Crystal growth, structure and thermal properties of noncentrosymmetric single crystals PrCa4O(BO3)3+

Noncentrosymmetric praseodymium calcium oxyborate single crystals, PrCa4O(BO3)3 (PrCOB), were grown by the Czochralski technique. The monoclinic unit cell parameters were found to be a = 8.177 Å, b = 16.157 Å, c = 3.629 Å and Z = 2 with space group Cm. Crystal density was measured using the Archimedes method, being on the order of 3.47 g cm-3. Thermal properties of PrCOB were investigated, where the specific heat was found to be 0.63 J g-1 °C-1 at room temperature, increasing to 0.85 J g-1°C-1 at 700°C. The thermal expansion coefficients were measured to be α11 = 7.99, α22 = 4.90 and α33 = 9.46 (10-6/°C), respectively. In addition, thermal diffusivity λ22 and thermal conductivity κ22 as a function of temperature were studied, where λ22 was observed to decrease from 0.89 to 0.58 mm2 s-1, while κ22 was found to maintain the same value, being ∼1.90 W m-1°C-1 over the temperature range of 20-700°C. 2013 The Royal Society of Chemistry

Bioinformatics-based analysis of the roles of basement membrane-related gene AGRN in systemic lupus erythematosus and pan-cancer development

IntroductionSystemic lupus erythematosus (SLE) is an autoimmune disease involving many systems and organs, and individuals with SLE exhibit unique cancer risk characteristics. The significance of the basement membrane (BM) in the occurrence and progression of human autoimmune diseases and tumors has been established through research. However, the roles of BM-related genes and their protein expression mechanisms in the pathogenesis of SLE and pan-cancer development has not been elucidated.MethodsIn this study, we applied bioinformatics methods to perform differential expression analysis of BM-related genes in datasets from SLE patients. We utilized LASSO logistic regression, SVM-RFE, and RandomForest to screen for feature genes and construct a diagnosis model for SLE. In order to attain a comprehensive comprehension of the biological functionalities of the feature genes, we conducted GSEA analysis, ROC analysis, and computed levels of immune cell infiltration. Finally, we sourced pan-cancer expression profiles from the TCGA and GTEx databases and performed pan-cancer analysis.ResultsWe screened six feature genes (AGRN, PHF13, SPOCK2, TGFBI, COL4A3, and COLQ) to construct an SLE diagnostic model. Immune infiltration analysis showed a significant correlation between AGRN and immune cell functions such as parainflammation and type I IFN response. After further gene expression validation, we finally selected AGRN for pan-cancer analysis. The results showed that AGRN’s expression level varied according to distinct tumor types and was closely correlated with some tumor patients’ prognosis, immune cell infiltration, and other indicators.DiscussionIn conclusion, BM-related genes play a pivotal role in the pathogenesis of SLE, and AGRN shows immense promise as a target in SLE and the progression of multiple tumors

Electrical properties of yttrium calcium oxyborate crystal annealed at high temperature and low oxygen partial pressure

The yttrium calcium oxyborate crystal (YCa 4 O(BO 3 ) 3 , YCOB) has been actively studied for high-temperature piezoelectric sensing applications. In this work, the stability of electric properties of YCOB crystal annealed in critical conditions (high-temperatures of 900-1100 °C with a low oxygen partial pressure of 4 x 10 −6 atm for 24 h) was investigated and the recovery mechanism for the electrical resisitivity, dielectric permittivity and dielectric loss were studied, taking advantage of the X-ray photoelectron spectra and the first principle calculations. The electrical resistivity of the annealed YCOB crystal was slightly decreased when compared to the pristine counterpart, being (2-5) x 10 7 Ω cm at 850 °C. The dielectric permittivity and dielectric loss were found to increase after annealing, showing recoverable behaviours after thermal treatment above 650 °C in air. The calculated vacancy formation energy indicate that the oxygen vacancy is the dominant defects in YCOB. The formation of oxygen vacancy weakens the chemical bonding strength between B (Ca or Y) and O atoms, introduces extra donor levels in the band gap, which excites the electrons to conduction band more easily thus enhances the electrical conductivity and dielectric loss. The recovered electrical properties are believed to be associated with the reduced vacancy defects at elevated temperatures in air

