汽轮机起到过程温升分配对转子热应力的影响研究

在汽轮降低转子的启动和停止过程中;对热应力的控制要求较高;尤其是对控制转子因温升产生的疲劳、裂纹发生和扩展等具有很大的影响。本文中根据汽轮机起到过程温升分配对转子热应力场计算模型的建立展开研究;并对结果进行分析。

A Multifunctional Chiral Metasurface with Asymmetric Transmission and Linear-Polarization Conversion

In this paper,a multifunctional chiral metasurface is presented to achieve asymmetric transmission(AT)and linear-polarization conversion(LPC).The designed metasurface consists of a cross swords-like shape and two holes in the lower side of the unit cell.In the frequency band from 8.3 GHz to 10.4 GHz,AT is realized with more than 90%efficiency and the same chiral metasurface transforms linear polarized wave into its orthogonal counterpart with high efficiency.For LPC,the polarization conversion ratio(PCR)is greater than 95%.The proposed metasurface is stable against the incident angles of striking electromagnetic(EM)waves up to 60°for both operations of AT and LPC.

Teleportation of an Arbitrary Three-Particle State via Three EPR Pairs

A scheme of teleportation of an arbitrary three-particle state is presented when three pairs of entangled particles are used as quantum channels. After the Bell state measurements are operated by the sender, the original state with deterministic probability can be reconstructed by the receiver when a corresponding unitary transformation is followed.

Conjugate addition‐enantioselective protonation to forge tertiary stereocentresαto azaarenes via cooperative hydrogen atom transfer and chiral hydrogen‐bonding catalysis

Cooperative hydrogen atom transfer and chiral hydrogen‐bonding catalysis as a new platform for the asymmetric synthesis of azaarene derivatives is reported.By using a tetrabutylammonium decatungstate as the photocatalyst and a chiral phosphoric acid as the hydrogen‐bonding catalyst,transformations of a variety of commercially available hydrocarbons and silanes with diverseα‐branched 2‐vinylazaarenes could efficiently experience a tandem radical conjugate addition and enantioselective protonation process,providing a convenient and fully atom economical approach to access a range of valuable enantioenrichedα‐tertiary azaarenes in high yields with good to excellent enantioselectivities(up to 93%ee).Through the direct use of tert‐butyl methylcarbamate as the feedstock,this method enables a highly practical and concise synthesis of the enantiomerically pure medicinal molecule pheniramine(Avil).

Prediction of mass transfer coefficients in an asymmetric rotating disk contactor using effective diffusivity

Mass transfer characteristics have been investigated in a 113 mm diameter asymmetric rotating disk contactor of the pilot plant scale for two different liquid–liquid systems. The effects of operating parameters including rotor speed and continuous and dispersed phase velocities on the volumetric overall mass transfer coefficients are investigated. The results show that the mass transfer performance is strongly dependent on agitation rate and interfacial tension, but only slightly dependent on phase flow rates. In this study, effective diffusivity is used instead of molecular diffusivity in the Grober equation for estimation of dispersed phase overall mass transfer coefficient.The enhancement factor is determined experimentally and there from an empirical expression is derived for prediction of the enhancement factor as a function of Reynolds number. The predicted results compared to the experimental data show that the proposed correlation can efficiently predict the overall mass transfer coefficients in asymmetric rotating disk contactors.

Relative Molecular Orientations in Organic Optoelectronic Films Probed via Polarization-Selected UV/IR Mixed Frequency Ultrafast Spectroscopy

Molecular packing patterns are crucial factors determining electron/energy transfer processes that are critical for the optoelectronic properties of organic thin film devices.Herein,the polarization-selective ultraviolet/infrared(UV/IR)mixed frequency ultrafast spectroscopy is applied to investigate the relative molecular orientations in two organic thin films of 7-(diethylamino)coumarin-3-carboxylic acid(DEAC)and perylene.The signal anisotropy changes caused by intermolecular energy/electron transfers are utilized to calculate the cross angles between the electronic transition dipole moment of the donor and the vibrational transition dipole moments of the acceptor,yielding the relative orientation between two adjacent molecules.Using this method,the relative orientation angle in DEAC film is determined to be 53.4°,close to 60°of its single crystalline structure,and that of the perylene film is determined to be 6.2°,also close to-0.2°of its single crystalline structure.Besides experimental uncertainties,the small difference between the angles determined by this method and those of single crystals also results from the fact that the thin film samples are polycrystalline where some of the molecules are amorphous.

