167 research outputs found
Cocrystals of zonisamide: Physicochemical characterization and sustained release solid forms
No full textWe report four cocrystals of the antiepileptic drug, zonisamide (ZNS), which encounters half-life fluctuation when administered adjunctly with other antiepileptic drugs. Single crystals for two of the novel cocrystals of ZNS were successfully prepared from solvent evaporation experiments and their crystal structures were determined. Pharmaceutically acceptable cocrystals were analyzed for their dissolution rate, solubility and stability to draw conclusions on the impact of cocrystallization on the physicochemical properties of ZNS. It was found that the cocrystals showed lower solubility and dissolution rates and offer potential benefits in the development of sustained release formulations of ZNS which could address issues regarding its half-life fluctuation. Recent attempts to explore newer therapeutic applications have suggested ZNS as a potential drug for weight loss management. In this regard, the cocrystal of ZNS with caffeine, which has also been used in weight loss management, promises potential applications in the development of a novel fixed-dose combination drug which could offer synergistic therapeutic benefits in the treatment of obesity.</p
Influence of Processing and Stabilizer Selection on Microstructure, Stability and Rheology of Emulsion-Based Semisolid Formulations
No full textBackground/Objectives: Emulsion-based semisolid formulations are important delivery systems for many applications, including pharmaceuticals, cosmetics and food. The manufacturing process for such formulations typically involves a series of heating, cooling, mixing and emulsification steps. Stabilizing agents are usually included in such formulations, as emulsions are intrinsically unstable and are prone to various destabilization mechanisms. Precise control of each processing parameter and the selection of an appropriate stabilizing agent are essential for delivering products with long-term stability and the desired properties. In this study, the effects of emulsification temperature and the selection of the stabilizing agent on key product attributes were investigated to enable improved design and optimization of both the formulation and manufacturing process. Methods: Model emulsion systems containing propylene glycol (PG) as the dispersed phase and mineral oil as the continuous phase were prepared at different emulsification temperatures to cover both pre-crystallization and post-crystallization regimes. Three stabilizing agents, namely mono-and-diglyceride (MDG), neat monoglyceride (MG) and neat diglyceride (DG), were studied. Their crystallization behavior was first examined to determine crystallization temperatures and crystal morphologies. The resulting emulsion samples were then characterized in terms of their microstructure, physical stability and rheological properties. Results: The emulsions prepared under post-crystallization conditions exhibited better physical stability, higher rheological parameters (crossover stress and viscosity) and a more rigid microstructure compared to those formed under pre-crystallization conditions, regardless of the stabilizer used. Rheological properties were found to corelate well with physical stability. In the pre-crystallization regime, poor stability could partially be mitigated by lowering the emulsification temperature. MG was generally more effective than DG in stabilizing the emulsions and led to higher rheological properties, despite both crystallizing into the same polymorph within the system. This difference in performance was attributed to variations in the crystal morphology and spatial distribution within the emulsion. Notably, the MG-stabilized emulsions also displayed a self-hardening effect during storage. Conclusions: The selection of the appropriate stabilizing agents and processing conditions tailored to the specific system is critical for the successful manufacture of emulsion-based semisolid products with an optimized performance
