bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seasonal Variation on the Contents of Coumarin and Kaurane‐Type Diterpenes in Mikania laevigata and M. glomerata Leaves under Different Shade Levels
Authors: Bertolucci Suzan Kelly V. , Pereira Ana Bárbara D. , Pinto José Eduardo B. P. , Oliveira Alaíde B. , Braga Fernão C. 
Published: February 2013

AbstractCoumarin (1) and kaurane‐type diterpenes are considered the bioactive constituents of Mikania glomerata and M. laevigata, used in Brazil to treat respiratory affective disorders. The seasonal variation of 1, ortho‐coumaric acid (2), benzoylgrandifloric acid (3), cinnamoylgrandifloric acid (4), and kaurenoic acid (5) in leaves of both species, cultivated in full sunlight and under shade levels of 40 and 80%, was quantified by HPLC. Compound 2 was detected solely in M. laevigata in concentrations below the limit of quantification. Coumarin was not found in M. glomerata, whereas its concentration reached 0.94±0.24% (w/w) in M. laevigata farmed in summer under 80% shading. Both Mikania species produced higher amounts of kaurane diterpenes when cultivated in plenty of sunlight. Hence, maximum contents of 1 are reached in M. laevigata cultivated under high shading, but with reduced concentrations of 3–5. Conversely, M. glomerata should be cultivated under full sunlight and harvested in winter for highest concentrations of kaurane‐type diterpenes.
Cytotoxic and Apoptosis‐Inducing Activities of Steviol and Isosteviol Derivatives against Human Cancer Cell Lines
Authors: Ukiya Motohiko , Sawada Shingo , Kikuchi Takashi , Kushi Yasunori , Fukatsu Makoto , Akihisa Toshihiro 
Published: February 2013

AbstractSeventeen steviol derivatives, i.e., 2–18, and 19 isosteviol derivatives, i.e., 19–37, were prepared from a diterpenoid glycoside, stevioside (1). Upon evaluation of the cytotoxic activities of these compounds against leukemia (HL60), lung (A549), stomach (AZ521), and breast (SK‐BR‐3) cancer cell lines, nine steviol derivatives, i.e., 5–9 and 11–14, and five isosteviol derivatives, i.e., 28–32, exhibited activities with single‐digit micromolar IC50 values against one or more cell lines. All of these active compounds possess C(19)‐O‐acyl group, and among which, ent‐kaur‐16‐ene‐13,19‐diol 19‐O‐4′,4′,4′‐trifluorocrotonate (14) exhibited potent cytotoxicities against four cell lines with IC50 values in the range of 1.2–4.1 μM. Compound 14 induced typical apoptotic cell death in HL60 cells upon evaluation of the apoptosis‐inducing activity by flow‐cytometric analysis. These results suggested that acylation of the 19‐OH group of kaurane‐ and beyerane‐type diterpenoids might be useful for enhancement of their cytotoxicities with apoptosis‐inducing activity.
Structural Insights into the Recovery of Aldolase Activity in N‐Acetylneuraminic Acid Lyase by Replacement of the Catalytically Active Lysine with γ‐Thialysine by Using a Chemical Mutagenesis Strategy
Authors: Timms Nicole , Windle Claire L. , Polyakova Anna , Ault James R. , Trinh Chi H. , Pearson Arwen R. , Nelson Adam , Berry Alan 
Published: February 2013

