Let $ \alpha\in (1, 2], \beta\in (0, 1) $ with $ \alpha-\beta > 1 $. This paper focused on the multiplicity of positive solutions for a singular tempered fractional boundary value problem \begin{document}$ \begin{equation*} \left\{\begin{aligned}\ & -{^R _0}{{\mathbb{D}_t}^{\alpha,\lambda}} u(t) = p(t)h\left(e^{\lambda t} u(t), {^R _0}{{\mathbb{D}_t}^ {\beta,\lambda}}u(t)\right), t\in(0,1),\\& {^R _0}{{\mathbb{D}_t}^ {\beta,\lambda}}u(0) = 0, \ \ {^R _0}{{\mathbb{D}_t}^ {\beta,\lambda}}u(1) = 0, \end{aligned}\right. \end{equation*} $\end{document} where $ h\in C([0, +\infty)\times[0, +\infty), [0, +\infty)) $ and $ p \in L^1([0, 1], (0, +\infty)) $. By applying reducing order technique and fixed point theorem, some new results of existence of the multiple positive solutions for the above equation were established. The interesting points were that the nonlinearity contained the lower order tempered fractional derivative and that the weight function can have infinite many singular points in $ [0, 1] $.

We study the following Schrödinger-Poisson-Slater type system: \begin{equation}\label{eq:0.1} \begin{cases} -\Delta u + V(x) u + \lambda\phi (x) u =|u|^{p-1}u,& x\in \mathbb{R}^3, \\ -\Delta\phi = u^2, \quad \lim\limits_{|x|\to +\infty}\phi (x)=0, \end{cases} \end{equation} where $\lambda> 0$ is a parameter, $p\in (1,2)$, $V\in C(\mathbb{R}^N,\mathbb{R}_0^+)$. If $V$ is a constant, or $p \in (2,5)$ with $V\in L^{\infty}(\mathbb{R}^3)$, the above system has been considered in many papers. In this paper, we are interested in the case: $p\in (1,2)$ and $V$ being a coercive potential, i.e., $\lim\limits_{|x|\to +\infty} V(x)=\infty$. We prove that there exists $\lambda_0> 0$ such that system (\ref{eq:0.1}) has at least two positive solutions $u^0_\lambda$ and $u^1_\lambda$ for any $\lambda \in (0, \lambda_0)$. Moreover, $u^0_\lambda$ is a ground state (i.e., the least energy solution) which must blow up as $\lambda \rightarrow 0$. Particularly, when $p\in ({11}/{7},2)$ and $\lambda> 0$ is small enough, we show that the ground state of (\ref{eq:0.1}) must be non-radially symmetric even if $V(x)=V(|x|)$, such as $V(x)=|x|^2$.

In this paper, we focus on the existence and asymptotic estimates of the maximal and minimal solutions for a coupled tempered fractional differential system with different orders. By introducing an order reduction technique and some new growth conditions, we establish some new results on the existence of positive extremal solutions for the tempered fractional differential system, meanwhile, we also obtain the asymptotic estimate of the positive extreme solution by an iterative technique, which possesses a sharp asymptotic estimate. In particular, the iterative sequences converging to maximal and minimal solutions starting from two known initial values are easy to compute. Moreover, the weight function ${\hslash }_i$ is allowed to have an infinite number of singular points in $[0,1]$.