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Synchronization and frequency locking between remote mechanical oscillators are of scientific and technological importance. The key challenges are to align the oscillation frequencies and realize strong nonlinear interaction of both oscillators to a common carrier capable of long-distance transmission. Here, we experimentally realize the all-optical synchronization between two different optomechanical systems, a microsphere and a microdisk. The mechanical oscillation of the microsphere induced by the radiation pressure is loaded onto the pump laser via the optomechanical interaction, which is directly transmitted through a 5-km-long single-mode fiber to excite the mechanical oscillation of the microdisk. By finely tuning both the optical and mechanical frequencies of the two microresonators, the oscillation of the microdisk is injection locked to the microsphere, resulting in a synchronized phase relation of the two systems. Our results push a step forward the long-distance synchronization network using optomechanical microresonators.

Mechanical degrees of freedom, which have often been overlooked in various quantum systems, have been studied for applications ranging from quantum information processing to sensing. Here, we develop a hybrid platform consisting of a magnomechanical cavity and an optomechanical cavity, which are coherently coupled by the straightway physical contact. The phonons in the system can be manipulated either with the magnetostrictive interaction or optically through the radiation pressure. Together with mechanical state preparation and sensitive readout, we demonstrate the microwave-to-optical conversion with an ultrawide tuning range up to 3 GHz. In addition, we observe a mechanical motion interference effect, in which the optically driven mechanical motion is canceled by the microwave-driven coherent motion. Manipulating mechanical oscillators with equal facility through both magnonic and photonic channels enables new architectures for signal transduction between the optical, microwave, mechanical, and magnetic fields.

A scheme for observing photon blockade in a single bosonic mode with weak nonlinearity is proposed and numerically verified. Using a simple bi-tone drive, sub- and super-Poissonian light can be generated with high fidelity. With a periodically poled lithium niobate microcavity, a sub-Poissonian photon source with kHz count rate can be realized. Our proposed scheme is robust against parameter variations of the cavity and extendable to any bosonic system with anharmonic energy levels.

Background Aim of this multicenter, observational, cross-sectional study was to evaluate health-related quality of life (HRQoL) and treatment satisfaction of current medications in Chinese knee OA patients. Methods Brief Pain Inventory (BPI), Treatment Satisfaction Questionnaire (TSQM-1.4), and HRQoL (EQ-5D-5L) were assessed in total of 601 OA of knee patients. Impact on QoL (EQ-5D-5L) and treatment satisfaction (TSQM-1.4) by BPI-Severity score ( Results Mean score of EQ-5D-5L of patients with BPI-Severity ≥4 was significantly lower than those with BPI-Severity Conclusion Chronic knee OA pain has a significant impact on patients’ HRQoL. More severe patients with OA were less satisfied with current treatments.

Thin-film gallium nitride (GaN) is a promising platform for phononic integrated circuits that hold great potential for scalable information processing processors. Here, an unsuspended traveling phononic resonator based on a high-acoustic-index-contrast mechanism is realized in GaN-on-Sapphire with a frequency up to 5 GHz, which matches the typical superconducting qubit frequency. A sixfold increment in quality factor is found when temperature decreases from room temperature ( Q = 5000) to [Formula: see text] ( Q = 30 000), and thus, a frequency-quality factor product of [Formula: see text] is obtained. Higher quality factors should be available when the fabrication process is further optimized. Our system shows great potential in hybrid quantum devices via the so-called circuit quantum acoustodynamics.

