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In the progress of realizing the commercialization of organic optoelectronic materials, the four basic coherent factors are stability, cost, performance, and processability, all which determine the results of device applications. Spiro[fluorene-9,9′-xanthene] (SFX) has been becoming the robust building-block that fulfilling the practical requirements due to its key features of non-planarity, one-pot facile availability, well-defined quality assurance as well as performance behaviors. In this review, we introduce the SFX and its analogues, including synthesis, molecular design, device performance, and structure-property relationship, in the applications of organic light-emitting diodes (OLEDs), organic photovoltaics, perovskite solar cells (PSCs) and others. Furthermore, emitters or hosts for OLED and hole transport materials for PSCs are highlighted at the level of molecular configuration and film morphology. Tracing the thread from intrinsic photoelectric properties, molecular packing to optoelectronic application, the advantage of stability and low-cost of SFX-based materials are illuminated, and an outlook is given providing orientation for bring SFX into the fields of catalysis and energy chemistry in view of its binary conjugation and three-dimensional configuration.

A rigorous analytical solution is developed for undrained cavity expansion problems in non-associated Mohr–Coulomb soil, based on a novel graphical analysis approach and on the Lagrangian description through tracking only the responses of a soil particle at the cavity surface. The mathematical difficulties involved with the flow rate calculation when the stress state lies on the corner/edge of two adjacent (Mohr–Coulomb) yield surfaces, for both cylindrical and spherical cases, are tackled by using the generalised Koiter theory for non-associated plasticity. In particular, through the unique geometrical formulation, the effective stress path pertaining to the cylindrical cavity problem can be very conveniently directly determined, and is found to consist of simple, piecewise straight lines in the deviatoric stress plane with the orientations dependent of the relative magnitude of Poisson's ratio and the friction angle. This thus renders possible the removal of the stringent intermediacy assumption for the vertical stress that is commonly adopted in previous formulations, and hence the development of a complete cylindrical cavity expansion solution in Mohr–Coulomb soil under undrained loading conditions. The stress and deformation responses of the cavity, including the typical pressure–expansion curves and limiting cavity pressure, are finally analytically obtained along with the Lagrangian form of the radial equilibrium equation in completely explicit forms. The closed-form solution provided in this paper is the first rigorous one of its kind, thus completing the analytical analysis of the cavity expansion problem with the classical Mohr–Coulomb model; this is deemed to be essential for the interpretation of in situ test results pertaining to cohesive-frictional soils. [ABSTRACT FROM AUTHOR]

An analytical solution is presented for spherically symmetric growth of a fluid-saturated, poroelastic inhomogeneity inclusion embedded within a compressible elastoplastic matrix. A fluid source at the center causes the inclusion growth. The solution considers full poroelastic coupling of the inclusion pore fluid flow and solid phase deformation while solving for large deformation of the matrix via incremental elastoplasticity with associated flow rule and modified Mohr-Coulomb or Drucker-Prager yield models. Results obtained from the compressible (drained) solution are compared against the previously published solution pertaining to incompressible (undrained) matrix. Drained deformation is found to generally cause larger deviatoric stress, less compressive radial and hoop stresses, as well as faster growth of the plastic region, in the matrix. An example case study shows that compared with the undrained case, the drained matrix reaches the same elastoplastic strain with substantially smaller volume of injected fluid inside the embedded inclusion. The solution may be used as a proxy model of caprock integrity problem in CO2 geo-sequestration applications and further as a rigorous benchmark to verify the related numerical solvers. [ABSTRACT FROM AUTHOR]

This paper develops a general and complete solution for the undrained cylindrical cavity expansion problem in nonassociated Mohr‐Coulomb soil under nonhydrostatic initial stress field (i.e., arbitrary K0${{K}_0}$ values of the earth pressure coefficient), by expanding a unique and efficient graphical solution procedure recently proposed by Chen and Wang in 2022 for the special in situ stress case with K0=1${K}_{0}=1$. It is interesting to find that the cavity expansion deviatoric stress path is always composed of a series of piecewise straight lines, for all different case scenarios of K0 being involved. When the cavity is sufficiently expanded, the stress path will eventually end, exclusively, in a major sextant with Lode angle θ in between 5π3$\frac{{5\pi }}{3}$ and 11π6$\frac{{11\pi }}{6}$ or on the specific line of θ=11π6$\theta = \frac{{11\pi }}{6}$. The salient advantage/feature of the present general graphical approach lies in that it can deduce the cavity expansion responses in full closed form, nevertheless being free of the limitation of the intermediacy assumption for the vertical stress and of the difficulty existing in the traditional zoning method that involves cumbersome, sequential determination of distinct Mohr–Coulomb plastic regions. Some typical results for the desired cavity expansion curves and the limit cavity pressure are presented, to investigate the impacts of soil plasticity parameters and the earth pressure coefficient on the cavity responses. The proposed graphical method/solution will be of great value for the interpretation of pressuremeter tests in cohesive‐frictional soils. [ABSTRACT FROM AUTHOR]

