bluuebunny/crossref_metadata_2025_split huggingface dataset:
High‐Resolution Imaging of the Initial Stages of Oxidation of Cu(111) with Scanning Electrochemical Potential Microscopy
Authors: Traunsteiner Christoph , Tu Kaiyang , Kunze‐Liebhäuser Julia 
Published: October 2014

AbstractScanning electrochemical potential microscopy (SECPM) is a scanning probe technique for the detection of the electrochemical double‐layer (EDL) potential of a given working electrode (WE). We report the first high‐resolution imaging of the OH adsorbate structure formed on a Cu(111) WE in alkaline solution with SECPM, which reveals a structural parameter of (0.60±0.04) nm that is in excellent agreement with that found with electrochemical scanning tunneling microscopy. The origin of the potential used as a feedback signal in SECPM mode is discussed, focusing on leakage currents detected in the SECPM setup, faradaic reactions in the electrolyte, and electron‐tunneling processes between the tip and the WE. At potential set‐points that are typical for SECPM measurements, the potential detected with the tip is found to originate from a tunneling current. Therefore, the images recorded with SECPM cannot deliver information on the EDL potential at the WE surface in the present case.
1,n‐Hydrogen‐Atom Transfer (HAT) Reactions in Which n≠5: An Updated Inventory
Authors: Nechab Malek , Mondal Shovan , Bertrand Michèle P. 
Published: October 2014

AbstractHydrogen‐atom transfer (HAT) counts amongst the most widely investigated routes to carbon‐centered radicals. Intramolecular processes involving 1,5‐HAT are widespread to promote regioselective radical “CH activation”. The aim of this review is to draw up a comprehensive inventory of the less commonly encountered 1,n‐radical translocations (n≠5) with the aim to update this topic with the most recent relevant data.
A Highly Selective Two‐Photon Fluorescent Probe for Detection of Cadmium(II) Based on Intramolecular Electron Transfer and its Imaging in Living Cells
Authors: Shi Zhaohua , Han Qingxin , Yang Lizi , Yang Huan , Tang Xiaoliang , Dou Wei , Li Zhiqi , Zhang Yange , Shao Yongliang , Guan Liping , Liu Weisheng 
Published: October 2014

AbstractA new quinoline‐based probe was designed that shows one‐photon ratiometric and two‐photon off–on changes upon detecting Cd2+. It exhibits fluorescence emission at 407 nm originating from quinoline groups in Tris‐HCl (25 mM, pH 7.40), H2O/EtOH (8:2, v/v). Coordination with Cd2+ causes quenching of the emission at 407 nm and simultaneously yields a remarkable redshift of the emission maximum to 500 nm with an isoemissive point at 439 nm owing to an intramolecular charge‐transfer mechanism. Thus, dual‐emission ratiometric measurement with a large redshift (Δλ=93 nm) and significant changes in the ratio (F500/F439) of the emission intensity (R/R0 up to 27) is established. Moreover, the sensor H2L displays excellent selectivity response, high sensitive fluorescence enhancement, and strong binding ability to Cd2+. Coordination properties of H2L towards Cd2+ were fully investigated by absorption/fluorescence spectroscopy, which indicated the formation of a 2:1 H2L/Cd2+ complex. All complexes were characterized by X‐ray crystallography, and TD‐DFT calculations were performed to understand the origin of optical selectivity shown by H2L. Two‐photon fluorescence microscopy experiments have demonstrated that H2L could be used in live cells for the detection of Cd2+.
Picolinamides as Effective Ligands for Copper‐Catalysed Aryl Ether Formation: Structure–Activity Relationships, Substrate Scope and Mechanistic Investigations
Authors: Sambiagio Carlo , Munday Rachel H. , Marsden Stephen P. , Blacker A. John , McGowan Patrick C. 
Published: October 2014

