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Two rare-earth compounds [Ce(DNBA)3(DMSO)2]2 (1) and [La(DNBA)3(DMSO)2]2 (2) (where DNBA = 3,5-dinitrobenzoic acid, DMSO = dimethyl sulfoxide) have been synthesized and structurally charact...

The dearomatization of a series of electron-deficient nitrogen heterocycles has been achieved through a cobalt-catalyzed asymmetric cyclopropanation reaction. This reaction proceeds with high levels of enantio- and diastereoselectivity to afford unique cyclopropanes that can be further functionalized to provide complex heterocyclic building blocks.

Over the past two decades, the synchronization problem for dynamical networks has drawn significant attention due to its clear practical insight in biological systems, social networks, and neuroscience. In the case where a dynamical network cannot achieve the synchronization by itself, the feedback controller should be added to drive the network toward a desired orbit. On the other hand, the time delays may often occur in the nodes or the couplings of a dynamical network, and the existence of time delays may induce some undesirable dynamics or even instability. Moreover, in the course of implementing a feedback controller, the inevitable actuator limitations could downgrade the system performance and, in the worst case, destabilize the closed-loop dynamics. The main purpose of this paper is to consider the synchronization problem for a class of delayed dynamical networks with actuator saturations. Each node of the dynamical network is described by a nonlinear system with a time-varying delay and the intermittent control strategy is proposed. By using a combination of novel sector conditions, piecewise Lyapunov-like functionals and the switched system approach, delay-dependent sufficient conditions are first obtained under which the dynamical network is locally exponentially synchronized. Then, the explicit characterization of the controller gains is established by means of the feasibility of certain matrix inequalities. Furthermore, optimization problems are formulated in order to acquire a larger estimate of the set of initial conditions for the evolution of the error dynamics when designing the intermittent controller. Finally, two examples are given to show the benefits and effectiveness of the developed theoretical results.

Osteosarcoma is the most common type of primary malignancy of bone in children and adults. The treatment options for osteosarcoma are limited and are associated with a number of drawbacks. Therefore there is an urgent need to look for more efficient options for the treatment of this disease. Flavonoids have been considered as important anticancer agents due to their efficacy and lower cytotoxicity. In the present study we evaluated the anticancer effects of pelargonidin in U2OS osteosarcoma cell line.Cell viability was assessed by MTT assay. Reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and cell cycle analysis was done by flow cytometry. Expression of proteins was examined by western blotting.Pelargonidin exhibited significant anticancer effects on osteosarcoma U2OS cell line with an IC50 of 15 μM. The anticancer effects of pelargonidin were due to induction of autophagy as evidenced from the expression of LC3-I, LC-3II and Beclin-1. Moreover, pelargonidin triggered ROSinduced reduction in MMP and triggered G2/M cell cycle arrest. In addition, pelargonidin inhibited the expression of p-PI3K and p-AKT in a concentration-dependent manner.Taken together, these results indicated that pelargonidin may prove a potential lead drug for the treatment of osteosarcoma.

Catalytic conversion of CO2 including hydrogenation has attracted great attention as a method for chemical fixation of CO2 in combination with other techniques such as CO2 capture and storage. Potassium is a well-known promotor for many industrial catalytic processes such as in Fischer-Tropsch synthesis. In this work, we performed density functional theory (DFT) calculations to investigate the effect of potassium on the adsorption, activation, and dissociation of CO2 over Fe(100), Fe5C2(510) and Fe3O4(111) surfaces. The function of K was analyzed in terms of electronic interactions between co-adsorbed CO2 and K-surfaces which showed conspicuous promotion in the presence of K of the adsorption and activation of CO2. The adsorption strength of CO2 on these surfaces ranks as oct2-Fe3O4(111)Fe(100)Fe5C2(510). Generally, we observed a direct proportional correlation between the adsorption strength and the charges on the adsorbates. Adding K on the catalyst surface also reduces the kinetic barrier for CO2 dissociation. CO2 dissociation is more facile to occur on Fe(100) and Fe5C2(510) in the presence of K whereas the Fe3O4(111) surfaces impede CO2 dissociation regardless of the existence of K. Instead, a stable CO3- species is formed upon CO2 adsorption on Fe3O4(111) which will be directly hydrogenated when sufficient H* are available on the surface. Our results highlight the origin of the promotion effect of potassium and provide insight for the future design of K-promoted Fe-based catalysts for CO2 hydrogenation.

