bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of the Heparin‐Based Anticoagulant Drug Fondaparinux
Authors: Chang Cheng‐Hsiu , Lico Larry S. , Huang Teng‐Yi , Lin Shu‐Yi , Chang Chi‐Liang , Arco Susan D. , Hung Shang‐Cheng 
Published: July 2014

AbstractFondaparinux, a synthetic pentasaccharide based on the heparin antithrombin‐binding domain, is an approved clinical anticoagulant. Although it is a better and safer alternative to pharmaceutical heparins in many cases, its high cost, which results from the difficult and tedious synthesis, is a deterrent for its widespread use. The chemical synthesis of fondaparinux was achieved in an efficient and concise manner from commercially available D‐glucosamine, diacetone α‐D‐glucose, and penta‐O‐acetyl‐D‐glucose. The method involves suitably functionalized building blocks that are readily accessible and employs shared intermediates and a series of one‐pot reactions that considerably reduce the synthetic effort and improve the yield.
Synthesis of Densely Phosphorylated Bis‐1,5‐Diphospho‐myo‐Inositol Tetrakisphosphate and its Enantiomer by Bidirectional P‐Anhydride Formation
Authors: Capolicchio Samanta , Wang Huanchen , Thakor Divyeshsinh T. , Shears Stephen B. , Jessen Henning J. 
Published: July 2014

AbstractThe ubiquitous mammalian signaling molecule bis‐diphosphoinositol tetrakisphosphate (1,5‐(PP)2‐myo‐InsP4, or InsP8) displays the most congested three‐dimensional array of phosphate groups found in nature. The high charge density, the accumulation of unstable P‐anhydrides and P‐esters, the lack of UV absorbance, and low levels of optical rotation constitute severe obstacles to its synthesis, characterization, and purification. Herein, we describe the first procedure for the synthesis of enantiopure 1,5‐(PP)2‐myo‐InsP4 and 3,5‐(PP)2‐myo‐InsP4 utilizing a C2‐symmetric P‐amidite for desymmetrization and concomitant phosphitylation followed by a one‐pot bidirectional P‐anhydride‐forming reaction that combines sixteen chemical transformations with high efficiency. The configuration of these materials is unambiguously shown by subsequent X‐ray analyses of both enantiomers after being individually soaked into crystals of the kinase domain of human diphosphoinositol pentakisphosphate kinase 2.
High‐Performance Hole‐Extraction Layer of Sol–Gel‐Processed NiO Nanocrystals for Inverted Planar Perovskite Solar Cells
Authors: Zhu Zonglong , Bai Yang , Zhang Teng , Liu Zhike , Long Xia , Wei Zhanhua , Wang Zilong , Zhang Lixia , Wang Jiannong , Yan Feng , Yang Shihe 
Published: July 2014

AbstractHybrid organic/inorganic perovskite solar cells have been rapidly evolving with spectacular successes in both nanostructured and thin‐film versions. Herein, we report the use of a simple sol–gel‐processed NiO nanocrystal (NC) layer as the hole‐transport layer in an inverted perovskite solar cell. The thin NiO NC film with a faceted and corrugated surface enabled the formation of a continuous and compact layer of well‐crystallized CH3NH3PbI3 in a two‐step solution process. The hole‐extraction and ‐transport capabilities of this film interfaced with the CH3NH3PbI3 film were higher than those of organic PEDOT:PSS layers. The cell with a NiO NC film with a thickness of 30–40 nm exhibited the best performance, as a thinner layer led to a higher leakage current, whereas a thicker layer resulted in a higher series resistance. With the NiO film, we observed a cell efficiency of 9.11 %, which is by far the highest reported for planar perovskite solar cells based on an inorganic hole‐extracting layer.
Synthesis and Duplex‐Stabilizing Properties of Fluorinated N‐Methanocarbathymidine Analogues Locked in the C3′‐endo Conformation
Authors: Jung Michael E. , Dwight Timothy A. , Vigant Frederic , Østergaard Michael E. , Swayze Eric E. , Seth Punit P. 
Published: July 2014

AbstractThe efficient synthesis, antiviral activity, and duplex‐stabilizing properties of both isomers of the 2′‐fluoro analogue of Northern methanocarbathymidine (N‐MCT), 2 and 3, are reported. We show that 2′‐F incorporation on the N‐MCT scaffold has a strong stabilizing effect on duplex thermal stability.
Langmuir Analysis of Nanoparticle Polyvalency in DNA‐Mediated Adsorption
Authors: O'Brien Matthew N. , Radha Boya , Brown Keith A. , Jones Matthew R. , Mirkin Chad A. 
Published: July 2014