Ultra-high resolution mass sensing used to be realized by measuring the changed mechanical oscillation frequency by a small mass that should be detected. In this work we present a different approach of mass sensing without directly measuring such mechanical frequency change but relying on the modified light field due to a previously less explored nonlinear mechanism of optomechanical interaction. The concerned optomechanical setup used for the mass sensing is driven by a sufficiently strong two-tone field satisfying a condition that the difference of these two drive frequencies matches the frequency of the mechanical oscillation, so that a nonlinear effect will come into being and lock the mechanical motion under the radiation pressure into a series of fixed orbits. A small mass attached to the mechanical resonator slightly changes the mechanical frequency, thus violating the exact frequency match condition. Such small change can be detected by the amplitude modification on the higher order sidebands of the cavity field. Even given a moderate mechanical quality factor for the setup, the added mass can still be detected to the levels corresponding to a mechanical frequency shift from 5 to 7 order less than the mechanical damping rate. Because the output cavity field difference for very close values of mechanical frequency is not blurred by thermal noise, such mass sensing can be well performed at room temperature. The previous tough requirements for ultra-high resolution mass sensing can be significantly relaxed by the method.

Unsuspended phononic integrated circuits have been proposed for on-chip acoustic information processing. Limited by the operation mechanism of a conventional interdigital transducer, the excitation of the quasi-Love mode in GaN-on-sapphire is inefficient, and thus, a high-efficiency Rayleigh-to-Love mode converter is of great significance for future integrated phononic devices. Here, we propose a high-efficiency and robust phononic mode converter based on an adiabatic conversion mechanism. Utilizing the anisotropic elastic property of the substrate, the adiabatic mode converter is realized by a simple tapered phononic waveguide. A conversion efficiency exceeding 96% with a [Formula: see text] bandwidth of [Formula: see text] can be realized for phononic waveguides working at GHz frequency band, and excellent tolerance to the fabrication errors is also numerically validated. The device that we proposed can be useful in both classical and quantum phononic information processing, and the adiabatic mechanism could be generalized to other phononic device designs.

The purpose of the present investigation is to reveal the primary resonance of a rotating pretwisted blade subject to a flapwise natural frequency gas excitation under thermal gradient in the presence of 2:1 internal resonance. The linear part of the dynamic model can be decoupled via the modal analysis. The method of multiple scales is applied to seek the steady-state responses. The stabilities of the responses are analyzed via the Lyapunov theory. Amplitude-frequency relationships are examined with the focus on the effects of thermal gradient, pre-deformation amplitude, rotating speed, gas pressure and damping coefficients. Plotting the response amplitudes as a function of the gas pressure amplitude exhibits the saturation and the jump phenomena in rotating blade. Colored distributions in resonance parameters plane demonstrate the occurrences of the saturation and the jump phenomena. The regions of stability and instability of the steady-state are presented in the plane of the gas pressure amplitude and the external excitation frequency tune. Detailed analysis is performed on an unstable region of the rotating blade. The analysis indicates the existence of quasi-periodic motion identified by time history, phase plane trajectories and Poincare sections. The numerical results show a good agreement with the available analytical solutions.

Here in this report, Xanthoceras sorbifolia seed coats are selected to prepare porous carbons. Biochar is first prepared by dry distillation of the seed coats, and then is transformed into porous carbon by KOH activation. The regulation of activation temperatures and ratios of activator is studied. The optimized condition is activation temperature of 750 °C, and the ratio of biochar to activator is 1:3. HRTEM, X-ray diffraction and the Brunauer-Emmett-Teller methods were used to characterize the samples. The porous carbon prepared under the optimum condition has a specific surface area of 2148 m2 g−1 with a large amount of micropores of about 0.5 nm–2 nm closely and orderly distributed, together with a certain number of mesporous (~12% of the total specific surface area), such a unique structure provides both a large storage space for electrons and a channel for them to passage quickly. Due to this unique architecture, the specific capacitance of the porous carbon is as high as 421 F/g at a current density of 0.5 A/g, with a moderate rate capability (259 F/g at 10 A/g), and good cycle stability (90.7% capacitance retention after 5000 cycles at 10 A/g), suggesting it one of the ideal materials for the development of supercapacitors. Symmetrical supercapacitor based on this material has also been assembled and tested to further verify the actual capacitance properties. The specific capacitance of the symmetrical supercapacitor is 276 F/g at 0.5 A/g, and 50 F/g was achieved when the current density was raised up to 10 A/g. Under the current density of 10 A/g, the capacitance only decreased slightly after the circulation of 5000 cycles, and the retention rate reached 86%, illustrates the practical application potential of this material.

