bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dual xanthan gum/poly(vinyl acetate) or alkyl‐functionalized poly(vinyl alcohol) films as models for advanced coatings
Authors: Puga Alberto V. , Garcia‐Valls Ricard , Fernández‐Prieto Susana , Smets Johan , York David 
Published: May 2014

ABSTRACTDouble‐layer films, prepared by casting films of xanthan gum (XG), and subsequently poly(vinyl acetate) (PVAc) onto the former, are reported. The resulting XG/PVAc films provide high protection as coatings to a bleaching agent, 6‐(phthalimido)peroxyhexanoic acid, in liquid detergents, due to the combined roles of the outer PVAc layer as water‐barrier and the inner XG layer as water‐sink. PVAc films cast from either homogeneous solutions in acetone or aqueous dispersions were used; the stabilities exerted by the former were markedly superior. For comparison, poly(vinyl alcohol) (PVA) was also used as outer wall material, resulting in much lower protection due to its hydrophilicity. Functionalization (silylation or acetalyzation) of PVA films is also suggested as a means to decrease the surface hydrophilicity of the material. The dual hydrophilic–hydrophobic films presented herein serve as models for advanced coatings in (micro)encapsulation processes, owing to the straightforward study of their morphology and transport phenomena. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40870.
Oligolysine‐Conjugated Zinc(II) Phthalocyanines as Efficient Photosensitizers for Antimicrobial Photodynamic Therapy
Authors: Ke Mei‐Rong , Eastel Jennifer Mary , Ngai Karry L. K. , Cheung Yuk‐Yam , Chan Paul K. S. , Hui Mamie , Ng Dennis K. P. , Lo Pui‐Chi 
Published: May 2014

AbstractA series of zinc(II) phthalocyanines conjugated with an oligolysine chain (n=2, 4, and 8) were synthesized and characterized by using various spectroscopic methods. As shown by using UV/Vis and fluorescence spectroscopic methods, these compounds were nonaggregated in N,N‐dimethylformamide, and gave a weak fluorescence emission and high singlet oxygen quantum yield (ΦΔ=0.86–0.89) as a result of their di‐α‐substitution. They became slightly aggregated in water with 0.05 % Cremophor EL, but they could still generate singlet oxygen effectively. The antimicrobial photodynamic activities of these compounds were then examined against various bacterial strains, including the Gram‐positive methicillin‐sensitive Staphylococcus aureus ATCC 25923 and methicillin‐resistant Staphylococcus aureus ATCC BAA‐43, and the Gram‐negative Escherichia coli ATCC 35218 and Pseudomonas aeruginosa ATCC 27853. Generally, the dyes were much more potent toward the Gram‐positive bacteria. Only 15 to 90 nM of these photosensitizers was required to induce a 4 log reduction in the cell viability of the strains. For Escherichia coli, the photocytotoxicity increased with the length of the oligolysine chain. The octalysine derivative showed the highest potency with a 4 log reduction concentration of 0.8 μM. Pseudomonas aeruginosa was most resistant to the photodynamic treatment. The potency of the tetralysine derivative toward a series of clinical strains of Staphylococcus aureus was also examined and found to be comparable with that toward the nonclinical counterparts. Moreover, the efficacy of these compounds in photodynamic inactivation of viruses was also examined. They were highly photocytotoxic against the enveloped viruses influenza A virus (H1N1) and herpes simplex virus type 1 (HSV1), but exhibited no significant cytotoxicity against the nonenveloped viruses adenovirus type 3 (Ad3) or coxsackievirus (Cox B1). The octalysine derivative also showed the highest potency with an IC50 value of 0.05 nM for the two enveloped viruses.
Photodegradable Neutral–Cationic Brush Block Copolymers for Nonviral Gene Delivery
Authors: Hu Xianglong , Li Yang , Liu Tao , Zhang Guoying , Liu Shiyong 
Published: May 2014

