bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tuning the Electronics of Phosphorescent, Amide‐Functionalized, Cyclometalated IrIII Complexes: Syntheses, Structures, Spectroscopy and Theoretical Studies
Authors: Routledge Jack D. , Hallett Andrew J. , Platts James A. , Horton Peter N. , Coles Simon J. , Pope Simon J. A. 
Published: August 2012

AbstractIridium(III) complexes were synthesized with the general form [Ir(L1–6)2(bpy)]PF6 (bpy = 2,2′‐bipyridine), where ligands (LH1–6) are based on the N‐functionalization of 2‐phenyl‐N‐aryl/alkyl‐quinoline‐4‐carboxamides. Single crystal X‐ray diffraction studies were undertaken on two complexes, which show that each adopts a distorted octahedral coordination geometry with retention of the expected trans‐N, cis‐C arrangement of the cyclometalated ligands. Electrochemical studies confirmed the subtle perturbing of theIrIII/IV redox couple as a function of ligand structure. Scalar relativistic DFT studies provided qualitative descriptions of the HOMO and LUMO energy levels of the six complexes. The calculated HOMO is generally located over the Ir(5d) centre (about 45 %) and the amide‐substituted 2‐phenylquinoline ligand, whilst the LUMO is localized over the ancillary 2,2′‐bipyridine ligand. Similar calculations for [Ir(L6)2(bpy)]PF6 revealed a different HOMO depiction with locale on the pendant chromophores. A companion calculation, using an alternative relativistic approach (i.e. incorporating spin–orbit coupling effects) conducted on a simplified model compound, provided HOMO/LUMO depictions that are essentially identical to the non‐relativistic calculation, which predicts long‐lived phosphorescent emission from the HOMO–LUMO transition. Luminescence studies showed the predictable and tunable phosphorescent emission wavelengths between 585–627 nm. The experimental and theoretical studies suggest that the electronic nature of the pendant amide substituent influences the energy of the emitting state – the strongly electron‐withdrawing groups bathochromically shift the luminescence wavelength.
Synthesis, Structure and Properties of a Five‐Coordinate Oxophosphorus(V) meso‐Triphenylcorrole
Authors: Ghosh Avijit , Lee Way‐Zen , Ravikanth Mangalampalli 
Published: August 2012

AbstractTreatment of six‐coordinate (5,10,15‐triphenylcorrole)dihydroxyphosphorus(V) [P(TPC)(OH)2] with trifluoroacetic acid (TFA) in CH2Cl2 for 30 min at room temperature followed by recrystallization gave stable five‐coordinate (5,10,15‐triphenylcorrole)oxophosphorus(V) [P(TPC)O] in quantitative yield. The formation of [P(TPC)O] from [P(TPC)(OH)2] in the presence of TFA was also monitored by NMR, absorption and fluorescence spectroscopic titration studies. The structure of the isolated [P(TPC)O] was confirmed by X‐ray crystallography. In [P(TPC)O], the corrole ring is distorted, and the PV ion is displaced by 0.456 Å from the N4 plane towards the axial oxygen atom. This is unlike six‐coordinate (5,10,15‐triphenylcorrole)dimethoxyphosphorus(V) [P(TPC)(OCH3)2], in which the PV ion lies in the porphyrin plane. NMR, absorption and fluorescence spectroscopy and electrochemical studies indicate that [P(TPC)O] exhibits interesting and distinct properties, which differ from the six‐coordinate [P(TPC)(OCH3)2]. Attempts to reduce the PV complex [P(TPC)O] to its corresponding PIII complex by treating it with LiAlH4 resulted in the formation of six‐coordinate (5,10,15‐triphenylcorrole)dihydridophosphorus(V) [P(TPC)H2].
Structures and Antibacterial Activities of Minor Dolabellanes from the Brown Alga Dilophus spiralis
Authors: Ioannou Efstathia , Quesada Antonio , Rahman M. Mukhlesur , Gibbons Simon , Vagias Constantinos , Roussis Vassilios 
Published: August 2012