Using a genetic algorithm incorporated in density functional theory, we explore the ground state structures of fluoride anion-water clusters F

miR-34a is downregulated and a regulator of drug resistance in prostate cancer (PCa). However, the mechanism of miR-34a in chemoresistance of PCa remains largely unknown. In the present study, we first confirmed the hypermethylation‑induced downregulation of miR-34a in PCa tissues and cell lines, PC-3 and DU145. Additionally, transfection of miR-34a mimics and demethylation by 5-azacytidine both resulted in the upregulation of miR-34a expression, which further induced declined cell proliferation and the enhanced apoptosis in PCa cells. Upregulation of miR-34a enhanced the chemosensitivity of PC-3 and DU145 cells. Furthermore, overexpression of miR-34a reduced the expression of autophagy-related proteins, ATG4B, Beclin-1 and LC3B II/I in PCa cells and demethylation treatment showed similar effect. ATG4B was confirmed directly by miR-34a targeting in PCa. Finally, downregulated p-AMPK and upregulated p-mTOR were detected in miR-34a overexpressed PCa cells. Collectively, miR-34a enhances chemosensitivity by directly downregulating ATG4B-induced autophagy through AMPK/mTOR pathway in PCa.

This paper is concerned with the stabilization and l 2 gain control problems for a class of networked control systems with actuator saturation. By using the switched system model, the regional stabilization condition is firstly obtained. Then, the corresponding optimization problem is given to maximize the estimate of the domain of attraction. Under zero initial condition, the state feedback controller is also designed under which the l 2 gain from disturbances to the controlled output is less than a given positive scalar. As the further discussion, the improved stabilization condition is proposed by exploring a more relaxed inequality. Finally, a simulation example is given to illustrate the effectiveness and values of the obtained results in this paper.

3D printing technology is a great innovation in contemporary human society. It is the representative of the third industrial technology innovation of human technology revolution. It is a major technological innovation achievement by using multidisciplinary fusing innovation and multi field technology integration to gain. Based on the system views and the ecological system thought, it analyzes the 3D printing technology community composition which would be better understand the innovative mechanism and the innovative rules of 3D printing technology. A general framework of 3D printing technology community is given, and the structure of the material forming process (manufacturing process) and other related five aspects are analyzed.

Hordenine is an active compound found in several foods, herbs and beer. In this work, a novel sorbent was fabricated for selective solid-phase extraction (SPE) of hordenine in biological samples. The organic polymer sorbent was synthesized in one step in the plastic barrel of a syringe by a pre-polymerization solution consisting of methacrylic acid (MAA), 4-vinylphenylboronic acid (VB) and ethylene glycol dimethacrylate (EGDMA). The conditions for preparation were optimized to generate a poly(MAA-VB-EGMDA) monolith with good permeability. The monolith exhibited good enrichment efficiency towards hordenine. By using tyramine as the internal standard, a poly(MAA-VB-EGMDA)-based SPE-HPLC method was established for analysis of hordenine. Conditions for SPE, including volume of eluting solvent, pH of sample solution, sampling rate and sample volume, were optimized. The proposed SPE-HPLC method presented good linearity (R2 = 0.9992) within 10–2000 ng/mL and the detection limits was 3 ng/mL, which is significantly more sensitive than reported methods. The method was also applied in plasma and urine samples; good capability of removing matrices was observed, while hordenine in low content was well extracted and enriched. The recoveries were from 90.6 to 94.7% and from 89.3 to 91.5% for the spiked plasma and urine samples, respectively, with the relative standard deviations

