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The polymerization mechanism of functionalized styrene derivatives, viz., p-NMe2 (pMNS)-, o-/p-OCH3 (o/pMOS)-, and p-SCH3 (pMTS)-substituted styrene, catalyzed by cationic rare-earth-metal catalysts has been comparatively studied through density functional theory (DFT) calculations. Having achieved an agreement between theory and experiment, it is found that large steric hindrance as a main factor prevents oMOS from undergoing o-C–H activation relevant to step-growth polymerization, while the nonoccurrence of C–H activation of pMNS and pMTS can be explained by the relatively less dispersion of charge distribution in the four-center transition states. In addition, the electron-donating pyridine side arm weakened the interaction between pMOS and the metal center and meanwhile increased the steric hindrance, preventing the C–H activation. Therefore, the simultaneous occurrence of C–H activation (step-growth polymerization) and C═C insertion (chain-growth polymerization) are affected by multiple factors such ...

Multisite phosphorylation of a protein, generally occurring in biological processes, plays important roles in the regulation of cellular functions. However, the identification of multi-phosphopeptides especially at low abundance is a big challenge as the extreme hydrophilicity and poor ionization efficiency of the multiphosphorylated peptides restrict the deep inspection of multisite phosphorylation processes. In this study, the highly specific enrichment of multiphosphorylated peptides was achieved via the modification of the dual-metal-centered zirconium-organic framework with the diphosphorylated fructose. The diphosphorylated fructose-modified dual-metal-centered zirconium-organic framework (DZMOF-FDP) demonstrated the highly specific affinity to the multiple phosphorylated peptides, with the density functional theory calculations explaining the plausible mechanism for multi-phosphopeptides on the DZMOF-FDP. The selective capture of multi-phosphopeptides from mimic samples confirmed the superior performance of the DZMOF-FDP, with comprehensive comparisons to other modification agents, such as orthophosphate and pyrophosphate. A number of 1871 multiphosphorylated peptides captured by DZMOF-FDP from tryptic digests of HeLa cell lysate could be identified, significantly higher than that by the pristine DZMOF. The deliberately designed modification with diphosphorylated fructose for the dual-zirconium-centered metal-organic framework materials suggests an efficient strategy to develop new enrichment methods in the selective capture of target analytes by judiciously optimizing specific modifiers for adsorbents.

DFT studies have been conducted for the direct benzylic C(sp3)–H alkylation of alkylpyridines with olefins catalyzed by a cationic half-sandwich yttrium alkyl complex. It has been found that, in th...

Density functional theory studies have been conducted for isoprene polymerization catalyzed by the cationic half-sandwich scandium alkyl species containing a methoxy side arm [(C5Me4C6H4OMe-o)Sc(CH2SiMe3)]+ (1) and that containing a phosphine oxide side arm [{C5Me4SiMe2CH2P(O)Ph2}Sc(CH2SiMe3)]+ (2). It has been found that trans-1,4-polymerization of isoprene by species 1 prefers an insertion–isomerization mechanism: (i) an insertion of cis-isoprene into the metal–alkyl bond to give η3-π-anti-form, (ii) anti-syn isomerization of the resulting 1,2-disubstituted allyl complex to yield a syn-allyl form, (iii) repetitive insertion of cis-isoprene into the metal–syn-allyl bond and subsequent anti–syn isomerization. The resulting η3-π-syn-allyl species is suitable for more kinetically favorable cis-monomer insertion. The stability of the key transition state involved in the most feasible pathway could be ascribed to the smaller deformation of cis-isoprene and stronger interaction between the cis-isoprene moiety ...

Mitochondrial dysfunction is a major factor in nonalcoholic fatty liver disease (NAFLD), preceding insulin resistance and hepatic steatosis. Carnosol (CAR) is a kind of diterpenoid with antioxidant, anti-inflammatory and antitumor activities. Peroxiredoxin 3 (PRDX3), a mitochondrial H2O2-eliminating enzyme, undergoes overoxidation and subsequent inactivation under oxidative stress. The purpose of this study was to investigate the protective effect of the natural phenolic compound CAR on NAFLD via PRDX3. Mice fed a high-fat diet (HFD) and AML-12 cells treated with palmitic acid (PA) were used to detect the molecular mechanism of CAR in NAFLD. We found that pharmacological treatment with CAR notably moderated HFD- and PA- induced steatosis and liver injury, as shown by biochemical assays, Oil Red O and Nile Red staining. Further mechanistic investigations revealed that CAR exerted anti-NAFLD effects by inhibiting mitochondrial oxidative stress, perturbation of mitochondrial dynamics, and apoptosis in vivo and in vitro. The decreased protein and mRNA levels of PRDX3 were accompanied by intense oxidative stress after PA intervention. Interestingly, CAR specifically bound PRDX3, as shown by molecular docking assays, and increased the expression of PRDX3. However, the hepatoprotection of CAR in NAFLD was largely abolished by specific PRDX3 siRNA, which increased mitochondrial dysfunction and exacerbated apoptosis in vitro. In conclusion, CAR suppressed lipid accumulation, mitochondrial dysfunction and hepatocyte apoptosis by activating PRDX3, mitigating the progression of NAFLD, and thus, CAR may represent a promising candidate for clinical treatment of steatosis.

