http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Strain path effects on the microstructure evolution and mechanical properties of Zr702
Cao, W.Q.,Yu, S.H.,Chun, Y.B.,Yoo, Y.C.,Lee, C.M.,Shin, D.H.,Hwang, S.K. Elsevier 2005 Materials science & engineering. properties, micro Vol.395 No.1
<P><B>Abstract</B></P><P>A commercial-purity Zr702 was grain-refined from 20μm to 0.2–0.5μm by equal channel angular pressing. Grain refinement was most evident in the first pass but was insignificant during the subsequent passes. Two microstructural characteristics evolved: a lamellar structure and an equiaxed subgrain structure during the route A pressing and the route B<SUB>C</SUB> pressing, respectively. Due to the rotation of specimen in between passes, two sets of geometrically necessary boundaries were formed during the route B<SUB>C</SUB> pressing. The mechanism of grain refinement during the route A pressing was evolution of high-angle geometrically necessary boundaries from the low-angled ones, while that during the route B<SUB>C</SUB> pressing was decomposition and rearrangement of pre-existing boundaries. The yield stress of severely deformed specimens increased with the reducing grain size according to a Hall–Petch relationship.</P>
Cao, Q.R.,Choi, Y.W.,Cui, J.H.,Lee, B.J. Elsevier Science Publishers 2005 Journal of controlled release Vol.108 No.2
Effect of incorporating pharmaceutical excipients on the in vitro release profiles and the release mechanism of monolithic hydroxypropylmethylcellulose (4000 cps) matrix tablets (m-HPMC tablets) in terms of mimicking the dual drug release character of bi-layered Tylenol® ER tablets was studied. We also compared the in vitro release profiles of optimized m-HPMC matrix tablet and Tylenol® ER tablet in water, pH 1.2 gastric fluid, and pH 6.8 intestinal fluid, and in vivo drug bioavailabilities in healthy human volunteers. Acetaminophen was used as the model drug. The m-HPMC tablets were prepared using a wet granulation method followed by direct compression. Release profiles and swelling rates of m-HPMC tablets were found to be highly influenced by the types and amounts of pharmaceutical excipients incorporated. Starch 1500 (Prejel®) and sodium lauryl sulfate (SLS) played a key role in determining the dissolution rate of m-HPMC tablets. Additional excipients, i.e., microcrystalline cellulose (Avicel® PH101) and NaH<SUB>2</SUB>PO<SUB>4</SUB> were used to tune the release profiles of m-HPMC tablets. The effect of pharmaceutical excipients on drug release from HPMC-based matrix tablets was found to be mainly due to a change in hydrophilic gel expansion and on physical interactions between the drug and HPMC. The optimized m-HPMC tablet with a balanced ratio of Prejel®, SLS, Avicel® PH101, and NaH<SUB>2</SUB>PO<SUB>4</SUB> in the formulation showed dual release profiles in water, pH 1.2 gastric fluid, and pH 6.8 intestinal fluid in vitro. Dual release was defined as immediate drug release within few minutes followed by extended release over 8 h. The similarity factors of m-HPMC tablets and bi-layered Tylenol® ER tablets were 79.8, 66.1, and 82.7 in water, gastric fluid and intestinal fluid, respectively, indicating the equivalence of the two release profiles. No significant in vivo bioavailability differences were observed in healthy human volunteers. The developed m-HPMC tablet with dual release characteristics can be easily prepared using a conventional high-speed tablet machine and could provide an alternative to commercially available bilayered Tylenol® ER tablets.
Xuan Thang Cao,Maheshkumar Prakash Patil,Quoc Thang Phan,Cuong M.Q. Le,Byung-Hyun Ahn,GUN-DO KIM,임권택 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.83 No.-
This paper reports a green and direct functionalization of poly(ethylene glycol)-graft-[furfuryl-graft-(poly(styrene-alt-maleic anhydride))] (PEG-PSMF) on the surface of single walled carbon nanotubes (SWCNTs)in aqueous media through Diels-Alder (DA) click reaction. Firstly, novel PEG grafted, furfurylfunctionalized copolymers were prepared by RAFT polymerization followed by ring opening reactions. The functional copolymer was simply grafted on SWCNTs by DA reaction at room temperature underultrasonication. The resulting hybrid materials were characterized by 1H NMR, GPC, UV–vis, FT-IR, TGA,TEM, and DLS. The hybrid materials possessed a high drug loading capacity (DLC) of doxorubicin (DOX),which could reach up to 279.9 wt.% of DLC. Moreover, in vitro drug release profiles showed that drugrelease rate at pH 5.5 under an acidic condition of tumor cell microenvironment was much higher than atpH 7.4 of the physiological condition. MTT assays demonstrated that the hybrid materials did not haveany practical cytotoxicity against the normal HEK293 cell line, while drug loaded hybrids displayed a highantitumor activity towards HeLa cancer cells. This strategy offers a promising SWCNT-based drug carrierfor tumor-targeted chemotherapy.
Influence of Molecular Coherence on Surface Viscosity
Choi, Siyoung Q.,Kim, Kyuhan,Fellows, Colin M.,Cao, Kathleen D.,Lin, Binhua,Lee, Ka Yee C.,Squires, Todd M.,Zasadzinski, Joseph A. American Chemical Society 2014 Langmuir Vol.30 No.29
<P/><P>Adding small fractions of cholesterol decreases the interfacial viscosity of dipalmitoylphosphatidylcholine (DPPC) monolayers by an order of magnitude per wt %. Grazing incidence X-ray diffraction shows that cholesterol at these small fractions does not mix ideally with DPPC but rather induces nanophase separated structures of an ordered, primarily DPPC phase bordered by a line-active, disordered, mixed DPPC-cholesterol phase. We propose that the free area in the classic Cohen and Turnbull model of viscosity is inversely proportional to the number of molecules in the coherence area, or product of the two coherence lengths. Cholesterol significantly reduces the coherence area of the crystals as well as the interfacial viscosity. Using this free area collapses the surface viscosity data for all surface pressures and cholesterol fractions to a universal logarithmic relation. The extent of molecular coherence appears to be a fundamental factor in determining surface viscosity in ordered monolayers.</P>
Cuong M.Q. Le,Xuan Thang Cao,정연태,임권택 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.64 No.-
Imidazolium-based poly(ionic liquid)s grafted on the surface of multiwalled carbon nanotubes (MWNTs) were prepared by Diels–Alder “click” reaction with a high grafting density. Poly(styrene-alt-maleic anhydride) (PSM) was functionalized with furfuryl amine and then it was modified with 1-(3-aminopropyl)-3-methylimidazolium bromide to produce poly(ionic liquid)s functionalized with furfuryl groups (PSMF-ILs). PSMF-ILs were directly grafted onto the surface of MWNTs under ultrasonication to form PSMF-IL/MWNT nanocomposites. The material was characterized by FTIR, Raman spectroscopy, XRD, XPS and TEM analyses. The results showed that a very high grafting density was achieved in deep eutectic solvents based on choline chloride:ethylene glycol in a short time.