ON A SPITZER-TYPE LAW OF LARGE NUMBERS FOR PARTIAL SUMS OF INDEPENDENT AND IDENTICALLY DISTRIBUTED RANDOM VARIABLES UNDER SUB-LINEAR EXPECTATIONS

Miaomiao Wang,Min Wang,Xuejun Wang Korean Mathematical Society 2023 대한수학회보 Vol.60 No.3

In this paper, under some suitable conditions, we study the Spitzer-type law of large numbers for the maximum of partial sums of independent and identically distributed random variables in upper expectation space. Some general results on necessary and sufficient conditions of the Spitzer-type law of large numbers for the maximum of partial sums of independent and identically distributed random variables under sublinear expectations are established, which extend the corresponding ones in classic probability space to the case of sub-linear expectation space.

A surfactant-free microemulsion containing diethyl malonate, ethanol, and water: Microstructure, micropolarity and solubilizations

Miaomiao Song,Wenjiao Liu,Qian Wang,Jiao Wang,Jinling Chai 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.83 No.-

The microstructure, micropolarity and solubilizations of a surfactant-free microemulsion (SFME)containing diethyl malonate (DEM), ethanol (EtOH), and water were investigated in details. The ternaryphase diagram of the SFME was constructed, and the single-phase region of the diagram was divided intooil in water (O/W), bicontinuous (B.C.), and water in oil (W/O) subregions. The dynamic light scattering(DLS) results showed that there is an orderly microstructure in each subregion of the system. The UV–visabsorbance spectra of CoCl2 indicated the formation of complete W/O SFME droplets, when the watercontent is relatively large. With an increase in water content, the association between Cu2+ and watermolecules increases, resulting in a red shift of the UV–vis absorbance spectra of CuCl2. The solubilizationof K3Fe(CN)6 in the W/O SFME was investigated, and found that the SFME has better solubilization effecton inorganic salts. Riboflavin also has a strong solubilizing effect in the W/O SFME, and the absorbanceconforms to Lambert–Beer’s law. When the water content is small, the absorbance deviates fromLambert–Beer’s law. This is in agreement with the results of the solubilization of CoCl2. A complete W/OSFME could be formed when the water mass fraction (W) exceeds 0.10.

Improved oral bioavailability of capsaicin via liposomal nanoformulation: preparation, in vitro drug release and pharmacokinetics in rats

Yuan Zhu,Miaomiao Wang,Jiajia Zhang,Wei Peng,Caleb Kesse Firempong,Wenwen Deng,Qilong Wang,Shicheng Wang,Feng Shi,Jiangnan Yu,Ximing Xu,Weiming Zhang 대한약학회 2015 Archives of Pharmacal Research Vol.38 No.4

This study innovatively prepared an effectivecapsaicin-loaded liposome, a nanoformulation with fewerirritants, for oral administration. The in vitro and in vivoproperties of the liposomal encapsulation were investigatedand the potential possibility of oral administration evaluated. The liposomal agent composed of phospholipid, cholesterol,sodium cholate and isopropyl myristate was prepared usingfilm-dispersion method. A level A in vitro–in vivo correlation(IVIVC) was established for the first time, which demonstratedan excellent IVIVC of both formulated and freecapsaicin in oral administration. Physicochemical characterizationsincluding mean particle size, zeta (f) potentialand average encapsulation efficiency of capsaicin-loadedliposome were found to be 52.2 ± 1.3 nm, -41.5 ±2.71 mv and 81.9 ± 2.43 %, respectively. In vivo, liposomalencapsulation allowed a 3.34-fold increase in relativebioavailability compared to free capsaicin. The gastricmucosa irritation studies indicated that the liposomal systemwas a safe carrier for oral administration. These resultssupport the fact that capsaicin, an effective drug for thetreatment of neuropathic pain, could be encapsulated inliposome for improved oral bioavailability. The excellentIVIVC of capsaicin-loaded liposome could also be a promisingtool in liposomal formulation development with anadded advantage of reduced animal testing.

