bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Efficient One‐Pot Synthesis of Substituted 1H‐Naphtho[2,1‐b]pyrans and 4H‐1‐Benzopyrans (=Chromenes) under Solvent‐Free Microwave‐Irradiation Conditions
Authors: Shekhar Adimulam Chandra , Kumar Akula Ravi , Sathaiah Gangaram , Raju Kengiri , Rao Pamulaparthy Shanthan , Sridhar Madabhushi , Narsaiah Banda , Srinivas Punnamraju Venkata Satya Surya , Sridhar Balasubramanian 
Published: March 2012

AbstractA facile heterogeneous synthesis of 3‐amino‐1‐aryl‐1H‐naphtho[2,1‐b]pyran and 2‐amino‐4‐aryl‐4H‐1‐benzopyran derivatives 3 and 5, respectively, was carried out efficiently by one‐pot three‐component coupling of an aromatic aldehyde 1, an active methylene compound 2, and naphthalen‐2‐ol or a phenol 4 in the presence of 5‐Å molecular sieves under solvent‐free microwave‐irradiation conditions (Scheme 1 and 2, Tables 1 and 2). The catalyst was recovered and recycled (Table 3).
Abieseconordines A and B, Two Novel Norditerpenoids with a 18‐Nor‐5,10 : 9,10‐disecoabietane Skeleton from Abies forrestii
Authors: Yu Ping , Zhang Shou‐De , Li Yong‐Li , Yang Xian‐Wen , Zeng Hua‐Wu , Li Hong‐Lin , Zhang Wei‐Dong 
Published: March 2012

AbstractA systematic phytochemical investigation on Abies forrestii afforded two new and 20 known compounds. Abieseconordines A and B (1 and 2) are the first two examples of norditerpenes with a novel 18‐nor‐5,10 : 9,10‐disecoabietane skeleton. Their structures were established mainly by analysis of 1D‐ and 2D‐NMR spectroscopic data. In addition, electronic circular‐dichroism calculations and molecular‐orbital analysis were utilized to confirm the absolute configuration of 1. Both compounds exhibited a potent effect in a bioassay inhibiting LPS‐stimulated NO production in RAW264.7 macrophages.
Rapid Synthesis of Novel and Known Coumarin‐3‐carboxylic Acids Using Stannous Chloride Dihydrate under Solvent‐Free Conditions
Authors: Karami Bahador , Farahi Mahnaz , Khodabakhshi Saeed 
Published: March 2012

AbstractVarious coumarin‐3‐carboxylic acid (=2‐oxo‐2H‐1‐benzopyran‐3‐carboxylic acid; CcaH) derivatives have been synthesized in good yields using catalytic amounts of SnCl2⋅2 H2O under solvent‐free conditions. This inexpensive, nontoxic, and readily available catalytic system (10 mol‐%) efficiently catalyzes the Knoevenagel condensation and intramolecular cyclization of various 2‐hydroxybenzaldehydes or acetophenones with Meldrum's acid. High product yields, use of inexpensive and safe catalyst, and solvent‐free conditions display both economic and environmental advantages.
Substrate Range of the Titanium TADDOLate Catalyzed Asymmetric Fluorination of Activated Carbonyl Compounds
Authors: Bertogg Andreas , Hintermann Lukas , Huber Dominique P. , Perseghini Mauro , Sanna Maria , Togni Antonio 
Published: March 2012

AbstractThe substrate range of the [TiCl2(TADDOLate)] (TADDOL=α,α,α′,α′‐tetraaryl‐1,3‐dioxolane‐4,5‐dimethanol)‐catalyzed asymmetric α‐fluorination of activated β‐carbonyl compounds has been investigated. Optimal conditions for catalysis are characterized by using 5 mol‐% of TiCl2(naphthalen‐1‐yl)‐TADDOLate) as catalyst in a saturated (0.14 mol/l) MeCN solution of F‐TEDA (1‐(chloromethyl)‐4‐fluoro‐1,4‐diazoniabicyclo[2.2.2]octane bis‐[tetrafluoroborate]) at room temperature. A series of α‐methylated β‐keto esters (3‐oxobutanoates, 3‐oxopentanoates) with bulky benzyl ester groups (60–90% ee) or phenyl ester (67–88% ee) have been fluorinated readily, whereas α‐acyl lactones were also readily fluorinated, but gave lower inductions (13–46% ee). Double stereochemical differentiation in β‐keto esters with chiral ester groups raised the stereoselectivity to a diastereomeric ratio (dr) of up to 96.5 : 3.5. For the first time, β‐keto S‐thioesters were asymmetrically fluorinated (62–91.5% ee) and chlorinated (83% ee). Lower inductions were observed in fluorinations of 1,3‐diketones (up to 40% ee) and β‐keto amides (up to 59% ee). General strategies for preparing activated β‐carbonyl compounds as important model substrates for asymmetric catalytic α‐functionalizations are presented (>60 examples).
Polyhydroxylated Steroids from the South China Sea Gorgonian Anthogorgia sp.
Authors: Sun Peng , Xu Yuanyuan , Liu Taofang , Tang Hua , Yi Yanghua , Krohn Karsten , Li Ling , Zhang Wen 
Published: March 2012

