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The combination of high-order modulation formats and linewidth-tolerant carrier phase estimation (CPE) can effectively improve spectrum efficiency and relax the limitation of laser linewidth. This paper presents a simple two-stage CPE algorithm for polarization-multiplexed (PM) 32-quadrature amplitude modulation (32-QAM) coherent optical communication systems. The algorithm uses an enhanced QPSK partitioning algorithm combined with a simplified 4th power CPE method for coarse estimation in the initial stage and maximum likelihood (ML) detection in the subsequent fine stage. The CPE algorithm significantly increases the number of symbols used in the first stage of coarse estimation. This results in a significant increase in the stability and reliability of the phase estimation, and the CPE algorithm significantly reduces the computational complexity. The optimal parameters, phase estimation performance, and system performance of the algorithm were investigated by building a 22 Gbaud PM 32-QAM coherent system simulation platform and a 5 Gbaud PM 32-QAM coherent system experimental platform. The results show that the proposed two-stage CPE algorithm has a stronger linewidth tolerance difference than the conventional QPSK, and the two-stage CPE algorithm with an optimal block length of 105 performs comparable to blind phase search (BPS). The optical signal noise Ratio (OSNR) value is 21.2 dB and the bit error rate (BER) is 1.8 × 10−3 for the optimal block length of 105. The receiving-end DSP unit with a flexible scheme and good communication performance will have potential applications in adaptive elastic optical networks.

In this paper, a filterless 32-tupling millimeter wave generation scheme based on eight MZMs is proposed. The system has an upper and lower parallel two-branch structure. The upper branch consists of two subsystems Sub-A and Sub-B in cascade, each subsystem contains four MZMs, and the MZMs are all operating at maximum transfer point (MATP). Sub-A mainly generates ±8th order optical sideband signal as the incident light signal of Sub-B. After modulation of Sub−B, the output signal is mainly ±16th order optical sideband signal containing the central optical carrier component. The optical attenuator (OATT) and optical phase shifter (OPS) of the lower branch are used to regulate the phase and amplitude of the optical carrier. The upper and lower branches are coupled, and the central optical carrier component is superimposed and cancelled so only the ±16th order optical sideband signal is retained. Finally, the 32-tupling frequency millimeter is generated by the photodiode (PD) receiver after photoelectric detection which receives and generates a 32-tupling frequency millimeter wave signal. The simulation results show that the 160 GHz millimeter wave signal can be obtained by driving the MZM with a 5 GHz RF signal, and the optical sideband suppression ratio (OSSR) and the RF sideband suppression ratio (RFSSR) are 52.6 dB and 44.75 dB, respectively. Theoretical analysis and simulation experiments are carried out for the proposed scheme which proves the feasibility of the scheme.

In this paper, we propose a camera projection approach to enhance the physical layer security of coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems. The data are converted to the new location by the camera projection module in the encryption system, where the 5D hyperchaotic system provides the keys for the camera projection module. The simulated 16QAM CO-OFDM security system over 80 km SSMF is shown to provide a key space of about 9 × 1090 through the five-dimensional (5D) hyperchaotic system, making it impossible for eavesdroppers to obtain valid information, and the peak-to-average power ratio (PAPR) is reduced by about 0.8 dB.

Twisted 2D materials have recently emerged as a controllable quantum simulator platform. Here, the authors apply the same approach to tune the edge states of zigzag graphene nanoribbons, showing a unique degree of freedom represented by the lateral stacking offset of the 1D nanostructures.

In this work, we employ two Mach-Zehnder modulators (MZM) to achieve a novel six kinds of reconfigurable optical logic gate in millimeter wave over fiber, in which one MZM is used to generate millimeter wave (mm-wave) signal and the other is used to attain optical logic gate. By adjusting the direct current (DC) bias voltage of the first MZM, a frequency doubling mm-wave signal can be obtained and no filter is needed. By controlling the radio frequency (RF) drive voltage and DC bias voltage of the second MZM, the phase of between upper and lower arms can be converted. By adjusting the phase of the first channel RF signal to $(\pi /2,0)$ , setting the phase of the second channel RF signal to $(0,\pi /2)$ and controlling the bias voltage to let the phase of the upper and lower to be $\pi /2$ and $\pi /4$ , respectively, OR logic gate can be obtained. To obtain AND, NOR, NAND, XOR and NXOR logic gate, we just need to get proper phase by adjusting the RF drive voltage and DC bias voltage of the second MZM. According to the simulation, the millimeter wave signal with a frequency of 50 GHz can be obtained, which has completed the logic operation.

