bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization and Modeling of the Photocatalytic Degradation of the Insect Repellent DEET in Aqueous TiO2 Suspensions
Authors: Antonopoulou Maria , Konstantinou Ioannis
Published: December 2012

Response surface methodology (RSM) and artificial neural networks (ANNs) based on a multivariate central composite design (CCD) were applied to model and optimize the photocatalytic degradation of N,N‐diethyl‐m‐toluamide (DEET). The individual and interaction effects of three main operating factors (mass of TiO2, initial DEET concentration, and irradiation intensity) on process efficiency were estimated, proving their important effect on % DEET removal. Among the independent variables, TiO2 concentration displayed the highest effect on DEET degradation followed by initial DEET concentration and UV intensity. The optimization and prediction capabilities of ANNs and RSM were compared on the basis of root mean squared error, mean absolute error, absolute average deviation, and correlation coefficient values. Results proved the usefulness and capability of the experimental design strategy for successful investigation and modeling of the photocatalytic process. Moreover, the selected ANN gave better estimation capabilities throughout the range of variables than RSM. Based on the models and the related experimental conditions, the optimal values of each parameter were determined. Under optimum conditions, DEET and total organic carbon (TOC) followed pseudo‐first order kinetics. Nearly complete degradation of DEET took place within 15 min whereas high TOC removal percentages (>85%) was achieved after 90 min irradiation time.
Developing a Collection of Immobilized Nucleoside Phosphorylases for the Preparation of Nucleoside Analogues: Enzymatic Synthesis of Arabinosyladenine and 2′,3′‐Dideoxyinosine
Authors: Serra Immacolata , Ubiali Daniela , Piškur Jure , Christoffersen Stig , Lewkowicz Elizabeth S. , Iribarren Adolfo M. , Albertini Alessandra M. , Terreni Marco
Published: December 2012

The use of nucleoside phosphorylases (NPs; EC 2.4.2.n) represents a convenient alternative to the chemical route for the synthesis of natural and modified nucleosides. We purified four recombinantly expressed nucleoside phosphorylases from the bacterial pathogens Citrobacter koseri, Clostridium perfringens, and Streptococcus pyogenes (CkPNPI, CkPNPII, CpUP, SpUP) and their substrate specificity was investigated towards either natural pyrimidine or purine nucleosides and some analogues, namely, arabinosyladenine (araA) and 2′,3′‐dideoxyinosine (ddI). A 2–3 % activity towards these latter compounds (compared to the natural substrates) was observed. Enzyme activities were compared to the specificities obtained for the enzymes pyrimidine nucleoside phosphorylase from Bacillus subtilis (BsPyNP) and purine nucleoside phosphorylase from Aeromonas hydrophila (AhPNPII) previously reported by some of the authors. The enzymes displaying the suitable specificity for the synthesis of araA and ddI were immobilized on aldehyde–agarose. The immobilized preparations were highly stable at alkaline pH and in the presence of methanol or acetonitrile as cosolvent. They were used in the synthesis of araA and ddI by a one‐pot, bienzymatic transglycosylation achieving 74 and 44 % conversion, respectively.
Effectiveness of topical anesthetics on reducing tactile sensitivity in the paws of newborn rats
Authors: Strain Misty M. , Vineyard Mary Ann , Roberto Megan E. , Brumley Michele R.
Published: December 2012

The aim of this study was to evaluate the effectiveness of three local, topical anesthetics on touch response thresholds of the paws of 1‐day‐old rats. Touch response thresholds were measured using Semmes Weinstein monofilaments after treatment of the paws with EMLA (2.5% lidocaine and 2.5% prilocaine), alcaine (.5% proparacaine), triocaine (20% benzocaine, 6% lidocaine, and 4% tetracaine), or petroleum jelly (treatment control). Touch thresholds significantly increased after treatment with EMLA 18% of the time, and there was no evidence of a systemic effect. Touch thresholds were not significantly altered after treatment with alcaine, triocaine, or petroleum jelly. Therefore, EMLA appears to be a slightly effective topical anesthetic for reducing tactile sensitivity in newborn rats. © 2012 Wiley Periodicals, Inc. Dev Psychobiol 56: 126–132, 2014.
Secretive food concocting in binge eating: Test of a famine hypothesis
Authors: Boggiano Mary M. , Turan Bulent , Maldonado Christine R. , Oswald Kimberly D. , Shuman Ellen S.
Published: December 2012

Objective:

Food concocting, or making strange food mixtures, is well documented in the famine and experimental semistarvation literature and appears anecdotally in rare descriptions of eating disorder (ED) patients but has never been scientifically investigated. Here we do so in the context of binge‐eating using a “famine hypothesis of concocting.”

Method:

A sample of 552 adults varying in binge eating and dieting traits completed a Concocting Survey created for this study. Exploratory ED groups were created to obtain predictions as to the nature of concocting in clinical populations.

Results:

Binge eating predicted the 24.6% of participants who reported having ever concocted but dietary restraint, independently, even after controlling for binge eating, predicted its frequency and salience. Craving was the main motive. Emotions while concocting mirrored classic high‐arousal symptoms associated with drug use; while eating the concoctions were associated with intensely negative/self‐deprecating emotions. Concocting prevalence and salience was greater in the anorexia > bulimia > BED > no ED groups, consistent with their respectively incrementing dieting scores.

