Search

Whilst metal borates are well known as optical materials, their potential in solid catalysis has been less investigated. The calcite structured InBO3 was selected as the target borate and was prepared using a solvothermal method. High-resolution transmission electron microscopy and powder X-ray diffraction prove that the material has a nanoparticle morphology with an average size ∼50 nm and high crystallinity. Intrinsic surface oxygen vacancies, which are beneficial to catalysis, were detected using X-ray photoelectron spectroscopy. Lewis acidity and basicity were both observed using NH3-/CO2-temperature-programmed desorption experiments, and the total acid and base amounts were found to be 46.6 and 123.8 μmol g−1, respectively. Catalytic dehydration and dehydrogenation reactions for isopropanol at elevated temperatures were conducted in a fixed bed reactor to evaluate the catalytic performance of InBO3. InBO3 exhibits a high conversion rate (>90.5%) and, most importantly, a high dehydrogenation selectivity (acetone selectivity >92.5%), whilst the optimal acetone yield achieved was 121.3 mmol h−1 g−1cat at 350 °C. This study on InBO3 strongly suggests that metal borates have promising applications in heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

Microglia, the major immune cells in the brain, mediate neuroinflammation, increased oxidative stress, and impaired neurotransmission in Alzheimer's disease (AD), in which most AD risk genes are highly expressed. In microglia, due to the limitations of current single-omics data analysis, risk genes, the regulatory mechanisms, the mechanisms of action of immune responses and the exploration of drug targets for AD immunotherapy are still unclear. Therefore, we proposed a method to integrate multi-omics data based on the construction of gene regulatory networks (GRN), by combining weighted gene co-expression network analysis (WGCNA) with single-cell regulatory network inference and clustering (SCENIC). This enables snRNA-seq data and bulkRNA-seq data to obtain data on the deeper intermolecular regulatory relationships, related genes, and the molecular mechanisms of immune-cell action. In our approach, not only were central transcription factors (TF) STAT3, CEBPB, SPI1, and regulatory mechanisms identified more accurately than with single-omics but also immunotherapy targeting central TFs to drugs was found to be significantly different between patients. Thus, in addition to providing new insights into the potential regulatory mechanisms and pathogenic genes of AD microglia, this approach can assist clinicians in making the most rational treatment plans for patients with different risks; it also has significant implications for identifying AD immunotherapy targets and targeting microglia-associated immune drugs. [ABSTRACT FROM AUTHOR]

Clustering analysis is one of the most important technologies for single-cell data mining. It is widely used in the division of different gene sequences, the identification of functional genes, and the detection of new cell types. Although the traditional unsupervised clustering method does not require label data, the distribution of the original data, the setting of hyperparameters, and other factors all affect the effectiveness of the clustering algorithm. While in some cases the type of some cells is known, it is hoped to achieve high accuracy if the prior information about those cells is utilized sufficiently. In this study, we propose SCMAG (a semisupervised single-cell clustering method based on a matrix aggregation graph convolutional neural network) that takes into full consideration the prior information for single-cell data. To evaluate the performance of the proposed semisupervised clustering method, we test on different single-cell datasets and compare with the current semisupervised clustering algorithm in recognizing cell types on various real scRNA-seq data; the results show that it is a more accurate and significant model. [ABSTRACT FROM AUTHOR]

Introduction: Acute lymphocytic leukemia (ALL) is a hematologic malignancy caused by the clonal proliferation of immature lymphocytes. Long noncoding RNAs (lncRNAs) have been reported as critical regulators in several cancers, including ALL. LncRNA SLCO4A1 antisense RNA 1 (SLCO4A1‐AS1) has been revealed to be implicated in tumorigenesis of several cancers. Our study focused on the role of SLCO4A1‐AS1 in ALL. Methods: RT‐qPCR, Western blot analysis, CCK‐8, EdU, and Flow cytometry analysis were used to explore the biological function of SLCO4A1‐AS1 in ALL cellular processes. Luciferase reporter and RNA pull‐down assays were applied to explore the mechanism of SLCO4A1‐AS1 in ALL cells. Results: SLCO4A1‐AS1 was upregulated in ALL tissues and cell lines. We found that suppression of SLCO4A1‐AS1 suppressed ALL cell proliferation and facilitated cell apoptosis. Our result confirmed that SLCO4A1‐AS1 acted as a ceRNA by sponging microRNA 876‐3p (miR‐876‐3p) to upregulate retinoblastoma binding protein 6 (RBBP6) expression in ALL cells. Moreover, SLCO4A1‐AS1 activated the JNK signaling pathway by upregulating RBBP6. Rescue assays revealed that the activation of the JNK signaling or overexpression of RBBP6 revered the suppressive effect of SLCO4A1‐AS1 knockdown on growth of ALL cells. Conclusion: SLCO4A1‐AS1 promoted cell growth of ALL by the miR‐876‐3p/RBBP6 axis to activate the JNK signaling pathway. [ABSTRACT FROM AUTHOR]

Trajectory replanning for quadrotors is essential to enable fully autonomous flight in unknown environments. Hierarchical motion planning frameworks, which combine path planning with path parameterization, are popular due to their time efficiency. However, the path planning cannot properly deal with nonstatic initial states of the quadrotor, which may result in nonsmooth or even dynamically infeasible trajectories. In this article, we present an efficient kinodynamic replanning framework by exploiting the advantageous properties of the B-spline, which facilitates dealing with the nonstatic state and guarantees safety and dynamical feasibility. Our framework starts with an efficient B-spline-based kinodynamic (EBK) search algorithm, which finds a feasible trajectory with minimum control effort and time. To compensate for the discretization induced by the EBK search, an elastic optimization approach is proposed to refine the control point placement to the optimal location. Systematic comparisons against the state-of-the-art are conducted to validate the performance. Comprehensive onboard experiments using two different vision-based quadrotors are carried out showing the general applicability of the framework. [ABSTRACT FROM AUTHOR]

• A Perforated metamaterial plate with ABHs bonded by a piezoelectric stud is proposed. • Broad bandgaps and strong collimation can be achieved for the metamaterial plate. • The DQEM is proposed to obtain wave characteristics of the metamaterial plate. • Parameter study is conducted in terms of the bandgaps, EFCs and group velocities. • Directional wave manipulation is achieved by utilizing the bandgaps and collimation. Aiming at achieving lower and broader bandgaps (BGs) and stronger collimation effect, this research proposes a novel perforated metamaterial plate with acoustic black holes (ABHs) interconnected by piezoelectric studs for flexural wave manipulation. Based on the differential quadrature element method together with the first-order shear deformation plate theory, the governing equations of the metamaterial plate are derived. The proposed model is validated by comparing with finite element simulation results. Finally, the wave propagation characteristics including the BGs, equi-frequency contours (EFCs), and group velocities are obtained. The results reveal that the introduction of the stud embedded with piezoelectric patches brings wider complete BGs and stronger collimation effect at lower frequencies. The boundary frequencies and bandwidth of BGs and the preferential direction of wave energy flow are tunable by adjusting geometry parameters of the unit cell. The balance between ABH and piezoelectric effects should be kept to enhance the collimation by generating the caustic lobes. Utilizing the BG and self-collimation mechanism, flexural wave propagation can be manipulated by creating point or line defects in the metamaterial plates. This research provides guidance on the design of metamaterial structure with ABHs and piezoelectric material to achieve broadband vibration absorption and directional wave propagation. [ABSTRACT FROM AUTHOR]

