Search

The bimolecular recombination characteristics of conjugated polymer poly[(4,4′-bis(2-ethylhexyl)dithieno[3,2-b:2′,3′-d]silole)-2,6-diyl-alt-(2,5-bis 3-tetradecylthiophen-2-yl thiazolo 5,4-d thiazole)-2,5diyl] (PDTSiTTz) blended with the fullerene series PC60BM, ICMA, ICBA, and ICTA have been investigated using microsecond and femtosecond transient absorption spectroscopy, in conjunction with electroluminescence measurements and ambient photoemission spectroscopy. The non-Langevin polymer PDTSiTTz allows an inspection of intrinsic bimolecular recombination rates uninhibited by diffusion, while the low oscillator strengths of fullerenes allow polymer features to dominate, and we compare our results to those of the well-known polymer Si-PCPDTBT. Using μs-TAS, we have shown that the trap-limited decay dynamics of the PDTSiTTz polaron becomes progressively slower across the fullerene series, while those of Si-PCPDTBT are invariant. Electroluminescence measurements showed an unusual double peak in pristine PDTSiTTz, attributed to a low energy intragap charge transfer state, likely interchain in nature. Furthermore, while the pristine PDTSiTTz showed a broad, low-intensity density of states, the ICBA and ICTA blends presented a virtually identical DOS to Si-PCPDTBT and its blends. This has been attributed to a shift from a delocalized, interchain highest occupied molecular orbital (HOMO) in the pristine material to a dithienosilole-centered HOMO in the blends, likely a result of the bulky fullerenes increasing interchain separation. This HOMO localization had a side effect of progressively shifting the polymer HOMO to shallower energies, which was correlated with the observed decrease in bimolecular recombination rate and increased “trap” depth. However, since the density of tail states remained the same, this suggests that the traditional viewpoint of “trapping” being dominated by tail states may not encompass the full picture and that the breadth of the DOS may also have a strong influence on bimolecular recombination.

Organo-lead halide perovskite solar cells represent a revolutionary shift in solar photovoltaics, introducing relatively soft defect containing semiconductors as materials with excellent charge collection for both electrons and holes. Although they are based on the nominally simple cubic perovskite structure, these compounds are in fact very complex. For example, in (CH3NH3)PbI3 the dynamics and ensuing structural fluctuations associated with the (CH3NH3)+ ions and the interplay with the electronic properties are still not fully understood, despite extensive study. Here, using ab-initio calculations, we show that at room and higher temperature, the rotation of CH3NH3 molecules can be viewed as effectively giving local structures that are cubic and tetragonal like from the point of view of the PbI3 framework, though in fact having lower symmetry. Both of these structures are locally polar, with sizable polarization, ~10 μC/cm2 due to the dipoles on the organic. They become energetically degenerate in the volume range, V ~ 250 Å3/f.u–265 Å3/f.u. We also find very significant dependence of the band gap on the local structure. This type of transition is analogous to a transition between two ferroelectric structures, where in-spite of strong electron phonon coupling, there is strong screening of charged defects which can lead to enhanced mobility and charge collection. The results provide insights into the enhanced light absorption near the band edge and good charge collection in this material.

The discovery of novel materials for thermoelectric energy conversion has potential to be accelerated by data-driven screening combined with high-throughput calculations. One way to increase the efficacy of successfully choosing a candidate material is through its evaluation using transport descriptors. Using a data-driven screening, we selected 12 potential candidates in the trigonal ABX2 family, followed by charge transport property simulations from first principles. The results suggest that carrier scattering processes in these materials are dominated by ionised impurities and polar optical phonons, contrary to the oft-assumed acoustic-phonon-dominated scattering. Using these data, we further derive ground-state transport descriptors for the carrier mobility and the thermoelectric powerfactor. In addition to low carrier mass, high dielectric constant was found to be an important factor towards high carrier mobility. A quadratic correlation between dielectric constant and transport performance was established and further validated with literature. Looking ahead, dielectric constant can potentially be exploited as an independent criterion towards improved thermoelectric performance. Combined with calculations of thermal conductivity including Peierls and inter-branch coherent contributions, we conclude that the trigonal ABX2 family has potential as high performance thermoelectrics in the intermediate temperature range for low grade waste heat harvesting. Agency for Science, Technology and Research (A*STAR) National Research Foundation (NRF) T. D., M. B. S., G. W., and S.-W. Y. acknowledge the support of Agency for Science, Technology and Research (A*STAR) of Singapore (Grant No. 1527200024). J. R.-G., D. V. M. R., P. K., A. A., and K. H. would like to acknowledge the Accelerated Materials Development for Manufacturing Program at A*STAR via the AME Programmatic Fund by the Agency for Science, Technology and Research under Grant No. A1898b0043. K. H. would like to acknowledge funding via the NRF Fellowship NRF-NRFF13-2021. J. R.-G. and I. N. would like to thank A*STAR Graduate Academy's ARAP programme for funding J. R.-G.'s graduate studies in IMRE, A*STAR. M. O. and J. S. would like to acknowledge JSPS KAKENHI (19H00744, 20K14661) and JST CREST (JPMJCR20Q3).

