bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stereoselective Fluorination Alters the Geometry of a Cyclic Peptide: Exploration of Backbone‐Fluorinated Analogues of Unguisin A
Authors: Hu Xiang‐Guo , Thomas Donald S. , Griffith Renate , Hunter Luke 
Published: May 2014

AbstractNew methods for enhancing the efficiency of peptide cyclization, and for fine‐tuning the conformations of cyclic peptides, are valuable from a drug development perspective. Herein stereoselective fluorination is investigated as a new strategy for achieving these goals. Four vicinal difluorinated analogues of the natural cyclic heptapeptide unguisin A have been efficiently synthesized. The analogues are found to adopt dramatically different secondary structures, controlled by the fluorine stereochemistry.
Dissipative Particle Dynamics Simulation Study on Vesicles Self‐Assembled from Amphiphilic Hyperbranched Multiarm Copolymers
Authors: Wang Yuling , Li Bin , Jin Haibao , Zhou Yongfeng , Lu Zhongyuan , Yan Deyue 
Published: May 2014

AbstractHyperbranched multiarm copolymers (HMCs) have been shown to hold great potential as precursors in self‐assembly, and many impressive supramolecular structures have been prepared through the self‐assembly of HMCs in solution. However, theoretical studies on the corresponding self‐assembly mechanism have been greatly lagging behind. Herein, we report the self‐assembly of normal or reverse vesicles from amphiphilic HMCs by dissipative particle dynamics (DPD) simulation. The simulation disclosed both the self‐assembly mechanisms and dynamics of vesicles. It indicates that the self‐assembly of HMCs involves several steps, from randomly distributed unimolecular micelles to small spherical micelles, to membrane‐like micelles, to finally small vesicles. The membranes are formed through the direct aggregation and lateral fusion of small micelles, and the bending and closing of the membranes give rise to small vesicles. Finally, large and steady vesicles are formed through the fusion of small vesicles. In addition, the bilayer or monolayer molecular packing modes as well as the mircrophase separation behaviors of HMCs in normal or reverse vesicles have also been studied. These simulation results explore details that cannot be observed in the experiments to a certain degree, and have extended the understanding of the vesicular self‐assembly process of HMCs.
Lessons learned from the intrinsic subtypes of breast cancer in the quest for precision therapy
Authors: Norum J H , Andersen K , Sørlie T 
Published: May 2014

Abstract

Background
Wide variability in breast cancer, between patients and within each individual neoplasm, adds confounding complexity to the treatment of the disease. In clinical practice, hormone receptor status has been used to classify breast tumours and to guide treatment. Modern classification systems should take the wide tumour heterogeneity into account to improve patient outcome.

Methods
This article reviews the identification of the intrinsic molecular subtypes of breast cancer, their prognostic and therapeutic implications, and the impact of tumour heterogeneity on cancer progression and treatment. The possibility of functionally addressing tumour-specific characteristics in in vivo models to inform decisions for precision therapies is also discussed.

Results
Despite the robust breast tumour classification system provided by gene expression profiling, heterogeneity is also evident within these molecular portraits. A complicating factor in breast cancer classification is the process of selective clonality within developing neoplasms. Phenotypically and functionally distinct clones representing the intratumour heterogeneity might confuse molecular classification. Molecular portraits of the heterogeneous primary tumour might not necessarily reflect the subclone of cancer cells that causes the disease to relapse. Studies of reciprocal relationships between cancer cell subpopulations within developing tumours are therefore needed, and are possible only in genetically engineered mouse models or patient-derived xenograft models, in which the treatment-induced selection pressure on individual cell clones can be mimicked.

Conclusion
In the future, more refined classifications, based on integration of information at several molecular levels, are required to improve treatment guidelines. Large-scale translational research efforts paved the way for identification of the intrinsic subtypes, and are still fundamental for ensuring future progress in cancer care.
Improving the Stability and Catalyst Lifetime of the Halogenase RebH By Directed Evolution
Authors: Poor Catherine B. , Andorfer Mary C. , Lewis Jared C. 
Published: May 2014

AbstractWe previously reported that the halogenase RebH catalyzes selective halogenation of several heterocycles and carbocycles, but product yields were limited by enzyme instability. Here, we use directed evolution to engineer an RebH variant, 3‐LR, with a Topt over 5 °C higher than that of wild‐type, and 3‐LSR, with a Tm 18 °C higher than that of wild‐type. These enzymes provided significantly improved conversion (up to fourfold) for halogenation of tryptophan and several non‐natural substrates. This initial evolution of RebH not only provides improved enzymes for immediate synthetic applications, but also establishes a robust protocol for further halogenase evolution.
A Falling‐Film Microreactor for Enzymatic Oxidation of Glucose
Authors: Illner Sabine , Hofmann Christian , Löb Patrick , Kragl Udo 
Published: May 2014