Current Reversal and Negative Conductance for a Super-Conducting Junctions Device

In the paper, we study a super-conducting junctions device subject to an input periodic signal and a constant force. It is shown that, for this device, we can get current reversals for the current of the electron pairs versus the frequency of the periodic signal and negative conductance for the current of the electron pairs as a function of the constant force.

Relativistic Treatment of Spinless Particles Subject to a Rotating Deng-Fan Oscillator

The bound state solutions of the Klein-Gordon equation with the rotating Deng-Fan molecular potential are presented by using a proper approximation to the centrifugal term within the framework of equal scalar and vector Deng-Fan potentials. It is shown that the solutions can be expressed by the generalized hypergeometric functions. The normalized wavefunctions are also derived.

Low-Energy Kπ Phase Shifts in Chiral SU（3） Quark Model

The low-energy region kaon-pion S- and P-wave phase shifts with isospin I = 1/2 and I = 3/2 are dynamically studied in the chiral SU(3) quark model by solving a resonating group method equation. The model parameters are taken to be the values fitted by the energies of the baryon ground states and the kaon-nucleon elastic scattering phase shifts of different partial waves. As a preliminary study the s-channel q(-q) annihilation interactions are not included since they only act in the very short range and are subsequently assumed to be unimportant in the low-energy domain. The numerical results are in qualitative agreement with the experimental data.

The effect of transition metal ions (M^(2+)=Mn^(2+),Ni^(2+),Co^(2+),Cu^(2+)) on the chemical synthesis polyaniline as counter electrodes in dye-sensitized solar cells

The effect of transition metal ions(M^(2+)=Mn^(2+),Ni^(2+),Co^(2+),Cu^(2+)) on the chemical synthesis of polyaniline(PANI) used as a platinum-free counter electrode(CE) in dye-sensitized solar cells(DSSCs) was investigated.PANI was synthesized by co-polymerization of aniline in the presence of different transition metal ions by using potassium dichromate in acidic medium. It was found that the ion doping of PANI showed a certain catalytic activity for the regeneration of traditional iodide/triiodide(I^-/I_3^-) redox couples. The power conversion efficiency(η) of PANI CEs doped with Mn^(2+),Ni^(2+),Co^(2+) (4.41%, 2.36% and 2.10%, respectively) were higher than 1.94%, the value measured for PANI CE without doping. Doping with Cu^(2+)decreased the power conversion efficiency of PANI CE(PANI-Cu^(2+) η = 1.41%). The electrical properties of the PANI, PANI-Ni^(2+), PANI-Co^(2+),PANI-Mn^(2+) and PANI-Cu^(2+) were studied by cyclic voltammetry(CV), impedance(EIS), and Tafel polarization curve. The experimental results confirmed that PANI was affected by the doping of different transition metal ions(M^(2+)=Mn^(2+),Ni^(2+),Co^(2+),Cu^(2+)). These results indicate a potential application of ion doped PANI as counter electrode in cost-effective DSSCs.

Upregulation of Nrf2-regulated gene expression by tBHQ alleviates cyclophosphamide-induced hematotoxicity in mice

Hematological toxicity （bone marrow suppression） is the most common dose-limiting adverse effect of chemotherapies. The nuclear factor erythroid 2-related factor 2 （Nrf2） is a pivotal coordinator of cellular defensive responses against chemical insults in many tissues including bone marrow. In the present study, the effects of tert-butylhydroquinone （tBHQ） on the expression of Nrf2-regulated genes in peripheral blood cells and cyclophosphamide （CTX）-induced hematotoxicity in mice were investigated. CTX induced apoptosis of peripheral blood nucleated cells and leukopenia in mice, accompanied by mobilization of bone marrow hematopoietic cells, tBHQ treatment induced the expression of Nrf2-regulated genes such as heine oxygenase 1 （HO1） and glutamate-cysteine ligase catalytic subtmit （GCLC） in RAW264.7 mouse macrophage cells and peripheral blood cells both in vitro and in vivo. Interestingly, pretreatment with tBHQ alleviated CTX-induced mouse peripheral blood cell apoptosis and leukopenia in vivo, indicating possible involvement of Nrf2 in the protection against CTX-induced hematotoxicity. This study provides new information on the chemotherapy-induced hematotoxicity, and suggests Nrf2 could serve as a target for the development of chemoprotectants against hematotoxicity.