In an optomechanical system, we experimentally engineer the optical density of state to reduce or broaden the effective linewidth of the optical mode by introducing an ancillary mechanical mode, which has a large decay rate, i.e., stimulated backward Brillouin scattering. Based on this dissipation engineering, we could engineer the optical mode linewidth by one order of magnitude. In addition, we can either enhance or suppress the optomechanical cooling and amplification of the target mechanical oscillations. Our scheme demonstrates the cascaded photon-phonon coupling to control the mechanical interactions, and also presents a novel approach for engineering coherent light-matter interaction in hybrid systems, which consist of different types of nonlinear interactions and multiple modes, and promote the performance of quantum devices.

Background: Aim of this multicenter, observational, cross-sectional study was to evaluate health-related quality of life (HRQoL) and treatment satisfaction of current medications in Chinese knee OA patients. Methods: Brief Pain Inventory (BPI), Treatment Satisfaction Questionnaire (TSQM-1.4), and HRQoL (EQ-5D-5L) were assessed in total of 601 OA of knee patients. Impact on QoL (EQ-5D-5L) and treatment satisfaction (TSQM-1.4) by BPI-Severity score (Results: Mean score of EQ-5D-5L of patients with BPI-Severity ≥4 was significantly lower than those with BPI-Severity Conclusion: Chronic knee OA pain has a significant impact on patients’ HRQoL. More severe patients with OA were less satisfied with current treatments. Trial registration (Clinical Trials identifier): Not applicable

With advanced micro- and nano-photonic structures, the vacuum photon-photon coupling rate is anticipated to approach the intrinsic loss rate and lead to unconventional quantum effects. Here, we investigate the classical-to-quantum transition of such photonic nonlinear systems using the quantum cluster-expansion method, which addresses the computational challenge in tracking large photon number states of the fundamental and harmonic optical fields involved in the second harmonic generation process. Compared to the mean-field approximation used in weak coupling limit, the quantum cluster-expansion method solves multimode dynamics efficiently and reveals the quantum behaviors of optical parametric oscillations around the threshold. This work presents a universal tool to study quantum dynamics of multimode systems and explore the nonlinear photonic devices for continuous-variable quantum information processing., Comment: 7 pages, 6 figures

Coherent conversion of microwave and optical photons can significantly expand the ability to control the information processing and communication systems. Here, we experimentally demonstrate the microwave-to-optical frequency conversion in a magneto-optical whispering gallery mode microcavity. By applying a magnetic field parallel to the microsphere equator, the intra-cavity optical field will be modulated when the magnon is excited by the microwave drive, leading to microwave-to-optical conversion via the magnetic Stokes and anti-Stokes scattering processes. The observed single sideband conversion phenomenon indicates a non-trivial optical photon-magnon interaction mechanism, which is derived from the magnon induced both the frequency shift and modulated coupling rate of optical modes. In addition, we demonstrate the single-sideband frequency conversion with an ultrawide tuning range up to 2.5GHz, showing its great potential in microwave-to-optical conversion., Comment: 6 pages, 4 figures

Single-photon transport in non-ideal chiral photon-atom interaction structures generally contains information backflow and thus limits the capabilities to transfer information between distant emitters in cascaded quantum networks. Here, in the non-ideal chiral case, a V -type atom coupled to a waveguide is proposed to realize completely unidirectional transmission of the single photons in a superposition state of different frequencies. A microwave field is introduced to drive the two excited states of the atom and results in photon conversion between two transitions. By adjusting the Rabi frequency and the phase of the external driving field, the transport behaviors of incident photons with specific frequencies can be optimized to complete transmission or reflection. Based on the constructive interferences between photons from different traveling paths, the transmission probabilities of the specific-frequency photons could be enhanced. Due to photon conversions with compensating the dissipations and ensuring the complete destructive interference, the ideal unidirectional transmission contrast can be maintained to 1, even when the atom has dissipations into the non-waveguide modes., 8 pages, 6 figures