AbstractWe report on the fabrication of a photodegradable gene‐delivery vector based on PEO‐b‐P(GMA‐g‐PDMAEMA) neutral–cationic brush block copolymers that possess cationic poly(N,N‐dimethylaminoethyl methacrylate) (PDMAEMA) brushes for DNA compaction, poly(ethylene oxide) (PEO) as a hydrophilic block, and poly(glycidyl methacrylate) (PGMA) as the backbone. The PEO‐b‐P(GMA‐g‐PDMAEMA) copolymers were synthesized through the combination of reversible addition–fragmentation transfer (RAFT) polymerization and postmodification. A photocleavable PEO‐based macroRAFT agent was first synthesized; next, the PEO‐b‐PGMA block copolymer was prepared by RAFT polymerization of GMA; this was followed by a click reaction to introduce the RAFT initiators on the side chains of the PGMA block; then, RAFT polymerization of DMAEMA afforded the PEO‐b‐P(GMA‐g‐PDMAEMA) copolymer. The obtained neutral–cationic brush block copolymer could effectively complex plasmid DNA (pDNA) into nanoparticles at an N/P ratio (i.e., the number of nitrogen residues per DNA phosphate) of 4. Upon UV irradiation, pDNA could be released owing to cleavage of the pDNA‐binding cationic PDMAEMA side chains as well as the nitrobenzyl ester linkages at the diblock junction point. In addition, in vitro gene transfection results demonstrated that the polyplexes could be effectively internalized by cells with good transfection efficiency, and the UV irradiation protocol could considerably enhance the efficiency of gene transfection.
Involvement of intestinal permeability in the oral absorption of clarithromycin and telithromycin
Authors: Togami Kohei , Hayashi Yoshiaki , Chono Sumio , Morimoto Kazuhiro 
Published: May 2014

ABSTRACTThe involvement of intestinal permeability in the oral absorption of clarithromycin (CAM), a macrolide antibiotic, and telithromycin (TEL), a ketolide antibiotic, in the presence of efflux transporters was examined. In order independently to examine the intestinal and hepatic availability, CAM and TEL (10 mg/kg) were administered orally, intraportally and intravenously to rats. The intestinal and hepatic availability was calculated from the area under the plasma concentration–time curve (AUC) after administration of CAM and TEL via different routes. The intestinal availabilities of CAM and TEL were lower than their hepatic availabilities. The intestinal availability after oral administration of CAM and TEL increased by 1.3‐ and 1.6‐fold, respectively, after concomitant oral administration of verapamil as a P‐glycoprotein (P‐gp) inhibitor. Further, anin vitrotransport experiment was performed using Caco‐2 cell monolayers as a model of intestinal epithelial cells. The apical‐to‐basolateral transport of CAM and TEL through the Caco‐2 cell monolayers was lower than their basolateral‐to‐apical transport. Verapamil and bromosulfophthalein as a multidrug resistance‐associated proteins (MRPs) inhibitor significantly increased the apical‐to‐basolateral transport of CAM and TEL. Thus, the results suggest that oral absorption of CAM and TEL is dependent on intestinal permeability that may be limited by P‐gp and MRPs on the intestinal epithelial cells. Copyright © 2014 John Wiley & Sons, Ltd.
DNA‐Scaffolded Multivalent Ligands to Modulate Cell Function
Authors: Zhang Zhiqing , Eckert Mark A. , Ali M. Monsur , Liu Linan , Kang Dong‐Ku , Chang Elizabeth , Pone Egest J. , Sender Leonard S. , Fruman David A. , Zhao Weian 
Published: May 2014

