bluuebunny/crossref_metadata_2025_split huggingface dataset:
Insertion of Nitriles into Zirconocene 1‐aza‐1,3‐diene Complexes: Chemoselective Synthesis of N–H and N‐Substituted Pyrroles
Authors: Yu Shasha , Xiong Meijun , Xie Xin , Liu Yuanhong 
Published: September 2014

AbstractThe direct insertion of nitriles into zirconocene‐1‐aza‐1,3‐diene complexes provides an efficient, chemoselective, and controllable synthesis of N‐H and N‐substituted pyrroles upon acidic aqueous work‐up. The outcome of the reaction (that is, the formation of N‐H or N‐substituted pyrroles) results from the different cyclization patterns, which depend on the relative stability and reactivity of the enamine–imine tautomers formed by hydrolysis of the diazazirconacycles.
Edge Detection of Archaeomagnetic Data: a Study from the City of Pisidia Antiocheia, Turkey
Authors: Ar𝚤soy Muzaffer Özgü 
Published: September 2014

ABSTRACTMagnetic survey is one of a number of methods used in archaeological geophysics for detecting and mapping archaeological artefacts and features. Recent magnetic instruments have become both faster and more sensitive as a result of technological and industrial developments. Hence, magnetic methods are becoming an accepted part of archaeological projects. Mapping the edges of magnetic sources is a problem of fundamental importance in magnetic interpretation. Commonly used edge‐detection filters are considerably affected by the presence of noise because this requires the computation of horizontal and vertical derivatives of the magnetic data. Archaeomagnetic data are often dominated by large‐amplitude anomalies that mostly originate from the presence of noise and other environmental effects. Prior to application of the edge‐detection filters, an upward continuation of the archaeomagnetic anomaly or low‐pass filtering may be used to reduce environmental effects. Another useful approach is to apply edge‐detection filters to the pseudogravity‐transformed data. This paper compares the results of common edge‐detection filters applied to the original and pseudogravity‐transformed archaeomagnetic data. In the concept of edge detection, the feasibility and capability of the pseudogravity transformation is demonstrated using a real archaeomagnetic dataset from the ancient city of Pisidia Antiocheia in the province of Isparta (central part of Turkey). Copyright © 2014 John Wiley & Sons, Ltd.
Exclusive Detection of Sub‐Nanomolar Levels of Palladium(II) in Water: An Excellent Probe for Multiple Applications
Authors: Kumari Namita , Dey Nilanjan , Kumar Krishan , Bhattacharya Santanu 
Published: September 2014

AbstractA new colorimetric probe has been developed for the detection and estimation of PdII at sub‐nanomolar concentrations. The probe consisted of rhodamine (signaling unit), which was linked with a bis‐picolyl moiety (binding site) through a phenyl ring. PdII induced opening of the spirolactam ring of the probe with the generation of a prominent pink color. The excellent selectivity of the probe towards PdII over Pd0 or RhII ensured its potential utility for the detection of residual palladium contamination in pharmaceutical drugs and in Pd‐catalyzed reactions. The probe showed a “turn‐on” (bright yellow) fluorescence upon the addition of PdII, which made it suitable for the detection of Pd contaminants in mammalian cells.
Dramatic Mechanistic Change in Acid‐Catalyzed Arylation of Azafulleroids Depending on their Ambident N/C Basicity: Formation of Cyclopentene Centered Pentakisadduct
Authors: Ikuma Naohiko , Doi Yuta , Fujioka Koichi , Mikie Tsubasa , Kokubo Ken , Oshima Takumi 
Published: September 2014