AbstractMany nanoparticle adsorption processes are dictated by the collective interactions of surface‐bound ligands. These adsorption processes define how nanoparticles interact with biological systems and enable the assembly of nanoparticle‐based materials and devices. Herein, we present an approach for quantifying nanoparticle adsorption thermodynamics in a manner that satisfies the assumptions of the Langmuir model. Using this approach, we study the DNA‐mediated adsorption of polyvalent anisotropic nanoparticles on surfaces and explore how deviations from model assumptions influence adsorption thermodynamics. Importantly, when combined with a solution‐based van’t Hoff analysis, we find that polyvalency plays a more important role as the individual interactions become weaker. Furthermore, we find that the free energy of anisotropic nanoparticle adsorption is consistent across multiple shapes and sizes of nanoparticles based on the surface area of the interacting facet.
CXCR4‐Targeted and MMP‐Responsive Iron Oxide Nanoparticles for Enhanced Magnetic Resonance Imaging
Authors: Gallo Juan , Kamaly Nazila , Lavdas Ioannis , Stevens Elizabeth , Nguyen Quang‐De , Wylezinska‐Arridge Marzena , Aboagye Eric O. , Long Nicholas J. 
Published: July 2014

AbstractMRI offers high spatial resolution with excellent tissue penetration but it has limited sensitivity and the commonly administered contrast agents lack specificity. In this study, two sets of iron oxide nanoparticles (IONPs) were synthesized that were designed to selectively undergo copper‐free click conjugation upon sensing of matrix metalloproteinase (MMP) enzymes, thereby leading to a self‐assembled superparamagnetic nanocluster network with T2 signal enhancement properties. For this purpose, IONPs with bioorthogonal azide and alkyne surfaces masked by polyethylene glycol (PEG) layers tethered to CXCR4‐targeted peptide ligands were synthesized and characterized. The IONPs were tested in vitro and T2 signal enhancements of around 160 % were measured when the IONPs were incubated with cells expressing MMP2/9 and CXCR4. Simultaneous systemic administration of the bioorthogonal IONPs in tumor‐bearing mice demonstrated the signal‐enhancing ability of these ‘smart’ self‐assembling nanomaterials.
A new strategy for plasticizing and stabilization of PVC mixtures
Authors: Kalousková Radka , Fartáková Helena , Malinová Lenka , Brožek Jiří 
Published: July 2014

ABSTRACTThis study was undertaken to examine possible use of classic tetravalent tin‐based heat stabilizers for the preparation of a polymer plasticizer: poly(ε‐caprolactone) (PCL) and simultaneous stabilization of PVC in PVC/PCL mixtures. PCL was prepared from ε‐caprolactone (CL) by polymerization initiated by tin‐containing organic compounds and successfully used to simultaneously plasticize and stabilize PVC. Moreover, conditions under which the polymerization of CL took place directly in situ during PVC/CL mixture processing were found. The procedure yielded homogeneous plasticized PVC/PCL mixtures, which were stable and contained >90% of the original monomer content. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41066.
Synthesis and In vitro cytotoxicity of poly(ethylene glycol)–epothilone B conjugates
Authors: Zhang Haiyan , Wang Kun , Cheng Xiaochen , Lu Yuxin , Zhang Qinglin 
Published: July 2014

ABSTRACTNatural epothilone B (EPOB) is currently in clinical trials for treatment of advanced cancers. In this study, two poly(ethylene glycol) (PEG)–EPOB conjugates were synthesized with carbodiimide chemistry with linear PEG Methoxy‐PEG‐Carboxymethy(mPEG‐COOH) with different molecular weights (5 and 20 kDa). The products were confirmed by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectroscopy and 1H‐NMR, which showed that PEGylation only took place at the 7‐OH site of EPOB. The solubilities of PEG5K–EPOB the conjugate of mPEG‐COOH (MW 5,000) and epothilone B and PEG20K–EPOB the conjugate of mPEG‐COOH (MW 20,000) and epothilone B were determined to be 4.93 × 10−2 and 1.58 × 10−2 mmol/mL; this showed improvements of 35 and 11 times, respectively, over that of free EPOB (1.4 × 10−3 mmol/mL). Moreover, the conjugates were more stable than that of free EPOB in plasma. The cytotoxicity of conjugates was evaluated on human breast cancer MCF‐7 cells with an 3‐(4,5)‐dimethylthiahiazo (‐z‐y1)‐3,5‐di‐ phenytetrazoliumromide(MTT) based assay. The half maximal inhibitory concentration of a substance(IC50) values of EPOB, PEG5K–EPOB, and PEG20K–EPOB were 6.0 × 10−4, 0.57, and 8.4 × 10−3 μM, respectively. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41123.
Nanocomposites based on MWCNT and polystyrene, styrene‐acrylonitrile copolymer, or polymethylmethacrylate, obtained by miniemulsion polymerization
Authors: Donescu Dan , Corobea Mihai Cosmin , Petcu Cristian , Spataru Catalin Ilie , Ghiurea Marius , Somoghi Raluca , Gabor Raluca , Thomassin Jean‐Michel , Alexandre Michaël , Jerome Christine 
Published: July 2014

