Micrometer-precision absolute distance measurement with a repetition-rate-locked soliton microcomb.

The soliton microcomb has sparked interest in high-precision distance measurement, owing to its ultrahigh repetition rate and chip-integrated scale. We report absolute distance measurements based on synthetic wavelength interferometry with a soliton microcomb. We stabilized the repetition rate of 48.98 GHz through injection locking, with fluctuations below 0.25 Hz. Distance measurements up to 64 mm were demonstrated, presenting residuals below 2.7 µm compared with a referenced laser interferometer. Long-term distance measurements were made at two fixed positions of approximately 0.2 m and 1.4 m, resulting in a minimum Allan deviation as low as 56.2 nm at an average time of 0.05 s. The dynamic demonstration illustrated that the proposed system could track round-trip motion of 3 mm at speeds up to 100 mm/s. The proposed distance measurement system is, to our knowledge, the first microcomb-based synthetic wavelength interferometer and achieves a ranging precision of tens of nanometers, with potential applications in the fields of satellite formation flying, high-end manufacturing, and micro-nano processing.

A Centimeter-Scale Dielectric Metasurface for the Generation of Cold Atoms.

The single-beam magneto-optical trap (MOT) based on the diffractive optical element offers a new route to develop compact cold atom sources. However, the optical efficiency in the previous single-beam MOT systems is usually low and unbalanced, which will affect the quality of the trapped atoms. To solve this issue, we developed a centimeter-scale dielectric metasurface optical chip with dynamic phase distributions, which was used to split a single incident laser beam into five separate ones with well-defined polarization states and uniform energy distributions. The measured diffraction efficiency of the metasurface is up to 47%. A single-beam MOT integrated with the metasurface optical chip was then used to trap the 87Rb atoms with numbers ∼1.4 × 108 and temperatures ∼7.0 µK. The proposed concept in this work may provide a promising solution for developing ultracompact cold atom sources.

Thin-Copper-Layer-Induced Early Fracture in Graphene-Nanosheets (GNSs)-Reinforced Copper-Matrix-Laminated Composites.

The strength-ductility trade-off has been a long-standing challenge when designing and fabricating a novel metal matrix composite. In this study, graphene-nanosheets (GNSs)-reinforced copper (Cu)-matrix-laminated composites were fabricated through two methods, i.e., the alternating electrodeposition technique followed by spark plasma sintering (SPS) and direct electrodeposition followed by hot-press sintering. As a result, a Cu-GNS-Cu layered structure formed in the composites with various Cu layer thicknesses. Compared with the pure Cu, the yield strength of the GNS/Cu composites increased. However, the mechanical performance of the GNS/Cu composites was strongly Cu-layer-thickness-dependent, and the GNS/Cu composite possessed a brittle fracture mode when the Cu layer was thin (≤10 µm). The fracture mechanism of the GNS/Cu composites was thoroughly investigated and the results showed that the premature failure of the GNS/Cu composites with a thin Cu layer may be due to the lack of Cu matrix, which can relax the excessive stress intensity triggered by GNSs and delay the crack connection between neighboring GNS layers. This study highlights the soft Cu matrix in balancing the strength and ductility of the GNS/Cu-laminated composites and provides new technical and theoretical support for the preparation and optimization of other laminated metal matrix composites.

Robust single-sideband-modulated Raman light generation for atom interferometry by FBG-based optical rectangular filtration.

Low-phase-noise and pure-spectrum Raman light is vital for high-precision atom interferometry by two-photon Raman transition. A preferred and prevalent solution for Raman light generation is electro-optic phase modulation. However, phase modulation inherently brings in double sidebands, resulting in residual sideband effects of multiple laser pairs beside Raman light in atom interferometry. Based on a well-designed rectangular fiber Bragg grating and a plain electro-optic modulator, optical single-sideband modulation has been realized at 1560 nm with a stable suppression ratio better than -25 dB despite of intense temperature variations. After optical filtration and frequency doubling, a robust phase-coherent Raman light at 780 nm is generated with a stable SNR of better than -19 dB and facilitates measuring the local gravity successfully. This FBG-based all-fiber single-sideband-modulated Raman light source, proposed for the first time and characterized as robust, compact and low-priced, is practical and potential for field applications of portable atom interferometry.

Agile offset frequency locking for single-frequency fiber lasers.