The addendum and root of involute gear are modified，and the modified gear and unmodified gear are placed on the contact fatigue tester for comparative test. The variation of micro pitting corrosion on the tooth surface is reflected by measuring the profile fluctuation deviation and the tooth surface morphology. The experimental results show that the size and area of micropitting corrosion of the modified gear are much smaller than those of the unmodified gear under the same number of cycles，the micropitting propagation rate of the modified gear is also much lower than that of the unmodified gear. When the gear fatigue failure occurs，the number of cycles of the profile modification gear is much higher than that of the unmodified gear. It can be concluded that the profile modification greatly improves the anti micropitting ability and contact fatigue property of the gear.

The ATP consumption in heart is very intensive to support muscle contraction and relaxation. Mitochondrion is the power plant of the cell. Mitochondrial dysfunction has long been believed as the primary mechanism responsible for the inability of energy generation and utilization in heart failure. In addition, emerging evidence has demonstrated that mitochondrial dysfunction also contributes to calcium dysregulation, oxidative stress, proteotoxic insults and cardiomyocyte death. These elements interact with each other to form a vicious circle in failing heart. The role of mitochondrial dysfunction in the pathogenesis of heart failure has attracted increasing attention. The complex signaling of mitochondrial quality control provides multiple targets for maintaining mitochondrial function. Design of therapeutic strategies targeting mitochondrial dysfunction holds promise for the prevention and treatment of heart failure.

Objective With the rapid development of the Chinese economy, Xiaoshan District, Zhejiang Province has experienced urbanisation, population ageing and significant lifestyle changes, so diabetes mellitus (DM) has attracted more attention. This study aimed to evaluate the prevalence of DM and its risk factors among individuals aged 18 years and above in the district.Study design and methods A community-based cross-sectional study was carried out in Xiaoshan, China from 1 March to 31 August 2018. A multistage sampling method was used. Sociodemographic and behavioural characteristics were collected using a combination of centralised surveys and household surveys. Anthropometric parameters were measured with standardised techniques and calibrated equipment. Venous blood samples were obtained after at least 8 hours of fasting to determine the level of fasting blood glucose (FBG) and blood lipids. A standard 2-hour 75 g oral glucose tolerance test was also given if 6.1 mmol/L≤FBG

The unphosphorized and phosphatized spur gears produced in the same batch are divided into three groups，the unphosphorized gear group， the single phosphated gear group and the double phosphated gear group， the scuffing performance test is carried out in groups on the gear contact fatigue tester. At the same time， the helix curve of the test gears detected by the gear measuring center D80 is used to accurately calculate the gluing area and the depth of the gluing groove mark. The results show that， under the same operating conditions， the loading torque of the phosphated gear is much greater than that of the unphosphorized gear， and the operating time of the phosphated gear is much more than that of the unphosphorized gear. It is concluded that， phosphating can significantly improve the anti scuffing performance of gears.

A quantum noise stream cipher (QNSC) is a physical layer encryption technology based on quantum noise. Bit error rate loopback measurement (BER-LM) is a method to measure the BER of a loopback channel and extract channel characteristics. Then, channel characteristics can be extracted, and consensus keys can be obtained through negotiation. In previous studies, encryption and key distribution were implemented in independent channels. In this paper, we propose a scheme that combines these two technologies in a single fiber channel to achieve encrypted transmission and key distribution. We verified a 20 Gbps QPSK coherent optical transmission system with a PSK/QNSC scheme. The results show that by reasonably setting the negotiation bit position, the consensus key could be obtained through negotiation, and the requirements of transmission performance could be met. When the negotiation bit position was set to seven, the Q-factor of the system was nine, which met the error-free condition of the 7% forward error correction (FEC) limit.

In this paper, a universally composable 1-out-of-N oblivious transfer protocol with low communication is built. This protocol obtained full simulation security based on the modulo learning with rounding (Mod-LWR) assumption. It can achieve universally composable security in the random oracle machine (ROM) model by combining random OT based on the key exchange protocol with the authentication encryption algorithm. It can be proven to resist static adversary attacks by simulating all corruption cases. Based on computer simulation and detailed mathematical derivation, this protocol was practicable and had better efficiency and lower communication.