The mechanisms of H–H and N–H bond cleavages of dihydrogen and ammonia mediated by the diiridium μ2-imido complex [(Cp*Ir)2(μ2-H)(μ2-NH)]+ (A; Cp* = η5-C5Me5) were theoretically investigated with the density functional theory (DFT) method. Both oxidative addition and metal–ligand cooperation modes have been studied for H–H and N–H bond cleavages, respectively. The H–H bond cleavage most likely occurs through competitive oxidative addition and metal–ligand cooperation, and both cleavage modes have similar overall free energy barriers (24.3 and 25.7 kcal/mol, respectively). The ligand-assisted N–H bond heterolytic cleavage mechanism is proposed for the NH3 reaction, and the general oxidative addition pathway can be reasonably ruled out, as it is kinetically unfavorable.

Aims To investigate the antitumor effects of 7-O-geranylquercetin (GQ), a novel O-alkylated derivative of quercetin, against non-small cell lung cancer (NSCLC) cell lines A549 and NCI-H1975 and the corresponding mechanisms. Main methods Cell viability was assessed using MTT assay. The expression of proteins involved in apoptosis and autophagy was measured using western blotting. Besides, apoptosis was determined with DAPI staining, Annexin V-PI staining and transmission electron microscopy (TEM) assay, and autophagy was observed with TEM assay. Cell cycle and reactive oxygen species (ROS) level were detected using flow cytometry. Key findings GQ inhibited viability of A549 and NCI-H1975 cells in a dose- and time-dependent manner without apparent cytotoxicity to normal human lung fibroblast cells. GQ down-regulated the expression of apoptosis-related proteins pro-caspase 3 and Bcl-2, and up-regulated the expression of cleaved-PARP and Bax in A549 and NCI-H1975 cells. Meanwhile, GQ-induced cell apoptosis could be attenuated by caspase inhibitor Z-VAD-FMK. Besides, GQ induced autophagosome formation in A549 and NCI-H1975 cells, promoted the expression of autophagy-related proteins LC3-II and Beclin 1, and suppressed the expression of p62. Autophagy inhibition with chloroquine or Beclin 1 siRNA could effectively inhibit GQ-induced apoptosis. Furthermore, GQ treatment increased the generation of ROS, and ROS inhibitor N-acetylcysteine could reverse GQ-induced autophagy and apoptosis. Taken together, GQ could induce apoptosis and autophagy via ROS generation in A549 and NCI-H1975 cells, and GQ-induced autophagy contributed to apoptosis. Significance Our findings highlight that GQ is a promising anticancer agent for the treatment of lung cancer.

An organic-silica hybrid monolithic capillary column was fabricated by crosslinking (3-aminopropyl)trimethoxysilane (APTMS) modified mesoporous carbon nanoparticles (AP-MCNs) with tetramethoxysilane (TMOS) and n-butyltrimethoxysilane (C4-TriMOS). Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy, mercury intrusion porosimetry and inverse size-exclusion chromatography characterization proved the successful immobilization of mesoporous carbon nanoparticles (MCNs). The crosslinking of AP-MCNs into the hybrid monolithic matrix has significantly increased the reversed-phase retention of alkylbenzenes and chromatographic performance for small molecules separations in comparison with the neat one without MCNs. The resulting column efficiency of the mesoporous carbon nanoparticle-based butyl-silica hybrid monolithic column (MCN-C4-monolith) was up to ca. 116,600 N/m for the capillary liquid chromatography (cLC) separation of butylbenzene. Enhanced performance of proteins separation was achieved on the MCN-C4-monolith in comparison with the butyl-silica hybrid monolithic column without MCN (C4-monolith). The separation of peptides from bovine serum albumin (BSA) digest was carried out on the MCN-C4-monolith by capillary liquid chromatography–tandem mass spectrometry (cLC–MS/MS) with protein sequence coverage of 81.9%, suggesting its potential application in proteomics.

The isoprene/ethylene copolymerization catalyzed by cationic rare earth metal complexes [(η5-C5Me5)Sc(CH2SiMe3)]+ (A) had afforded alternating isoprene-ethylene copolymer with rich 3,4-polyisoprene microstructures, whereas no isoprene-ethylene copolymer was observed by using analogous [(PNPPh)Sc(CH2SiMe3)]+ (B) under the same conditions. Theoretical calculations in this work have revealed that, in the case of A, successive 3,4-insertion of isoprene resulted in a noncovalent interaction between the C = C double bond of penultimate unit and the metal center, suppressing the further insertion of monomers due to higher energy barrier and endergonic character. On the other hand, the ethylene pre-inserted species with alkyl active site is more suitable for the subsequent kinetically and thermodynamically favorable isoprene insertion and copolymerization is therefore realized. In the case of B, the experimentally observed cis-1,4-specific homopolymerization of isoprene was the outcome of both kinetic and thermodynamic control. And, the unfavorable ethylene insertion into the isoprene pre-inserted species with allyl active site could account for the experimental finding that no isoprene-ethylene copolymer was obtained. These computational results are expected to provide some hints for the design of rare earth copolymerization catalysts.

