17,706 research outputs found
Investigating Crystallization Tendency, Miscibility and Molecular interactions of drug-polymer systems for the development of amorphous solid dispersions
No full textThis project aims to characterize the crystallization tendencies, miscibility and molecular interaction in drug-polymer systems of poorly soluble drugs and correlate it with the performance of prepared or reported SDs (solid dispersions). Crystallization tendencies of five different drugs [i.e. Curcumin (CUR), indomethacin (IND), flutaminde (FLU), dipyridamole (DIP), griseofulvin (GRI)] in absence and presence of four different polymers [i.e. polyethylene glycol (PEG), eudragit EPO (EPO), hydroxypropyl methylcellulose (HPMC) and polyvinyl pyrrolidone (PVP)] in various drug-polymer ratios were determined by using modulated differential scanning calorimetry (MDSC). Thermal analysis i.e. glass transition temperature (Tg), crystallinity and melting point depression along with theoretical calculations such as solubility parameter were performed to study drug polymer miscibility. Molecular interactions were predicted by using Tg deviations and molecular modeling. Physical states of drug in the SDs were characterized by X-ray diffraction (XRD) and MDSC. IR (Infrared) and Raman were used in selected systems (i.e. CUR, DIP and GRI systems) to explore the role of drug polymer interactions in amorphization of SDs. Dissolution studies using USP apparatus II and physical stability study at room temperature were performed for selected systems. Based on the absence and presence of endothermic and exothermic peaks (heat-cool-heat cycle) in MDSC, the crystallization tendency of pure drugs was categorized as low, moderate and high. In presence of selected polymers, crystallization tendency of all the drugs can be modified albeit high polymer concentration was required for drugs with high crystallization tendency i.e. DIP and GRI (> 50%w/w). Polymers showing greater effect on crystallization tendency of drugs were found to have higher drug-polymer miscibility and stronger molecular interactions. For example, FLU- PVP system showed good miscibility and no remarkable Tg deviation. This is reflected in its ability to change the crystallization tendency of FLU. Further, the results correlated well with the physical state, dissolution and stability of prepared/reported SDs. The developed approach has significant potential to be a rational screening method for the development of amorphous SDs.ProQuest Traditional Publishing Optionxxiii, 130 page
White Jade Figure of Wu Meng
No full textSmall pale celadon/white jade carving of Wu Meng, one of the Twenty-Four Paragons of Filial Piety, holding his feather fan. Wu Meng was a disciple of the magician Ting I. The milky white jade has areas rust colored areasQianlong reignQing Dynast
White Jade Figure of Wu Meng
No full textSmall white jade carving of Wu Meng, one of the Twenty-Four Paragons of Filial Piety, crossing a turbulent river waving his feather fan, as winds hindered his progress. Wu Meng was a disciple of the magician Ting I. The milky white jade has areas of a reddish brown.Kangxi reignQing Dynast
Hesei toktobuha Sirame acabuha tulergi monggo hoise aiman-i wang gung sai iletun. [Qin ding Xu zuan wai fan meng-gu hui bu wang gong biao 欽定續纂外藩蒙古回部王公表.]
No full textHesei toktobuha Sirame acabuha tulergi monggo hoise aiman-i wang gung sai iletunQin ding Xu zuan Wai fan meng-gu hui bu wang gong biaoSirame acabuha tulergi monggo hoise aiman-i wang gung sai iletunHesei toktobuha Sirame acabuha tulergi monggo hoise aiman-i wang gung sai iletunXu zuan wai fan meng gu hui bu wang gong biaoQin ding Xu zuan wai fan meng gu hui bu wang gong biaoNumérisation effectuée à partir d'un document de substitution.Incomplet. Subsistent les fascicules 3-9 et 12 (juan 3-9 et 12). Texte mandchou. Tables.Provient de la mission P. Pelliot
An Optimal Real-time Pricing Algorithm for the Smart Grid: A Bi-level Programming Approach
No full textThis paper proposes an improved approach to our previous work [meng2012stackelberg]. [meng2012stackelberg] uses Stackelberg game to model the interactions between electricity retailer and its customers and genetic algorithms are used to obtain the Stackelberg Equilibrium (SE). In this paper, we propose a bi-level programming model by considering benefits of the electricity retailer (utility company) and its customer. In the upper level model, the electricity retailer determines the real-time retail prices with the aim to maximize its profit. The customer reacts to the prices announced by the retailer aiming to minimize their electricity bills in the lower level model. In order to make it more tractable, we convert the hierarchical bi-level programming problem into one single level problem by replacing the lower lever's problem with his Karush–Kuhn–Tucker (KKT) conditions. A branch and bound algorithm is chosen to solve the resulting single level problem. Experimental results show that both the bi-level programming model and the solution method are feasible. Compared with the genetic algorithm approach proposed in work [meng2012stackelberg], the branch and bound algorithm in this paper is more efficient in finding the optimal solution
Migrant workers, collaborative research and spatial pressures : an interview with Meng Yue
No full textIn July last year I had the opportunity to interview Meng Yue, literary scholar and author of Shanghai and the Edges of Empire (2006). Meng Yue has been collaborating with Toronto-based architect and artist Adrian Blackwell for a number of years, with their students from literature and architecture undertaking highly interesting research on the peripheral zones of Beijing. Questions of peri-urban food production, land use, resource distribution and the multiplication of labour skills have framed these investigations. The interview below is extracted from a considerably longer discussion we had in Beijing during the late summer of 2007, half of which was lost to the faulty battery of an ipod (the rest remains to be transcribed from video…)
Qualitative and Quantitative Methods to Determine Miscibility in Amorphous Drug-Polymer Systems
No full textAmorphous drug–polymer systems or amorphous solid dispersions are commonly used in pharmaceutical industry to enhance the solubility of compounds with poor aqueous solubility. The degree of miscibility between drug and polymer is important both for solubility enhancement as well as for the formation of a physically stable amorphous system. Calculation of solubility parameters, Computational data mining, Tg measurements by DSC and Raman mapping are established traditional methods used to qualitatively detect the drug–polymer miscibility. Calculation of Flory–Huggins interaction parameter, computational analysis of X-Ray Diffraction (XRD) data, solid state Nuclear Magnetic Resonance (NMR) spectroscopy and Atomic Forced Microscopy (AFM) have been recently developed to quantitatively determine the miscibility in amorphous drug–polymer systems. This brief review introduces and compiles these qualitative and quantitative methods employed in the evaluation of drug–polymer miscibility. Combination of these techniques can provide deeper insights into the true miscibility of the drug–polymer systems
Correction to: Visible lattice points along curves
No full textThe article “Visible lattice points along curves”, written by Kui Liu and Xianchang Meng, was originally published electronically on the publisher’s internet portal on 27 July 2020 without open access. With the author(s)’ decision to opt for Open Choice the copyright of the article changed on 9 July 2021 to © The Author(s) 2020 and the article is forthwith distributed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0
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