Crystal growth, structure and thermal properties of noncentrosymmetric single crystals PrCa4O(BO3)3

Noncentrosymmetric praseodymium calcium oxyborate single crystals, PrCa4O(BO3)3 (PrCOB), were grown by the Czochralski technique. The monoclinic unit cell parameters were found to be a = 8.177 Å, b = 16.157 Å, c = 3.629 Å and Z = 2 with space group Cm. Crystal density was measured using the Archimedes method, being on the order of 3.47 g cm-3. Thermal properties of PrCOB were investigated, where the specific heat was found to be 0.63 J g-1 °C-1 at room temperature, increasing to 0.85 J g-1°C-1 at 700°C. The thermal expansion coefficients were measured to be α11 = 7.99, α22 = 4.90 and α33 = 9.46 (10-6/°C), respectively. In addition, thermal diffusivity λ22 and thermal conductivity κ22 as a function of temperature were studied, where λ22 was observed to decrease from 0.89 to 0.58 mm2 s-1, while κ22 was found to maintain the same value, being ∼1.90 W m-1°C-1 over the temperature range of 20-700°C. 2013 The Royal Society of Chemistry

Growth, Structure and Optical Characterization of Rb3Ti3P5O20 Single Crystal

Phosphate crystals attract much attention on account of their rich crystal structures and excellent physical and chemical properties. Herein, Rb3Ti3P5O20 single crystals were grown by the high temperature solution method using Rb2CO3 and NH4H2PO4 as the fluxes. This crystal, with non-centrosymmetric Pca21 space group, presents a three-dimensional framework structure composed of [TiO6] octahedron, [PO4] tetrahedra, and [P2O7] dimers. The electronic structure was measured via X-ray photoelectron spectroscopy. The measurements found that Rb3Ti3P5O20 has stronger Ti–O ionic bonding properties and weaker P–O covalent bonding properties compared to RbTiOPO4. Optical measurements indicated that Rb3Ti3P5O20 has a 3.54 eV band gap and a wide transmission range (0.33–4.5 μm). Theoretical calculations showed that Rb3Ti3P5O20 crystals have a moderate birefringence of 0.079 at 1064 nm. In addition, the relationship of the structure–property was studied using first-principles method. The results demonstrated that TiO6 octahedron played a significant role for the optical properties

The Local and Electronic Structure Study of Lu<i>_x</i>Gd_1−<i>x</i>VO₄ (0 ≤ <i>x</i> ≤ 1) Solid Solution Nanocrystals

Rare-earth-doped mixed crystals have demonstrated tunable optical properties, and it is of great importance to study the structural characteristics of the mixed-crystal hosts. Herein, LuxGd1-xVO4 (0 ≤ x ≤ 1) solid solution nanocrystals were synthesized by a modified sol–gel method, with a pure crystalline phase and element composition. The X-ray diffraction (XRD) and Rietveld refinement results showed that LuxGd1−xVO4 nanocrystals are continuous solid solutions with a tetragonal zircon phase (space group I41/amd) and the lattice parameters strictly follow Vegard’s law. The detailed local structures were studied by extended X-ray absorption fine structure (EXAFS) spectra, which revealed that the average bond length of Gd-O fluctuates and decreases, while the average bond length of Lu-O gradually decreases with the increase in Lu content. Furthermore, the binding energy differences of core levels indicate that the covalent V-O bond is relatively stable, while the ionicity of the Lu-O bond decreases with the increasing x value, and the ionicity of the Gd-O bond fluctuates with small amplitude. The valence band structures were further confirmed by the first-principles calculations, indicating that the valence band is contributed to by the O 2p nonbonding state, localized Gd 4f and Lu 4f states, and the hybridized states between the bonding O 2p and V 3d. The binding energies of the Lu core and the valence levels tend to decrease gradually with the increase in Lu content. This work provides insight into the structural features of mixed-crystal hosts, which have been developed in recent years to improve laser performance by providing different positions for active ions to obtain inhomogeneous broadening spectra

