HGR-Net: Hierarchical Graph Reasoning Network for Arbitrary Shape Scene Text Detection.

As a prerequisite step of scene text reading, scene text detection is known as a challenging task due to natural scene text diversity and variability. Most existing methods either adopt bottom-up sub-text component extraction or focus on top-down text contour regression. From a hybrid perspective, we explore hierarchical text instance-level and component-level representation for arbitrarily-shaped scene text detection. In this work, we propose a novel Hierarchical Graph Reasoning Network (HGR-Net), which consists of a Text Feature Extraction Network (TFEN) and a Text Relation Learner Network (TRLN). TFEN adaptively learns multi-grained text candidates based on shared convolutional feature maps, including instance-level text contours and component-level quadrangles. In TRLN, an inter-text graph is constructed to explore global contextual information with position-awareness between text instances, and an intra-text graph is designed to estimate geometric attributes for establishing component-level linkages. Next, we bridge the cross-feed interaction between instance-level and component-level, and it further achieves hierarchical relational reasoning by learning complementary graph embeddings across levels. Experiments conducted on three publicly available benchmarks SCUT-CTW1500, Total-Text, and ICDAR15 have demonstrated that HGR-Net achieves state-of-the-art performance on arbitrary orientation and arbitrary shape scene text detection.

Effect of Copper Doping on Electronic Structure and Optical Absorption of Cd33Se33 Quantum Dots.

The photophysical properties of Cu-doped CdSe quantum dots (QDs) can be affected by the oxidation state of Cu impurity, but disagreement still exists on the Cu oxidation state (+1 or +2) in these QDs, which is debated and poorly understood for many years. In this work, by using density functional theory (DFT)-based calculations with the Heyd-Scuseria-Ernzerhof (HSE) screened hybrid functional, we clearly demonstrate that the incorporation of Cu dopants into the surface of the magic sized Cd33Se33 QD leads to non-magnetic Cu 3d orbitals distribution and Cu+1 oxidation state, while doping Cu atoms in the core region of QDs can lead to both Cu+1 and Cu+2 oxidation states, depending on the local environment of Cu atoms in the QDs. In addition, it is found that the optical absorption of the Cu-doped Cd33Se33 QD in the visible region is mainly affected by Cu concentration, while the absorption in the infrared regime is closely related to the oxidation state of Cu. The present results enable us to use the doping of Cu impurity in CdSe QDs to achieve special photophysical properties for their applications in high-efficiency photovoltaic devices. The methods used here to resolve the electronic and optical properties of Cu-doped CdSe QDs can be extended to other II-VI semiconductor QDs incorporating transition-metal ions with variable valence.

The thermodynamic stability and mechanical properties of TiCxN1-x(0⩽x⩽ 1) compounds by cluster expansion method and first-principles calculations.

The thermodynamic stability and mechanical properties of titanium carbonitrides TiCxN1-x(0 ⩽x⩽ 1) are investigated by a combination of the universal cluster expansion method and the first-principles calculations. By considering the ordering of the N/C distributions on the anion sublattice sites of TiCxN1-x, a binary diagram of the heat of formation is constructed, and seven kinds of ground-state structures are predicted in the whole range of 0 ⩽x⩽ 1. These predicted ground-state TiCxN1-xstructures are further proved to be dynamically and mechanically stable by examining their phonon dispersion spectra and elastic constants. Further studies indicate that the mechanical and thermodynamic properties of the ternary TiCxN1-xstructures are generally better than those of the binary TiC or TiN, while the differences within the ternary systems are insignificant. The possible origin of the enhancement of the mechanical and thermodynamic properties of the predicted ground-state TiCxN1-xare discussed together with the electronic structures.

Corrosion kinetics and mechanisms of ZrC1-x ceramics in high temperature water vapor.

The corrosion kinetics and mechanisms of ZrC1-x ceramics in water vapor between 800 and 1200 °C were investigated. The results showed that there was only cubic ZrO2 phase in the corrosion layer when corroded at 800 °C, while a scale layer consisted of a mixture of cubic and monoclinic ZrO2 phases when corroded at 1000 °C and 1200 °C. A series of crystallographic relationships at the ZrC/c-ZrO2 interface were detected. The c-ZrO2 formed near the interface retained some crystallographic orientations of the initial ZrC before corrosion, presenting an "inheritance in microstructure" between c-ZrO2 and ZrC. The corrosion behavior mainly followed a parabolic relationship. The incremental rate of weight gain increased with increased corrosion temperature and decreased C/Zr ratio and the carbon vacancy was passive to the decrease of corrosion rate. The main corrosion controlling mechanism changed from phase boundary reactions to surface diffusion and then to grain boundary diffusion with increased temperature.

Determination of copper (II) in foodstuffs based on its quenching effect on the fluorescence of N,N'-bis(pyridoxal phosphate)-o-phenylenediamine.

A Schiff base-type fluorescence probe was prepared for the detection of copper (II) in foodstuffs. The probe is N,N'-bis(pyridoxal phosphate)-o-phenylenediamine (BPPP). It was synthesized by utilizing the Schiff base condensation reaction of pyridoxal 5-phosphate with 1,2-phenylenediamine. BPPP has the properties of high fluorescence stability, good water solubility and low toxicity. Its maximum excitation wavelength and maximum fluorescence emission wavelength are at 389 and 448 nm, respectively. When BPPP coexists with copper (II), its fluorescence is dramatically quenched. Under a certain condition, the fluorescence intensity decreased proportionally to the concentration of copper (II) by the quenching effect. Based on this fact, we established a fluorescence quenching method for the determination of copper (II). Under optimal conditions a linear range was found to be 0.5-50 ng/mL with a detection limit of 0.2 ng/mL. The method has been applied to determine copper (II) in foodstuff samples and the analytical results show good agreement with that obtained from atomic absorption spectrometry method.

Spectroscopic study on the reactions of bis-salophen with uranyl and then with fructose 1,6-bisphosphate and the analytical application.

The chelating reaction of bis-salophen with uranyl to form binuclear complex uranyl-bis-salophen (UBS) was studied by fluorescence spectroscopy. The coordination reaction of UBS with fructose 1,6-bisphosphate (F-1,6-BP) to form supramolecular polymer was then studied by resonance light scattering (RLS) spectroscopy. The reaction of bis-salophen with uranyl results in a remarkable enhancement of fluorescence intensity. The maximum emission wavelength of the fluorescence is at 471nm. The reaction of UBS with F-1,6-BP results in a remarkable enhancement of RLS intensity. The maximum scattering wavelength of the RLS is at 460nm. The two reactions were used to establish fluorescence method for the determination of uranium (VI) and RLS method for the determination of F-1,6-BP, respectively. Under optimum conditions, the linear ranges for the detection of uranium (VI) and F-1,6-BP are 0.003-0.35nmol/mL and 0.05-5.0nmol/mL, respectively. The detection limits are 0.0017nmol/mL and 0.020nmol/mL, respectively. The proposed fluorescence method has been successfully applied for the determination of uranium (VI) in environmental water samples with the recoveries of 97.0-104.0%. The proposed RLS method has also been successfully applied for the determination of F-1,6-BP in medicine injection samples with the recoveries of 98.5-102.3%.