Single frequency fiber lasers (SFFLs) have seen increasing applications in state-of-the-art quantum technologies, which usually require precise and stable offset frequency locking (OFL). However, limited by the piezoelectric transducer bandwidth in SFFLs and the loop bandwidth of the OFL, the large-gap jumping between two locked offset frequencies will take an undesirable amount of time. In order to diminish that consuming time, we developed an agile offset frequency locking system based on a hybrid loop of a feed-forward path and a feedback path. In accordance with the experimental demonstration, we characterized the performances of the offset frequency locking system, as frequency-locking stability with an Allan deviation of 3.2 × 10-14 at 1 s averaging time and jumping agility with a duration of 0.6 ms at 1.3 GHz frequency gap, which is a factor of 60 faster than that without the feed-forward path. This mechanism can find direct applications in existing quantum metrology experiments with SFFLs where high-speed frequency jumping or sweeping is needed.

In situ probing and stabilizing the power ratio of electro-optic-modulated laser pairs based on VIPA etalon for quantum sensing.

Monitoring and stabilizing the power ratio of laser pairs is significant for high-precision atom interferometers, especially as the compact electro-optic-modulated all-fiber laser system prevails. In this Letter, we demonstrate a novel, to the best of our knowledge, method to in situ probe the relative power of laser pairs and to stabilize the power ratio of two Raman lasers using a high-dispersion virtually imaged phased array (VIPA) etalon. Sub-microsecond resolution on probing laser power transformation during the atom interferometer sequence is achieved and the power ratio of two Raman lasers (PRTR) is tightly locked with high bandwidth despite environmental disturbances, showing an Allan deviation of 4.39 × 10-5 at 1000 s averaging time. This method provides a novel way to stabilize the PRTR and diagnose multi-frequency laser systems for atom interferometers, and it could find potential applications in broad quantum sensing scenarios.

HuR Promotes the Progression of Gastric Cancer through Mediating CDC5L Expression.

Methods: We performed qRT-PCR, cell cycle assay, cell migration, and mouse transplantation model analysis in our experiments. It has been clarified that HuR and microRNAs (miRNAs) have important interplays in the regulation of tumor progression. Results: This study found microRNA-133b (miR-133b), as a HuR-sponged miRNA in GC cells. Downregulation of HuR can promote the expression of miR-133b and further affect the downstream cyclin CDC5L. The expressions of miR-133b were slightly lower in GC tissues than adjacent normal tissues. Conclusion: Our studies suggest that HuR and miR-133b are involved in the development and pathological process of GC cells.

Planar diffractive grating for magneto-optical trap application: fabrication and testing.

The design, fabrication, and demonstration of a planar two-dimensional-crossed reflective diffractive grating are proposed to construct a novel optical configuration, to the best of our knowledge, potentially applied for atom cooling and trapping in a magneto-optical trap. Based on the proposed single-beam single-exposure scheme by means of an orthogonal two-axis Lloyd's mirrors interferometer, we rapidly patterned a ∼1µm period grating capable of providing a uniform intensity of the diffracted beams. The key structural parameters of the grating including the array square hole's width and depth were determined, aiming at providing a high energy of the diffracted beams to perform the atom cooling and trapping. To guarantee the diffracted beams to be overlapped possibly, we adopted a polarized beam splitter to guide the optical path of the incident and zero-order diffracted beams. Therefore, one zero-order diffracted beam with a retroreflected mode and four first-order diffracted beams with appropriate optical path constructed a three-dimensional optical configuration of three orthogonal pairs of counterpropagating beams. Finally, three pairs of the counterpropagating cooling laser beams with 9 mm diameter and >10% diffraction efficiencies were achieved, and the circular polarization chirality, purity, and compensation of the desired diffracted beams are further evaluated, which preliminarily validated a high applicability for the magneto-optical trap system.

An Investigation on Substitution of Ag Atoms for Al or Ti Atoms in the Ti2AlC MAX Phase Ceramic Based on First-Principles Calculations.

