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The CO2 emission rates have been continuously incremented during the last decades. To mitigate it, a method to store carbon in terrestrial ecosystems is the addition of biochar to soil. After its application to soil, biochar suffers an ageing process, able to deteriorate its functional properties as soil improver. However, at present, it is not clear how to evaluate biochar ageing. The main aim of this study is to evaluate biochar ageing by determination of temporal changes on (a) soil respiration after biochar addition and (b) the relationship between CO2 adsorption capacity and wettability of biochar as measurable parameters indicating biochar ageing. Results show that 1 month after biochar addition, soil respiration decreased when poplar and pine biochars were applied to bare soils, in the absence of vegetation. One year after biochar addition, this reduction on soil respiration disappeared, evidencing biochar ageing due to decrements on its CO2 adsorption capacity. Compared with fresh biochar, decreased CO2 adsorption capacity of biochar corresponded with enhanced biochar wettability for both biochar types. Its means that poplar and pine biochars, while initially hydrophobic, became hydrophilic after 1 year of its application to soil. It is concluded that changes of biochar CO2 adsorption capacity in time go along with improved wettability as mutually opposed processes. Globally, pine biochar tends to adsorb a higher quantity of CO2 than poplar biochar. The absence of CO2 adsorption of soil without biochar demonstrates the remarkable capacity of both biochars to adsorb carbon dioxide and promote carbon storage in soils. [ABSTRACT FROM AUTHOR]

The influence of a buffer layer in the surface of a Cu(In,Ga)Se2 (CIGS) solar cell material is studied using implanted positive muons as a probe. A depth resolved analysis of the muon data suggests that both CdS and ZnSnO reduce the width of a defect layer present at the CIGS surface to about half its original value. Additionaly, CdS is able to reduce the intensity of the distur¬bance in the defected region, possibly due to a surface reconstrution in CIGS.

We identified in this experiment two muon configurations in Lu2O3, the oxygen-bound (O-Mu+) ground state and a metastable (energy barrier 0.7(3) eV) atom-like excited state. These configurations are partially not formed immediately after implantation but somewhat delayed due to the requirement of a lattice rearrangement around the muon. These rearrangement processes occur on a timescale of ns to µs and are thus observable in µSR experiments. A special role plays a fairly long-lived (ns to µs) transition state as an intermediate step in the reaction process.

Sensitive, selective, low-cost, and simply designed sensors for gases and analytes are highly attractive. The rational synergy between calixarenes (CAs) and titania nanorods (TiO2NRs) and nanotubes (TiO2NTs) gives rise to completely new types of behaviors that open unprecedented applications. First, the geometric building of NRs and NTs leads to excellent signal amplification and transduction. Second, grafted CAs create self-assembled monolayers (SAMs) that switch order under a thermal stimulus and generate a stimuli-responsive behavior, thus promoting modulated sensing properties. Third, CAs accelerate gas diffusion in the sensor, yielding a fast, sensitive, selective, and reproducible response to H2 at room temperature (RT). In addition, these systems may act as sensors for other analytes, such as the pesticide profenofos (PFF). [ABSTRACT FROM AUTHOR]

This paper shows how wideband and directional channel physical constraints fundamentally condition adaptive beamforming, comparing between micro- and macro-cells. We define the angular and temporal densities, and multiuser multipath frequency parameters. Their meaning roots from the way that temporal and angular dispersions affect the original correlation properties of signals transmitted among links, reflecting channel richness in the multiuser sense. Their trends are consistent with beamforming performance divergences between those cell environments, helping to establish the main physical constraints. Among key micro- and macro-cell multiuser propagation scenarios, multiuser multipath frequency values are near one order of magnitude larger in micro-cells, compared to macro-cells. This is in agreement with the better beamforming obtained for the micro-cells channel. In the case of terminal grouping, where multiuser channels contribute with the same angles- and times-of-arrival, beamforming gains are limited to being close to 0 dB in macro-cells. In similar conditions, micro-cells' results reach up to 11.6 dB for 4 users, or 9.6 dB for 16, and also render larger beamforming robustness. The physical-level reasoning behind this work is flexible to be applied to most wideband directional propagation models. The presented parameters are general and useful in evaluating spatial filtering techniques, together with those models. [ABSTRACT FROM AUTHOR]

Abstract: In this Letter we describe the synthesis and characterization of a new multiporous crystalline framework based on meso-tetra-(2-quinolyl)-porphyrin, that presents crystal channels adequate for CO2 reversible sequestering, from 1 to 5bar of CO2 pressures. This behaviour is very different from the parent meso-tetraphenyl-porphyrin, which points to an important favourable interaction of CO2 with meso-substituted nitrogen aromatic porphyrin free bases. [Copyright &y& Elsevier]