A mild, oxidant-free, and selective Cp*CoIII -catalyzed amidation of thioamides with robust dioxazolone amidating agents via C(sp3 )-H bond activation to generate the desired amidated products is reported. The method is efficient and allows for the C-H amidation of a wide range of functionalized thioamides with aryl-, heteroaryl-, and alkyl-substituted dioxazolones under the Cp*CoIII -catalyzed conditions. The observed regioselectivity towards primary C(sp3 )-H activation is supported by computational studies and the cyclometalation is proposed to proceed by means of an external carboxylate-assisted concerted metalation/deprotonation mechanism. The reported method is a rare example of the use of a directing group other than the commonly used pyridine and quinolone classes for Cp*CoIII -catalyzed C(sp3 )-H functionalization and the first to exploit thioamides.

The working mechanism of polycarboxylate ether (PCE) type superplasticisers in concrete was studied from the point of view of conformational changes of the polymer simulated by molecular dynamics in pure water and cement pore solution. Three typical types of PCEs, namely a methoxy polyethyleneglycol monomethacrylate–sodium methacrylate copolymer (PCEM), a polyethyleneglycol mono allyl ether–sodium maleate copolymer (PCEA) and a polyethyleneglycol mono (3-methyl-3-butenyl) ether–sodium acrylate copolymer (PCEI) were investigated using large-scale atomistic molecular dynamics simulations. It was observed that the PCE polymers which possess negatively charged backbones were stretched in water due to electrostatic repulsion. However, they were found to be significantly shrunken and distorted in synthetic cement pore solution, depending on the polyethylene glycol (PEG) density along the backbone, resulting in the aggregation of PEG side chains due to the salting-out effect.

A computationally efficient first-principles approach to predict intrinsic semiconductor charge transport properties is proposed. By using a generalized Eliashberg function for short-range electron–phonon scattering and analytical expressions for long-range electron–phonon and electron–impurity scattering, fast and reliable prediction of carrier mobility and electronic thermoelectric properties is realized without empirical parameters. This method, which is christened “Energy-dependent Phonon- and Impurity-limited Carrier Scattering Time AppRoximation (EPIC STAR)” approach, is validated by comparing with experimental measurements and other theoretical approaches for several representative semiconductors, from which quantitative agreement for both polar and non-polar, isotropic and anisotropic materials is achieved. The efficiency and robustness of this approach facilitate automated and unsupervised predictions, allowing high-throughput screening and materials discovery of semiconductor materials for conducting, thermoelectric, and other electronic applications. Agency for Science, Technology and Research (A*STAR) National Supercomputing Centre (NSCC) Singapore Published version This work is supported by Agency for Science, Technology and Research (A*STAR) of Singapore (1527200024). Computational resources are provided by the National Supercomputing Centre Singapore (NSCC) and A*STAR Computational Resource Centre (A*CRC). K.H. also acknowledges funding from the Accelerated Materials Development for Manufacturing Program at A*STAR via the AME Programmatic Fund by the Agency for Science, Technology and Research under Grant No. A1898b0043.

We use ab initio molecular dynamics (AIMD) simulations to build an amorphous model of GeSb 2 Te 4 and nanosecond-long annealing AIMD simulations to construct its Time-Temperature-Transformation (TTT) and Continuous-Heating-Transformation (CHT) diagrams. The critical cooling rate for amorphous GeSb 2 Te 4 , derived from the “nose” of the TTT diagram, is in the range 470–1100 K/ns. The Kissinger analysis of the non-isothermal crystallization kinetics suggests that it follows a non-Arrhenius crystallization behavior in which the crystallization temperature is upshifted by the heating rates. These results, from unprecedentedly long AIMD simulations, provide a detailed picture of the complex crystallization of GST alloys at the extremely small time and length scales relevant to phase change memory devices.

KMn/Al 2 O 3 catalysts with different K:Mn molar ratios were synthesized by a facile impregnation method and attempted for CO oxidation. The correlation in between potassium-dopant amount and the structure/catalytic activity of KMn/Al 2 O 3 catalysts were investigated. Doping small amount of potassium (K:Mn mole ratio less than 1:10) to Mn/Al 2 O 3 catalyst efficiently enhanced the catalytic activity of Mn/Al 2 O 3 catalyst. We found that the K 1 Mn 10 /Al 2 O 3 catalyst exhibited the best CO oxidation activity with the TOF of 1.5 × 10 −3 s −1 for 100% CO conversion at 260 °C, which is 50 °C lower than that on Mn/Al 2 O 3 catalyst. However, excessive amounts of potassium led to β-to-α-MnO 2 phase transformation and poor catalytic performance. DFT calculations combined with multiple characterization techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), O 2 temperature-programmed desorption (O 2 -TPD) and hydrogen temperature-programmed reduction (H 2 -TPR) were performed to provide a deep insight into the K-doping effect. The results suggested that the addition of an appropriate amount of potassium to Mn/Al 2 O 3 catalyst improved the dispersion of manganese oxide, the mobility and reactivity of surface lattice oxygen, thus significantly improved the catalyst activity.