Background: Dilated cardiomyopathy (DCM) is a major cause of heart failure worldwide. The Z-line protein Cypher/Z-band alternatively spliced PDZ-motif protein (ZASP) is closely associated with DCM, both clinically and in animal models. Our earlier work revealed Cypher/ZASP as a PKA-anchoring protein (AKAP) that tethers PKA to phosphorylate target substrates. However, the downstream PKA effectors regulated by AKAP Cypher/ZASP and their relevance to DCM remain largely unknown.Methods and Results: For the identification of candidate PKA substrates, global quantitative phosphoproteomics was performed on cardiac tissue from wild-type and Cypher-knockout mice with PKA activation. A total of 216 phosphopeptides were differentially expressed in the Cypher-knockout mice; 31 phosphorylation sites were selected as candidates using the PKA consensus motifs. Bioinformatic analysis indicated that differentially expressed proteins were enriched mostly in cell adhesion and mRNA processing. Furthermore, the phosphorylation of β-catenin Ser675 was verified to be facilitated by Cypher. This phosphorylation promoted the transcriptional activity of β-catenin, and also the proliferative capacity of cardiomyocytes. Immunofluorescence staining demonstrated that Cypher colocalised with β-catenin in the intercalated discs (ICD) and altered the cytoplasmic distribution of β-catenin. Moreover, the phosphorylation of two other PKA substrates, vimentin Ser72 and troponin I Ser23/24, was suppressed by Cypher deletion.Conclusions: Cypher/ZASP plays an essential role in β-catenin activation via Ser675 phosphorylation, which modulates cardiomyocyte proliferation. Additionally, Cypher/ZASP regulates other PKA effectors, such as vimentin Ser72 and troponin I Ser23/24. These findings establish the AKAP Cypher/ZASP as a signalling hub in the progression of DCM.

This paper proposes a novel key distribution method based on the masking effect of fiber channel noise in a power transmission system. The two physical layer signal processing technologies used in this solution are frame synchronization and resampling. The random data sent and received is digitally processed by these two techniques. An experimental platform is built, and the key performance is assessed by analyzing the measured bit error rate (BER) dynamic curve, setting different decision thresholds and the amplitude of the state basis. Experimental results show that the key distribution rate can reach 10 kbit/s with a key consistency rate of 98%. This is of great significance to the development of safe optical communication technology in power transmission systems. In the power communication system, a large number of optical fiber communication devices are used. The key distribution method proposed in this paper can effectively improve the security of optical fiber communication, which is of great significance.

In angiosperms, anther development comprises of various complex and interrelated biological processes, critically needed for pollen viability. The transitory callose layer serves to separate the meiocytes. It helps in primexine formation, while the timely degradation of tapetal cells is essential for the timely callose wall dissolution and pollen wall formation by providing nutrients for pollen growth. In rice, many genes have been reported and functionally characterized that are involved in callose regulation and pollen wall patterning, including timely programmed cell death (PCD) of the tapetum, but the mechanism of pollen development largely remains ambiguous. We identified and functionally characterized a rice mutant dcet1, having a complete male-sterile phenotype caused by defects in anther callose wall, exine patterning, and tapetal PCD. DCET1 belongs to the RNA recognition motif (RRM)-containing family also called as the ribonucleoprotein (RNP) domain or RNA-binding domain (RBD) protein, having single-nucleotide polymorphism (SNP) substitution from G (threonine-192) to A (isoleucine-192) located at the fifth exon of LOC_Os08g02330, was responsible for the male sterile phenotype in mutant dcet1. Our cytological analysis suggested that DCET1 regulates callose biosynthesis and degradation, pollen exine formation by affecting exine wall patterning, including abnormal nexine, collapsed bacula, and irregular tectum, and timely PCD by delaying the tapetal cell degeneration. As a result, the microspore of dcet1 was swollen and abnormally bursted and even collapsed within the anther locule characterizing complete male sterility. GUS and qRT-PCR analysis indicated that DCET1 is specifically expressed in the anther till the developmental stage 9, consistent with the observed phenotype. The characterization of DCET1 in callose regulation, pollen wall patterning, and tapetal cell PCD strengthens our knowledge for knowing the regulatory pathways involved in rice male reproductive development and has future prospects in hybrid rice breeding.