Nanosized hybrid cathode materials, LiMnFePO with olivine structure anchoring on the graphene matrices, were facilely prepared by employing a modified microwave-assisted solvothermal method. Many measurements such as XRD, SEM, TEM, EDS, Raman spectra and XPS have been utilized to identify their physicochemical properties. Electron microscopy analyses revealed that the widely distributed LiMnFePO nanorods were selectively and homogeneously grown on graphene sheets with rod length of 100-200 nm and diameter of 30-50 nm. In particular, it was fully improved that the deliberate additions of conductive matrix, graphene oxide, have facilitated the specific growth of LiMnFePO and therefore improved their homogeneity and morphology to form a huge electric network. Electrochemical assessments indicated that the as-synthesized materials delivered an initial discharge capacity of 159.8 mAh g at 0.1 C and even 81.6 mAh g at 20 C, meanwhile maintained their excellent rate capability and cycling ability, about 91.7% capacity retention after 80 cycles at 1 C. Theoretically speaking, the excellent electrochemical performance maybe makes these nanosized LiMnFePO cathode materials a potential candidate for the practical implications in high-power devices and energy storage systems. [ABSTRACT FROM AUTHOR]

• A metamaterial beam with graded ABHs is proposed for broadband vibration reduction. • The DQM is utilized to model the rainbow metamaterial beam efficiently. • Rainbow metamaterial beams exhibit broader bandgaps and better attenuation effect. • Increasing graded spacing or changing graded direction leads to better attenuation. • Disordered geometry parameters lead to further improvement of attenuation strength. Acoustic black hole (ABH) structures have been widely utilized for vibration suppression owing to its tailored indentations according to a power-law profile. Compared with single ABH element, multiple ABHs embedded in periodic lattice configurations exhibit more remarkable attenuation effect within the so-called bandgaps at relatively low frequencies. However, most research is devoted to the analysis of uniform metamaterial embedded with periodic arrangement of ABHs, resulting in the attenuation bandgaps limited to a narrow frequency range. In this research, a rainbow metamaterial beam embedded with graded arrangement of ABHs is proposed to achieve broadband vibration attenuation. Two arrangement types of ABHs in metamaterial beams including linear and sinusoidal profiles are taken into account. The differential quadrature method is used to establish governing equations of infinite beams with periodic ABHs and finite rainbow metamaterials with graded ABHs, respectively. Using the validated mathematical model and genetic algorithm, wave propagation behaviors in infinite metamaterial beams, transmittance characteristics and optimization of finite rainbow metamaterial beams are investigated quantitatively. The results reveal that the generation of broad bandgaps can be explained by the combination of local resonance and Bragg scattering effects for proposed metamaterial beams with periodic asymmetrical ABHs. The corresponding bandgaps are tunable by changing the geometry parameters of ABHs. Moreover, the rainbow metamaterial beams with linear and sinusoidal ABHs own a broader attenuation band and better attenuation effect compared to the periodic ones. Compared with regular graded distributions, disordered arrangement of geometry parameters of neighboring cells leads to further improvement of attenuation strength. This work provides novel perspectives on achieving broadband vibration attenuation by rainbow metamaterial beams with ABHs, and the results could be applied to guide the design of rainbow metamaterial with graded geometry parameters. [Display omitted] [ABSTRACT FROM AUTHOR]

Using atmospheric observational data from 1998 to 2013, station rainfall data, TRMM (Tropical Rainfall Measuring Mission) data, as well as annual statistics for the plateau vortex and shear line, the joint activity features of sustained departure plateau vortexes (SDPVs) and southwest vortexes (SWVs) are analyzed. Some new and useful observational facts and understanding are obtained about the joint activities of the two types of vortex. The results show that: (1) The joint active period of the two vortexes is from May to August, and mostly in June and July. (2) The SDPVs of the partnership mainly originate near Zaduo, while the SWVs come from Jiulong. (3) Most of the two vortexes move in almost the same direction, moving eastward together with the low trough. The SDPVs mainly act in the area to the north of the Yangtze River, while the SWVs are situated across the Yangtze River valley. (4) The joint activity of the two vortexes often produces sustained regional heavy rainfall to the south of the Yellow River, influencing wide areas of China, and even as far as the Korean Peninsula, Japan and Vietnam. (5) Most of the two vortexes are baroclinic or cold vortexes, and they both become strengthened in terms of their joint activity. (6) When the two vortexes move over the sea, their central pressure descends and their rainfall increases, especially for SWVs. (7) The two vortexes might spin over the same area simultaneously when there are tropical cyclones in the eastern and southern seas of China, or move southward together if a tropical cyclone appears near Hainan Island. [ABSTRACT FROM AUTHOR]

Luminescence studies on rare earth borates have been active for a long time. Here we performed a careful synthesis to prepare pure samples of La1−xEux[B8O11(OH)5] (0 ≤x≤ 0.135) using the boric acid flux method, and after evaluating its thermal behavior by thermogravimetric analysis and powder X-ray diffraction, an appropriate thermal treatment was applied to prepare anhydrous β-La1−xEuxB5O9 (810 °C, 10 h), thus allowing for the study of their Eu3+-luminescence in a relatively wide range of Eu3+-concentrations. The comparatively strong f–f transition of La1−xEux[B8O11(OH)5] in the excitation spectra suggests its potential as a red-emitting phosphor for white-light emitting diodes, which can be efficiently excited by ultraviolet-light emitting diode chips and show the strongest red emission at 622 nm. In contrast, β-La1−xEuxB5O9 shows a very intense O2−→ Eu3+ CT absorption, and give strong red emissions with red/orange ratios ∼2.4. Both La1−xEux[B8O11(OH)5] and β-La1−xEuxB5O9 show no concentration quenching up to the maximal x = 0.135, which is as-expected due to their large spatial distances between rare earth cations. It is the first time to study the luminescent performance when La[B8O11(OH)5] and β-LaB5O9 were used as hosts. In addition, La0.93Eu0.07[B8O11(OH)5] was selected as a representative to study the luminescence evolution during thermal treatments. [ABSTRACT FROM AUTHOR]