The present work introduced first-principles calculation to explore the substitution behavior of Ag atoms for Al or Ti atoms in the Ti2AlC MAX phase ceramic. The effect of Ag substitution on supercell parameter, bonding characteristic, and stability of the Ti2AlC was investigated. The results show that for the substitution of Ag for Al, the Al-Ti bond was replaced by a weaker Ti-Ag bond, decreasing the stability of the Ti2AlC. However, the electrical conductivity of the Ti2AlC was enhanced after the substitution because of the contribution of Ag 4d orbital electrons toward the density of states (DOS) at the Fermi level coupled with the filling of Ti d orbital electrons. For the substitution of Ag for Ti, new bonds, such as Ag-Al bond, Ag-C bond, Al-Al bond, Ti-Ti anti-bond, and C-C anti-bond were generated in the Ti2AlC. The Ti-Ti anti-bond was strengthened as well as the number of C-C anti-bond was increased with increasing the substitution ratio of Ag for Ti. Similar to the substitution of Ag for Al, the stability of the Ti2AlC also decreased because the original Al-Ti bond became weaker as well as the Ti-Ti and C-C anti-bonds were generated during the substitution of Ag for Ti. Comparing with the loss of Ti d orbital electrons, Ag 4d orbits contributed more electrons to the DOS at the Fermi level, improving the electrical conductivity of the Ti2AlC after substitution. Based on the calculation, the substitution limit of Ag for Al or Ti was determined. At last, the substitution behavior of Ag for Al or Ti was compared to discriminate that Ag atoms would tend to preferentially substitute for Ti atoms in Ti2AlC. The current work provides a new perspective to understand intrinsic structural characteristic and lattice stability of the Ti2AlC MAX phase ceramic.

A simple method to generate arbitrary laser shapes for stimulated Raman adiabatic passage.

Stimulated Raman adiabatic passage (STIRAP) is an effective technique to transfer state coherently with the features of both high fidelity and robustness in the field of quantum information and quantum precise measurement. In this note, we present a simple method to generate arbitrary laser shapes for STIRAP by controlling the modulation depth of the electro-optic modulator (EOM) and the diffraction efficiency of the acoustic-optic modulator (AOM) simultaneously. The EOM and AOM are used to control the power ratio between the two Raman lasers (pumping laser and Stokes laser) and the total power, respectively. Compared with the traditional method by combining two Raman lasers separated in space, this method has the advantage of simple structure and insensitivity to the environment disturbance, which would degrade the relative phase noise between two Raman lasers.

Measuring the phase noise of Raman lasers with an atom-based method.

Phase noise of Raman lasers is a major source of noise for a Raman-type cold atom interferometer, which is traditionally measured using the signal source analyzer. We report here an atom-based method to measure the phase noise performance between two Raman lasers. By analyzing and calibrating the system noise sources, we can characterize the contribution of phase noise from the total deviation of the relative atom population at the middle of the interference fringe. Knowing the transfer function specified by the operation sequence of the interferometer, we can obtain the transfer function and power spectrum density of the phase noise term. By varying the time sequences of the interferometer, we can measure the white phase noise floor and the phase noise performance over a large range of Fourier frequencies from 1 to 100 000 Hz with a minor difference of 1 dB compared with results from the traditional method using a signal analyzer, which proves the validity of the atom-based method. Compared with the traditional measurement method, the atom-based method can have higher accuracy and have the ability of self-calibrating.

A new method for high-bandwidth servo control of the power ratio between two Raman beams for cold atom interferometer.

Light shift produced by the AC Stark effect is one of the major factors limiting the accuracy and long-term stability of a cold atom interferometer. The first order light shift can be canceled by fixing the power ratio of the Raman beams at a specified value. We report here a new method to stabilize the power ratio of the two Raman lasers with ∼100 kHz locking bandwidth, suppressing the effect of the first order light shift. We first mixed the two Raman lasers (at different optical frequencies) with a reference beam and then used two Schottky diode detectors to extract the corresponding beat note signals for each beam, which are much easier to be manipulated and processed as they are in the microwave band. The stability of the power ratio is improved by three orders of magnitude from 5.84 × 10-3 to 3.51 × 10-6 at 1 s averaging time and reaches 1.59 × 10-7 at 10 000 s integrating time when the servo loop is engaged. This method can be used in other precise quantum measurement based on the stimulated Raman transition and can be applied to compact inertial sensors.

Prognostic role of the systemic immune-inflammation index in brain metastases from lung adenocarcinoma with different EGFR mutations.