AbstractMany oxidation processes require the presence of molecular oxygen in the reaction media. Reactors are needed that provide favorable conditions for the mass transfer between the gas and the liquid phase. In this study, two recent key technologies, microreactor technology and biotechnology, were combined to present an interesting alternative to conventional methods and open up excellent possibilities to intensify chemical processes in the field of fine chemicals. An enzyme‐catalyzed gas/liquid phase reaction in a falling‐film microreactor (FFMR) was examined for the first time. The test reaction was the oxidation of β‐D‐glucose to gluconic acid catalyzed by glucose oxidase (GOx). Various factors influencing the biotransformation, such as oxygen supply, temperature, enzyme concentration, and reaction time were investigated and compared to those in conventional batch systems. The most critical factor, the volumetric mass‐transfer coefficient for the efficient use of oxygen‐dependent enzymes, was determined by using the integrated online detection of dissolved oxygen in all systems. The extremely large surface‐to‐volume ratio of the FFMR facilitated the contact between the enzyme solution and the gaseous substrate. Hence, in a continuous bubble‐free FFMR system with a residence time of 25 seconds, a final conversion of up to 50 % in enzymatic oxidation was reached, whereas conversion in a conventional bubble column resulted in only 27 %. Finally, an option for scale‐up was shown through an enlarged version of the FFMR.
Palladium‐Nanoparticle‐Linked Organic Frameworks: Heterogeneous Recyclable Catalysts in Aqueous Medium
Authors: Prakash Sadasivan P. , Gopidas Karical R. 
Published: May 2014

Abstract4,4′‐Biphenylene‐bisdiazonium tetrafluoroborate and a palladium salt were reduced simultaneously to result in the formation of palladium atoms and 4,4′‐biphenylene biradicals. The palladium atoms underwent clustering forming palladium nanoparticles, whereas the 4,4′‐biphenylene biradicals underwent rapid addition reactions to other radicals and also to nanoparticle surfaces. The resulting product contains palladium nanoparticles covalently linked to an organic framework (PNOF). The effects of different reaction conditions upon metal content as well as on the morphology of the PNOF were studied. The PNOF structure was probed by different experimental techniques. The PNOFs were evaluated as heterogeneous recyclable catalyst in aqueous medium for reduction of 4‐nitrophenol and Suzuki coupling reactions. The catalyst exhibited high reactivity even in Suzuki couplings of aryl chlorides.
Annulation of Phenols: Catalytic Behavior of Conventional and 2 D Zeolites
Authors: Opanasenko Maksym V. , Shamzhy Mariya V. , Jo Changbum , Ryoo Ryong , Čejka Jiří 
Published: May 2014

AbstractCatalytic behavior of MFI zeolites differing in thickness of nanosheets and ordering was studied in annulation of phenols, and compared with 3 D zeolites BEA and MFI containing large or medium pores as well as with micro/mesoporous zeolite USY. The highest conversions of phenols studied were achieved over ordered hexagonally mesostructured zeolite with 1.7 nm wall size, followed by materials possessing 2.1 and 2.7 nm of nanosheets thickness. This corresponds to decreasing surface area of materials studied. The preferences of materials with zeolitic layers and high surface areas over bulky zeolites BEA and especially MFI in annulation of phenols is more prominent for substrates with larger kinetic diameters [phenol (0.66 nm)<1‐naphthol (0.80 nm)<2‐naphthol (0.89 nm)]. USY zeolite exhibited higher conversions (32, 6, 25 % for phenol, 1‐ and 2‐naphthol, respectively, after 300 min time on stream) than BEA (23, 6, 8 %) and MFI (13, 0, 0 %) not overcoming hexagonally mesostructured MFI (45, 36, 55 %).
mP‐BaP3: A New Phase from an Old Binary System
Authors: Dolyniuk Juli‐Anna , Kaseman Derrick C. , Sen Sabyasachi , Zhao Jing , Osterloh Frank E. , Kovnir Kirill 
Published: May 2014