The quantum logic between single photons lies at the foundation of deterministic, scalable quantum information processing. However, practical implementation suffers from weak optical nonlinearity, and gate fidelity is intrinsically limited by phase noise and spectral mixing. The authors address these concerns by utilizing an ultrahigh-$Q$ photonic microcavity with ${\ensuremath{\chi}}^{2}$ nonlinearity. Two-photon spontaneous emission is thoroughly suppressed by shutting off the coupling channels between this artificial atom and the continuum states of a waveguide. This promising scheme for room-temperature operation is almost within reach of current experiments, and can be generalized to other systems.

We propose how to achieve nonreciprocal quantum entanglement of light and motion and reveal its counterintuitive robustness against random losses. We find that by splitting the counterpropagating lights of a spinning resonator via the Sagnac effect, photons and phonons can be entangled strongly in a chosen direction but fully uncorrelated in the other. This makes it possible both to realize quantum nonreciprocity even in the absence of any classical nonreciprocity and also to achieve significant entanglement revival against backscattering losses in practical devices. Our work provides a way to protect and engineer quantum resources by utilizing diverse nonreciprocal devices, for building noise-tolerant quantum processors, realizing chiral networks, and backaction-immune quantum sensors.

We propose a scheme for controlling the quantum interface between the travelling optical wave packet and microwave photonic memory. The effective coupling between the optical and microwave modes is mediated by the rare earth doped crystal as first proposed by Williamson et al. [L.A. Williamson, Y.H. Chen, J.J. Longdell, Phys. Rev.Lett. 113, 203601 (2014)], and can be modulated by a time-dependent coherent driving field. With the effective model, we obtain the fidelity of the write process for arbitrary input wave packet as well as driving field, and investigate its optimization in two cases. In the first case of constant coupling, the optimal input wave packet is analytically derived to maximize the fidelity, while in the latter case of tunable coupling, the sequence of coherent driving field is numerically optimized for arbitrary given input wave packet. The write process for the Gaussian input wave packet can be explicitly characterized in the tunable parameter regime of real experiments, revealing that the fidelity can reach 0.974η (η being the coupling efficiency of the optical cavity). Based on these advantages, the proposal will have potential applications for the investigation of quantum networks.

With digital satellite remote sensing image data of GF-1,in 2018 the object-oriented classification method was used to extract Zizyphus jujuba planting area in Jia county of Shaanxi province. The results showed that the remote sensing classification method based on rule set could extract and reckon Z. jujube planting area in the study area effectively. The planting area of Z. jujube in Jia county was about 5. 34×104 hm2 and the area of consistent accuracy was 97. 92%. The method used in this study could provide a technical reference for the area extraction of the same type of medicinal materials. And it is of great significance to provide decision support for the protection and utilization of Z. jujube resources.

We propose an efficient scheme for implementing the universal controlled-phase gate with logical qubits encoded in the superpositions of $2d$ circularly distributed coherent states ($d$ is a positive integer), which have the advantage of protecting quantum information against the $(d\ensuremath{-}1)$-photon loss errors. We first demonstrate explicitly how to engineer dispersive interaction between the microwave cavity modes and multilevel transmon ancilla in circuit quantum electro-dynamical (QED) system. With the cat-state qubits, we realize the two-qubit controlled phase gate, and its operation time scales as $1/d$. This means that it will be less susceptible to environmental disturbances if we employ larger $d$ to encode information. Finally, we employ the experimentally reachable parameters in circuit QED system to numerically study the influence of the photon loss, the qubit relaxation, and the Kerr nonlinearity. The average fidelity for a controlled-phase gate has reached 0.9955 for $d=8$ when the system imperfections are considered. The results demonstrate the great potential of our scheme for quantum computation in circuit QED system.