The dual‐site synergistic effect in heterogeneous catalysis is quite interesting, and also complex because at least two substrate molecules are adsorbed or activated on the catalyst surface, which apparently needs two spatially separated and functionally independent active sites. It would become more difficult when the substrate molecules are large ones. The replacement of Al3+ in Al4B6O15 lattice with Co2+ leads to the formation of unsaturated Co2+ (4‐fold coordination) along with oxygen vacancies (Ov). The former one behaves as a medium‐strength Lewis acid site, and can adsorb and activate molecules with a nitro group (e. g., β‐nitrostyrene). The latter one can adsorb and activate oxygen species, which further activates the indole derivatives. Next, the spatially separated dual sites on the catalyst surface can synergistically and efficiently catalyze their Friedel‐Crafts alkylation reactions under mild conditions. The high durability can be proved by the as‐maintained high yields, that is, 98, 93, 96, 92 and 90 % for 5 runs, respectively. The reaction kinetics obey the second‐order characteristic. Annealing under hydrogen condition can further generate more surficial Ov, leading to an improvement to the catalytic activity. A simple and probably routine aliovalent doping endows such a complex synergistic catalysis involving two large substrate molecules, providing an inspired perspective of developing dual‐site catalysts. [ABSTRACT FROM AUTHOR]

Rietveld refinements were performed on CaBaZn2Ga2−xAlxO7 (x = 0, 1, 2) to investigate the site preference of cations in tetrahedral cavities. Tri-valent Ga3+/Al3+ preferred the tetrahedral sites (T1-sites) within the triangular layers. Moreover, a layered type cationic ordering was observed in CaBaZn2Al2O7, where all the T1-sites were occupied by Al3+. This represents the first example of a cationic ordering in “114” compounds. By substituting Al3+ into CaBaZn2Ga2O7, the major change in the structure was the shrinkage of the T1O4 tetrahedrons, especially the shortening of the T1–O2 bond distance along the c-axis, which led to an anisotropic shrinkage of the unit cell. In the literature, such an anisotropic change of unit cell would induce a structure distortion, as well as a decrease in the symmetry from P63mc to Pbn21. All the title compounds crystallized in P63mc, which is unexpected. A comparison with the selected “114” magnetic oxides help us to confirm that the strong antiferromagnetic interactions of magnetic lattices would also be beneficial for symmetry lowering. Overall, the factors affecting cationic ordering on T1-sites and symmetry lowering are discussed for the title compounds, which may also be applicable to other “114” oxides. [ABSTRACT FROM AUTHOR]

Scheelite compounds with Eu3+ substitution are well-known red-phosphors. We prepared and performed a detailed structural characterization of A1–1.5xEux□0.5xWO4 and A0.64–0.5yEu0.24Liy□0.12–0.5yWO4 (A = Ca, Sr; □ = vacancy) to confirm the A-site vacancy mechanism for charge balance when bivalent A cations were substituted by Eu3+. All compounds crystallize in I41/a with a disordered arrangement of A2+, Eu3+, □ at the A-site. The title compounds are all good red phosphors with a high R/O ratio (∼10), indicating that Eu3+ is located at a significantly distorted cavity. A1–1.5xEux□0.5xWO4 shows a saturation phenomenon at a high doping level, x = 0.20. With the incorporation of Li+, the emission intensity was generally enhanced compared to the Li+-free samples, moreover, an increase of the Li+ content reduces the content of vacancies, resulting in further increase of the luminescence intensity. [ABSTRACT FROM AUTHOR]

Sol–gel method was applied to prepare homogenous and highly crystalline phosphors with the formulas α-GdB5O9:xTb3+ (0 ≤x≤ 1), α-Gd1−xCexB5O9 (0 ≤x≤ 0.40), α-GdB5O9:xCe3+, 0.30Tb3+ (0 ≤x≤ 0.15) and α-GdB5O9:0.20Ce3+, xTb3+ (0 ≤x≤ 0.10). The success of the syntheses was proved by the linear shrinkage or expansion of the cell volumes against the substitution contents. In α-GdB5O9:xTb3+, an efficient energy transfer from Gd3+ to Tb3+ was observed and there was no luminescence quenching. The exceptionally high efficiency of the f–f excitations of Tb3+ implies that these phosphors may be good green-emitting UV-LED phosphors. For α-Gd1−xCexB5O9, Ce3+ absorbs the majority of the energy and transfers it to Gd3+. Therefore, the co-doping of Ce3+ and Tb3+ leads to a significant enhancement in the green emission of Tb3+. Our current results together with the study on α-GdB5O9:xEu3+ in the literature indicate that α-GdB5O9 is a good phosphor host with advantages including controllable preparation, diverse cationic doping, the absence of concentration quenching, and effective energy transfer. [ABSTRACT FROM AUTHOR]

In the meteorology of Global Navigation Satellite System, the weighted mean temperature (Tm) is a key parameter in the process of converting the zenith wetness delay into precipitable water vapor, and it plays an important role in water vapor monitoring. In this research, two deep learning algorithms, namely, recurrent neural network (RNN) and long short-term memory neural network (LSTM), were used to build a high-precision weighted mean temperature model for China using their excellent time series memory capability. The model needs site location information and measured surface temperature to predict the weighted mean temperature. We used data from 118 stations in and around China provided by the Integrated Global Radiosonde Archive from 2010 to 2015 to train the model and data from 2016 for model testing. The root mean square error (RMSE) of the RNN_Tm and LSTM_Tm models were 3.01 K and 2.89 K, respectively. Compared with the values calculated by the empirical GPT3 model, the accuracy was improved by 31.1% (RNN_Tm) and 33.9% (LSTM_Tm). In addition, we selected another 10 evenly distributed stations in China and used the constructed model to test the prediction capability of the weighted mean temperature from 2010 to 2016. The RMSE values were 2.95 K and 2.86 K, which proved that the model also exhibits high generalization in non-modeling sites in China. In general, the RNN_Tm and LSTM_Tm models have a good performance in weighted mean temperature prediction. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we study the asymptotic decay rates to the planar rarefaction waves to the Cauchy problem for a hyperbolic–elliptic coupled system called as a model system of the radiating gas in () if the initial perturbations corresponding to the planar rarefaction waves are sufficiently small in () (). The analysis is based on the -energy method and several special interpolation inequalities. [Copyright &y& Elsevier]

Abstract: In this paper, we will study the Cauchy problem for the generalized KdV–Burgers–Kuramoto equation, which represents a dissipative, stroboscopic and unstable system in physics. When the initial data is a small disturbance of a rarefaction wave of the inviscid Burgers equation, we prove the global existence of the solution to the corresponding Cauchy problem and asymptotic stability of the rarefaction wave. The analysis is based on a priori estimates and the -energy method. [Copyright &y& Elsevier]

Abstract: Let be a bounded domain in with the origin , , ; and are two smooth functions on . In this paper, we investigate the singular elliptic equation with Dirichlet boundary conditions. We study the limit behavior of the (P.S.) sequence of the corresponding energy functional and give a global compactness theorem, and then give some existence results. [Copyright &y& Elsevier]

Titania supported palladium–copper bimetallic catalysts (Pd–Cu/TiO2) are prepared by liquid-phase chemical reduction method and then applied in the catalytic reduction of nitrite ions in drinking water. The nitrite conversion and selectivity to N2 influenced by metal molar ratio (Pd:Cu), H2 flow rate, CO2 flow rate, pH value of solution and reaction temperature are also discussed in detail with physical characterizations methods such as XPS, XRD, in situ FT-IR. It is discovered that bimetallic Pd–Cu/TiO2 catalyst has higher activity than monometallic Pd/TiO2 catalyst in the catalytic reduction of nitrite ions and a mechanism is proposed to explain this promoting effect of bimetallic catalyst in this paper. [Copyright &y& Elsevier]