AbstractThirteen new minor diterpenes featuring the dolabellane skeleton (1–13) were isolated from the organic extracts of the brown alga Dilophus spiralis, collected in Elafonissos Island. The structures and relative configurations of the isolated natural products were elucidated on the basis of extensive analyses of their spectroscopic data (NMR, MS, IR). The absolute configuration of 1 was determined by using the modified Mosher's method, whereas the structure of 2 was confirmed by single‐crystal X‐ray diffraction analysis. The antibacterial activities of metabolites 1–9 and 13 were evaluated against six strains of Staphylococcus aureus, including multidrug‐ and methicillin‐resistant variants. Compounds 1 and 4 exhibited noteworthy levels of activity with MIC values in the range of 2–8 μg/mL.
Synthesis of SHIP1‐Activating Analogs of the Sponge Meroterpenoid Pelorol
Authors: Meimetis Labros G. , Nodwell Matt , Yang Lu , Wang Xiaoxia , Wu Joyce , Harwig Curtis , Stenton Grant R. , Mackenzie Lloyd F. , MacRury Thomas , Patrick Brian O. , Ming‐Lum Andrew , Ong Christopher J. , Krystal Gerald , Mui Alice L. ‐F. , Andersen Raymond J. 
Published: August 2012

AbstractTwo biomimetic approaches have been used to synthesize analogs of the SHIP1‐activating sponge meroterpenoid pelorol (1). One approach started from the chiral pool plant natural product sclareolide, which has the same absolute configuration as pelorol. The second approach utilized an enantioselective polyene cyclization to efficiently access both absolute configurations of the pelorol meroterpenoid skeleton and to prepare A‐ring functionalized compounds. Selected analogs have been evaluated for water solubility and biological activity. It was found that the undesirable catechol and ester functionalities in 1 could be removed to give MN100 (3), without a decrease in SHIP1‐activating ability. A further refinement led to the resorcinol analog 18, which is the most effective SHIP1‐activating pelorol analog made to date. The HCl salt of ent‐28, a C‐3 amino analog of 18, is about 500,000‐fold more soluble in water than MN100 (3). (±)‐28·HCl activates SHIP1 in vitro, inhibits Akt phosphorylation in stimulated MOLT‐4 (SHIP+) cells, and is active in a dose‐dependent manner in a mouse model of inflammation when administered by oral gavage (ED50 ≈ 0.1 mg/kg). Pelorol analogs ent‐28 or (±)‐28 are promising chemical tools for further preclinical in vivo evaluation of the potential of SHIP1 activators as therapeutics for treating hematopoietic diseases involving aberrant activation of PI3K cell signaling.
Synthesis, Properties and Applications of Biphenyl Functionalized 9,9‐Bis(4‐diphenylaminophenyl)fluorenes as Bifunctional Materials for Organic Electroluminescent Devices
Authors: Thangthong A‐monrat , Prachumrak Narid , Namuangruk Supawadee , Jungsuttiwong Siriporn , Keawin Tinnagon , Sudyoadsuk Taweesak , Promarak Vinich 
Published: August 2012

AbstractFour new bifunctional materials, namely BPTF, CBPTF, CMBPTF and BPVTF, having 9,9‐bis(4‐diphenylaminophenyl)fluorene as a molecular platform and biphenyl derivatives as end‐capping substituents were synthesized and characterized. Their optimized structures revealed that both triphenylamine moieties at the C‐9 position of the fluorene ring generated a bulky molecular structure. These molecules showed strong blue emission in both solution and in the solid state, and were thermally stable amorphous materials with glass transition temperatures up to 207 °C. The abilities of these materials to act as blue‐light‐emitting materials for blue OLEDs and hole‐transporting materials for green OLEDs in terms of device performance and thermal properties were superior to commonly used N,N′‐diphenyl‐N,N′‐bis(1‐naphthyl)‐(1,1′‐biphenyl)‐4,4′‐diamine (NPB). Efficient, and bright nondoped deep‐blue and Alq3‐based green OLEDs with maximum luminance efficiencies and CIE coordinates of 2.48 cd A–1 and x = 0.15 and y = 0.07, and 4.40 cd A–1 and x = 0.28 and y = 0.52 were achieved, respectively, with BPTF having two biphenyl substituents as active layers. Both devices showed low turn‐on voltages of 3.1 and 2.8 V, respectively. Notably, the color purities of these deep‐blue and green devices were close to the National Television Standards Committee blue (CIE coordinates of x = 0.14 and y = 0.08) and green (CIE coordinates of x = 0.26 and y = 0.65) standards.
Aluminum induces oxidative burst, cell wall NADH peroxidase activity, and DNA damage in root cells of Allium cepa L
Authors: Achary V. Mohan M. , Parinandi Narasimham L. , Panda Brahma B. 
Published: August 2012