In contrast to conventional phase-change materials we show that amorphous FeTe displays higher electrical conductivity and optical reflectivity than its crystal phase. This anomalous phenomenon is rooted in the delocalization of Te-p electrons in the amorphous phase. Originally existing as localized lone-pairs in the layered-like crystalline structure, Te-p electrons hybridize with empty Fe-d orbitals to generate p-d antibonding states below the Fermi level in the amorphous phase, which shifts up the amorphous phase valence band and results in delocalization of the valence band electrons to account for the concurrent anomalies. The unraveled lone-pair hybridization/dehybridization mechanism presents a paradigm for identifying anomalous phase-change materials.

Despite central roles in solidification and crystal growth, the solid-liquid interface energy σsl of the multicomponent metallic alloys is scarce and scattered because of the experimental complexity in measurements. Moreover, the theoretical prediction of σsl of the metallic alloy has been long suffered from the incomplete understanding of the solid-liquid interface structures. In this paper, the solid-liquid interface of the metallic alloy is reduced to a two-dimensional layer composed of the solid sublattice and liquid sublattice that is further sandwiched by the bulk solid and liquid phases. This enables the well-defined enthalpy and entropy hence the Gibbs energy model of the metallic solid-liquid interface layer. Via a constraint minimization of the solid-liquid interface layer Gibbs energy, the composition- and temperature-dependent σsl of the Al-based and Ag-based alloys are calculated by coupling with the available thermodynamic model parameters of the alloys. The calculation results are validated by the experimental data. It demonstrates that the built interface sublattice model offers a self-consistent framework for the automatic prediction of σsl of the metallic alloys ranging from the binary to a multicomponent system. It thus provides a more compelling solution to the long-standing issue associated with the modeling of the solid-liquid interface thermodynamics of the metallic alloys under both undercooling and equilibrium states.

Organo-lead halide perovskite solar cells represent a revolutionary shift in solar photovoltaics, introducing relatively soft defect containing semiconductors as materials with excellent charge collection for both electrons and holes. Although they are based on the nominally simple cubic perovskite structure, these compounds are in fact very complex. For example, in (CH3NH3)PbI3 the dynamics and ensuing structural fluctuations associated with the (CH3NH3)+ ions and the interplay with the electronic properties are still not fully understood, despite extensive study. Here, using ab-initio calculations, we show that at room and higher temperature, the rotation of CH3NH3 molecules can be viewed as effectively giving local structures that are cubic and tetragonal like from the point of view of the PbI3 framework, though in fact having lower symmetry. Both of these structures are locally polar, with sizable polarization, ~10 μC/cm2 due to the dipoles on the organic. They become energetically degenerate in the volume range, V ~ 250 Å3/f.u–265 Å3/f.u. We also find very significant dependence of the band gap on the local structure. This type of transition is analogous to a transition between two ferroelectric structures, where in-spite of strong electron phonon coupling, there is strong screening of charged defects which can lead to enhanced mobility and charge collection. The results provide insights into the enhanced light absorption near the band edge and good charge collection in this material.

We report first principles calculations aimed at understanding the dopant chemical potential modulation on the oxygen vacancy formation in In 2 O 3 . Relaying on our results, it implies that oxygen vacancies are deep donors in undoped In 2 O 3 and change to shallow donors with embedded Zn and Al in contrast to previous expectations of native carrier from oxygen vacancy. Our results well explain the anomalous carrier concentration increase in Zn and Al codoped In 2 O 3 . Our proposed models reveal the chemical potential modulation on oxygen vacancy formation and lead to a natural oxygen vacancy formation mechanism in the presence of metallic dopants in In 2 O 3 .

The conformations of polycarboxylate ether (PCE) type superplasticizer polymers adsorbed on the surface of MgO in cement pore solution are simulated by molecular dynamics (MD). Three types of PCEs commonly applied to concrete are simulated, namely a methacrylate type PCE (PCEM-P), an allyl ether type PCE (PCEA-P), and an isoprenyl ether type PCE (PCEI-P) with ethylene oxide (EO) unit numbers (P) of 25, 34 and 25, respectively. It is observed that the adsorbed layer thickness is inversely proportional to the experimentally measured adsorbed amount at the initial paste flow of 26 ± 0.5 cm. Simulation results indicate that the adsorbed layer thickness is sensitive to the initial polymer orientations against the model MgO surface. I.e., polymer molecules initially placed parallel/perpendicularly against the MgO surface gradually forms a train shaped or a loop and tail adsorption profile, respectively. As a result, the loop and tail shaped conformation gives a higher layer thickness.

Fluorescence lifetimes were evaluated using TD-DFT under different approximations for the emitting molecule and various exchange–correlation functionals, such as B3LYP, BMK, CAM-B3LYP, LC-BLYP, M06, M06-2X, M11, PBE0, ωB97, ωB97X, LC-BLYP*, and ωB97X* where the range-separation parameters in the last two functionals were tuned in a non-empirical fashion. Changes in the optimised molecular geometries between the ground and electronically excited states were found to affect the quality of the calculated lifetimes significantly, while the inclusion of vibronic features led to further improvements over the assumption of a vertical electronic transition. The LC-BLYP* functional was found to return the most accurate fluorescence lifetimes with unsigned errors that are mostly within 1.5 ns of experimental values.