Although the N-terminal region of Amyloid β (Aβ) peptides plays dual roles as metal-coordinating sites and conformational modulator, few studies have been performed to explore the effects of mutations at this region on the overall conformational ensemble of Aβ and the binding propensity of metal ions. In this work, we focus on how three familial Alzheimer's disease mutations (D7H, D7N, and H6R) alter the structural characteristics and thermodynamic stabilities of Aβ42 using molecular dynamics simulations. We observe that each mutation displays increased β-sheet structures in both N and C termini. In particular, both the N terminus and central hydrophobic region of D7H can form stable β-hairpin structures with its C terminus. The conserved turn structure at Val²⁴-Lys²⁸ in all peptides and Zn²⁺-bound Aβ42 is confirmed as the common structural motif to nucleate folding of Aβ. Each mutant can significantly increase the solvation free energy and thus enhance the aggregation of Aβ monomers. The correlation dynamics between Aβ(1-16) and Aβ(17-42) fragments are elucidated by linking the domain motions with the corresponding structured conformations. We characterize the different populations of correlated domain motions for each mutant from a more macroscopic perspective, and unexpectedly find that Zn²⁺-bound Aβ42 ensemble shares the same populations as Aβ42, indicating that the binding of Zn²⁺ to Aβ follows the conformational selection mechanism, and thus is independent of domain motions, even though the structures of Aβ have been modified at a residue level.

Iridium-catalyzed asymmetric hydrogenation of N-alkyl-2-alkylpyridinium salts provided 2-aryl-substituted piperidines with high levels of enantioselectivity. Simple benzyl and other alkyl groups successfully activated the challenging pyridine substrates toward hydrogenation. The use of the unusual chiral-phosphole-based MP(2) -SEGPHOS was the key to the success of this approach which provides a versatile and practical procedure for the synthesis of chiral piperidines.

This paper investigates the global asymptotic stability problem for recurrent neural networks with multiple time-varying delays. Using the free-weighting matrix technique, and incorporating the interconnected information between the upper bounds of multiple time-varying delays, two less conservative delay-dependent asymptotic stability conditions are proposed, which are expressed by linear matrix inequalities, and can be conveniently solved by the existing softwares. Numerical examples show the reduce conservatism of the obtained conditions.

To investigate the distribution of statin therapy correlated gene polymorphism allele CYP2D6*10 (C188T) in Ningxia Hui nationality and to discuss the relationship between the gene polymorphism allele CYP2D6*10 (C188T) and the lipid-lowering efficacy of simvastatin and hyperlipidemia.One hundred and fifty healthy people (80 males and 70 females) and 200 hyperlipidemia patients (105 males and 95 females) were recruited at Ningxia People's Hospital. Genotypes were determined by using allele-specific amplification (ASA-PCR) in 150 healthy controls and 200 patients with hyperlipidemia. Relationships between genotypes and lipid levels and the lipid-lowering efficacy of simvastatin were analyzed.The distribution frequency of the CYP2D6*10 allele was 47.6% in the Ningxia Hui nationality. There was no significant correlation between the CYP2D6*10 allele and hyperlipidemia. At 8 weeks after treatment with simvastatin, total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels were more obviously decreased with the CC genotype than the CT and TT genotypes, with significant differences.Distribution of the gene polymorphism of CYP2D6*10 is ethnically and geographical different. The allele T of CYP2D6*10 is not related to hyperlipidemia. CC expression seemed to increase the lipid-lowering effects of simvastatin. The hyperlipidemia patients with CC genotype should take lower doses of simvastatin than those with CT/TT genotype in the Ningxia Hui population.

In this paper, the robust stabilization and l 2 gain control are investigated for a class of uncertain discrete-time piecewise-affine systems with input saturation and state constraints. By introducing some auxiliary feedback matrices, the LMI-based local stabilization condition is firstly proposed, where the designed controller can be saturated, and meanwhile, the domain of attraction is well estimated. Under energy bounded disturbance, the disturbance tolerance condition is proposed under which all trajectories starting from the origin will remain inside a bounded state region, then the l 2-gain controller is designed in the restricted region. Finally, numerical examples and simulations illustrate the effectiveness and the reduced conservativeness of the proposed results.