Background and purpose Hepatic fatty acid metabolism disorder, a key pathogenic mechanism underlying non-alcoholic fatty liver disease (NAFLD), is associated with the hyperacetylation of mitochondrial enzymes. Acyl-CoA synthetase family member 3 (ACSF3), which is involved in the regulation of fatty acid metabolism, was predicted to contain lysine acetylation sites related to the mitochondrial deacetylase sirtuin 3 (SIRT3). The purpose of this study was to explore the underlying mechanism by which SIRT3 deacetylates ACSF3 in NAFLD and the protective effect of the natural phenolic compound protocatechuic acid (PCA) against fatty acid metabolism disorder via the SIRT3/ACSF3 pathway. Experimental approach The role of protocatechuic acid and its molecular mechanism in NAFLD were detected in rats and SIRT3-knockout mice fed a high-fat diet (HFD) and in AML-12 cells treated with palmitic acid (PA). Key results Pharmacological treatment with protocatechuic acid significantly attenuated high-fat diet-induced fatty acid metabolism disorder in NAFLD. Molecular docking assays showed that protocatechuic acid specifically bound SIRT3 as a substrate and increased SIRT3 protein expression. However, the protective role of protocatechuic acid was abolished by SIRT3 knockdown, which increased ACSF3 expression and exacerbated fatty acid metabolism disorder. Mechanistically, SIRT3 was shown to specifically regulate the acetylation and degradation of ACSF3, which govern the capacity of ACSF3 to mediate fatty acid metabolism disorder during NAFLD. Conclusion and implications SIRT3-mediated ACSF3 deacetylation is a novel molecular mechanism in NAFLD therapy and protocatechuic acid confers protection against high-fat diet- and palmitic acid-induced hepatic fatty acid metabolism disorder through the SIRT3/ACSF3 pathway.

DFT calculations disclosed that the stereoselectivity of Sc-catalysed polymerization of halogenated styrenes could be co-regulated via C–H⋯π interactions between a coordinating THF and the phenyl ring of a monomer. Such a regulatory mechanism was theoretically confirmed by further studying the polymerization of various monomers, where the stereoselectivity could even shift from syndiotacticity to isotacticity.

With semiconductor technology progressing beyond 5nm node, there is tremendous pressure on computational lithography to achieve both accuracy and speed. One very promising technique to accomplish this mission is to take full advantage of the maturing machine learning techniques based on neural network architecture. Some success has been achieved using convolution neural network (CNN) to obtain inverse lithography technology (ILT) solution with significantly less computational time. In general, CNN architecture consists of feature extraction layers and nonlinear mapping function construction layers. To train a CNN model requires a large amount of data and computational resource. To maintain certain intrinsic symmetries of imaging behavior, the feature extraction layers must be carefully engineered using weight sharing techniques or using well balanced training samples of different orientations, otherwise, feature extraction part will be skewed. It is therefore very desired to have a scheme that can obtain optimal feature vector for machine learning based computational lithography automatically without the need of feature extraction layers in CNN. In this paper, we will make an attempt to describe such a scheme and present our test results on machine learning based OPC and ILT solution. It should be understood that machine learning based computational lithography solutions do not possess the capability to replace conventional OPC or ILT completely due to its lack of required accuracy. However, it can provide an initial solution that is close enough to final OPC solution or ILT solution, therefore fast OPC and fast ILT can be realized.

This chapter reviews recent advances in computational methods for olefin copolymerizations catalyzed by organo rare-earth metal complexes. On the basis of theoretical identified polymerization mechanisms, the effects of several factors such as activity and regio- and stereo-selectivity on the polymerizations are explained. This knowledge provides a better understanding of experimental observations, and also offers insights for the design of new rare-earth metal polymerization catalysts. Computational studies on heteroatom-containing olefin copolymerization are also reviewed. Commonly-used density functional theory (DFT)-based methods and computational strategies that are suitable for modeling the rare-earth-metal catalyzed olefin polymerization are introduced. The studies summarized herein also demonstrate that DFT-based methods, together with an experimentation, represent an effective and promising strategy for elucidating polymerization mechanisms and further developing new catalytic polymerization systems.