ABSTRACTFree radical miniemulsion polymerization of styrene (St), St/acrylonitrile 3 : 1 mixture or methylmethacrylate in the presence of multiwalled carbon nanotubes (MWCNT) was proven as a convenient way to obtain homogenous hybrids with perspectives in associated applications like foams specialties materials. Miniemulsion polymerization was viable up to 2% wt. MWCNT to monomer, without agglomerations. The grafting on MWCNT during the polymerization occurs without the need for supplementary functionalization and the polymer grafted nanotubes showed stable dispersions in the polymer solvent. Monomer polarity affected the grafting ability during the polymerization process. The nanocomposites obtained after purification and drying were used in foaming process. MWCNT presence in the related nanocomposites decreased the pore sizes in foam‐like materials (for all three different matrices). At 1 wt % MWCNT content, low density (< 0.3 g/cm3), low pore size (< 10 μm) and high cell density (>109 cell/cm3) were achieved. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41148.
Mechanical and barrier properties of thermoplastic whey protein isolate/ethylene vinyl acetate blends
Authors: Schmid Markus , Müller Kerstin , Sängerlaub Sven , Stäbler Andreas , Starck Vanessa , Ecker Felix , Noller Klaus 
Published: July 2014

ABSTRACTCrude oil is becoming scarcer and more expensive, resulting in alternative biobased or partially biobased materials gaining importance in the field of plastic packaging and encouraging the development of naturally derived, protein‐based plastics (Endres, 2009; Jones and McClements, Compreh. Rev. Food Sci. Food Safety 2010, 9, 374; Khwaldia et al., Compreh. Rev. Food Sci. Food Safety 2010, 9, 374). A strategy to improve extrusion processing behavior of proteins is the blending with other polymers. In this study ethylene vinyl acetate (EVA) was used for such purpose. The aim of this study was to determine the properties of blends of thermoplastic whey protein (TPP) and ethylene vinyl acetate (EVA). Mechanical and barrier properties were tested. Blends of differing TPP/EVA ratio were produced and extruded into flat films. Morphological analysis of the blends shows immiscibility of the TPP and EVA, greatly influencing the mechanical properties. Young's modulus measurements shows the values approached that of pure EVA with increasing EVA ratios. At values of about 21 MPa, corresponding to EVA ratios of 30% (w/w) and above, continuous extrusion including material take‐off was possible. At higher whey protein ratios in the blends the water vapor transmission rate increased, i.e., the higher water vapor transmission rate of whey protein compared with EVA dominated this property. This study showed that whey proteins can be utilized for extrusion by blending with EVA. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41172.
Cell morphology, bubbles migration, and flexural properties of non‐uniform epoxy foams using chemical foaming agent
Authors: Wang Lijun , Yang Xu , Jiang Tuanhui , Zhang Chun , He Li 
Published: July 2014

ABSTRACTEpoxy foams with different densities and microstructures were prepared by changing the process parameters including the foaming temperature, chemical foaming agent (CFA) content and precuring extent. The microstructure of foams reveals a smaller cell size, higher cell density, and more homogeneous distribution of cells at higher precuring extent. However, the cell size and distribution are not affected by the foaming temperature and CFA content without precuring process. In addition, the bubbles migration, which resulted in non‐uniform cell density distribution, was promoted by increasing the foaming temperature and depressed by increasing the CFA content and precuring extent. The flexural properties of the non‐uniform epoxy foams were also studied. Results showed that the flexural modulus was related to the cell morphology, while the flexural strength was affected by both the cell morphology and the position of the specimens during test. It was also found that the relative flexural modulus and strength exhibited a power‐law dependence with respect to the relative density. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41175.
Fabrication of the self‐reinforced composites using co‐extrusion technique
Authors: Andrzejewski Jacek , Szostak Marek , Barczewski Mateusz , Krasucki Janusz , Sterzynski Tomasz 
Published: July 2014

