燃烧福建无烟煤的循环流化床锅炉飞灰及其未燃炭分析

以三个燃烧福建无烟煤的商业CFB锅炉电厂飞灰为研究对象，分析飞灰的粒径和含碳量分布；观察并区分了飞灰中煤炭、烟怠、半焦和灰渣等颗粒的表面形貌；测定了飞灰炭的反应活性并与入炉煤作比较；并研究了飞灰炭的来源。结果表明，采用单级分离装置的CFB锅炉，粒径在0.0385mm～0.0500mm的飞灰质量最多，未燃炭份额也最高；而采用双级分离装置的CFB锅炉，飞灰质量分布和飞灰炭份额的峰值则出现在粒径为0.0500mm~0.0750mm处。飞灰主要由三种形貌的颗粒组成，颗粒状的未燃炭、絮团状的灰渣、和介于两者之间的半焦。与入炉煤相比，飞灰炭的反应活性较高，主要来源于入炉煤中的细粉和燃烧早期因破碎和磨蚀而产生的、来不及在炉膛中燃尽的细小含炭颗粒。入炉煤中易破碎、反应性较高的亮煤是构成电厂CFB锅炉飞灰炭的主要成分。     

Et_2Zn-promoted β-trans-selective hydroboration of ynamide

The trans-hydroboration of alkyne represents a challenging task in organic synthesis.Reported herein is an Et2 Zn promoted β-trans hydroboration of ynamides by using N-heterocyclic carbene(NHC)-ligated borane as boryl source.The reaction leads to a stereoselective construction of enamides bearing a valuable boryl substituent.Both aromatic and aliphatic ynamides were applicable to the reaction.Synthetic transformation of the C-B bond in the product via Suzuki-Miyaura coupling provides a simple and stereospecific route to multi-substituted enamides.Mechanistic studies were conducted and the possible mechanism was discussed     

Laser photolysis of interaction of poly-guanylic acid (5'''') with anthraquinone-2-sulfonate

The electron transfer reaction between triplet anthraquinone-2-sulfonate and poly-guanylic acid (5') in CH3CN-H2O (97 : 3) has been investigated by 248 nm (KrF) laser flash photolysis. The transient absorption spectra and kinetics obtained from the interaction of triplet anthraquinone-2-sulfonate and poly[G] demonstrate that the primary ionic radical pair, radical cation of poly[G] and radical anion of anthraquinone-2-sulfonate have been detected simultaneously. The free energy changes in the process of the electron transfer were also calculated.     

Sensitive fluorimetric method for the determination of aniline by using tetra-substituted amino aluminium phthalocyanine

This is the first report of the determination of aniline with tetra-substituted amino aluminium phthalocyanine (TAAlPc) by a fluorimetric method. In KBr-HCl solution, nitrite ion diazotizes TAAlPc, thus, the fluorescence of TAAlPc is dramatically quenched. However, there is less quenching in the presence of aniline and the recovery in fluorescence intensity is linear with the concentration of aniline. Based on this, a novel method has been developed for the determination of aniline in aqueous solutions. Under the optimal conditions, the calibration graph for aniline is from 5 to 300 ng ml⁻¹ with a 3σ limit of detection of 1.8 ng ml⁻¹. The relative standard deviation for nine replicate measurements of 100 ng ml⁻¹ aniline is 1.7%. The method was applied to the analysis of water samples with satisfactory results.     

Folic acid-based supramolecules for enhanced stability in potassium ion batteries

Organics present significant prospects as environmentally friendly and sustainable electrode materials for potassium ion batteries(PIBs) because of their abundant, recyclable and highly customizable characteristics. However, small molecular organics are easily solubilized in organic electrolytes, resulting in a low capacity and poor stability. Herein, the folic acid-based supermolecules(SM-FAs) are successfully prepared by a hydrothermal assisted self-assembly strategy. Due to multi-locus hydrog...     

Bifurcation and chaos of Tessiet type food chain chemostat with periodically varying substrate

In this paper, we introduce and study a model of Tessiet type food chain chemostat with periodically varying substrate. We investigate the subsystem with substrate and prey and study the stability of the periodic solutions, which are the boundary periodic solutions of the system. The stability analysis of the boundary periodic solution yields an invasion threshold. By use of standard techniques of bifurcation theory, we prove that above this threshold there are periodic oscillations in substrate, prey and predator. Furthermore, we numerically simulate a model with sinusoidal dilution rate, by comparing bifurcation diagrams with different bifurcation parameters, we can see that the periodic system shows two kinds of bifurcations, whose are period-doubling and period-halving.     

A voltammetric sensor for simultaneous determination of lead,cadmium and zinc on an activated carbon fiber rod

A simple, low cost and sensitive voltammetric sensor was developed for the simultaneous detection of Pb²⁺, Cd²⁺, and Zn²⁺ based on a disposable carbon fiber rod (CFR). The important factors to enhance the sensing property were creation of a clean surface by dealing with CFR at a high potential and electrochemical deposition of Bi film to improve the accumulation of heavy metal ions.     

Cyclopiane-type diterpenes from the deep-sea-derived fungus Penicillium commune MCCC 3A00940

Three new cyclopiane diterpenes (1–3) and one rare spirocyclolide (5) were isolated from the deep-sea-derived fungus Penicillium commune MCCC 3A00940, along with 11 known compounds. The planar structures of the new compounds were determined by extensive analysis of their NMR and HRESIMS spectra, and the absolute configurations were established on the basis of specific rotation data in association with calculated ECD spectra. Four of the cyclopiane diterpenes (1–4), with a rigid 6/5/5/5 fused tetracyclic ring framework, are rarely found in Nature. Notably, conidiogenone J (1) is the first naturally occurring enantiomer of the cyclopiane diterpenes. Additionally, penijanthine B (6) and 3-hydroxy-5-methoxystilbene (14) exhibited moderate antiallergic effects with IC₅₀ values of 30 and 33?μM, respectively.     

A note on the critical ideals of a cycle

Critical ideals of a graph G which are the determinantal ideals of its generalized Laplacian matrix were first introduced by Corrales and Valencia as a generalization of the critical group. Then it was shown that critical ideals are also closely related to other properties of the graph, such as the clique number and the zero forcing number. In this note, we give a simple proof of Theorem 4.13 proved in [7], which gives a Gröbner basis of the first nontrivial critical ideal of a cycle. After that as applications we determine explicit expressions for the characteristic ideals of a cycle and the critical groups of a family of thick wheels.     

Global Dynamics of a Diffusive Leslie-Gower Predator-prey Model with Fear Effect

A diffusive Leslie-Gower predator-prey model with fear effect is considered in this paper. For the kinetic system, we show that the unique positive equilibrium is globally asymptotically stable. Moreover, we find that high levels of fear could decrease the population densities of both prey and predator in a long time. For the diffusive model, we obtain the similar results under certain conditions.