AbstractA polyphosphide, mP‐BaP3, with a unique two‐dimensional phosphorus layer has been discovered and characterized. It crystallizes in the monoclinic space group P21/c with unit‐cell parameters a=6.486(1), b=7.710(1), c=8.172(2) Å; β=104.72(3)°; Z=4. Its phosphorus polyanion can be derived from the strong elongation of 2/3 of the PP bonds present in the layers of black phosphorus. The unit‐cell volume of the mP‐BaP3 phase is 1.4 % larger than the volume of another polymorph, mS‐BaP3, reported more than 40 years ago. The latter phase features the presence of one‐dimensional phosphorus chains separated by Ba atoms. The differences in the structures of the phosphorus fragments in both polymorphs of barium triphosphide result in large differences in both the thermal stability of these materials as well as in their properties as evidenced by DSC, 31P solid‐state MAS NMR, UV/Vis, and surface photovoltage spectroscopies, alongside quantum‐chemical calculations.
An Efficient AIE‐Active Blue‐Emitting Molecule by Incorporating Multifunctional Groups into Tetraphenylsilane
Authors: Tang Xiangyang , Yao Liang , Liu He , Shen Fangzhong , Zhang Shitong , Zhang Huanhuan , Lu Ping , Ma Yuguang 
Published: May 2014

AbstractA multifunctional AIE‐active molecule, CzPySiTPE, in which carbazole (Cz) and pyridine (Py) were attached to tetraphenylsilane to facilitate carrier injection has been designed and synthesized. Tetraphenylethene (TPE) was adopted to maintain efficient blue emission. Blue electroluminescent (EL) emission of CzPySiTPE was obtained with CIE coordinates of (0.16, 0.17) and an external quantum efficiency of 1.12 %.
Design, Synthesis, and Biological Evaluation of 1,3‐Diarylpropenones as Dual Inhibitors of HIV‐1 Reverse Transcriptase
Authors: Meleddu Rita , Cannas Valeria , Distinto Simona , Sarais Giorgia , Del Vecchio Claudia , Esposito Francesca , Bianco Giulia , Corona Angela , Cottiglia Filippo , Alcaro Stefano , Parolin Cristina , Artese Anna , Scalise Daniela , Fresta Massimo , Arridu Antonella , Ortuso Francesco , Maccioni Elias , Tramontano Enzo 
Published: May 2014

AbstractA small library of 1,3‐diarylpropenones was designed and synthesized as dual inhibitors of both HIV‐1 reverse transcriptase (RT) DNA polymerase (DP) and ribonuclease H (RNase H) associated functions. Compounds were assayed on these enzyme activities, which highlighted dual inhibition properties in the low‐micromolar range. Interestingly, mutations in the non‐nucleoside RT inhibitor binding pocket strongly affected RNase H inhibition by the propenone derivatives without decreasing their capacity to inhibit DP activity, which suggests long‐range RT structural effects. Biochemical and computational studies indicated that the propenone derivatives bind two different interdependent allosteric pockets.
Essential‐Oil Analysis of Irradiated Spices by Using Comprehensive Two‐Dimensional Gas Chromatography
Authors: Kirkin Celale , Mitrevski Blagoj , Gunes Gurbuz , Marriott Philip J. 
Published: May 2014

AbstractFour different spices were packaged either under 100 % nitrogen or using ambient air, and then gamma‐irradiated at different doses. The essential oils of the original spices and of those irradiated were obtained by hydrodistillation. Changes to the essential‐oil compositions due to irradiation and effects of packaging were detected and compared by using comprehensive two‐dimensional gas chromatography (GC×GC). The use of GC×GC provided better separation and more reliable results. It enabled ready detection of some peaks that coeluted with other peaks in the first‐dimension column (1D). Differences in detected peaks were observed after irradiation of samples packaged under ambient air, with additional peak(s) noted. Two peaks appeared after irradiation of aerobically packaged rosemary, black pepper and thyme, and one peak increased in relative abundance in the samples. No changes in these three peaks were noted after irradiation of samples packaged under 100 % N2. These three essential‐oil components were identified by using GC×GC quadrupole time‐of‐flight mass spectrometry (Q‐TOFMS). The changes after irradiation were mainly due to packaging type, and no effect of the irradiation dose was observed in the study.
Cobalt Dopant with Deep Redox Potential for Organometal Halide Hybrid Solar Cells
Authors: Koh Teck Ming , Dharani Sabba , Li Hairong , Prabhakar Rajiv Ramanujam , Mathews Nripan , Grimsdale Andrew C. , Mhaisalkar Subodh G. 
Published: May 2014