AbstractThe use of picolinic acid amide derivatives as an effective family of bidentate ligands for copper‐catalysed aryl ether synthesis is reported. A fluorine‐substituted ligand gave good results in the synthesis of a wide range of aryl ethers. Even bulky phenols, known to be very challenging substrates, were shown to react with aryl iodides with excellent yields using these ligands. At the end of the reaction, the first examples of end‐of‐life Cu species were isolated and identified as CuII complexes with several of the anionic ligands tested. A preliminary mechanistic investigation is reported that suggests that the substituents on the ligands might have a crucial role in determining the redox properties of the metal centre and, consequently, its efficacy in the coupling process. An understanding of these effects is important for the development of new efficient and tunable ligands for copper‐based chemistry.
Formal Total Synthesis of (−)‐Taxol through Pd‐Catalyzed Eight‐Membered Carbocyclic Ring Formation
Authors: Hirai Sho , Utsugi Masayuki , Iwamoto Mitsuhiro , Nakada Masahisa 
Published: October 2014

AbstractA formal total synthesis of (−)‐taxol by a convergent approach utilizing Pd‐catalyzed intramolecular alkenylation is described. Formation of the eight‐membered carbocyclic ring has been a problem in the convergent total synthesis of taxol but it was solved by the Pd‐catalyzed intramolecular alkenylation of a methyl ketone affording the cyclized product in excellent yield (97 %), indicating the high efficiency of the Pd‐catalyzed intramolecular alkenylation. Rearrangement of the epoxy benzyl ether through a 1,5‐hydride shift, generating the C3 stereogenic center and subsequently forming the C1–C2 benzylidene, was discovered and utilized in the preparation of a substrate for the Pd‐catalyzed reaction.
Reactions of the Donor‐Stabilized Silylene Bis[N,N′‐diisopropyl‐benzamidinato(−)]silicon(II) with Brønsted Acids
Authors: Junold Konstantin , Sinner Katharina , Baus Johannes A. , Burschka Christian , Fonseca Guerra Célia , Bickelhaupt F. Matthias , Tacke Reinhold 
Published: October 2014

AbstractReaction of the donor‐stabilized silylene 1 (which is three‐coordinate in the solid state and four‐coordinate in solution) with [HMCp(CO)3] (M=Mo, W; Cp=cyclopentadienyl) leads to the cationic five‐coordinate silicon(IV) complexes 2 and 3, respectively, and reaction of 1 with CH3COOH yields the neutral six‐coordinate silicon(IV) complex 4. Compounds 2–4 were structurally characterized by crystal structure analyses and multinuclear NMR spectroscopic studies in the solid state and in solution. The formation of 2–4 can be formally described in terms of a Brønsted acid/base reaction, coupled with a redox process (SiII→SiIV, H+→H−).
Combining Experimental and Computational Studies to Understand and Predict Reactivities of Relevance to Homogeneous Catalysis
Authors: Tsang Althea S.‐K. , Sanhueza Italo A. , Schoenebeck Franziska 
Published: October 2014

AbstractThis article showcases three major uses of computational chemistry in reactivity studies: the application after, in combination with, and before experiment. Following a brief introduction of suitable computational tools, challenges and opportunities in the implementation of computational chemistry in reactivity studies are discussed, exemplified with selected case studies from our and other laboratories.
Methyl Substitution Regulates the Enantioselectivity of Supramolecular Complex Binding to Human Telomeric G‐Quadruplex DNA
Authors: Xu Bailu , Zhao Chuanqi , Chen Yong , Tateishi‐Karimata Hisae , Ren Jinsong , Sugimoto Naoki , Qu Xiaogang 
Published: October 2014

AbstractChiral supramolecular compounds with substituents at different positions show different binding properties with human telomeric G‐quadruplex DNA. These different positions of methyl substitution in chiral supramolecular compounds can modulate their enantioselectivity and structural preference when binding with human telomeric G‐quadruplex DNA.
Enantiopure Laterally Functionalized Alleno–Acetylenic Macrocycles: Synthesis, Chiroptical Properties, and Self‐Assembly in Aqueous Media
Authors: Tzirakis Manolis D. , Alberti Mariza N. , Weissman Haim , Rybtchinski Boris , Diederich François 
Published: October 2014

