Activation of aliphatic carbon-carbon bonds of esters and amides by rhodium(II) porphyrin

Aliphatic carbon-carbon bonds of esters and amides were activated successfully with rhodium(II) porphyrin radical to give rhodium(III) porphyrin alkyls in moderate yields.     

A Network-Pharmacology-Combined Integrated Pharmacokinetic Strategy to Investigate the Mechanism of Potential Liver Injury due to Polygonum multiflorum

Polygonum multiflorum (PM) has been used as a tonic and anti-aging remedy for centuries in Asian countries. However, its application in the clinic has been hindered by its potential to cause liver injury and the lack of investigations into this mechanism. Here, we established a strategy using a network pharmacological technique combined with integrated pharmacokinetics to provide an applicable approach for addressing this issue. A fast and sensitive HPLC-QQQ-MS method was developed for the simultaneous quantification of five effective compounds (trans-2,3,5,4′-tetrahydroxystilbene-2-O-β-d-glucoside, emodin-8-O-β-d-glucoside, physcion-8-O-β-d-glucoside, aloe-emodin and emodin). The method was fully validated in terms of specificity, linearity, accuracy, precision, extraction recovery, matrix effects, and stability. The lower limits of quantification were 0.125–0.500 ng/mL. This well-validated method was successfully applied to an integrated pharmacokinetic study of PM extract in rats. The network pharmacological technique was used to evaluate the potential liver injury due to the five absorbed components. Through pathway enrichment analysis, it was found that potential liver injury is primarily associated with PI3K-Akt, MAPK, Rap1, and Ras signaling pathways. In brief, the combined strategy might be valuable in revealing the mechanism of potential liver injury due to PM.     

On the Derivative Counting Processes of First- and Second-order Aggregated Semi-Markov Systems

Methodology and Computing in Applied Probability - In this paper, first- and second-order discrete-time semi-Markov systems are considered with their finite state space divided into three subsets...     

Moments for Hawkes Processes with Gamma Decay Kernel Functions

Methodology and Computing in Applied Probability - Hawkes processes have been widely studied, but their many probability properties are still difficult to obtain, including their moments. In the...     

Optimization of Extraction Conditions of Carotenoids from Dunaliella parva by Response Surface Methodology

Extraction conditions can exert a remarkable influence on extraction efficiency. The aim of this study was to improve the extraction efficiency of carotenoids from Dunaliella parva (D. parva). Dimethyl sulfoxide (DMSO) and 95% ethanol were used as the extraction solvents. The extraction time, extraction temperature and the proportions of mixed solvent were taken as influencing factors, and the experimental scheme was determined by Central Composite Design (CCD) of Design Expert 10.0.4.0 to optimize the extraction process of carotenoids from D. parva. The absorbance values of the extract at 665 nm, 649 nm and 480 nm were determined by a microplate spectrophotometer, and the extraction efficiency of carotenoids was calculated. Analyses of the model fitting degree, variance and interaction term 3D surface were performed by response surface analysis. The optimal extraction conditions were as follows: extraction time of 20 min, extraction temperature of 40 °C, and a mixed solvent ratio (DMSO: 95% ethanol) of 3.64:1. Under the optimal conditions, the actual extraction efficiency of carotenoids was 0.0464%, which was increased by 18.19% (the initial extraction efficiency of 0.03926%) with a lower extraction temperature (i.e., lower energy consumption) compared to the standard protocol.     

Application of tubular tetrapod magnesium oxide in a biosensor for hydrogen peroxide

Tubular tetrapod magnesium oxide (tt-MgO) can be synthesized by thermal evaporation of Mg metal powder with a pre-grown tetrapod ZnO template. The morphology and structure of the tt-MgO were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. A composite prepared from tt-MgO, nafion and horseradish peroxidase was employed to modify a gold electrode to result in an electrochemical biosensor for hydrogen peroxide that displays excellent sensitivity and rapid response in the presence of hydroquinone as a mediator. Its sensitivity is 335.4 μA mM^-1 cm^-2, its response is linear in the range from 1.0 to 450 μM, and the detection limit is 0.3 μM. These results demonstrate that tt-MgO provides a promising material for the designs of biosensors.

一类独立的动态投入产出模型

Sargan．J．D从数学上指出[11]Leontief模型的内在不稳定性,由此引发数学上的争论,并使数学在该领域的应用研究取得重大结果,近年来,许多学者使用规划等方法避开此模型的不稳定性,找出了此模型的稳定增长解．对应于不同的经济体制,动态投入产出模型也表现出其形式的多样性．对时滞为1的前向延迟型动态投入产出模型,我们已经得出其稳定增长解。最近,曾立生提出了取消A为不可约的条件后,非负矩阵正向量唯一存在的条件．现实中,由下度量误差、经济技术的变化、管理技术的变化等众多原因,使投入产出消耗系数矩阵及投资系数矩阵在实现时是随机波动的,因此,有必要研究随机动态投入产出模型．另一方面,由于研究方式的不同,概率分析的方法会在动态投入产出模型的研究中得到意想不到的效果．     

Development of a gold nanoparticles based chemiluminescence imaging assay and its application

In this paper, a novel gold nanoparticles based protein immobilization method was designed. Biocomposites of gold nanoparticles and proteins were successfully coated on poly(methyl methacrylate) (PMMA) plates and polystyrene microtiter plates. The proteins could be immobilized on solid materials with high density and better bioactivity. Based on above design, chemiluminescence (CL) imaging assay for determination of H₂O₂ and recombinant human interleukin-6 (rHu IL-6) was developed. The linear range and the loading capability were greatly improved when compared with imaging assay performed with direct proteins immobilization. Under the selected experimental conditions, a linear relationship was obtained between the CL intensity and the concentration of H₂O₂ in the range of 1.0 × 10⁻⁶ to 1.0 × 10⁻⁴ mol L⁻¹, and rHu IL-6 in the range of 2.0-312.0 pg mL⁻¹. The detection limits were 2 × 10⁻⁷ mol L⁻¹ (3σ) for H₂O₂ and 0.5 pg mL⁻¹ for rHu IL-6 with relative standard deviation of 3.8% for 3.0 × 10⁻⁵ mol L⁻¹ H₂O₂, and 4.4% for 39.0 pg mL⁻¹ rHu IL-6. This method has been applied to the determination of rHu IL-6 in human serum with satisfactory results.