Discussion:

Concocting distinguishes binge eating from other overeating and, consistent with the famine hypothesis, is accounted for by dietary restraint. Unlike its adaptive function in famine, concocting could worsen binge‐eating disorders by increasing negative effect, shame, and secrecy. Its assessment in these disorders may prove therapeutically valuable. © 2012 by Wiley Periodicals, Inc. (Int J Eat Disord 2013)
Differential compartmentalization of memory B cells versus plasma cells in salmonid fish
Authors: Ma Cuiyan , Ye Jianmin , Kaattari Stephen L.
Published: December 2012

The disposition of teleost memory and plasma cells (PCs) has essentially been un‐explored. As the organization of the teleost immune system differs significantly from that of mammals (i.e. no bone marrow or lymph nodes, hematopoietic anterior kidney), this disposition could be essential in understanding how comparable functions are achieved. To address this question, the primary and secondary antibody‐secreting cell, B memory cell, and antibody responses to T‐independent and T‐dependent antigens were analyzed in trout. Although the TI and TD antibody responses did not differ substantively from one another, the secondary responses to both were significantly prolonged compared with the primary responses. Logarithmic increases in titer and affinity were achieved for both antigens during the primary, with only modest increases during the secondary response. Antibody‐secreting cells, both PCs and plasmablasts, quantitatively paralleled antibody production, with antibody‐secreting cells skewing to the hematopoietic anterior kidney for both antigens. However, the enhanced antigen‐inducible response of immune fish (indicative of the memory pool) skewed to the peripheral blood and spleen. This pattern of memory versus PC disposition parallels that observed in mammals even though the organization of the respective immune systems differs considerably.
Tc9 cells, a new subset of CD8+ T cells, support Th2‐mediated airway inflammation
Authors: Visekruna Alexander , Ritter Josephine , Scholz Tatjana , Campos Lucia , Guralnik Anna , Poncette Lucia , Raifer Hartmann , Hagner Stefanie , Garn Holger , Staudt Valerie , Bopp Tobias , Reuter Sebastian , Taube Christian , Loser Karin , Huber Magdalena
Published: December 2012

Similar to T‐helper (Th) cells, CD8+ T cells also differentiate into distinct subpopulations. However, the existence of IL‐9‐producing CD8+ T (Tc9) cells has not been elucidated so far. We show that murine CD8+ T cells activated in the presence of IL‐4 plus TGF‐β develop into transient IL‐9 producers characterized by specific IFN‐γ and IL‐10 expression patterns as well as by low cytotoxic function along with diminished expression of the CTL‐associated transcription factors T‐bet and Eomesodermin. Similarly to the CD4+ counterpart, Tc9 cells required for their differentiation STAT6 and IRF4. Tc9 cells deficient for these master regulators displayed increased levels of Foxp3 that in turn suppressed IL‐9 production. In an allergic airway disease model, Tc9 cells promoted the onset of airway inflammation, mediated by subpathogenic numbers of Th2 cells. This support was specific for Tc9 cells because CTLs failed to exert this function. We detected increased Tc9 frequency in the periphery in mice and humans with atopic dermatitis, a Th2‐associated skin disease that often precedes asthma. Thus, our data point to the existence of Tc9 cells and to their supportive function in Th2‐dependent airway inflammation, suggesting that these cells might be a therapeutic target in allergic disorders.
Loss of methylation at the IFNG promoter and CNS‐1 is associated with the development of functional IFN‐γ memory in human CD4+T lymphocytes
Authors: Dong Jun , Chang Hyun‐Dong , Ivascu Claudia , Qian Yu , Rezai Soheila , Okhrimenko Anna , Cosmi Lorenzo , Maggi Laura , Eckhardt Florian , Wu Peihua , Sieper Joachim , Alexander Tobias , Annunziato Francesco , Gossen Manfred , Li Jun , Radbruch Andreas , Thiel Andreas
Published: December 2012

Cytokine memory for IFN‐γ production by effector/memory Th1 cells plays a key role in both protective and pathological immune responses. To understand the epigenetic mechanism determining the ontogeny of effector/memory Th1 cells characterized by stable effector functions, we identified a T‐cell‐specific methylation pattern at the IFNG promoter and CNS‐1 in ex vivo effector/memory Th1 cells, and investigated methylation dynamics of these regions during the development of effector/memory Th1 cells. During Th1 differentiation, demethylation occurred at both the promoter and CNS‐1 regions of IFNG as early as 16 h, and this process was independent of cell proliferation and DNA synthesis. Using an IFN‐γ capture assay, we found early IFN‐γ‐producing cells from 2‐day differentiating cultures acquired “permissive” levels of demethylation and developed into effector/memory Th1 cells undergoing progressive demethylation at the IFNG promoter and CNS‐1 when induced by IL‐12. Methylation levels of these regions in effector/memory Th1 cells of peripheral blood from rheumatoid arthritis patients correlated inversely with reduced frequencies of IFN‐γ‐producers, coincident with recruitment of effector/memory Th1 cells to the site of inflammation. Thus, after termination of TCR stimulation, IL‐12 signaling potentiates the stable functional IFN‐γ memory in effector/memory Th1 cells characterized by hypomethylation at the IFNG promoter and CNS‐1.
2D Bimetallic Oxalate‐Based Ferromagnets with Inserted [Fe(4‐Br‐sal2‐trien)]+ and [Fe(3‐R‐sal2‐trien)]+ (R = Br, Cl and CH3O) FeIII Spin‐Crossover Complexes
Authors: Clemente‐León Miguel , Coronado Eugenio , López‐Jordà Maurici
Published: December 2012

The syntheses, structures and magnetic properties of the compounds of formula [FeIII(4‐Br‐sal2‐trien)][MnIICrIII(ox)3]0.67Cl0.33·CH3OH_solvate (1), [FeIII(3‐Br‐sal2‐trien)][MnIICrIII(ox)3]·(CH3CN)2 (2), [FeIII(3‐Cl‐sal2‐trien)][MnIICrIII(ox)3]·(CH3OH)2·(CH3CN)2 (3) and [FeIII(3‐CH3O‐sal2‐trien)][MnIICrIII(ox)3]·(CH3OH)·(H2O)1.5·(CH2Cl2)0.5 (4) are reported. The four structures present a 2D honeycomb anionic layer formed by MnII and CrIII ions linked through oxalate ligands and a cationic layer of the FeIII complexes intercalated between the 2D oxalate network. The main differences compared with previous 2D oxalate‐based structures are the presence of double layers of cations in compounds 1, 3 and 4 and porous channels in the structures of 1 and 4 filled with disordered solvent molecules. The magnetic properties indicate that the inserted FeIII cations undergo an almost complete spin crossover above 300 K in 1 and a partial spin crossover in 3 and 4 that coexists with a ferromagnetic ordering of the oxalate network. In the case of 2, the inserted cation remains in the HS from 2 to 300 K. Therefore, 1, 3 and 4 are multifunctional compounds with coexistence of spin crossover and magnetic ordering. Conversely, photomagnetic characterization shows that 1 and 3 do not present a LIESST effect in contrast to the 2D compound [FeIII(sal2‐trien)][MnIICrIII(ox)3]·(CH2Cl2). These results could help to clarify this rare property for a FeIII complex.
A Hexanuclear Cobalt(II) Cluster Incorporated in a Banana‐Shaped Tungstovanadate: [(Co(OH2)Co2VW9O34)2(VW6O26)]17–
Authors: Lv Hongjin , Song Jie , Geletii Yurii V. , Guo Weiwei , Bacsa John , Hill Craig L.
Published: December 2012