AbstractIn this work, we report a new cobalt(III) complex, tris[2‐(1H‐pyrazol‐1‐yl)pyrimidine]cobalt(III) tris[bis(trifluoromethylsulfonyl)imide] (MY11), with deep redox potential (1.27 V vs NHE) as dopant for 2,2′,7,7′‐tetrakis‐(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene (spiro‐OMeTAD). This dopant possesses, to the best of our knowledge, the deepest redox potential among all cobalt‐based dopants used in solar cell applications, allowing it to dope a wide range of hole‐conductors. We demonstrate the tuning of redox potential of the Co dopant by incorporating pyrimidine moiety in the ligand. We characterize the optical and electrochemical properties of the newly synthesized dopant and show impressive spiro‐to‐spiro+ conversion. Lastly, we fabricate high efficiency perovskite‐based solar cells using MY11 as dopant for molecular hole‐conductor, spiro‐OMeTAD, to reveal the impact of this dopant in photovoltaic performance. An overall power conversion efficiency of 12 % is achieved using MY11 as p‐type dopant to spiro‐OMeTAD.
Unique mitochondrialDNAlineages in Irish stickleback populations: cryptic refugium or rapid recolonization?
Authors: Ravinet Mark , Harrod Chris , Eizaguirre Christophe , Prodöhl Paulo A. 
Published: May 2014

AbstractRepeated recolonization of freshwater environments following Pleistocene glaciations has played a major role in the evolution and adaptation of anadromous taxa. Located at the western fringe of Europe, Ireland and Britain were likely recolonized rapidly by anadromous fishes from the North Atlantic following the last glacial maximum (LGM). While the presence of unique mitochondrial haplotypes in Ireland suggests that a cryptic northern refugium may have played a role in recolonization, no explicit test of this hypothesis has been conducted. The three‐spined stickleback is native and ubiquitous to aquatic ecosystems throughout Ireland, making it an excellent model species with which to examine the biogeographical history of anadromous fishes in the region. We used mitochondrial and microsatellite markers to examine the presence of divergent evolutionary lineages and to assess broad‐scale patterns of geographical clustering among postglacially isolated populations. Our results confirm that Ireland is a region of secondary contact for divergent mitochondrial lineages and that endemic haplotypes occur in populations in Central and Southern Ireland. To test whether a putative Irish lineage arose from a cryptic Irish refugium, we used approximate Bayesian computation (ABC). However, we found no support for this hypothesis. Instead, the Irish lineage likely diverged from the European lineage as a result of postglacial isolation of freshwater populations by rising sea levels. These findings emphasize the need to rigorously test biogeographical hypothesis and contribute further evidence that postglacial processes may have shaped genetic diversity in temperate fauna.
Prognostic value of circulating tumor cells with podoplanin expression in patients with locally advanced or metastatic head and neck squamous cell carcinoma
Authors: Hsieh Jason Chia‐Hsun , Lin Hung‐Chih , Huang Chi‐Ya , Hsu Hsung‐Ling , Wu Tyler Min‐Hsien , Lee Chia‐Lin , Chen Min‐Chi , Wang Hung‐Ming , Tseng Ching‐Ping 
Published: May 2014

AbstractBackgroundPodoplanin (PDPN) is a prognostic factor for head and neck squamous cell carcinoma (HNSCC). However, PDPN expression in circulating tumor cells (CTCs) and its prognostic value are not clear.MethodsThe PowerMag system was used to enumerate CTCs from 53 patients with HNSCC prechemotherapy and 61 healthy donors. PDPN expression was determined by immunofluorescence staining. Results were correlated with clinicopathological parameters and clinical outcome, such as patient survival by receiver operating characteristic (ROC) and univariate and multivariate analyses.ResultsPDPN was expressed in a subset of CTCs. Both EpCAM‐positive CTC and PDPN‐positive CTC counts were statistically different between the disease and nondisease groups (p < .0001) with no prognostic value. After a median follow‐up of 10.5 months (range, 6.6–18.5 months), the PDPN‐positive/EpCAM‐positive CTC ratio >20% was a significant prognostic factor for death within 6 months (p = .011) and was correlated with poor progression‐free survival (p = .016) and overall survival (p = .015).ConclusionPDPN‐positive/EpCAM‐positive CTC ratio is a prognostic factor and defining the ratio in patients with HNSCC might be valuable to clinical management. © 2014 Wiley Periodicals, Inc. Head Neck 37: 1448–1455, 2015
Low‐frequency modulation and trend of the relationship between ENSO and precipitation along the northern to centre Peruvian Pacific coast
Authors: Bourrel Luc , Rau Pedro , Dewitte Boris , Labat David , Lavado Waldo , Coutaud Aude , Vera Andrea , Alvarado Abigail , Ordoñez Julio 
Published: May 2014

