A critical literature review of moisture and temperature conditions in wood exposed outdoors above ground

Summary In the majority of the field studies reviewed in this report samples were exposed outdoors above ground and only the average moisture content was determined. Therefore, no information is given about the moisture content in joints and other moisture traps. In many of the field studies, information on relative humidity, temperature, rainfalls etc. is missing and consequently these field studies cannot be used for relating the level of moisture content in the wood to the climate. Since the field studies are comparative studies it is, however, possible to summarise which parameters, wood properties and handling conditions, that do or do not affect the moisture uptake of wood. In some of the studies, factors affecting the growth of the tree are directly related to secondary wood properties such as the moisture uptake instead of to the primary wood properties such as density. The influence of different paint systems on the moisture content of wood has been widely studied. However, most studies only compare the effect of different paint systems or the impact of various end grain sealers. The impact of coating colour has also been studied. Few attempts have been made to study the impact of design on the moisture content. Most studies on this subject concern claddings. Studies on how duration of surface moisture is affected by design are also missing, as are studies relating climate to moisture content

Wild Boar : A Reservoir of Foodborne Zoonoses

Wild boar populations around the world have increased dramatically over past decades. Climate change, generating milder winters with less snow, may affect their spread into northern regions. Wild boars can serve as reservoirs for a number of bacteria, viruses, and parasites, which are transmissible to humans and domestic animals through direct interaction with wild boars, through contaminated food or indirectly through contaminated environment. Disease transmission between wild boars, domestic animals, and humans is an increasing threat to human and animal health, especially in areas with high wild boar densities. This article reviews important foodborne zoonoses, including bacterial diseases (brucellosis, salmonellosis, tuberculosis, and yersiniosis), parasitic diseases (toxoplasmosis and trichinellosis), and the viral hepatitis E. The focus is on the prevalence of these diseases and the causative microbes in wild boars. The role of wild boars in transmitting these pathogens to humans and livestock is also briefly discussed.Peer reviewe

A method for determination of absorption isotherms at high relative humidity levels: measurements on lime-silica brick and Norway spruce (Picea abies (L.) Karst.)

The relationship between the relative humidity and the moisture content of a material for relative humidity levels close to 100% can be studied using the pressure plate technique. However, this method is designed for desorption experiments and modifications are necessary in order to perform absorption experiments. This paper presents a method to condition samples to a uniform moisture content by absorption with the pressure plate technique. The specimens were suspended in magnetic clamps until the ceramic plate had equilibrated with the applied pressure and modifications were made so that water could circulate through the pressure plate cell

The states of water in Norway spruce (<i>Picea abies</i> (L.) Karst.) studied by low-field nuclear magnetic resonance (LFNMR) relaxometry:assignment of free-water populations based on quantitative wood anatomy

Low-field nuclear magnetic resonance (LFNMR) relaxometry was applied to determine the spin-spin relaxation time (T2) of water-saturated Norway spruce (Picea abies (L.) Karst.) specimens cut from mature sapwood (sW) and mature and juvenile heartwood (hW), where earlywood (EW) and latewood (LW) were separated. In combination with quantitative wood anatomy data focusing on the void volumes in various morphological regions, the NMR data served for a more reliable assignment of free-water populations found in water-saturated solid wood. Two free-water populations were identified within most sample types. One was assigned to water in the tracheid lumen and the other to water inside bordered pits. Whether water in the ray cell lumina was included in one or the other of these two populations depends on the curve-fit method applied (continuous or discrete). In addition, T2 differences between the different tissue types were studied and, for comparison, sorption isotherms were measured by means of a sorption balance. There was a significant difference between EW and LW as well as between juvenile wood and mature wood in terms of T2 related to the cell wall water. However, no differences were seen between the sorption isotherms, which indicates that the observed T2 differences were not due to differences in cell wall moisture content (MC)

Variation in the prevalence of enteropathogenic Yersinia in slaughter pigs from Belgium, Italy, and Spain

Tonsils of 829 fattening pigs originating from Belgium (n = 201), Italy (n = 428), and Spain (n 200) were collected between 2005 and 2007 to study the prevalence of enteropathogenic Yersinia in slaughter pigs. Isolation of Yersinia enterocolitica and Yersinia pseudotuberculosis was done by selective enrichment and by cold enrichment for 7 and 14 days. Pathogenic Y. enterocolitica and Y. pseudotuberculosis isolates were identified by polymerase chain reaction targeting the chromosomal genes ail and inv, respectively, as well as the plasmid-encoded virF of both species. A significantly higher (p < 0.001) prevalence of ail-positive Y. enterocolitica in Spain (93%) than in Belgium (44%) or Italy (32%) was observed. virF-positive Y. enterocolitica was present in 77% of ail-positive samples. Bioserotype 4/O:3 was the most common type in all three countries. Bioserotypes 2/O:5 and 3/O:9 were found in Italy (1%) and Belgium (9%), respectively. The prevalence of inv- and virF-positive Y. pseudotuberculosis was 2% and 1% in Belgium and Italy, respectively. Y. pseudotuberculosis was not detected in pigs from Spain. Bioserotypes 1/O:1 (20%), 1/O:2 (20%), and 2/O:3 (60%) were found in Belgium, and 1/O:1 (60%) and 2/O:3 (20%) in Italy. The most efficient method for isolation of Y. enterocolitica was combined cold enrichment for 7 and 14 days; however, the isolation method for Y. pseudotuberculosis was cold enrichment for 14 days. Fattening pigs seemto be an important reservoir of pathogenic Y. enterocolitica in Belgium, Italy, and Spain. Bioserotype 4/O:3 of Y. enterocolitica and bioserotypes 2/O:3 and 1/O:1 of Y. pseudotuberculosis have been shown to predominate