The toxicology of cationic liposomes was explored to advance clinical trials of liposome-mediated gene therapy through the analysis of a peptide cationic liposome with DOTAP as a positive control. We first investigated the delivery of luciferase siRNA by several peptide liposomes in mice bearing lung cancer A549 cell xenografts. Of these, a cationic liposome (CDO14) was selected for further investigation. CDO14 efficiently mediated IGF-1R-siRNA delivery and inhibited the growth of the A549 cell xenografts. The in vivo toxicity and toxicological mechanisms of the selected liposome were evaluated to assess its potential utility for gene delivery. Specifically, the effects of CDO14 on mouse body weight, hematology, urine, serum biochemical indices, and histopathology were measured in acute toxicity and subchronic toxicity tests. CDO14 showed limited toxicological effects at low dosages although it induced pulmonary inflammation and liver injury at higher dosages. The toxicity of CDO14 was lower than that of DOTAP, and the toxicity of CDO14 did not change when complexed with siRNA. The pulmonary inflammation induced by CDO14 occurred via expressional up-regulation of the pro-inflammatory cytokines TNF-α and IL-6, and expressional down-regulation of the anti-inflammatory cytokine IL-10. Liver injury induced by CDO14 was mediated by the JAK2-STAT3 signaling pathway. Lastly, CDO14 did not affect the expression of apoptosis-related proteins in normal liver cells, suggesting that it did not induce apoptosis of normal cells. The toxicological results demonstrate that peptide-based headgroups in lipids are superior to those with quaternary ammonium headgroups that are used as gene vectors for cancer therapy.

The regioselective polymerizations of isoprene and 3-methyl-pentadiene catalyzed by a cationic iron (II) complex bearing bipyridine ligand have been computationally studied. Having achieved an agreement between calculation and experiment, it is found that the open-shell unpaired 3d-electrons localize on Fe center rather than partially distribute on the redox-active bipyridine ligand. The steric effect plays a more important role in controlling the regioselectivity in comparison with electronic factors. The deformation energy is mainly contributed by monomer and Fe-alkyl moieties rather than the bipyridine ligands themselves, although noncyclopentadienyl ancillary ligands are often deformed in most insertion transition states for selective polymerization of olefin. © 2016 Wiley Periodicals, Inc.

The effect of alkyls on the chain initiation efficiency of ethylene, propene, 1-hexene, styrene, butadiene, and isoprene polymerizations catalyzed by the half-sandwich cationic rare-earth-metal alkyl complexes [(η5-C5Me5)ScR]+ (R = CH2SiMe3, 1; R = o-CH2C6H4NMe2, 2; R = η3-C3H5, 3) has been studied by using a DFT approach. It has been found that 2 with the largest sterically demanding aminobenzyl group results in the lowest initiation efficiency and thus longest induction period among the three catalysts investigated. In contrast, 1 with CH2SiMe3 displays the best chain initiation ability, and 3 with η3-allyl gives moderate chain initiation activity, mainly due to the most stable resulting coordination complex. Species 1 and 3 have better regioselectivity in the chain initiation of styrene polymerization than species 2. In addition, species 1′ ([(η5-C5Me5)Sc(CH2SiMe3)THF]+) with a THF ligand has better chain initiation efficiency in styrene and isoprene polymerizations than species 2 but is reasonably wor...

The reaction of a half-sandwich scandium boryl complex 1 with CO (1 atm) afforded a novel boryl oxycarbene complex 2. The structure of 2 was characterized by 1H, 13C and 11B NMR, X-ray diffraction, and DFT analysis. Further reaction of 2 with CO (1 atm) yielded a phenylamido- and boryl-substituted enediolate complex 3 through C–C bond formation between CO and the carbene unit in 2 and cleavage and rearrangement of the Si–N bond in the silylene-linked Cp–amido ligand. Upon heating, insertion of the carbene atom into a methine C–H bond in the boryl ligand of 2 took place to give an alkoxide complex 4. The reactions of 2 with pyridine and 2-methylpyridine led to insertion of the carbene atom into an ortho-C–H bond of pyridine and into a methyl C–H bond of 2-methylpyridine, respectively. The reaction of 2 with ethylene yielded a borylcyclopropyloxy complex 7 through cycloaddition of the carbene atom to ethylene.

The styrene polymerizations catalyzed by cationic half-sandwich rare-earth metal complexes [(η5-C5Me5)Sc(CH2SiMe3)(THF)n]+ (n = 0 (A), 1 (thfA)), [(η5-C5Me5)Sc(CH2C6H4NMe2-o)]+ (B), and [(η5-C5Me5)Sc(C6H4OMe-o)]+ (C) have been computationally studied. It has been found that THF as an external Lewis base has no effect on the regioselectivity in the chain initiation step. However, it can make activity lower toward styrene insertion. THF is computationally proposed to move away from the Sc center during chain propagation and thus has no effects on stereoselectivity. Aminobenzyl as an internal Lewis base in B results in no regioselectivity at the chain initiation stage and has no effect on syndioselectivity during chain propagation. The internal Lewis base anisyl induces high-isotactic chain-end microstructure. The discrepancy in chain-end microstructures induced by aminobenzyl and anisyl groups could be ascribed to the different coordination capability of oxygen and nitrogen atoms to Sc metal. The size of th...