The C-H activation in the tandem, "merry-go-round", [(dppp)Rh]-catalyzed (dppp=1,3-bis(diphenylphosphino)propane), four-fold addition of norborene to PhB(OH)2 has been postulated to occur by a C(alkyl)H oxidative addition to square-pyramidal Rh(III) -H species, which in turn undergoes a C(aryl)-H reductive elimination. Our DFT calculations confirm the Rh(I) /Rh(III) mechanism. At the IEFPCM(toluene, 373.15 K)/PBE0/DGDZVP level of theory, the oxidative addition barrier was calculated to be 12.9 kcal mol(-1) , and that of reductive elimination was 5.0 kcal mol(-1) . The observed selectivity of the reaction correlates well with the relative energy barriers of the cycle steps. The higher barrier (20.9 kcal mol(-1) ) for norbornyl-Rh protonation ensures that the reaction is steered towards the 1,4-shift (total barrier of 16.3 kcal mol(-1) ), acting as an equilibration shuttle. The carborhodation (13.2 kcal mol(-1) ) proceeds through a lower barrier than the protonation (16.7 kcal mol(-1) ) of the rearranged aryl-Rh species in the absence of o- or m-substituents, ensuring multiple carborhodations take place. However, for 2,5-dimethylphenyl, which was used as a model substrate, the barrier for carborhodation is increased to 19.4 kcal mol(-1) , explaining the observed termination of the reaction at 1,2,3,4-tetra(exo-norborn-2-yl)benzene. Finally, calculations with (Z)-2-butene gave a carborhodation barrier of 20.2 kcal mol(-1) , suggesting that carborhodation of non-strained, open-chain substrates would be disfavored relative to protonation.

Density functional theory calculations are performed to study CO oxidations on pure Pd(1 1 1) surface as well as on its Ni alloy nanostructures. Our calculations demonstrate a dependency of catalytic properties to the Ni occupancy site in the alloys. Furthermore, our results also show that optimal compressive strain (around 5%) of the alloy maybe beneficial to lower the reaction barrier and a compressive strain beyond 7% induces a distortion on the surface that eliminate the adsorption site for the reacting species. Based on our results, we propose that the Pd-Ni alloy with sandwich structure could be a potential candidate identified for lowering the cost of Pd alloys in the catalysis of the CO oxidation reaction. This new structure illustrates a potential lowering in the CO oxidation barrier. Furthermore, our results also indicate that the partial replacement of cheaper Ni into the Pd catalyst should not adversely affect the catalytic property.

The self-assembly and self-organization of small molecules at the surface of nanoparticles constitute a potential route towards the preparation of advanced protein-like nanosystems. However, their structural characterization, critical to the design of bio-nanomaterials with well-defined biophysical and biochemical properties, remains highly challenging. Here, a computational model for peptide-capped gold nanoparticles is developed using experimentally characterized CALNN-and CFGAILSS-capped gold nanoparticles as a benchmark. The structure of CALNN and CFGAILSS monolayers is investigated by both structural biology techniques and molecular dynamics simulations. The calculations reproduce the experimentally observed dependence of the monolayer secondary structure on peptide capping density and on nanoparticle size, thus giving us confidence in the model. Furthermore, the computational results reveal a number of new features of peptide-capped monolayers, including the importance of sulfur movement for the formation of secondary structure motifs, the presence of water close to the gold surface even in tightly packed peptide monolayers, and the existence of extended 2D parallel β-sheet domains in CFGAILSS monolayers. The model developed here provides a predictive tool that may assist in the design of further bio-nanomaterials.

Lithium nitrate (LiNO3) is known as an important electrolyte additive in lithium-sulfur (Li-S) batteries. The prevailing understanding is that LiNO3 reacts with metallic lithium anode to form a passivation layer which suppresses redox shuttles of lithium polysulfides, enabling good rechargeability of Li-S batteries. However, this view is seeing more challenges in the recent studies, and above all, the inability of inhibiting polysulfide reduction on Li anode. A closely related issue is the progressive reduction of LiNO3 on Li anode which elevates internal resistance of the cell and compromises its cycling stability. Herein, we systematically investigated the function of LiNO3 in redox-shuttle suppression, and propose the suppression as a result of catalyzed oxidation of polysulfides to sulfur by nitrate anions on or in the proximity of the electrode surface upon cell charging. This hypothesis is supported by both density functional theory calculations and the nitrate anions-suppressed self-discharge rate in Li-S cells. The catalytic mechanism is further validated by the use of ruthenium oxide (RuO2, a good oxygen evolution catalyst) on cathode, which equips the LiNO3-free cell with higher capacity and improved capacity retention over 400 cycles.

