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Thermoelectrics, in particular solid-state conversion of heat to electricity, is expected to be a key energy harvesting technology to power ubiquitous sensors and wearable devices in the future. A comprehensive review is given on the principles and advances in the development of thermoelectric materials suitable for energy harvesting power generation, ranging from organic and hybrid organic-inorganic to inorganic materials. Examples of design and applications are also presented.

Sorption isotherms describe the relation between the equilibrium moisture content of a material and the ambient relative humidity. Most materials exhibits sorption hysteresis, that is, desorption give higher equilibrium moisture contents than absorption at equal ambient climate conditions. Sorption hysteresis is commonly evaluated by determination of an absorption isotherm followed by desorption starting from the highest relative humidity used in the absorption measurement (typically 95%). The latter is often interpreted as the desorption isotherm but is in fact a scanning isotherm, i.e. an isotherm obtained from neither dry nor water-saturated state. In the present study, we investigated the difference between desorption isotherms and scanning isotherms determined by desorption from different high relative humidity levels reached by absorption and how this difference influenced the evaluation of sorption hysteresis. The measurements were performed on Norway spruce ( Picea abies (L.) Karst.) using automated sorption balances. Hysteresis evaluated from desorption isotherms gave linear absolute sorption hysteresis for the studied relative humidity range (0–96%), whereas hysteresis evaluated from scanning isotherms gave non-linear curves with a peak between 50 and 80% relative humidity. The position of this peak depended on the relative humidity from which desorption was initiated. Consequently, understanding and evaluation of sorption hysteresis might be challenging if scanning isotherms are used instead of desorption isotherms, hereby increasing the risk of misinterpreting the results. Graphical Abstract

Materials with heterogeneous microstructures architected across several scales are becoming increasingly popular in structural applications due to unique strength–ductility balance. One of the most popular 3D-architected structure designs is harmonic structure (HS) where soft coarse-grain (CG) islands are embedded in a hard continuous 3D skeleton of ultrafine grains (UFGs). In this work, a series of HS with varying phase fractions and rheologies are studied based on several models. Model A focuses on a good fit with experimental data in the elastic–plastic transition region, model B focuses on a good fit at large-scale yielding, while in five intermediate models, phase rheology parameters are varied on a linear scale between the values for A and B. For each of the seven selected HS material models, structures with 19 different volumetric fractions of UFG were examined. It is found that the increase of UFG fraction leads to the monotonic increase of strength characteristics in HS material, while higher strain hardening rates in the phases lead to the enhancement of this effect. By contrast, the dependence of ductility characteristics on UFG fraction is non-monotonic having a local minimum at 30% UFG and a maximum at 60% UFG, while also significantly dependent on strain hardening in the phases. Namely, HS material with phases having significant strain hardening reveals the highest uniform elongation exceeding that in 100% CG material already at 40% UFG fraction. The fractions of UFG in a range of 58–62% form HS material with the highest possible uniform elongation.

Titan aluminium alloys belong to the group of α – β -alloys, which are used for many applications in industry due to their advantageous mechanical properties, e.g. for laser powder bed fusion (PBF-LB) processes. However, the composition of the crystal structure and the respective magnitude of the solid fraction highly influences the material properties of titan aluminium alloys. Specifically, the thermal history, i.e. the cooling rate, determines the phase composition and microstructure for example during heat treatment and PBF-LB processes. For that reason, the present work introduces a phase transformation framework based, amongst others, on energy densities and thermodynamically consistent evolution equations, which is able to capture the different material compositions resulting from cooling and heating rates. The evolution of the underlying phases is governed by a specifically designed dissipation function, the coefficients of which are determined by a parameter identification process based on available continuous cooling temperature (CCT) diagrams. In order to calibrate the model and its preparation for further applications such as the simulation of additive manufacturing processes, these CCT diagrams are computationally reconstructed. In contrast to empirical formulations, the developed thermodynamically consistent and physically sound model can straightforwardly be extended to further phase fractions and different materials. With this formulation, it is possible to predict not only the microstructure evolution during processes with high temperature gradients, as occurring in e.g. PBF-LB processes, but also the evolving strains during and at the end of the process.