AbstractA family of shape‐persistent alleno–acetylenic macrocycles (SPAAMs), peripherally decorated with structurally diverse pendant groups, has been synthesized and characterized in enantiomerically pure form. Their electronic circular dichroism (ECD) spectra feature a strong chiroptical response, which is more than two times higher than for open‐chain tetrameric analogues. A water‐soluble oligo(ethylene glycol)‐appended SPAAM undergoes self‐assembly in aqueous solution. Morphology studies by cryogenic transmission electron microscopy (cryo‐TEM) revealed the formation of aggregates with fibrous fine structures that correspond to tubular, macrocyclic stacks.
A 3D 12‐Ring Zeolite with Ordered 4‐Ring Vacancies Occupied by (H2O)2 Dimers
Authors: Liang Jie , Su Jie , Wang Yingxia , Chen Yanping , Zou Xiaodong , Liao Fuhui , Lin Jianhua , Sun Junliang 
Published: October 2014

AbstractA germanate zeolite, PKU‐14, with a three‐ dimensional large‐pore channel system was structurally characterized by a combination of high‐resolution powder X‐ray diffraction, rotation electron diffraction, NMR, and IR spectroscopy. Ordered Ge4O4 vacancies inside the [46.612] cages has been found in PKU‐14, in which a unique (H2O)2 dimer was located at the vacancies and played a structure‐directing role. It is the first time that water clusters are found to be templates for ordered framework vacancies.
Management trends in stage I testicular seminoma: Impact of race, insurance status, and treatment facility
Authors: Gray Phillip J. , Lin Chun Chieh , Sineshaw Helmneh , Paly Jonathan J. , Jemal Ahmedin , Efstathiou Jason A. 
Published: October 2014

BACKGROUNDThe management of stage I testicular seminoma is evolving rapidly. This study examined modern trends in the management of stage I testicular seminoma and the effects of sociodemographic factors on therapy choice.METHODSData from the National Cancer Data Base on 34,067 patients with stage I testicular seminoma who were treated between 1998 and 2011 were analyzed. Multivariate logistic regression models were used to assess factors associated with adjuvant management strategies.RESULTSFor patients with stage IA/B testicular seminoma, rates of observation after orchiectomy increased from 23.7% to 54.0%, the receipt of adjuvant chemotherapy increased from 1.5% to 16.0%, and the receipt of radiotherapy decreased from 70.8% to 28.8%. A similar pattern was seen in stage IS testicular seminoma, although these patients were more likely to receive adjuvant radiotherapy/chemotherapy (60.7% vs 44.8% for stage IA/B in 2011, P < .001). For patients with stage IA/B testicular seminoma, observation after orchiectomy was more common in racial minorities (odds ratio [OR] for blacks vs whites, 1.31, P < .001; OR for Hispanics vs whites, 1.39, P < .001) and in the uninsured (OR for uninsured vs privately insured, 1.33, P < .001) and less common at community centers (OR for community centers vs National Cancer Institute–designated cancer centers, 0.80, P = .044). In those with stage IA/B testicular seminoma who received adjuvant radiotherapy/chemotherapy, the receipt of chemotherapy was more common at academic centers and for patients with nonprivate insurance.CONCLUSIONSPostorchiectomy observation in stage I testicular seminoma has increased significantly in recent years, as has the receipt of chemotherapy, whereas the receipt of radiotherapy has declined, particularly at academic centers. Race, insurance status, and facility type are strongly associated with the choice of adjuvant management. Cancer 2015;121:681–687. © 2014 American Cancer Society.
Dark‐Field‐Based Observation of Single‐Nanoparticle Dynamics on a Supported Lipid Bilayer for In Situ Analysis of Interacting Molecules and Nanoparticles
Authors: Lee Young Kwang , Kim Sungi , Nam Jwa‐Min 
Published: October 2014

