Strain-Induced Spin-Nematic State and Nematic Susceptibility Arising from 2×2 Fe Clusters in KFe_{0.8}Ag_{1.2}Te_{2}.

Spin nematics break spin-rotational symmetry while maintaining time-reversal symmetry, analogous to liquid crystal nematics that break spatial rotational symmetry while maintaining translational symmetry. Although several candidate spin nematics have been proposed, the identification and characterization of such a state remain challenging because the spin-nematic order parameter does not couple directly to experimental probes. KFe_{0.8}Ag_{1.2}Te_{2} (K_{5}Fe_{4}Ag_{6}Te_{10}, KFAT) is a local-moment magnet consisting of well-separated 2×2 Fe clusters, and in its ground state the clusters order magnetically, breaking both spin-rotational and time-reversal symmetries. Using uniform magnetic susceptibility and neutron scattering measurements, we find a small strain induces sizable spin anisotropy in the paramagnetic state of KFAT, manifestly breaking spin-rotational symmetry while retaining time-reversal symmetry, resulting in a strain-induced spin-nematic state in which the 2×2 clusters act as the spin analog of molecules in a liquid crystal nematic. The strain-induced spin anisotropy in KFAT allows us to probe its nematic susceptibility, revealing a divergentlike increase upon cooling, indicating the ordered ground state is driven by a spin-orbital entangled nematic order parameter

Atomic layer deposition process modeling and experimental investigation for sustainable manufacturing of nano thin films

Abstract: This paper studies the adverse environmental impacts of atomic layer deposition (ALD) nano-manufacturing technology on ALD of Al2O3 nano-scale thin films. Numerical simulations with detailed ALD surface reaction mechanism developed based on Density Functional Theory (DFT), and atomic-level calculations are performed to investigate the effects of four process parameters including process temperature, pulse time, purge time, and carrier gas flow rate on ALD film deposition rate, process emissions and wastes. Full-cycle ALD simulations reveal that the depositions of nano-thin-films in ALD are in essence the chemisorption of the gaseous species and the conversion of surface species. Methane emissions are positively proportional to the film deposition process. The studies show that process temperature fundamentally affects the ALD chemical process by changing the energy states of the surface species. Pulse time is directly related to the precursor dosage. Purge time influences the ALD process by changing the gas-surface interaction time, and higher carrier gas flow rate alters the ALD flow field by accelerating the convective heat and mass transfer in ALD process

Determination of Time of Oil Cracking into Gas in Weiyuan Paleo-Oil Pool in Sichuan Basin, South China

Weiyuan gas field, located in the Sichuan basin of south China, is a large marine gas field with the oldest reservoir (the Sinian sequences) in south China. The hydrocarbon origin of the gas field has long been debated by petroleum geologists. Recently, it was recognized that a paleo-oil pool maybe the significant contributor to the gas field. Consequently, when the paleo-oil pool had been cracked into gas has become an interesting topic. Actually, the time determination of oil cracking into gas is of significance to marine gas reservoir exploration in south China, because it is a pervasive hydrocarbon resource of marine gas reservoirs in south China. Characteristics of the gas composition, fluid inclusion, and bitumen in Sinian reservoir show that the present-day Weiyuan gas field originates from a paleo-oil pool cracked at high temperature. Data collected from the previous documents show that the temperature window of oil cracking into gas is around 160 to 210 °C on a geological time scale. On the basis of vitrinite reflectance, the heat flow history and erosion thickness in Weiyuan area were reconstructed. With the combination of heat flow history and burial history, the temperature history the paleo-oil pool experienced was reconstructed. The time of the paleo-oil cracking into gas is determined according to the oil cracking temperature window. The results show that the oil in the Weiyuan Sinian paleo-oil pool cracked into gas during the late Triassic to Eocene age.</span

Progress on the Preparation of Nano-hydroxyapatite and its Application in Water Treatment

This is an article in the field of ceramics and composites. Hydroxyapatite (HAP) has excellent ion exchange performance, shows good adsorption capacity for heavy metal ions, harmful anions, and organics in wastewater, and will not cause secondary pollution in the process of wastewater treatment. Thus, it is a promising green adsorbent. Due to its small size and large specific surface area, nano-hydroxyapatite (nHAP) exposes more adsorption sites, showing supreme adsorption capacity. It is a tendency to produce nHAP composites of strong adsorption capacity, easy for solid-liquid separation and regeneration, and low-cost. This article reviews the recent research progress of nano-HAP and its composites as adsorbents for wastewater treatment, and prospects the application of them as adsorbents