ABSTRACTThe results of this work relate to the use of co‐extrusion technology in the preparation of monocomposite pellets. The low‐melting polypropylene copolymer was used as a matrix material. The high strength polypropylene fibers were used as a fibrous reinforcement. Research confirms the possibility to produce the pellets with fibrous structure. The prepared composite material in the form of pellets was processed and shaped using the injection molding technology. Obtained samples were subjected to mechanical testing in the static tensile test and dynamic mechanical analysis. Research complements microscopic observation of scanning electron microscopy. The measurement results confirm the reinforcing effect of the fibers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41180.
Effect of poly(ethylene glycol) on the properties and foaming behavior of macroporous poly(lactic acid)/sodium chloride scaffold
Authors: Chen Bin‐Yi , Wang Yuan‐Sheng , Mi Hao‐Yang , Yu Peng , Kuang Tai‐Rong , Peng Xiang‐Fang , Wen Jing‐Song 
Published: July 2014

ABSTRACTIn this study, we prepared poly(lactic acid) (PLA)/poly(ethylene glycol) (PEG)/sodium chloride (NaCl) blends by melt blending with a triple‐screw dynamic extruder. The effects of PEG on the thermal property, mechanical property, and morphology of blends were investigated in detail. It was found that the incorporation of PEG and NaCl significantly improved the crystallization rate, elongation at break, surface adhesion, and reduced viscoelasticity of PLA. The blends were further batch‐foamed at different temperatures with supercritical carbon dioxide to study the foaming properties. The results of PLA/PEG/NaCl (50 : 10 : 40 wt %) composites after foaming and particle leaching revealed that an interconnected bimodal porous scaffold with the highest porosity of 89% could be achieved. Furthermore, the addition of PEG can significantly reduce the water contact angle so as to enhance the wetting ability of the scaffolds. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41181.
Meticulous analysis and consequences of microstructure changes on melt rheology and dynamic viscoelasticity of thermoplastic vulcanizates upon reprocessing
Authors: Dey Pranab , Naskar Kinsuk , Nando Golok B. , Dash Biswaranjan , Nair Sujith , Unnikrishnan G. 
Published: July 2014

ABSTRACTThermoplastic vulcanizates (TPVs), which are a special class of elastomer alloy, prepared by dynamic vulcanization possess unique morphology of finely dispersed micron‐size cross‐linked elastomeric particles in a continuous thermoplastic matrix. The present study investigates the microstructure formation of elastomeric phase and its associated morphological changes during reprocessing of TPVs based on poly[styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene] triblock co‐polymer (S‐EB‐S) and solution polymerized styrene butadiene elastomer (S‐SBR) by scanning electron microscopy and atomic force microscopy. Semi‐efficient and efficient sulfur‐based curing systems have been adopted to cure the elastomeric phase and a comparative study has been made to demonstrate and explain the effect of reprocessing on the melt rheology and dynamic viscoelasticity of the TPVs. The present work also provides a better insight and guidance to control the microstructure of the cross‐linked elastomeric phase to prepare selectively co‐continuous or dispersed phase morphology. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41182.
The influence of dispersants that contain polyethylene oxide groups on the electrical resistivity of silver paste
Authors: Chiang Tzu Hsuan , Chen Yi‐Fu , Lin Ya Chun , Chen Emi Yun 
Published: July 2014

ABSTRACTThis study investigated the effects of dispersants on the electrical resistivity of silver pastes. The dispersants in the polyoxy ethylene‐p‐(1,1,3,3‐tetramethylbutyl) phenyl ethers system contain several polyethylene oxide (PEO) groups (m), which are affect the viscosity and electrical resistivity of the silver pastes. The morphologies of the cured silver pastes for different dispersants and different content were obtained by scanning electronic microscopy. In this study, octylphenol ethylene oxide condensate, poly(oxyethylene) isooctylphenyl ether (X‐100, the number of PEO groups was m = 9.5) has excellent ability to disperse silver particles. A loading of 75 wt % of silver powder was used to prepare silver paste that contained 0.8 wt % of X‐100. This paste had the lowest viscosity and the lowest electrical resistivity of cured silver paste on the indium tin oxide (ITO) film and ITO glass, i.e., 5.52 × 10−5 and 6.82 × 10−5 Ω cm. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41183.
Impact of salts on polyacrylamide hydrolysis and gelation: New insights
Authors: El Karsani Khalid S. M. , Al‐Muntasheri Ghaithan A. , Sultan Abdullah S. , Hussein Ibnelwaleed A. 
Published: July 2014