AbstractPlants under stress incur an oxidative burst that involves a rapid and transient overproduction of reactive oxygen species (ROS: O2•−, H2O2, •OH). We hypothesized that aluminum (Al), an established soil pollutant that causes plant stress, would induce an oxidative burst through the activation of cell wall‐NADH peroxidase (NADH‐PX) and/or plasma membrane‐associated NADPH oxidase (NADPH‐OX), leading to DNA damage in the root cells of Allium cepa L. Growing roots of A. cepa were treated with Al3+ (800 μM of AlCl3) for 3 or 6 hr without or with the pretreatment of inhibitors specific to NADH‐PX and NADPH‐OX for 2 hr. At the end of the treatment, the extent of ROS generation, cell death, and DNA damage were determined. The cell wall‐bound protein (CWP) fractions extracted from the untreated control and the Al‐treated roots under the aforementioned experimental conditions were also subjected to in vitro studies, which measured the extent of activation of peroxidase/oxidase, generation of •OH, and DNA damage. Overall, the present study demonstrates that the cell wall‐bound NADH‐PX contributes to the Al‐induced oxidative burst through the generation of ROS that lead to cell death and DNA damage in the root cells of A. cepa. Furthermore, the in vitro studies revealed that the CWP fraction by itself caused DNA damage in the presence of NADH, supporting a role for NADH‐PX in the stress response. Altogether, this study underscores the crucial function of the cell wall‐bound NADH‐PX in the oxidative burst‐mediated cell death and DNA damage in plants under Al stress. Environ. Mol. Mutagen., 2012. © 2012 Wiley Periodicals, Inc.
Channel network extent in the context of historical land use, flow generation processes, and landscape evolution in the North Carolina Piedmont
Authors: Jefferson Anne J. , McGee Ralph W. 
Published: August 2012

ABSTRACTIntensive agricultural land use in the 18th to early 20th centuries on the southeastern Piedmont resulted in substantial soil erosion and gully development. Today, many historically farmed areas have been abandoned and afforested, and such landscapes are an opportunity to study channel network recovery from disturbance by gullying. Channel initiation mapping, watershed area–slope relationships, and field monitoring of flow generation processes are used to identify channel network extent and place it in hydrologic, historical and landscape evolution context. In six study areas in the North Carolina Piedmont, 100 channel heads were mapped in fully‐forested watersheds, revealing a channel initiation relationship of 380 = AS1.27, whereAis contributing area (m2) andSis local slope (m/m). Flow in these channels is generated by subsurface and overland flow. The measured relative slope exponent is lower than expected based on literature values of ~2 for forested watersheds with subsurface and overland flow, suggesting that the channel network extent may reflect a former hydrological regime. However, geomorphic evidence of recovery in channel heads within fully forested watersheds is greater than those with present day pasture. Present day channel heads lie within hollows or downslope of unchanneled valleys, which may be remnants of historical gullies, and area–slope relationships provide evidence of colluvial aggradation within the valleys. Channel network extent appears to be sensitive to land use change, with recovery beginning within decades of afforestation. Channel initiation mapping and area–slope relationships are shown to be useful tools for interpreting geomorphic effects of land use change. Copyright © 2012 John Wiley & Sons, Ltd.
Combined effects of temperature and pyriproxyfen stress in a full life-cycle test with Chironomus riparius (Insecta)
Authors: Tassou Koffi Tcha , Schulz Ralf 
Published: August 2012

Abstract
Traditional risk assessment guidelines employ acute or chronic toxicity tests for a maximum of one generation of organisms. These tests are usually performed in the laboratory at a constant standard temperature, although in the field organisms may experience different temperatures, which may be a source of additional stress. Climate change–related temperature shifts may have serious impacts on ectotherm populations that are key components of the aquatic food chains, particularly in combination with the exposure of pollutants affecting their development. Here, a chronic full life-cycle test with Chironomus riparius from the first-instar larvae in the parental (P) generation until emergence in the subsequent F1 generation was conducted at different temperatures (16 and 24°C), testing the effect of the insect growth regulator pyriproxyfen at 1, 3, 10, 30, and 100 µg/L. The emergence ratios were significantly affected by the interaction of temperature, chemical treatment, and generation, showing that, at lower temperatures, the negative effects of pyriproxyfen exposure were significantly greater in the F1 generation than in the P generation. The development rate showed that the effects of the interactions were significant in the F1 generation, underscoring the importance of extended exposure as a useful amendment to the risk assessment of those agrochemicals potentially influencing developmental and reproductive parameters in intact organisms. Moreover, results demonstrated that any difference from the standard temperature of 20°C might result in additional stress, leading to disruption of biological functions in C. riparius, highlighting the interaction among different global climate change-related variables. Environ. Toxicol. Chem. 2012; 31: 2384–2390. © 2012 SETAC
Accumulation of polychlorinated biphenyls from contaminated sediment by Atlantic cod (Gadus morhua): Direct accumulation from resuspended sediment and dietary accumulation via the polychaete Nereis virens
Authors: Ruus Anders , Daae Ingrid Aarre , Hylland Ketil 
Published: August 2012