Wood is a hygroscopic material that absorbs and desorbs water to equilibrate to the ambient climate. Within material science, the moisture range from 0 to about 95–98% relative humidity is generally called the hygroscopic moisture range, while the exceeding moisture range is called the over-hygroscopic moisture range. For wood, the dominating mechanisms of moisture sorption are different in these two moisture ranges; in the hygroscopic range, water is primarily bound by hydrogen bonding in cell walls, and, in the over-hygroscopic range, water uptake mainly occurs via capillary condensation outside cell walls in macro voids such as cell lumina and pit chambers. Since large volumes of water can be taken up here, the moisture content in the over-hygroscopic range increases extensively in a very narrow relative humidity range. The over-hygroscopic range is particularly relevant for durability applications since fungal degradation occurs primarily in this moisture range. This review describes the mechanisms behind moisture sorption in the over-hygroscopic moisture range, methods that can be used to study the interactions between wood and water at these high humidity levels, and the current state of knowledge on interactions between modified wood and water. A lack of studies on interactions between modified wood and water in the over-hygroscopic range was identified, and the possibility of combining different methods to acquire information on amount, state, and location of water in modified wood at several well-defined high moisture states was pointed out. Since water potential is an important parameter for fungal growth, such studies could possibly give important clues concerning the mechanisms behind the increased resistance to degradation obtained by wood modification.

Wood is a porous, hygroscopic material with engineering properties that depend significantly on the amount of water (moisture) in the material. Water in wood can be present in both cell walls and the porous void-structure of the material, but it is only water in cell walls that affects the engineering properties. An important characteristic of wood is therefore the capacity for water of its solid cell walls, i.e. the maximum cell wall moisture content. However, this quantity is not straight-forward to determine experimentally, and the measured value may depend on the experimental technique used. In this study, we used a triangulation approach to determine the maximum cell wall moisture content by using three experimental techniques based on different measurement principles: low-field nuclear magnetic resonance (LFNMR) relaxometry, differential scanning calorimetry (DSC), and the solute exclusion technique (SET). The LFNMR data were furthermore analysed by two varieties of exponential decay analysis. These techniques were used to determine the maximum cell wall moisture contents of nine different wood species, covering a wide range of densities. The results from statistical analysis showed that LFNMR yielded lower cell wall moisture contents than DSC and SET, which were fairly similar. Both of the latter methods include factors that could either under-estimate or over-estimate the measured cell wall moisture content. Because of this and the fact that the DSC and SET methods are based on different measurement principles, it is likely that they provide realistic values of the cell wall moisture content in the water-saturated state.

We investigate the bottom-up growth of N = 7 armchair graphene nanoribbons (7-AGNRs) from the 10,10′-dibromo-9,9′-bianthracene (DBBA) molecules on Ag(111) with the focus on the role of the organometallic (OM) intermediates. It is demonstrated that DBBA molecules on Ag(111) are partially debrominated at room temperature and lose all bromine atoms at elevated temperatures. Similar to DBBA on Cu(111), debrominated molecules form OM chains on Ag(111). Nevertheless, in contrast with the Cu(111) substrate, formation of polyanthracene chains from OM intermediates via an Ullmann-type reaction is feasible on Ag(111). Cleavage of C–Ag bonds occurs before the thermal threshold for the surface-catalyzed activation of C–H bonds on Ag(111) is reached, while on Cu(111) activation of C–H bonds occurs in parallel with the cleavage of the stronger C–Cu bonds. Consequently, while OM intermediates obstruct the Ullmann reaction between DBBA molecules on the Cu(111) substrate, they are required for the formation of polyanthracene chains on Ag(111). If the Ullmann-type reaction on Ag(111) is inhibited, heating of the OM chains produces nanographenes instead. Heating of the polyanthracene chains produces 7-AGNRs, while heating of nanographenes causes the formation of the disordered structures with the possible admixture of short GNRs.

