of both cytokines in a concentration-dependent fashion. In separate experiments on normal peripheral blood mononuclear cells (PBMC), alpha-MSH (1-13) inhibited production of IL-1 beta and TNF alpha induced by HIV envelope glycoprotein gp 120. These results suggest that stimulation of melanocortin receptors in inflammatory cells could be a novel way to reduce production of cytokines that promote HIV replication.     

Numerical simulation of the wind shadow effect on the convective heat transfer to glass bulb sprinklers

A theoretical analysis of the wind shadow effect caused by the arms of the sprinkler frame has been performed using a finite volume computer code. The calculations show that the influence of the arms of the frame upon the convective heat transfer to the bulb is small when the arms of the sprinkler frame and the bulb are orientated perpendicular to the flow. The arms of the frame cause a slight acceleration of the flow around the bulb. Hence, the heat transfer to the bulb in this orientation is somewhat greater than for free flow around a cylinder. In the case when the arms of the sprinkler frame are aligned with the flow, the heat transfer is decreased by approximately a factor of two for the particular geometry considered. This is in agreement with results from wind-tunnel tests for the same geometry. The Nusselt number for this case is still roughly proportional to the square root of the Reynolds number. This finding is of practical importance, as the lumped mass theory for calculating the time to operation of sprinklers relies heavily on the assumption of a square root dependence of the Reynolds number. Good agreement is found between calculated and measured velocity profiles in the region between the glass bulb and the upstream arm of the frame, when the arms are aligned with the airflow.