AbstractFour new polyhydroxylated steroids, namely anthogorgsteroids A–D (1–4), were isolated from the South China Sea gorgonian Anthogorgia sp. The structures of these compounds were elucidated by detailed spectroscopic analyses and comparison with reported data.
Photocyclodimers of ‘Made‐to‐Measure’ Seven‐ and Six‐Membered Cyclic Enones
Authors: Schmidt Kerstin , Margaretha Paul 
Published: March 2012

AbstractOn irradiation (350 nm) in benzene as solvent, dioxepinone 6 and benzoxepinone 7 afford quantitatively mixtures of two diastereoisomeric head‐to‐head dimers, respectively. In both cases, on contact with SiO2 the minor dimer containing trans‐ring fusions undergoes spontaneous isomerization to the (major) cis‐transoid‐cis diastereoisomer. In contrast, thiopyranone 8 is converted selectively, but in very low yield, to dimer 13.
Synthesis of Bis‐Heterocyclic 1H‐Imidazole 3‐Oxides from 3‐Oxido‐1H‐imidazole‐4‐carbohydrazides
Authors: Pieczonka Adam Marek , Mlostoń Grzegorz , Heimgartner Heinz 
Published: March 2012

AbstractThe reaction of 1H‐imidazole‐4‐carbohydrazides 1, which are conveniently accessible by treatment of the corresponding esters with NH2NH2⋅H2O, with isothiocyanates in refluxing EtOH led to thiosemicarbazides (=hydrazinecarbothioamides) 4 in high yields (Scheme 2). Whereas 4 in boiling aqueous NaOH yielded 2,4‐dihydro‐3H‐1,2,4‐triazole‐3‐thiones 5, the reaction in concentrated H2SO4 at room temperature gave 1,3,4‐thiadiazol‐2‐amines 6. Similarly, the reaction of 1 with butyl isocyanate led to semicarbazides 7, which, under basic conditions, undergo cyclization to give 2,4‐dihydro‐3H‐1,2,4‐triazol‐3‐ones 8 (Scheme 3). Treatment of 1 with Ac2O yielded the diacylhydrazine derivatives 9 exclusively, and the alternative isomerization of 1 to imidazol‐2‐ones was not observed (Scheme 4). It is important to note that, in all these transformations, the imidazole N‐oxide residue is retained. Furthermore, it was shown that imidazole N‐oxides bearing a 1,2,4‐triazole‐3‐thione or 1,3,4‐thiadiazol‐2‐amine moiety undergo the S‐transfer reaction to give bis‐heterocyclic 1H‐imidazole‐2‐thiones 11 by treatment with 2,2,4,4‐tetramethylcyclobutane‐1,3‐dithione (Scheme 5).
In vivo and in vitro evidence for an association between the route‐specific transmission of HHV‐8 and the virus genotype
Authors: Matteoli Barbara , Broccolo Francesco , Scaccino Antonio , Cottoni Francesca , Angeloni Antonio , Faggioni Alberto , Ceccherini‐Nelli Luca 
Published: March 2012

AbstractThe study was performed to determine if there is an association between the genotype and transmission of HHV‐8 types A and C. These HHV‐8 subtypes are prevalent in the area of North of Sardinia, which is an island off west Italy's mainland that has a high HHV‐8 seroprevalence (35%). Blood and saliva samples from 30 patients with classic Kaposi's sarcoma who were lifetime residents of North Sardinia were analyzed to identify the HHV‐8 genotype and quantitate the viral load. Genotype A, especially A1 subtype, was found more frequently (9/30 patients) and had a significantly higher viral load in saliva compared to blood (P = 0.029), where type C was found more frequently but with a viral load lower than 103 copies/ml. To determine if there is a correlation between the viral genotype and cellular tropism, type A1 and C3 HHV‐8 viral particles were obtained from cell lines BCBL1 and BC3 infected chronically with HHV‐8 A1 and C3 genotypes respectively and used to infect HEK293 epithelial origin cells and PBMCs in vitro. The data indicate that the A1 HHV‐8 genotype is tropic and replicates at higher levels in the epithelial cell lines. J. Med. Virol. 84:786–791, 2012. © 2012 Wiley Periodicals, Inc.
Risk factors for hepatitis C virus infection in Inland Brazil: An analysis of pooled epidemiological sectional studies
Authors: Souto Francisco José Dutra , Fontes Cor Jésus Fernandes , Pignati Luara Teófilo , Pagliarini Maria Emiliana Sarno , Menezes Valfredo da Mota , Martinelli Ana de Lourdes Candolo , Figueiredo José Fernando de Castro , Donadi Eduardo Antonio , Passos Afonso Diniz 
Published: March 2012