To investigate the effects of changes in biopolymer composition on moisture in acetylated poplar wood (Populus euramericana Cv.), the acetylation of control wood was compared to the acetylation of wood with reduced hemicellulose or lignin content (about 9% reduction of total specimen dry weight in both cases). Time-domain nuclear magnetic resonance relaxometry of water-saturated wood gave spin–spin relaxation times (T2) of water populations, while deuteration in a sorption balance was used to characterize the hydroxyl accessibility of the wood cell walls. As expected, the acetylation of pyridine-swelled wood reduced hydroxyl accessibility and made the cell wall less accessible to water, resulting in a reduction of cell wall moisture content by about 24% compared with control wood. Hemicellulose loss per se increased the spin–spin relaxation time of cell wall water, while delignification had the opposite effect. The combined effect of hemicellulose removal and acetylation caused more than a 30% decrease of cell wall moisture content when compared with control wood. The acetylated and partially delignified wood cell walls contained higher cell wall moisture content than acetylated wood. An approximate theoretical calculation of hydroxyl accessibility for acetylated wood was in the low range, but it agreed rather well with the measured accessibility, while acetylated and partially hemicellulose-depleted and partially delignified wood for unknown reasons resulted in substantially lower hydroxyl accessibilities than the theoretical estimate.

A literature review comprising 163 publications published over a period of 26 years from 1992 to 2018 is presented in this paper. This review discusses the generation and recycling of construction and demolition waste (CDW) as well as its main uses as raw materials for the construction engineering sector. This review pays attention to the use of CDW aggregates for sand, pavements/roads, bricks, ceramics, cementitious materials, and concrete productions, as well its uses as eco-friendly materials for water decontamination. The physical-chemical and mechanical characteristics of recycled aggregates play an important role in their correctly chosen applications. The results found in this literature survey allow us to conclude that recycled aggregates from CDW can be successfully used to produce construction materials with quality comparable to those produced with natural aggregates. We concluded that the use of CDWs as raw materials for manufacturing new construction materials is technically feasible, economical, and constitutes an environmentally friendly approach for a future construction and demolition waste management strategy.

Glass is largely used in architectural and engineering applications (i.e., buildings and vehicles) as a structural material, especially in the form of laminated glass (LG) sections. To achieve adequate and controlled safety levels in these applications, the well-known temperature-dependent behavior of viscoelastic interlayers for LG sections should be properly accounted for during the design process. Furthermore, the materials’ thermomechanical degradation with increases of temperature could severely affect the load-bearing performance of glass assemblies. In this context, uncoupled thermomechanical finite element (FE) numerical models could represent a robust tool and support for design engineers. Key input parameters and possible limits of the FE method, however, should be properly calibrated and assessed, so as to enable reliable estimations for the real behavior of glazing systems. In this paper, FE simulations are proposed for monolithic (MG) and LG specimens under radiant heating, based on one-dimensional (1D) and two-dimensional (2D) models. A special attention is focused on thermal effects, being representative of the first step for conventional uncoupled, thermomechanical analyses. Based on experimental results available in the literature, FE parametric studies are discussed, giving evidence of limits and issues due to several modeling assumptions. In particular, careful consideration is paid for various thermal material properties (conductivity, specific heat) and thermal boundaries (conductivity, emissivity), but also for other influencing parameters like the geometrical features of samples (thickness tolerances, cross-sectional properties, etc.), the composition of LG sections (interlayer type, thickness), the loading pattern (heat transfer distribution) and the presence of additional mechanical restraints (i.e., supports of different materials). Comparative FE results are hence critically discussed, highlighting the major effects of such influencing parameters.