Photocatalytic reduction of nitrate in the presence of hole scavenger has been studied by using TiO2-supported bimetallic catalysts for the first time. Compared with monometallic catalysts, bimetallic catalysts, especially Ni–Cu/TiO2 catalyst, show more excellent photocatalytic reduction activity. Furthermore, the effects of metal weight ratio, total metal content, different hole scavengers and pH value of the solution are also investigated. It is found that pH value of reaction solution plays an important role in the photocatalytic reduction of nitrate ions. A mechanism is proposed to discuss enhancement effect of the bimetallic catalyst in photocatalytic reduction of nitrate ions in this paper. [Copyright &y& Elsevier]

Consideration is given to the FitzHugh–Nagumo equations ut=uxx-f(u)-v,vt=#x03B5;(u-γv), where f(u)=u(u-1)(u-a), 0, #x03B5;>0,γ>9/((1-2a)(2-a)). It is shown that there exist some co>0 so that the system has a heteroclinic travelling wave solution with wave speed co for any #x03B5;>0, and there exists coo∈(0,co), such that (1.2) has a homoclinic solution with wave speed coo if and only if #x03B5;γ2<1. [Copyright &y& Elsevier]

Photocatalytic reduction of nitrate ions was examined by using Cu/MgTiO3-TiO2 catalyst in the presence of sodium oxalate as hole scavenger. Many factors such as catalyst calcination temperature, Cu:Mg atom molar ratio, different hole scavengers and different concentrations of sodium oxalate were tested to search for the optimal reaction conditions. X-ray diffraction (XRD) and Transmission Electron Micrograph (TEM) were performed to characterize the composite semiconductors catalyst. Our results indicated that Cu/MgTiO3-TiO2 catalyst calcined at 873 K showed the highest photocatalytic activity and nitrate conversion reached 39.2% after 2 h irradiation. The enhanced effect for photocatalytic nitrate reduction activity was most likely to result from the formation of composite semiconductor MgTiO3-TiO2 and the transformation of TiO2 crystalline phase. [Copyright &y& Elsevier]

Titania supported palladium-copper bimetallic catalysts (Pd-Cu/TiO2) are prepared by the liquid phase chemical reduction method and then applied in the liquid phase catalytic reduction of nitrate ions (NO3−). Compared with the conventional impregnation method that needs the post-thermal reduction to prepare the supported metallic catalysts, the liquid phase chemical reduction at room temperature can inhibit the aggregation of metal active components and have been proved to exhibit high catalytic activity in this work. The conversions of NO3− are 29.18% and 54.12% over the catalysts treated at 873 and 298 K, respectively. The conversion of NO3− and selectivity to N2 influenced by the effect of the support, the loading of Pd+Cu, the molar ratio of Pd to Cu, the H2 flow rate, the addition of CO2 and the pH value of solution are also discussed in detail with the surface characterizations by X-ray photoelectron spectrum (XPS), X-ray diffraction (XRD), in situ FT-IR and transmission electron microscopy (TEM). A mechanism has been proposed that Cu2O component involved the reaction course and acted as the active center for nitrate-to-nitrite conversion. The spilt-over hydrogen on Pd is suggested to reduce the adjacent Cu2O into metal Cu, and on the latter the conversion of NO3− to NO2− occurs. However, in strongly acidic solution, copper is dissolved from the Pd-Cu/TiO2 catalyst and released into the solution in the form of copper(II) ions, so the reduction of Cu2O to Cu is inhibited and the nitrate reduction cannot be accomplished. [Copyright &y& Elsevier]

Titania-supported palladium–copper bimetallic catalysts (Pd–Cu/P25) are prepared by liquid-phase chemical reduction method and then applied in liquid-phase catalytic reduction of nitrite ions (NO2-). Compared with the conventional impregnation method, which usually needs a post-thermal reduction procedure to eliminate the introduced anions, liquid-phase chemical reduction at ambient temperature was proved to inhibit the aggregation of metal active components by means of TEM and DSC analysis in this work, and the catalyst exhibited superior catalytic activity. The conversion of nitrite reached a high level (1×10-4 mol min-1} gcat-1) and is about 14 times than that reported recently. The influences on the conversion of NO2- by support materials and the molar ratio of palladium to copper are also investigated, and further, the reaction mechanisms are discussed according to the characterization results of XPS and in situ FT-IR. [ABSTRACT FROM AUTHOR]

In this paper, we prove the relation v(t)⩽u(t,x)⩽w(t), where u(t,x) is the solution of an impulsive parabolic equations under Neumann boundary condition ∂u(t,x)/∂ν=0, and v(t) and w(t) are solutions of two impulsive ordinary equations. We also apply these estimates to investigate the asymptotic behavior of a model in the population dynamics, and it is shown that there exists a unique solution of the model which converges to the periodic solution of an impulsive ordinary equation asymptotically. [Copyright &y& Elsevier]

This paper studies wave propagation in functionally graded metal foam plates reinforced with graphene platelets (GPLs), where various types of porosity and GPL distribution are taken in account. The Halpin–Tsai model is employed to express the material properties of metal foam plates reinforced with GPLs. The governing equations of wave propagation in metal foam plates are derived by Hamilton's principle together with different plate theories, upon which wave dispersion relations in plates are achieved. Then, the validation of proposed model is examined by comparing the natural frequencies calculated in present study and those from literature. Finally, the effects of porosity and GPL distributions, porosity coefficient, GPL volume fraction and geometry on wave dispersion relations are evaluated. [ABSTRACT FROM AUTHOR]

Quantile regression (QR) for a groupwise additive multiple-index models and its applications are investigated. We find that quantile regression can be used to recovery the directions of the index parameter vectors, and it does not involve the nonparametric treatment completely. Based on this useful finding, a iterative-free QR estimator for the partial linear single index model and a penalized QR for variable selection in the high dimensional sparse models are proposed respectively. Because of inheriting the superiorities of quantile regression, our methods are robust and comprehensive. Simulation studies and real data analysis are included to illustrate the finite sample performance. [ABSTRACT FROM AUTHOR]

δ-BiB3O6 shows a comparable nonlinear optical performance with the famous α-BiB3O6. It can be prepared either by a high temperature-high pressure method or by a sol–gel method associated with RE3+-doping (RE = La, Ce, Pr, and Nd). A direct solid state reaction at 700 °C stabilized 20 atom% La3+ doped δ-BiB3O6 compared to the previously reported record (15 atom%) in the literature. La3+ doping would not only expand the thermodynamically stable region, which is critical for the synthesis, but also hasten the crystallization process. Moreover, Eu3+, a smaller RE cation, was also doped for the first time at a high doping level (7 atom%) simply by a seed-assisted solid state reaction, which apparently provides additional functionality and will prompt further efforts on single crystal growth of RE3+-doped δ-BiB3O6 under ambient pressure. The combined powder X-ray diffraction and transmission electron microscopy analysis underpinned the phase purity and doping homogeneity of cation doped bismuth borates. UV-excited red luminescence was observed for δ-Bi0.93Eu0.07B3O6. [ABSTRACT FROM AUTHOR]