AbstractIn order to assess the contribution of different parenteral routes as risk exposure to the hepatitis C virus (HCV), samples from nine surveys or cross‐sectional studies conducted in two Brazilian inland regions were pooled, including a total of 3,910 subjects. Heterogeneity among the study results for different risk factors was tested and the results were shown to be homogeneous. Anti‐HCV antibodies were observed in 241 individuals, of which 146 (3.7%, 95% CI = 3.2–4.4) had HCV exposure confirmed by immunoblot analysis or PCR test. After adjustment for relevant variables, a correlation between confirmed HCV exposure and injection drug use, tattooing, and advance age was observed. In a second logistic model that included exposures not searched in all nine studies, a smaller sample was analyzed, revealing an independent HCV association with past history of surgery and males who have sex with other males, in addition to repeated injection drug use. Overall, these analyses corroborate the finding that injection drug use is the main risk factor for HCV exposure and spread, in addition to other parenteral routes. J. Med. Virol. 84:756–762, 2012. © 2012 Wiley Periodicals, Inc.
A Bayesian approach to detecting change points in climatic records
Authors: Ruggieri Eric 
Published: March 2012

AbstractGiven distinct climatic periods in the various facets of the Earth's climate system, many attempts have been made to determine the exact timing of ‘change points’ or regime boundaries. However, identification of change points is not always a simple task. A time series containing N data points has approximately Nk distinct placements of k change points, rendering brute force enumeration futile as the length of the time series increases. Moreover, how certain are we that any one placement of change points is superior to the rest? This paper introduces a Bayesian Change Point algorithm which provides uncertainty estimates both in the number and location of change points through an efficient probabilistic solution to the multiple change point problem. To illustrate its versatility, the Bayesian Change Point algorithm is used to analyse both the NOAA/NCDC annual global surface temperature anomalies time series and the much longer δ18O record of the Plio‐Pleistocene. Copyright © 2012 Royal Meteorological Society
Breaking away: A new model for innovation
Authors: Stevenson Jane , Kaafarani Bilal 
Published: March 2012

AbstractInnovation is an often‐misunderstood practice, according to Stevenson and Kaafarani. To be truly categorized as innovation, a product, company, or service must be unique; must deliver tangible value to the customer; and must be commercially viable. Their research uncovered four categories of innovation: transformational, category, marketplace, and operational. Each of these has defining characteristics and its own business attributes. Leaders must also find answers for the three Ws—who will buy, what is involved in development, and why will it make business sense to proceed.
The end of diversity: How leaders make differences really matter
Authors: Davidson Martin N. 
Published: March 2012

AbstractLeaders who recognize the importance of diversity but treat it as a separate topic are not getting the full power of the concept, according to Davidson. The key is what he refers to as “Leveraging Difference.” He poses a provocative question: “What if the most important leadership activity was to catalyze diversity, not just manage it?” Leaders thus become emboldened to re‐vision everything they do. Such leaders connect to people who are different from them—those who may be considered informal leaders, or what he refers to as “leaders from the margin.”
Inspiring democracy in the workplace: From fear‐based to freedom‐centered organizations
Authors: Fenton Traci L. 
Published: March 2012

AbstractMost of us would prefer to work in an environment ruled by democratic principles rather than one ruled by command and fear. Yet, unfortunately, according to Fenton, too many people still toil in the latter environment. Her research shows great benefits for organizations operating along democratic lines, such as lower absenteeism, better customer service, and more innovation. These workplaces are also generally better able to attract top talent, especially from Generation Y. She includes examples of democratic companies and provides a chart of democratic principles, including transparency, integrity, and accountability.
Medical costs and health‐care resource use in patients with inflammatory myopathies in an insured population
Authors: Furst Daniel E. , Amato Anthony A. , Iorga Şerban R. , Bancroft Tim , Fernandes Ancilla W. 
Published: March 2012

