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Bipolar junction transistors (BJTs) are often used in spacecraft due to their excellent working characteristics. However, the complex space radiation environment induced primary knock-on atom (PKA) in BJTs through collisions, resulting in hard-to-recover displacement damage and affecting the electrical performance of electronic components. In this paper, the properties of PKAs induced by typical space-heavy ions (C, N, O, Fe) in BJTs are investigated using Monte Carlo simulations. The simulated results show that the energy spectrum of ion-induced PKAs is primarily concentrated in the low energy range (17-100 eV) and displays similar features across all tested ions. The PKAs induced by the collision of energetic ions have a large forward scattering angle, which is mainly around 88°. Moreover, PKA distribution within the transistor as a function of depth displays a peak characteristics, and the peak position is linearly proportional to the incident energy at a certain energy range. These simulation outcomes serve as crucial theoretical support for long-term semiconductor material defect evolution and ground testing of semiconductor devices.

The recently synthesized triangulenes with non-bonding edge states could have broad potential applications in magnetics, spintronics and electro-optics if they have appropriate electronic structure modulation. In the present work, strategies based on molecular orbital theory through heteroatom doping are proposed to redistribute, reduce or eliminate the spin of triangulenes for novel functional materials design, and the role of B, N, NBN, and BNB in such intended electronic structure manipulation is scrutinized. π-Extended triangulenes with tunable electronic properties could be potential nonlinear optical (NLO) materials with appropriate inhibition of their polyradical nature. The elimination of spin is achieved by B, N, NBN, and BNB doping with the intended geometric arrangement for enhanced polarity. Intended doping of BNB results in an optimal structure with large static first hyperpolarizability (〈

The high stability, feasible modification, and good π-conjugation of porphyrin derivatives render these porphyrin-based nanomaterials suitable as potential third order nonlinear optical (NLO) materials. Introducing an azulene in pristine porphyrins can significantly improve the second order NLO properties of the system, and this is studied in the present work using density functional theory based methods and the sum-over-states model. The relative orientation of azulene plays a determinant role in the enhancement of the static first hyperpolarizability (〈

The magnetic velocity induction system (MAVIS) is commonly used for velocimetry in shock compression experiment. Due to some discrepancies, the variation in induced voltage amplitude is ambiguous, which makes the simulation of this experiment particularly significant. In this work, we have designed a MAVIS, which was used to determine the induced voltage amplitude and flyer velocity. We built a three-dimensional model of MAVIS and performed the simulations using the Analysis System Electromagnetics Suite. Additionally, we performed some experiments and compared the results of both studies on the basis of flyer thickness, radius, and velocity. It was established that the flyer velocity influenced the induced electromotive force (EMF) in the pick-up coils. The increase in flyer radius led to the increase in the induced EMF. The cut-off radius for flyers was also discussed in detail by computing the lowest induced EMFs at discrete flyer velocities and radii. Due to the eddy current loss, experimental data laid slightly lower than simulations. The simulation data have proved its accuracy within the experimental error range. Thus, it can be applied as an economical framework to calculate projectile velocity precisely, regardless of its geometry, and to estimate the trigger level of the oscilloscope before performing the experiments. In order to enhance the quality of induced voltage, we also proposed a new design consisting of three pick-up coils. This redesigned MAVIS contributed significantly in signal narrowing as well as controlled the loss in amplitude peaks that reduced the experimental uncertainty in flyer velocity

In view of the current and expected future rise in atmospheric CO2 concentrations, we examined the effect of elevated CO2 on photoinhibition of photosystem I (PSI) under fluctuating light in Arabidopsis thaliana. At 400 ppm CO2, PSI showed a transient over-reduction within the first 30 s after transition from dark to actinic light. Under the same CO2 conditions, PSI was highly reduced after a transition from low to high light for 20 s. However, such PSI over-reduction greatly decreased when measured in 800 ppm CO2, indicating that elevated atmospheric CO2 facilitates the rapid oxidation of PSI under fluctuating light. Furthermore, after fluctuating light treatment, residual PSI activity was significantly higher in 800 ppm CO2 than in 400 ppm CO2, suggesting that elevated atmospheric CO2 mitigates PSI photoinhibition under fluctuating light. We further demonstrate that elevated CO2 does not affect PSI activity under fluctuating light via changes in non-photochemical quenching or cyclic electron transport, but rather from a rapid electron sink driven by CO2 fixation. Therefore, elevated CO2 mitigates PSI photoinhibition under fluctuating light at the acceptor rather than the donor side. Taken together, these observations indicate that elevated atmospheric CO2 can have large effects on thylakoid reactions under fluctuating light.