AbstractAzafulleroid, amino‐bridged [5,6]‐open fullerene, has the ambident N/C basicity of the incorporated enamine moiety. Acid‐catalyzed arylation of N‐substituted azafulleroids proceeded via two types of initial N/C protonation to perform monoarylation or 1,4‐bisarylation for the N‐alkyl substituents and shuttlecock‐type pentakisarylation for the N‐phenyl substituent. The dramatic product change was explained by considering the possible mechanism as well as the DFT computational results.
Malaria vaccine candidate antigen targeting the pre‐erythrocytic stage ofPlasmodium falciparumproduced at high level in plants
Authors: Voepel Nadja , Boes Alexander , Edgue Güven , Beiss Veronique , Kapelski Stephanie , Reimann Andreas , Schillberg Stefan , Pradel Gabriele , Fendel Rolf , Scheuermayer Matthias , Spiegel Holger , Fischer Rainer 
Published: September 2014

AbstractPlants have emerged as low‐cost production platforms suitable for vaccines targeting poverty‐related diseases. Besides functional efficacy, the stability, yield, and purification process determine the production costs of a vaccine and thereby the feasibility of plant‐based production. We describe high‐level plant production and functional characterization of a malaria vaccine candidate targeting the pre‐erythrocytic stage ofPlasmodium falciparum. CCT, a fusion protein composed of three sporozoite antigens (P. falciparumcell traversal protein for ookinetes and sporozoites [PfCelTOS],P. falciparumcircumsporozoite protein [PfCSP], andP. falciparumthrombospondin‐related adhesive protein [PfTRAP]), was transiently expressed by agroinfiltration inNicotiana benthamianaleaves, accumulated to levels up to 2 mg/g fresh leaf weight (FLW), was thermostable up to 80°C and could be purified to >95% using a simple two‐step procedure. Reactivity of sera from malaria semi‐immune donors indicated the immunogenic conformation of the purified fusion protein consisting ofPfCelTOS,PfCSP_TSR,PfTRAP_TSR domains (CCT) protein. Total IgG from the CCT‐specific mouse immune sera specifically recognizedP. falciparumsporozoites in immunofluorescence assays and induced up to 35% inhibition in hepatocyte invasion assays. Featuring domains from three promising sporozoite antigens with different roles (attachment and cell traversal) in the hepatocyte invasion process, CCT has the potential to elicit broader immune responses against the pre‐erythrocytic stage ofP. falciparumand represents an interesting new candidate, also as a component of multi‐stage, multi‐subunit malaria vaccine cocktails.
Systematic review of congenital and acquired portal-systemic shunts in otherwise normal livers
Authors: Matthews T J , Trochsler M I , Bridgewater F H , Maddern G J 
Published: September 2014

AbstractBackgroundPortal-systemic shunts (PSSs) are rarely seen in healthy individuals or patients with non-cirrhotic liver disease. They may play an important role in hepatic metabolism as well as in the spread of gastrointestinal metastatic tumours to specific organs. Small spontaneous PSSs may be more common than generally thought. However, epidemiological data are scarce and inconclusive. This systematic review examined the prevalence of reported PSSs and the associated detection methods.MethodsLiterature up to 2011 was reviewed for adult patients with proven congenital or acquired PSSs. Only PSSs in normal livers were analysed for the methods of diagnosis. Eligible studies were identified by searching relevant databases, including PubMed, Embase, MEDLINE and the Cochrane Library. The selection of eligible articles was carried out using predefined inclusion criteria (adult, non-surgical PSS) and a set of search terms that were established before the articles were identified.ResultsEighty studies were included describing 112 patients with congenital or acquired PSSs. The majority were diagnosed incidentally using Doppler ultrasound imaging and CT.ConclusionCongenital and acquired PSSs are rare. They are usually clinically asymptomatic and discovered incidentally by radiological techniques. They may be clinically relevant owing to drug, tumour cell, metabolic and pathogen shunting.
Piloting the Membranolytic Activities of Peptides with a Self‐organizing Map
Authors: Lin Yen‐Chu , Hiss Jan A. , Schneider Petra , Thelesklaf Peter , Lim Yi Fan , Pillong Max , Koehler Fabian M. , Dittrich Petra S. , Halin Cornelia , Wessler Silja , Schneider Gisbert 
Published: September 2014

