Material properties and full-scale rain exposure of lime-hemp concrete walls

Lime-hemp concrete (LHC) is a building material consisting of a lime-based binder combined with hemp shiv that is suitable for various building applications. This thesis aimed to elucidate the possibilities for using LHC for exterior walls in a cold, wet climate through investigating mechanical, thermal and moisture-related properties of the material. The mechanical properties of LHC containing both shiv and fibres of the hemp stalk in combination with different binders were tested in order to find a mixture with increased mechanical strength so that a supporting timber load-bearing structure could be omitted. A larger amount of cement in the binder mix improved compressive strength. However, even when using unseparated hemp (both shiv and fibres) in combination with a high-cement binder, mechanical strength was not sufficient for the material to be load-bearing without additional support. The moisture properties of LHC were studied in order to determine its robustness and durability in cold, wet conditions. Sorption isotherms and moisture diffusivity were determined over the complete moisture range for two LHC mixes with different lime:hemp ratios. Compared with other building materials (e.g. timber, cellular concrete and lime-based render), LHC showed a high moisture diffusion coefficient in the 35-95% relative humidity (RH) range. The sorption isotherm of LHC appeared quite planar up to 95% RH, but steep between 95 and 100% RH. The thermal properties of specimens with different relative humidities were found to be influenced by RH. At higher RH values thermal conductivity was higher, whereas differences in thermal diffusivity and specific heat capacity as a consequence of differences in RH were less apparent. Four full-scale wall sections combining different renders and LHC mixes were exposed to a rain scenario in order to fully understand the hygric performance. Moisture properties were used in computer simulations of these full-scale wall sections and the simulation results compared with measured data. It was found that even after prolonged rain exposure, some wall sections had low moisture levels inside the wall. A lime-cement render allowed rain to penetrate the wall more easily than a cement render and also dried more slowly after exposure to rain. LHC with a larger proportion of hemp absorbed moisture more slowly and dried more quickly after construction than a mix with a larger proportion of lime. This indicates that LHC with more hemp in the mix in combination with a cement render would be more suitable for use in a cold, wet climate

CD26-negative and CD26-positive tissue-resident fibroblasts contribute to functionally distinct CAF subpopulations in breast cancer

The origin of cancer-associated fibroblasts (CAFs) in cancer remains to be identified. Here, single-cell transcriptomics, in vivo and in vitro studies suggest that CD26+ and CD26- normal fibroblasts transform into distinct CAF subpopulations in mouse models of breast cancer

Complex Odor from Plants under Attack: Herbivore's Enemies React to the Whole, Not Its Parts

Background: Insect herbivory induces plant odors that attract herbivores ’ natural enemies. Assuming this attraction emerges from individual compounds, genetic control over odor emission of crops may provide a rationale for manipulating the distribution of predators used for pest control. However, studies on odor perception in vertebrates and invertebrates suggest that olfactory information processing of mixtures results in odor percepts that are a synthetic whole and not a set of components that could function as recognizable individual attractants. Here, we ask if predators respond to herbivoreinduced attractants in odor mixtures or to odor mixture as a whole. Methodology/Principal Findings: We studied a system consisting of Lima bean, the herbivorous mite Tetranychus urticae and the predatory mite Phytoseiulus persimilis. We found that four herbivore-induced bean volatiles are not attractive in pure form while a fifth, methyl salicylate (MeSA), is. Several reduced mixtures deficient in one component compared to the full spider-mite induced blend were not attractive despite the presence of MeSA indicating that the predators cannot detect this component in these odor mixtures. A mixture of all five HIPV is most attractive, when offered together with the noninduced odor of Lima bean. Odors that elicit no response in their pure form were essential components of the attractive mixture. Conclusions/Significance: We conclude that the predatory mites perceive odors as a synthetic whole and that th

Publisher Correction: Truncated FGFR2 is a clinically actionable oncogene in multiple cancers.