AbstractChemical modification has been used to introduce the unnatural amino acid γ‐thialysine in place of the catalytically important Lys165 in the enzyme N‐acetylneuraminic acid lyase (NAL). The Staphylococcus aureus nanA gene, encoding NAL, was cloned and expressed in E. coli. The protein, purified in high yield, has all the properties expected of a class I NAL. The S. aureus NAL which contains no natural cysteine residues was subjected to site‐directed mutagenesis to introduce a cysteine in place of Lys165 in the enzyme active site. Subsequently chemical mutagenesis completely converted the cysteine into γ‐thialysine through dehydroalanine (Dha) as demonstrated by ESI‐MS. Initial kinetic characterisation showed that the protein containing γ‐thialysine regained 17 % of the wild‐type activity. To understand the reason for this lower activity, we solved X‐ray crystal structures of the wild‐type S. aureus NAL, both in the absence of, and in complex with, pyruvate. We also report the structures of the K165C variant, and the K165‐γ‐thialysine enzyme in the presence, or absence, of pyruvate. These structures reveal that γ‐thialysine in NAL is an excellent structural mimic of lysine. Measurement of the pH‐activity profile of the thialysine modified enzyme revealed that its pH optimum is shifted from 7.4 to 6.8. At its optimum pH, the thialysine‐containing enzyme showed almost 30 % of the activity of the wild‐type enzyme at its pH optimum. The lowered activity and altered pH profile of the unnatural amino acid‐containing enzyme can be rationalised by imbalances of the ionisation states of residues within the active site when the pKa of the residue at position 165 is perturbed by replacement with γ‐thialysine. The results reveal the utility of chemical mutagenesis for the modification of enzyme active sites and the exquisite sensitivity of catalysis to the local structural and electrostatic environment in NAL.
Long‐term clinical outcomes with the use of a modified provisional Jailed‐Balloon stenting technique for the treatment of nonleft main coronary bifurcation lesions
Authors: Depta Jeremiah P. , Patel Yogesh , Patel Jayendrakumar S. , Novak Eric , Yeung Michael , Zajarias Alan , Kurz Howard I. , Lasala John M. , Bach Richard G. , Singh Jasvindar 
Published: February 2013

ObjectivesTo assess the long‐term clinical outcomes associated with treatment of nonleft main coronary bifurcation lesions using a modified provisional jailed‐balloon technique (JBT).BackgroundPercutaneous coronary intervention (PCI) of bifurcation lesions is associated with a higher risk of adverse events, including the risk of side branch (SB) loss during main branch (MB) stenting.MethodsFrom 4/2003 to 8/2010, 406 patients with 424 nonleft main coronary bifurcation lesions underwent PCI with (n = 95) and without (n = 311) the use of JBT. Rates of SB loss and long term clinical outcomes [death, myocardial infarction (MI), and target lesion revascularization (TLR)] were compared between patients undergoing PCI with and without JBT using univariate and propensity score adjusted and matched analyses.ResultsThe majority of patients presented with acute coronary syndrome (63%) and 90% of lesions were Medina class 1,1,1. Patients were followed for a mean of 2.7 ± 2.1 years. After propensity score matching (n = 81 in each group), JBT was associated with a significantly lower composite rate of death, MI, or TLR (HR 0.22, 95% CI 0.06–0.76; P = 0.02) and TLR (HR 0.20, 95% 0.04–0.92; P = 0.04) compared with no JBT. Permanent SB loss was significantly lower in the JBT group compared with no JBT group (OR 0.22, 95% CI 0.10–0.49; P = 0.0001).ConclusionsThe use of JBT for the treatment of nonleft main coronary bifurcation lesions was associated with significantly lower rates of SB loss and major adverse cardiac events at late follow‐up. © 2013 Wiley Periodicals, Inc.
Application of Bismuth‐Impregnated Mesoporous Silica to the Photochemical Oxidation of Methylene Blue: An Example of Nanoparticle Autocatalysis
Authors: Ward Antony J. , Weber Cameron C. , Masters Anthony F. , Maschmeyer Thomas 
Published: February 2013

AbstractA range of Bi‐TUD‐1 silicas were used in conjunction with H2O2 to mediate the photochemical oxidation of methylene blue (MB). The rate of MB degradation increased sequentially with decreasing metal loading, and it was determined experimentally that singlet oxygen was responsible for the oxidation process observed. Kinetic studies of the system revealed that putative reactive BiV‐containing surface sites are generated autocatalytically by irradiation of the Bi‐TUD‐1 in the presence of peroxide. The formation of these active sites is favored by lower Bi concentrations resulting in the formation of smaller Bi species in the silica framework. Total organic carbon analysis of the reaction mixtures showed that MB was being converted to CO2 after the decolorization process had occurred.
Bingel–Hirsch Addition on Endohedral Metallofullerenes: Kinetic Versus Thermodynamic Control
Authors: Alegret Núria , Rodríguez‐Fortea Antonio , Poblet Josep M. 
Published: February 2013