Performance Test and Flow Measurement of Contra-Rotating Axial Flow Pump

An application of contra-rotating rotors has been proposed against a demand for developing higher specific speed axial flow pump. In the present paper, the advantage and disadvantage of using contra-rotating rotors are described in comparison with conventional type of rotor-stator, based on theoretical and experimental investigations. The advantages are as follows： （1） The pump is inherently designed as smaller sized and at lower rotational speed. （2） A stable head-characteristic curve for flow rate with negative slope appears. （3） As the rear rotor rotational speed is varied as independent control of front rotor, the wider range of high performance operation is obtained by rear rotor speed control in addition to front rotor speed control. The disadvantages are as follows： （1） The structure of double shaft system becomes complex. （2） The pump performance is inferior at over flow rate as the rear rotor loading is weakened. （3） The blade rows interaction from rear rotor to front rotor more strongly appears. Then the rear rotor design is a key to achieve higher pump performance. Some methods to overcome these disadvantages will be discussed in more details toward wider usage of contra-rotating axial flow pump in various industrial fields.

Docking and field-based QSAR studies of S-DABOs as HIV-1 reverse transcriptase inhibitors

HIV-1 reverse transcriptase（RT） inhibitors are major components of HAART（highly active antiviral therapy）. The S-DABOs（dihydro-alkylthio-benzyl-oxopyrimidines） series and their similar skeletons have exhibited preferable activities to inhibit HIV-1 RT. In the present study, we generated field-based QSAR models using common structure alignment, which was characterized by Gaussian steric, electrostatic, hydrophobic, hydrogen bond donor, hydrogen bond acceptor and aromatic ring fields（R2 = 0.8421, RCV2 = 0.5949 for the training set, Q2 = 0.5486, Pearson-r = 0.7460 for the test set）. Docking, pocket surface and contour map analyses were carried out. Key pharmacophore features were investigated, including（i） π-π interaction with residue Tyr181, Tyr188 and Trp229, σ-π interaction with His236,（ii） hydrogen bond with residue Lys101 and halogen bond with residue Tyr188. The docking analysis and field-based QSAR models could provide reasonable guidance in the rational design of potent HIV-1 RT inhibitors.

Selection rules of electromagnetic transitions for chirality-parity violation in atomic nuclei

The nuclear Chirality-Parity(ChP) violation, a simultaneous breaking of chiral and reflection symmetries in the intrinsic frame, is investigated with a reflection-asymmetric triaxial particle rotor model. A new symmetry for an ideal ChP violation system is found and the corresponding selection rules of the electromagnetic transitions are derived. The fingerprints for the ChP violation including the nearly degenerate quartet bands and the selection rules of the electromagnetic transitions are provided. These fingerprints are examined for ChP quartet bands by taking a two-j shell h11/2 and d5/2 with typical energy spacing for A = 130 nuclei.

Similar pyridinone compounds with different activities of anti-HIV-1 reverse transcriptase

Among the structurally diverse NNRTIs, pyridinone scaffolds demonstrate high potency against HIV-1 wild type and drug-resistant strains. During the optimization of our pyridinone compound 1（LAM-trans）, we found that the introduction of the N atoms in the C-4 position could dramatically improve the water solubility（7b）, whereas protonation of the piperidine N atom resulted in a decrease in its hydrophobic interaction with the binding pocket. In particular, protonation altered the orientation of the alicyclic rings in the hydrophobic pocket, thus impeding the formation of key halogen bond and eventually leading to a huge change in anti-HIV-1 RT activity. These results provided theoretical and experimental basis for the subsequent structural modification of pyridinone compounds.