AbstractWe report a simple, versatile, multivalent ligand system that is capable of specifically and efficiently modulating cell‐surface receptor clustering and function. The multivalent ligand is made of a polymeric DNA scaffold decorated with biorecognition ligands (i.e., antibodies) to interrogate and modulate cell receptor signaling and function. Using CD20 clustering‐mediated apoptosis in B‐cell cancer cells as a model system, we demonstrated that our multivalent ligand is significantly more effective at inducing apoptosis of target cancer cells than its monovalent counterpart. This multivalent DNA material approach represents a new chemical biology tool to interrogate cell receptor signaling and functions and to potentially manipulate such functions for the development of therapeutics.
Long non‐coding RNAs with low expression levels in cells are enriched in secreted exosomes
Authors: Gezer Ugur , Özgür Emre , Cetinkaya Merve , Isin Mustafa , Dalay Nejat 
Published: May 2014

AbstractLong non‐coding RNAs (lncRNAs) are involved in regulating chromatin modifications, gene transcription, mRNA translation, and protein function. We recently reported a high variation in the basal expression levels of a panel of lncRNAs in HeLa and MCF‐7 cells and their differential response to DNA damage induction. Here, we hypothesized that lncRNA molecules with different cellular expression may have a differential abundance in secreted exosomes, and their exosome levels would reflect cellular response to DNA damage. MALAT1, HOTAIR, lincRNA‐p21, GAS5, TUG1, CCND1‐ncRNA in exosomes secreted from cultured cells were characterized. A different expression pattern of lncRNAs in exosomes was seen compared to cells. RNA molecules with relative low expression levels (lincRNA‐p21, HOTAIR, ncRNA‐CCND1) were highly enriched in exosomes. TUG1 and GAS5 levels were moderately elevated in exosomes, whereas MALAT1—which was the most abundant molecule in cells—was present at levels comparable to its cellular levels. lincRNA‐p21 and ncRNA‐CCND1 were the main molecules; exosome levels of them best reflect the change of their cellular levels upon exposure of the cells to bleomycin‐induced DNA damage. In conclusion, we provide evidence that lncRNAs have a differential abundance in exosomes, indicating a selective loading.
A First‐Principles Study of Carbon–Oxygen Bond Scission in Multiatomic Molecules on Flat and Stepped Metal Surfaces
Authors: Zhao Yong‐Hui , Liu Jin‐Xun , Su Hai‐Yan , Sun Keju , Li Wei‐Xue 
Published: May 2014

AbstractStep sites over terrace sites have been suggested to be the active sites in many catalytic reactions particularly bond breaking of diatomic molecules. Aiming to provide insight into the role of step sites in multiatomic molecules bond breaking reactions and their dependence on catalysts, we present herein a systematic first‐principles study of carbon–oxygen bond scission of diatomic CO and multiatomic HCO and CH3HCO on flat and stepped Co, Rh, and Ir surfaces. We find that multiatomic molecules exhibit distinct carbon–oxygen scission activity from diatomic molecules regardless of the metal catalysts (Co, Rh, and Ir) considered: compared to the huge enhancement of step sites for CO with a barrier 0.81–1.29 eV lower than that of flat surfaces, the role of step sites for CH3CHO is substantially weakened with a barrier 0.11–0.27 eV higher than that of flat surfaces. The reason for this is the change of adsorption configurations on flat surfaces and increase of Pauli repulsion on the congested stepped sites for the dissociation of multiatomic molecules.
Design of a Bifunctional Ir–Zr Based Metal–Organic Framework Heterogeneous Catalyst for the N‐Alkylation of Amines with Alcohols
Authors: Rasero‐Almansa A. M. , Corma A. , Iglesias M. , Sánchez F. 
Published: May 2014

AbstractThe direct N‐alkylation of amines with alcohols was performed with an Ir‐Zr‐based metal–organic framework multifunctional heterogeneous catalyst. This system is efficient and environmentally benign for the synthesis of various organic amines in air in the absence of a base. The catalyst was recovered and reused without significant loss of activity, and only water was produced as a byproduct.
Gold(I) N‐Heterocyclic Carbene Complexes with Naphthalimide Ligands as Combined Thioredoxin Reductase Inhibitors and DNA Intercalators
Authors: Meyer Andreas , Oehninger Luciano , Geldmacher Yvonne , Alborzinia Hamed , Wölfl Stefan , Sheldrick William S. , Ott Ingo 
Published: May 2014