General methods for the highly site-selective Suzuki monocoupling of 3,5-dichloropyridazines have been discovered. By changing the ligand employed, the preferred coupling site can be switched from the 3-position to the 5-position, typically considered the less reactive C-X bond. These conditions are applicable to the coupling of a wide variety of aryl-, heteroaryl-, and vinylboronic acids with high selectivities, thus enabling the rapid construction of diverse arrays of diarylpyradazines in a modular fashion.

This paper reports the design, calibration and application of multiplexed arrays of piezoresistive field-effect transistor stress sensors fabricated in a standard complementary-metal-oxide semiconductor (CMOS) process. Two complementary arrays of 256-current mirror sensor cells provide high spatial density stress mapping with approximately 300 pts/mm2 using only a 1.5 μm process. The arrays are sequentially scanned by an on-chip counter, producing efficient stress measurement, and the sensors resolve normal and shear stresses on the surface of the die with resolution below 1 MPa. The CMOS sensor chips have been used to map stress over a large portion of the die in chip-on-beam and encapsulated chip-on-beam samples, as well as a ceramic dual-in-line package with its cavity filled with underfill material. Finite-element simulation results correlate well with the measured stress distributions. The experimental results from these chips are used to validate finite-element simulation models, and the array designs can be used as subarrays in much larger test chips.

Qian-Yu decoction (QYD) is a traditional Chinese medicinal recipe composed of Radix astragali (Astragalus membranaceus (Fisch.) Bunge var. mongholicus (Bunge) P.K. Hsiao, Fabaceae ), Herba epimedii (Epimedium brevicornum Maxim., Berberidaceae), Herba leonuri (Leonurus japonicus Houtt., Lamiaceae), Cortex phellodendri (Phellodendron chinense Schneid., Rutaceae) and Radix achyranthis bidentatae (Achyranthes bidentata Bl., Amaranthaceae). This study aimed to evaluate the therapeutic activity of QYD against carrageenan-induced chronic prostatic/chronic pelvic pain syndrome (CP/CPPS) in rats and further elucidate its effective components. Three types of components, total polysaccharides, total flavonoids and total saponins were separately extracted from QYD. Carrageenan-induced CP/CPPS rats were intragastrically administered with lyophilized product of QYD, individual extracts and all the combined forms of extracts for three weeks. Prostatic index (PI) was determined and histopathological analysis was performed. The levels of tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β), cyclooxygenase-2 (COX-2) and prostaglandin E2 (PEG2) in rat prostate tissues were measured using ELISA. The production of inducible nitric oxide synthase (iNOS) was evaluated by an enzymatic activity assay, and the release of nitric oxide (NO) was determined by a nitrate/nitrite assay. Treatment with QYD significantly ameliorated the histological changes of CP/CPPS rats and reduced the PI by 44.3%, with a marked downregulation of TNF-α (42.8% reduction), IL-1β (45.3%), COX-2 (36.6%), PGE2 (44.2%), iNOS (54.1%) and NO (46.0%). Each of three extracts attenuated the symptom of CP/CPPS, but much more weakly than QYD. The combined administration of three extracts showed efficacy comparable to that of QYD while better than that of any combination of two extracts. A principal component analysis of the six inflammatory mediators as variables indicated that the effects of TS on CP/CPPS were rather different from those of TF and TP, which were similar. QYD can be beneficial in prevention and treatment of CP/CPPS. Polysaccharides, flavonoids and saponins, as the major effective components of QYD, exert a cooperative effect on CP/CPPS.

Various fused nitrogen containing heteroarenes, including electron-deficient ones, are cyclopropanated in a highly diastereoselective and enantioselective manner.