AbstractIntroduction:In this study we determined the health‐care costs and resource utilization associated with idiopathic inflammatory myopathies (IIMs) in a large managed care plan in the USA.Methods:Myositis subjects ≥18 years of age with claims‐based evidence of IIMs were identified from a health plan database. Subjects were matched with unaffected controls, and costs and resource use were determined during a 12‐month period.Results:A total of 1781 newly diagnosed IIM subjects were matched to 5343 controls, and 2697 subjects with existing disease were matched to 8091 controls. Mean overall annual medical costs were higher among newly diagnosed subjects ($16,319 vs. $4926, P < 0.001) and subjects with an existing IIM ($15,539 vs. $5210, P < 0.001) in comparison to controls. IIM subjects had significantly higher mean counts of ambulatory visits, specialist visits, and inpatient hospital stays compared with controls (all P < 0.001).Conclusion:Our analysis suggests that IIMs have increased medical costs and resource use. Muscle Nerve 46: 496–505, 2012
Solution NMR structure of the ribosomal protein RP‐L35Ae from Pyrococcus furiosus
Authors: Snyder David A. , Aramini James M. , Yu Bomina , Huang Yuanpeng J. , Xiao Rong , Cort John R. , Shastry Ritu , Ma Li‐Chung , Liu Jinfeng , Rost Burkhard , Acton Thomas B. , Kennedy Michael A. , Montelione Gaetano T. 
Published: March 2012

AbstractThe ribosome consists of small and large subunits each composed of dozens of proteins and RNA molecules. However, the functions of many of the individual protomers within the ribosome are still unknown. In this article, we describe the solution NMR structure of the ribosomal protein RP‐L35Ae from the archaeon Pyrococcus furiosus. RP‐L35Ae is buried within the large subunit of the ribosome and belongs to Pfam protein domain family PF01247, which is highly conserved in eukaryotes, present in a few archaeal genomes, but absent in bacteria. The protein adopts a six‐stranded anti‐parallel β‐barrel analogous to the “tRNA binding motif” fold. The structure of the P. furiosus RP‐L35Ae presented in this article constitutes the first structural representative from this protein domain family. Proteins 2012. © 2012 Wiley Periodicals, Inc.
Laser‐induced front side etching of fused silica with KrF excimer laser using thin chromium layers
Authors: Lorenz Pierre , Ehrhardt Martin , Zimmer Klaus 
Published: March 2012

AbstractLaser‐induced front side etching (LIFE) is a method for laser etching of transparent materials using thin absorber layers. This approach is a straightforward advancement of the back side etching techniques. Within this study the etching of fused silica with thin chromium layers as radiation absorbers is presented using nanosecond KrF excimer laser with a wavelength of 248 nm. The laser fluence up to 10 J/cm2, the number of pulses up to 10 as well as the layer thickness from 2 to 250 nm is varied. The treated fused silica was analysed with microscopic (white light interferometry, WLI, scanning electron microscopy, SEM) and spectroscopic methods (energy‐dispersive X‐ray spectroscopy (EDX)).magnified image
Schematic illustration of the LIFE process.The LIFE method allows the nm‐precision etching (rms ≤ 8 nm) of fused silica at moderate laser fluences (2–6 J/cm2).
Mechanism of high temperature hydrogen reduced polarization degradation in Pb(Zr1−xTix)O3 ferroelectric thin film capacitors
Authors: Hui Wenyuan , Chen Zhihui , Liu Xiaobing , Jiang Anquan 
Published: March 2012

AbstractAnnealing Pb(Zr1−xTix)O3 (PZT) thin films in the hydrogen ambient can result in the unacceptable degradation of ferroelectric properties due to interaction of H2 forming gas with the ferroelectric materials. Since the understanding of this degradation mechanism is limited, this issue arouses a big problem for the application of PZT in high‐density non‐volatile ferroelectric random access memories (NVFRAM). In order to resolve this problem, we investigate Pt/PZT/Pt capacitors before and after H2 annealing at various temperatures. The capacitors lost their ferroelectric properties during hydrogen annealing. The measurements of polarization hysteresis loops and leakage currents suggest that there are different degradation mechanisms for the reduced PZT films. Although hydrogen induced degradation can be partially recovered by post‐annealing of the thin films in the O2 ambient, all the remanent polarizations after recovery are much smaller than their virgin values, which indicates the irreversible damage of the ferroelectricity during the forming gas annealing (FGA) process. In order to investigate the degradation mechanism, X‐ray diffraction was performed before and after FGA, and atomic force microscopy images were taken to observe the topograghy and microstructure changes. A conductive Pt‐coated piezoelectric force microscope probe was used as a mobile top electrode to check ferroelectric and piezoelectric properties within microregions of PZT films before and after FGA.
Structurally induced magnetization in a La2/3Sr4/3MnO4 superlattice
Authors: Shah Amish B. , Nelson‐Cheeseman Brittany B. , Subramanian Ganesh , Bhattacharya Anand , Spence John C. H. 
Published: March 2012