Many fatal neurodegenerative diseases such as Alzheimer’s, Parkinson, the prion-related diseases, and non-neurodegenerative disorders such as type II diabetes are characterized by abnormal amyloid fiber aggregates, suggesting a common mechanism of pathogenesis. We have discovered that a class of systematically designed natural tri- to hexapeptides with a characteristic sequential motif can simulate the process of fiber assembly and further condensation to amyloid fibrils, probably via unexpected dimeric α-helical intermediate structures. The characteristic sequence motif of the novel peptide class consists of an aliphatic amino acid tail of decreasing hydrophobicity capped by a polar head. To our knowledge, the investigated aliphatic tripeptides are the shortest ever reported naturally occurring amino acid sequence that can adopt α-helical structure and promote amyloid formation. We propose the stepwise assembly process to be associated with characteristic conformational changes from random coil to α-helical intermediates terminating in cross-β peptide structures. Circular dichroism and X-ray fiber diffraction analyses confirmed the concentration-dependent conformational changes of the peptides in water. Molecular dynamics simulating peptide behavior in water revealed monomer antiparallel pairing to dimer structures by complementary structural alignment that further aggregated and stably condensed into coiled fibers. The ultrasmall size and the dynamic facile assembly process make this novel peptide class an excellent model system for studying the mechanism of amyloidogenesis, its evolution and pathogenicity. The ability to modify the properties of the assembled structures under defined conditions will shed light on strategies to manipulate the pathogenic amyloid aggregates in order to prevent or control aggregate formation.

Positive and negative third-order optical nonlinearities have been investigated in single-stranded DNA wrapped semiconducting single-walled carbon nanotubes. It is found that the redox reactions of hydrogen peroxide can reverse the sign of the third-order nonlinearity. The observation proves that the lowest unoccupied molecular orbital has a lower density of electronic states than that of the highest occupied molecular orbital. A three-energy-level model is used to explain the effect of the redox reactions. Raman spectroscopy has also been used to investigate the interaction between single-walled carbon nanotubes and single-stranded DNA.

We present a theoretical investigation for the adsorptions of triangular nitrogen trimer radical (N3) at both the hollow (H3) and fourfold coordinated top (T4) sites on boron-terminated (111) (B(111)) surface of cubic boron nitride (c-BN) in terms of structure, adsorption energy, band structure and work function. For the first time, we explore the H3 and T4 adsorption mechanisms. Moreover, we study the subsequent co-adsorption of N3, boron and hydrogen atoms on the same adsorption site on the B(111) surface, which will form either pyramid quantum cluster or nearly planar adsorbate. We find that the surface band structure varies substantially depending on the types of terminated surface formed (changing from metallic to semi-conducting), and consequently, the surface work function changes. These results indicate the electronic characteristics of the B(111) surface can be tuned readily using chemical co-adsorption, suggesting its potential for chemical sensing applications.

High-level ab initio calculations, including variants of the Wn and G3 procedures, have been used to determine the structures and heats of formation of the alkali metal and alkaline earth metal oxides and hydroxides (M2O, MOH: M = Li, Na, and K; MO, M(OH)2: M = Be, Mg, and Ca). Our best structures were obtained at the CCSD(T)(riv,rv)/aug‘-cc-pWCVQZ level and are in uniformly close agreement with available experimental data, with a mean absolute deviation from experimental metal−oxygen bond lengths of just 0.007 A.Structures obtained with CCSD(T)/cc-pWCVQZ, B3-LYP/cc-pVTZ, B3-LYP/6-31G(2df,p), and MP2(full)/6-311+G(3df,2p) are also in good agreement with experiment. Zero-point vibrational energies and enthalpy temperature corrections are found to be relatively insensitive to the various procedures employed. However, the heats of formation for these molecules are challenging targets for high-level ab initio procedures. In the Wn-type procedures, it is found that expanding the correlation space on the meta...

The authors gratefully acknowledge generous allocations of computing time on the Compaq Alphaserver of the National Facility of the Australian Partnership for Advanced Computing, Australian National University Supercomputer Facility, and the support of the Australian Research Council.

Objective: Mice homozygous for targeted deletion of the gene encoding fibroblast growth factor receptor 3 (FGFR3−/−) develop kyphoscoliosis by 2 months of age. The first objective of this study was to use high resolution X-ray to characterize curve progression in vivo and micro CT to quantify spine architecture ex vivo in FGFR3−/− mice. The second objective was to determine if slow release of the bone anabolic peptide parathyroid hormone related protein (PTHrP-1-34) from a pellet placed adjacent to the thoracic spine could inhibit progressive kyphoscoliosis. Materials and methods: Pellets loaded with placebo or PTHrP-1-34 were implanted adjacent to the thoracic spine of 1-month-old FGFR3−/− mice obtained from in house breeding. X rays were captured at monthly intervals up to 4 months to quantify curve progression using the Cobb method. High resolution post-mortem scans of FGFR3−/− and FGFR3+/+ spines, from C5/6 to L4/5, were captured to evaluate the 3D structure, rotation, and micro-architecture of the affected vertebrae. Un-decalcified and decalcified histology were performed on the apical and adjacent vertebrae of FGFR3−/− spines, and the corresponding vertebrae from FGFR3+/+ spines. Results: The mean Cobb angle was significantly greater at all ages in FGFR3−/− mice compared with wild type mice and appeared to stabilize around skeletal maturity at 4 months. 3D reconstructions of the thoracic spine of 4-month-old FGFR3−/− mice treated with PTHrP-1-34 revealed correction of left/right asymmetry, vertebral rotation, and lateral displacement compared with mice treated with placebo. Histologic analysis of the apical vertebrae confirmed correction of the asymmetry in PTHrP-1-34 treated mice, in the absence of any change in bone volume, and a significant reduction in the wedging of intervertebral disks (IVD) seen in placebo treated mice. Conclusion: Local treatment of the thoracic spine of juvenile FGFR3−/− mice with a bone anabolic agent inhibited progression of scoliosis, but with little impact on kyphosis. The significant improvement in IVD integrity suggests PTHrP-1-34 might also be considered as a therapeutic agent for degenerative disk disorders.