The hexanuclear cobalt‐containing tungstovanadate complex, Na17[(Co(OH2)Co2VW9O34)2(VW6O26)]·31H2O (1) has been synthesized through reaction of cobalt nitrate, sodium tungstate, and V2O5 in acetate buffer solution. The title compound has been characterized by X‐ray crystallography, elemental analysis, FTIR, UV/Vis, and 51V NMR spectroscopy and by cyclic voltammetry. Complex 1 crystallizes in the monoclinic space group P21/c (a = 15.706(3) Å, b = 21.973(5) Å, c = 35.080(8) Å, α = 90°, β = 97.420(3)°, γ = 90°; V = 12005(5) Å3; Z = 4; based on 192337 independent reflections), which consists of two tri‐CoII substituted B‐α‐[(Co(OH2)Co2VW9O39)] Keggin units bridged by one unique [VW6O16] fragment leading to a banana‐shaped structure with idealized C2ν symmetry. Stability studies show that polyoxoanion 1 ultimately transforms into the tetracobalt‐containing sandwich‐type polyoxoanion, 2, as confirmed by 51V NMR and X‐ray crystallographic analyses. Polyoxoanion 1 shows catalytic activity for the H2O2‐based epoxidation of 1‐hexene and cyclohexene in 1,2‐dichloroethane solvent.
Iridium and Rhodium Complexes with the Hemilabile Ligand [2‐(1,3‐Dioxolane‐2‐yl)phenyl]diphenylphosphane – Behaviour in Solution and Structural Characterization
Authors: Barquín Montserrat , Ciganda Roberto , Garralda María A. , Ibarlucea Lourdes , Mendicute‐Fierro Claudio , Rodríguez‐Diéguez Antonio , Seco José M.
Published: December 2012

[MCl(L2)]2 (M = Ir, L2 = 1,5‐cyclooctadiene; M = Rh, L2 = norbornadiene) reacts with [2‐(1,3‐dioxolane‐2‐yl)phenyl]diphenylphosphane (1) to afford [MCl(L2)(P~O)] (M = Ir, 2; M = Rh, 3), in which the ligand is P‐monodentate. Complex 3 reacts with AgClO4 to give [Rh(Nbd)(PO)]ClO4 (4), in which the ligand is P,O‐bidentate. Complex 2 is static at room temp., whereas 3 and 4 undergo intramolecular exchanges, which are fast at room temperature and slow at 223 K. The conformational changes in 4 are still fast at 223 K. Complexes 2–4 react with CO to afford trans‐[MCl(CO)(P~O)2] (M = Ir, 5; M = Rh, 6) or trans‐[Rh(CO)2(P~O)2]ClO4 (7). Cyclooctadiene complexes react with PPh2(o‐C6H4CHO) to afford [MClH(PPh2(o‐C6H4CO))(PO] (M = Ir, 8; M = Rh, 9), in which 1 is chelating. Complex 8 contains a single diastereomer, is static in the 303–213 K range and reacts with CO to form [IrClH(PPh2(o‐C6H4CO))(P~O)(CO)] (10). Complex 9 contains two diastereomers 9a/9b in a 95:5 ratio that undergo interconversion, which is slow at low temperature, and reacts with CO to undergo reductive elimination of aldehyde, cleavage of the Rh–O bond and scrambling of phosphanes. A mixture of trans‐[RhCl(CO)(κ1‐PPh2(o‐C6H4CHO))(P~O)] (11), 6 and trans‐[RhCl(CO)(κ1‐PPh2(o‐C6H4CHO))2] is formed. Bubbling of nitrogen transforms 11 back into 9. Compound 2 reacts with hydrogen to give the fluxional [IrCl(H)2(P~O)(PO)] (12) with trans P atoms and cis H atoms, which attains coalescence at 203 K. Complex 12 reacts with mono‐ or bidentate ligands to afford static [IrCl(H)2(P~O)2L] (L = CO, 13; py, 14; nPrNH2, 15) or [Ir(H)2(P~O)2(en)]BPh4 (16, en = ethylenediamine). Abstraction of halide from 12 affords [Ir(H)2(PO)2]BPh4 (17), which is fluxional owing to interconversion between only two of the possible four diastereomers, for which ΔH‡ = 54.7 ± 0.7 kJ mol–1 and ΔS‡ = 4.7 ± 0.2 J K–1 mol–1. The X‐ray structures of 8, 15 and 16 are also reported.
Synthesis and Structure of Seven‐Membered Metallacycloalkynes
Authors: Suzuki Noriyuki , Tsuchiya Takashi , Aihara Naoto , Iwasaki Masakazu , Saburi Masahiko , Chihara Teiji , Masuyama Yoshiro
Published: December 2012

Seven‐membered metallacycloalkyne compounds were synthesized. The reaction of the zirconocene–ethylene complex and (Z)‐1,4‐bis(trimethylsilyl)buta‐1,2,3‐triene gave a mixture of 1‐zirconacyclopent‐3‐yne and 1‐zirconacyclohept‐3‐yne. In contrast, zirconocene–alkyne complexes, such as those of 1‐(trimethylsilyl)prop‐1‐yne and diphenylacetylene, gave 1‐zirconacyclohept‐2‐en‐5‐yne in good yields. Consideration of structural parameters suggests that both a seven‐membered cyclic alkyne and a five‐membered structure contribute to generation of this complex. Coupling of benzyne and [3]cumulenes on a metal was also found to afford the corresponding metallacycles.
Synthesis and Characterization of [Mo3S4(NDABu)(HNDABu)2]3– and [Mo3S4(HNDAPr)3]2– Anions as Building Blocks for Organic–Inorganic Hybrid Solids
Authors: Duval Sylvain , Dumur Frédéric , Guénée Laure , Marrot Jérôme , Simonnet‐Jégat Corine , Cadot Emmanuel
Published: December 2012