Hydrogen sulfide (H2S), as the third multifunctional signaling biomolecule, it acts as a neuromodulator in the human brain and is recognized as an important gas transmitter in human physiology. The abnormal concentrations of H2S in human cells can result in several common diseases. Therefore, accurate, fast, and reliable methodologies are required for measuring the in vitro and in vivo concentrations of H2S to further investigate its function. In this study, a novel DR-SO2N3 fluorescent probe containing the fluorophore Disperse Red 277 and a sulfonyl azide group was developed and exploited based on the structural characteristic of Disperse Red 277 that contains the active site easily can be attacked by HS-. Therefore, this probe featured two reaction sites that involved the reduction and Michael addition of H2S and exhibited rapid ratiometric fluorescence changes and high selectivity towards H2S with a 619-fold enhancement factor. Further, the density functional theory (DFT)/time-dependent density functional theory (TDDFT) studies are conducted to understand the photophysical properties of DR-SO2N3 and the final product DRHS-SO2NH2, which makes the proposed mechanism more reasonable. Furthermore, the probe was successfully applied for the ratiometric fluorescence imaging of exogenous H2S in living cells.

Macrophage recruitment to the inflammation site is essential for LPS-induced myocarditis, although the underlying mechanism remains elusive. This study was designed to examine the role of the P-AKT2/SPK1 (P-SPK1) and P-MEK/P-ERK signaling cascades in the regulation of macrophage migration and LPS-induced myocarditis. Our data revealed that (1) the P-AKT2/SPK1 (P-SPK1) and P-MEK/P-ERK signaling cascades acted separately in the regulation of macrophage migration; (2) P-AKT2/SPK1 (P-SPK1) played a relatively important role compared to P-MEK/P-ERK cell signaling in LPS-induced macrophage migration; (3) atorvastatin (ATV) inhibited macrophage migration by inhibiting P-AKT2/SPK1 (P-SPK1) cell signaling, but ATV could increase P-MEK and P-ERK protein expression; (4) ATV has a beneficial effect on LPS-induced myocarditis via inhibition of P-AKT2/SPK1-mediated macrophage recruitment, apoptosis, TNFα, IL-1β, and IL-6; (5) ATV-offered protection against LPS-induced myocarditis was eliminated from SPK1-KO mice; (6) SPK1 may play a harmful role in LPS-induced myocarditis. Taken together, our data revealed that SPK1 represents a novel regulating factor for macrophage migration and cardiac protection under LPS-induced myocarditis.

Aims To investigate the effect of 7-O-geranylquercetin (GQ), a derivative of quercetin (Q), on reversing drug resistance in breast cancer MCF-7/ADR cells and reveal the mechanisms related to P-glycoprotein (P-gp). Main methods Cell viability was determined by MTT assay. Accumulation of adriamycin (ADR) in cells was determined by confocal fluorescence microscope and microplate reader while that of rhodamine (Rh) was measured by flow cytometry. Expression levels of P-gp and MDR1 gene in cells were detected by western blot and Real-Time PCR, respectively. Molecular docking of GQ and Q with P-gp was conducted using AutoDock program. Xenograft model was established by inoculating MCF-7/ADR cells in BALB/c-nude mice. Tumor bearing mice were administered with ADR via tail vein injection and/or GQ (Q) by gavage. Expression levels of P-gp in tissues were detected by western blot and immunohistochemistry. Key findings GQ could reverse drug resistance of MCF-7/ADR cells to ADR. GQ inhibited the efflux of ADR by down-regulating the expression of P-gp protein and its encoding gene MDR1 in MCF-7/ADR cells. Molecular modeling showed that GQ matched with P-gp better than Q. GQ enhanced the antitumor effects of ADR and decreased the expression of P-gp in mice and its activities were higher than that of Q. GQ could reverse drug resistance of MCF-7/ADR cells by down-regulating the expression of P-gp in vitro and in vivo. Significances The reversal effect of GQ on P-gp-mediated drug resistance indicates its potential as a reversal agent for drug resistance in cancer chemotherapy.

The combination of siRNAs and chemical drugs for the treatment of tumors has received more and more attention. This study investigated the synergistic effect of 7-O-geranyl quercetin (GQ) and IGF-1R siRNA (siIGF-1R) co-delivered by a liposome on human non-small cell lung cancer (NSCLC). GQ was firstly loaded with cationic liposome CDO14 to form CDO14-GQ which then combined with siIGF-1R to form co-delivery liposome CDO14-GQ-siIGF-1R. CCk-8 assay indicated that CDO14-GQ-siIGF-1R enhanced the anti-proliferation effect of CDO14-GQ or CDO14-siIGF-1R in NCI–H460 and A549 cells, AO/EB and AV/PI staining assays showed that the co-delivery liposome increased the pro-apoptosis effect of CDO14-GQ or CDO14-siIGF-1R. The growth inhibition effect of CDO14-GQ-siIGF-1R on the xenograft of NCI–H460 and A549 cells in mice was much stronger than that of CDO14-GQ or CDO14-siIGF-1R. Western blot assay indicated that CDO14-GQ-siIGF-1R down-regulated the expression levels of siIGF-1R in cells and in tumor tissues, and its effect on the expression of apoptosis-related proteins Bcl-2 and Bax was stronger than that of CDO14-GQ or CDO14-siIGF-1R. These results demonstrated that co-delivery of GQ and siIGF-1R by liposome improved the antitumor effect of either of them. Our study highlight that siRNAs combined with chemotherapeutic drugs is a promising strategy for the treatment of NSCLC.