Non-reciprocal devices, which allow the non-reciprocal signal routing, serve as the fundamental elements in photonic and microwave circuits and are crucial in both classical and quantum information processing. The radiation-pressure-induced coupling between light and mechanical motion in traveling wave resonators has been exploited to break the Lorentz reciprocity, realizing non-reciprocal devices without magnetic materials. Here, we experimentally demonstrate a reconfigurable nonreciprocal device with alternative functions of either a circulator or a directional amplifier via the optomechanically induced coherent photon-phonon conversion or gain. The demonstrated device exhibits considerable flexibility and offers exciting opportunities for combining reconfigurability, non-reciprocity and active properties in single photonic structures, which can also be generalized to microwave as well as acoustic circuits., 13 pages, 4 Figures

We propose an optomechanical dissipation engineering scheme by introducing an ancillary mechanical mode with a large decay rate to control the density of states of the optical mode. The effective linewidth of the optical mode can be reduced or broadened, manifesting the dissipation engineering. To prove the ability of our scheme in improving the performances of the optomechanical system, we studied optomechanical entanglement and phonon cooling. It is demonstrated that the optomechanical entanglement overwhelmed by thermal phonon excitations could be restored via dissipation engineering. For the phonon cooling, an order of magnitude improvement could be achieved. Our scheme can be generalized to other systems with multiple bosonic modes, which is experimentally feasible with advances in materials and nanofabrication, including optical Fabry-Perot cavities, superconducting circuits, and nanobeam photonic crystals., 8 pages, 6 figures

Synthetic gauge fields have recently emerged, arising in the context of quantum simulations, topological matter, and the protected transportation of excitations against defects. For example, an ultracold atom experiences a light-induced effective magnetic field when tunnelling in an optical lattice, and offering a platform to simulate the quantum Hall effect and topological insulators. Similarly, the magnetic field associated with photon transport between sites has been demonstrated in a coupled resonator array. Here, we report the first experimental demonstration of a synthetic gauge field in the virtual dimension of bosonic modes in a single optomechanical resonator. By employing degenerate clockwise (CW) and counter-clockwise (CCW) optical modes and a mechanical mode, a controllable synthetic gauge field is realized by tuning the phase of the driving lasers. The non-reciprocal conversion between the three modes is realized for different synthetic magnetic fluxes. As a proof-of-principle demonstration, we also show the dynamics of the system under a fast-varying synthetic gauge field. Our demonstration not only provides a versatile and controllable platform for studying synthetic gauge fields in high dimensions but also enables an exploration of ultra-fast gauge field tuning with a large dynamic range, which is restricted for a magnetic field., Comment: 6 pages, 3 figures

Objective To observe pilots with asymptomatic cerebral infarction (ACI) for their short-term prognosis. Methods Twenty-two pilots who were diagnosed having ACI by magnetic resonance imaging were enrolled in this study. When they returned to the hospital for regular reexamination, the number of ACI foci , the incidents of acute cerebrovascular disease and grounding of aircraft for any reasons were recorded. According to whether the ACI lesions increased, the patients were divided into two groups. The risk factors for cerebral vascular disease were compared between the two groups. Results All the patients were followed for 6-42 months (mean 14.18±8.55 months), and 6(18.18%) patients were found to have increase of lesions. No neurological deficit was seen in the two groups, although 3 flight crews were grounded for non-ACI reason. Age and flight time showed statistically significant differences between the lesions increased group and no lesion increased group. Conclusions The number of ACI foci of some pilots may increase, which is affected by age and flight time. Further investigations on the long-term prognosis and the impacts on flight are needed. DOI: 10.11855/j.issn.0577-7402.2016.09.16