The polymetallic cation [Mo3S4(H2O)9]4+ was used as an inorganic precursor to generate new hybrid organic–inorganic chalcogenide clusters. Three organic compounds with flexible and hanging arms were synthesized and investigated as ligands for coordination complexes with the rigid and electroactive inorganic {Mo3S4} unit. Interestingly, the {Mo3S4} core formed hybrid structures with the flexible H3NDABu [N‐(3‐carboxypropyl)iminodiacetic acid] and H3NDAPr [N‐(2‐carboxyethyl)iminodiacetic acid] ligands, which were characterized by X‐ray crystallography. Surprisingly, no crystals were isolated, when the more rigid H3NDABn [N‐(4‐methoxycarbonylbenzyl)iminodiacetic acid] ligand was used. The two coordination complexes [Mo3S4(NDABu)(HNDABu)2]3– and [Mo3S4(HNDAPr)3]2– were characterized by X‐ray diffraction (XRD), IR spectroscopy, thermal gravimetric analysis (TGA), 1H NMR spectroscopy, elemental analysis, and electrochemistry. The organic ligands H3NDABu, H3NDAPr, and H3NDABn were characterized by XRD, IR, HR mass, and 13C and 1H NMR spectroscopy. [Mo3S4(NDABu)(HNDABu)2]3– and [Mo3S4(HNDAPr)3]2– constitute promising preformed building blocks to generate new organic–inorganic hybrid molecular or extended materials.
One‐Pot Synthesis of Alkyl Styryl Sulfides Free from Transition Metal/Ligand Catalyst and Thiols
Authors: Heredia Adrián A. , Peñéñory Alicia B.
Published: December 2012

A new protocol for the one‐pot synthesis of styryl alkyl sulfides was developed. This methodology involves the in situ generation of thiolate anions by nucleophilic substitution between potassium thioacetate and alkyl halides followed by fragmentation. Further reactions of these thiolate anions with substituted (E,Z)‐β‐styryl halides gave the corresponding sulfides with retention of stereochemistry in good to excellent yields. This procedure does not require a metal catalyst, it proceeds under mild conditions and in short times, and it is free from malodorous and air‐sensitive alkyl thiols.
Asymmetric Organocatalytic 1,4‐Addition Reactions Starting from Enals with gem‐Difluoroalkyl Side Chains
Authors: Khalaf Ali , Grée Danielle , Abdallah Hassan , Jaber Nada , Hachem Ali , Grée René
Published: December 2012

gem‐Difluoroenals are excellent substrates for asymmetric organocatalytic 1,4‐additions of thiols and anilines. By using diarylsilylprolinol ether as a catalyst, good to excellent yields with ee values in the same range (up to 98 %) were obtained. The CF2R group strongly activates the enals towards these organocatalytic additions.
The apparent hydrodynamic slip of polymer solutions and its implications in electrokinetics
Authors: Berli Claudio L. A.
Published: December 2012

The apparent hydrodynamic slip of polymer solutions is a result of polymer depletion at channel walls, and its fluid dynamic effects are well known. This work reviews the evidences of apparent slip in electrokinetics, and discusses practical consequences in the following fields: (i) electrokinetic transport of polymer solutions in microchannels, which is of interest for the design and operation of microfluidic chips, particularly for electrophoresis; (ii) electroosmotic pumping, where it has been observed that the employment of polymer solutions greatly enhances the output pressure; and (iii) electrokinetic energy conversion, where the apparent slip also contributes to improve the conversion efficiency. In all cases, critical discussions are taken from basic physical concepts.
Cardiomyocyte proliferation and progenitor cell recruitment underlie therapeutic regeneration after myocardial infarction in the adult mouse heart
Authors: Malliaras Konstantinos , Zhang Yiqiang , Seinfeld Jeffrey , Galang Giselle , Tseliou Eleni , Cheng Ke , Sun Baiming , Aminzadeh Mohammad , Marbán Eduardo
Published: December 2012

Cardiosphere‐derived cells (CDCs) have been shown to regenerate infarcted myocardium in patients after myocardial infarction (MI). However, whether the cells of the newly formed myocardium originate from the proliferation of adult cardiomyocytes or from the differentiation of endogenous stem cells remains unknown. Using genetic fate mapping to mark resident myocytes in combination with long‐term BrdU pulsing, we investigated the origins of postnatal cardiomyogenesis in the normal, infarcted and cell‐treated adult mammalian heart. In the normal mouse heart, cardiomyocyte turnover occurs predominantly through proliferation of resident cardiomyocytes at a rate of ∼1.3–4%/year. After MI, new cardiomyocytes arise from both progenitors as well as pre‐existing cardiomyocytes. Transplantation of CDCs upregulates host cardiomyocyte cycling and recruitment of endogenous progenitors, while boosting heart function and increasing viable myocardium. The observed phenomena cannot be explained by cardiomyocyte polyploidization, bi/multinucleation, cell fusion or DNA repair. Thus, CDCs induce myocardial regeneration by differentially upregulating two mechanisms of endogenous cell proliferation.