Tributyltin (TBT), a highly toxic environmental contaminant, has been shown to induce caspase-3-dependent apoptosis in human amniotic cells through protein phosphatase 2A (PP2A) inhibition and consequent JNK activation. This in vivo study was undertaken to further verify the results derived from our previous in vitro study. Mice were orally dosed with 0, 10, 20, and 60 mg/kg of body weight TBT, and levels of PP2A, reactive oxygen species (ROS), mitogen-activated protein kinase (MAPK), Bax/Bcl-2, and caspase-3 were detected in the mouse livers. Apoptosis was also evaluated using the TUNEL assay. The results showed that PP2A activity was inhibited, ROS levels were elevated, and MAPKs including ERK, JNK, and p38 were activated in mouse livers treated with the highest dose of TBT. Additionally, the ratio of Bax/Bcl-2 was increased, caspase-3 was activated, and apoptosis in mouse livers could be detected in the highest dose group. Therefore, a possible signaling pathway in TBT-induced apoptosis in mouse livers involves PP2A inhibition and ROS elevation serving a pivotal function as upstream activators of MAPKs; activation of MAPKs in turn leads to an increase in the Bax/Bcl-2 ratio, ultimately leading to the activation of caspase-3. The results give a comprehensive and novel description of the mechanism of TBT-induced toxicity. © 2011 Wiley Periodicals, Inc. Environ Toxicol 29: 234–242, 2014.

This paper considers the stabilization problem of impulsive switched linear systems with saturated control input, in which the impulses are viewed as control or disturbances. Under arbitrary switching rule and dwell time switching rule, the local stabilization conditions are obtained in terms of LMIs, respectively. The corresponding optimization problems are formulated to obtain a bigger attractive region. Our results show that impulsive control can recover part of attractive region, or allow a wide range of switching signals. If the impulses occur as disturbances, we have to increase the dwell time of switching signals to offset the effects of disturbances. Numerical examples are given to show the effectiveness of the results proposed.

A novel composite heterojunction photocatalysts Sr(Zr 1−x Y x )O 3 /TiO 2 /CdS was prepared by sol-gel combustion method. Its photoatalytic properties under visible light were investigated through degradation of methyl orange. XRD, SEM, Uv-Vis and PL techniques were used to characterize the structure and optical properties of the sample. The results showed that the photocatalytic activity of prepared composite photocatalysts under visible light is 2.85 times of that of pure TiO 2 .

The Continuously Variable Temperature Phosphorous Gettering process using a Porous Silicon Layer (PSL-CVTPG) was proposed. PSL-CVTPG process can getter unwanted impurities from Solar-Grade silicon (SOG-Si) wafers and upgrade photovoltaic properties of solar cells more efficiently than conventional Constant Temperature Phosphorus Gettering process using a Porous Silicon Layer (PSL-CTPG). The resistivity, and mobility of majority carriers, and the effective lifetime of minority carriers were evaluated; the results showed that under certain conditions, the gettering effect of the PSL-CVTPG is better than that of the optimum PSL-CTPG. By orthogonal experiments, the optimum PSL-CVTPG conditions were found to be 900 °C/60 min+750 °C/60 min. PSL-CVTPG and CTPG processes under their respective optimum gettering conditions were used in the fabrication of solar cells, and cells based on SOG-Si wafers purified by the PSL-CVTPG process exhibited an amelioration in photovoltaic performances.

A HPLC-DAD method was used and validated for the simultaneous determination of five flavonoids (rutin, quercitrin, quercetin, kaempferol, and isorahamnetin) in rat plasma. Chromatographic separation was performed using a Kromasil C18 column (250 × 4.6 mm, 5 µm) maintained at 35°C. The mobile phase was a mixture of methanol and 0.1% formic acid with a step linear gradient. At 1.0 mL/min flow rate, the eluent of five flavonoids were detected simultaneously at 350 nm with good separation. Under optimum conditions, good linear relationship between the peak area and the concentrations were obtained in the ranges of 0.2525 ∼ 20.2, 0.1208 ∼ 9.66, 0.1008 ∼ 20.16, 0.031 ∼ 2.46, and 0.098 ∼ 7.84 µg/mL for rutin, quercitrin, quercetin, kaempferol, and isorhamnetin, respectively. The correlation coefficient for each analyte was above 0.999. The intra-day and inter-day precisions were better than 7% and 10%. The detection limit (S/N = 3) for rutin, quercitrin, quercetin, kaempferol, and isorhamnetin were 0.01...