Abstract
Bioaccumulation of sediment-associated polychlorinated biphenyls (PCBs) was examined in Atlantic cod (Gadus morhua) through direct diffusion from the sediment (via the water phase) and through the food chain (dietary exposure). To facilitate direct accumulation from the sediment, it was continuously resuspended. To study the dietary bioaccumulation of PCBs, cod were fed benthic polychaetes (Nereis virens) previously exposed to test sediments, which were naturally polluted sediments from the inner Oslofjord (Norway). Both exposure experiments had a duration of 129 d. Furthermore, the role of sediments as a source of PCBs accumulated in Oslofjord cod was elucidated, using results from environmental monitoring as a reference. Generally, the results suggest that the contaminated sediments of the inner Oslofjord are an important source of legacy PCBs for accumulation in resident cod, although additional contributions may also be important. Crude estimates of assimilation efficiency of ingested PCBs (through diet) were found to be 30 to 50%; the highest was for the lower chlorinated congeners (PCB-28 and -52). Challenges for applying trophic magnification factors for determining biomagnification in laboratory experiments, in terms of preventive environmental safety, are indicated. The results provide useful information for parameterization of models describing the behavior of hydrophobic persistent contaminants in the foodweb of the Oslofjord and elsewhere. Environ. Toxicol. Chem. 2012; 31: 2472–2481. © 2012 SETAC
OpenWSN: a standards‐based low‐power wireless development environment
Authors: Watteyne Thomas , Vilajosana Xavier , Kerkez Branko , Chraim Fabien , Weekly Kevin , Wang Qin , Glaser Steven , Pister Kris 
Published: August 2012

ABSTRACTThe OpenWSN project is an open‐source implementation of a fully standards‐based protocol stack for capillary networks, rooted in the new IEEE802.15.4e Time Synchronized Channel Hopping standard. IEEE802.15.4e, coupled with Internet of Things standards, such as 6LoWPAN, RPL and CoAP, enables ultra‐low‐power and highly reliable mesh networks, which are fully integrated into the Internet. The resulting protocol stack will be cornerstone to the upcoming machine‐to‐machine revolution.This article gives an overview of the protocol stack, as well as key integration details and the platforms and tools developed around it. The pure‐C OpenWSN stack was ported to four off‐the‐shelf platforms representative of hardware currently used, from older 16‐bit microcontroller to state‐of‐the‐art 32‐bit Cortex‐M architectures. The tools developed around the low‐power mesh networks include visualisation and debugging software, a simulator to mimic OpenWSN networks on a PC, and the environment needed to connect those networks to the Internet.Experimental results presented in this article include a network where motes operate at an average radio duty cycle well below 0.1% and an average current draw of 68  μA on off‐the‐shelf hardware. These ultra‐low‐power requirements enable a range of applications, with motes perpetually powered by micro‐scavenging devices. OpenWSN is, to the best of our knowledge, the first open‐source implementation of the IEEE802.15.4e standard. Copyright © 2012 John Wiley & Sons, Ltd.
Influence of carbon nanotubes on fire behaviour and aerosol emitted during combustion of thermoplastics
Authors: Chivas‐Joly C. , Motzkus C. , Guillaume E. , Ducourtieux S. , Saragoza L. , Lesenechal D. , Lopez‐Cuesta J‐M. , Longuet C. , Sonnier R. , Minisini B. 
Published: August 2012

ABSTRACTCarbon nanotube‐based poly(methyl methacrylate) and polyamide‐6 nanocomposites have been investigated using various techniques within the framework of the NANOFEU project. Scanning transmission electron microscopy was used to characterize morphologies of composites, while fire properties were studied using cone calorimeter and pyrolysis combustion flow microcalorimeter. The study focused particularly on composition and microstructure of gaseous and aerosol products. Morphology of ultrafine particles released from the combustion of nanocomposites was studied using cascade impactor and atomic force microscopy. Fire behaviour has been interpreted in relation with the degradation mechanisms specifically induced by the presence of carbon nanotubes. Copyright © 2012 John Wiley & Sons, Ltd.
Nutritional‐rich and stress‐tolerant crops by saccharopine pathway manipulation
Authors: Arruda Paulo , Neshich Izabella Pena 
Published: August 2012