The prognostic value of the systemic immune-inflammation index (SII) has been shown in various types of cancers. We aimed to evaluate the predictive values in brain metastases from lung adenocarcinoma with status of EGFR mutations. We, retrospectively, examined 310 patients with brain metastases from lung adenocarcinoma with status of EGFR mutations. SII was calculated using P * N/L, where P, N, and L, respectively refer to peripheral blood lymphocyte, neutrophil, and platelet counts. The cut-off value of SII was assessed by area under the curve (AUC). The log-rank test and Cox proportional hazard model were used to confirm the impact of SII and other variables on survival. The SII value ≤ 1218.81 was associated with prolonged survival in patients with brain metastases from lung adenocarcinoma in both variable and multivariable analysis In patients with EGFR mutations, the SII had statistical effect on OS only in invariable test. While, for patients with wild-type EGFR, SII achieved statistically significant differences both in variable and multivariable analyses. SII is an independent prognostic factor in brain metastases from lung adenocarcinoma. SII may have varying prognostic effects on patients with and without EGFR mutations and is a promising variable for the future prognostic systems.

Nonlinear continuous fluctuation intensity financial dynamics and complexity behavior.

The exploration of return volatility dynamics is of great significance to evaluate investment risk, avoid stock market crisis, and purchase stock portfolio. In this paper, we propose a novel concept to characterize the fluctuation duration of stock markets, which is continuous fluctuation intensity (CFI). The CFI represents the duration for continuous increasing or decreasing return volatilities (or normalized absolute returns) above or below a previous day's value. Distinguished from previous studies, the CFI does not need to set a threshold in advance but to select the sequence of return volatilities that are continuously growing or falling in the series. So, the research on continuous fluctuation intensity is a new approach in return volatility study. For investigating the nonlinear properties of CFI, probability distribution, autocorrelation analysis, and scatterplot analysis are utilized for the empirical data from China and USA stock markets. Besides, fractional sample entropy and fuzzy entropy are employed to explore the complexity of CFI series. Then, some meaningful results of CFI series are acquired, which manifest that the study of the proposed concept is feasible and valuable. Moreover, we do the same investigations for return volatility series to explore the similarities and differences between CFI series and volatility series.

Real-Time and Meter-Scale Absolute Distance Measurement by Frequency-Comb-Referenced Multi-Wavelength Interferometry.

We report on a frequency-comb-referenced absolute interferometer which instantly measures long distance by integrating multi-wavelength interferometry with direct synthetic wavelength interferometry. The reported interferometer utilizes four different wavelengths, simultaneously calibrated to the frequency comb of a femtosecond laser, to implement subwavelength distance measurement, while direct synthetic wavelength interferometry is elaborately introduced by launching a fifth wavelength to extend a non-ambiguous range for meter-scale measurement. A linearity test performed comparatively with a He-Ne laser interferometer shows a residual error of less than 70.8 nm in peak-to-valley over a 3 m distance, and a 10 h distance comparison is demonstrated to gain fractional deviations of ~3 × 10-8 versus 3 m distance. Test results reveal that the presented absolute interferometer enables precise, stable, and long-term distance measurements and facilitates absolute positioning applications such as large-scale manufacturing and space missions.

New approach of financial volatility duration dynamics by stochastic finite-range interacting voter system.

We make an approach on investigating the fluctuation behaviors of financial volatility duration dynamics. A new concept of volatility two-component range intensity (VTRI) is developed, which constitutes the maximal variation range of volatility intensity and shortest passage time of duration, and can quantify the investment risk in financial markets. In an attempt to study and describe the nonlinear complex properties of VTRI, a random agent-based financial price model is developed by the finite-range interacting biased voter system. The autocorrelation behaviors and the power-law scaling behaviors of return time series and VTRI series are investigated. Then, the complexity of VTRI series of the real markets and the proposed model is analyzed by Fuzzy entropy (FuzzyEn) and Lempel-Ziv complexity. In this process, we apply the cross-Fuzzy entropy (C-FuzzyEn) to study the asynchrony of pairs of VTRI series. The empirical results reveal that the proposed model has the similar complex behaviors with the actual markets and indicate that the proposed stock VTRI series analysis and the financial model are meaningful and feasible to some extent.

Comb-referenced laser distance interferometer for industrial nanotechnology.

