Molecular Acceptors Based on a Triarylborane Core Unit for Organic Solar Cells

Triarylboranes that exhibit p–π* conjugation serve as versatile building blocks to design n-type organic/polymer semiconductors. A series of new molecular acceptors based on triarylborane is reported here. These molecules are designed with a boron atom that bears a bulky 2,4,6-tri-tert-butylphenyl (Mes*) substituent at the core and strong electron-withdrawing 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile (IC) units as the end-capping groups that are linked to the core by bithiophene bridges. Butyl or butoxy groups are introduced to the bithiophene units to tune the optoelectronic properties. These molecules show nearly planar backbones with highly localized steric hindrance at the core, low LUMO/HOMO energy levels, and broad absorption bands spanning the visible region, which are all very desirable characteristics for use as electron acceptors in organic solar cell (OSC) applications. The attachment of butyl groups to the bithiophene bridges brings about a slightly twisted backbone, which in turn promotes good solubility and homogeneous donor/acceptor blend morphology, whereas the introduction of butoxy groups leads to improved planarity, favorable stacking in the film state, and a greatly reduced band gap. OSC devices based on these molecules exhibit encouraging photovoltaic performances with power conversion efficiencies reaching up to 4.07 %. These results further substantiate the strong potential of triarylboranes as the core unit of small molecule acceptors for OSC applications.     

Ion pair assisted micro matrix solid phase dispersion extraction of alkaloids from medical plant

A novel micro matrix solid phase dispersion method was successfully used for the extraction of quaternary alkaloids in Phellodendri chinensis cortex. The elution of target compounds was accomplished with sodium hexanesulfonate as the eluent solvent. A neutral ion pair was formed between ion-pairing reagent and positively charged alkaloids in this process, which was beneficial for selectively extraction of polar alkaloids. Several parameters were optimized and the optimal conditions were listed as follows: silica gel as the sorbent, silica to sample mass ratio of 1:1, the grinding time of 1 min. The exhaustive elution of targets was achieved by 200 µL methanol/water (9:1) containing 150 mM sodium hexane sulfonate at pH 4.5. The method validation covered linearity, recovery, precision of intraday and interday, limits of detection, limits of quantitation, and repeatability. This established method was rapid, simple, environmentally friendly, and highly sensitive.     

A coefficient identification problem for a mathematical model related to ductal carcinoma in situ

We consider a coefficient identification problem for a mathematical model with free boundary related to ductal carcinoma in situ (DCIS). This inverse problem aims to determine the nutrient consumption rate from additional measurement data at a boundary point. We first obtain a global‐in‐time uniqueness of our inverse problem. Then based on the optimization method, we present a regularization algorithm to recover the nutrient consumption rate. Finally, our numerical experiment shows the effectiveness of the proposed numerical method.     

Phase transition layers with boundary intersection for an inhomogeneous Allen–Cahn equation

We consider the nonlinear problem of inhomogeneous Allen–Cahn equation

${?}^2\mathrm{\Delta }u+V(y)u(1?u^2)=0\text{in}\mathrm{\Omega },\frac{?u}{?\nu }=0\text{on}?\mathrm{\Omega },$

where Ω is a bounded domain in ${\mathbb{R}}^2$ with smooth boundary, ? is a small positive parameter, ν denotes the unit outward normal of ?Ω, V is a positive smooth function on $\overline{\mathrm{\Omega }}$. Let Γ be a curve intersecting orthogonally with ?Ω at exactly two points and dividing Ω into two parts. Moreover, Γ satisfies stationary and non-degenerate conditions with respect to the functional ${\int }_{\mathrm{\Gamma }}{V}^{1/2}$. We can prove that there exists a solution $u_{?}$ such that: as $?\to 0$, $u_{?}$ approaches +1 in one part of Ω, while tends to ?1 in the other part, except a small neighborhood of Γ.     

Total Synthesis of Lajollamycin B

The first total synthesis of lajollamycin B, a structurally novel nitro-tetraene spiro-β-lactone/γ-lactone antibiotic, is described. The convergent synthesis involves the construction of the C8′–C11′ nitrodienylstannane and its coupling with the segment prepared from the C1′–C7′ ω-iodoheptadienoic acid and the right-hand heterocyclic fragment, which has been utilized for our previous syntheses of oxazolomycin A. The revision of the geometry of the terminal Δ^{10′, 11′}-double bond from E to Z is also described for the structure of natural lajollamycin B.     