The atomically clean surface of the iron-based superconductor FeTe_{0.55}Se_{0.45} is investigated by low-temperature scanning tunneling microscope (STM) with different tip apex states. We show that the scattering channel between the Γ and X/Y points of the sample's Brillouin zone can be visualized clearly by a supersharp STM tip. Furthermore, by manipulating a single Fe atom onto the tip apex, signatures of the orbital nature of the subsurface Fe layer of FeTe_{0.55}Se_{0.45} can be identified. By preparing a charged tip state, the intrinsic spatial inhomogeneity of the chemical potential of FeTe_{0.55}Se_{0.45} can be revealed. As a result, three different types of vortex bound states originating from locally varying topological properties of the FeTe_{0.55}Se_{0.45} surface are observed by scanning tunneling spectroscopy.

Molecular electronics or spintronics relies on manipulating the electronic transport through microscopic molecule structures. Here the authors demonstrate the selective electron pathway in single-molecule device by magnetic field which enables a tunable anisotropic magnetoresistance up to 93%.

The hirth coupling is widely used in the centrifugal air compressor unit due to its characteristic of high torque capacity，self centering and so on. A feasible method for the measuring of pitch plane is illustrated and the offline detection for the accuracy of hirth coupling is carried out by using gear tester， some reference for the measurement of relevant parts and the offline detection are provided.

In this paper, we propose a new frequency quadrupling scheme to generate a quadrature phase shift keying (QPSK) modulated vector millimeter-wave signal, in which an optical filter is not necessary. To eliminate constellation overlapping of the generated vector millimeter-wave signal caused by phase multiplication in the process of frequency multiplication, a precoding assisted technique is adopted. The principle and feasibility of the proposed scheme is deduced by a detailed mathematical formula. Simulations are carried out to generate 40 GHz QPSK modulated vector millimeter-wave signals using a 10 GHz radio frequency source and the BER performance is analyzed in detail. The results show that BER of the generated 5/10-Gbaud vector millimeter-wave signal is below 3.8×10-3, when the input optical power for into photo-detector is higher than −20.67 dBm.

We propose and verify a simple precoding-less scheme to generate quadrature phase shift keying (QPSK) modulated vector millimeter-wave signal based on a single phase modulator (PM). The electrical vector data is first up-converted to achieve a 12 GHz radio frequency (RF) vector signal, then the RF vector signal is added with the other unmodulated RF source at 18 GHz, of which the generations are enabled by a digital signal processing (DSP). Next, the coupled RF source drive a PM to generate multi-frequency optical sidebands. A wavelength selective switch is adopted to pick out two optical sidebands at different frequencies which will beat frequency in the photo-detector (PD). In this scheme, we set up a simulation platform to generate 48 GHz QPSK modulated vector millimeter-wave signals and analyzed the performance. The results show when the input power for the generated 1-Gbaud/s vector millimeter-wave into PD is not less than −18 dBm, the bit-error ratio can be below 3.8 × 10−3, which demonstrate that the generated vector millimeter-wave signal enabled by our proposed scheme can work well.

As the most prevalent element on our planet, carbon manifests a wide variety of allotropic phases, significantly contributing to its complex physical properties. Recently, several carbon allotropes have been reported to possess abundant topological phases in theory and experiment. This work focuses on a sp3 carbon allotrope, Z-ACA allotrope, which consists of 5-6-7-type Z-ACA carbon rings. This allotrope has been reported previously as a superhard material comparable to diamond. In this study, we report that it is a candidate for both an obstructed atomic insulator and a real Chern insulator. It is worth mentioning that Z-ACA exhibits an unconventional bulk-boundary correspondence due to its hinge boundary state manifestation. Our current research indicates that Z-ACA is a suitable carbon phase platform for studying the real topology and second-order bulk-boundary correspondence. [ABSTRACT FROM AUTHOR]

In work, a new method of optical microwave signal generation with frequency 18-tupling using three parallel polarization modulators (PolMs) was proposed, in which the PolM is integrated through a polarization beam splitter, two phase modulators, an electrical phase shifter, and a polarization beam coupler. To generate a frequency 18-tupling millimeter-wave (mm-wave) signal, the polarization controller must first be employed to bring out linearly polarized light. Next, the linearly polarized light is faded into three PolMs to be modulated by a radio frequency signal, which can achieve multi-frequency optical sidebands. Last, controlling a polarizer to cancel unwanted optical sidebands to obtain ±9th optical sidebands is used to generate an 18-tupling mmwave signal. We have conducted detailed mathematical formula derivation and computer simulation for the scheme. The results show that the scheme can be experimentally realized and accurate enough with the performance of the signal: the optical sideband suppression ratio can reach 48.02 dB, and the radio frequency spurious suppression ratio can reach 42.25 dB, almost equal to the theoretical model. [ABSTRACT FROM AUTHOR]