A novel tri-layered ZnO nanostructure, which consists of ZnO nanowires (ZnO NWs) as the underlayer, small ZnO hierarchical microspheres (S-ZnO HMSs) as the intermediate layer and large ZnO hierarchical microspheres (L-ZnO HMSs) as the overlayer, was designed and studied as the photoanode for dye-sensitized solar cells (DSSCs). The photoanode was characterized by X-ray diffraction, scanning electron microscopy and its optical properties were measured by UV-vis spectrophotometry. The performance of the DSSC based on the photoanode was characterized by the incident-photon-to-current conversion efficiency (IPCE) and voltage–current curve (I–V). The results indicate that ZnO hierarchical microspheres show a good bifunctional character (light scattering effect and dye-loading ability), which causes the corresponding DSSCs based on the tri-layered ZnO photoanode to obtain the highest photovoltaic conversion efficiency (3.21%) compared with the DSSC based on the double layered ZnO photoanode and single layer ZnO NWs photoanode.

Tilletia controversa Kühn (TCK) is an important quarantine pathogen that causes wheat dwarf bunt and results in devastating damage to wheat production. The fungus is difficult to be distinguished from T. caries and T. laevis, which cause wheat common bunt, based on morphological, physiological and symptomatological characteristics of the pathogens. The traditional detection of the fungus can be a long and tedious process with poor accuracy. The inter-simple sequence repeat (ISSR) technique has been used for identifying molecular markers for detection of TCK. Of 28 ISSR primers screened, ISSR-859 amplified a specific 678 bp DNA fragment from all TCK isolates but not from any isolates of the common bunt fungi or other pathogenic fungi tested. Based on the fragment sequence, a pair of sequence characterized amplified region (SCAR) primers was designed, which amplified a 372 bp DNA fragment specifically in TCK. The SCAR marker was detected using as low as 1 ng template DNA of TCK, and was also detected using broken teliospores and DNA from asymptomatic wheat samples. We developed the SYBR Green I and TaqMan Green I and TaqMan real-time polymorphism chain reaction methods to detect TCK with the detection limit of 0.1 fg with asymptomatic wheat samples. Further work is needed to develop a rapid test kit for this pathogenic fungus using the designed specific primers.

This paper reports a DFT study on trans-1,4-specific polymerization of isoprene catalyzed by the cationic heterobimetallic half-sandwich complex [(C5Me5)La(AlMe4)]+. The possible structures of the active species, viz., [(C5Me5)La(μ2-Me)3AlMe]+ (A), [(C5Me5)La(μ2-Me)2AlMe2]+ (B), and [(C5Me5)La(Me)(μ2-Me)AlMe2]+ (C), have been investigated. On the basis of the chain initiation and the structure transformations among these three species, C has been proposed to be the true active species smoothly producing trans-1,4-polyisoprene observed experimentally. Both La/Al bimetal-cooperating monomer insertion and La-center-based insertion pathways have been calculated, and the latter is found to be more favorable, where the AlMe3 moiety serves as a ligand coordinating to the La center via a methyl group. In contrast to this, in the Y analogous system, the AlMe3 ligand is proposed to leave away from the Y center during the chain propagation and the cis-1,4-selectivity is preferred, showing a consistence with experime...

The reaction of rare-earth bis(alkyl) complexes containing a bis(phosphinophenyl)amido pincer (PNP), LnPNPiPr(CH2SiMe3)2 (1-Ln, Ln = Y, Ho, Dy), with ruthenium trihydride phosphine complexes, Ru(C5Me5)H3PPh3 and Ru(C5Me5)H3PPh2Me, gave the corresponding bimetallic Ln/Ru complexes bearing two hydride ligands and a bridging phosphinophenyl (μ-C6H4PPh2-κP:κC1, 2a-Ln) or a bridging phosphinomethyl ligand (μ-CH2PPh2-κP:κC, 2b-Ln), respectively. Reaction of 2a-Y with CO gas at 1 atm and at 20 °C in toluene-d8 afforded the complex 3a-Y, which bears a bridging pseudooxymethylene ligand (μ-OCH(o-C6H4)PPh2-κP:κO) and a bridging hydride ligand on the Y/Ru centers. Computational studies by the DFT method suggested that 3a-Y was formed in two steps: first the coordination of CO (ΔG(B3PW91) = 22.9; ΔG(M06) = 14.9 kcal/mol) and migratory insertion of the Y–C6H4 group (ΔG⧧(B3PW91) = 13.3; ΔG⧧(M06) = 16.7 kcal/mol), followed by a rapid intramolecular hydride migration to the resulting acyl group. Complex 2b-Y reacted with...