In order to enlarge the utilization ratio of the visible light, nanometer TiO2 photocatalysts doped with Er3+:Y3Al5O12 (Er3+:YAG) upconversion luminescence agent were synthesized. The as-synthesized samples were characterized by X-ray diffraction, transmission electron microscopy, and ultraviolet−visible absorption spectra. The visible light photocatalytic activities of the samples were studied by photodegradation of methylene blue while considering the influences of the dopant concentration, calcination temperature, initial concentration of methylene blue, and catalyst amount. The results showed that the degradation rate in the presence of the doped sample was 2 times that of the undoped one. The photocatalytic mechanics of the degradation reaction was investigated. The results showed that primarily the oxidation mechanics of the photoproduction holes occurred, and the methylene blue was degraded thoroughly in the presence of the doped samples. All the results proved that the doped TiO2 had more excellen...

The DEM generalization is the basis of multi-dimensional observation, the basis of expressing and analyzing the terrain. DEM is also the core of building the Multi-Scale Geographic Database. Thus, many researchers have studied both the theory and the method of DEM generalization. This paper proposed a new method of generalizing terrain, which extracts feature points based on the tree model construction which considering the nested relationship of watershed characteristics. The paper used the 5 m resolution DEM of the Jiuyuan gully watersheds in the Loess Plateau as the original data and extracted the feature points in every single watershed to reconstruct the DEM. The paper has achieved generalization from 1:10000 DEM to 1:50000 DEM by computing the best threshold. The best threshold is 0.06. In the last part of the paper, the height accuracy of the generalized DEM is analyzed by comparing it with some other classic methods, such as aggregation, resample, and VIP based on the original 1:50000 DEM. The outcome shows that the method performed well. The method can choose the best threshold according to the target generalization scale to decide the density of the feature points in the watershed. Meanwhile, this method can reserve the skeleton of the terrain, which can meet the needs of different levels of generalization. Additionally, through overlapped contour contrast, elevation statistical parameters and slope and aspect analysis, we found out that the W8D algorithm performed well and effectively in terrain representation.

Although having advantages of high integration, Low power consumption and strong processing capability, etc., it is not easy for SDRAM to be developed and applied because of its timing complexity. To reduce costs, and shorten the development period, combining with features of strong reconfiguration and portability for the design based on FPGA, particular timing constraints for the read and write processes of SDRAM controller were made and SDRAM controller IP soft core was designed according to SDRAM control norms, using EDA top-down design method. The IP core was verified with Altera's FPGA- EP2C35F484C8 devices. Timing simulation and SignalTapII logic analyzer sampling results show that the designed IP core is in line with SDRAM timing requirements and can operate reliably and continuously. The design has high reliability and universal applicability.

Nonfibrillar neurotoxic amyloid β (Aβ) oligomer structures are typically rich in β-sheets, which could be promoted by metal ions like Zn(2+). Here, using molecular dynamics (MD) simulations, we systematically examined combinations of Aβ40 peptide conformations and Zn(2+) binding modes to probe the effects of secondary structure on Aβ dimerization energies and kinetics. We found that random conformations do not contribute to dimerization either thermodynamically or kinetically. Zn(2+) couples with preformed secondary structures (α-helix and β-hairpin) to speed dimerization and stabilize the resulting dimer. Partial α-helices increase the dimerization speed, and dimers with α-helix rich conformations have the lowest energy. When Zn(2+) coordinates with residues D1, H6, H13, and H14, Aβ40 β-hairpin monomers have the fastest dimerization speed. Dimers with experimentally observed zinc coordination (E11, H6, H13, and H14) form with slower rate but have lower energy. Zn(2+) cannot stabilize fibril-like β-arch dimers. However, Zn(2+)-bound β-arch tetramers have the lowest energy. Collectively, zinc-stabilized β-hairpin oligomers could be important in the nucleation-polymerization of cross-β structures. Our results are consistent with experimental findings that α-helix to β-structural transition should accompany Aβ aggregation in the presence of zinc ions and that Zn(2+) stabilizes nonfibrillar Aβ oligomers and, thus, inhibits formation of less toxic Aβ fibrils.