KitW-sh mice carry an inactivating mutation in the gene encoding the receptor for stem cell factor, which is expressed at high levels on the surface of haematopoietic precursor cells. The mutation results in mast cell deficiency, a variety of defects in innate immunity and poorly defined abnormalities in bone. The present study was designed to characterise healing of a cortical window defect in skeletally mature KitW-sh mice using high-resolution micro computed tomographic imaging and histological analyses. The cortical bone defect healed completely in all wild type mice but failed to heal in about half of the KitW-sh mice by 12 weeks post-operative. Defective healing was associated with premature and excessive expression of TRAP positive cells embedded in fibrous marrow but with little change in ALP activity. Immuno-histochemical analyses revealed reduced CD34 positive vascular endothelial cells and F4/80 positive macrophages at 1 and 2 weeks post-operative. Impaired bone healing in the KitW-sh mice was therefore attributed to altered catabolic activity, impaired re-vascularisation and compromised replacement of woven with compact bone.

We explore BiFeO3 under tensile strain using first-principles calculations. We find that the actual structures are more complex than what had been previously thought and that there is a strong shear deformation type structural instability which modifies the properties. Specifically, we find that normal tensile strain leads to structural instabilities with a large induced shear deformation in (001) BiFeO3 thin films. These induced shear deformations in (001) BiFeO3 thin films under tension stabilize the (001) BiFeO3 thin films and lead to Cc and Ima2 phases that are more stable than the Pmc21 phase at high tensile strain. The induced shear deformation shifts the Cc to Ima2 phase transition towards lower tensile strain region (~1% less), prevents monoclinic tilt and oxygen octahedral tilts and increases the ferroelectric polarization. The induced shear deformation also strongly affects the electronic structure. The results are discussed in relation to growth of BiFeO3 thin films on cubic and tetragonal substrates involving high levels of tensile strain.

We describe a flexible, transparent plastic substrate for flat panel display applications. Using roll-coating techniques, we apply a composite thin film barrier to commercially available polymers, which restricts moisture and oxygen permeation to undetectable levels using conventional permeation test equipment. The barrier film can be capped with a thin film of transparent conductive oxide in the same roll-coater, yielding an engineered substrate (Barix™) for next generation, rugged, lightweight or flexible displays. The substrate is sufficiently impermeable to moisture and oxygen for application to moisture-sensitive display applications, such as organic light emitting displays. This enables, for the first time, lightweight and flexible emissive organic displays.

We study the transport properties, in particular, the thermoelectric figure of merit ZT of armchair graphene nanoribbons, AGNR-N (for N=4-12, with widths ranging from 3.7 to 13.6~\AA) through strain engineering, where N is the number of carbon dimer lines across the AGNR width. We find that the tensile strain applied to AGNR-$N$ changes the transport properties by modifying the electronic structures and phonon dispersion relations. The tensile strain increases the ZT value of the AGNR-$N$ families with N=3p and N=3p+2, where $p$ is an integer. Our analysis based on accurate density-functional theory calculations suggests a possible route to increase the ZT values of AGNR-$N$ for potential thermoelectric applications., Comment: 6 pages