AbstractThe relationship between El Niño Southern Oscillation (ENSO) and precipitation along the Peruvian Pacific coast is investigated over 1964–2011 on the basis of a variety of indices accounting for the different types of El Niño events and atmospheric and oceanographic manifestations of the interannual variability in the tropical Pacific. We show the existence of fluctuations in the ENSO/precipitation relationship at decadal timescales that are associated with the ENSO property changes over the recent decades. Several indices are considered in order to discriminate the influence of the two types of El Niño, namely, the eastern Pacific El Niño and the central Pacific El Niño, as well as the influence of large‐scale atmospheric variability associated to the Madden and Julian Oscillation, and of regional oceanic conditions.Three main periods are identified that correspond to the interleave periods between the main climatic transitions over 1964–2011, i.e. the shifts of the 1970s and the 2000s, over which ENSO experiences significant changes in its characteristics. We show that the relationship between ENSO and precipitation along the western coast of Peru has experienced significant decadal change. Whereas El Niño events before 2000 lead to increased precipitation, in the 2000s, ENSO is associated to drier conditions. This is due to the change in the main ENSO pattern after 2000 that is associated to cooler oceanic conditions off Peru during warm events (i.e. central Pacific El Niño). Our analysis also indicates that the two extreme El Niño events of 1982/1983 and 1997/1998 have overshadowed actual trends in the relationship between interannual variability in the tropical Pacific and precipitation along the coast of Peru. Overall, our study stresses on the complexity of the hydrological cycle on the western side of the Andes with regard to its relationship with the interannual to decadal variability in the tropical Pacific. Copyright © 2014 John Wiley & Sons, Ltd.
Does the Feminisation of Agricultural Labour Empower Women? Insights from Female Labour Contractors and Workers in Northwest Syria
Authors: Abdelali‐Martini Malika , Dey de Pryck Jennie 
Published: May 2014

AbstractWith major socio‐economic changes in the Middle East and North Africa spurring men's exit from agriculture, women now represent over 60 per cent of the agricultural workforce in several countries. Drawing on original field research, this paper analyses the emergence of female agricultural labour contractors and female wage labour groups in north‐west Syria and compares the outcomes for the contractors' and labourers' empowerment with regard to four dimensions of power or agency: power within, power to, power over and power with. An evolving but delicate balance between continuity and transformation has permitted modest gains in women's empowerment without challenging intrahousehold gender power relations. Copyright © 2014 John Wiley & Sons, Ltd.
A New Insight into the Mechanism of 1,3‐Dienes Cationic Polymerization III: Polymerization of 1,3‐Pentadiene with CF3COOD/TiCl4 Initiating System: Chain‐Ends Structure and Kinetics
Authors: Rozentsvet Victor A. , Kozlov Valery G. , Korovina Nelly A. , Novakov Ivan A. , Kostjuk Sergei V. 
Published: May 2014

A novel method for the investigation of the chain‐end structure of poly(1,3‐pentadiene)s synthesized using the CF3COOD/TiCl4 initiating system is developed. It is shown for the first time that the content of trans‐1,2‐structures in the first monomer unit is considerably higher than the content of trans‐1,4‐structures, whereas the content of trans‐1,4‐units is substantially higher than trans‐1,2‐units for the polymer chain as a whole. Another important observation is that chain transfer to monomer is significant even at the earlier stages of the 1,3‐pentadiene polymerization (after 1 s of reaction). The very low functionality at the ω‐end (Fn
(Cl) < 0.15) confirms the intensive chain transfer to monomer. This method is also applied for the estimation of the concentration of active species and the rate constant for propagation (k
p) for the cationic polymerization of 1,3‐pentadiene using the CF3COOD/TiCl4 initiating system: rate constants for propagation, k
p, of 1.5 × 103 and 3.3 × 103 L mol−1 min−1 are determined for 1,3‐pentadiene polymerization at 20 and –78 °C, respectively.
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Hollow Microporous Organic Capsules Loaded with Highly Dispersed Pt Nanoparticles for Catalytic Applications
Authors: Yang Xinjia , Song Kunpeng , Tan Liangxiao , Hussain Irshad , Li Tao , Tan Bien 
Published: May 2014

Hollow microporous organic capsules embedded with small and monodisperse Pt nanoparticles (NPs) are designed and synthesized successfully. The transmission electron microscopy (TEM) results show that the materials with amine groups and a microporous structure act as a better support for obtaining highly dispersed Pt NPs in the micropores. After several successive catalytic reactions, the TEM and porous structure of the heterogeneous catalysts do not show any observable changes. The heterogeneous catalysts are highly stable in air and no decrease in activity is observed after the catalyst is exposed to air for several days. These heterogeneous catalysts exhibit excellent catalytic activity and recyclability potential, combined with mild conditions, and the possibility of using alcoholic reaction media for the nitroaromatic hydrogenation.
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