In Situ Anchoring of Pyrrhotite on Graphitic Carbon Nitride Nanosheet for Efficient Immobilization of Uranium

Enrichment of U^VI is an urgent project for nuclear energy development. Herein, magnetic graphitic carbon nitride nanosheets were successfully prepared by in situ anchoring of pyrrhotite (Fe₇S₈) on the graphitic carbon nitride nanosheet (CNNS), which were used for capturing U^VI. The structural characterizations of Fe₇S₈/CNNS-1 indicated that the CNNS could prevent the aggregation of Fe₇S₈ and the saturation magnetization was 4.69 emu g⁻¹, which meant that it was easy to separate the adsorbent from the solution. Adsorption experiments were performed to investigate the sorption properties. The results disclosed that the sorption data conformed to the Langmuir isotherm model with the maximum adsorption capacity of 572.78 mg g⁻¹ at 298 K. The results of X-ray photoelectron spectroscopy (XPS) demonstrated that the main adsorption mechanism are as follows: U^VI is adsorbed on the surface of Fe₇S₈/CNNS-1 through surface complexation initially, then it was reduced to insoluble U^IV. Thereby, this work provided an efficient and easy to handle sorbent material for extraction of U^VI.     

Precise Synthesis of Poly(thioester)s with Diverse Structures by Copolymerization of Cyclic Thioanhydrides and Episulfides Mediated by Organic Ammonium Salts

The precise synthesis of poly(thioester)s with diverse structures is still a significant challenge in the polymeric materials field. Herein, we report a novel approach to the synthesis of well‐defined poly(thioester)s by the controlled alternating copolymerization of cyclic thioanhydrides and episulfides induced by simple organic ammonium salts. Both the cation and anion have strong effects on the copolymerization. [PPN]OAc ([PPN]=bis(triphenylphosphine)iminium) with a bulky cation was proven to be efficient in initiating this polymerization, yielding poly(thioester)s with a completely alternating structure, controlled molecular weight, and narrow polydispersity. The poly(thioester) obtained from succinic thioanhydride and propylene sulfide is a typical semicrystalline material, possessing a high refractive index of up to 1.78. Because it uses readily available monomers, this method is expected to open up a new route to poly(thioester)s with diverse structures and properties.     

Ignition delay times of methane and hydrogen highly diluted in carbon dioxide at high pressures up to 300 atm

The need for more efficient power cycles has attracted interest in super-critical CO₂ (sCO₂) cycles. However, the effects of high CO₂ dilution on auto-ignition at extremely high pressures has not been studied in depth. As part of the effort to understand oxy-fuel combustion with massive CO₂ dilution, we have measured shock tube ignition delay times (IDT) for methane/O₂/CO₂ mixtures and hydrogen/O₂/CO₂ mixtures using sidewall pressure and OH* emission near 306?nm. Ignition delay time was measured in two different facilities behind reflected shock waves over a range of temperatures, 1045–1578?K, in different pressures and mixture regimes, i.e., CH₄/O₂/CO₂ mixtures at 27–286 atm and H₂/O₂/CO₂ mixtures at 37–311 atm. The measured data were compared with the predictions of two recent kinetics models. Fair agreement was found between model and experiment over most of the operating conditions studied. For those conditions where kinetic models fail, the current ignition delay time measurements provide useful target data for development and validation of the mechanisms.     

Interior gradient and Hessian estimates for the Dirichlet problem of semi-linear degenerate elliptic systems: A probabilistic approach

In this paper, we give interior gradient and Hessian estimates for systems of semi-linear degenerate elliptic partial differential equations on bounded domains, using both tools of backward stochastic differential equations and quasi-derivatives.     

基于供应方生产能力的应急物资生产模型

利用期权契约所建立的政企合作储备应急物资模式能够有效解决政府单独储备模式所造成的物资储备量过少或过多而引起的困境。然而由于应急物资的需求特性,若应急物资供应企业采用按单生产方式安排生产储备计划,势必会造成库存水平升高,引发资金周转困难等问题,对政企之间的长期合作造成不利影响。基于此,本文设计了基于供应方生产能力的应急物资生产模型。该模型在政府利用批发价格契约与期权契约采购应急物资的基础上,研究了供应方根据自身生产能力进行柔性生产时的生产与储备问题。通过推导政企双方最优决策后,重点分析了期权权利金,执行价格,加急生产成本等参数对供应方生产决策的影响,并证明与按单生产模式相比,柔性生产模式可有效降低供应方的库存量与生产成本,提高其利润,继而提高整体供应链的利润水平,有助于促进政企之间长期稳定的合作。