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In the archive of the Ground Wide Angle Camera (GWAC), we found 43 white light flares from 43 stars, among which, three are sympathetic or homologous flares, and one of them also has a quasi-periodic pulsation with a period of $13.0\pm1.5$ minutes. Among these 43 flare stars, there are 19 new active stars and 41 stars that have available TESS and/or K2 light curves, from which we found 931 stellar flares. We also obtained rotational or orbital periods of 34 GWAC flare stars, of which 33 are less than 5.4 days, and ephemerides of three eclipsing binaries from these light curves. Combining with low resolution spectra from LAMOST and the Xinglong 2.16m telescope, we found that $L_{\rm H\alpha}/L_{\rm bol}$ are in the saturation region in the rotation-activity diagram. From the LAMOST medium-resolution spectrum, we found that Star \#3 (HAT 178-02667) has double H$\alpha$ emissions which imply it is a binary, and two components are both active stars. Thirteen stars have flare frequency distributions (FFDs) from TESS and/or K2 light curves. These FFDs show that the flares detected by GWAC can occur at a frequency of 0.5 to 9.5 yr$^{-1}$. The impact of flares on habitable planets was also studied based on these FFDs, and flares from some GWAC flare stars may produce enough energetic flares to destroy ozone layers, but none can trigger prebiotic chemistry on their habitable planets., Comment: 20 pages, 9 figures, 3 tables

The GeSe and SnSe have great potential in nuclear detector devices. Under irradiation, the formation and migration of point defects may affect their properties and performance significantly. In this study, a comparative study of vacancy formation and migration in GeSe and SnSe has been carried out by a first-principles method. It is shown that in both compounds the cation vacancies are generally much easier to form than anion vacancies, and the cation vacancies are generally easier to migrate than anion vacancies. For both Ge vacancy and Sn vacancy, the migration is anisotropic and the [322] direction is the most favorable migration pathway. The migration energy barrier are 0.54 eV for Ge vacancy and 0.46–0.52 eV for Sn vacancy, suggesting that vacancy clusters are relatively easy to form in both compounds, which may influence the application of GeSe and SnSe in nuclear detector devices.

The aggregation of intrinsically disordered proteins is a hallmark of neurodegenerative diseases, such as Alzheimer’s, Parkinson’s and Huntington’s disease. Although we currently have a good molecular level understanding on how protein aggregation occurs in vitro, the details of its self-assembly in live cells are still mainly unknown. During the last ten years, we have witnessed the rapid development of advanced imaging techniques, especially super-resolution and fluorescence lifetime-based microscopy, in different areas of cell biology. These methods have been revolutionising our understanding of how proteins aggregate, providing unprecedented high spatial-temporal resolution which permits us to capture the kinetics of aggregate seeding and expansion, the motion and distribution of individual aggregates within the cells, and its structural change. In this article, we will review the study of in situ protein aggregation using advanced imaging techniques, with the focus on protein aggregate structure and its assembly dynamics.

Bare fiber Bragg grating (FBG) is packaged by thermal conductive materials and to be used as a temperature sensor. In the oil bath calibration of the temperature coefficient of the FBG temperature, it is difficult to accurately synchronize the single point temperature measurement and the simultaneously record FBG central wavelength using different devices. An automatic, fast and high precision calibration method for temperature coefficient of FBG temperature sensor is proposed. The experimental results show that the temperature coefficient obtained by the proposed method can accurately measure the temperature, and the calibration process is fast and avoids the error caused by manual recording and formula derivation. The system is suitable for rapid calibration of mass-produced FBG sensors.

Mammalian target of rapamycin (mTOR) is a protein serine/threonine kinase playing the central downstream role in multiple mitogenic signalling pathways. As a c entral regulator of cell growth, proliferation, differentiation and survival, mTOR has b een reported to modulate proliferation and angiogenesis in neoplastic processes. Curre ntly, sirolimus and its analogues the only five mTOR inhibitors approved for clinical u se, which shows a great capacity in anticancer therapy. However, endocrine resistance in cancer therapy has been observed in sirolimus analogues, and the unavailability of n ew mTOR inhibitor besides similar structure of sirolimus analogues makes the resistan ce even worse. It is urgent to discovery new mTOR inhibitors as candidates for develo pment of effective anticancer drugs. In this study, support vector machine (SVM) as a virtual screening strategy was proposed. SVM models of mTOR inhibitors were constr ucted by training data published before 2012, and the ones published after 2012 as test set were used to verify according to cross validation. The selected model performed thi n false hit rates of 0.12% and 0.46% by screening PubChem and MDDR chemical libr aries respectively. As results, 9 novel novel scaffolds for mTOR were identified, and 6 of them have been reported their anticancer-related therapeutic capacity. In summary, SVM performed its ability to identify novel mTOR inhibitors, which can supply some candidates for mTOR anticancer drugs, and supply effective method for anticancer dru g discovery in future.