ABSTRACTPolyacrylamide (PAM) and its derivatives are the most commonly used polymers in the preparation of polymeric gels for water control in petroleum reservoirs. This study involved the use of polyethylenimine (PEI) as a crosslinker for PAM. In this study, we investigated PAM alkaline hydrolysis at high temperatures. The effects of salts [sodium chloride (NaCl) and ammonium chloride (NH4Cl)] on the degree of hydrolysis (DH) of PAM were investigated. These salts were used as retarders to elongate the gelation time of the PAM/PEI system. The data obtained from 13C‐NMR was used to understand the retardation mechanisms by salts. We found that NH4Cl accelerated the extent of hydrolysis more in comparison with NaCl. Moreover, the apparent viscosity of the hydrolyzed samples was measured. PAM hydrolysis in the presence of NH4Cl resulted in a lower solution viscosity than that in the presence of NaCl. Therefore, NH4Cl was more effective in shielding negative charges on the carboxylate groups of the partially hydrolyzed polyacrylamide (PHPA) chain. NaCl and NH4Cl were compatible with the PHPA/PEI system, but sodium carbonate showed a white precipitate. In addition, high‐temperature/high‐pressure elastic modulus data were reported for the first time for this system. Differential scanning calorimetry was coupled with rheology to explain the PAM/PEI crosslinking in the presence of salts. Models were developed to assess the impact of the salts on the PAM DH and the induction period before gelation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41185.
Biomineralized hyaluronic acid/poly(vinylphosphonic acid) hydrogel for bone tissue regeneration
Authors: Kim So Yeon , Park Jeong‐Sook 
Published: July 2014

ABSTRACTNovel biomineralized hydrogels composed of hyaluronic acid (HA) and vinyl phosphonic acid (VPAc) were designed with the aim of developing a biomimetic hydrogel system to improve bone regeneration by local delivery of a protein drug including bone morphogenetic proteins. We synthesized crosslinked hydrogels composed of methacrylated HA and poly(VPAc) [P(VPAc)], which serves as a binding site for calcium ions during the mineralization process. The HA/P(VPAc) hydrogels were biomineralized by a urea‐mediation method to create functional polymer hydrogels that can deliver the protein drug and mimic the bone extracellular matrix. The water content of the hydrogels was influenced by the HA/P(VPAc) composition, crosslinking density, biomineralization, and ionic strength of the swelling media. All HA/P(VPAc) hydrogels maintained more than 84% water content. Enzymatic degradation of HA/P(VPAc) hydrogels was dependent on the concentration of hyaluronidase and the crosslinking density of the polymer network within the hydrogel. In addition, the release behavior of bovine serum albumin from the HA/PVPAc hydrogels was mainly influenced by the drug loading content, water content, and biomineralization of the hydrogels. In a cytotoxicity study, the HA/P(VPAc) and biomineralized HA/P(VPAc) hydrogels did not significantly affect cell viability. These results suggest that biomineralized HA/P(VPAc) hydrogels can be tailored to create a biomimetic hydrogel system that promotes bone tissue repair and regeneration by local delivery of protein drugs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41194.
Role of water as a coporogen in the synthesis of mesoporous poly(divinylbenzenes)
Authors: Hanková Libuše , Holub Ladislav , Meng Xiangju , Xiao Feng‐Shou , Jeřábek Karel 
Published: July 2014

ABSTRACTThe morphology of mesoporous poly(divinylbenzenes) prepared under so called “hydrothermal” conditions and with the monomers diluted in 10 times as much porogen solvent (tetrahydrofuran with 0–20% water) was studied in both dry and swollen states, with nitrogen adsorption/desorption and inverse steric exclusion chromatography, respectively. It was found that the pore volume in the polymer examined just after preparation corresponded to the volume of the porogen used. Such a high porosity can be explained only on the basis of pore formation through microsyneresis rather than the macrosyneresis mechanism that is common in the synthesis of conventional porous polymer materials. Naturally, drying induces a pore collapse and the addition of water to the porogen influences the ability of the polymer to regain the original pore volume by reswelling in tetrahydrofuran. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41198.