→See accompanying article http://dx.doi.org/10.1002/emmm.201202345
Spliceosome integrity is defective in the motor neuron diseases ALS and SMA
Authors: Tsuiji Hitomi , Iguchi Yohei , Furuya Asako , Kataoka Ayane , Hatsuta Hiroyuki , Atsuta Naoki , Tanaka Fumiaki , Hashizume Yoshio , Akatsu Hiroyasu , Murayama Shigeo , Sobue Gen , Yamanaka Koji
Published: December 2012

Two motor neuron diseases, amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA), are caused by distinct genes involved in RNA metabolism, TDP‐43 and FUS/TLS, and SMN, respectively. However, whether there is a shared defective mechanism in RNA metabolism common to these two diseases remains unclear. Here, we show that TDP‐43 and FUS/TLS localize in nuclear Gems through an association with SMN, and that all three proteins function in spliceosome maintenance. We also show that in ALS, Gems are lost, U snRNA levels are up‐regulated and spliceosomal U snRNPs abnormally and extensively accumulate in motor neuron nuclei, but not in the temporal lobe of FTLD with TDP‐43 pathology. This aberrant accumulation of U snRNAs in ALS motor neurons is in direct contrast to SMA motor neurons, which show reduced amounts of U snRNAs, while both have defects in the spliceosome. These findings indicate that a profound loss of spliceosome integrity is a critical mechanism common to neurodegeneration in ALS and SMA, and may explain cell‐type specific vulnerability of motor neurons.
ZrC–C and ZrO2–C as Novel Supports of Pd Catalysts for Formic Acid Electrooxidation
Authors: Qu W.‐L. , Wang Z.‐B. , Sui X.‐L. , Gu D.‐M. , Yin G.‐P.
Published: December 2012

The Pd/ZrC–C and Pd/ZrO2–C catalysts with zirconium compounds ZrC or ZrO2 and carbon hybrids as novel supports for direct formic acid fuel cell (DFAFC) have been synthesized by microwave‐assisted polyol process. The Pd/ZrC–C and Pd/ZrO2–C catalysts have been characterized by X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), energy dispersive analysis of X‐ray (EDAX), transmission electron microscopy (TEM), and electrochemical measurements. The physical characteristics present that the zirconium compounds ZrC and ZrO2 may promote the dispersion of Pd nanoparticles. The results of electrochemical tests show that the activity and stability of Pd/ZrC–C and Pd/ZrO2–C catalysts show higher than that of Pd/C catalyst for formic acid electrooxidation due to anti‐corrosion property of zirconium compounds ZrC, ZrO2, and metal–support interaction between Pd nanoparticles and ZrC, ZrO2. The Pd/ZrC–C catalyst displays the best performance among the three catalysts. The peak current density of formic acid electrooxidation on Pd/ZrC–C electrode is nearly 1.63 times of that on Pd/C. The optimal mass ratio of ZrC to XC‐72 carbon is 1:1 in Pd/ZrC–C catalyst with narrower particle size distribution and better dispersion on surface of the mixture support, which exhibits the best activity and stability for formic acid electrooxidation among all the samples.
Coordination of Ligands That Contain Thiocarbonyl, Carbonyl, or Thiolate Functionalities to Complex Fragments of Palladium in Various Oxidation States
Authors: Dobrzańska Liliana , Stander‐Grobler Elzet , Strasser Christoph E. , Cronje Stephanie , Raubenheimer Helgard G.
Published: December 2012

Two phosphine ligands of [Pd(PPh3)4] were substituted by π(CS) coordination of 4‐bromodithiobenzoic acid methyl ester resulting in complex 1. The same ester, after alkylation, afforded the dicationic complex bis(μ‐methanethiolato)tetrakis(triphenylphosphine)dipalladium(2+) bis(tetrafluoroborate) (2) from the same palladium source. A related thiolato‐bridged complex, bis(μ‐methanethiolato)bis(1‐methylpyridin‐2(1H)‐ylidene)bis(triphenylphosphine)dipalladium(2+) bis(tetrafluoroborate) (4) and the trinuclear cluster tris(μ‐methanethiolato)tris(triphenylphosphine)tripalladium(+)(3PdPd) (5) resulted from treatment of a known cationic pyridinylidene complex with MeSLi. The double oxidative substitution reaction of [Pd(PPh3)4] with 1,5‐dichloro‐9,10‐anthraquinone afforded trans‐dichloro[μ‐(9,10‐dihydro‐9,10‐dioxoanthracene‐1,5‐diyl)]tetrakis(triphenylphosphine)dipalladium (6). Some of these complexes could be fully characterized by 1H‐, 13C‐, and 31P‐NMR spectroscopy, mass spectrometry, and elemental analysis. The crystal and molecular structures of all of them, and of trans‐bis(1,3‐dihydro‐1,3‐dimethyl‐2H‐imidazol‐2‐ylidene)diiodopalladium (3), were determined by single‐crystal X‐ray diffraction.
Ab initio MO Theory – An Important Tool in Foldamer Research: Prediction of Helices in Oligomers of ω‐Amino Acids
Authors: Baldauf Carsten , Hofmann Hans‐Jörg
Published: December 2012

The enormous developments of computer technologies allow the broad employment of ab initio MO theory in foldamer research. In this review, we demonstrate the efficiency and reliability of ab initio MO methods for the description of the helix formation in oligomers of ω‐amino acids on the basis of representative examples. Thus, ab initio MO theory successfully accompanies foldamer research by confirmation and interpretation of experimental results and stimulation of future experiments. The high predictive power of the methods opens the way to novel structure classes with special properties. Nowadays, ab initio MO theory has become an inherent part in the arsenal of methods applied in foldamer research.
Fluorine in Peptides: The Synthesis of α‐Fluoro‐β‐Amino Dipeptides by Direct Deoxofluorination/Rearrangement of N‐Seryl Dipeptides
Authors: Smith Daniel L. , Slawin Alexandra M. Z. , O'Hagan David
Published: December 2012

This article describes the stereo‐ and regioselectivity of the deoxofluorination of N‐terminal dipeptides bearing a serine residue to generate, after rearrangement, α‐fluoro‐β‐amine‐terminated dipeptides. The ratio of the rearranged α‐fluorinated regioisomer is increased, relative to the non‐rearranged β‐fluoro isomer, with N‐alkylated amides. Otherwise, an intramolecular H‐bond between the free amine and the amide NH suppresses formation of the key aziridinium intermediate required for α‐fluorination. N‐Methyl and N‐allyl amides give exclusively α‐fluorination products. Subsequent deprotection of the N‐allyl amide to give a α‐fluoro‐β‐amino dipeptide product is demonstrated.
Main‐Chain Scission of a Charged Fifth‐Generation Dendronized Polymer
Authors: Yu Hao , Schlüter A. Dieter , Zhang Baozhong
Published: December 2012