AbstractAntimicrobial peptides (AMPs) show remarkable selectivity toward lipid membranes and possess promising antibiotic potential. Their modes of action are diverse and not fully understood, and innovative peptide design strategies are needed to generate AMPs with improved properties. We present a de novo peptide design approach that resulted in new AMPs possessing low‐nanomolar membranolytic activities. Thermal analysis revealed an entropy‐driven mechanism of action. The study demonstrates sustained potential of advanced computational methods for designing peptides with the desired activity.
Construction of a Chimeric Biosynthetic Pathway for the De Novo Biosynthesis of Rosmarinic Acid in Escherichia coli
Authors: Bloch Sarah E. , Schmidt‐Dannert Claudia 
Published: September 2014

AbstractHydroxycinnamic acid esters (HCEs) are widely‐distributed phenylpropanoid‐derived plant natural products. Rosmarinic acid (RA), the most well‐known HCE, shows promise as a treatment for cancer and neurological disorders. In contrast to extraction from plant material or plant cell culture, microbial production of HCEs could be a sustainable, controlled means of production. Through the overexpression of a six‐enzyme chimeric bacterial and plant pathway, we show the de novo biosynthesis of RA, and the related HCE isorinic acid (IA), in Escherichia coli. Probing the pathway through precursor supplementation showed several potential pathway bottlenecks. We demonstrated HCE biosynthesis using three plant rosmarinic acid synthase (RAS) orthologues, which exhibited different levels of HCE biosynthesis but produced the same ratio of IA to RA. This work serves as a proof‐of‐concept for a microbial production platform for HCEs by using a modular biosynthetic approach to access diverse natural and non‐natural HCEs.
Immobilized Transition Metals as Catalysts for Cross‐Couplings in Continuous Flow—A Critical Assessment of the Reaction Mechanism and Metal Leaching
Authors: Cantillo David , Kappe C. Oliver 
Published: September 2014

AbstractIn the not too distant future many industrially important chemicals (including pharmaceuticals) will probably be manufactured using continuous flow technology. For a significant number of synthetic steps involved in these protocols transition metal (mostly palladium)‐catalyzed carbon–carbon or carbon–heteroatom bond forming reactions (“cross‐coupling chemistry”) will play an important role. Designing a process for continuous cross‐coupling chemistry involves either the use of a homogeneous or of a heterogeneous (immobilized) catalyst/ligand system. In the latter case, the catalyst/ligand system is typically in the form of a packed‐bed reactor, through which the reaction mixture is pumped, employing an appropriate temperature regime and residence time. Although this approach has been widely popular during the past 15 years, there is growing evidence that suggests that the use of immobilized transition metal catalysts for performing cross‐coupling chemistry in continuous flow is, in fact, not very practical. As demonstrated in this review, significant leaching of the transition metal out of the packed‐bed catalyst will almost inevitably occur, leading to decreased catalyst activity and contamination of the product with transition metal. This is a consequence of the well‐known fact that the reaction mechanism for these kinds of transformations is (quasi)homogeneous and involves the transformation of a Pd0 species into a (soluble) PdII species. Using an immobilized catalyst in a batch protocol the transient leaching of palladium will not be immediately obvious, as, after completion of the catalytic cycle, Pd0 will typically redeposit onto the support. In contrast, in continuous flow mode, the palladium metal will progressively be “chromatographed” through the packed‐bed catalyst until, ultimately, all palladium will be removed from the support. This effect typically will become only evident when long run experiments are performed. The preferred alternative, in particular for larger scale experiments, is to use a homogeneous (pre)catalyst in combination with an appropriate catalyst recycling technology.
Visible‐Light‐Driven Alcohol Dehydrogenation with a Rhodium Catalyst
Authors: Kagalwala Husain N. , Maurer Andrew B. , Mills Isaac N. , Bernhard Stefan 
Published: September 2014