Titanium Cleaver A century after its discovery, the Haber Bosch process is still used to produce ammonia from nitrogen for fertilizer. Nonetheless, the process requires high temperature and pressure, and chemists continue to look for synthetic analogs to microbial nitrogenase enzymes, which have managed to slice through the N2 triple bond under ambient conditions for millennia. Most efforts in this vein have relied on a boost from the reducing power of alkali metals. Shima et al. (p. 1549 ; see the Perspective by Fryzuk ) instead explored the reactivity of a titanium hydride cluster, which cleanly slices through N 2 at room temperature and incorporates the separated N atoms into its framework. Though ammonia was not produced, the system offers hope in the search for mild nitrogen reduction catalysts.

The interactions between trypsin and caffeine/theophylline were investigated by fluorescence spectroscopy, UV–visible absorption spectroscopy, resonance light scattering and synchronous fluorescence spectroscopy under mimic physiological conditions. The results revealed that the fluorescence quenching of trypsin by caffeine and theophylline was the result of the formed complex of caffeine–trypsin and theophylline–trypsin. The binding constants and thermodynamic parameters at three different temperatures were obtained. The hydrophobic interaction was the predominant intermolecular forces to stabilize the complex. Results showed that caffeine was the stronger quencher and bound to trypsin with higher affinity than theophylline.

The interactions between pepsin and four alkaloids, including caffeine (Caf), aminophylline (Ami), acefylline (Ace), diprophylline (Dip), were investigated by fluorescence, UV–visible absorption, resonance light scattering, synchronous fluorescence spectroscopy and 3D spectroscopy under mimic physiological conditions. The results revealed that Caf (Ami/Ace/Dip) caused the fluorescence quenching of pepsin by the formation of Caf (Ami/Ace/Dip)-pepsin complex. The binding constants and thermodynamic parameters at three different temperatures, the binding locality and the binding power were obtained. The hydrophobic and electrostatic interactions were the predominant intermolecular forces to stabilize the complex. Results showed that aminophylline was the stronger quencher and bound to pepsin with higher affinity than other three alkaloids.

Carbon-carbon bond cleavage of benzene by transition metals is of great fundamental interest and practical importance, as this transformation is involved in the production of fuels and other important chemicals in the industrial hydrocracking of naphtha on solid catalysts. Although this transformation is thought to rely on cooperation of multiple metal sites, molecular-level information on the reaction mechanism has remained scarce to date. Here, we report the DFT studies of the ring cleavage and contraction of benzene by a molecular trinuclear titanium hydride cluster. Our studies suggest that the reaction is initiated by benzene coordination, followed by H2 release, C6H6 hydrometalation, repeated C-C and C-H bond cleavage and formation to give a MeC5H4 unit, and insertion of a Ti atom into the MeC5H4 unit with release of H2 to give a metallacycle product. The C-C bond cleavage and ring contraction of toluene can also occur in a similar fashion, though some details are different due to the presence of the methyl substituent. Obviously, the facile release of H2 from the metal hydride cluster to provide electrons and to alter the charge population at the metal centers, in combination with the flexible metal-hydride connections and dynamic redox behavior of the trimetallic framework, has enabled this unusual transformation to occur. This work has not only provided unprecedented insights into the activation and transformation of benzene over a multimetallic framework but it may also offer help in the design of new molecular catalysts for the activation and transformation of inactive aromatics.

1-Hexene polymerization catalyzed by dicationic rare earth metal alkyl species [Ln(iPr-trisox)(CH2SiMe3)]2+ (Ln = Sc and Y; trisox = trisoxazoline) has been computationally studied by using QM/MM approach. It has been found that the initiation of 1-hexene polymerization kinetically prefers 1,2-insertion (free energy barrier of 17.23 kcal/mol) to 2,1-insertion (free energy barrier of 20.05 kcal/mol). Such a preference of 1,2-insertion has been also found for chain propagation stage. The isotactic polymerization was computed to be more kinetically preferable in comparison with syndiotactic manner, and the dicationic system resulted in lower insertion free energy barrier and more stable insertion product in comparison with the monocationic system. The stereoselectivity was found to follow chain-end mechanism, and the isospecific insertion of 1-hexene is mainly controlled by kinetics. In addition, the current computational results, for the first time, indicate that the higher activity of Sc species toward 1-h...

In real world, social networks are large scale, noisy and evolutionary. Communities are inherent characteristics of human interaction in social networks. Tracking evolutionary communities in dynamic social networks has become an increasingly important research topic. Several classic incremental clustering and evolutionary clustering algorithms have been proposed. But they all face a problem of controlling the balance between running time and clustering quality. In this paper, we propose a fast incremental community evolution tracking (FICET) framework to discover community and track community evolution in slowly and highly evolving networks. For higher clustering quality, this framework identifies community not only by the current network data but also by the prior community structures. For shorter running time, this framework uses subgraph-by-subgraph incremental method, and introduces core sub-graph to infer the core community. Through the introduction of core sub-graph, we can quickly capture the community evolutionary events including forming, dissolving, evolving and so on. Experiments on a series of synthetic datasets and real-world datasets demonstrate that this framework improves both the clustering quality and the time cost when compared with the state-of-the-art frameworks.