Siderophore Production by Rhizosphere Biological Control Bacteria Brevibacillus brevis GZDF3 of Pinellia ternata and Its Antifungal Effects on Candida albicans

Miaomiao Sheng,Huake Jia,Gongyou Zhang,Lina Zeng,Tingting Zhang,Yaohang Long,Jing Lan,Zuquan Hu,Zhu Zeng,Bing Wang,Hongmei Liu 한국미생물·생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.5

Brevibacillus brevis GZDF3 is a gram-positive, plant growth-promoting rhizosphere bacterium (PGPR) isolated from the rhizosphere soil of Pinellia ternata (an important herb in traditional Chinese medicine). The GZDF3 strain produces certain active compounds, such as siderophores, which are the final metabolite products of non-ribosomal peptide synthetase (NRPS) and independent non-ribosomal peptide synthetase (NIS) activity. With the present study, we attempted to investigate the siderophore production characteristics and conditions of Bacillus sp. GZDF3. The antibacterial activity of the siderophores on pathogenic fungi was also investigated. Optimal conditions for the synthesis of siderophores were determined by single factor method, using sucrose 15 g/l, asparagine 2 g/l, 32°C, and 48 h. The optimized sucrose asparagine medium significantly increased the production of siderophores, from 27.09% to 54.99%. Moreover, the effects of different kinds of metal ions on siderophore production were explored here. We found that Fe3+ and Cu2+ significantly inhibited the synthesis of siderophores. The preliminary separation and purification of siderophores by immobilized-metal affinity chromatography (IMAC) provides strong antibacterial activity against Candida albicans. The synergistic effect of siderophores and amphotericin B was also demonstrated. Our results have shown that the GZDF3 strain could produce a large amount of siderophores with strong antagonistic activity, which is helpful in the development of new biological control agents.

Rational design of porous NiCo2S4 nanotubes for hybrid supercapacitor

Wang Haiyang,Liang Miaomiao,He Zemin,Guo Zhun,Zhao Yang,Li Kexuan,Song Wenqi,Zhang Yongming,Zhang Xin,Zhao Yuzhen,Miao Zongcheng 한국물리학회 2022 Current Applied Physics Vol.35 No.-

The nanotube-consisted flower-like NiCo2S4 is successfully fabricated by a novel two-step hydrothermal technique. X-ray diffraction (XRD) identifies the spinel structure, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) imply the flower-like morphology of the synthesized NiCo2S4. The electrochemical behaviors are studied by cyclic voltammetry and galvanostatic charge-discharge measurements. The NiCo2S4 nanotubes demonstrate enhanced pseudocapacitive performance of 429.5 C g− 1 at current density of 0.5 A g− 1 . The NiCo2S4//AC device delivers high energy density of 37.69 Wh kg− 1 , maximum power density of 4000.6 W kg− 1 and satisfied cycle property of 96% capacitance retention after over 7000 cycles. The results show that the NiCo2S4 nanotubes are promising electrode material for high performance supercapacitor applications.

Terminal sliding mode control for full vehicle active suspension systems

Miaomiao Du,Dingxuan Zhao,Bin Yang,Lili Wang 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.6

In current study, a terminal sliding mode control approach different from the conventional sliding mode control is proposed for active suspension system, which has an ability to reach the sliding surface in a finite time to achieve a high control accuracy. A full vehicle active suspension model is adopted with consideration of system uncertainties. The terminal sliding mode controller (TSMC) is systematically designed to force motion trajectories of vehicle body to accurately track the ideal reference model, and the controller parameters are tuned by a novel kidney-inspired algorithm (KA) for better control performance. The thought of designing an adaptive scheme for the reference model is one of the main contribution of this work. Simulation results clearly show the strength of adaptive scheme. The effectiveness and the strong robustness in stabilizing the attitude of the vehicle and improving the ride comfort are the main positive features of the proposed TSMC.

Study on rock fracture behavior under hydromechanical loading by 3-D digital reconstruction

Miaomiao Kou,Xinrong Liu,Yunteng Wang 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.74 No.2

The coupled hydro-mechanical loading conditions commonly occur in the geothermal and petroleum engineering projects, which is significantly important influence on the stability of rock masses. In this article, the influence of flaw inclination angle of fracture behaviors in rock-like materials subjected to both mechanical loads and internal hydraulic pressures is experimentally studied using the 3-D X-ray computed tomography combined with 3-D reconstruction techniques. Triaxial compression experiments under confining pressure of 8.0 MPa are first conducted for intact rock-like specimens using a rock mechanics testing system. Four pre-flawed rock-like specimens containing a single open flaw with different inclination angle under the coupled hydro-mechanical loading conditions are carried out. Then, the broken pre-flawed rock-like specimens are analyzed using a 3-D X-ray computed tomography (CT) scanning system. Subsequently, the internal damage behaviors of failed pre-flawed rock-like specimens are evaluated by the 3-D reconstruction techniques, according to the horizontal and vertical cross-sectional CT images. The present experimental does not only focus on the mechanical responses, but also pays attentions to the internal fracture characteristics of rock-like materials under the coupled hydro-mechanical loading conditions. The conclusion remarks are significant for predicting the rock instability in geothermal and unconventional petroleum engineering.