Moisture content prediction of rain-exposed wood: Test and evaluation of a simple numerical model for durability applications

Abstract in FrenchDecay-prediction models can be used to predict the service life of wooden components. However, knowledge of how the material climate, i.e. moisture content and material temperature, varies with time is required. A reliable material climate prediction model is therefore crucial in situations when measurements are not viable. The aim of this paper is to develop and assess the performance of a simple numerical moisture transport model for rain-exposed wood. The main focus is on the influence of rain and moisture transport in the transversal direction.First, a model based on Fick’s second law of diffusion was calibrated against laboratory measurements where wooden boards were exposed to artificial rain. Second, the model was tested against field-test measurements on wooden boards in use-class 3.1, i.e. above-ground, exposed to rain and free to dry. The influence of rain was investigated by studying the difference between sheltered and exposed specimens over time. Finally, the model was applied to a number of Swedish climates and two different decay-prediction models were used to assess the output.The main conclusion is that the influence of rain can be reproduced with sufficient accuracy for the particular application. The error between the numerical result and measurements tends to increase with decreasing temperature and at high moisture contents. However, the total error is reduced when the moisture content history is post-processed in a decay-prediction model as the rate of decay decreases with decreasing temperature

Psychrometer method to measure the moisture retention curves of porous building materials in the full humidity range

Moisture retention curves describe the moisture storage property of porous building materials. Currently available experimental methods for measuring moisture retention curves are often demanding in equipment and moreover not always suited for the adsorption process in most of the capillary moisture content range. This paper proposes a novel and simple technique – the psychrometer method – and validates it by the tests on calcium silicate and ceramic brick. In this experiment the moisture content of the samples experiencing adsorption and desorption processes is determined gravimetrically, while the corresponding capillary pressures in the samples are measured with a chilled-mirror dew-point psychrometer. Comparisons are made with results from mercury intrusion porosimetry, pressure plate/membrane and desiccator tests. It is shown that this psychrometer method is simple and reliable for both adsorption and desorption processes for capillary pressures below -1·105 Pa. When the capillary pressure is around or above -1·105 Pa, the psychrometer method is no longer very accurate, and other experimental techniques should be employed

Studying amount, location and state of water in modified wood at moisture levels relevant for fungal degradation

Water is an essential parameter for fungal degradation of wood, but degradation primarily occursat high moisture levels at water potential in the range of -4 to -0.1 MPa, which corresponds to 97-99.9% relative humidity. At these moisture levels, water is present in the wood structure both inand outside of cell walls. The majority of previous studies on the interaction between wood andwater for untreated as well as modified wood has, however, focused on the moisture range 0-95%relative humidity and mainly on water in cell walls. In this paper, we give examples of how preciseconditioning of specimens using the pressure plate technique can be combined with otherexperimental techniques in order to get information on interactions between wood and water athumidity levels relevant for fungal degradation. We show examples of how pressure plateconditioning can be combined with Differential Scanning Calorimetry (DSC) and Low FieldMagnetic Resonance (LFNMR) to get information not only about amount of water, but also aboutlocation and state of water in untreated and modified wood. Further use of such combination oftechniques has potential to give valuable pieces of information on the role of water in degradationprocesses for untreated as well as modified wood

Comparison of commercial ELISA tests for the detection of Toxoplasma antibodies in the meat juice of naturally infected pigs

Toxoplasmosis is a globally distributed protozoal zoonosis. Pigs are considered an important reservoir of Toxoplasma gondii and pork a major infection source of human toxoplasmosis. ELISA methods are commonly used diagnostic tools for detecting Toxoplasma infections. They are also used for slaughterhouse-based serological monitoring of toxoplasmosis in pigs to identify positive farms. The methods used are non-standardised with varying sensitivity and specificity. In our study, four commercial ELISA tests for the detection of Toxoplasma antibodies in the meat juice of slaughter pigs were compared with a modified agglutination test (MAT) as a reference. The cut-off values of the ELISA tests provided by the manufacturer varied between 0.20 and 0.50, and clearly influenced prevalence. The sensitivity of tests I, II and III varied between 96.4 and 78.6. Sensitivity was unacceptably low (3.6) for test IV (cut-off=0.30). Tests I, II and III had the highest accuracy and the best agreement with the reference test when a cut-off of 0.30 was used. Test II and III showed very good agreement (K=0.92 and 0.84, respectively) with the MAT. A very strong correlation (Pearson correlation >0.89) was observed between the S/P values of tests I, II and III. Our results demonstrate that the test and cut-off value used influence the results of the apparent seroprevalence studies. (C) 2017 Elsevier B.V. All rights reserved.Peer reviewe