With the rapid development of artificial intelligence technology, the application of big data becomes more and more popular in the 21st century. Through unremitting efforts, China has successfully joined the ranks of the big data countries and entered the big data era. However, while people enjoy the convenience of global big data, the problem of intellectual property protection of big data remains to be solved. Based on the analysis of the current situation, difficulties and causes of the intellectual property protection of big data, this paper puts forward the suggestion that the new big data should be an independent object of intellectual property within the framework of the existing intellectual property protection system, in order to provide better protection for big data.

The mechanism governing pile–soil and rock interaction in steeply slipping landslides is quite different from that observed in gently slipping landslides. In particular, the mechanism responsible for the double-row anti-sliding pile stress is notoriously complex. Using the K285 landslide along the Neijiang-Liupanshui railway route as an example in our study, we demonstrated that pile safety in steeply slipping landslides was based on the similarity principle. A physical model interaction test between the double-row anti-sliding piles and the landslide was performed to determine the impact of factors such as the failure mode as well as pile stress, bending moment, and head (top) displacement on the safety of a project site. Herein, we noted that the landslide thrust located behind the lower row was about ½- to 1 times that of the upper row when the distance between two rows of anti-sliding piles was about the same as the pile length, assuming that the same loading conditions were used. Also, the resistance of the sliding mass in front of the upper row piles had a maximum value, and the maximum bending moment of the lower row was about 1 3 - to 1 times that of the upper row under the aforementioned assumptions. The results indicated that the anti-sliding pile heads should be 0.5–1.0 m higher than the ground surface around the piles and backfilled behind the piles. Additionally, the bedrock located before the piles adopted a “wedge” fracture with a depth corresponding to the position of the maximum bending moment. The associated fracture angle and depth were related to the friction angle of the bedrock and the inclination angle of the slipping surface. In conclusion, the study provided insight that will be useful for designing anti-sliding piles to mitigate the occurrence and impact of these types of landslides.

A general framework for observatory control software would help to improve the efficiency of observation and operation of telescopes, and would also be advantageous for remote and joint observations. We describe a general framework for observatory control software, which considers principles of flexibility and inheritance to meet the expectations from observers and technical personnel. This framework includes observation scheduling, device control and data storage. The design is based on a finite state machine that controls the whole process.

High-resolution knee joint vibroarthrographic (VAG) signals can help physicians accurately evaluate the pathological condition of a degenerative knee joint, in order to prevent unnecessary exploratory surgery. Artifact cancellation is vital to preserve the quality of VAG signals prior to further computer-aided analysis. This paper describes a novel method that effectively utilizes ensemble empirical mode decomposition (EEMD) and detrended fluctuation analysis (DFA) algorithms for the removal of baseline wander and white noise in VAG signal processing. The EEMD method first successively decomposes the raw VAG signal into a set of intrinsic mode functions (IMFs) with fast and low oscillations, until the monotonic baseline wander remains in the last residue. Then, the DFA algorithm is applied to compute the fractal scaling index parameter for each IMF, in order to identify the anti-correlation and the long-range correlation components. Next, the DFA algorithm can be used to identify the anti-correlated and the long-range correlated IMFs, which assists in reconstructing the artifact-reduced VAG signals. Our experimental results showed that the combination of EEMD and DFA algorithms was able to provide averaged signal-to-noise ratio (SNR) values of 20.52 dB (standard deviation: 1.14 dB) and 20.87 dB (standard deviation: 1.89 dB) for 45 normal signals in healthy subjects and 20 pathological signals in symptomatic patients, respectively. The combination of EEMD and DFA algorithms can ameliorate the quality of VAG signals with great SNR improvements over the raw signal, and the results were also superior to those achieved by wavelet matching pursuit decomposition and time-delay neural filter.