Dynamic fracture instability in brittle materials: Insights from DEM simulations

Miaomiao Kou,Dongchen Han,Congcong Xiao,Yunteng Wang 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.71 No.1

In this article, the dynamic fracture instability characteristics, including dynamic crack propagation and crack branching, in PMMA brittle solids under dynamic loading are investigated using the discrete element method (DEM) simulations. The microscopic parameters in DEM are first calibrated using the comparison with the previous experimental results not only in the field of qualitative analysis, but also in the field of quantitative analysis. The calibrating process illustrates that the selected microscopic parameters in DEM are suitable to effectively and accurately simulate dynamic fracture process in PMMA brittle solids subjected to dynamic loads. The typical dynamic fracture behaviors of solids under dynamic loading are then reproduced by DEM. Compared with the previous experimental and numerical results, the present numerical results are in good agreement with the existing ones not only in the field of qualitative analysis, but also in the field of quantitative analysis. Furthermore, effects of dynamic loading magnitude, offset distance of the initial crack and initial crack length on dynamic fracture behaviors are numerically discussed.

Peridynamic analysis of dynamic fracture behaviors in FGMs with different gradient directions

Miaomiao Kou,Jing Bi,Binhang Yuan,Yunteng Wang 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.75 No.3

In this article, a developed bond-based peridynamic model for functionally graded materials (FGMs) is proposed to simulate the dynamic fracture behaviors in FGMs. In the developed bond-based peridynamic model for FGMs, bonds are categorized into three different types, including transverse directionally peridynamic bond, gradient directionally peridynamic bond and arbitrary directionally peridynamic bond, according to the geometrical relationship between directions of peridynamic bonds and gradient bonds in FGMs. The peridynamic micromodulus in the gradient directionally and arbitrary directionally peridynamic bonds can be determined using the weighted projection method. Firstly, the standard bond-based peridynamic simulations of crack propagation and branching in the homogeneous PMMA plate are performed for validations, and the results are in good agreement with the previous experimental observations and the previous phase-field numerical results. Then, the numerical study of crack initiation, propagation and branching in FGMs are conducted using the developed bond-based peridynamic model, and the influence of gradient direction on the dynamic fracture behaviors, such as crack patterns and crack tip propagation speed, in FGMs is systematically studied. Finally, numerical results reveal that crack branching in FGMs under dynamic loading conditions is easier to occur as the gradient angle decreases, which is measured by the gradient direction and direction of the initial crack.

SOOT DEVELOPMENT IN AN OPTICAL DIRECT INJECTION SPARK IGNITION ENGINE FUELED WITH ISOOCTANE

Fangxi Xie,Miaomiao Zhang,Yongzhen Wang,Yan Su,Wei Hong,Peng Cheng 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.2

To better understand the formation and evolution processes of soot, the two-color laser induced incandescence diagnostic method was applied on a single cylinder optical direct injection spark ignition engine. Soot volume fraction was measured, and soot distribution was imaged as cyclic fuel quantity changes. The results show that 45.5 mg/cycle generates the most soot at the same measure plane. Pool fire dominates the formation of soot in the tested engine and generates more soot on the top surface of the piston near the injector. In-cylinder soot increases until 42°CA ATDC and then reduces due to oxidation. Pool fire continues through the expansion stroke till 52°CA ATDC, and then soot cloud gathers near the 10 mm plane. After 82°CA ATDC, in-cylinder soot basically in equilibrium, and residual soot moves follow the in-cylinder flow randomly and evenly distributes within the whole combustion chamber. With increasing cyclic fuel quantity, particles number concentration gradually increases and their distribution present dual-peak shape. In detail, 45.5 mg/cycle emits the most accumulation mode particles while 52 mg/cycle emits the most nucleation mode particles.