Non-reciprocal devices, such as circulators and isolators, are indispensable components in classical and quantum information processing in an integrated photonic circuit. Aside from those applications, the non-reciprocal phase shift is of fundamental interest for exploring exotic topological photonics, such as the realization of chiral edge states and topological protection. However, incorporating low optical-loss magnetic materials into a photonic chip is technically challenging. In this study, we experimentally demonstrate non-magnetic non-reciprocity using optomechanical interactions in a whispering-gallery microresonator, as proposed by Hafezi and Rabl. Optomechanically induced non-reciprocal transparency and amplification are observed, and a non-reciprocal phase shift of up to 40 degrees is demonstrated in this study. The results of this study represent an important step towards integrated all-optical controllable isolators and circulators, as well as non-reciprocal phase shifters., 5 pages, 4 Figures

A highly efficient organocatalytic one-pot enantioselective synthesis of (R)-2-aryl-2,3-dihydro-4-quinolones from o-aminoacetophenones and aryl aldehydes has been developed. The approach is characterized by being metal free, solvent free and protecting group free. A variety of 2-aryl-2,3-dihydro-4-quinolones could be obtained in good yields up to 99% ee.

Nonlinear optical effects in integrated microcavities have been studied extensively with the advantages of strong light-matter interaction, great scalability, and stability due to the small mode volume. However, the pump lasers stimulating nonlinear effects impose obstacles for practical applications, since the material absorption causes thermal resonance drift and instability. Here we experimentally demonstrate an all-optical control of the thermal behavior in optical microcavities for tunable doubly-resonant second-harmonic (SH) generation on an integrated photonic chip. Through an auxiliary control laser, the temperature of a selected microring can be efficiently changed, thus allowing precise frequency tuning of the doubly-resonant wavelength while eliminating the distortion of the lineshape induced by the thermo-optic effect. Although the phase-matching conditions will limit the tuning range of 55GHz, the technique is still potential to achieve a larger tuning range in combination with temperature regulation. Additionally, this approach has the advantage of quick reconfiguration, showing a fast modulation rate up to about 256 kHz. The theoretical model behind our experimental scheme is universal and applicable to other microcavity-enhanced nonlinear optical processes, and our work paves the way for controlling and utilizing the thermal effect in the applications of microcavities.

The quantum spin states of atomic ensemble are of special interesting for both fundamental studies and precision measurement applications. Here, we propose a scheme to prepare collective quantum states of an atomic ensemble placed in an optical cavity via homodyne measurement of probing light field. The effective interactions of atoms mediated by photons are enhanced by the optical cavity, and the output probe light could also be entangled with the collective spin states. By selectively measuring the quadrature of output light, we can prepare various quantum states, including superposition states of Dicke states and Dicke squeezed states. It is also demonstrated that the fidelity of prepared quantum state can be enhanced by repetitive homodyne detection and using longer probe laser pulses. Our scheme is feasible for experimental realization with current technologies, which may be used in future study of quantum mechanics and quantum metrology., Comment: 7 pages, 4 figures

We experimentally demonstrate a reconfigurable non-reciprocal device with alternative functions as either a circulator or a directional amplifier via optomechanically induced coherent photon-phonon conversion or gain.

We propose an experimental feasible scheme for implementing two-qubit quantum phase gate with atoms trapped in an optical cavity. The scheme is based on the dispersive interaction between the optical cavity mode and the three-level atoms in Λ configuration, which has been demonstrated in recent cavity-induced spin squeezing experiment (Leroux et al., 2010) [26] . We also discuss the influence of the cavity decay on the gate fidelity. It is shown that the fidelity of the phase gate is robust to the cavity decay and the high-fidelity quantum phase gate can be implemented with the current experimental technology.

