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On asymptotic of extremes from generalized Maxwell distribution
Jianwen Huang,Jianjun Wang 대한수학회 2018 대한수학회보 Vol.55 No.3
In this paper, with optimal normalized constants, the asymptotic expansions of the distribution and density of the normalized maxima from generalized Maxwell distribution are derived. For the distributional expansion, it shows that the convergence rate of the normalized maxima to the Gumbel extreme value distribution is proportional to $1/\log n.$ For the density expansion, on the one hand, the main result is applied to establish the convergence rate of the density of extreme to its limit. On the other hand, the main result is applied to obtain the asymptotic expansion of the moment of maximum.
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Effects of TETA or TEPA Loading on CO2 Adsorption Properties Using Pore-Expanded KIT-6 as Support
Jianwen Wei,Dejun Mei,Zhifeng Lin,Linlin Geng,Siqi Chen,Lei Liao 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.4
Mesoporous silica pore-expanded KIT-6 was synthesized using tetraethoxysilane (TEOS) as the silica source, tri-block copolymer (P123) as a structure-directing agent and 1,3,5-trimethylbenzene (TMB) as swelling agents by a hydrothermal method. Then, pore-expanded KIT-6 (PE-KIT-6) was modified with different amounts of amines including triethylenetetramine (TETA) and tetraethylenepentamine (TEPA) by a post-synthetic impregnation method. The samples were characterized by small-angle X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2 adsorption/desorption, elemental analysis and thermal gravimetric analysis (TGA). Experimental results revealed that the modifiers were introduced into the samples and the CO2 adsorption capacity increased first and then decreased with the increase of TETA/TEPA loadings. Under the same loadings of TETA/TEPA, the samples modified by TEPA exhibited better CO2 adsorption capacities than the samples modified by TETA because TEPA has one more amine group than TETA in the molecule. The results also indicated that the samples had good adsorption capacities at the loadings ranging from 30% to 35%. Among them, the sample modified by TEPA with the loading of 35% had the maximum adsorption capacity of 2.9mmol/g. After five cycles of adsorption/desorption, the adsorption capacity only dropped 4.59%, indicating that the adsorbent of PE-KIT-6 modified by TEPA has good cyclic stability.
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Jianwen Li,He Lian 대한약학회 2016 Archives of Pharmacal Research Vol.39 No.6
As a complex endocrine and metabolic disorder,type 2 diabetes mellitus (non-insulin-dependent diabetesmellitus, NIDDM) has become a major threat to humanhealth. Because of the heterogeneous and progressive disordersinduced by insulin resistance and pancreatic b-celldysfunction, the treatment of NIDDM is still challenging. Although antidiabetic drugs with different pharmacologicalmechanisms of action have been used clinically, differentdegrees of undesirable glucose control and the incidencesof a variety of side effects, including hypoglycemia, cardiovascularcomplications and weight gain require thebetter treatment options. This article has overviewed thecurrent literature about commercially available antidiabeticdrugs with different pharmacological mechanisms of actionin the treatment of NIDDM, and summarized the publisheddata regarding the efficacy, tolerability, and safety of currentlyavailable single preparations and fixed-dose combinations,aiming to provide important information for thedevelopment and application of antidiabetic drugs in thefuture. The literature search from 1989 to 2015 wasconducted by PubMed, ScienceDirect, Springer, AmericanDiabetes Association, and U.S. FDA Drugs databases.