AbstractWe report the photocatalytic dehydrogenation of alcohols with a Rh catalyst and I− in an acidic medium. The catalyst screening of a structurally diverse family of Rh complexes found [RhIII(dtbbpy)2(OSO2CF3)2](CF3SO3) (Rh7; dtbbpy=4,4′‐di‐tert‐butyl‐2,2′‐bipyridine) to be the best catalyst. All components (Rh7, HI, alcohol, and light) were found to be essential for the dehydrogenation to occur. Under optimal conditions, generation of both H2 and acetone (for isopropyl alcohol) was observed, which increased linearly for 4 days with no significant decrease in activity. The proposed mechanism involves the formation of [RhIII(dtbbpy)2(I)2]+ [Rh7(a)] followed by the generation of photoinduced I3− via a ligand (I−) to metal (RhIII) charge transfer. The resulting RhI species reduces H+ and I3− oxidizes the alcohol, which completes the catalytic cycle. Supporting evidence for the catalytic mechanism was obtained by using UV/Vis spectroscopy, electrospray ionization mass spectrometry, cyclic voltammetry and time‐dependent DFT calculations.
Biosorption of Trivalent Chromium from Wastewater: An Approach towards Green Chemistry
Authors: Kanagaraj James , Senthilvelan Thamizharasan , Panda Ramesh C. , Aravindhan Rathinam , Mandal Asit B. 
Published: September 2014

AbstractChromium is one of the metals used in industry that create environmental toxicity and pollution problems. In the present study, chromium in wastewater was removed by a biosorption method using a bacterial culture of Bacillus pumilus. A mathematical model representing the biosorption kinetics was formulated, supporting the Langmuir isotherm for the adsorption of chromium. Fourier transform infrared and scanning electron microscopy studies were used to characterize the adsorption of chromium by the bacterial biomass. The analysis of pollution parameters (chemical oxygen demand, total organic content, total dissolved solid, total suspended solid) suggest a significant reduction of the pollution load. The results show that the method developed here is very effective for the removal of chromium from an aqueous environment.
Numerical Investigation of Three‐Dimensional Bubble Column Flows: A Detached Eddy Simulation Approach
Authors: Masood Rao M. A. , Delgado Antonio 
Published: September 2014

AbstractNumerical simulations were performed employing detached eddy simulation (DES) in a three‐dimensional transient Euler‐Euler framework for bubble columns, and all the computational fluid dynamics results were compared with a k‐ϵ model and available experimental data. The numerical results are in good agreement with the experiments in predicting the time‐averaged axial velocity and turbulent kinetic energy profiles. The flow‐resolving capabilities of the DES model are highlighted, and it is shown that the DES turbulence model can be efficiently used for simulating flow field and turbulent quantities in the case of bubble columns.
Energy‐Efficient Size Reduction Technology for Wet Fibrous Biomass Treatment in Industrial Biofuel Technologies
Authors: Kratky Lukas , Jirout Tomas 
Published: September 2014

AbstractBiomass size reduction belongs to the high energy‐consuming operations in industrial biofuel technologies. Its energy requirement actually ranges from hundreds to thousands of kilowatt‐hours per ton of dry biomass. These high energy values are primarily caused by energy demand of disintegrators used for wet fibrous biomass. Therefore, the reduction of this energy requirement could significantly improve the whole process economics. Suitable disintegrators were searched and several potential industrial technologies of mechanical disintegration for wet fibrous biomass with respect to minimum energy demand were designed. Wet wheat straw served as model material to evaluate their energy requirements. The technology with the least energy demand was composed of a new, fully developed retting mill.
Supercapacitive Behavior of Two Glucose‐Derived Microporous Carbons: Direct Pyrolysis versus Hydrothermal Carbonization
Authors: Sevilla Marta , Yu Linghui , Ania Conchi O. , Titirici Maria‐Magdalena 
Published: September 2014