AbstractLysine is a limiting essential amino acid in cereals, a major food source for humans and animals. Although cereals can synthesize lysine from aspartate, the pathway is feedback regulated in a manner that restricts lysine accumulation. Another step that restricts lysine accumulation in seeds is the saccharopine pathway for lysine catabolism. This pathway converts lysine to α‐aminoadipic‐δ‐semialdehyde (AASA) by the bifunctional enzyme lysine‐ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH). Then, AASA is converted to aminoadipic acid (AAA) by α‐aminoadipic‐δ‐semialdehyde dehydrogenase (AASADH). The downregulation of LKR/SDH in seeds results in the overaccumulation of free lysine to levels that meet human nutritional requirements. However, the saccharopine pathway is also involved in stress response in plants, animals, and bacteria. In these organisms, the gene encoding LKR/SDH is upregulated under osmotic, salt, and oxidative stress conditions. The role of the saccharopine pathway in stress response is not well understood, but the overexpression of AASADH results in stress‐tolerant plants and animal cells. The saccharopine pathway may thus act either by producing osmolytes, such as pipecolic acid and proline, or by signaling compounds that regulate stress‐response genes. In this review, we discuss the potential use of the saccharopine pathway to engineer nutritional‐rich and stress‐tolerant crops.
Glutathione peroxidase 1 activity dictates the sensitivity of glioblastoma cells to oxidative stress
Authors: Dokic Ivana , Hartmann Christian , Herold‐Mende Christel , Régnier‐Vigouroux Anne 
Published: August 2012

AbstractThe high intratumoral and intertumoral heterogeneity of glioblastoma (GBM) leads to resistance to different therapies, and hence, selecting an effective therapy is very challenging. We hypothesized that the antioxidant enzyme status is a significant feature of GBM heterogeneity. The most important reactive oxygen/nitrogen species (ROS/RNS) detoxification mechanisms include superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPx). Expression and activity of these enzymes and the cellular response to induced oxidative stress were systematically analyzed and compared between GBM cells and nontransformed glial cells of both human and murine origin. Regardless of cell type or species, all tested cells expressed similar amount of catalase and MnSOD. All except one, GBM cell lines exhibited a deficiency in GPx1 expression and activity. Analysis of GBM tissue sections indicated a heterogeneous profile of weak to moderate expression of GPx1 in tumor cells. GPx1 deficiency led to an accumulation of ROS/RNS and subsequent death of GBM cells after induction of oxidative stress. Astrocytes, microglia/macrophages, and glioma stem cell lines expressed active GPx1 and resisted ROS/RNS‐mediated cell death. Pharmacological inhibition or siRNA silencing of GPx1 partially reverted this resistance in astrocytes, indicating the contribution of various antioxidant molecules besides GPx1. The GPx1‐expressing GBM cell line on the contrary, became extremely sensitive to oxidative stress after GPx1 inhibition. Altogether, these results highlight GPx1 as a crucial element over other antioxidant enzymes for oxidative stress regulation in GBM cells. Mapping the antioxidant enzyme status of GBM may prove to be a useful tool for personalized ROS/RNS inducing therapies. © 2012 Wiley Periodicals, Inc.
Induction of neuronal phenotypes from NG2+ glial progenitors by inhibiting epidermal growth factor receptor in mouse spinal cord injury
Authors: Ju Peijun , Zhang Si , Yeap Yeeshan , Feng Zhiwei 
Published: August 2012

AbstractBesides neural stem cells, some glial cells, such as GFAP+ cells, radial glia, and oligodendrocyte progenitor cells can produce neuronal cells. Attractively, NG2+ glial progenitors exhibit lineage plasticity, and they rapidly proliferate and differentiate in response to central nervous system (CNS) injuries. These attributes of NG2+ glial progenitors make them a promising source of neurons. However, the potential of neuronal regeneration from NG2+ glial progenitors in CNS pathologies remains to be investigated. In this study, we showed that antagonizing epidermal growth factor receptor (EGFR) function with EGFR inhibitor caused a significant number of proliferative NG2+ glial progenitors to acquire neuronal phenotypes in contusive spinal cord injury (SCI), which presumably led to an accumulation of newly generated neurons and contributed to the improved neural behavioral performance of animals. In addition, the neuronal differentiation of glial progenitors induced by EGFR inhibitor was further confirmed with two different cell lines either in vitro or through ex vivo transplantation experiment. The inhibition of EGFR signaling pathway under the gliogenic conditions could induce these cells to acquire neuronal phenotypes. Furthermore, we find that the Ras‐ERK axis played a key role in neuronal differentiation of NG2+ glial progenitors upon EGFR inhibition. Taken together, our studies suggest that the EGFR inhibitor could promote neurogenesis post SCI, mainly from the NG2+ glial progenitors. These findings support the possibility of evoking endogenous neuronal replacement from NG2+ glial progenitors and suggest that EGFR inhibition may be beneficial to CNS trauma. © 2012 Wiley Periodicals, Inc.