AbstractAn extensive theoretical study of the Bingel–Hirsch addition of bromomalonate on scandium nitride endohedral fullerenes has been carried out. The prototypical and highly symmetrical Sc3N@Ih‐C80, with a structure that satisfies the isolated pentagon rule (IPR), and the non‐IPR Sc3N@D3(6140)‐C68 fullerene show analogous reaction paths despite the distinct topology of the carbon networks and different rotation freedom of the internal nitride cluster. For the two metallofullerenes, our results predict that the reaction takes place under kinetic control yielding open‐cage fulleroids on [6,6] bonds, which is in good agreement with experimental data. The theoretical studies also show that predicting the reactivity of endohedral metallofullerenes is not straightforward and often an accurate analysis of the potential energy surface is required.
Enantioselective Total Synthesis of (−)‐Diversonol
Authors: Tietze Lutz F. , Jackenkroll Stefan , Raith Christian , Spiegl Dirk A. , Reiner Johannes R. , Ochoa Campos Maria Claudia 
Published: February 2013

AbstractFor the synthesis of (−)‐diversonol (ent‐1), an enantioselective domino‐Wacker/carbonylation/methoxylation reaction and an enantioselective Wacker oxidation were used to give the chroman in high yield and 96 % and 93 % ee, respectively. Dihydroxylation at the vinyl moiety using the Sharpless procedure and a Wittig–Horner reaction followed by hydrogenation, benzylic oxidation, and an intramolecular acylation provided the tetrahydroxanthenone, from which ent‐1 is accessible in a few steps. Furthermore, the synthesis of the diastereomeric diversonol rac‐1,9 a‐epi‐diversonol (rac‐41) is also described.
The 2‐Cyano‐2,2‐dimethylethanimine‐N‐oxymethyl Group for the 2′‐Hydroxyl Protection of Ribonucleosides in the Solid‐Phase Synthesis of RNA Sequences
Authors: Cieślak Jacek , Ausín Cristina , Grajkowski Andrzej , Beaucage Serge L. 
Published: February 2013

AbstractThe reaction of 2‐cyano‐2‐methyl propanal with 2′‐O‐aminooxymethylribonucleosides leads to stable and yet reversible 2′‐O‐(2‐cyano‐2,2‐dimethylethanimine‐N‐oxymethyl)ribonucleosides. Following N‐protection of the nucleobases, 5′‐dimethoxytritylation and 3′‐phosphitylation, the resulting 2′‐protected ribonucleoside phosphoramidite monomers are employed in the solid‐phase synthesis of three chimeric RNA sequences, each differing in their ratios of purine/pyrimidine. When the activation of phosphoramidite monomers is performed in the presence of 5‐benzylthio‐1H‐tetrazole, coupling efficiencies averaging 99 % are obtained within 180 s. Upon completion of the RNA‐chain assemblies, removal of the nucleobase and phosphate protecting groups and release of the sequences from the solid support are carried out under standard basic conditions, whereas the cleavage of 2′‐O‐(2‐cyano‐2,2‐dimethylethanimine‐N‐oxymethyl) protective groups is effected (without releasing RNA alkylating side‐products) by treatment with tetra‐n‐butylammonium fluoride (0.5 m) in dry DMSO over a period of 24–48 h at 55 °C. Characterization of the fully deprotected RNA sequences by polyacrylamide gel electrophoresis (PAGE), enzymatic hydrolysis, and matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry confirmed the identity and quality of these sequences. Thus, the use of 2′‐O‐aminooxymethylribonucleosides in the design of new 2′‐hydroxyl protecting groups is a powerful approach to the development of a straightforward, efficient, and cost‐effective method for the chemical synthesis of high‐quality RNA sequences in the framework of RNA interference applications.
A Simple Link between Hydrocarbon and Borohydride Chemistries
Authors: Poater Jordi , Solà Miquel , Viñas Clara , Teixidor Francesc 
Published: February 2013