The crystal structures, photoluminescence properties, and transport properties of a series of new "114" oxides CaBa1−xSrxZn2Al2O7 (x = 0–1) were investigated in detail. Careful Rietveld refinements performed on solid solution samples revealed that the structural symmetry of CaBa1−xSrxZn2Al2O7 evolves from hexagonal P63mc (x < 0.2) to trigonal P31c (0.2 ≤ x ≤ 0.6) and then to orthorhombic Pna21 (x > 0.6) with an increase of the Sr2+-content, which is cooperative with the rotation of T1O4 tetrahedra around the c-axis. Eu3+ was used as a local structural probe to gain an insight into the structure, which further corroborated the correctness of the observed structural symmetry descending sequence in CaBa1−xSrxZn2Al2O7. More importantly, the reduction of structural symmetry is also associated with a tendency from layered ordering to complete charge ordering transition for Zn2+/Al3+ cations, which was revealed to have a significant influence on the transport properties. These findings are expected to offer a route to manipulate the physical properties of "114" oxides containing magnetic cations. [ABSTRACT FROM AUTHOR]

It is important to develop red phosphors which can be efficiently excited by near ultraviolet (NUV) irradiation, matching the wavelength of commercial LED chips. ZnLaB 5 O 10 possesses a significantly distorted coordination of La3+ and suitable for the Eu3+ incorporation, whose parity-forbidden law could be suppressed in such a coordination and be efficiently excited by f - f transitions in the NUV range. ZnLa 1- x Eu x B 5 O 10 (0 ≤ x ≤ 1.0) were prepared by high temperature solid state reactions. Excitation and emission spectra prove that the concentration saturation occurs at a high Eu3+ concentration (∼60 atm%). All the phosphors emit the bright red light with a high red-to-orange ratio (2.7–3.1) and CIE coordinate (0.64, 0.36). In-situ high temperature photoluminescence spectra of ZnLa 0.4 Eu 0.6 B 5 O 10 prove its high thermal stability, i.e. the emission intensity at 150 °C remains 90% of the value at room temperature, thus being a suitable candidate for NUV-LED pumped red phosphor. ZnLa 1- x Eu x B 5 O 10 (0 ≤ x ≤ 1.0) were prepared by solid state reactions and the photoluminescence property was investigated systematically. Eu3+ locates at a 10-fold coordination environment with C 1 symmetry, thus the f - f transition at 393 nm is substantially intense and the emission quenching occurs at a high Eu3+ concentration (>60 atm%). The optimal sample ZnLa 0.4 Eu 0.6 B 5 O 10 together with commercial blue and green phosphors were combined with the 390 nm LED chip to emit a warm white light. Image 1 • ZnLa 1- x Eu x B 5 O 10 (0 ≤ x ≤ 1.0) were prepared by typical solid state reactions. • The concentration saturation occurs at a high Eu3+ concentration (∼60 atm%). • All samples emit the bright red light with a high red-to-orange ratio (2.7–3.1). • The emission intensity of ZnLa 0.4 Eu 0.6 B 5 O 10 at 150 °C remains 90%. • ZnLa 0.4 Eu 0.6 B 5 O 10 phosphor can be efficiently pumped by a 395 nm LED chip. [ABSTRACT FROM AUTHOR]

Six degree-of-freedom (6-DoF) visual tracking of dynamic objects is fundamental to a large variety of robotics and augmented reality (AR) applications. A key to this problem is accurate distance measurement of dynamic objects, which is usually obtained via stereo cameras, RGB-D sensors, or LiDARs. In this paper, however, we address the problem using only a monocular camera rigidly mounted with a low-cost inertial measurement unit. This is a light-weight, small-size, and low-cost solution, which is particularly suitable for tracking dynamic objects on drones or on mobile phones. Starting from a generic image-based two-dimensional tracker, we propose a novel method to resolve the object scale ambiguity in monocular vision in a geometric manner based on correlation analysis. This enables accurate metric three-dimensional tracking of arbitrary objects without requiring any prior knowledge about the object shape or size. We discuss the applicability by analyzing the observability condition and degenerated cases for object scale recovery. Simulation and real-world experimental results with ground truth comparison, along with AR application examples, demonstrate the feasibility of the proposed 6-DoF tracking method. [ABSTRACT FROM AUTHOR]

The structural template effect of H3BO3 in flux synthesis is discovered by preparing an open-framework gallium borate. [ABSTRACT FROM AUTHOR]

Rare-earth borates are good candidates for optical applications. To date, however, the high-pressure/high-temperature technique has produced a large number of novel borates with optical properties that have rarely been investigated due to the severe problem of substantial defects. We targeted the high-pressure polymorph of β-GdB3O6 and synthesized three solid solutions of β-Gd0.75− xBi0.25Tb xB3O6 (0≤ x≤0.75), β-Gd0.75− yBi0.25Eu yB3O6 (0≤ y≤0.75), and β-Gd0.50− zBi0.25Tb0.25Eu zB3O6 (0≤ z≤0.05) by using typical solid-state reactions at 820 °C. Here, the function of Bi3+ is to stabilize the high-pressure phase by lowering the synthetic temperature and being the sensitizer to promote the green and red emissions of Tb3+ and Eu3+. The multiple energy transfer paths were investigated by using lifetime decay experiments and photoluminescent spectra, and both efficiency and mechanism were determined. Eventually, color-tunable and white emissions were achieved by rational doping of Bi3+, Tb3+, and Eu3+ into β-GdB3O6, that is, the CIE chromaticity coordinate for β-Gd0.44Bi0.25Tb0.30Eu0.01B3O6 is (0.318, 0.365) with a correlated color temperature of 6101 K. [ABSTRACT FROM AUTHOR]

Metal borates are well-known optical materials while their semiconducting behavior, i.e. photocatalytic property, was less studied. Inspired by the recent publications on gallium borates with good photocatalytic performances, we investigated photocatalytic water reduction activity of another gallium borate, PbGaBO 4 , comprising edge-sharing GaO 6 -chains. Both conventional and solution assisted solid state reaction methods were employed for the preparation. Phase purity and the crystallinity of both samples were identified by powder X-ray diffraction and scanning electron microscopy. The UV–Vis reflectance spectra suggested the wide bandgap characteristic (4.10 eV) and theoretical calculations pointed out that the 6s and 5p orbitals of Pb 2+ contribute to both the bottom of CB and the top of VB. However the ionic bonding of Pb O in PbGaBO 4 led to a slight hydrolysis during the photocatalysis process, which can be suppressed by loading cocatalysts of Pt and RuO x . In addition, such a surficial modification significantly improved the photocatalytic water reduction ability, with an optimal H 2 evolution rate of 41.9(9) μmol/h/g under UV-light irradiation. [ABSTRACT FROM AUTHOR]