We theoretically study the unique applications of optomechanics based on traveling-wave microresonators, where the optomechanical coupling of degenerate modes can be enhanced selectively by optically pumping in different directions. We show that the unique features of degenerate optical modes can be applied to the entangled photon generation of clockwise and counter-clockwise optical modes, and the nonclassicality of entangled photon pair is discussed. The coherent coupling between the clockwise and counter-clockwise optical mods and two acoustic modes is also studied, in which the relative phase of the optomechanical couplings plays a key role in the optical non-reciprocity. The parity-time symmetry of acoustic modes can be observed in the slightly deformed microresonator with the interaction of forward and backward stimulated Brillouin Scattering in the triple-resonance system. In addition, the degenerate modes are in the decoherence-free subspace, which is robust against environmental noises. Based on parameters realized in recent experiments, these optomechanical devices should be readily achievable., 9 pages, 5 figures

In dealing with the characteristics of the air field, a dogfight threat assessment method based on cloud model is proposed, the method can make full use of the target information, comprehensively takes the qualitative and quantitative factors into the consideration, and achieves the qualitative concept of value and the number of natural transformation between quantitative values, improves the precision of the dogfight threat assessment.

A phase-controlled ultralow-threshold phonon laser is proposed by using tunable optical amplifiers in coupled-cavity-optomechanical system. Giant enhancement of coherent photon-phonon interactions is achieved by engineering the strengths and phases of external parametric driving. This in turn enables single-photon optomechanics and low-power phonon lasing, opening up novel prospects for applications, e.g. quantum phononics and ultrasensitive motion detection., Comment: 10 pages, 5 figures

A method of multiple scales is developed for n-degree-of-freedom weakly nonlinear gyroscopic systems. A general procedure is proposed to establish solvability conditions. The conditions have n different versions whose equivalence cannot be mathematically demonstrated. The procedure is applied to a 4-degree-of-freedom nonlinear gyroscopic system that is the 4-term Galerkin truncation of the governing equation of a pipe conveying fluid flowing in the supercritical speed. The investigation focuses on the primary external resonance in the first frequency ω1 and the two-to-one internal resonance of the first two frequencies ω1 and ω2. The multi-scale analysis shows that the amplitude–frequency response curve in each of the first two modes has a peak bending to the left when ω2>2ω1, two peaks with the same height and the opposite bending directions when ω2=2ω1, and a peak bending to the right when ω2

Although class D amplifier has the merits of high efficiency, a little heat and small Bulk, its distortion is larger than linear counterparts due to switching behaviour of power transistors. Its principle and several new pivotal control technologies were presented in this paper. In this way, efficiency of 90% can be achieved and the degree of the distortion can be less than 0.4%.

A new family of organocatalysts based on aminoquinoline and pyrrolidine have been developed and shown to catalyze the direct and highly enantioselective cyclization of 2′-hydroxychalcones in imitation of the natural process of chalcone cyclization. The straightforward synthetic process occurs under mild reaction conditions, tolerates moisture and air, and gives an enantiomeric excess up to 99%. This approach provides a facile and efficient access to chiral flavanones.

A general and efficient palladium-catalyzed intermolecular direct C-2 alkenylation of indoles using oxygen as the oxidant has been developed. The reaction is of complete regio- and stereoselectivity. All products are E-isomers at the C-2-position with no Z-isomers and 3-substituted products were detected.

An efficient and economical palladium-catalyzed oxidation system has been identified. The oxidation system, characterized by not adding ligand and using molecular oxygen as the sole oxidant, can realize the Tsuji-Wacker oxidation of terminal olefins and especially styrenes to methyl ketones; in addition, this system can achieve tandem Wacker oxidation-dehydrogenation of terminal olefins to α,β-unsaturated ketones.

Non-linear vibration of viscoelastic pipes conveying fluid around curved equilibrium due to the supercritical flow is investigated with the emphasis on steady-state response in external and internal resonances. The governing equation, a non-linear integro-partial-differential equation, is truncated into a perturbed gyroscopic system via the Galerkin method. The method of multiple scales is applied to establish the solvability condition in the first primary resonance and the 2:1 internal resonance. The approximate analytical expressions are derived for the frequency–amplitude curves of the steady-state responses. The stabilities of the steady-state responses are determined. The generation and the vanishing of a double-jumping phenomenon on the frequency–amplitude curves are examined. The analytical results are supported by the numerical integration results.