A semi-regulated dual-output (SR-DO) LLC resonant converter is proposed for high step-down multiple output conversion with wide input voltage range. The proposed SR-DO LLC converter is used as the front-end converter for a two-stage multiple-output converter. The SR-DO LLC operates as a DC-DC converter with regulated outputs when the input voltage is low and as a DC-DC transformer with unregulated outputs when the input voltage is high to provide optimized intermediate DC-bus voltages for the second-stage point-of-load converters. A hybrid center-tapped and full-bridge rectifier is proposed for the SR-DO LLC converter. The switches and associated drivers are reduced with the proposed hybrid rectifier and hence high efficiency and high power density can be achieved. Experimental results are given to verify the effectiveness of the proposed solutions.

Chiral piperidines are easily prepared by Ir-catalyzed asymmetric hydrogenation of alkylpyridinium salts.

The essay probes into the present problems of the measurement errors caused by harmonic interference in the electric monitoring equipment for underground coal mine. We applied three-phase watt-hour meter in view of FFT(Fast Fourier Transformation) algorithm based on Industrial Ethernet, which can effectively analyze the harmonic component of the voltage and the current from the field. This can accurately calculate the electrical parameters of electrical equipment, improving the quality of electricity and achieving optimal energy management of coal mine.

Two Mn(III)Re(I) binuclear complexes were prepared as catalyst-photosensitizer models, in which the chiral pyrrolidine salen Mn(III) unit was covalently bonded to an Re(I) bipyridyl carbonyl moiety via a carboxamide linkage. The spectral and electrochemical properties of the Mn(III)Re(I) complexes were studied. ∗Corresponding authors. Tel.: +86-411-88993886. Fax: +86-411-83702185. Email: symbueno@vip.sina.com

A series of chiral (pyrrolidine salen)Mn(III) complexes were synthesized front N-aza-substituted (R,R)-N,N'-bis(3,5-di-tert-butylsalicylidene)-3.4-diaminopyrrolidine salen ligands. High yields and ...

A catalyst-photosensitizer binuclear Mn(III)Ru(II) complex was prepared, in which the catalyst moiety of the Mn(III) unit with a chiral pyrrolidine salen ligand was covalently linked to a photosensitizer of the Ru(II) tris(bipyridyl) fragment. The electrochemical and photophysical properties of the Mn(III)Ru(II) complex were studied.

Insights into the role played by modified cinchona alkaloids in the Sharpless asymmetric dihydroxylation inspired studies of modified cinchona alkaloids as chiral organic catalysts that lead to the development of highly enantioselective alcoholyses for the desymmetrization, kinetic resolution, and dynamic kinetic resolution of cyclic anhydrides, cyanation of ketones, and 1,4-addition of thiols to cylic enones. These studies demonstrate the potential of modified cinchona alkaloids as broadly useful chiral organic catalysts for asymmetric synthesis.

A great need exists for comprehensive biomass-pyrolysis models that could predict yields and evolution patterns of selected volatile products as a function of feedstock characteristics and process conditions. Low heating rate data obtained from a thermogravimetric analyzer (TGA), coupled with Fourier transform infrared analysis of evolving products (TG-FTIR), were used to perform kinetic analysis of tobacco pyrolysis. The results were utilized to create input to a biomass-pyrolysis model based on first-order kinetic expressions with a Gaussian distribution of activation energies. Pyrolysis simulations were carried out for high heating rate conditions, and predicted product yields were compared with literature data.

An efficient protocol for the palladium-catalyzed Suzuki–Miyaura cross-coupling reaction of unprotected haloimidazoles is reported. The relatively mild reaction conditions allow for ready access to a wide array of functionalized imidazole derivatives in good to excellent yields. The synthetic utility of this method is demonstrated by the total synthesis of nortopsentin D.