We evaluate the performance of the first generation scientific CMOS (sCMOS) camera used for astronomical observations. The sCMOS camera was attached to a 25 cm telescope at Xinglong Observatory, in order to estimate its photometric capabilities. We further compared the capabilities of the sCMOS camera with that of full-frame and electron multiplying CCD cameras in laboratory tests and observations. The results indicate the sCMOS camera is capable of performing photometry of bright sources, especially when high spatial resolution or temporal resolution is desired.

We describe the design and construction of a new rapid 3-channel CCD photometer, dedicated to simultaneous multicolor photometric observations of rapidly variable objects. This photometer is equipped on the 1-meter telescope at the Xinglong Observatory. It allows simultaneous imaging within fields of view of 18.8′ × 18.8′, 18.2′ × 17.6′ and 9.2′ × 9.2′ in the Sloan Digital Sky Survey’s g ′, r ′ and i ′ bands, respectively. The results of its calibration and performance are reported.

This paper reports a tunable photonic device that incorporates a thin layer of phase-change material, Ge2Sb2Te5 (GST), in a photonic crystal (PC) structure. The PC structure is based on a one-dimensional grating waveguide with a metal cladding. The metal-cladded PC structure supports a guided-mode resonance (GMR) that selectively absorbs light at a particular wavelength. Inserting the GST material into the gating waveguide makes it possible to control the GMR mode. Here, the GST-PC device was numerically designed and optimized to obtain significant tuning of the GMR mode around 1550 nm. The tuning phenomena were experimentally demonstrated by the heat-induced phase change between crystalline and amorphous phases of the GST thin film. A spectral shift of the resonant wavelength from 1440 to 1610 nm was achieved via the crystallization process. The phase tuning of GST exhibits good repeatability as demonstrated by switching between amorphous and crystalline phases of GST for multiple cycles. The GST-PC device represents a new approach for tuning optical resonances with potential applications including but not limited to integrated photonic circuits, optical communications, and high-performance optical filters.

The normal displacement and pressure of Scholte and Leaky Rayleigh waves at air–metal interface generated by a pulsed disc-like source are simulated theoretically by the Cagniard–de Hoop method and studied by laser ultrasound technique experimentally. It is found that the Scholte wave detected by a photorefractive interferometer is mainly contributed by the surface pressure and the Leaky Rayleigh wave is dominated by the surface displacement. It is also proven that the pulse width of these interface waves is mainly determined by the acoustic time delay on the generating source size under our experimental conditions.

A two-dimensional theoretical model is used to analyse the acoustic field of cylindrical surface waves generated by a pulsed laser line source in the ablation regime. The complete dispersive curves for cylindrical Rayleigh wave are presented. The laser-generated transient acoustic field of cylindrical Rayleigh waves is calculated and the corresponding laser ultrasonic experiments are carried out. Both the numerical and experimental results are in good agreement.

We experimentally investigate the transparent-liquid/solid (water/aluminum or steel) interface waves generated by laser pulses and detected by the Mirage effect. It is shown that nearly all kinds of liquid/solid interface waves in water are detected, both their measured wave velocities and characteristic of shape are in good agreement with theoretical predictions.

SONG is a global ground based network of 1 meter telescopes for stellar time-domain science, an international collaboration involving many countries across the world. In order to enable a favourable duty cycle, the SONG network plans to create a homogeneous distribution of 4 nodes in each of the northern and southern hemispheres. A natural possibility was building one of the northern nodes in East Asia, preferably on the Qinghai-Tibetan Plateau. During the last decade, a great deal of effort has been invested in searching for high a quality site for ground based astronomy in China, since this has been one of the major concerns for the development of Chinese astronomy. A number of sites on the plateau have been in operation for many years, but most of them are used only for radio astronomy, as well as small optical telescopes for applied astronomy. Several potential sites for large optical instruments have been identified by the plateau site survey, but as yet none of them have been adequately quantitatively characterised. Here we present results from a detailed multi-year study of the Delingha site, which was eventually selected for the SONG-China node. We also describe the site monitoring system that will allow an isolated SONG and 50BiN node to operate safely in an automated mode., 30 pages, 15 figures