AbstractObservation of single plasmonic nanoparticles in reconstituted biological systems allows us to obtain snapshots of dynamic processes between molecules and nanoparticles with unprecedented spatiotemporal resolution and single‐molecule/single‐particle‐level data acquisition. This Concept is intended to introduce nanoparticle‐tethered supported lipid bilayer platforms that allow for the dynamic confinement of nanoparticles on a two‐dimensional fluidic surface. The dark‐field‐based long‐term, stable, real‐time observation of freely diffusing plasmonic nanoparticles on a lipid bilayer enables one to extract a broad range of information about interparticle and molecular interactions throughout the entire reaction period. Herein, we highlight important developments in this context to provide ideas on how molecular interactions can be interpreted by monitoring dynamic behaviors and optical signals of laterally mobile nanoparticles.
Forced Folding of a Disordered Protein Accesses an Alternative Folding Landscape
Authors: Moosa Mahdi Muhammad , Ferreon Allan Chris M. , Deniz Ashok A. 
Published: October 2014

AbstractIntrinsically disordered proteins (IDPs) are involved in diverse cellular functions. Many IDPs can interact with multiple binding partners, resulting in their folding into alternative ligand‐specific functional structures. For such multi‐structural IDPs, a key question is whether these multiple structures are fully encoded in the protein sequence, as is the case in many globular proteins. To answer this question, here we employed a combination of single‐molecule and ensemble techniques to compare ligand‐induced and osmolyte‐forced folding of α‐synuclein. Our results reveal context‐dependent modulation of the protein′s folding landscape, suggesting that the codes for the protein′s native folds are partially encoded in its primary sequence, and are completed only upon interaction with binding partners. Our findings suggest a critical role for cellular interactions in expanding the repertoire of folds and functions available to disordered proteins.
Selenium–Selenium Bond Cleavage of Diaryl Diselenide Radical Anions During Pulse Radiolysis
Authors: Tojo Sachiko , Fujitsuka Mamoru , Ouchi Akihiko , Majima Tetsuro 
Published: October 2014

AbstractA seleniumselenium σ‐bond (SeSe) cleavage of a diaryl diselenide radical anion (ArSeSeAr.−) was investigated by absorption measurements during the γ radiolysis and pulse radiolysis in 2‐methyltetrahydrofuran. A di‐α‐naphthyl diselenide radical anion (αNpSeSeαNp.−) in which an unpaired electron is localized in the SeSe σ* orbital between both Se atoms with an elongated SeSe bond showed an absorption band at 440 nm at 77 K. Upon increasing temperature, the absorption band at 440 nm shifted to 540 nm, thus suggesting that an unpaired electron is delocalized over two naphthalene rings and the SeSe bond. The disappearance of the absorption band at 540 nm and formation of absorption bands at 420, 620, and 690 nm assigned to the α‐naphthylselenyl radical were observed during the pulse radiolysis of αNpSeSeαNp, thus indicating that the SeSe bond cleavage occurred in αNpSeSeαNp.−. The relationship between the SeSe bond cleavage and delocalization of the unpaired electron in ArSeSeAr.− is discussed.
Role of Side‐Chain Bioisosteres in Determining the Binding Affinity of Click Chemistry Derived RGD Peptidomimetics to αvβ3 Integrin
Authors: Fabbrizzi Pierangelo , Menchi Gloria , Raspanti Silvia , Guarna Antonio , Trabocchi Andrea 
Published: October 2014