This paper was originally published under a standard Springer Nature license

Hemp concretes

Hemp (Cannabis sativa) is an agricultural crop that can be used as a building material in combination with lime and cement. A composite building material that combines a cementitious binder (building limes and cement) with hemp shives, the woody core of the hemp stalk is generally referred to as hemp concrete (HC). However, industrial facilities to separate hemp shives and fibres are currently not available in Sweden. HC has many advantages as a building material but it is not load-bearing and must be used in combination with a load-bearing wooden frame. The aim of this research was to elucidate the feasibility of using both hemp shives and fibres in a HC to determine an optimal mix of the different binding agents and to investigate if adding undensified microsilica to the mix and using calcinated gypsum as a binder would improve mechanical strength of the material. The effects on compressive strength of pre-mixing the binder or creating perforations in the test specimens were also investigated. Cube and cylinder specimens cured for 40 days in a carbonation room (4.5 vol% CO2) were tested for mechanical properties, water sorption and frost resistance. Including more hydraulic lime or undensified microsilica in the mix did not significantly affect mechanical strength, whereas adding more cement to the mix increased mechanical strength. Calcinated gypsum as a binder gave mechanical properties of the same magnitude of a contemporary HC. Pre-mixing the binder created a more homogeneous material but it did not seem to play an important role in final mechanical properties. The perforations created in some of the test specimens produced a material with a lower Young’s modulus and higher deformation at rupture. Using both shives and fibres in a hemp concrete may be a suitable approach in Sweden until facilities for separating hemp fibres from shives become available

Understanding Deterioration due to Salt and Ice Crystallization in Scandinavian Massive Brick Masonry

Extensive durability problems such as weathering and degradation are found in historic Scandinavian brick masonry buildings, especially from the neo-Gothic period. These are largely due to the crystallization of salts and frost action in the bricks and mortars. This article aims to show and illustrate which salts and crystals are found in historic brick masonry buildings and to describe their appearance and behavior. An additional aim is to explore possibilities of preventing salt-related damage on internal masonry wall surfaces, such as using hemp-lime sacrificial plaster beneath the plaster. The objective is to show the mechanisms behind salt-related problems and to perform a case study and a laboratory study on salt-damaged brick masonry containing sodium sulphate. In order to prevent and stop damage to the masonry, it is important to be able to identify the nature of the salt damage and the type of salt that caused the damage. Neo-Gothic brick masonry buildings require well-planned, continuous maintenance of the masonry. It is therefore of the utmost importance to have an understanding of the complex functions of the masonry and of the salts that can cause damage to these historic buildings

Full-scale Studies of Improving Energy Performance by Renovating Historic Swedish Timber Buildings with Hemp-lime

With an increased focus on reducing greenhouse gas emissions, energy saving is of great importance in all sectors of society. EU directives set targets for member states to reduce energy use in buildings. Energy saving in historic buildings requires special measures, balancing energy-saving renovations against the preservation of heritage values. Traditional constructions are open to vapor diffusion and generally work differently from modern constructions. Modern materials in traditional constructions sometimes damages the original material as they are usually diffusion-tight. The aim of this study was to investigate whether hemp-lime could be used as an insulation material to improve the energy efficiency of historic timber building envelopes with a rendered facade in Sweden. The objective was to determine the actual energy savings for space heating. An additional objective was to determine the actual thermal transmittance and to study thermal buffering through in-situ measurements in a full-scale wall renovated with hemp-lime. Two full-scale wall sections were constructed at the Energy and Building Design laboratory at Lund University: A traditional post-and-plank wall with a lime render (80 mm), and a post-and-plank wall with a hemp-lime render (90 mm). Energy use for space heating was monitored continuously over a period of one year. The wall with a hemp-lime render required 33% less energy for space heating than the traditional post-and-plank wall with a lime render. This was accomplished without changing the framework, appearance or material in the render and without drastically changing the hygric properties of the facade. From the gathered data, the thermal transmittance (U-values) for both walls was calculated using two different methods, one based on material properties and the other based on energy use data. For both walls, thermal transmittance based on actual energy use data during the heating period was lower than what was expected from their material properties. This indicates that more material properties than thermal conductivity and material thickness need to be taken into account when performing energy use calculations. With hemp-lime, a renovation can be accomplished without damaging the timber structure and wooden slats, and it can be done with local traditional materials and building methods with no difference in appearance to a traditional lime render. This allows for heritage values to be preserved, while also allowing the building to comply with modern standards and with increased thermal comfort and reduced energy use