At present, sensors and big data create powerful systems capable of real-time monitoring and decision-making. The development of big data in all walks of life is very fast. Big data technology and applications are also gradually accepted by the public, and the data industry is gradually maturing and beginning to enter a rapid development stage. At the same time, the development of the Internet is making data analysis more accurate, and the combination of the two complements each other, contributing to the good development of big data. With the rapid development and wide application of machine learning technology, its application in all walks of life has become increasingly widespread. In this work, we collect the business data of campus restaurants in different time periods to ensure the breadth and depth of the data. The regression algorithm and decision tree algorithm in machine learning are used to integrate and analyze the collected data to reflect the demand tendency of the general public and also the relationship between cost and benefit. We analyze the catering needs of different consumer groups, develop big data applications with greater potential value, and seek long-term development for catering real economy enterprises. [ABSTRACT FROM AUTHOR]

Objective To analyze operative outcomes of endoscopic retrograde cholangiopancreatography (ERCP) rela-ted duodenal perforations. Methods Retrospective analysis was performed with the clinical data of 14 patients who had duodenal perforation during ERCP including 13 cases in Ruijin Hospital and one case in Ruijin Hospital North from Ja-nuary 2011 to May 2014. Surgical timing and procedure were analyzed. Duodenal perforations were classified into types according to Stapfer. Results There were type Ⅰ lesions in 2 cases, type Ⅱ lesions in 10 cases,and type Ⅲ lesions in 2 cases. The time to operation was during ERCP of type Ⅰ injuries, (2.0±1.1) (0-5.0) d of type Ⅱ injuries, and (6.0±2.8) (4.0-8.0) d of type Ⅲ injuries after ERCP with significant statistical difference (P

Stress and deformation analysis of a cavity in an infinite/finite medium is a fundamental applied mechanics problem of interest in multiple physics and engineering disciplines. This paper develops a complete semianalytical solution for the cylindrical cavity expansion in nonassociated Mohr–Coulomb materials, by using the graphical approach and Lagrangian formulation of the cavity boundary value problem (through tracing the responses of a single material point at the cavity wall). The novelty of the new solution framework lies not only in the relaxation of the stringent intermediacy assumption for the vertical stress as usually adopted in the previous analyses, but also in the comprehensive consideration of nonhydrostatic initial stress conditions via arbitrary values of K0 (the coefficient of earth pressure at rest defined as the ratio between the horizontal and vertical initial stresses). The essence of the so-called graphical method, i.e., the unique geometrical analysis and tracking of the deviatoric stress trajectory, is fulfilled by leveraging the deformation requirement that during cavity expansion the progressive development of the radial and tangential strains must maintain to be compressive and tensile, respectively. With the incorporation of the radial equilibrium condition, the problem is formulated to solve a single first-order differential equation for the internal cavity pressure with respect to a pivotal auxiliary variable, for all the distinct scenarios of K0 being covered. Some selected results are presented for the calculated cavity pressure-expansion curve and limit cavity pressure through an example analysis. The definitive semianalytical solution proposed will be not only substantially advancing the current state of knowledge on the fundamental cavity expansion theory, but also able to serve as a unique benchmark for truly verifying the correctness and capability of the classical cornered Mohr–Coulomb constitutive model built in commercial finite element programs. [ABSTRACT FROM AUTHOR]

This paper presents a time-dependent analytical solution for undrained elastoplastic response of a porous, fluid-saturated medium to fluid source at the center of an embedded spherical, porous, fluid-saturated inhomogeneity inclusion. The solution considers poroelastic coupling in the inclusion while solving for the surrounding matrix stress using a Lagrangian formulation of the incurring elastoplastic deformations. The solution for plastic deformation of the matrix is obtained using the large deformation theory of plasticity with associated flow rule of either the strain-hardening Drucker-Prager model or smoothed strain-hardening Mohr-Coulomb model. The obtained solution is used as a proxy model to study caprock stress evolution upon fluid injection in subsurface rocks to mimic applications such as CO2 geo-sequestration. Findings indicate that the (poro)elastic models that are predominantly utilized in the existing studies of the subject could substantially underestimate the caprock shear failure threshold. Results obtained from a presented case study show that 0.8% allowance for elastoplastic strain in the caprock could yield up to 100% increase in fluid injectivity of the embedded reservoir. The presented solution may further serve as a rigorous benchmarking tool for verification of related numerical solution schemes. Caprock integrity concerns arise when injecting fluid into an embedded rock formation, e.g., during CO2 geo-sequestration or when withdrawing fluid from a reservoir, e.g., during oil and gas production. This work assesses possible enhancement in the estimated caprock integrity threshold because of plastic deformation beyond elastic limit, yet prior to rock failure. A time-dependent analytical solution for a geometrically idealized model of porous and fluid-saturated reservoir and surrounding caprock is developed for this purpose. Findings indicate that 0.8% allowance in the caprock total elastoplastic strain beyond elastic limit of the rock results in more than a twofold increase in the injectivity of the embedded reservoir. Higher values of plastic strain-hardening parameter or total strain allowance would allow for higher injectivity thresholds. These results underline the necessity for consideration of plastic deformation and stress analysis in studies on caprock integrity analysis. [ABSTRACT FROM AUTHOR]