AbstractA clear link between the hydrocarbon and borohydride chemistries is established by showing that hydrocarbons and borohydrides have a common root regulated by the number of valence electrons in a confined space. Application of the proposed method to archetypal hydrocarbons leads to well‐known borohydrides but, more importantly, it allows the design of new and interesting boron‐containing molecules that can be a source of inspiration for synthetic chemists.
Heterogeneous Nucleophilic Transformation of Metolachlor by Bisulfide on Alumina Surface
Authors: Wei Lan , Li Fangbai , Liu Chengshuai , Liu Chuanping , Chen Manjia , Lan Qing 
Published: February 2013

AbstractThe present research elucidates the accelerating effect of alumina minerals on metolachlor transformation using sulfur nucleophiles and also determines the metolachlor transformation mechanisms in the heterogeneous reaction systems. Metolachlor transformation was first systematically investigated under different conditions. Then, the Fourier transform infrared (FTIR) spectra were used to characterize the changes in the surface bonds of the aluminas. The transformation products were qualitatively identified using LC/MS. The results showed that bisulfide can produce efficient metolachlor transformation rates, and the presence of the aluminas can further accelerate the transformation by achieving complete transformation in <21 days. In addition, a higher pH and higher bisulfide concentration are more favorable for metolachlor transformation. When normalized to the surface area, the metolachlor transformation rates were found to follow the order of α‐Al2O3>γ‐AlOOH>γ‐Al2O3 in the presence of different aluminas. FTIR results indicated that the enhancement of metolachlor transformation rates by bisulfide with aluminas can be attributed to the surface active nucleophiles on alumina surfaces formed through AlS and AlO bonds. The substitution of chlorine on the metolachlor followed the SN2 mechanism by bisulfide with accelerated rate through mediating the heterogeneous reactions with aluminas.
Detection of Toxoplasma gondii in Turkish River and Drinking Water Samples by Different PCR and LAMP Methods
Authors: Koloren Zeynep , Demirel Elif 
Published: February 2013

AbstractIn this study, we investigated the occurence of Toxoplasma gondii and checked the sequencing in 56 samples collected from in the Ordu province, Middle Black Sea, Turkey. The samples were collected from drinking and river water and DNA was extracted from all samples. After DNA isolation, the 18S rRNA target gene and B1 gene of T. gondii were amplified by conventional PCR, nested PCR, and loop‐mediated isothermal amplification (LAMP) assay, respectively. Twenty out of 56 samples (35.7%) were Toxoplasma positive by LAMP. The conventional PCR and nested PCR confirmed that 12 and 16 out of 56 samples (21.42 and 28.57%) were positive for Toxoplasma, respectively. All drinking water samples were negative by all three methods. Thirteen Toxoplasma nested PCR products were successfully sequenced. This study achieved detection and sequencing of Toxoplasma from water supplies in the Middle Black sea area in Turkey.
Modulation of c‐Met signaling and cellular sensitivity to radiation
Authors: Bhardwaj Vikas , Cascone Tina , Cortez Maria Angelica , Amini Arya , Evans Jaden , Komaki Ritsuko U. , Heymach John V. , Welsh James W. 
Published: February 2013