AbstractOrganometallic conjugates consisting of a gold(I) N‐heterocyclic carbene (NHC) moiety and a naphthalimide were prepared and investigated as cytotoxic agents that interact with both DNA and the disulfide reductase enzyme thioredoxin reductase (TrxR). The complexes were potent DNA intercalators related to their naphthalimide partial structure, inhibited TrxR as a consequence of the incorporation of the gold(I) moiety, and triggered efficient cytotoxic effects in MCF‐7 breast and HT‐29 colon adenocarcinoma cells. Strong effects on tumor cell metabolism were noted for the most cytotoxic complex, chlorido[1‐(3′‐(4′′‐ethylthio‐1′′,8′′‐naphthalimid‐N′′‐yl))‐propyl‐3‐methyl‐imidazol‐2‐ylidene]gold(I) (4 d). In conclusion, the conjugation of naphthalimides with gold(I) NHC moieties provided a useful strategy for the design of bioorganometallic anticancer agents with multiple modes of action.
Dinuclear Platinum Complexes Containing Planar Aromatic Ligands to Enhance Stacking Interactions with Proteins
Authors: Ma Erin S. F. , Daniel A. Gerard , Farrell Nicholas P. 
Published: May 2014

AbstractIn an approach to design drugs with higher affinity for π–π stacking and electrostatic interactions with targeted biomolecules, complexes of the type [{cis‐Pt(A)2(L)}2‐μ‐{trans‐1,4‐dach}](NO3)4 ((A)2=(NH3)2 or ethylenediamine (en), L=quinoline (quin) or benzothiazole (bztz), dach=trans‐1,4‐diaminocyclohexane) were synthesized. The quinoline complex, [{cis‐Pt(en)(quin)}2‐μ‐(dach)](NO3)4 (9) was synthesized from the precursor K[PtCl3(quin)] (1), while the benzothiazole complexes, [{cis‐Pt(A)2(bztz)}2‐μ‐(dach)](NO3)4 ((A)2=(NH3)2 (10) and (A)2=en (11)) were synthesized from the precursors cis‐[Pt(A)2Cl(bztz)] ((A)2=(NH3)2 (7) and (A)2=en (8)). Their interactions with N‐acetyltryptophan and a model pentapeptide (N‐Ac‐WLDSW‐OH), modeled on the pentapeptide recognition sequence (FSDLW) of p53–mdm2 interaction, were examined by fluorescence spectroscopy. The dinuclear complexes were found to be significantly stronger at quenching the fluorescence of tryptophan than their mononuclear Pt‐based analogues indicating stronger binding. Molecular modeling suggests a “sandwich” mode of binding, and the flexibility of the dinuclear motif can allow the design of more selective and stronger‐binding complexes. Based on these results a further prototype, [{Pt(en)(9‐EtGua)}2μ‐H2N(CH2)6NH2]4+, incorporating the purine 9‐ethylguanine (9‐EtG) as a stacking moiety, was prepared which showed good cytotoxicity in A2780 and OsACL tumor cell lines.
Conjugates of Cisplatin and Cyclooxygenase Inhibitors as Potent Antitumor Agents Overcoming Cisplatin Resistance
Authors: Neumann Wilma , Crews Brenda C. , Marnett Lawrence J. , Hey‐Hawkins Evamarie 
Published: May 2014

AbstractCyclooxygenase‐2 (COX‐2) is an enzyme involved in tumorigenesis, and inhibitors of the enzyme are increasingly used as adjuvant modulators in anticancer therapies due to their synergistic effects with traditional chemotherapeutics. COX‐2 is also reported to cause resistance towards antitumor agents, such as cisplatin. Here, the first covalently linked conjugates of cisplatin and COX inhibitors are reported. These conjugates exhibit concerted transport of both drugs into tumor cells and simultaneous action upon intracellular cleavage. These platinum(IV) complexes show highly increased cytotoxicity compared with cisplatin and are even able to overcome cisplatin‐related resistance of tumor cells. While the results reported show that COX‐2 inhibition is not directly responsible for the potent activities of these conjugates, they do represent useful tool compounds for the elucidation of the influence of COX inhibitors on the efficacy of antitumor agents.
Emulating facial biomechanics using multivariate partial least squares surrogate models
Authors: Wu Tim , Martens Harald , Hunter Peter , Mithraratne Kumar 
Published: May 2014

