Principled analytic classifier for positive-unlabeled learning via weighted integral probability metric

Machine Learning - We consider the problem of learning a binary classifier from only positive and unlabeled observations (called PU learning). Recent studies in PU learning have shown superior...     

A time-varying lot sizes approach for the economic lot scheduling problem with returns

We consider the economic lot scheduling problem with returns by assuming that each item is returned by a constant rate of demand. The goal is to find production frequencies, production sequences, production times, as well as idle times for several items subject to returns at a single facility. We propose a heu ristic algorithm based on a time-varying (TV) lot sizes approach. The problem is decomposed into two distinct portions: in the first, we find a combinatorial part (production frequencies and sequences) and in the second, we determine a continuous part (production and idle times) in a specific production sequence. We report computational results that show that, in many cases, the proposed TV lot sizes approach with consideration of returns yields a relatively minor error.     

Electrochemical characteristics of semi conductive silicon anode for lithium polymer batteries

In this paper, the electrochemical characteristics of semi conductive silicon thin films (n-type and p-type silicon) anodes integrated with the solid polymer electrolyte for lithium polymer batteries were investigated. The charge/discharge cycling tests revealed that the phosphorus-doped n-type silicon electrode shows the most stable cyclic performance after the 40^th cycle and still maintains a reversible specific capacity of about 2,500 mAh/g. The enhanced electrochemical performance of the doped silicon anode was attributed to the enhancement of its electrical conductivity, which was further confirmed by impedance spectroscopy and surface analysis by XPS.     

Effects of ZnO coating on electrochemical performance and thermal stability of LiCoO2 as cathode material for lithium-ion batteries

ZnO-coated LiCoO₂ particles are prepared by plasma-enhanced chemical vapour deposition (PE-CVD) in a coating range from 0.08 to 0.49 wt.%, and examined using field emission-scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and atomic absorption spectroscopy (AAS), with particular focus on surface characteristics. From charge-discharge cycling tests in the range of 3.0–4.5 V, the ZnO coating has little effect on the discharge capacity in the first few cycles, but the coating effectively improves the capacity retention after prolonged cycling. In the experimental range studied, the optimum amount of ZnO coating which maximizes the capacity retention is found to be 0.21 wt.%. An excessive amount of ZnO coating causes a decrease in both cyclic performance and thermal stability. The possible reasons for enhanced cycleability and thermal stability afforded by the ZnO coating are discussed from the viewpoint of the surface morphology of the bare and coated LiCoO₂ particles and their impedance spectra.     

Oxygen Surface Exchange at Grain Boundaries of Oxide Ion Conductors

The role of grain boundaries on oxygen surface exchange in an oxide ion conductor is reported. Atomic‐scale characterization of the microstructure and chemical composition near the grain boundaries of gadolinia‐doped ceria (GDC) thin films show the segregation of dopants and oxygen vacancies along the grain boundaries using the energy dispersive spectroscopy in scanning transmission electron microscopy (STEM‐EDS). Kelvin probe microscopy is employed to verify the charge distribution near grain boundaries and shows that the grain boundary is positively charged, indicating a high concentration of oxygen vacancies. AC impedance spectroscopy on polycrystalline GDC membranes with thin interfacial layers with different grain boundary densities at the cathodes demonstrated that the cells with higher grain boundary density result in lower electrode impedance and higher exchange current density. These experimental evidences clearly show that grain boundaries on the surface provide preferential reaction sites for facilitated oxygen incorporation into the GDC electrolyte.     

Discovery of Zr-based metal-organic polygon:Unveiling new design opportunities in reticular chemistry

Metal-based secondary building unit and the shape of organic ligands are the two crucial factors for determining the final topology of metal-organic materials.A careful choice of organic and inorganic structural building units occasionally produces unexpected structures,facilitating deeper fundamental understanding of coordination-driven self-assembly behind metal-organic materials.Here,we have synthesized a triangular metal-organic polygon(MOT-1),assembled from bulky tetramethyl terephthalate and Zr-based secondary building unit.Surprisingly,the Zr-based secondary building unit serves as an unusual ditopic Zr-connector,toform metal-organic polygon MOT-1,proven to be a good candidate for water adsorption with recyclability.This study highlights the interplay of the geometrically frustrated ligand and secondary building unit in controlling the connectivity of metal-organic polygon.Such a strategy can be further used to unveil a new class of metal-organic materials.     

Synthesis of nanostructured Li2MnSiO4/C using a microwave assisted sol–gel process with water as a base solvent

Microwave assisted sol–gel method is used to fabricate nanostructured Li₂MnSiO₄/C composites. Our process has the advantages in homogenous heating and reduced reaction time. In addition, the water is used as a base solvent while the conventional microwave-solvothermal method use the organic solvent as the base solvent, which makes our process much more safe and economical. Here, our prepared Li₂MnSiO₄/C composite exhibits an enhanced discharge capacity of 173.1 mAh g^?1, compared to the conventional processes.     

Protein-Precoated Surface of Metal-Organic Framework Nanoparticles for Targeted Delivery

Metal-organic framework (MOF) nanoparticles have recently emerged as a promising vehicle for drug delivery with high porosity and feasibility. However, employing a MOF-based drug delivery system remains a challenge due to the difficulty in controlling interfaces of particles in a biological environment. In this paper, protein corona-blocked Zr₆-based MOF (PCN-224) nanoparticles are presented for targeted cancer therapy with high efficiency. The unmodified PCN-224 surface is precoated with glutathione transferase (GST)-fused targetable affibody (GST-Afb) proteins via simple mixing conjugations instead of chemical modifications that can induce the impairment of proteins. GST-Afb proteins are shown to stably protect the surface of PCN-224 particles in a specific orientation with GST adsorbed onto the porous surface and the GST-linked Afb posed outward, minimizing the unwanted interfacial interactions of particles with external biological proteins. The Afb-directed cell-specific targeting ability of particles and consequent induction of cell death is demonstrated both in vitro and in vivo by using two kinds of Afb, which targets the surface membrane receptor, human epidermal growth factor receptor 2 (HER2) or epidermal growth factor receptor (EGFR). This study provides insight into the way of regulating the protein-adhesive surface of MOF nanoparticles and designing a more effective MOF-hosted targeted delivery system.     

Effects of transition metal doping and surface treatment to improve the electrochemical performance of Li2MnO3

A novel strategy to improve the electrochemical performance of Li₂MnO₃ using transition metal doping by the mechanochemical process is proposed. Li₂MnO₃ precursors are treated with transition metal containing chemicals in the mechanochemical process, followed by heat treatment. Cr containing Li₂MnO₃, with only 1 mol% Cr doping, exhibits unique electrochemical properties with a large initial discharge capacity of 234.9 mAh?g^?1, which is superior to the 205.0 mAh?g^?1 of pristine Li₂MnO₃, and all other transition-metal containing oxides. The structures of Li₂MnO₃ and Li₂MnO₃ with the transition metal element doping (TM-Li₂MnO₃) are studied by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), and the electrochemical characteristics are further investigated using electrochemical impedance spectroscopy (EIS) measurements.