AbstractTriazole‐containing Arg‐Gly‐Asp (RGD) peptidomimetics capable of interacting with αvβ3 integrin were developed through click chemistry. The role of the diverse range of guanidine bioisosteres for the arginine mimetic moiety was evaluated in vitro together with different appendages on the aspartic acid side of the peptidomimetic. The corresponding azides and alkynes were constructed through the application of simple modular reactions. Integrin binding assays allowed the best guanidine bioisostere for binding activity to be selected; the aromatic ring at the azide fragment bearing the aspartic acid moiety proved to be unnecessary. Molecular modelling calculations of a hit compound showed that the triazole and 2‐aminopyridine rings were involved in important π‐stacking interactions with Tyr178.
Solid Mixed‐Metal‐Oxide Catalysts for Biodiesel Production: A Review
Authors: Chang Fei , Zhou Quan , Pan Hu , Liu Xiao‐Fang , Zhang Heng , Xue Wei , Yang Song 
Published: October 2014

AbstractWith the rapid economic development and increasing depletion of petroleum‐derived diesel, survival environment of the human has been a serious threat. Therefore, it is necessary to seek green, environmentally friendly, and renewable energy candidates, for which biodiesel fuel has been developed as a promising candidate for energy accommodation. Currently, the most applied approach for the production of biodiesel involves the esterification and/or transesterification reaction. Among various catalytic processes, heterogeneous catalysts are promising and receiving increasing attention due to the easy separation of products and catalysts as well as the high‐purity glycerine (glycerol) byproduct that avoids significant waste emissions and effectively reduces the environmental pollution. In this Review, an attempt is being made to review different types of catalytic systems mediated by solid mixed metal oxides for biodiesel production.
Synergistic effect of sustained release of growth factors and dynamic culture on osteoblastic differentiation of mesenchymal stem cells
Authors: Porta Giovanna Della , Nguyen Bao‐Ngoc B. , Campardelli R. , Reverchon Ernesto , Fisher John P. 
Published: October 2014

AbstractMicroparticles have been utilized as delivery vehicles of soluble factors to modify cellular behavior and therefore enhance tissue engineering regeneration. When incorporated into three‐dimensional systems, microparticles can provide geometrical and temporal controlled release of bioactive agents, such as growth factors (GFs) to surrounding cells. This study investigates the effect of GFs release from biopolymer microparticles on osteoblastic differentiation of human mesenchymal stem cells (hMSCs) encapsulated in calcium (Ca)‐alginate scaffolds while cultured in a tubular perfusion system bioreactor system. Empirical and deterministic models were used to demonstrate that poly(d,l‐lactic‐co‐glycolic acid)‐encapsulated GFs would result in a delayed release profile compared to GFs encapsulated into scaffolds directly. We hypothesized that the dual delivery of human bone‐morphogenetic protein 2 (hBMP2) and human vascular endothelial growth factor to cells in dynamic culture would provide molecular and physical cues to promote differentiation. Results indicated that the exposures of hBMP2 and dynamic flow are sufficient in enhancing the osteoblastic differentiation pathway compared to no GF addition and static culture. The GF delivery system in a dynamic flow environment resulted in a synergistic effect on osteoblastic differentiation of hMSCs. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 2161–2171, 2015.
Synthesis and Characterization of Metal Complexes (M = Al, Ti, W, Zn) Containing Pyrrole‐imine Ligands
Authors: Chen Yu‐Cai , Chiu Wan‐Ting , Hu Ting‐Jia , Lin Chia‐Her , Huang Jui‐Hsien 
Published: October 2014

AbstractA series of metal compounds (M = Al, Ti, W, and Zn) containing pyrrole‐imine ligands have been prepared and structurally characterized. The reactions of AlMe3 with one and three equivs of pyrrole‐imine ligand [C4H3NH‐(2‐CH=NCH2Ph)] (1) generated aluminum compounds Al[C4H3N‐(2‐CH=NCH2Ph)]Me2 (2) and Al[C4H3N‐(2‐CH=NCH2Ph)]3 (3), respectively, in relatively high yield. Reacting two equivs of 1 with Ti(OiPr)4, W(NHtBu)2(=NtBu)2, or ZnMe2 afforded Ti[C4H3N‐(2‐CH=NCH2Ph)]2(OiPr)2 (4), W[C4H3N‐(2‐CH=NCH2Ph)]2(=NtBu)2 (5), and Zn[C4H3N‐(2‐CH=NCH2Ph)]2 (6), respectively. All the compounds have been characterized by 1H and 13C NMR spectroscopy. Compounds 3–6 have also been characterized by single‐crystal X‐ray structural analysis. The biting angles of pyrrole‐imine ligand with metals decrease and their related MNpyrrole and MNimine bond lengths increase in the order of 6, 3, 4, and 5.
Precisely Tailor the Longitudinal Localized Surface Plasmon Resonance of Gold Nanorods by Mild Oxidation with NaNO2
Authors: Jia Yanghui , Xiong Bin , Xu Dong , Yeung Edward S. , He Yan 
Published: October 2014