This paper presents the fabrication methodology of a linear variable photonic crystal (PC) filter with narrowband reflection that varies over a broad spectral range along the length of the filter. The key component of the linear variable PC filter is a polymer surface-relief grating whose period changes linearly as a function of its position on the filter. The grating is fabricated using a nanoreplica molding process with a wedge-shaped elastomer mold. The top surface of the mold carries the grating pattern and the wedge is formed by a shallow angle between the top and bottom surfaces of the mold. During the replica molding process, a uniaxial force is applied to stretch the mold, resulting in a nearly linearly varying grating period. The period of the grating is determined using the magnitude of the force and the local thickness of the mold. The grating period of the fabricated device spans a range of 421.8-463.3 nm over a distance of 20 mm. A high refractive index dielectric film is deposited on the graded-period grating to act as the waveguide layer of the PC device. The resonance reflection feature of the device varies linearly in a range of 680.2-737.0 nm over the length of the grating.

Guided-mode resonance (GMR) structures consisting of sub-wavelength periodic gratings are capable of producing narrow-linewidth optical resonances. This paper describes a sol-gel-based imprint lithography method for the fabrication of submicron 1D and 2D GMR structures. This method utilizes a patterned polydimethylsiloxane (PDMS) mold to fabricate the grating coupler and waveguide for a GMR device using a sol-gel thin film in a single step. An organic-inorganic hybrid sol-gel film was selected as the imprint material because of its relatively high refractive index. The optical responses of several sol-gel GMR devices were characterized, and the experimental results were in good agreement with the results of electromagnetic simulations. The influence of processing parameters was investigated in order to determine how finely the spectral response and resonant wavelength of the GMR devices could be tuned. As an example potential application, refractometric sensing experiments were performed using a 1D sol-gel device. The results demonstrated a refractive index sensitivity of 50 nm/refractive index unit. This one-step fabrication process offers a simple, rapid, and low-cost means of fabricating GMR structures. We anticipate that this method can be valuable in the development of various GMR-based devices as it can readily enable the fabrication of complex shapes and allow the doping of optically active materials into sol-gel thin film.

The acoustic propagation characteristics of a finite one-dimensional water-glass phononic crystal (PC) are studied using the Schlieren visualization method, which is fast and non-invasive. The band structures of this PC are measured experimentally with continuous acoustic waves incident on it using the Schlieren method, and the results are highly consistent with the theoretical calculations. The dynamic acoustic field in the PC at different frequencies is imaged and the resonance phenomena in the components of the PC are observed. The results show that the Schlieren method is an effective means of studying the interactions between acoustic waves and PCs.

Transient currents associated with electroforming TiO2-based resistive switching devices were measured using three distinct circuits designed to limit them, and they were correlated with physical changes in the top electrode using scanning electron microscopy. A transient current more than 10 times greater than expected was observed when only using the source meter to limit the current via the compliance set point. The large excursion arose from equipment delays and resulted in significant physical changes to the top electrode. An external resistor was used to decrease the excess transient current value to nearly zero, as long as parasitic capacitive discharges were also suppressed. Simultaneously, the physical changes to the top electrode were completely suppressed, indicating physical damage was related to Joule heating from the excess forming currents. The switching characteristics of all devices were similar, implying damage during electroformation of functional switches can be avoided by device/circuit design.

Temperature distributions in Pt/SrZrO3/SrRuO3 and Pt/TiO2/Pt thin film heterostructures were imaged by infrared thermography while under electrical bias. Local hot spots with lateral sizes between 5 and 30 µm appear during electroforming, they reappear during switching, and they show temperature increases from 50 to above 250 °C. Over 90% of conductivity increases produced by electroforming were confined to the hotspot locations. In some structures, thermography demonstrated that two separate conductive paths could be formed using opposite biases, and their conductivities could be repeatedly switched on and off with opposite voltage dependences. Direct evidence of large temperature increases supports the existence of Joule heating within the conductive channel during resistance switching of oxide heterostructures.

Based on the interaction mechanism between tip and sample in the contact mode of a scanning probe acoustic microscope (SPAM), an active mass of the sample is introduced in the mass-spring model. The tip motion and frequency response of the sample vibration mode in the SPAM are calculated by the Lagrange equation with dissipation function. For the silicon tip and glass assemblage in the SPAM the frequency response is simulated and it is in agreement with the experimental result. The living myoblast cells on the glass slide are imaged at resonance frequencies of the SPAM system, which are 20kHz, 30kHz and 120kHz. It is shown that good contrast of SPAM images could be obtained when the system is operated at the resonance frequencies of the system in high and low-frequency regions.