Bi${}_{2}$Se${}_{3}$ and Bi${}_{2}$Te${}_{3}$ are layered compounds of technological importance, being excellent thermoelectric materials as well as topological insulators. We report density functional theory calculations of the atomic, electronic, and thermoelectric properties of strained bulk and thin-film Bi${}_{2}$Se${}_{3}$ and Bi${}_{2}$Te${}_{3}$, focusing on an appropriate description of van der Waals (vdW) interactions. The calculations show that the van der Waals density functional (vdW-DF) with Cooper's exchange (vdW-DF${}^{\mathrm{C}09}$${}_{x}$) can reproduce closely the experimental interlayer distances in unstrained Bi${}_{2}$Se${}_{3}$ and Bi${}_{2}$Te${}_{3}$. Interestingly, we predict atomic structures that are in much better agreement with the experimentally determined structure from Nakajima than that obtained from Wyckoff, especially for Bi${}_{2}$Se${}_{3,}$ where the difference in atomic structures qualitatively changes the electronic band structure. The band structure obtained using the Nakajima structure and the vdW-DF${}^{\mathrm{C}09}$${}_{x}$ optimized structure are in much better agreement with previous reports of photoemission measurements, than that obtained using the Wyckoff structure. Using vdW-DF${}^{\mathrm{C}09}$${}_{x}$ to fully optimize atomic structures of bulk and thin-film Bi${}_{2}$Se${}_{3}$ and Bi${}_{2}$Te${}_{3}$ under different in-plane and uniaxial strains, we predict that the electronic bandgap of both the bulk materials and thin films decreases with tensile in-plane strain and increases with compressive in-plane strain. We also predict, using the semiclassical Boltzmann approach, that the magnitude of the $n$-type Seebeck coefficient of Bi${}_{2}$Te${}_{3}$ can be increased by the compressive in-plane strain while that of Bi${}_{2}$Se${}_{3}$ can be increased with tensile in-plane strain. Further, the in-plane power factor of $n$-doped Bi${}_{2}$Se${}_{3}$ can be increased with compressive uniaxial strain while that of $n$-doped Bi${}_{2}$Te${}_{3}$ can be increased by compressive in-plane strain. Strain engineering thus provides a direct method to control the electronic and thermoelectric properties in these thermoelectric topological insulator materials.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; Background: The polyphenolic products of the phenylpropanoid pathway, including proanthocyanidins, anthocyanins and flavonols, possess antioxidant properties that may provide health benefits. To investigate the genetic architecture of control of their biosynthesis in apple fruit, various polyphenolic compounds were quantified in progeny from a 'Royal Gala'x 'Braeburn' apple population segregating for antioxidant content, using ultra high performance liquid chromatography of extracts derived from fruit cortex and skin. Results: Construction of genetic maps for 'Royal Gala' and 'Braeburn' enabled detection of 79 quantitative trait loci (QTL) for content of 17 fruit polyphenolic compounds. Seven QTL clusters were stable across two years of harvest and included QTLs for content of flavanols, flavonols, anthocyanins and hydroxycinnamic acids. Alignment of the parental genetic maps with the apple whole genome sequence in silico enabled screening for co-segregation with the QTLs of a range of candidate genes coding for enzymes in the polyphenolic biosynthetic pathway. This co-location was confirmed by genetic mapping of markers derived from the gene sequences. Leucoanthocyanidin reductase (LAR1) co-located with a QTL cluster for the fruit flavanols catechin, epicatechin, procyanidin dimer and five unknown procyanidin oligomers identified near the top of linkage group (LG) 16, while hydroxy cinnamate/quinate transferase (HCT/HQT) co-located with a QTL for chlorogenic acid concentration mapping near the bottom of LG 17. Conclusion: We conclude that LAR1 and HCT/HQT are likely to influence the concentration of these compounds in apple fruit and provide useful allele-specific markers for marker assisted selection of trees bearing fruit with healthy attributes.

The geometries, enthalpies of formation (DeltaH(o)(f)), separations of electronic states, electron affinities, gas-phase acidities, and bond dissociation energies associated with the alkali metal monoxide anions (MO(-)), monoxide radicals (MO(*)), and hydroxides (MOH) (M = Li, Na, and K) have been investigated using single-reference and multireference variants of the WnC procedures. Our best estimates of the DeltaH(o)(f) values for the ground states at 298 K are as follows: 8.5 ((3)Pi LiO(-)), 48.5 ((2)Pi LiO(*)), -243.4 ((1)Sigma(+) LiOH), 34.2 ((3)Pi NaO(-)), 86.4 ((2)Pi NaO(*)), -190.8 ((1)Sigma(+) NaOH), 15.1 ((1)Sigma(+) KO(-)), 55.9 ((2)Sigma(+) KO(*)), and -227.0 ((1)Sigma(+) KOH) kJ mol(-1). While the LiO(*) and NaO(*) radicals have (2)Pi ground states, for KO(*), the (2)Sigma(+) and (2)Pi electronic states lie very close in energy, with our best estimate being a preference for the (2)Sigma(+) state by 1.1 kJ mol(-1) at 0 K. In a similar manner, the ground state for MO(-) changes from (3)Pi for LiO(-) and NaO(-) to (1)Sigma(+) for KO(-). The (1)Sigma(+) state of KO(-) is indicated by the calculated T(1) diagnostic and the SCF contribution to the total atomization energy to have a significant degree of multireference character. This leads to a difference of more than 100 kJ mol(-1) between the single-reference W2C and multireference W2C-CAS-ACPF and W2C-CAS-AQCC estimates for the (1)Sigma(+) DeltaH(o)(f) for KO(-).