During divergent synthesis of the next higher‐generation dendronized polymer (DP), the fifth‐generation DP, PG5, with a number‐average degree of polymerization, (i.e., number of monomeric units) Pn, of ca. 500 underwent main‐chain scission. This happened in the step when its peripheral Boc groups were removed by the treatment with trifluoroacetic acid (TFA), and thus a heavily charged polyelectrolyte formed as an intermediate. Atomic Force Mircoscopy (AFM) analysis of the product after drop‐casting onto mica showed a large majority of short deprotected PG5 chains with Pn of ca. 40, as well as some smaller features that by MALDI‐TOF mass spectrometry and 1H‐NMR spectroscopy were assigned to the hypothetical monomer, deprotected MG5. This behavior is compared to a recently reported main‐chain scission of a closely related PG5 which, however, resulted in significantly longer fragments. While this difference cannot yet be fully explained, questions are formulated which will guide future research.
2,3,10,11‐Tetrahydroxytetraphenylene and Its Application in Molecular Recognition
Authors: Cui Jian‐Fang , Chen Chao , Gao Xiang , Cai Zong‐Wei , Han Jian‐Wei , Wong Henry N. C.
Published: December 2012

A rationally designed 2,3,10,11‐tetrahydroxytetraphenylene (1) has been synthesized. Employing 1 as a building block, a structurally novel tweezer‐like host 2 containing dibenzo‐24‐crown‐8 moieties has been prepared. Host 2 showed excellent molecular‐recognition ability toward paraquat (=1,1′‐dimethyl‐4,4′‐bipyridinium dichloride) derivative 3a to form a 1 : 1 stable complex in solution.
A Capture‐and‐Release Catalytic Flow System
Authors: Suzuki Yoshikazu , Laurino Paola , McQuade D. Tyler , Seeberger Peter H.
Published: December 2012

Supported transition‐metal catalysts offer the promise of catalyst reuse in order to make chemical transformations more environmentally friendly and less expensive; however, catalysts that are supported on insoluble scaffolds often exhibit significantly reduced selectivities and rates. A capture/release strategy that unites the benefits of heterogeneous and homogeneous catalysis would overcome these current shortcomings. Herein, we report on a novel capture‐and‐release flow system that takes advantage of a non‐covalent pyrenesingle wall nanotube (SWNT) interaction. We demonstrate that a Pd complex containing one or two pyrene arms is captured and released from a SWNT column at different rates and can be utilized for the homogeneous catalysis of Suzuki and Heck reactions.
Carboboration Reactions of 1,2‐Bis[(diarylphosphino)ethynyl]benzenes with Tris(pentafluorophenyl)borane
Authors: Liedtke René , Kehr Gerald , Fröhlich Roland , Daniliuc Constantin G. , Wibbeling Birgit , Petersen Jeffrey L. , Erker Gerhard
Published: December 2012

The 1,2‐bis[(diarylphosphino)ethynyl]benzene derivatives 1a (R=Ph) and 1b (R=o‐tolyl) undergo 1,1‐carboboration at one of their acetylene units upon treatment with (C6F5)3B at elevated temperature to give the products 5a and 5b, respectively. At room temperature, we observed the formation of the corresponding phosphireniumborate zwitterions, 7a and 7b, respectively, which may be intermediates of the 1,1‐carboboration reactions. The reaction of the more bulky 1,2‐bis[(dimesitylphosphino)ethynyl]benzene 1c with (C6F5)3B takes a different course. At 110°, we observed the complete conversion to the benzopentafulvene derivative 8 which is probably formed in a typical carbocation rearrangement sequence after the initial (C6F5)3B Lewis acid‐addition step. The compounds 5a, 5b, 7b, and 8 were characterized by X‐ray crystal‐structure analyses.
Organocatalysis of CN/CN and CC/CN Exchange in Dynamic Covalent Chemistry
Authors: Wilhelms Nadine , Kulchat Sirinan , Lehn Jean‐Marie
Published: December 2012

The reversibly formed CN bond plays a very important role in dynamic covalent chemistry and the CN/CN exchange of components between different imine constituents to create dynamic covalent libraries has been extensively used. To facilitate diversity generation, we have investigated an organocatalyzed approach, using L‐proline as catalyst, to accelerate the formation of dynamic libraries of [n×n] imine components. The organocatalysis methodology has also been extended, under somewhat modified conditions, to reversible CC/CN exchange processes between Knoevenagel derivatives of barbituric acid and imines, allowing for the generation of increased diversity.
The Structural Characterization of Folded Peptides Containing the Conformationally Constrained β‐Amino Acid Residue β2,2Ac6c
Authors: Basuroy Krishnayan , Karuppiah Vasantham , Shamala Narayanaswamy , Balaram Padmanabhan
Published: December 2012

Backbone alkylation has been shown to result in a dramatic reduction in the conformational space that is sterically accessible to α‐amino acid residues in peptides. By extension, the presence of geminal dialkyl substituents at backbone atoms also restricts available conformational space for β and γ residues. Five peptides containing the achiral β2,2‐disubstituted β‐amino acid residue, 1‐(aminomethyl)cyclohexanecarboxylic acid (β2,2Ac6c), have been structurally characterized in crystals by X‐ray diffraction. The tripeptide Boc‐Aib‐β2,2Ac6c‐Aib‐OMe (1) adopts a novel fold stabilized by two intramolecular H‐bonds (C11 and C9) of opposite directionality. The tetrapeptide Boc‐[Aib‐β2,2Ac6c]2‐OMe (2) and pentapeptide Boc‐[Aib‐β2,2Ac6c]2‐Aib‐OMe (3) form short stretches of a hybrid αβ C11 helix stabilized by two and three intramolecular H‐bonds, respectively. The structure of the dipeptide Boc‐Aib‐β2,2Ac6c‐OMe (5) does not reveal any intramolecular H‐bond. The aggregation pattern in the crystal provides an example of an extended conformation of the β2,2Ac6c residue, forming a ‘polar sheet’ like H‐bond. The protected derivative Ac‐β2,2Ac6c‐NHMe (4) adopts a locally folded gauche conformation about the CβCα bonds (θ=−55.7°). Of the seven examples of β2,2Ac6c residues reported here, six adopt gauche conformations, a feature which promotes local folding when incorporated into peptides. A comparison between the conformational properties of β2,2Ac6c and β3,3Ac6c residues, in peptides, is presented. Backbone torsional parameters of H‐bonded αβ/βα turns are derived from the structures presented in this study and earlier reports.
The Effects of Scenario Planning on Participant Perceptions of Learning Organization Characteristics
Authors: Haeffner Melissa , Leone Deanna , Coons Laura , Chermack Thomas
Published: December 2012