CUHK electronic theses & dissertations collection
No full textChan, Pui Shan.Thesis M.Phil. Chinese University of Hong Kong 2014.Includes bibliographical references (leaves 88-99).Abstracts also in Chinese.Title from PDF title page (viewed on 20, September, 2016)
Reply to the ‘Comment on “Trimorphs of a pharmaceutical cocrystal involving two active pharmaceutical ingredients: potential relevance to combination drugs” by S. Aitipamula, P. S. Chow and R. B. H. Tan, <i>CrystEngComm</i>, 2009, <b>11</b>, 1823’
No full textThe inadvertent errors in the lattice energy calculations of the cocrystal polymorphs reported in our previous article were rectified.</p
Shuang ceng ji shan za ran liao ju he wu tai yang neng dian chi yan jiu
No full textPolymer solar cells (PSCs) are one of the cost-effective alternatives to the traditional silicon-based solar cell. To be commercially viable, a number of its shortfalls have to be addressed. First, the charge mobility and life time of the organic materials used in PSCs are low and results in a large series resistance and inefficient charge separation. Second, the range of absorption of light in PSCs is not wide enough to cover the whole solar spectrum. Hence, the highest power conversion efficiency (PCE) achieved by PSCs is still low compare to other types of solar cells. In this thesis, several methods were investigated to improve the PCE of PSCs base on the donor polymer Poly(3-hexylthiophene-2,5-diyl) (P3HT) and acceptor fullerene Phenyl-C61-butyric acid methyl ester (PCBM). It was found to be essential to control the drying rate of the solvent after spin-coating the polymer solution on a piece of glass as it would affect the ordering and crystallinity of the polymer chains. Besides, instead of a bulk heterojuction (BHJ) structure, a bilayer device can also give a comparable PCE by spin-coating P3HT and PCBM separately using orthogonal solvents. Factors that could affect the performance of bilayer devices, such as the drying rate and thermal annealing, were investigated. It was found that thermal annealing is essential since it would facilitate the interdiffusion of the two layers. In order to improve the range of spectral absorption of light, a squaraine dye was introduced. Squaraine has a high absorbance in the near-infrared range where the absorption is poor for P3HT. The PCE was found to increase by about 5 % by incorporating 0.5 wt % of squaraine into the BHJ system. In addition, squaraine was introduced to the bilayer system. It was found that the performance was slightly improved when squaraine was blended with PCBM in the upper layer. Various parameters were tuned to optimize the performance of this bilayer system.聚合物太陽能電池是其中一個比傳統晶體矽太陽能電池有更高成本效益的代替品。然而，聚合物太陽能電池仍然有若干缺點需要解決才能夠成為商業市場上流通的產品。首先，聚合物太陽能電池所使用的有機材料的電荷遷移率和壽命低，造成較大的串聯電阻和低效率的電荷分離。其次，聚合物太陽能電池的吸收光譜範圍較窄，不足以覆蓋整個太陽光譜。因此，相比起其他類型的太陽能電池，聚合物太陽能電池的最高能量轉換效率仍然偏低。在本論文中，我們建基於供體P3HT和受體PCBM' 進行了多分面的研究。我們發現旋塗聚合物溶液後，控制溶劑的乾燥速度是很重要的，因為這會影響聚合物鏈的排序和結晶度。另外，除了體異質接面結構外，利用正交溶劑來分別旋塗P3HT和PCBM的雙層結構亦可得到可比的最高能量轉換效率。我們研究了數個可能影響雙層結構聚合物太陽能電池效能的因素，例如乾燥速度和熱退火處理，並發現熱退火處理是非常重要，因為熱退火可以有利於兩層聚合物的相互擴散。為了擴闊電池的吸收光譜範圍，我們引入了方酸染料。方酸在近紅外線範圍內具有高的吸光率，而在此範圍內P3HT的吸光率都欠佳。在慘雜0.5重量百分比的方酸到原有的體異質接面結構後，最高能量轉換效率提升了大約百分之五。此外，方酸也才參雜到雙層結構系統內，結果發現，當方酸慘雜在上層中的PCBM後，電池的效能稍有改善。我們調整了各種參數，以完善該雙層系統的效能。Chow, Chun Yin = 雙層及摻雜染料聚合物太陽能電池研究 / 周俊然.Thesis M.Phil. Chinese University of Hong Kong 2015.Includes bibliographical references (leaves 90-92).Abstracts also in Chinese.Title from PDF title page (viewed on 07, October, 2016).Chow, Chun Yin = Shuang ceng ji shan za ran liao ju he wu tai yang neng dian chi yan jiu / Zhou Junran.Detailed summary in vernacular field only