AbstractThe physical and chemical characteristics of activated carbons produced from glucose and hydrothermally carbonized glucose are compared for the first time, as well as their performance as electrodes in supercapacitors with aqueous electrolyte (H2SO4). Both KOH‐activated carbons exhibit similar textural properties, with Brunauer–Emmett–Teller surface areas of ≈1400–1500 m2 g−1 and a pore volume of ≈0.70 cm3 g−1, with the pore size distribution centered in the micropore range. When tested as supercapacitor electrodes, the activated carbon produced from hydrothermally carbonized glucose exhibits a superior rate capability, owing to lower equivalent distributed resistance (being able to work at an ultrahigh discharge current of 90 A g−1), as well as higher specific capacitance (≈240 F g−1 vs. ≈220 F g−1 for the glucose‐derived activated carbon at 0.1 A g−1). Both supercapacitors have excellent robustness, even for a large cell voltage of 1.2 V in 1 M H2SO4.
Isoxazole‐Embedded Allylic Zinc Reagent for the Diastereoselective Preparation of Highly Functionalized Aldol‐Type Derivatives Bearing a Stereocontrolled Quaternary Center
Authors: Klier Lydia , Diène Coura R. , Schickinger Manuel , Metzger Albrecht , Wagner Andreas J. , Karaghiosoff Konstantin , Marek Ilan , Knochel Paul 
Published: September 2014

AbstractHighly functionalized aldol‐type products bearing a β‐quaternary center and a stereoselectively controlled γ‐hydroxy function are readily prepared by the diastereoselective addition of an allylic zinc reagent embedded in an isoxazole ring to various aromatic and heteroaromatic aldehydes, in the presence of Lewis acids, such as MgCl2 or LaCl3⋅2 LiCl. After reductive cleavage of the NO bond by using Fe, NH4Cl, aldol‐type products bearing a stereocontrolled β‐quaternary center and a γ‐hydroxy group were observed. The benzylic reactivity of the isoxazolylmethylzinc reagent towards other electrophiles, such as acid chlorides, aryl and allylic halides, as well as aldehydes in the presence of BF3⋅OEt2 are also described.
Control of Excitation and Quenching in Multi‐colour Electrogenerated Chemiluminescence Systems through Choice of Co‐reactant
Authors: Barbante Gregory J. , Kebede Noah , Hindson Christopher M. , Doeven Egan H. , Zammit Elizabeth M. , Hanson Graeme R. , Hogan Conor F. , Francis Paul S. 
Published: September 2014

AbstractWe demonstrate a new approach to manipulate the selective emission in mixed electrogenerated chemiluminescence (ECL) systems, where subtle changes in co‐reactant properties are exploited to control the relative electron‐transfer processes of excitation and quenching. Two closely related tertiary‐amine co‐reactants, tri‐n‐propylamine and N,N‐diisopropylethylamine, generate remarkably different emission profiles: one provides distinct green and red ECL from [Ir(ppy)3] (ppy=2‐phenylpyridinato‐C2,N) and a [Ru(bpy)3]2+ (bpy=2,2′‐bipyridine) derivative at different applied potentials, whereas the other generates both emissions simultaneously across a wide potential range. These phenomena can be rationalized through the relative exergonicities of electron‐transfer quenching of the excited states, in conjunction with the change in concentration of the quenchers over the applied potential range.
Photochemical, Electrochemical, and Photoelectrochemical Water Oxidation Catalyzed by Water‐Soluble Mononuclear Ruthenium Complexes
Authors: Li Ting‐Ting , Zhao Wei‐Liang , Chen Yong , Li Fu‐Min , Wang Chuan‐Jun , Tian Yong‐Hua , Fu Wen‐Fu 
Published: September 2014