Scenario planning is often used by organizations to think about future uncertainties. However, what it does in terms of changing perceptions is difficult to assess and quantify. To address this need, this article builds on previous studies documenting the effectiveness of scenario planning. Specifically, this article contributes to the data on perceptions of learning organization characteristics. This study compiles quantitative data gathered from 133 individuals working in 10 United States companies who participated in scenario planning. The Dimensions of the Learning Organization Questionnaire (DLOQ) instrument was used in a pre‐ and post‐test research design and differences were analyzed using a t‐test. Results show a positive relationship between scenario planning and improved perceptions of learning organization characteristics for six of the seven dimensions of the DLOQ. Interpretation of the results suggests that scenario planning can change participants' views of their organizations' adaptive learning characteristics.
Synthesis and characterization of thermoresponsive copolymers for drug delivery
Authors: Aerry Swati , De Arnab , Kumar Ajeet , Saxena Amit , Majumdar D. K. , Mozumdar Subho
Published: December 2012

We report the synthesis and characterization of two nontoxic, thermogelling drug delivery systems which are liquid at room temperatures but become a gel at physiological temperature (37°C) potentially leading to release of a drug molecule. We selected temperature as the stimulus for drug release as it is physiologically invariant. A free radical polymerization of N‐isopropylacrylamide (NIPAM) and N‐vinylpyrrolidone (VP) was carried out under nitrogen atmosphere in double‐distilled water at two different temperatures (30°C and 70°C), and the copolymers obtained were characterized by various analytical techniques. The molar ratios of the two monomers were altered with increasing NIPAM content and their cloud point temperature or least critical solution temperature (LCST) was determined. The copolymer at 9:1 ratio of NIPAM to VP resulted in the formation of nanoparticle‐based gel (NG1) at 30°C; however, at 70°C, a microgel (MG1) was formed. The LCST of the nanogel and microgel was 33.5–34°C and 36.5–37°C, respectively. Thus, both the copolymers are water soluble at room temperature, but distinct phases appear at physiological temperatures. We hypothesized that these copolymers on entrapment with a drug could be used for topical application to the skin or eye for controlled drug delivery applications. Toxicological studies revealed that the copolymers are nontoxic in HeLa cells. Finally, our experiments show that a model drug [bovine serum albumin (BSA)] is released at 37°C with zero‐order kinetics and confirmed using multiple well‐known mathematical models. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
Preparation and properties of tannic acid cross‐linked collagen scaffold and its application in wound healing
Authors: Natarajan Venkatachalam , Krithica Natarajan , Madhan Balaraman , Sehgal Praveen Kumar
Published: December 2012

A biodurable porous scaffold of collagen with good biocompatibility and enhanced wound healing potential is prepared through casting technique using tannic acid (TA) as crosslinker. The morphological analysis of the tannic acid cross‐linked collagen scaffold (TCCs) distinctively shows scaly interlinks with large pores. The enzymatic stability of the scaffold is characterized in vitro to detail the role of TA in stabilization of collagen matrix against collagenolytic degradation. TCCs shows more stability (>54%) against collagenase than that of the collagen scaffolds (Cs). The attenuated total reflectance Fourier transform infrared analysis of the TCCs confirms the noncovalent interaction between collagen and TA. The biocompatibility of the scaffold (TCCs) in vitro has been established using 3T3 fibroblasts. Therapeutic and wound healing potential of the TCCs has been studied in vivo using excision wound model in rats. The results clearly indicates that the TCCs has greater and significant effect in wound closure and increased the wound healing rate compared with native Cs. This biocompatible and biodurable scaffold may find broad applications in the tissue engineering and drug delivery applications. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.
Treatment of melasma with the 1,927‐nm fractional thulium fiber laser: A retrospective analysis of 20 cases with long‐term follow‐up
Authors: Niwa Massaki Ane Beatriz M. , Eimpunth Sasima , Fabi Sabrina G. , Guiha Isabella , Groff William , Fitzpatrick Richard
Published: December 2012

Background

Melasma is a common acquired symmetrical hyperpigmentation that is often recurrent and refractory.

Objectives

To investigate the efficacy and safety of a single administration of high‐density fractional thulium fiber laser (1,927 nm) for the treatment of refractory melasma in 20 patients.

Materials and Methods

A retrospective chart and photographs review of 20 women (Fitzpatrick skin type II–IV) with clinical diagnosis of melasma treated with the 1,927‐nm fractionated thulium laser at 10 or 20 mJ/cm2, with 60–70% surface area coverage. Four investigators independently evaluated Melasma Area Severity Index (MASI) scores before, 4 weeks, 3–6 months, and 6–12 months after treatment.

Results

Mean MASI scores decreased dramatically from 13.2 ± 5.4 before treatment to 8.5 ± 3.5 at 4 weeks after laser treatment (P = 0.004). Patient assessment revealed that 12 of the 20 subjects had more than 50% clearance of their melasma. Recurrence was reported by 7 out of 15 patients who were successfully followed‐up (mean 10.2 months). Two patients developed postinflammatory hyperpigmentation that subsided with topical bleaching after 3 months.

