Synthesis of new lead-containing MAX phases of Zr3PbC2 and Hf3PbC2

In this work, two new 312 MAX phases of Zr₃PbC₂ and Hf₃PbC₂ were successfully synthesized by spark plasma sintering. It is the first discovery of lead-containing 312 MAX phases, which together with M₂PbC (M = Ti, Zr, Hf) form the lead-containing MAX phase family. Considering the extremely low electrical conductivity of Hf₂PbC, these two new compounds are of great research value. Based on the Rietveld refinement results, their lattice parameters and atomic positions were well determined, as a = 3.3771(5) Å, c = 20.0070(9) Å for Zr₃PbC₂ and a = 3.3357(1) Å, c = 19.7659(8) Å for Hf₃PbC₂, where M atoms are located at (0, 0, 0) and (1/3, 2/3, 0.1258(6)[Zr]; 0.1255(2)[Hf]), Pb atoms are located at (0, 0, 1/4), and C atoms are located at (1/3, 2/3, 0.0663(2)[Zr]; 0.0641(3)[Hf]), respectively. Additionally, the typical laminar microstructure of Zr₃PbC₂ and Hf₃PbC₂ grains was observed.     

Pushing the Boundaries of Structural Heterogeneity with the Lipid A of Marine Bacteria Cellulophaga

Marine bacteria, which are often described as chemical gold, are considered an exceptional source of new therapeutics. Considerable research interest has been given to lipopolysaccharides (LPSs), the main components of the Gram-negative outer membrane. LPS and its lipid A portion from marine bacteria are known to exhibit a tricky chemistry that has been often associated with intriguing properties such as behaving as immune adjuvants or anti-sepsis molecules. In this scenario, we report the structural determination of the lipid A from three marine bacteria within the Cellulophaga genus, which showed to produce an extremely heterogenous blend of tetra- to hexa-acylated lipid A species, mostly carrying one phosphate and one D-mannose on the glucosamine disaccharide backbone. The ability of the three LPSs in activating TLR4 signaling revealed a weaker immunopotential by C. baltica NNO 15840^T and C. tyrosinoxydans EM41^T, while C. algicola ACAM 630^T behaved as a more potent TLR4 activator.     

Numerical Investigation of Perovskite and u-CIGS Based Tandem Solar Cells Using Silvaco TCAD Simulation

Silicon - In this paper, a numerical model is designed to evaluate the performances of a two-terminal tandem Perovskite-CIGS solar cell. Tandem perovskite solar cells (TPSCs) are a type of device...     

COLTHPF,a run-time support for the high-level co-ordination of HPF tasks

This paper describes COLT_HPF, a run-time support specifically designed for the co-ordination of concurrent and communicating HPF tasks. COLT_HPF is implemented on top of MPI and requires only small changes to the run-time support of the HPF compiler used. Although the COLT_HPF API can be used directly by programmers to write applications as a flat collection of interacting data-parallel tasks, we believe that it can be used more productively through a compiler of a simple high-level co-ordination language which facilitates programmers in structuring a set of data-parallel HPF tasks according to common forms of task-parallelism. The paper outlines design and implementation issues, and discusses the main differences from other approaches to exploiting task parallelism in the HPF framework. We show how COLT_HPF can be used to implement common forms of parallelism, e.g. pipeline and processor farms, and we present experimental results regarding both synthetic micro-benchmarks and sample applications. The experiments were conducted on an SGI/Cray T3E using Adaptor, a public domain HPF compiler. Copyright © 1999 John Wiley & Sons, Ltd.     

Spin-Orbit Readout Using Thin Films of Topological Insulator Sb2Te3 Deposited by Industrial Magnetron Sputtering

Driving a spin-logic circuit requires the production of a large output signal by spin-charge interconversion in spin-orbit readout devices. This should be possible by using topological insulators, which are known for their high spin-charge interconversion efficiency. However, high-quality topological insulators have so far only been obtained on a small scale, or with large scale deposition techniques that are not compatible with conventional industrial deposition processes. The nanopatterning and electrical spin injection into these materials have also proven difficult due to their fragile structure and low spin conductance. The fabrication of a spin-orbit readout device from the topological insulator Sb₂Te₃ deposited by large-scale industrial magnetron sputtering on SiO₂ is presented. Despite a modification of the Sb₂Te₃ layer structural properties during the device nanofabrication, a sizeable output voltage is measured that can be unambiguously ascribed to a spin-charge interconversion process. The results pave the way for the integration of layered van der Waals materials in spin-logic devices.     

Far from equilibrium ultrafast high-temperature sintering of ZrO2–SiO2 nanocrystalline glass–ceramics

Ultrafast high-temperature sintering (UHS) is a novel sintering technique with ultrashort firing cycles (e.g., a few tens of seconds). The feasibility of UHS has been validated on several ceramics and metals; however, its potential in consolidating glass–ceramics has not yet been demonstrated. In this work, an optimized carbon-free UHS was utilized to prepare ZrO₂–SiO₂ nanocrystalline glass–ceramics (NCGCs). The phase composition, grain size, densification behavior, and microstructures of NCGCs prepared by UHS were investigated and compared with those of samples sintered by pressureless sintering. Results showed that NCGCs with a high relative density (～95%) can be obtained within ～50 s discharge time by UHS. The UHS processing not only hindered the formation of ZrSiO₄ and cristobalite but also enhanced the stabilization of t-ZrO₂. Meanwhile, owing to the ultrashort firing cycles, the UHS technology allowed the NCGCs to be consolidated in a far from equilibrium state. The NCGCs showed a microstructure of spherical monocrystalline ZrO₂ nanocrystallites embedded in an amorphous SiO₂ matrix.