AbstractThe c‐Met/hepatocyte growth factor receptor and its family members are known to promote cancer cell migration and invasion. Signaling within and beyond this pathway contributes to the systemic spread of metastases through induction of the epithelial‐mesenchymal transition, a process also implicated in mediating resistance to current anticancer therapies, including radiation. Induction of c‐Met has also been observed after irradiation, suggesting that c‐Met participates in radiation‐induced disease progression through the epithelial‐mesenchymal transition. Therefore, c‐Met inhibition is an attractive target for potentially mitigating radiation resistance. This article summarizes key findings regarding crosstalk between radiotherapy and c‐Met and discusses studies performed to date in which c‐Met inhibition was used as a strategy to increase cellular radiosensitivity. Cancer 2013. © 2013 American Cancer Society.
A QoS‐aware service discovery method for elastic cloud computing in an unstructured peer‐to‐peer network
Authors: Lin Wenmin , Dou Wanchun , Xu Zhanyang , Chen Jinjun 
Published: February 2013

SUMMARYTraditionally, service discovery is often promoted by the centralized approach that typically suffers from single point of failure, poor reliability, poor scalability, to name a few. In view of this challenge, a QoS‐aware service discovery method is investigated for elastic cloud computing in an unstructured peer‐to‐peer network in this paper. Concretely speaking, the method is deployed by two phases, that is, service registering phase and service discovery phase. More specifically, for a peer node engaged in the unstructured peer‐to‐peer network, it firstly registers its functional and nonfunctional information to its neighbors in a flooding way. With the multiple registered information, the QoS‐aware service discovery is promoted in a probabilistic flooding way according to the network traffic. At last, extensive simulations are conducted to evaluate the feasibility of our method. Copyright © 2013 John Wiley & Sons, Ltd.
Direct Selective Hydrogenation of Phenol and Derivatives over Polyaniline‐Functionalized Carbon‐Nanotube‐Supported Palladium
Authors: Chen Jinzhu , Zhang Wei , Chen Limin , Ma Longlong , Gao Hui , Wang Tiejun 
Published: February 2013

AbstractInvited for this month′s cover are the groups of Prof. Jinzhu Chen and Prof. Longlong Ma from the Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences. The image shows a bifunctional stabilizing mechanism of the composite support PANI/CNT on palladium nanoparticles in the catalyst Pd–PANI/CNT, and how the PANI/CNT can play a role in controlling the conversion and selectivity in the direct hydrogenation of phenol to cyclohexanone.
Fabrication and photocatalytic property of ZnO/SrTiO3 core/shell nanorod arrays
Authors: Tu Y. F. , Fu Q. M. , Niu X. J. , Sang J. P. , Tan Z. J. , Zheng G. , Zou X. W. 
Published: February 2013

AbstractZnO/SrTiO3 core/shell nanorod arrays were fabricated by a facile two‐step method. ZnO nanorod arrays were first hydrothermally grown on Si substrate. Then, using liquid phase deposition method, SrTiO3 were deposited onto the ZnO nanorods to form core/shell nanorod structures. The morphologies and structures of the products were characterized by scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction. The photocatalytic behavior of the nanorod arrays was also examined through the photodegradation of methylene blue solution under UV irradiation. It was found that the core/shell nanorod arrays with deposition time of 10 min showed higher photocatalytic activity than bare ZnO nanorod arrays. This enhancement was attributed to the efficient charge separation at the ZnO/SrTiO3 interface.
Low Temperature Hetero‐Epitaxial Growth of 3C‐SiC Films on Si Utilizing Microwave Plasma CVD
Authors: Zhuang Hao , Zhang Lei , Staedler Thorsten , Jiang Xin 
Published: February 2013

AbstractMicrowave plasma (MW)CVD is used for the first time in the low‐temperature, hetero‐epitaxial growth of 3C‐SiC films on Si using a gas mixture of tetramethylsilane (TMS) and hydrogen. Good epitaxial matching between the 3C‐SiC film and Si substrate is obtained in the epitaxially grown 3C‐SiC films. Further investigation reveals that microwave powder density and substrate temperature play an important role in the determination of the orientation, SiC/Si interface structure, and morphology of 3C‐SiC films. The presented results show MWCVD might be a potent approach in the future in obtaining large‐scale, high‐quality, single‐crystalline 3C‐SiC films.
One‐Pot Synthesis of Pyrrolo[3,4‐a]indolizine‐1,3‐diones through [3+2] Cycloaddition‐Oxidation Reaction Catalyzed by CuII Salt and O2 as the Oxidant
Authors: Liu Yun , Hu Hua‐You , Su Xian‐Bin , Sun Jin‐Wei , Cao Chang‐Sheng , Shi Yan‐Hui 
Published: February 2013

