Flow patterns and thermal comfort in a room with panel,floor and wall heating

Thermal comfort aspects in a room vary with different space heating methods. The main focus in this study was how different heating systems and their position affect the indoor climate in an exhaust-ventilated office under Swedish winter conditions. The heat emitters used were a high and a medium–high temperature radiator, a floor heating system and large wall heating surfaces at low temperature. Computational fluid dynamics (CFD) simulations were used to investigate possible cold draught problems, differences in vertical temperature gradients, air speed levels and energy consumption. Two office rooms with different ventilation systems and heating needs were evaluated. Both systems had high air exchange rates and cold infiltration air.     

Influence of Fungal Infection and Wounding on Contents and Enantiomeric Compositions of Monoterpenes in Phloem of Pinus sylvestris

To identify chemical resistant markers induced by fungal or mechanical injury, young trees of Scots pine (Pinus sylvestris) were subjected to inoculations of blue stain fungi associated with the pine shoot beetles Tomicus piniperda and T. minor. Among the 20 trees selected for chemical analyses, 16 were divided into four groups: one as control and three were pretreated by wounding only, or by inoculation with either the blue stain fungus Leptographium wingfieldii or Ophiostoma canum. Four wk after pretreatment, all 16 pretreated trees were mass-inoculated with L. wingfieldii. The absolute and relative amounts, as well as the enantiomeric compositions of monoterpene hydrocarbons in the phloem, were determined via a small sample of the phloem before and after the pretreatment and mass inoculation, by using two-dimensional gas chromatography (2D GC) and GC-mass spectrometry (MS). After mass inoculation, the absolute amounts of most of the monoterpenes decreased in the phloem sampled >20 cm from the fungal infection, and were higher in the phloem sampled within the infected reaction zone. The relative amounts of both (−)-β-pinene and (−)-limonene increased in phloem samples taken >20 cm above the fungal inoculation in the preinoculated trees compared with phloem sampled from the remaining four control trees. The enantiomeric compositions of β-pinene and limonene changed, after fungal growth, at defined distances from the inoculation site: the proportion of the (−)-enantiomers was highest in the phloem sampled >20 cm from the fungal inoculation. Four wk after pretreatment, monoterpene production in the phloem at the site of inoculation was more enhanced by L. wingfieldii than by O. canum. However, the different virulence levels of the fungi did not affect the enantiomeric composition of the monoterpenes. The biosynthesis of monoterpene enantiomers is discussed in relation to induced pathogen resistance.     

Filiform corrosion of aluminium sheet. iii. microstructure of reactive surfaces

Metal surface properties, which induce susceptibility to filiform corrosion (FFC) of certain impure aluminium alloys by high temperature annealing, were investigated by analytical transmission electron microscopy (TEM). Analysis of cross-sectional foils revealed grain refined surface layers (GRSLs), approximately 1 mm thick on the rolled sheet, consisting of subgrains in the size range 20 to 200 nm. This layer was electrochemically more active than the bulk of the metal, and it was preferentially attacked by FFC of the painted substrate. By cold-rolling, a GRSL was also formed; however, such a layer did not cause surface activation and FFC. Annealing the etched surface not covered by a GRSL also activated the surface, indicating, together with the behaviour of cold-rolled surfaces, that GRSLs alone were not responsible for the surface activity. The analytical techniques employed were not able to detect any chemical modification of the surface which could explain the high surface reactivity. Possible mechanisms for the formation of reactive surface layers and the GRSLs are discussed. An obvious measure for avoiding FFC on painted aluminium sheet is to remove the active layer by etching or other chemical treatments prior to application of coating.     

Release and characterization of single side chains of white cabbage pectin and their complement‐fixing activity

A mixture of single side chains from white cabbage pectin were obtained by anion exchange chromatography after applying mild chemical conditions promoting β‐elimination. These pectin fragments were characterized by their molecular weight distribution, sugar composition, ¹³C‐NMR, and MALDI‐TOF‐MS analysis. These analyses revealed that the large oligosaccharides released by β‐eliminative treatment were composed of α‐1,5 linked arabinosyl residues with 2‐ and 3‐linked α‐arabinosyl side chains, and, or β‐1,4 linked galactosyl side chains. Fractions were tested for complement‐fixing activity in order to determine their interaction with the complement system. These results strongly indicated that there was a minimal unit size responsible for the complement‐fixing activity. Neutral pectin fragments (?8 kDa) obtained from β‐elimination were inactive in the complement system, although they contained a sugar composition previously shown to be highly active. Larger pectin fragments (?17 kDa) retained some activity, but much lower than polymers containing rhamnogalacturonan type 1 (RGI) structures isolated from the same source. This implied that structural elements containing multiple side chains is necessary for efficient complement‐fixing activity.     

Effect of thermomechanical history on intergranular corrosion of extruded AlMgSi(Cu) model alloy

The effect of cooling rate after extrusion, solution heat treatment, mechanical deformation and aging on intergranular corrosion (IGC) of two model AlMgSi alloys with different Cu content was investigated using an accelerated corrosion test. The low Cu extrusions (0.02 wt%) were resistant to IGC while the high Cu (0.17 wt%) variants were susceptible in certain tempers. Slow cooling in air introduced IGC. The IGC susceptibility was reduced and finally removed by artificial aging. Water quenching prevented IGC, but severe IGC was introduced by slight aging (underaging). Peak aging (T6) generally reduced IGC susceptibility regardless of cooling media. Overaging further reduced IGC, usually at the expense of introducing pitting. IGC susceptibility was related to the microgalvanic coupling between enriched Cu on the grain boundaries (noble) and the adjacent solute depleted zone (active). Cu enrichment was caused either by slow cooling in air or slight aging of water quenched samples. High IGC resistance was obtained either by keeping the Cu content low or by applying proper heat treatment to high Cu samples. For the present high Cu samples, artificial aging to peak strength provided at the same time the necessary IGC resistance.