AbstractTwo mononuclear ruthenium complexes [Ru(H2tcbp)(isoq)2] (1) and [Ru(H2tcbp)(pic)2] (2) (H4tcbp=4,4′,6,6′‐tetracarboxy‐2,2′‐bipyridine, isoq=isoquinoline, pic=4‐picoline) are synthesized and fully characterized. Two spare carboxyl groups on the 4,4′‐positions are introduced to enhance the solubility of 1 and 2 in water and to simultaneously allow them to tether to the electrode surface by an ester linkage. The photochemical, electrochemical, and photoelectrochemical water oxidation performance of 1 in neutral aqueous solution is investigated. Under electrochemical conditions, water oxidation is conducted on the deposited indium‐tin‐oxide anode, and a turnover number higher than 15,000 per water oxidation catalyst (WOC) 1 is obtained during 10 h of electrolysis under 1.42 V vs. NHE, corresponding to a turnover frequency of 0.41 s−1. The low overpotential (0.17 V) of electrochemical water oxidation for 1 in the homogeneous solution enables water oxidation under visible light by using [Ru(bpy)3]2+ (P1) (bpy=2,2′‐bipyridine) or [Ru(bpy)2(4,4′‐(COOEt)2‐bpy)]2+ (P2) as a photosensitizer. In a three‐component system containing 1 or 2 as a light‐driven WOC, P1 or P2 as a photosensitizer, and Na2S2O8 or [CoCl(NH3)5]Cl2 as a sacrificial electron acceptor, a high turnover frequency of 0.81 s−1 and a turnover number of up to 600 for 1 under different catalytic conditions are achieved. In a photoelectrochemical system, the WOC 1 and photosensitizer are immobilized together on the photoanode. The electrons efficiently transfer from the WOC to the photogenerated oxidizing photosensitizer, and a high photocurrent density of 85 μA cm−2 is obtained by applying 0.3 V bias vs. NHE.
Catalytic Asymmetric Synthesis of Alkynyl Aziridines: Both Enantiomers of cis‐Aziridines from One Enantiomer of the Catalyst
Authors: Guan Yong , López‐Alberca Maria P. , Lu Zhenjie , Zhang Yu , Desai Aman A. , Patwardhan Aniruddha P. , Dai Yijing , Vetticatt Mathew J. , Wulff William D. 
Published: September 2014

AbstractAlkynyl aziridines can be obtained from the catalytic asymmetric aziridination (AZ reaction) of alkynyl imines with diazo compounds in high yields and high asymmetric inductions mediated by a chiral boroxinate or BOROX catalyst. In contrast to the AZ reaction with aryl‐ and alkyl‐substituted imines, alkynyl imines react to give cis‐substituted aziridines with both diazo esters and diazo acetamides. Remarkably, however, the two diazo compounds give different enantiomers of the cis‐aziridine from the same enantiomer of the catalyst. Theoretical considerations of the possible transition states for the enantiogenic step reveal that the switch in enantiomers results from a switch from Si‐face to Re‐face addition to the imine, which in turn is related to a switch from reaction with an E‐imine in the former and a Z‐isomer of the imine in the latter.
Quantitative Insight into the Design of Compounds Recognized by the L‐Type Amino Acid Transporter 1 (LAT1)
Authors: Ylikangas Henna , Malmioja Kalle , Peura Lauri , Gynther Mikko , Nwachukwu Emmanuel O. , Leppänen Jukka , Laine Krista , Rautio Jarkko , Lahtela‐Kakkonen Maija , Huttunen Kristiina M. , Poso Antti 
Published: September 2014

AbstractL‐Type amino acid transporter 1 (LAT1) is a transmembrane protein expressed abundantly at the blood–brain barrier (BBB), where it ensures the transport of hydrophobic acids from the blood to the brain. Due to its unique substrate specificity and high expression at the BBB, LAT1 is an intriguing target for carrier‐mediated transport of drugs into the brain. In this study, a comparative molecular field analysis (CoMFA) model with considerable statistical quality (Q2=0.53, R2=0.75, Q2 SE=0.77, R2 SE=0.57) and good external predictivity (CCC=0.91) was generated. The model was used to guide the synthesis of eight new prodrugs whose affinity for LAT1 was tested by using an in situ rat brain perfusion technique. This resulted in the creation of a novel LAT1 prodrug with L‐tryptophan as the promoiety; it also provided a better understanding of the molecular features of LAT1‐targeted high‐affinity prodrugs, as well as their promoiety and parent drug. The results obtained will be beneficial in the rational design of novel LAT1‐binding prodrugs and other compounds that bind to LAT1.