AbstractA structural transition has been observed in a digital superlattice of La2/3Sr4/3MnO4, which is correlated to a magnetization enhancement upon cooling the sample. These artificial superlattices were grown layer‐by‐layer using ozone‐assisted molecular beam epitaxy (MBE). Electron diffraction experiments show a phase transition below 150 K in nanopatches of the superlattice, which coincides with an enhanced magnetization starting below 110 K. Atomic scale electron energy loss spectroscopy (EELS) also shows changes in the Mn L2,3 and O K edges, which are related to valence, strain, and the atomic coordination within nanopatches.magnified image
Atomic resolution image and EELS showing variations of oxygen and lanthanum signature edges in a La2/3Sr4/3MnO4 supperlattice.
Threshold voltage of the EOSFET: Reference electrode and oxide–electrolyte interface
Authors: Fromherz Peter 
Published: March 2012

AbstractThe threshold voltage of the EOSFET is derived in close analogy to the common MOSFET, addressing the role of the reference electrode and of the oxide–electrolyte interface. It is shown that the reference electrode is characterized by the work function of its redox system, and that the oxide–electrolyte interface contributes by a change of the electrical polarization when it is formed from the free surfaces. The threshold of the EOSFET can be obtained from the threshold of a homologous MOSFET, if the change of the interfacial polarization is known, e.g., from a molecular dynamics simulation. Vice versa, a measured difference of the thresholds provides information on the change of the interfacial polarization. In sensor applications, changes of the interfacial polarization as well as of the electrical double layer must be taken into account.
Reactivities of hydroxyl and perhydroxyl radicals toward cytosine and thymine: A comparative study
Authors: Yadav Amarjeet , Mishra P. C. 
Published: March 2012

AbstractAs the hydroxyl (OH) and perhydroxyl (OOH) radicals are known to play important roles in biological systems, their reactions with cytosine and thymine were studied. Addition reactions of these radicals at different sites of cytosine and thymine, and hydrogen abstraction reactions by each of the two radicals from the different sites of the two molecules were studied at the B3LYP/6‐31G(d,p), B3LYP/AUG‐cc‐pVDZ and BHandHLYP/AUG‐cc‐pVDZ levels of density functional theory. Effect of solvation in aqueous media on the reactions was studied at all these levels of theory using single point energy calculations using the polarizable continuum model. The present study shows that whereas the OH radical would abstract H atoms from the various sites of cytosine and thymine efficiently, the OOH radical would have poor reactivity in this regard. The OH radical is also predicted to be much more reactive than the OOH radical with regard to addition reactions at the C5 and C6 sites of both thymine and cytosine, though the OOH radical is also predicted to have significant reactivity in this respect. © 2012 Wiley Periodicals, Inc.
Probing the electronic structure, magnetotropicity, and absorption spectra of benzene trapped by lanthanide monoxides, C6H6···LnO, using DFT methods
Authors: Tsipis Athanassios , Gkarmpounis Dimitrios 
Published: March 2012

AbstractThe electronic properties and chemical bonding of the C6H6:LnO (Bz:LnO) adducts have been investigated by density functional theory (DFT) calculations. Two types (I and II) of Bz:LnO adducts are formed upon trapping LnO by the benzene molecule. In type I, the benzene molecule is coordinated to the Ln atom in a η6‐coordination mode with the LnO perpendicular to the ring center, while in type II the LnO is inclined with respect to the ring plane. In type II adducts, the benzene molecule undergoes significant structural distortions adopting a boat conformation facing the Ln atom of LnO. In the bending conformation of benzene, the bond length equalization is lifted up with the 1,2‐ and 4,5‐double bonds shortened by 0.01 Å with respect to the CC double bond in the “free” benzene molecule while the remaining bonds are lengthened by about 0.04 Å, thus coordinated benzene exhibits a 1,4‐diene type π‐localization within the ring. The effect of adduct formation on the structural, spectroscopic, and magnetotropic properties of the coordinated benzene have been explored using electronic structure computational techniques. The main features of the Time Dependent DFT (TD‐DFT) simulated absorption spectra of the LnOs and C6H6:LnO adducts are analyzed and assignments of the electronic transitions are given. © 2012 Wiley Periodicals, Inc.