The hydrogen adsorption capacity of dual-Ti-doped (7, 7) single-walled carbon nanotube (Ti-SWCNTs) has been studied by the first principles calculations. Ti atoms show different characters at different locations due to local doping environment and patterns. The dual-Ti-doped SWCNTs can stably adsorb up to six H2 molecules through Kubas interaction at the Ti2 active center. The intrinsic curvature and the different doping pattern of Ti-SWCNTs induce charge discrepancy between these two Ti atoms, and result in different hydrogen adsorption capacity. Particularly, eight H2 molecules can be adsorbed on both sides of the dual-Ti decorated SWCNT with ideal adsorption energy of 0.198 eV/H2, and the physisorption H2 on the inside Ti atom has desirable adsorption energy of 0.107 eV/H2, ideal for efficient reversible storage of hydrogen. The synergistic effect of Ti atoms with different doping patterns enhances the hydrogen adsorption capacity 4.5H2s/Ti of the Ti-doped SWCNT (VIII), and this awaits experimental trial.

In this work, an outstanding nanolayered tin phosphate with 15.0 A interlayer spacing, Sn (HPO4)2·3H2O (SnP–H+), has been synthesized by conventional hydrothermal method and first used in the adsorptive removal of Cr(III) from aqueous solution. A number of factors such as contact time, initial concentration of Cr(III), temperature, pH, and ionic strength on adsorption were investigated by batch tests. Moreover, the isothermal adsorption characteristics and kinetic model of Cr(III) onto SnP–H+ were studied. The results showed that the adsorption of Cr(III) by SnP–H+ was in accordance with the Langmuir adsorption isotherm model and the pseudo-second-order kinetic model. The adsorption capacity of Cr(III) onto SnP–H+ at temperature 40.0 °C and pH 3.0 could reach 81.1 mg g−1. And the distribution coefficient Kd was 23.0 g L−1. Overall, experiments certified that SnP–H+ was an excellent adsorbent that can effectively remove Cr(III) from aqueous solution.

Amyloid β (Aβ) induced microglial activation and attendant neuroinflammation play pivotal roles in Alzheimer's disease (AD) pathogenesis. Matrine is a natural anti-inflammation compound from the Chinese herbal medicine

The third order static and dynamic nonlinear optical (NLO) responses of Ih symmetry fullerenes (C60, C240, and C540) and fullerene onions (C60@C240 and C60@C240@C540) are predicted using the ZINDO method and the sum-over-states model. The static second hyperpolarizability of Ih symmetry fullerenes increases exponentially with fullerene size [from 10.00 × 10-34 esu in C60 to 3266.74 × 10-34 esu ≈ γ0(C60) × 92.63 in C540]. The external fields of strong third order NLO responses of Ih symmetry fullerenes change from ultra-violet (C60) to the visible region (C540) as the fullerene size increases. The outer layer fullerene in the fullerene onions has dominant contributions to the third order NLO properties of the fullerene onions, and the inter-shell charge-transfer excitations have conspicuous contributions to the third order NLO properties. The two-dimensional two-photon absorption spectra of C60 and C240 show that those fullerenes have strong two-photon absorptions in the visible region with short wavelength and in the ultra-violet region.

