The defects can greatly promote the catalytic activity of the carbon-based electrocatalyst due to charge redistribution of the electroneutral π-conjugated structure. However, it is still a huge challenge to introduce...

We consider the hypothesis testing problem that two vertices i and j of a generalized random dot product graph have the same latent positions, possibly up to scaling. Special cases of this hypotheses test include testing whether two vertices in a stochastic block model or degree-corrected stochastic block model graph have the same block membership vectors. We propose several test statistics based on the empirical Mahalanobis distances between the ith and jth rows of either the adjacency or the normalized Laplacian spectral embedding of the graph. We show that, under mild conditions, these test statistics have limiting chi-square distributions under both the null and local alternative hypothesis, and we derived explicit expressions for the non-centrality parameters under the local alternative. Using these limit results, we address the model selection problem of choosing between the standard stochastic block model and its degree-corrected variant. The effectiveness of our proposed tests are illustrated via both simulation studies and real data applications.

Novel 3D metal formate frameworks {[Ba4Cl]­[M3(HCO2)13]} n (M = Mn for 1, Co for 2, and Mg for 3) were successfully assembled via microwave-assisted synthesis. The complexes are rare coordination polymers crystallized at space group P4cc with the polar point group C 4v . In the structure, the MII ions are bridged by two types of anti-anti formate in forming a 3D pcu framework, and additional formates coordinate to the unsaturated sites of the MII ions in the framework, giving an anionic M–formate net. Ba4Cl clusters take the cavities of the net as charge balance, in which the chloride ion deviates from the center of the barium ions. The asymmetric Ba4Cl structure is transmitted throughout the crystal resulting in polar structure, which is further confirmed by nonlinear optical and piezoelectric test. Nonlinear optical activity tests of 1 and 3 show SHG signals 0.32 and 0.28 times that of KDP, while 2 has a piezoelectric coefficient d 33 of 6.8 pC/N along polar axis. Magnetic studies reveal antiferromagnetic coupling between MII ions in 1 and 2. Spin canting was found only in 2 with anisotropic CoII ions, and 2 is a canted antiferromagnetically with T N = 5 K. Further field-induced spin flop was also found in 2 with a critical field 0.9 T.

The strength of the natural gas transmission pipe is reduced due to sag deformation and corrosion defects. However, there are rare experiment data to quantitatively describe the effect of the defect’s size and position on the pipe strength. This paper designed seven groups of steel pipes with various defects to perform the hydrostatic bursting experiments, and to research the effects of the defects on the strength of the steel pipe. The experimental pipe sample is selected as the X52 material. Three types of defects were set up: concave and corrosion combinational defects, one corrosion defect, and two corrosion defects. The pipe rupture size, the strain around defects, and pipe perimeters before and after experiments are measured, finally yielding the strain-pressure curve of each steel pipe. Comparisons of experimental results show that the defect depth is the dominant factor affecting the pipe strength. Moreover, results show that the DNV-RP-F101 code tends to yield less distance beyond which two defects will not affect each other. The ASME B31G code also tends to give a lower residual strength of the pipe. However, in comparison with the PCORRC criterion, the ASME B31G formula has higher accuracy for X52 pipes. The average relative deviation between the experimental and calculated corroded pipe strength is 14.87%.

In this work, we report two multi-component MOFs [CH3NH2CH3]2[FeIII2MII10(tz)11(HCO2)12(btc)5/3] (MII10 = FeII10 for 1 and MII10 = FeII2CoII8 for 2) obtained by solvothermal assembling formate, benzene-1,3,5-tricarboxylate (btc) and 1,2,4 triazole...