The identification of a secondary nucleation pathway in the early aggregation of amyloid peptides suggests that the generation of toxic oligomers involves both monomers and preformed fibril seeds. To elucidate the underlying molecular mechanism, a set of one-pot coarse-grained molecular dynamics simulations was performed to investigate the self-assembly of amyloid β peptides in the presence of fibril seeds. It was observed that fibril seeds alone randomly assemble into an elongated protofibril, whereas monomers alone form an elongated globular oligomer with various morphologies. In the mixture of monomers and fibril seeds, both the self-assembly of monomers into small oligomers and the association of monomers and oligomers on the surface of fibril seeds are primarily driven by hydrophobic interactions. The cooperativity of conformational selection and competition leads to different binding propensity of two hydrophobic surfaces of fibril seeds. The molecular architecture of the final aggregate shows that the fibril seeds establish the elongated framework, and oligomers cover them. Oligomers exposed to the solvent are less compact and unstable and can be disassociated from the fibril seeds, providing an origin for oligomers generated from the secondary nucleation pathway.

Hordenine is an active compound found in several foods, herbs and beer. In this work, a novel sorbent was fabricated for selective solid-phase extraction (SPE) of hordenine in biological samples. The organic polymer sorbent was synthesized in one step in the plastic barrel of a syringe by a pre-polymerization solution consisting of methacrylic acid (MAA), 4-vinylphenylboronic acid (VB) and ethylene glycol dimethacrylate (EGDMA). The conditions for preparation were optimized to generate a poly(MAA-VB-EGMDA) monolith with good permeability. The monolith exhibited good enrichment efficiency towards hordenine. By using tyramine as the internal standard, a poly(MAA-VB-EGMDA)-based SPE-HPLC method was established for analysis of hordenine. Conditions for SPE, including volume of eluting solvent, pH of sample solution, sampling rate and sample volume, were optimized. The proposed SPE-HPLC method presented good linearity (R(2) = 0.9992) within 10-2000 ng/mL and the detection limits was 3 ng/mL, which is significantly more sensitive than reported methods. The method was also applied in plasma and urine samples; good capability of removing matrices was observed, while hordenine in low content was well extracted and enriched. The recoveries were from 90.6 to 94.7% and from 89.3 to 91.5% for the spiked plasma and urine samples, respectively, with the relative standard deviations4.7%.

Although the N-terminal region of Amyloid β (Aβ) peptides plays dual roles as metal-coordinating sites and conformational modulator, few studies have been performed to explore the effects of mutations at this region on the overall conformational ensemble of Aβ and the binding propensity of metal ions. In this work, we focus on how three familial Alzheimer's disease mutations (D7H, D7N, and H6R) alter the structural characteristics and thermodynamic stabilities of Aβ42 using molecular dynamics simulations. We observe that each mutation displays increased β-sheet structures in both N and C termini. In particular, both the N terminus and central hydrophobic region of D7H can form stable β-hairpin structures with its C terminus. The conserved turn structure at Val²⁴-Lys²⁸ in all peptides and Zn²⁺-bound Aβ42 is confirmed as the common structural motif to nucleate folding of Aβ. Each mutant can significantly increase the solvation free energy and thus enhance the aggregation of Aβ monomers. The correlation dynamics between Aβ(1-16) and Aβ(17-42) fragments are elucidated by linking the domain motions with the corresponding structured conformations. We characterize the different populations of correlated domain motions for each mutant from a more macroscopic perspective, and unexpectedly find that Zn²⁺-bound Aβ42 ensemble shares the same populations as Aβ42, indicating that the binding of Zn²⁺ to Aβ follows the conformational selection mechanism, and thus is independent of domain motions, even though the structures of Aβ have been modified at a residue level.

A concise, enantioselective synthesis of the HCV NS5a inhibitor MK-8742 (1) is reported. The features of the synthesis include a highly enantioselective transfer hydrogenation of an NH imine and a dynamic diastereoselective transformation. The synthesis of this complex target requires simple starting materials and nine linear steps for completion.

The first enantioselective synthesis of (+)-chrysanthemol 1 was carried out starting from (+)-dihydrocarvone in ten steps. In our studies, a facile synthetic strategy has been developed for introduction of C3-C4 double bond into a eudesmane skeleton.