The Arabidopsis has 51 proteins annotated as serine carboxypeptidase-like (SCPL) enzymes. Although biochemical and cellular characterization indicates SCPLs involved in protein turnover or processing, little is known about their roles in plant metabolism. In this study, we identified an Arabidopsis mutant, bis4 (1-butanol insensitive 4), that was insensitive to the inhibitory effect of 1-butanol on seed germination. We cloned the gene that was defective in bis4 and found that it encoded an SCPL41 protein. Transgenic Arabidopsis plants constitutively expressing SCPL41 were generated, oil body staining and lipidomic assays indicated that SCPL41-overexpressing plants showed a decrease in membrane lipid content, especially digalactosyl diglyceride (DGDG) and monogalactosyl diglyceride (MGDG) contents, while the loss of SCPL41 increased the membrane lipid levels compared with those in wild-type plants. These findings suggested that SCPL41 had acquired novel functions in membrane lipid metabolism.

The current understanding of the biological impacts of silver nanoparticles (AgNPs) is restricted to the direct interactions of the particles with biota. Very little is known about their intracellular fate and subsequent toxic consequences. In this research we investigated the uptake, internal fate (i,e., Ag subcellular partitioning and chemical forms), and phytotoxicity of AgNPs in lettuce following foliar versus root exposure. At the same AgNP exposure concentrations, root exposure led to more deleterious effects than foliar exposure as evidenced by a larger extent of reduced plant biomass, elevated oxidative damage, as well as a higher amount of ultrastructural injuries, despite foliar exposure leading to 2.6-7.6 times more Ag bioaccumulation. Both Ag subcellular partitioning and chemical forms present within the plant appeared to elucidate this difference in toxicity. Following foliar exposure, high Ag in biologically detoxified metals pool (29.2-53.0% by foliar exposure vs. 12.8-45.4% by root exposure) and low Ag proportion in inorganic form (6.1-11.9% vs. 14.1-19.8%) potentially associated with AgNPs tolerance. Silver-containing NPs (24.8-38.6 nm, 1.5-2.3 times larger than the initial size) were detected in lettuce plants exposed to NPs and to dissolved Ag+, suggesting possible transformation and/or aggregation of AgNPs in the plants. Our observations show that the exposure pathway significantly affects the uptake and internal fate of AgNPs, and thus the associated phytotoxicity. The results are an important contribution to improve risk assessment of NPs, and will be critical to ensure food security.

The effect of heat treatment on microstructure and hardness of internal crack healing in a low carbon steel was studied. The internal cracks were produced into the samples by a drilling and compression method. The microstructure of crack healing zone was examined using optical microscopy (OM) and scanning electron microscopy (SEM). The hardness of crack healing zone was measured using a Vickers micro-hardness testing machine (FM-800). The results show that healing temperature plays a more significant role in internal crack healing than holding time. Compared as-quenched samples with as-normalized samples under the same healing parameters, it is found that cooling speed is also an important factor for internal crack healing. The migration and enrichment of iron atoms provide material source for recrystallization and grain growth of crack healing zone. The existence of micro-voids leads to the hardness of the ferrite in the crack healing zone lower than that in the matrix.

Altering the organic spacers in hybrid complexes of polyoxotungstates and long-chain α,ω-alkyldiphosphonates (Ln), by a single CH2 group (e.g.L6vs.L5), can steer the self-assembly processes into different paths. Even homologous hybrids of L5 and L4 have seen the spin ground states switch from S = 0 to S = 9 upon shortening the chain length (L5vs.L4).

Tamarix ramosissima is a traditional Chinese herbal medicine used for rheumatoid arthritis (RA) treatment in Northwest China. Chemical investigation of EtOH/H2O extracts of T. ramosissima led to the discovery of a new flavonol, ramosissimin (1), together with the known flavonoids compounds quercetin (2), quercetin-3'4'-dimethylether (3) and kaempferol (4). By means of high resolution electrospray ionization mass spectroscopy (HRESIMS) and 1D and 2D-NMR experiments, and after comparison with literature data, the structures of the compounds were determined. The effect of compound 1 on the viability of RA fibroblast-like synoviocytes (RA-FLS) was evaluated by MTT assay. Apoptosis-inducing effect of compound 1 in RA-FLS was further investigated by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay and activated caspase-3/7 level assessment using luminescent assay. The results revealed that ramosissimin displayed remarkable proliferation inhibitory effect in RA-FLS. Furthermore, compound 1 could significantly induce cellular apoptosis of RA-FLS and increase activated caspase-3/7 levels. It is suggested that ramosissimin may inhibit the proliferation of RA-FLS by inducing apoptosis.