Introduction: Exercise improves functional outcome and symptoms for certain cancer populations, but the feasibility, efficacy, and safety of structured exercise in patients with lung cancer is unknown. In this study, we examined the feasibility of a hospital-based exercise program for patients with advanced non-small cell lung cancer. Methods: This study included patients with newly diagnosed advanced stage non-small cell lung cancer and Eastern Cooperative Oncology Group performance status 0–1. A physical therapist facilitated twice-weekly sessions of aerobic exercise and weight training over an 8-week period. The primary end point was feasibility of the intervention, defined as adherence to the exercise program. Secondary endpoints included functional capacity, measured by the 6-minute walk test and muscle strength, as well as quality of life, lung cancer symptoms and fatigue, measured by the Functional Assessment of Cancer Therapy-lung and Functional Assessment of Cancer Therapy-fatigue scales. Results: Between October 2004 and August 2007, 25 patients enrolled in the study. All participants received anticancer therapy during the study period. Twenty patients (80%) underwent the baseline physical therapy evaluation. Eleven patients (44%) completed all 16 sessions. An additional 6 patients attended at least 6 sessions (range, 6–15), and 2 patients only attended one session. Study completers experienced a significant reduction in lung cancer symptoms and no deterioration in their 6-minute walk test or muscle strength. Conclusions: Although the majority of participants attempted the exercise program, less than half were able to complete the intervention. Those who completed the program experienced an improvement in their lung cancer symptoms. Community-based or briefer exercise interventions may be more feasible in this population.

Lithium monoxide anion (LiO − ) has been generated in the gas phase and is found to be a stronger base than methyl anion (CH 3 − ). This makes LiO − the strongest base currently known, and it will be a challenge to produce a singly charged or multiply charged anion that is more basic. The experimental acidity of lithium hydroxide is Δ H ° acid = 425.7 ± 6.1 kcal·mol −1 (1 kcal = 4.184 kJ) and, when combined with results of high-level computations, leads to our best estimate for the acidity of 426 ± 2 kcal·mol −1 .

A variety of theoretical procedures, including the high-level ab initio methods G3, G3[CC](dir,full), and W2C//ACQ, have been used to predict the structures and heats of formation of several small calcium-containing molecules (CaH, CaH2, CaO, CaOH, Ca(OH)2, CaF, CaF2, CaS, CaCl, and CaCl2). B3-LYP and CCSD(T) with both the (aug-)cc-pWCVQZ and (aug-)cc-pWCVQ+dZ basis sets are found to give molecular geometries that agree well with the experimental results. The CCSD(T)(riv)/(aug-)cc-pWCVQ+dZ results are found to be the most accurate, with a mean absolute deviation from experiment of just 0.008 angstroms. Zero-point vibrational energies (ZPVEs) and thermochemical corrections are found to be relatively insensitive to the level of theory, except in the case of molecules with highly anharmonic calcium-centered bending modes (CaH2, Ca(OH)2, CaF2, CaCl2), where special procedures need to be employed in order to obtain satisfactory results. Several potential improvements to the W2C method were investigated, most of which do not produce significant changes in the heats of formation. It was observed, however, that for CaO and CaS the scalar relativistic corrections are unexpectedly large and highly basis set dependent. In these cases, Douglas-Kroll CCSD(T)/(aug-)cc-pWCV5Z calculations appear to give a converged result. The G3[CC](dir,full) and best W2C-type heats of formation are both found generally to agree well with experimental values recommended in recent critical compendia. However, in some cases (CaO, Ca(OH)2, and CaF2), they differ from one another by more than their predicted error margins. The available experimental data are not sufficiently precise to distinguish definitively between the two sets of results although, in general, when discrepancies exist the W2C heats of formation are lower in energy and tend to be in better agreement with experiment. In the case of CaO, the W2C heat of formation (20.7 kJ mol(-1)) is approximately 20 kJ mol(-1) lower than the G3[CC](dir, full) result and most of the experimental data. Extensive investigation of possible refinements of the W2C method has failed to reveal any weaknesses that could account for this discrepancy. We therefore believe that the heat of formation of CaO is likely to lie closer to the more recent direct experimental determination of 27 kJ mol(-1) than to the value of approximately 40 kJ mol(-1) recommended in recent thermochemical reviews.

The red Pechmann dye is the exo-dimer of 4-phenyl-3-butenolide connected at the α-carbon by a double bond in a trans-fashion. The ring system is easily rearranged to trans-endo-fused bicyclic 6-membered lactone dimer (yellow). Both lactones can be singly or doubly amidated with primary amines leading to further color changes. The nature of the core heterocycle (exo- vs endo-), core heteroatom (O vs N) and additional substituents on the phenyl ring allows for exquisite control over color achievable within a single dye family. Herein we present a detailed investigation of modeling of the electronic spectra of the Pechmann dye family by time-dependent density functional theory (TDDFT). Whereas pure Hartree-Fock (HF) ab-initio calculation underestimates the UV/Vis absorption maximum, pure DFT leads to large overestimation. The accuracy of the prediction is highly dependent of the mix of HF and DFT, with BMK (42% HF) and M06-2X (54% HF) giving the closest match with the experimental value. Among all basis sets evaluated, the computationally-efficient, DFT-optimized DGDZVP showed the best chemical accuracy/size profile. Finally, the use of dispersion interaction-corrected (SMD) implicit solvation model was advantageous compared to the original IEFPCM. The absorption maxima of substituted Pechmann dyes and their rearranged lactone counterparts can be predicted with excellent accuracy (±6nm) at the optimal SCRF=SMD, toluene/TDBMK/DGDZVP//B3LYP/DGDZVP level of theory. Larger deviations were observed for amidated analogs or in more polar solvents (i.e., chloroform).