A prototype laser distance interferometer is demonstrated by incorporating the frequency comb of a femtosecond laser for mass-production of optoelectronic devices such as flat panel displays and solar cell devices. This comb-referenced interferometer uses four different wavelengths simultaneously to enable absolute distance measurement with the capability of comprehensive evaluation of the measurement stability and uncertainty. The measurement result reveals that the stability reaches 3.4 nm for a 3.8 m distance at 1.0 s averaging, which further reduces to 0.57 nm at 100 s averaging with a fractional stability of 1.5 × 10(-10). The uncertainty is estimated to be in a 10(-8) level when distance is measured in air due to the inevitable ambiguity in estimating the refractive index, but it can be enhanced to a 10(-10) level in vacuum.

Absolute positioning by multi-wavelength interferometry referenced to the frequency comb of a femtosecond laser.

A multi-wavelength interferometer utilizing the frequency comb of a femtosecond laser as the wavelength ruler is tested for its capability of ultra-precision positioning for machine axis control. The interferometer uses four different wavelengths phase-locked to the frequency comb and then determines the absolute position through a multi-channel scheme of detecting interference phases in parallel so as to enable fast, precise and stable measurements continuously over a few meters of axis-travel. Test results show that the proposed interferometer proves itself as a potential candidate of absolute-type position transducer needed for next-generation ultra-precision machine axis control, demonstrating linear errors of less than 61.9 nm in peak-to-valley over a 1-meter travel with an update rate of 100 Hz when compared to an incremental-type He-Ne laser interferometer.

Rapid detection of Akabane virus by a novel reverse transcription loop-mediated isothermal amplification assay (RT-LAMP).

BACKGROUND: Akabane disease, caused by Akabane virus, is an insect-transmitted disease of ruminants that is primarily characterized by fetal damage. METHODS AND RESULTS: In this study, a novel reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for rapid detection of Akabane virus was successfully developed. The primers were designed to target the highly conserved fragment of nucleoprotein from the Akabane virus. The results indicate that the assay is highly specific and sensitive with a detection limit of 5.0 TCID50/mL within a 60-min incubation time. A total of 126 abortive samples collected from Xinjiang province were detected by the established RT-LAMP. The results of RT-LAMP assay showed 96.8% agreement with the semi-nested RT-PCR. CONCLUSION: This study is to first to develop a rapid, sensitive, and accurate method for the detection of Akabane virus, which may be used to screen clinical samples in developing countries or regions.

[Efficacy of permanent interstitial implantation of 125I seeds for solitary brain metastasis from non-small cell lung carcinoma].

BACKGROUND & OBJECTIVE: Some studies have already showed that whole brain irradiation (WBI) could cause radiation brain damage. It is necessary to explore a novel treatment modality to replace whole brain irradiation without influencing the therapeutic efficacy. The purpose of this study was to assess the therapeutic efficacy and radiation brain damage of permanent interstitial implantation of 125I seeds following tumor resection for solitary brain metastasis from non-small cell lung carcinoma (NSCLC). METHODS: Sixty-seven patients with solitary brain metastasis from non-small cell lung carcinoma were randomly assigned into two groups: Thirty-two cases(47.8%) were treated with resection and permanent interstitial implantation of 125I seeds(I), and 35(52.2%) received whole brain irradiation and local-small-field radiation (C). All patients were biopsy-verified non-small cell lung carcinoma, including 42 squamous cell carcinomas and 25 adenocarcinomas. They all were solitary brain metastasis from non-small cell lung carcinoma diagnosed by CT or MRI. After resection of solitary brain metastasis, different numbers of 125I seeds were implanted according to some parameters in group I. In group C, 35 patients received whole brain irradiation to a total dose of 30-39 Gy/3-4 weeks, 2-3 Gy/fraction, 5 fractions/week followed by a boost of 15-25 Gy/2-3 weeks through local-small fields. RESULTS: The local control rate, the recurrent rate, and the median recurrent time were 96.9%, 15.6%, and 9 months in group I, and 82.9%, 17.1%, and 7 months in group C, respectively. The differences were no significant (P > 0.05). The median survival time, the 1-year survival rate, and the 1-year mortalities were 12 months, 40.6%, and 28.1% in group I, and 9 months, 31.4%, and 37.1% in group C, respectively. The differences were significant(P < 0.05). Acute irradiation response and radiation brain damage were markedly milder in group I than in group C. CONCLUSIONS: The results from this study show that resection and permanent interstitial implantation of 125I seeds for solitary brain metastasis from non-small cell lung carcinoma can not only improve the survival rates and decrease the mortalities, but also reduce radiation brain damage to improve the life quality. It is a good and effective modality, especially for younger patients. However, further study for long-term effect is needed.