AbstractAn efficient one‐pot synthesis of pyrrolo[3,4‐a]indolizine‐1,3‐diones has been developed from maleimides, pyridines, and acyl bromides through a [3+2] cyclization–oxidation reaction catalyzed by CuII salt under O2 atmosphere. The advantage of this method is the use of molecular oxygen as the oxidant, in the presence of a catalytic amount of hydrated copper(II) chloride, to accomplish the reaction with broad substrate scope and excellent yields.
Palladium‐Catalyzed Sonogashira Reaction for the Synthesis of Arylalkynecarboxylic Acids from Aryl Bromides at Low Temperature
Authors: Park Kyungho , You Jung‐Min , Jeon Seungwon , Lee Sunwoo 
Published: February 2013

AbstractA variety of aryl bromides were coupled with propiolic acid in the presence of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) and catalyst Pd(PPh3)4 to afford the corresponding arylalkynecarboxylic acids in good yields at low temperature. This method showed good tolerance toward functional groups such as alkoxy, ketone, ester, aldehyde, cyano, nitro, and hydroxy. Under these conditions, propiolic acid showed higher reactivity than any other compound containing terminal alkyne groups. According to the mechanistic studies, the key reaction step for the high reactivity of propiolic acid might be ligand exchange between the acetylide and bromide at palladium, and/or reductive elimination, but not the oxidative addition step.
Use of novel phenyl‐hexyl core‐shell particles in nano‐LC
Authors: Fanali Salvatore , Rocchi Silvia , Chankvetadze Bezhan 
Published: February 2013

This paper reports the use of novel phenyl‐hexyl core‐shell particles packed into fused silica capillaries in nano‐LC. Capillary columns of different id of 25, 50, 75, 100, and 150 μm were packed employing the slurry packing method. The columns were used for the separation of a model mixture containing five aromatic hydrocarbons. Benzene, toluene, ethylbenzene, n‐propylbenzene, and n‐butylbenzene were separated utilizing an isocratic elution mode. Mixtures of water/ACN at different ratio were studied to find optimal experimental conditions for baseline separation of all sample components. As expected with this novel stationary phase, an RP chromatographic mechanism was observed. A mixture of water/ACN, 30:70, v/v allowed the complete resolution of the studied analytes. Efficiency increased by decreasing the capillary id recording the highest number of plates per meter with capillaries of 25 μm id. The decrease of the column id also resulted in a flatter dependence of the plate numbers on the linear flow rate of the mobile phase allowing the increase of the flow rate of the mobile phase without significant decrease of efficiency.
Evaluation of phytotoxicity and genotoxicity of nitrobenzene with A battery of Vicia Faba assay system
Authors: Ma Jun , Guo Donglin , Su Wenyue , Wang Dan , Guo Changhong 
Published: February 2013

Abstract

Nitrobenzene (NB) is an important organic compound intermediate that is used widely in industry. In the present study, to evaluate the phytotoxicity and genotoxicity of NB on plants, Vicia faba was exposed to increasing concentrations of NB (5 mg L−1, 10 mg L−1, 25 mg L−1, 50 mg L−1, and 100 mg L−1). The data revealed that germination rate and radicle length of V. faba seedlings were promoted by low NB concentrations and short exposure periods, whereas these parameters were inhibited at greater NB concentrations and longer exposures. When assessed by mitotic index, micronucleus, and chromosomal aberration assays, NB showed dose-dependent genotoxicity at 0 mg L−1 to 50 mg L−1. Environ Toxicol Chem 2013;32:1426–1432. © 2013 SETAC