As a critical transformational process in the attributes of epithelial cells, epithelial-to-mesenchymal transition (EMT) is involved in tumor invasion, metastasis, and resistance to treatment, which contributes to the ultimate death of some patients with breast cancer. Glycogen synthase kinase-3-beta (GSK3β) is thought to be an EMT suppressor that down-regulates the protein, snail, a zinc finger transcription inhibitor, and regulates E-cadherin expression and the Wnt signaling pathway. Our previous studies have shown that Notch3 also inhibits EMT in breast cancer. In mammary gland cells, GSK3β physically bound and phosphorylated the intracellular domain of two Notch paralogs: N1ICD was positively regulated, but N2ICD was negatively regulated; however, the relationship between Notch3, GSK3β, and EMT in breast cancer is still unclear and crosstalk between Notch3 and GSK3β has not been widely investigated. In this study, we revealed that Notch3 was an essential antagonist of EMT in breast cancer cells by transcriptionally upregulating GSK3β. In breast cancer, MCF-7 and MDA-MB-231 cell lines, the silencing of Notch3 reduced GSK3β expression, which is sufficient to induce EMT. Conversely, ectopic Notch3 expression re-activated GSK3β and E-cadherin. Mechanistically, Notch3 can bind to the GSK3β promoter directly and activate GSK3β transcription. In human breast cancer samples, Notch3 expression is positively associated with GSK3β (r = 0.416, p = 0.001); moreover, high expressions of Notch3 and GSK3β mRNA are correlated to better relapse-free survival in all breast cancer patients via analysis in "the Kaplan–Meier plotter" database. In summary, our preliminary results suggested that Notch3 might inhibit EMT by trans-activating GSK3β in breast cancer cells. The suppression of Notch3 expression may contribute to EMT by transcriptionally downregulating GSK3β in breast cancer. [ABSTRACT FROM AUTHOR]

The study of perovskites has been active for a long time. Here, we rationally designed and prepared a double perovskite, LaBaZnSbO6, by selecting Zn2+ and Sb5+ with large size and charge differences, and, indeed, complete B-site ordering can be achieved. Careful study using powder X-ray diffraction data pinpointed its space group to be I2/m, which has rarely been seen in double perovskites. Thereafter, an interesting observation of Sr2+-doping-induced symmetry evolution from I2/m to P21/n was confirmed in the complete solid solutions LaBa1−xSrxZnSbO6, where the tilting system also transferred from a−a−c0 to a−a−c+. The transition boundary is around x = 0.4. It can also be visualized by the variation of ϑ (defined as c/[(a + b)/2]), which is associated with the anisotropic shrinkage of the unit cell lattice and indeed shows a minimum at x = 0.4. Such a successive modulation of both the structural symmetry and the average La/Ba/Sr–O bond distances (revealed by Rietveld refinements) motivated us to study the Eu3+ luminescence in La0.95Eu0.05Ba1−xSrxZnSbO6. Interestingly, the maximum of charge transfer absorption of Eu3+ shows a precise changing tendency with the A–O bond distances along with the Sr2+ doping, clearly revealing the structure–luminescence correlations. [ABSTRACT FROM AUTHOR]

Extensive studies on photoluminescence (PL) were devoted to the well-known “ RE BaB 9 O 16 ” family, while the structure remained unsolved until the recent work on the structure determination of its new analogue Ba 6 Bi 9 B 79 O 138 . Accordingly, a re-visit to “ RE BaB 9 O 16 ” with the new formula was rationally performed by the syntheses and Tb 3+ -PL study on Ba 6 La 9 B 79 O 138 ( BLBO ) and Ba 6 Y 9 B 79 O 138 ( BYBO ). Powder XRD patterns of Ba 6 ( RE 1− x Tb x ) 9 B 79 O 138 ( RE = La and Y, 0 ≤ x ≤ 1) show a linear shrinkage or expansion of the unit cell in BLBO : x Tb 3+ and BYBO : x Tb 3+ , respectively. The ratio of Tb 3+ cyan/green (C/G) emission was proposed to evaluate the evolution principle of the RE -site symmetry in both series of phosphors. The C/G value remains unchanged in BLBO : x Tb 3+ , while it is sensitive to the Tb 3+ -to-Y 3+ substitution in BYBO : x Tb 3+ . For example, C/G keeps almost constant (∼0.30) when 0.10 ≤ x ≤ 0.5; a dramatic increase of C/G (from 0.33 to 0.67) occurs in the range of 0.50 ≤ x ≤ 0.90, accompanied with a RE -site symmetry transition from centrosymmetric to noncentrosymmetric; the value of C/G remains unchanged thereafter. The Ce 3+ -to-Tb 3+ sensitization effect is applied in Ba 6 ( RE 0.3− y Ce y Tb 0.7 ) 9 B 79 O 138 ( RE = La or Y, 0 ≤ y ≤ 0.3), and the samples with y = 0.2 possess the strongest green emission. [ABSTRACT FROM AUTHOR]

We present a systematic investigation on the photocatalytic ability of an open-framework gallium borate, Ga-PKU-1. It was reported to be intrinsically active for water reduction or oxidation, however, acquiring sacrificial reagents. Here the loading of CoO x , RuO x , Pt, Au, NiO x and Ag as cocatalysts greatly enhanced the catalytic activity, which eventually lead to overall water splitting into stoichiometric H 2 (28.4 μmol/h/g) and O 2 (14.5 μmol/h/g) for 1 wt.% RuO x –1 wt.% Pt loaded Ga-PKU-1. After three cycles of photocatalytic water splitting experiments, it gave the constant H 2 evolution rate with no degradation of the catalyst. [ABSTRACT FROM AUTHOR]

Borates are well-known candidates for optical materials and, here, we are particularly interested in Ba6Bi9B79O138 (BBBO), which has an interesting layered-type structure and Bi3+-containing characteristics that has prompt us to explore its host-sensitized photoluminescence (PL). Solid solutions of BBBO: xTb3+ (0 ≤ x ≤ 1) were prepared and its host-sensitized photoluminescence was confirmed, which is a result of the efficient Bi3+-to-Tb3+ energy transfer. Furthermore, an evolution of the coordination environments of the Bi3+/Tb3+ sites was observed when increasing x. This evolution was found to correlate to the variation of the PL spectra. In particular, the value of the ratio of cyan/green [defined as I(5D4→7F6)/ I(5D4→7F5) of Tb3+] was about 0.28 when x < 0.4, and it increased to 0.71 at x = 0.9 and thereafter remained almost constant. Ba6(RE0.3- yBi yTb0.7)9B79O138 (RE = La or Y, 0 ≤ y ≤ 0.3) were also prepared for better understanding of the host-sensitization effect and in both series, Ba6(RE0.1Bi0.2Tb0.7)9B79O138 show the highest emission. [ABSTRACT FROM AUTHOR]