My Beloved ; A Battle at the River Harbour
No full text《古今一美人》。主演：張活游、吳碧君、黃菊樓、鄧丹平、黃君熊、司徒英、何楚君、何少珊、潘少培、李寶倫、周家儂Cast of My Beloved: Cheung Wood Yau, Ng Bik Kwun, Wong Kuk Lau, Tang Dan Ping, Wong Kwun Hung, Szeto Ying, Ho Cho Kwun, Ho Siu Shan, Poon Siu Pui, Lee Bo Lun, Chow Ka Nung《雷炸江灣月》。主演：白玉棠、曾三多、林超群、李艷秋、龐順堯、張活游、吳碧君、何少珊Cast of A Battle at the River Harbour: Pak Yuk Tong, Tsang Sam To, Lam Chiu Kwun, Lee Yim Chau, Pong Shun Yiu, Cheung Wood Yau, Ng Bik Kwun, Ho Siu Shan興中華劇團。丁丑十一月廿六日 (28th December 1937) 利舞台開演日演《古今一美人》。主演：張活游、吳碧君、黃菊樓、鄧丹平、黃君熊、司徒英、何楚君、何少珊、潘少培、李寶倫、周家儂夜演《雷炸江灣月》。麥嘯霞特編；主演：白玉棠、曾三多、林超群、李艷秋、龐順堯、張活游、吳碧君、何少
Understanding the Salt-Dependent Outcome of Glycine Polymorphic Nucleation
No full textThe salt-dependent polymorphs of glycine crystals formed from bulk solutions have been a longstanding riddle. In this study, in order to shed fresh light, we studied the effects of seven common salts on primary nucleation of the metastable α-glycine and the stable γ-glycine. Our nucleation experiments and in-depth data analyses enabled us to reveal that (NH4)2SO4, NaCl and KNO3, in general, promote γ-glycine primary nucleation very significantly while simultaneously inhibiting α-glycine primary nucleation, thereby explaining why these three salts induce γ-glycine readily. In comparison, Ca(NO3)2 and MgSO4 also promote γ-glycine and inhibit α-glycine primary nucleation but not sufficiently to induce γ-glycine. More interestingly, Na2SO4 and K2SO4 promote not only γ-glycine but also α-glycine primary nucleation, which is unexpected and presents a rare case where a single additive promotes the nucleation of both polymorphs. As a result, the promoting effects of Na2SO4 and K2SO4 on γ-glycine do not enable γ-glycine nucleation to be more competitive than α-glycine nucleation, with γ-glycine failing to appear. These observations help us to better understand salt-governed glycine polymorphic selectivity
Design Space for Polymorphic Co-crystallization: Incorporating Process Model Uncertainty and Operational Variability
No full textDeveloping Eco-Friendly Skin Care Formulations with Microemulsions of Essential Oil
No full textWith the rising public awareness of environmental issues, consumers are increasingly demanding skin care products that create less environmental impact but still provide the same or even greater efficacy. In the skin care arena, microemulsions have been receiving increased attention as the promising delivery technology of skin care actives. Essential oils such as peppermint oil, lavender oil and eucalyptus oil are purported to have excellent antioxidant and antimicrobial properties that could be used as the eco-friendly alternatives for synthetic antioxidants and preservatives in the skin care formulations. This work therefore seeks to develop eco-friendly skin care formulations based on microemulsions of essential oil. Peppermint oil, lavender oil and eucalyptus oil were used as the oil phase to formulate naringin-loaded microemulsions, which demonstrated similar or better antioxidant and antimicrobial properties compared to the synthetic ones. When formulated into gel form, naringin-loaded microemulsion-gel formulations showed enhanced stability and release profile over their unformulated counterpart. Hence, microemulsions of essential oil developed in this work conferred a 4-fold benefits to the skin care formulations: (1) improved release (membrane permeation) of skin care active, (2) improved stability of skin care active, (3) as an eco-friendly alternative to synthetic antioxidant, and (4) a self-preserving system
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