Characterization of LuGdVO3 mixed crystal prepared by one new method

LuGdVO3 was obtained by annealing the LuGdVO4 crystal at 1500 °C under vacuum condition. The X-ray fluorescence analysis method was used to measure the concentrations of Lu and Gd elements in LuGdVO4. The XRD result indicated that LuGdVO3 was the orthorhombic structure with space group Pbnm. The Raman spectrum of LuGdVO3 was investigated at room temperature. The chemical states and local symmetry of the LuGdVO3 crystal have been determined by XPS and XANES. It was found that the presence of different chemical forms of V evolved with annealing treatment, and the VO6 unit in the LuGdVO3 crystal was distorted octahedron. During the annealing process at high temperature under vacuum condition LuGdVO4 can be gradually translated to LuGdVO3 with decreasing lattice oxygen in the crystal lattice. Keywords: Lu0.5Gd0.5VO3 crystal, Annealing, XPS, XANE

Investigation of the dielectric and piezoelectric properties of ReCa4O(BO3)3 crystals

Piezoelectric ReCa4O(BO3)3 (ReCOB, Re: rare earth) crystals, including ErCOB, SmCOB, PrCOB and LaCOB, were successfully grown by the Czochralski (Cz) method. The dielectric constants were determined to be ε11 T/ε0 = 9.50, ε22 T/ε0 = 11.8 and ε33 T/ε0 =9.80 for ErCOB, ε11 T/ε0 = 9.70, ε 22 T/ε0 = 13.9 and ε33 T/ε0 = 9.90 for SmCOB, ε11 T/ε0 = 9.60, ε22 T/ ε0 = 15.3 and ε33 T/ε0 = 10.0 for PrCOB, ε11 T/ε0 = 9.40, ε22 T/ε0 = 15.0 and ε33 T/ε0 = 9.60 for LaCOB, respectively. The electromechanical coupling factors k26 and piezoelectric coefficients d26 were found to be 18.5% (7.6 pC N -1), 27.0% (12.7 pC N-1), 31.5% (15.8 pC N-1) and 25.0% (11.8 pC N-1) for ErCOB, SmCOB, PrCOB and LaCOB crystals, respectively. The dielectric and piezoelectric properties as a function of Re3+ ion radius were studied, with maximum values being observed in the PrCOB crystals, due to the similar ion radius of Pr3+ and Ca 2+. The relationship between the structure and dielectric/ piezoelectric properties of ReCOB crystals was explored, to further optimize the dielectric and piezoelectric properties in ReCOB series crystals. 2011 IOP Publishing Ltd

Temperature dependence of the electro-elastic properties of the monoclinic α-BiB3O6crystals

The monoclinic α-BiB3O6 (α-BIBO) crystal has been actively studied for nonlinear optical applications, but with limited efforts for piezoelectric usages. In this work, the temperature dependence of the electro-elastic properties for α-BIBO crystal was investigated over the temperature range of −150-150 °C, where the α-BIBO crystal was found to possess low dielectric loss (\u3c0.5%) and minimal variation of relative dielectric permittivities (\u3c±10%). The temperature coefficients of elastic compliances were obtained to be on the order of 0.2-5.1 x 10−4/°C. Moreover, the α-BIBO crystal was determined to own good temperature stability of electromechanical properties, with coupling factors being 13-32.1% at room temperature, while the independent piezoelectric coefficients shifted differently as a function of temperature with the first order temperature coefficients evaluated to be on the order of −0.3-17.9 x 10−4/°C. The above temperature characteristics of the electro-elastic properties are important for designing piezoelectric sensors operational over a broad temperature range