Conclusion

High‐density coverage fractional 1,927‐nm thulium laser proved to be safe and effective for melasma with long‐term remission. Lasers Surg. Med. 45: 95–101, 2013. © 2012 Wiley Periodicals, Inc.
Topical perfluorodecalin resolves immediate whitening reactions and allows rapid effective multiple pass treatment of tattoos
Authors: Reddy Kavitha K. , Brauer Jeremy A. , Anolik Robert , Bernstein Leonard , Brightman Lori , Hale Elizabeth , Karen Julie , Weiss Elliot , Geronemus Roy G.
Published: December 2012

Background and Objective

Laser tattoo removal using multiple passes per session, with each pass delivered after spontaneous resolution of whitening, improves tattoo fading in a 60‐minute treatment time. Our objective was to evaluate the safety and efficacy of topical perfluorodecalin (PFD) in facilitating rapid effective multiple‐pass tattoo removal.

Study Design

In a randomized, controlled study using Q‐switched ruby or Nd:YAG laser, 22 previously treated tattoos were treated with 3 passes using PFD to resolve whitening after each pass (“R0 method”). In previously untreated symmetric tattoos, seven were treated over half of the tattoo with the R20 method, and the opposite half with 4 passes using PFD (R0 method); two were treated over half with a single pass and the opposite half with 4 passes using PFD (R0 method); and six treated over half with a single pass followed by PFD and the opposite half with a single pass alone. Blinded dermatologists rated tattoo fading at 1–3 months. Optical coherence tomography (OCT) imaging of whitening was performed in two tattoos.

Results

Topical PFD clinically resolved immediate whitening reactions within a mean 5 seconds (range 3–10 seconds). Tattoos treated with the R0 method demonstrated excellent fading in an average total treatment time of 5 minutes. Tattoo areas treated with the R0 method demonstrated equal fading compared to the R20 method, and improved fading compared to a single pass method. OCT imaging of whitening demonstrated epidermal and dermal hyper‐reflective “bubbles” that dissipated until absent at 9–10 minutes after PFD application, and at 20 minutes without intervention.

Conclusions

Multiple‐pass tattoo removal using PFD to deliver rapid sequential passes (R0 method) appears equally effective as the R20 method, in a total treatment time averaging 5 minutes, and more effective than single pass treatment. OCT‐visualized whitening‐associated “bubbles,” upon treatment with PFD, resolve twice as rapidly as spontaneous resolution. Lasers Surg. Med. 45: 76–80, 2013. © 2012 Wiley Periodicals, Inc.
PKM2 inhibitor shikonin suppresses TPA‐induced mitochondrial malfunction and proliferation of skin epidermal JB6 cells
Authors: Li Wenjuan , Liu Joan , Zhao Yunfeng
Published: December 2012

Chemoprevention has been a pivotal and effective strategy during the skin cancer treatment. Using human skin normal and tumor samples, we demonstrated that both the expression and activity levels of pyruvate kinase M2 (PKM2) were higher in skin tumor tissues than normal tissues, suggesting that PKM2, one of important metabolic enzyme, might serve as a target for skin cancer prevention and/or therapy. Shikonin, a small‐molecule active chemical, has been studied as an anti‐cancer drug candidate in human cancer models. However, the mechanism of action and the chemopreventive potential of shikonin are unclear. Herein, we used the skin epidermal JB6 P+ cells and demonstrated that shikonin suppressed the tumor promoter 12‐O‐tetradecanoylphorbol 13‐acetate (TPA) induced neoplastic cell transformation and PKM2 activation in the early stage of carcinogenesis. Mitochondrial functions were inhibited by TPA treatment, as indicated by reduced mitochondrial membrane potential and mitochondrial respiration, which were restored by shikonin. We also examined the levels of lactate as a glycolysis marker, and shikonin suppressed its increase caused by tumor promoter treatment. Modulation of cell metabolism by shikonin was associated with G2–M phase accumulation, and Fra‐1 (a major subunit of activator protein 1 in skin tumorigenesis) downregulation. In addition, we demonstrated that AMP‐activated protein kinase (AMPK), an energy sensor, which is inactivated by TPA, shikonin could reverse AMPK activity. These results suggest that shikonin bears chemopreventive potential for human skin cancers in which PKM2 is upregulated, which might be mediated by inhibiting oncogenic activation, PKM2 activation, and mitochondrial dysfunction. © 2012 Wiley Periodicals, Inc.
IL‐32γ enhances TNF‐α‐induced cell death in colon cancer
Authors: Park Eun‐Seok , Yoo Jae‐Myung , Yoo Hwan‐Soo , Yoon Do‐Young , Yun Yeo‐Pyo , Hong JinTae
Published: December 2012

Interleukin (IL)‐32 is a recently discovered cytokine that appears to play an important role in human colon cancer growth. We investigated that IL‐32γ in combination with TNF‐α remarkably inhibited cell growth of human colon cancer cells (HCT116 and SW620) and tumor growth in xenograft‐bearing nude mice. The transient enforced overexpression of IL‐32γ potentiated the inhibitory effect of TNF‐α on DNA synthesis, cell number and protein content, and enhanced apoptosis in colon cancer cells. We also found that knockdown of IL‐32γ by siRNA showed the abolishment of cell growth inhibitory effect of TNF‐α. The IL‐32γ‐overexpressing colon cancer cells further increased TNF‐α‐mediated expression of p38 MAPK as well as that of Bax, cleaved caspase‐3 and ‐9, but decreased that of antiapoptotic proteins such as Bcl‐2, cellular inhibitor of apoptosis protein (IAP) and X chromosome IAP. In xenograft model, the lipopolysaccharide (LPS)‐injected (1.25 mg/kg) mice inoculated with IL‐32γ‐transfected HCT116 colon cancer cells were more decrease tumor volume and weight than inoculated with vector. Tumor tissues isolated from LPS‐injected mice inoculated with IL‐32γ‐overexpressing colon cancer cells potentiated the expression levels of pro‐apoptotic proteins such as cleaved caspase‐3, 9 and Bax, but decreased that of Bcl‐2. Furthermore, the mice increased IL‐10 production, but decreased IL‐6 levels in serum. In conclusion, our results suggest that IL‐32γ may potentiate TNF‐α‐induced cell growth inhibition through activation of p38 MAPK pathways.