This data article contains data related to the research article entitled “3D imaging of cell interactions with electrospun PLGA nanofiber membranes for bone regeneration” by Stachewicz et al. [1]. In this paper we include additional data showing degradation analysis of poly(d,l-lactide-co-glycolide acid) (PLGA) electrospun fibers in medium and air using fiber diameter distribution histograms. We also describe the steps used in “slice and view” tomography techniques with focused ion beam (FIB) microscopy and scanning electron microscopy (SEM) and detail the image analysis to obtain 3D reconstruction of osteoblast cell integration with electrospun network of fibers. Further supporting data and detailed information on the quantification of cell growth within the electrospun nanofiber membranes is provided.

The interaction between resident cells and electrospun nanofibers is critical in determining resultant osteoblast proliferation and activity in orthopedic tissue scaffolds. The use of techniques to evaluate cell-nanofiber interactions is critical in understanding scaffold function, with visualization promising unparalleled access to spatial information on such interactions. 3D tomography exploiting focused ion beam (FIB)-scanning electron microscopy (SEM) was used to examine electrospun nanofiber scaffolds to understand the features responsible for (osteoblast-like MC3T3-E1 and UMR106) cell behavior and resultant scaffold function. 3D imaging of cell-nanofiber interactions within a range of electrospun poly(d,l-lactide-co-glycolide acid) (PLGA) nanofiber scaffold architectures indicated a coherent interface between osteoblasts and nanofiber surfaces, promoting osteoblast filopodia formation for successful cell growth. Coherent cell-nanofiber interfaces were demonstrated throughout a randomly organized and aligned nanofiber network. Gene expression of UMR106 cells grown on PLGA fibers did not deviate significantly from those grown on plastic, suggesting maintenance of phenotype. However, considerably lower expression of Ibsp and Alpl on PLGA fibers might indicate that these cells are still in the proliferative phase compared with a more differentiated cell on plastic. This work demonstrates the synergy between designing electrospun tissue scaffolds and providing comprehensive evaluation through high resolution imaging of resultant 3-dimensional cell growth within the scaffold.Membranes made from electrospun nanofibers are potentially excellent for promoting bone growth for next-generation tissue scaffolds. The effectiveness of an electrospun membrane is shown here using high resolution 3D imaging to visualize the interaction between cells and the nanofibers within the membrane. Nanofibers that are aligned in one direction control cell growth at the surface of the membrane whereas random nanofibers cause cell growth into the membrane. Such observations are important and indicate that lateral cell growth at the membrane surface using aligned nanofibers could be used for rapid tissue repair whereas slower but more extensive tissue production is promoted by membranes containing random nanofibers.

The effect of plasma screening on the dynamic dipole polarizability (DPP) of two-electron ions Be2+, B3+, and C4+ has been investigated using highly correlated exponential wave functions within the framework of pseudostate summation technique and Debye screening concept. Plasma-screening effect on the oscillator strengths (OS) of the ultraviolet and visible series has also been investigated for the systems Li+, Be2+, B3+, C4+. The DPP are reported as functions of screening parameters. The OS for S-P transitions are also reported for various screening parameters. The OS and dynamic polarizability show interesting behavior with increasing screening strength and nuclear charge. © 2015 Wiley Periodicals, Inc.

We have investigated the doubly excited nonautoionizing states of heliumlike two electron ions from Li+ through Mg10+ using the exponential correlated exponential wave functions in the framework of the Ritz variational method. The metastable bound-excited 2pnf1,3Fe(4 ≤ n ≤ 7) and 2png1,3Go (5 ≤ n ≤ 8) states energies of heliumlike two-electron ions are reported along with the 2png1,3 Go (5 ≤ n ≤ 9) state energy eigenvalues of helium atom. Our upper-bound results for the 2pnf1,3Fe and 2png1,3Go states energies of Li+, Be2+, B3+ are the lowest values up to this date. The doubly excited nonautoionizing F and G states energy eigenvalues for heliumlike two-electron systems from C4+ through Mg10+ are reported for the first time in the literature.