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Jianwen Bai,Yanru Zhao,Jinna Shi,Xiaoyan He 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.11
Many researchers have been searching for the alternative for natural river sand as fine aggregate for concrete preparation. Thus, whether it is feasible to replace natural river sand by aeolian sand in concrete partially or totally is studied. At the macroscale, a universal testing machine and concrete rapid freeze–thaw equipment are applied in testing mechanical properties as well as frost resistance durability, respectively. At the mesoscale, a scanning electron microscope has been taken for observing and analyzing the interfacial transition zone in aeolian sand concrete. At the microscale, nuclear magnetic resonance is used for testing pore structure evolution. Simultaneously, the macro- and microrelationships between compressivestrength and total and interval porosities are established. The grey correlation model is adopted to analyze the main microscopic pore parameters that affect aeolian sand concrete’s frost resistance durability. Results show that the workability and mechanical properties of aeolian sand concrete first increase and subsequently reduce as aeolian sand content increases, and the optimum content is 30%. The influence mechanism is that aeolian sand particles with different contents change the linear packing density of fine aggregate and affect the aggregate gradation and pore structure. The compressive strength has a negative linear relation to total porosity and porosity of more harmful pores (>200 nm) and an insignificant correlation with the porosity of non-more harmful pores (<200 nm). A medium and low content of aeolian sand (10% – 60%) partly improves concrete frost resistance, whereas a large content (80% – 100%) significantly improves concrete frost resistance. Grey correlation analysis shows the most important microstructural factor influencing the macroscopic frost resistance durability in aeolian sand concrete should be the relative proportion of more harmful and harmless pores. The findings of this research expand aeolian sand concrete’s application in cold areas and provide a new way for the reuse of waste resources.
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Jianwen Chen,Han Zhou,Bing Zhao,Wujun Chen,Mingyang Wang,Zhihong Xu 한국섬유공학회 2018 Fibers and polymers Vol.19 No.12
Tensile tests of seven bias angles with a 15 o increment with respect to the warp direction are conducted on a typical coated bi-axial warp knitted fabric (BWKF). By utilizing the Digital Image Correlation technique, the experimental results are processed, and detailed responses of strain contours and Poisson’s ratios are determined for some specific strain levels, and an extraordinary M-shaped relationship between Poisson’s ratio and bias angle is revealed. Then, the tested Poisson’s ratios are compared with corresponding theoretical predictions from the original theory for ordinary anisotropic materials, discrepancies and their possible causes are analyzed. Finally, the original theory used for Poisson’s ratio predication of ordinary anisotropic materials is modified for application to the BWKFs by considering the unique local valley at 45 o caused by structural differences and possible yarn movements. The modified theoretical equation could exhibit the Mshaped relationship between Poisson’s ratio and bias angle, and is validated due to the high similarity between the predictions and experimental results. This investigation could provide some new insights into the orientation-dependence, Poisson’s effect and complex deformation mechanism of BWKFs.
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Formulation of nimodipine nanocrystals for oral administration
Jianwen Li,Qiang Fu,Xiaohong Liu,Mo Li,Yongjun Wang 대한약학회 2016 Archives of Pharmacal Research Vol.39 No.2
The aim of this paper is to optimize nimodipine (NMD) nanocrystals (NCs) for oral administration. The effects of independent process variables (microprecipitation temperature, shearing speed, shearing time, homogenization pressure and number of cycles) on the particle size have been studied. Experiments were conducted to optimize the formulation composition. A single factor exploration was used to screen the primary stabilizers. Then, the selected polymers/surfactants were further optimized using an L9 (34) orthogonal design. The optimal formulation was composed of NMD (0.7 %, w/v), F127 (0.4 %, w/v), HPMC-E5 (0.1 %, w/v), and sodium deoxycholate (0.05 %, w/v) and was rod-shaped as shown by SEM observations, and it had a particle size of 833.3 ± 20.6 nm, determined by laser diffraction. These aqueous NCs were physically stable for 15 days. To further improve the stability, the NCs were freeze-dried. The powder obtained exhibited acceptable flowability and was physically stable for at least 24 months. Additionally, the NMD NCs displayed much higher dissolution profiles than the bulk drug. The pharmacokinetic results showed that the relative bioavailability was 397 % in comparison with Nimotop, suggesting that NCs are an efficient strategy for improving the oral bioavailability of poorly water-soluble drugs.
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