Mn-doped ZnS quantum dots/methyl violet nanohybrids for room temperature phosphorescence sensing of DNA

Mn-doped ZnS quantum dots/methyl violet nanohybrids were explored to develop a novel room temperature phosphorescence (RTP) sensor for the detection of DNA. Methyl violet (MV) as the electron acceptors was adsorbed on the surface of the quantum dots (QDs) to quench the RTP of the Mn-doped ZnS QDs through an electron-transfer process under excitation. The addition of DNA recovered the RTP signal of the Mn-doped ZnS QDs due to the binding of MV with DNA and the removal of MV from the surface of the Mn-doped ZnS QDs. Under the optimal conditions, the enhanced RTP intensity of the Mn-doped ZnS QDs/MV nanohybrids linearly increased with the concentration of DNA from 0.08 to 12 mg L-1 with the detection limit of 33.6 μg L-1. The relative standard deviation for eleven replicate detections of the reagent blank was 3.7%. The developed method was applied to the detection of DNA in spiked urine samples with recoveries of 96%-103% without interference from nonspecific fluorescence.

Experimental and numerical investigations on convective heat transfer of dual piezoelectric fans

An investigation is performed to study the convective heat transfer performance under dual piezoelectric fans. Three main aspects are involved in the current study. Firstly, vibration tests for dual specific piezoelectric fans actuating at the first-mode resonant frequency are conducted to illustrate the influence roles of vibrating phase difference and fan-to-fan pitch on the piezoelectric fan vibration amplitude. Secondly, heat transfer measurements are made to compare the heat transfer among single fan, dual fans in-phase and dual fans out-of-phase. Thirdly, three-dimensional numerical simulations are conducted to reveal the influence mechanism of dual piezoelectric fans on heat transfer. The results show that, the vibrating phase difference of dual fans has nearly no influence on the displacement velocity and amplitude of piezoelectric fan related to single fan once the dimensionless pitch(P/W) is beyond 1.2. The dual piezoelectric fans produce nearly the same peak heat transfer coefficient as that of single fan case.Of particular is that the dual fans operating in-phase produce more favorable heat transfer than the dual fans operating out-of-phase,especially in the gap zone between dual fans. Due to the interaction between dual fans, the streaming flow induced by one vibrating fan suffers the action of sweeping flow of another vibrating fan when they operate out-of-phase. While for the dual fans operating in-phase, the streaming flows induced by vibrating fans merge together to form stronger wall jet flow in the region between two fans.

Electronic physics and possible superconductivity in layered orthorhombic cobalt oxychalcogenides

We suggest that cobalt-oxychalcogenide layers constructed by vertex sharing CoA_2O_2(A = S, Se, Te) tetrahedra, such as BaCoAO, are strongly correlated multi-orbitals electron systems that can provide important clues on the cause of unconventional superconductivity. Differing from cuprates and iron-based superconductors, these systems lack of the D_(4h) symmetry classification. However, their parental compounds possess antiferromagnetic(AFM) Mott insulating states through pure superexchange interactions and the low energy physics near Fermi surfaces upon doping is mainly attributed to the three t_(2g) orbitals that dominate the AFM interactions. We derive a low energy effective model for these systems and predict that a d-wave-like superconducting state with reasonable high transition temperature can emerge by suppressing the AFM ordering even if the pairing symmetry can not be classified by the rotational symmetry any more.

A New Calculation of Rotational Bands in Alpha-Cluster Nuclei

One of the cluster behaviors observed in light nuclei such as20 Ne and44 Ti is the presence of an alpha particle rotating around a double magic number core. In this work, a theoretical method is used for investigation of rotational spectra of two-particle cluster states. To this end, Deng-Fan potential in addition to Hellman potential is used as the core and cluster potential. Next, given the Wildermuth condition, and proper quantum numbers describing the relative motion of the alpha particle and core, the rotational levels of20 Ne and44 Ti isotopes are calculated. Our studies show that the results are in good agreement with the available data.

Superballistic wavepacket spreading in double kicked rotor

We investigate possible ways in which a quantum wavepacket spreads. We show that in a general class of double kicked rotor system, a wavepacket may undergo superballistic spreading; i.e., its variance increases as the cubic of time. The conditions for the observed superballistic spreading and two related characteristic time scales are studied. Our results suggest that the symmetry of the studied model and whether it is a Kolmogorov-Arnold-Moser system are crucial to its wavepacket spreading behavior. Our study also sheds new light on the exponential wavepacket spreading phenomenon previously observed in the double kicked rotor system.