The lowest-lying 10 isomers of C106 satisfying the isolated-pentagon rule (IPR) were predicted from 1233 IPR isomers with semiempirical and density functional theory based methods. The structures, stabilities, IR and UV spectroscopic, and the third-order nonlinear optical (NLO) properties of those low-lying isomers were explored in detail. Cs:331, C2:1194, and C1:534 are the three lowest-energy isomers with almost identical energies and could be observed in experiment. When the entropy effects in the isomeric fullerene system are taken into account, isomer C2:1194 prevails up to 3000 °C. In the high temperature region, the concentrations of those ten low-lying isomers are very similar, indicating that the isomers at high temperatures will be hard to isolate. The third-order NLO properties under external fields (0.0–3.0 eV) of the five lowest-lying isomers were analyzed, and the average NLO properties of those isomers were predicted at room temperature for experimental exploration.

It is important to understand the interface and interaction between the graphene layer, titanium carbide [TiC(111)] interlayer, and silicon carbide [SiC(0001[combining macron])] substrates in epitaxial growth of graphene on silicon carbide (SiC) substrates. In this study, the fully relaxed interfaces which consist of up to three layers of TiC(111) coatings on the SiC(0001[combining macron]) as well as the graphene layers interactions with these TiC(111)/SiC(0001[combining macron]) were systematically studied using the density functional theory-D2 (DFT-D2) method. The results showed that the two layers of TiC(111) coating with the C/C-terminated interfaces were thermodynamically more favorable than one or three layers of TiC(111) on the SiC(0001[combining macron]). Furthermore, the bonding of the Ti-hollow-site stacked interfaces would be a stronger link than that of the Ti-Fcc-site stacked interfaces. However, the formation of the C/Ti/C and Ti/C interfaces implied that the first upper carbon layer can be formed on TiC(111)/SiC(0001[combining macron]) using the decomposition of the weaker Ti-C and C-Si interfacial bonds. When growing graphene layers on these TiC(111)/SiC(0001[combining macron]) substrates, the results showed that the interaction energy depended not only on the thickness of the TiC(111) interlayer, but also on the number of graphene layers. Bilayer graphene on the two layer thick TiC(111)/SiC(0001[combining macron]) was thermodynamically more favorable than a monolayer or trilayer graphene on these TiC(111)/SiC(0001[combining macron]) substrates. The adsorption energies of the bottom graphene layers with the TiC(111)/SiC(0001[combining macron]) substrates increased with the decrease of the interface vertical distance. The interaction energies between the bottom, second and third layers of graphene on the TiC(111)/SiC(0001[combining macron]) were significantly higher than that of the freestanding graphene layers. All of these findings provided insight into the growth of epitaxial graphene on TiC(111)/SiC(0001[combining macron]) substrates and the design of graphene/TiC/SiC-based electronic devices.

It is a complex coupling of multi-physics field for metal deformed flow behavior under the condition of adhesive friction, which has been studied in this paper. In this paper, ring upsetting has been carried out with various press amounts. By comparisons of the transient displacement figure of internal & external metal particles under different press quantities, deformed flow state of metal particles is obtained, and inverse flow is found under the adhesive friction. Based on transient displacement obtained by ring upsetting, the flow orientation of the whole specimen is specifically acquired by means of piecewise cubic hermite polynomial interpolation. In the end, representation model of deformed flow behavior is put forward to illustrating and predicting the flow behavior of metal particles.

