Efficient Method for Prediction of Metastable or Ground Multipolar Ordered States and Its Application in Monolayer α-RuX_{3} (X=Cl, I).

Exotic high-rank multipolar order parameters have been found to be unexpectedly active in more and more correlated materials in recent years. Such multipoles are usually dubbed "hidden orders" since they are insensitive to common experimental probes. Theoretically, it is also difficult to predict multipolar orders via ab initio calculations in real materials. Here, we present an efficient method to predict possible multipoles in materials based on linear response theory under random phase approximation. Using this method, we successfully predict two pure metastable magnetic octupolar states in monolayer α-RuCl_{3}, which is confirmed by self-consistent unrestricted Hartree-Fock calculations. We then demonstrate that these octupolar states can be stabilized in monolayer α-RuI_{3}, one of which becomes the octupolar ground state. Furthermore, we also predict a fingerprint of an orthogonal magnetization pattern produced by the octupole moment that can be easily detected by experiment. The method and the example presented in this Letter serve as a guide for searching multipolar order parameters in other correlated materials.

Ancestral sequence reconstruction of the prokaryotic three-domain laccases for efficiently degrading polyethylene.

Biodegradation of polyethylene (PE) plastics is environmentally friendly. To obtain the laccases that can efficiently degrade PE plastics, we generated 9 ancestral laccases from 23 bacterial three-domain laccases through ancestral sequence reconstruction. The optimal temperatures of the ancestral laccases were between 60 °C-80 °C, while their optimal pHs were at 3.0 or 4.0. Without substrate pretreatment and mediator addition, all the ancestral laccases can degrade low-density polyethylene (LDPE) films at pH 7.0 and 60 °C. Among them, Anc52, which shared low sequence identity (18 %-41.7 %) with the reported PE-degrading laccases, was the most effective for LDPE degradation. After the catalytic reactions at 90 °C for 14 h, Anc52 (0.2 mg/mL) induced clear wrinkles and deep pits on the PE film surface detected by scanning electron microscope, and its carbonyl and hydroxyl indices reached 2.08 and 2.42, respectively. Then, we identified the residues 203 and 288 critical for PE degradation through site-directed mutation on Anc52. Moreover, Anc52 be activated by heat treatment (60 °C and 90 °C) at pH 7.0, which gave it a high catalytic efficiency (kcat/Km= 191.73 mM-1·s-1) and thermal stability (half-life at 70 °C = 13.70 h). The ancestral laccases obtained here could be good candidates for PE biodegradation.

Optimization and evaluation of resveratrol amorphous solid dispersions with a novel polymeric system.

The preparation of amorphous solid dispersions using polymers is a commonly used formulation strategy for enhancing the solubility of poorly water-soluble drugs. However, a single polymer often does not bring significantly enhance the solubility or amorphous stability of a poorly water-soluble drug. We found an application of a unique and novel binary polymeric blend in the preparation of solid dispersions. The main purpose of this study is to optimize and evaluate resveratrol (Res) amorphous solid dispersions with a novel polymeric system of poly (vinyl pyrrolidone) (PVP) and carboxymethyl chitosan (CMCS). The influence of three different release factors, the ratio of CMCS to the polymer mixture (CMCS% = X1), the ratio of Res to the polymer mixture (Res% = X2) and the surfactant (Tween 80 = X3), on the characteristics of released Res at various times (Q5 and Q30) was investigated. The computer optimization and contour plots were used to predict the levels of the independent variables as X1 = 0.17, X2 = 0.10 and X3 = 2.94 for maximized responses of Q5 and Q30. Fourier transform infrared spectroscopy (FTIR) results revealed that each polymer formed hydrogen bonds with Res. The solid performance and physical stability of the optimized ternary dispersions were studied with scanning electron microscopy (SEM), powder X-ray diffraction (XRD), modulated differential scanning calorimetry (MDSC) and dissolution testing. SEM, XRD and MDSC analysis demonstrated that the Res was amorphous, and MDSC showed no evidence of phase separation during storage. Dissolution testing indicated a more than fourfold increase in the apparent solubility of the optimized ternary dispersions, which maintained high solubility after 90 days. In our research, we used CMCS as a new carrier in combination with PVP, which not only improved the in vitro dissolution of Res but also had better stability.

Carbon dioxide bubble-propelled microengines in carbonated water and beverages.

We demonstrate a new type of gaseous fuel for rolled-up tubular Ti/Cr microengine powered by carbon dioxide microbubbles in carbonated water and brewed beverages. Existence of microbubble pockets is revealed using on-chip integrated transparent microtubes. Vertical position, angle of rotation and buoyancy of ferromagnetic Ti/Fe/Cr microengines are controlled using an external magnetic field.

Designing artificial two dimensional electron lattice on metal surface: a Kagome-like lattice as an example.

Recently, a new kind of artificial two dimensional (2D) electron lattice on the nanoscale, i.e. molecular graphene, has drawn a lot of interest, where the metal surface electrons are transformed into a honeycomb lattice via absorbing a molecular lattice on the metal surface [Gomes et al., Nature, 2012, 438, 306; Wang et al., Phys. Rev. Lett., 2014, 113, 196803]. In this work, we theoretically demonstrate that this technique can be readily used to build other complex 2D electron lattices on a metal surface, which are of high interest in the field of condensed matter physics. The main challenge to build a complex 2D electron lattice is that this is a quantum antidot system, where the absorbed molecule normally exerts a repulsive potential on the surface electrons. Thus, there is no straightforward corresponding relation between the molecular lattice pattern and the desired 2D lattice of surface electrons. Here, we give an interesting example about the Kagome lattice, which has exotic correlated electronic states. We design a special molecular pattern and show that this molecular lattice can transform the surface electrons into a Kagome-like lattice. The numerical simulation is conducted using a Cu(111) surface and CO molecules. We first estimate the effective parameters of the Cu/CO system by fitting experimental data of the molecular graphene. Then, we calculate the corresponding energy bands and LDOS of the surface electrons in the presence of the proposed molecular lattice. Finally, we interpret the numerical results by the tight binding model of the Kagome lattice. We hope that our work can stimulate further theoretical and experimental interest in this novel artificial 2D electron lattice system.