This chapter evaluates the stability of the Huanglashi landslide in the Three Gorges of the Yangtze River. By means of the uncertainty evaluation model for the Huanglashi landslide, this chapter calculates and evaluates the stability of the landslide at present and after water storage, and then analyzes the stability after the completion of the Three Gorges project. The stability analysis can be used for predicting the stability tendency and the prevention of future disasters.

The use of Alternating phase-shifting mask has been demonstrated to be a most powerful approach to expand resolution limitation and expand the process window of lithography. But the phase conflict problem limits the application of alt-PSM. For dark field alt-PSM, node connection PSM is a feasible method to solve the problem. We investigate the application of this method at 100nm node by simulation with ArF light source. The results prove that alt-PSM with conventional partial coherence illumination can be applied in the manufacturing of random interconnect layer. This method can expand the process window effectively. The program that can achieve the pattern decomposition automatically is also developed. We’re sure that combined with optical proximity effect correction, this multi-exposure technology can fulfill the need of 0.1-μm generation logic IC lithography.

The Micro-processing & Nano-technology Laboratory at the Institute of Microelectronics, Chinese Academy of Sciences (CAS), is equipped with a GCA 3600F PG&3696, a JBX 6AII & JBX 5000LS EB, and an ETEC MEBES 4700S EB. For a long time we have been engaged in the research and manufacture on Optical Resolution Enhancement Technology (RET) and E-Beam Direct Writing Technology. In this paper the following technologies will be described: PSM, OPC EBDW,EPC,Match & Mixed Lithography technology. Through the application of RET in optical lithography system, we completed the 0.2 um pattern with the g line and I line light source, which is the necessary preparation for 100nm node with 193nm light source. By means of match & mixed lithography and nanofabrication technology, 20nm-50nm gate CMOS transistor and 100nm gate HEMT are successfully developed.

The living isospecific-cis-1,4-polymerization and block-copolymerization of (E)-1,3-pentadiene with 1,3-butadiene have been achieved for the first time by using cationic half-sandwich scandium catalysts.

As design rule continues to shrink, resolution enhancement techniques (RET) such as optical proximity correction (OPC) become more and more complex to enable design printability. As we know, typically integrated circuit (IC) layouts are simple shapes such as rectangles. However, high spatial frequency components of the mask spectrum that are not captured by the low-pass pupil result in a rounded image. In addition, the diffusion process in the postexposure bake (PEB) step makes the wafer rounding effects worse. This means that it is difficult to get the wafer image to match the design exactly at corners, even with the most aggressive OPC methodology. Therefore, pre-OPC site placement optimization is necessary to achieve high quality wafer images. In this work, a contour-based OPC methodology is proposed to minimize the time consumption in pre-OPC simulation site placement optimization and OPC job running. Rounded target contours that best describe the real intended wafer result are used as the target during OPC correction. By comparing classical OPC recipe-driven target point placement and contour-based OPC methodology, it is found that contour-based OPC methodology can achieve comparable image quality in a shorter turn around time (TAT) with fewer engineer resources.

Traditional double-exposure lithography (DEL) or double-patterning lithography (DPL) methodologies stem most from the resolution enhancement standpoint. A single mask with high feature densities is split into two exposure steps, each with lower feature densities that can be easily resolved. The DEL is proposed as the process window enhancement technology for sub-110-nm technology. Features with sparse pitches are printed by a first step of dense pitch exposures and a second exposure with dummy features removed. The pattern decomposition strategy described is similar to that of subresolution assisting features (SRAF). So it is compatible with the traditional rule-based SRAF implementation methodology. By comparing the depth of focus (DOF) of the 110-nm lithography process between the single exposure and the double exposure, it is found that the DOF for marginal features is extended by using double-exposure methodology, and thus extends the capability of KrF exposure tools. Furthermore, the link between the overlay performance and the overlap of the second exposure's trim slots over the first exposure is studied. The results show that the overlay control is within the KrF scanner capability. As a further study, the proposed double-exposure methodology for the 90-nm lithography process is evaluated.

Driven by steadily decreasing critical dimensions in the semiconductor technology, sub-resolution assisting feature (SRAF) has been proposed to enlarge the capability of the exposure technique to smaller pitch requirements exceeding the standard lithography specification by improving the through-focus process window. There are generally two types of SRAF implementation methodologies: the rule-based approach and the model-based approach. In this paper, the hybrid SRAF implementation methodology is proposed to benefit from these two methodologies. Firstly, the candidate rules are selected by using the process window aware optical proximity correction (OPC) model. Secondly, the candidate SRAF rules are taped out. Finally, the optimized candidates among the taped out SRAF rules are verified by wafer data. If the wafer data show that the SRAF rule will not meet the criteria, the SRAF implementation methodology will go back to evaluate other candidates. From the wafer data, it is proved that the hybrid SRAF implementation methodology can achieve an optimized through-focus process window in a short turn around time (TAT) with lower engineering and mask cost.