Many in vitro studies focus on effects of wall shear stress (WSS) and wall shear stress gradient (WSSG) on endothelial cells, which are linked to the initiation and progression of atherosclerosis in the arterial system. Limitation in available flow chambers with a constant WSSG in the testing region makes it difficult to quantify cellular responses to WSSG. The current study proposes and characterizes a type of converging parallel plate flow chamber (PPFC) featuring a constant gradient of WSS. A simple formula was derived for the curvature of side walls, which relates WSSG to flow rate (Q), height of the PPFC (h), length of the convergent section (L), its widths at the entrance (w0) and exit (w1). CFD simulation of flow in the chamber is carried out. Constant WSSG is observed in most regions of the top and bottom plates except those in close proximity of side walls. A change in Q or h induces equally proportional changes in WSS and WSSG whereas an alteration in the ratio between w0 and w1 results in a more significant change in WSSG than that in WSS. The current design makes possible an easy quantification of WSSG on endothelial cells in the flow chamber.

In this paper, we present a density-method-based model to allocate the refining cost to petroleum products such as gasoline and diesel. By using this model, we also present an empirical study of China, which is based on a virtual crude oil refining process proposed referring to the technical configuration of oil refining industry in China. Three scenarios of the cost of gasoline and diesel are illustrated referring to different settings of the change of the international crude oil prices. The results indicate that the cost of gasoline and diesel change nearly the same amplitude as the change of crude oil price. However, the margin between the cost of gasoline and diesel will slightly increase with the rise of crude oil price. Besides, we also present a sensitivity analysis of the operation cost of each unit in the refining process. The results reveal that the operation cost of catalytic reforming is the most important influencing factor of the cost of gasoline, while the operation cost of hydrogen cracking influences the cost of diesel mostly.

A method which utilizes the power bond graph to establish the flexible hose model is described in this work. By using this method, the paper establishes mathematical modeling for the location of electro-hydraulic proportional control system with the flexible hose. And then, this article completes dynamic simulation by MATLAB and analyses the results of simulation. The effect of the flexible hose parameters on dynamics characteristics of the hydraulic system is also studied.

Describes the working principle of hydraulic system elevator, established the power bond graph and the state equation of the energy release circuit, and the simulation results prove the feasibility of energy release circuit.

Introduced the energy recovery hydraulic elevator system's principle of work, calculated the uplink and the downlink of the hydraulic elevator system's useful work, total power and efficiency, results show that energy-saving effect of the hydraulic system was more obvious.

In competitive petroleum markets, oil price forecasting has always been an important strategic tool for oil producers and consumers to predict market behavior. In this study, we researched the monthly crude oil price in the period between 1988 and 2009. Firstly, we present a state space model to represent oil price system. Secondly, we determine the parameter estimates of the state space model for oil price through a faster algorithm to compute the likelihood function. Lastly, we use the Kalman filter method to estimate the next three months’ oil price and compare it with the econometric structure model as a benchmark. Empirical results indicate that the state space model performs well in terms of some standard statistics indices, and it may be a promising method for short-term oil price forecasting.

Product tolerance is one of the important factors which affect the quality and cost of product. However, influenced by many complicated factors, there are still many problems which need to be resolved compared with other research works in CAD field. How to determine tolerances of product effectively is still a big problem. Based on exponent model of tolerance-cost, the relationships between tolerance and other characteristics influencing processing cost are studied in this paper. A relational model of tolerance-cost is come up with based on the above relationships. And then, internal relation between tolerance and lifetime is discussed. Meanwhile, along with the lifetime converted into the cost, the compensated relational model of tolerance-lifetime is presented. Finally, the method on the decision of tolerance grade is analyzed. This paper realizes the organic combination of tolerance, lifetime and cost, and effectively decides how to generate tolerance grades.

Use of hydrogen as a temporary alloying element in Ti alloys is an attractive approach to improve the mechanical properties of the materials, enhance processability and thereby reduce manufacturing costs. In this paper, the hydrogen diffusion process and the phase transformation both between Ti particles and in Ti sheets were simulated to analyze the mechanism of hydrogen diffusion in different phases (α-Ti, β-Ti and TiHx). With the simulation based on the kinetics and thermodynamics, quantitative behaviors of the hydrogen diffusion and the phase transformation were analyzed. The simulation results provide an insight into the diffusion process and improve the fundamental understanding of the mechanism of diffusion and phase transformation.