SUMMARYA detailed biomechanical model of the human face driven by a network of muscles is a useful tool in relating the muscle activities to facial deformations. However, lengthy computational times often hinder its applications in practical settings. The objective of this study is to replace precise but computationally demanding biomechanical model by a much faster multivariate meta‐model (surrogate model), such that a significant speedup (to real‐time interactive speed) can be achieved. Using a multilevel fractional factorial design, the parameter space of the biomechanical system was probed from a set of sample points chosen to satisfy maximal rank optimality and volume filling. The input–output relationship at these sampled points was then statistically emulated using linear and nonlinear, cross‐validated, partial least squares regression models. It was demonstrated that these surrogate models can mimic facial biomechanics efficiently and reliably in real‐time. Copyright © 2014 John Wiley & Sons, Ltd.
Metal–Organic Framework Co(D‐Cam)1/2(bdc)1/2(tmdpy) for Improved Enantioseparations on a Chiral Cyclodextrin Stationary Phase in Gas Chromatography
Authors: Liu Hong , Xie Sheng‐Ming , Ai Ping , Zhang Jun‐Hui , Zhang Mei , Yuan Li‐Ming 
Published: May 2014

AbstractInitial efforts to combine a chiral metal–organic framework (MOF), Co(D‐Cam)1/2(bdc)1/2(tmdpy) (D‐Cam=D‐camphoric acid, bdc=1,4‐benzenedicarboxylic acid, tmdpy=4,4′‐trimethylenedipyridine), with peramylated β‐cyclodextrins to investigate whether the use of a MOF can enhance enantioseparations on a cyclodextrin stationary phase are reported. Compared with columns of peramylated β‐cyclodextrin incorporated in a MOF containing sodium chloride, the column of peramylated β‐cyclodextrin+MOF shows excellent selectivity for the recognition of racemates, and higher resolutions are achieved on the peramylated β‐cyclodextrin+MOF stationary phase. Experimental results indicate that the use of Co(D‐Cam)1/2(bdc)1/2(tmdpy) can improve enantioseparations on peramylated β‐cyclodextrins. This is the first report that chiral MOFs can improve enantioseparations on a chiral stationary phase for chromatography.
β‐Sheet Breaker Peptides Containing α,β‐Dehydrophenylalanine: Synthesis and In Vitro Activity Studies
Authors: Giordano Cesare , Punzi Pasqualina , Lori Clorinda , Chiaraluce Roberta , Consalvi Valerio 
Published: May 2014

AbstractThe synthesis and fibrillogenesis‐inhibiting activity of the new peptide derivatives 1–6, containing α,β‐unsaturated phenylalanines, are reported. These compounds are related to the pentapeptide Ac‐LPFFD‐NH2 (iAβ5p), which was designed by Soto and co‐workers and is commonly accepted as a lead compound for fibrillogenesis inhibition . Their activities are determined by Thioflavin T binding assay, far‐UV circular dichroism (CD) spectroscopy , and SEM; in addition, their structures in solution are studied through far‐UV CD and FTIR spectroscopy. The presence of two α,β‐unsaturated phenylalanines increases the fibrillogenesis inhibiting activity significantly in comparison with the lead compound. The interactions between the Aβ1–40 and the inhibitors using electrospray ionization mass spectrometry are also studied. The analyses prove the presence of noncovalent complexes of Aβ1–40 with iAβ5p and its derivatives 1–3 with stoichiometries of 1:1 and 2:1, and the results are independent of time and Aβ1–40/inhibitor ratio.
Solventless Oxidative Coupling of Amines to Imines by Using Transition‐Metal‐Free Metal–Organic Frameworks
Authors: Qiu Xuan , Len Christophe , Luque Rafael , Li Yingwei 
Published: May 2014

