Wet-chemical synthesis of enhanced-thermopower Bi1-xSbx nanowire composites for solid-state active cooling of electronics

In 1993, Hicks and Dresselhaus [Thermoelectric figure of merit of a one-dimensional conductor, Phys. Rev. B 47, 16631 (1993).] suggested that Bi nanowires could result in values of the thermoelectric figure of merit zT > 1. The Dresselhaus group also calculated a ternary phase diagram for Bi1-xSbx nanowires as a function of x and wire diameter. This manuscript reports a wet-chemical method to synthesize Bi1-xSbx-silica nanowire composites. Resistivity, Hall electron concentration, electron mobility, Seebeck and Nernst coefficients, and thermal conductivity of composites are measured and compared to bulk polycrystalline Bi1-xSbx samples prepared either by ingot casting or by the same wet chemistry but without nanostructuring. A clear increase of the thermopower in 20-nm Bi94Sb6-silica is reported when compared to bulk samples, and the values are among the highest found in the literature from 300 to 380 K, even though the electron concentration is higher than in the bulk. This suggests that consistent with theory, size quantization is responsible for the thermopower increase

Similarity solutions for unsteady shear-stress-driven flow of Newtonian and power-law fluids : slender rivulets and dry patches

Unsteady flow of a thin film of a Newtonian fluid or a non-Newtonian power-law fluid with power-law index N driven by a constant shear stress applied at the free surface, on a plane inclined at an angle α to the horizontal, is considered. Unsteady similarity solutions representing flow of slender rivulets and flow around slender dry patches are obtained. Specifically, solutions are obtained for converging sessile rivulets (0 < α < π/2) and converging dry patches in a pendent film (π/2 < α < π), as well as for diverging pendent rivulets and diverging dry patches in a sessile film. These solutions predict that at any time t, the rivulet and dry patch widen or narrow according to |x|3/2, and the film thickens or thins according to |x|, where x denotes distance down the plane, and that at any station x, the rivulet and dry patch widen or narrow like |t|−1, and the film thickens or thins like |t|−1, independent of N

Carbon stable isotope analysis of cereal remains as a way to reconstruct water availability: preliminary results

Reconstructing past water availability, both as rainfall and irrigation, is important to answer questions about the way society reacts to climate and its changes and the role of irrigation in the development of social complexity. Carbon stable isotope analysis of archaeobotanical remains is a potentially valuable method for reconstructing water availability. To further define the relationship between water availability and plant carbon isotope composition and to set up baseline values for the Southern Levant, grains of experimentally grown barley and sorghum were studied. The cereal crops were grown at three stations under five different irrigation regimes in Jordan. Results indicate that a positive but weak relationship exists between irrigation regime and total water input of barley grains, but no relationship was found for sorghum. The relationship for barley is site-specific and inter-annual variation was present at Deir ‘Alla, but not at Ramtha and Khirbet as-Samra

The reconciliation of fraternal twins: Integrating the psychological and sociological approaches to ‘micro’ corporate social responsibility

Aguinis and Glavas’ (2012) call for a deeper understanding of the microfoundations of corporate social responsibility (CSR) has spurred a growing number of empirical micro-CSR studies. Micro-CSR scholars share the common goal of developing a clear picture of the microfoundations of CSR—a holistic theoretical and empirical understanding of how individual actions and interactions drive CSR-related activity—but pursue this objective from a variety of angles. Our research suggests that although many scholars work under the same ‘micro-CSR’ banner, they approach their goal from a wide range of disciplines, use different methodologies, and study different phenomena. In this critical essay, we show that most micro-CSR research can be classified in one of two distinct sub-fields: ‘psychological micro-CSR’ and ‘sociological micro-CSR’. We compare the differences between these orientations (including their distinct empirical approaches, and contributions of both fields of micro-CSR) and explore possible opportunities for cross-fertilization between the psychological and sociological approaches. Finally, we suggest ways in which micro-CSR scholars could exploit the complementarities and eliminate the blind spots common to the two dominant micro-CSR approaches

Rectification of electronic heat current by a hybrid thermal diode

We report the realization of an ultra-efficient low-temperature hybrid heat current rectifier, thermal counterpart of the well-known electric diode. Our design is based on a tunnel junction between two different elements: a normal metal and a superconducting island. Electronic heat current asymmetry in the structure arises from large mismatch between the thermal properties of these two. We demonstrate experimentally temperature differences exceeding $60$ mK between the forward and reverse thermal bias configurations. Our device offers a remarkably large heat rectification ratio up to $\sim 140$ and allows its prompt implementation in true solid-state thermal nanocircuits and general-purpose electronic applications requiring energy harvesting or thermal management and isolation at the nanoscale.Comment: 8 pages, 6 color figure

A MESH TREE OPTIMIZER FOR WI-FI 8

Proposed herein is an artificial intelligence/machine learning (AIML) method to predict the goodput/throughout through a given mesh access point (MAP) for a wireless local area network (WLAN) that can be positioned at different possible spots in a mesh tree. The proposed method may communicate these predictions to MAPs and their clients, thus allowing the mesh tree to form (and reconfigure itself) into the most efficient structure. Further, the proposed method may allow clients to choose the MAP that will provide the best goodput/throughput for the mesh tree

WNT signalling in prostate cancer

Genome sequencing and gene expression analyses of prostate tumours have highlighted the potential importance of genetic and epigenetic changes observed in WNT signalling pathway components in prostate tumours-particularly in the development of castration-resistant prostate cancer. WNT signalling is also important in the prostate tumour microenvironment, in which WNT proteins secreted by the tumour stroma promote resistance to therapy, and in prostate cancer stem or progenitor cells, in which WNT-β-catenin signals promote self-renewal or expansion. Preclinical studies have demonstrated the potential of inhibitors that target WNT receptor complexes at the cell membrane or that block the interaction of β-catenin with lymphoid enhancer-binding factor 1 and the androgen receptor, in preventing prostate cancer progression. Some WNT signalling inhibitors are in phase I trials, but they have yet to be tested in patients with prostate cancer

Reassessment of the Lineage Fusion Hypothesis for the Origin of Double Membrane Bacteria

In 2009, James Lake introduced a new hypothesis in which reticulate phylogeny reconstruction is used to elucidate the origin of Gram-negative bacteria (Nature 460: 967–971). The presented data supported the Gram-negative bacteria originating from an ancient endosymbiosis between the Actinobacteria and Clostridia. His conclusion was based on a presence-absence analysis of protein families that divided all prokaryotes into five groups: Actinobacteria, Double Membrane bacteria (DM), Clostridia, Archaea and Bacilli. Of these five groups, the DM are by far the largest and most diverse group compared to the other groupings. While the fusion hypothesis for the origin of double membrane bacteria is enticing, we show that the signal supporting an ancient symbiosis is lost when the DM group is broken down into smaller subgroups. We conclude that the signal detected in James Lake's analysis in part results from a systematic artifact due to group size and diversity combined with low levels of horizontal gene transfer.Exobiology Program (U.S.) (Grant NNX08AQ10G)Assembling the Tree of Life (Program) (Grant DEB 0830024

Isolation of novel PSII-LHCII megacomplexes from pea plants characterized by a combination of proteomics and electron microscopy

This work was supported by the Italian Ministry of Education, University and Research, “Futuro in Ricerca 2013” program RBFR1334SB to CP