A novel iron-catalyzed aminolysis of β-carbonyl 1,3-dithianes with various amines including ammonia, primary and secondary amines, as well as hydrazine hydrate has been developed, leading to the synthesis of stereodefined β-enaminones and 3,4-disubstituted pyrazoles in good to high yields.

The Ni bis-dithiolene complexes with D2h symmetry were predicted to be stable at B3LYP/6-311++G(d) level. The analyses of nature bond orbital and nucleus-independent chemical shift (NICS) at B3LYP/6-31G(d) and GIAO-B3LYP/6-31G(d) level revealed the aromatic character of the Ni bis-dithiolene complexes. The total isotropic NICS (NICSiso) at the ring center [NICS(0)iso] has main contribution from the molecular orbitals (MOs) within the molecular plane according to the analysis of canonical MO (CMO) contributions to NICS. The π MOs have large contribution to the NICSiso at 1 A above the ring center [NICS(1)iso]. Both analyses of CMO and nature local MO (NLMO) predict that the Ni–S σ bonds weaken the aromaticity of the Ni(S2C2H2) and Ni(bdt)2 complexes. The three d atomic orbitals with lone pair electrons of the Ni atom and the delocalized π bond among S–C–C–S have large contribution to the NICS(0)iso and NICS(1)iso in Ni(S2C2H2) and Ni(bdt)2 according to the analyses of NLMO. The C–C π bond has large contribution to the NICS(n)iso (n = 0 or 1) in Ni(S2C2H2)2, while the delocalized S–C π bond has large contribution to the NICS(n)iso (n = 0 or 1) in Ni(bdt)2.

Ab initio calculations show that, for the P n( CH )4-n PH with n = 0 - 4, the fully optimized structures have decreasing pyramidality at the tri-coordinated phosphorus atom with n. The interaction between the tri-coordinated phosphorus [Formula: see text] and the carbons–phosphorus π-system [Formula: see text] with different n, the differences of the structure, electron properties and energy among the phospholes indicate that the ring strain and the delocalization of the lone pair electron of tri-coordinated phosphorus should be responsible for this phenomena. Various aromatic criteria such as geometry, magnetism, and energy show that these molecules are aromatic, and their aromaticities increase with the number of phosphorus atoms in the nonplanar pentagons. The electron circulation in the aromatic molecules can promote the delocalization of the lone pair. In contrast to the B3LYP prediction, we draw some similar conclusions, but the planarity and aromaticity of molecules increase largely at the MP2 lever due to the consideration of electron correlation.

Four new phenylpropanoid esters of rhamnose, asiatisides A-D, along with the known compounds, buergeriside C(1) (5), p-methoxycinnamic acid, ferulic acid, and O-methylferulic acid were obtained from the aerial parts of Buddleja asiatica LOUR by chromatographic methods. The new compounds were elucidated as 3-O-acetyl-4-O-(p-methoxycinnamoyl)-alpha-L-rhamnopyranose (1), 3-O-acetyl-4-O-feruloyl-alpha-L-rhamnopyranose (2), 2-O-acetyl-4-O-(O-methylferuloyl)-alpha-L-rhamnopyranose (3), 2-O-acetyl-4-O-(p-methoxycinnamoyl)-alpha-L-rhamnopyranose (4) by spectral data (1D-, 2D-NMR, and MS), respectively.

Two new oleanane-type triterpenoids, 13,28-epoxy-23-hydroxy-11-oleanene-3-one (1) and 13,28- epoxy-21β ,23-dihydroxy-11-oleanene-3-one (2), along with seven known compounds, have been isolated from the aerial parts of Buddleja asiatica Lour. All structures were elucidated by spectroscopic techniques (NMR, MS, UV, and IR).