AbstractA highly efficient, simple, and versatile transition‐metal‐free metal–organic framework catalytic system is proposed for the oxidative coupling of amines to imines. The catalytic protocol features high activities and selectivities to target products; compatibility with a variety of substrates, including aliphatic amines and secondary amines; and the possibility to efficiently and selectively promote amine cross‐coupling reactions. A high stability and recyclability of the catalyst is also observed under the investigated conditions. Insights into the reaction mechanism indicate the formation of a superoxide species able to efficiently promote oxidative couplings.
Competing Reactions of CO2 with Cations and Anions in Azolide Ionic Liquids
Authors: Gohndrone Thomas R. , Bum Lee Tae , DeSilva M. Aruni , Quiroz‐Guzman Mauricio , Schneider William F. , Brennecke Joan F. 
Published: May 2014

AbstractWe show that phosphonium azolide ionic liquids of interest for CO2 capture applications react with CO2 both through the normal anion channel and, at elevated temperatures, through a previously unrecognized cation channel. The reaction is caused by an interaction between the anion and cation that allows proton transfer, and involves a phosphonium ylide intermediate. The cation reaction can be mitigated by using ammonium rather than phosphonium cations. Thus, phosphonium and ammonium cations paired with aprotic heterocyclic anions (AHAs) react with CO2 through different mechanisms at elevated temperatures. This work shows that careful consideration of both physical properties and chemical reactivity of ILs based on AHA anions is needed when designing ionic liquids for CO2 separations.
Balanced Gm‐C filters with improved linearity and power efficiency
Authors: Algueta‐Miguel Jose M. , De La Cruz Blas Carlos A. , Lopez‐Martin Antonio J. 
Published: May 2014

SummaryA novel Gm‐C filter design technique is presented. It is based on floating‐gate metal oxide semiconductor (FGMOS) transistors and consists in a topological rearrangement of conventional fully differential Gm‐C structures without modifying the employed transconductors at transistor level. The proposed method allows decreasing the number of active elements (transconductors) of the filter. Moreover, high linearity is obtained at low and medium frequencies of the pass band. Drawbacks inherent to the use of FGMOS transistors are analyzed, such as large occupied area, high sensitivity to mismatch, or parasitic zeros in transfer functions. The features of the proposed technique are fully exploited in all‐pole Gm‐C filter design, specially implementing unity gain Butterworth transfer functions. Thus, two low‐power second‐order Butterworth Gm‐C filters have been designed and fabricated to compare the proposed FGMOS technique with their equivalent topologies obtained by a conventional design method. Measurement results for a test chip prototype in a 0.5‐µm standard complementary MOS process are presented, confirming the advantages of the proposed FGMOS design technique. Copyright © 2014 John Wiley & Sons, Ltd.
Analysis of spectrally efficient two‐way relay assisted free space optical systems in atmospheric turbulence with path loss
Authors: Puri Parul , Garg Parul , Aggarwal Mona 
Published: May 2014

SummaryIn this paper, we investigate the performance of two‐way relay assisted free space optical systems over atmospheric turbulence‐induced fading channels affected by molecular absorbtion‐induced path losses. A three node, dual‐hop, bi‐directional, half‐duplex relaying system with independent but not necessarily identically distributed channels is considered. Spectral efficiency is achieved by employing network coding to complete data transmission in two‐time phases. Closed form expression for system outage performance is derived considering decode‐and‐forward protocol. Additionally, the error performance in terms of average symbol error rate for M‐ary phase shift keying is evaluated. Further, the net achievable capacity of the system is also calculated. Copyright © 2014 John Wiley & Sons, Ltd.