Tb 3+ -substituted SrWO 4 Scheelite compounds are well-known green phosphors. Herein this work, we prepared three partial solid state solutions of Sr 1−1.5 x Tb x □ 0.5 x WO 4 (□ = vacancy, 0.01 ⩽ x ⩽ 0.24) and Sr 0.64− y Tb 0.24 Li 2 y □ 0.12− y WO 4 (0 ⩽ y ⩽ 0.12) and Sr 0.70−2 z Tb 0.20+ z Li z □ 0.10 WO 4 (0 ⩽ z ⩽ 0.10). Rietveld refinements on selected samples were performed to confirm the existence of A -site vacancies. In addition, the continuous variation of either Tb 3+ or vacancy concentrations offers an opportunity to study the structure–property correlation. A decrease of Sr–O average distance and an elongation of W–O bond length were detected in Sr 1-1.5 x Tb x □ 0.5 x WO 4 , which result in a slight red-shifting of WO 4 2− CT absorption band. The optimal concentration for green emission of Sr 1−1.5 x Tb x □ 0.5 x WO 4 (0.01 ⩽ x ⩽ 0.24) was found to be 0.12. The occurrence of concentration quenching effect is not only due to the increase of the Tb 3+ concentration, vacancies in the structure also play an important role. With Li + -co-doping, the emission shows a great enhancement not only due to the modification of the A -site coordination but also the diminishing of the A -site vacancy. [ABSTRACT FROM AUTHOR]

Distributed penalized generalized linear regression algorithms have been widely studied in recent years. However, they all assume that the data should be randomly distributed. In real applications, this assumption is not necessarily true, since the whole data are often stored in a non-random manner. To tackle this issue, a non-convex penalized distributed pilot sample surrogate negative log-likelihood learning procedure is developed, which can realize distributed high-dimensional variable selection for generalized linear models, and be adaptive to the non-random situations. The established theoretical results and numerical studies all validate the proposed method. [ABSTRACT FROM AUTHOR]

Significant oxide-ionic conductivity has been recently reported for a family of cation-deficient hexagonal perovskite derivatives Ba3M2O8.5 (M = Mo/W6+ and Nb5+/V5+). Herein, strong 4-fold coordination geometry preferring Ge4+ ions are doped into Ba3Mo1+xNb1−2xGexO8.5 to manipulate the oxygen distribution within palmierite-like layers for the enhancement of oxide-ionic conductivity. Rietveld refinement of the neutron diffraction data of Ba3Mo1.2Nb0.6Ge0.2O8.5 reveals that Ge4+-ions are selectively incorporated into the palmierite-like layers, owing to their strong 4-fold coordination environment preference. Such a site-selective doping behavior leads to an increase in the occupation proportion of the O3 site and a concomitant decrease in the occupancy factor for O2. Ionic conduction measurements show that the bulk conductivity of Ba3Mo1.2Nb0.6Ge0.2O8.5 is about twice higher than that of the parent compound at intermediate temperatures (300–500 °C). Furthermore, bond-valence site energy (BVSE) landscape analysis reveals that the oxygen ionic conduction of Ba3Mo1+xNb1−2xGexO8.5 is dominated by the two-dimensional pathways along the palmierite-like layers, despite the three-dimensional (3D) oxygen diffusion pathways being present in the hybrid structure, which strongly confirms that the enhancement in ionic conductivity at intermediate temperatures is attributed to the site-selective Ge4+-substitution-induced redistribution of oxygen ions within the palmierite-like layers. [ABSTRACT FROM AUTHOR]

Abstract: Three new borates MB12O14(OH)10 (M=Mn, Fe, Zn) have been synthesized by boric acid flux methods, which are isotypic to NiB12O14(OH)10. Single-crystal XRD was performed to determine the crystal structures in detail. They all crystallize in the monoclinic space group P21/c. The size of MO6 (M=Mg, Mn, Fe, Co, Ni, Zn) octahedron shows a good agreement with the Shannon effective ionic radii of M2+. Magnetic measurements indicate MnB12O14(OH)10 is antiferromagnetic without a long-range ordering down to 2K. The values of its magnetic superexchange constants were evaluated by DFT calculations, which explain the observed magnetic behavior. The UV–vis diffuse reflectance spectrum of ZnB12O14(OH)10 suggests a band gap ∼4.6eV. DFT calculations indicate it has a direct band gap 4.9eV. The optical band gap is contributed by charge transfers from the occupied O 2p to the unoccupied Zn 4s states. [Copyright &y& Elsevier]

Clustering analysis is one of the most important technologies for single-cell data mining. It is widely used in the division of different gene sequences, the identification of functional genes, and the detection of new cell types. Although the traditional unsupervised clustering method does not require label data, the distribution of the original data, the setting of hyperparameters, and other factors all affect the effectiveness of the clustering algorithm. While in some cases the type of some cells is known, it is hoped to achieve high accuracy if the prior information about those cells is utilized sufficiently. In this study, we propose SCMAG (a semisupervised single-cell clustering method based on a matrix aggregation graph convolutional neural network) that takes into full consideration the prior information for single-cell data. To evaluate the performance of the proposed semisupervised clustering method, we test on different single-cell datasets and compare with the current semisupervised clustering algorithm in recognizing cell types on various real scRNA-seq data; the results show that it is a more accurate and significant model. [ABSTRACT FROM AUTHOR]

Recently, broad-band white-light-emitting using Eu2+, Ce3+, or Bi3+ in multi-sites of a single-phase phosphor have drawn extensive attention due to their potential to realize high-quality indoor lighting. This work reports a novel oxide, Ca7Mg2Ga6O18 (CMG), possessing a complex crystal structure in the space group F432. Rietveld refinements of high-resolution synchrotron X-ray diffraction data were performed to determine the accurate atomic positions and occupancy factors, giving a reasonable composition of Ca7Mg1.91(4)Ga6.09(4)O18. Due to the multiple sites of Ca2+, which are suitable for the doping of Bi3+ activators, CMG is a promising host to achieve broad-band white-light emission. Detailed structural and spectroscopic analyses revealed that the Bi3+-activator shows multiple and site-selective occupancy, which is the origin of the red-shifts in both broad-band excitation and emission spectra upon increasing the Bi3+ content. A series of Bi3+ and Eu3+ codoped phosphors with tunable blue-pink-red emission were prepared due to the Bi3+-to-Eu3+ energy transfer. Due to the distinctive thermal behaviors of Bi3+ and Eu3+ emissions, CMG:Bi3+,Eu3+ is a candidate for optical thermometry. [ABSTRACT FROM AUTHOR]

We performed a facile and organic-free hydrothermal method (thiourea-oxalic acid co-molten system) to prepare chalcopyrite CuInS 2 nano-crystallite. Its intrinsic photocatalytic activities to nitrate reduction in aqueous solutions were investigated in comparison to bulk CuInS 2 prepared by annealing Cu 2 S and In 2 S 3 at 600–750 °C under vacuum. All samples show good and similar photocatalytic activities for nitrate reduction, for example, the conversion rate is about two times of that in a blank experiment. All CuInS 2 catalysts were stable after the photocatalytic reactions, indicated by the identical XRD patterns before and after the reaction. [ABSTRACT FROM AUTHOR]