SummaryIntroduction: Detection of the V600E hotspot mutation in BRAF oncogene is extremely useful for the screening of hereditary non-polyposis colorectal cancer (Lynch's syndrome) and for the prediction of sensitivity to MEK inhibitors. Here we describe a method for detecting this mutation based upon pyrosequencing technology.Methods: The efficiency of pyrosequencing for detecting BRAF V600E mutations was compared with the conventional dideoxy sequencing method in 12 tumour cell lines and in 108 colorectal tumours.Results: The results from pyrosequencing were 100% concordant with those from dideoxy sequencing. This method was capable of detecting BRAF V600E mutations at a much lower ratio of mutant to wild-type alleles (1:50) than dideoxy sequencing (1:5) while being considerably faster and less expensive.Conclusions: Pyrosequencing offers a specific, sensitive, rapid and cost-effective alternative to dideoxy sequencing for the detection of BRAF V600E mutations in clinical tumour specimens.

The phosphorus analogues (phosphanyl ketones) of pyridones are shown by theory to exhibit qualitatively different structures. Energy minimum of meta-phosphanyl ketone is planar while the planar conformations of the ortho- and para-isomers are transition state. Analysis of the electron density using the electron localization function (ELF) rationalizes the structural differences. In these molecules, there are competitive effects on geometry due to the octet rule, electron delocalization, and pyramidality of the tri-coordinated nitrogen or phosphorus. A delicate balance determines the molecular conformations.

Structures and magnetic properties [nucleus independent chemical shifts (NICS)] of [M2(η5–P5)2] and [M(η5–P5)2] (M = Be, Mg, and Ca) are studied with density functional theory at B3LYP level using the 6-311+G(d, p) basis sets. The M 2 2 + and M2+ sandwich complexes with D5 symmetry are minima. The D5h and D5d symmetry conformations are saddle points on the flat potential energy surface. Analyses of molecular orbital correlation and binding energy for the two series of complexes reveal that the M–M bond is a weak σ covalent bond. In addition to electrostatic interactions, there are also covalent bonds between the M and the P 5 - ring. The M–M bond plays a dominant role in the stability of both series of complexes. The M–M and M–P5 bond strength decreases as M varies from Be to Ca. The P–P bond length in these complexes is slightly elongated with respect to that in P 5 - . The NICS computed with GIAO-B3LYP/6-311+G(d,p) indicates that the P5 rings in both series of complexes are aromatic, and the aromaticity decreases as M varies from Be to Ca. In these complexes, the NICS at the P5 ring center slightly decreases and it increases at the outer side of the P5 ring, thus resulting in the elongation of P–P bond and the significant flow of π-electron from the ring towards the bonding of the P5 ring with the M 2 2 + unit or M and leading to the strengthening of the M–P5 bonding. The dissected NICS of the P 5 - ring of these complexes shows that the large total NICS is mainly due to the P–P π bond contribution of the P5 ring. The NICS of the P–P π bond decreases as the metal varies from Be to Ca.

Some η5-cyclopentadienyl cobalt dithiolene complexes CpCoS2C2R2 have been optimized at B3LYP/6-311++G(d) level. The optimized geometries agree well with experiment. The analyses of nature bond orbital and nucleus-independent chemical shift (NICS) at B3LYP/6-311++G(d) and GIAO-B3LYP/6-311++G(d) levels reveal the aromatic character of the η5-cyclopentadienyl cobalt dithiolene complexes. However, their aromaticity is weaker than that of the isolated CoS 2 C 2 + 1 . There are two reasons for the change of heterocyclic aromaticity of the metal dithiolene in the η5-cyclopentadienyl cobalt dithiolene complexes with respect to that of the isolated CoS 2 C 2 + 1 . The better equalization of bond lengths in the isolated cation CoS 2 C 2 + 1 is the first reason. The other reason is that the contribution to the NICS from the metallic cobalt atom is much larger in the isolated cation CoS 2 C 2 + 1 . The planar character of cyclopentadienyl is destroyed slightly in the complexes. At the same time, the size of cyclopentadienyl (Cp) becomes bigger than the isolated Cp−1 and this is caused by the cobalt atom in the pentagon. The π-electron delocalization causes stronger aromaticity of the Cp in the complexes than that of the isolated Cp−1.