AbstractIn this work, we introduce a new method to precisely tailor the longitudinal localized surface plasmon resonance (LLSPR) wavelengths of gold nanorods (GNRs) through the use of NaNO2 as the oxidant. The effects of the concentrations of NaNO2, NH4Br and HCl on the reaction kinetics were investigated separately. To prepare GNRs with desired LLSPR wavelengths, equations were derived and were proved to be able to guide the tailoring of the LLSPR wavelengths through carefully tuning either the amount of NaNO2 or the reaction time. TEM characterizations performed on two representative sets of GNRs show that the GNRs obtained exhibited shortened lengths but unchanged diameter with good monodispersity. In particular, GNRs with targeted LLSPR at 800 nm, 750 nm, 700 nm and 650 nm were successfully synthesized with relative errors of only 1 %∼5 %. This method shall promote more applications of GNRs and may advance the synthesis of other metal nanoparticles.
Synthesis and Characterization of Melamine Formaldehyde Resins for Decorative Paper Applications
Authors: Ullah S. , Bustam M. A. , Ahmad F. , Nadeem M. , Naz M. Y. , Sagir M. , Shariff A. M. 
Published: October 2014

AbstractMelamine‐formaldehyde (MF) resins of improved environmental compatibility were synthesized at different molar ratios, temperature and pH. Five molar ratios of melamine and formaldehyde: 35:65, 36.5:63.5, 38.3:61.7, 41.1:58.9 and 42.4:58.6 were used to synthesize the corresponding resins. The prepared samples were characterized by using molecular weight determination viscometery, field emission scanning electron microscopy and thermogravimetric analysis. It was noticed that the solid content in the resin increases with an increase in pH. The maximum percentage of the solid content (51 %) was obtained for pH of 8.5 and temperature range of 95–98 oC. The refractive index of the final product was found increasing with an increase of melamine concentration in the resin. A similar trend was noticed in molecular weight of the resins with an increase in monomer yield. The maximum molecular weight of 114218 was obtained from the sample synthesized with MF molar ratio of 42.4:58.6.
Forensic Applications of Portable X‐ray Fluorescence Spectrometer: Glass Samples
Authors: Cheng Shih‐Yuan , Chen Yung‐Fou , Huang Chih‐Chun Jean 
Published: October 2014

AbstractPortable X‐ray Fluorescence Spectrometer (PXRF) is a qualitative and semi‐quantitative elemental analysis method. Recently, many researches using PXRF in the elemental analysis of materials have been reported. However, PXRF has not been extensively applied in forensic science, thus this study is devoted to demonstrate the utility of this technique through a rapid elemental analysis of glass samples for preliminary glass discrimination. Major elements such as Si, O, Ca, Al, and Na, as well as traces of Sr, Rb, K, Fe and Sn, in 25 glass samples were analyzed by PXRF. The amounts of some elements, such as Fe, K, Zr, and Sr, vary in different samples, while other elements, such as Th, are consistent in most tested glass samples. The results show that we can discriminate 98.31 % of 7,500 pair‐wise comparisons created from 25 glass samples. This study establishes PXRF as a new rapid method for the preliminary elemental analysis of glass, which shows a potential to be further applied for discrimination of glass samples in forensic field.