The existing frequency bands, such as the C-band and L-band, are becoming increasingly crowded and cannot meet the growing demand for high-speed data rate services. To overcome spectrum congestion, meet future business needs, and overcome the bottlenecks of traditional electronic methods, we have modified an approach for generating W-band mm-wave signals with octupling frequency without the need for an optical filter. One integrated modulator consisting of two push-pull Mach-Zehnder modulators (MZM) in series is employed to achieve W-band signal generation. The octupling frequency signal generation depends on ±4th optical sidebands to beat frequency in the photodetector. For capturing ±4th optical sidebands, the bias point of the two push-pull MZMs needs work at the peak point, and the modulation index of the two MZMs should be simultaneously set to 2.4. We have conducted detailed mathematical derivation and computer simulation for the scheme, demonstrating its correctness. The results show that the optical sideband suppression ratio is not less than 45.73 dB, and the RF sideband suppression ratio can reach 37.64 dB. [ABSTRACT FROM AUTHOR]

The growth, atomic structure, and electronic property of trilayer graphene (TLG) on Ru(0001) were studied by low temperature scanning tunneling microscopy and spectroscopy in combined with tight-binding approximation (TBA) calculations. TLG on Ru(0001) shows a flat surface with a hexagonal lattice due to the screening effect of the bottom two layers and the AB-stacking in the top two layers. The coexistence of AA- and AB-stacking in the bottom two layers leads to three different stacking orders of TLG, namely, ABA-, ABC-, and ABB-stacking. STS measurements combined with TBA calculations reveal that the density of states of TLG with ABC- and ABB-stacking is characterized by one and two sharp peaks near to the Fermi level, respectively, in contrast to the V-shaped feature of TLG with ABA-stacking. Our work demonstrates that TLG on Ru(0001) might be an ideal platform for exploring stacking-dependent electronic properties of graphene. [ABSTRACT FROM AUTHOR]

The threats caused by the environmental crisis and energy shortages have been paid close attention in recent years. For its obvious advantage of reducing vehicle emissions effectively and efficiently, hydrogen is expected to be greatly used as a kind of new energy. Besides, it can be an alternative fuel to petroleum fuel of internal combustion engine. Unfortunately, this new energy does give rise to some undesirable combustion problems, such as backfire, pre-ignition, knocking and rapid rate of pressure rise. Lots of experiments have shown that optimizing the advanced ignition angle of hydrogen-fueled engine is one of the main methods to solve these problems. In this paper, a new kind of neural network model is proposed to predict and control the advanced ignition angle of hydrogen-fueled engine. More promising results have been obtained when the highly efficacious tool of Ant Colony Optimization (ACO) was utilized as the method to optimize the weights and thresholds of the neural networks. Compared with the basic BP neural network, this proposed model can predict the desired advanced ignition angle in various situations more accurately and has the advantages of higher convergence rate and fitting degree. [ABSTRACT FROM AUTHOR]

As quasi-one-dimensional (1D) structures with characteristic widths of nanometer scale, graphene wrinkles (GWs) have been widely observed in graphene grown by chemical vapor deposition. Similar to conventional 1D graphene-based nanostructures, e.g., carbon nanotubes and graphene nanoribbons, 1D electron confinement has been observed in the GWs. However, it remains an open question whether the GWs have effective edges and exhibit corresponding edge states. Here, we report on the edge states of the GWs in single-layer graphene grown on Ni(111) by means of low temperature scanning tunneling microscopy and spectroscopy. We show that the GWs are decoupled from the substrate, while the surrounding planar graphene are strongly coupled with the substrate. The different graphene-substrate coupling leads to effective edges and 1D character of the GWs. The chiral edges of the GWs give rise to pronounced edge states around the Fermi level in the density of states. [ABSTRACT FROM AUTHOR]

Yu-Shiba-Rusinov (YSR) bound states appear when a magnetic atom interacts with a superconductor. Here, we report on spin-resolved spectroscopic studies of YSR states related with Fe atoms deposited on the surface of the topological superconductor FeTe0.55Se0.45 using a spin-polarized scanning tunneling microscope. We clearly identify the spin signature of pairs of YSR bound states at finite energies within the superconducting gap having opposite spin polarization as theoretically predicted. In addition, we also observe zero-energy bound states for some of the adsorbed Fe atoms. In this case, a spin signature is found to be absent indicating the absence of Majorana bound states associated with Fe adatoms on FeTe0.55Se0.45. [ABSTRACT FROM AUTHOR]