Selective gas adsorption and separation were intensively investigated for porous materials like metal-organic frameworks (MOFs) and Zeolites. In this study, an intrinsically microporous aluminoborate, PKU-2, with an extra-large one dimensional channel (~9.6 Å) was discovered for the first time to exhibit selective CO 2 and C 2 H 2 adsorption over CH 4 and C 2 H 4 , respectively. Incorporation of Cr3+ and Fe3+ ions into the framework could effectively enlarge the specific surface area in comparison with the pristine PKU-2, which is accompanied with a significant enhancement of gas adsorption capacities for CO 2 and C 2 H 2 to 3.9 and 2.86 mmol/g, respectively, for Fe-PKU-2, and a slight decrease of gas separation selectivities. The high gas adsorption capacities and selectivities together with their high thermal stability imply their potential practice applications for environment and energy-relevant gas adsorption and separation. In addition to MOFs and zeolites, the microporous aluminoborate PKU-2 with an extra-large one dimensional channel exhibits highly selective CO 2 and C 2 H 2 adsorptions over N 2 /CH 4 and C 2 H 4 , respectively, at 293 K. Image 1 • Microporous aluminoborate (PKU-2) was synthesized by boric acid flux method. • High CO 2 and C 2 H 2 adsorption capacities at 293 K were observed for PKU-2. • PKU-2 exhibits selective CO 2 and C 2 H 2 adsorption over CH 4 and C 2 H 4 , respectively. • PKU-2 is the first aluminoborate that exhibits selective gas adsorption. • Enhancement of gas adsorption performances were achieved by transition metal doping. [ABSTRACT FROM AUTHOR]

The high-pressure polymorph of β-YB 3 O 6 was stabilized by doping Bi3+ under ambient pressure, thus solid solutions of β-Y 1- m Bi m B 3 O 6 (0.10 ≤ m ≤ 0.30), β-Y 0.80- x Bi 0.20 Tb x B 3 O 6 (0.05 ≤ x ≤ 0.80), and β-Y 0.80- y Bi 0.20 Eu y B 3 O 6 (0.05 ≤ y ≤ 0.80) were prepared simply by high temperature solid state reactions. The phase purity and the successful cationic substitutions were confirmed by powder X-ray diffraction, where the linear expansion of lattice parameters was observed due to the replacement of Y3+ by lager cations. The second function of Bi3+ was to behave as a photoluminescent activator giving the blue emission, as well as a sensitizer to Tb3+ and Eu3+, which emit green and red light, respectively. Bright and color-tunable emissions from blue to green (or blue to red) were achieved by manipulating the relative ratio between Bi3+ and Tb3+ (or Eu3+). In final, a white emission was observed for the triply-doped phosphor β-Y 0.49 Bi 0.20 Tb 0.30 Eu 0.01 B 3 O 6. Since the highly efficient energy transfers from Bi3+ to Tb3+ and from Bi3+ to Eu3+, color-tunable emissions from blue to green and from blue to red can be achieved in Bi3+/Tb3+ and Bi3+/Eu3+ co-doped β-YB 3 O 6 , which is originally a high-pressure polymorph and could be stabilized at ambient pressure due to the Bi3+ substitutions. Image 1 • The high-pressure phase β-YB 3 O 6 was stabilized at ambient pressure by doping Bi3+. • Bi3+ emits the blue light and the optimal doping concentration is 20 atom%. • Bi3+, Tb3+, Eu3+ co-doped and triply-doped β-YB 3 O 6 were prepared. • Highly efficient energy transfer from Bi3+ to Tb3+/Eu3+ was proved. • Bright color-tunable emissions from blue to green (or blue to red) were achieved. [ABSTRACT FROM AUTHOR]

Strecker reactions have an important application in the preparation of α-amino acids and biologically active molecules in homogeneous acid- or base-catalyzed systems. As novel solid acid catalysts, AlxGa1−x-PKU-1 (x = 0–1) solid solutions constructed by two octahedron-based molecular sieves were prepared by using a molten boric acid method and exhibited a continuously-adjustable acidity in heterogeneously-catalyzed Strecker reactions under mild conditions. AlxGa1−x-PKU-1 accommodated a large number of Brønsted acid sites in the framework, and the acidic density and strength were enhanced with the successive incorporation of Al atoms, thus the catalytic activity became superior in the formation of α-aminonitriles. Three-fold coordinated boron atoms, despite the electron-deficient configuration, seemed unable to behave as Lewis acid centers probably due to steric hindrance against the adsorption of large organic substrates. This work illustrates, for the first time, possible application in Strecker reactions using zeolite-like solid solutions, and will potentially provide an effective method and a beneficial reference to control surface acidity for porous materials. [ABSTRACT FROM AUTHOR]

Completed solid solutions of Y 1- x Eu x [B 6 O 9 (OH) 3 ] were prepared by boric acid flux method and the structure of Eu[B 6 O 9 (OH) 3 ] was determined by single crystal X-ray diffraction (XRD). The successful cationic doping was supported by the linear change of unit cell parameters obtained by Le Bail fitting on powder XRD. Thermal treatments on Y 1- x Eu x [B 6 O 9 (OH) 3 ] will lead to the dehydration, re-crystallization into TD-α-Y 1- x Eu x B 5 O 9 , and decomposition to α-Y 1- x Eu x B 3 O 6 eventually. For comparison, the sol-gel method was also applied to prepare SG-α-Y 1- x Eu x B 5 O 9. Rietveld refinements on powder XRD was applied to obtain the crystallographic data for α-YB 5 O 9. PL investigation indicated that the existence of hydroxyl groups weakened the Eu3+ charge transfer (CT) in Y 1- x Eu x [B 6 O 9 (OH) 3 ]. In α-Y 1- x Eu x B 5 O 9 , an intense CT absorption was detected and a bright right emission was observed. Moreover, both series of phosphors exhibited a right shift of CT maximum wavelength due to the expansion of unit cell and the delayed concentration at x = 0.6. Complete solid solutions of α-Y 1- x Eu x B 5 O 9 were prepared by either heating the precursors Y 1- x Eu x [B 6 O 9 (OH) 3 ] or direct sol-gel method, and the purity of the borates were verified by careful analyses on powder XRD. Detailed photoluminescence property investigation proved that α-Y 1- x Eu x B 5 O 9 are good red phosphors with a delayed concentration quenching at x = 0.6. Image 1 • Y 1- x Eu x [B 6 O 9 (OH) 3 ] (0 ≤ x ≤ 1) were prepared by boric acid flux method. • Heating Y 1- x Eu x [B 6 O 9 (OH) 3 ] at 670 °C led to the formation of TD-α-Y 1- x Eu x B 5 O 9. • Sol-gel method was also applied to synthesize SG-α-Y 1- x Eu x B 5 O 9. • The CT transition of Eu3+ in Y 1- x Eu x [B 6 O 9 (OH) 3 ] was weakened by hydroxyl groups. • α-Y 1- x Eu x B 5 O 9 have a bright red emission and a concentration quenching at x = 0.6. [ABSTRACT FROM AUTHOR]