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Grain size is one of the crucial factors determining grain yield. However, the genetic and molecular mechanisms of florigen repression complexes (FRCs) underlying grain size in rice (Oryza sativa L.) have not been reported. Here, we report that the rice CENTRORADIALIS (CEN) family member OsCEN2 (also known as Rice TFL1/CEN homolog, RCN1), a phosphatidylethanolamine-binding protein (PEBP) family protein, negatively controls grain size in rice. Overexpression of OsCEN2 led to small grains, and knockout of OsCEN2 resulted in large, heavy grains. OsCEN2 influenced grain size by restricting cell expansion in the spikelet hull and seed filling. In in vivo and in vitro experiments, OsCEN2 physically interacted with a G-box factor 14-3-3 homolog, GF14f, which negatively regulates grain size. Bimolecular fluorescence complementation and yeast two-hybrid assays revealed that GF14f directly interacts with the basic leucine zipper (bZIP) transcription factor, OsFD2. Plants overexpressing OsFD2 produced smaller and lighter grains than wild-type plants. We found that OsFD2 also influences grain size by controlling cell expansion and division in the spikelet hull. Our results reveal the molecular mechanisms of the OsCEN2–GF14f–OsFD2 regulatory module in controlling grain size. Additionally, our study provides insight into the functions of the FRC in rice and suggests a strategy for improving seed size and weight.

Most plant pentatricopeptide repeat (PPR) proteins localize to and function inside plastids and mitochondria. However, the function of PPRs that only localize to the cytoplasm remains unknown. Here, we demonstrated that the rice (Oryza sativa) PPR protein CYTOPLASM-LOCALIZED PPR1 (OsCPPR1) contributes to pollen development and localizes to the cytoplasm. Knocking down OsCPPR1 led to abnormal plastid development in tapetal cells, prolonged tapetal programmed cell death (PCD) and tapetum degradation, and significantly reduced pollen fertility. Transcriptome analysis revealed that the transcript level of OsGOLDEN-LIKE1 (OsGLK1), which encodes a transcription factor that regulates plastid development and maintenance, was significantly higher in the OsCPPR1 knockdown plants compared to wild-type plants. We further determined that OsCPPR1 downregulates OsGLK1 transcription by directly binding to the single-stranded regions of OsGLK1 mRNAs. Overexpression of OsGLK1 resulted in abnormal tapetum and plastid development, similar to that seen in OsCPPR1 knockdown plants, and suppression of OsGLK1 partially restored pollen fertility in the OsCPPR1 knockdown plants. We therefore conclude that OsCPPR1 suppresses OsGLK1 in the regulation of plastid development and PCD in the tapetum. Our work revealed novel functions for a cytosolic PPR, demonstrating the diverse roles of PPRs in plants and identifying a new regulatory mechanism for regulating pollen development in rice.

Rice is one of the most important crops worldwide, whose yield is vital to human nutrition in the context of a rapidly growing world population. Plant architecture significantly affects grain yield, which is to a large extent determined by tiller angle and tiller number. Tiller angle is the angle between the primary tiller and the main culm. Its regulation is complex and is influenced by multiple environmental and genetic factors. This review provides an overview of the regulation of tiller angle in rice, with particular focus on the roles of the growth environment and method of cultivation; phytohormones such as auxin, gibberellins, and strigolactones; gravity; and genes related to the control of tiller angle. The major research foci and the outlook for research into the regulation of tiller angle in rice are discussed.

Single-layer phase screen is a classical, simple and accurate approach for simulating the optical field under turbulence, and it is generally used in free space optical communication (FSOC). However, conventional single-layer phase screen studies have rarely considered the pointing errors from FSOC, which prevents the theoretical results for mobile FSOC from being verified using simulated optical fields. This work establishes a simulation method for the single-layer phase screen with pointing errors. Statistics on simulated optical field with pointing errors indicated that the previous theoretical results for the long-term average irradiance and irradiance fluctuation probability density function (PDF) for mobile FSOC can be modified to better fit the simulation results. In addition, the received power fluctuation PDF, average bit-error-rate (BER), and the influence of non-zero mean pointing errors are investigated through the simulated optical field with pointing errors. The proposed simulation method provides a powerful approach for understanding and evaluating the comprehensive influences of atmospheric turbulence and pointing errors on the FSOC.

A FT/TFL1 subfamily gene, rice CENTRORADIALIS 2, also known as RCN1, regulates seed germination and increase salt tolerance via ABA-mediated pathway. The ABA synthesis and metabolism related genes were changed relative expression levels. Seed germination is a complex biological process that is affected by many factors. Although a number of germination-related genes have been reported, the molecular mechanism of germination regulation has not yet been fully elucidated. Here, we reported that the rice OsCEN2 gene can negatively regulate seed germination. The germination speed of OsCEN2-RNAi seeds was significantly faster while that of OsCEN2-overexpression (OE) seeds was slower than that of the wild type (WT). The results of qRT-PCR showed that the OsCEN2 expression was increased in the early stage of seed germination. Exogenous application of abscisic acid (ABA) on seeds and seedlings showed that OsCEN2-OE seeds and seedlings were highly sensitive to ABA during germination and post-germination growth, respectively. The determination of endogenous ABA content in seeds also showed that the ABA content of OsCEN2-RNAi seeds was lower, while that of OsCEN2-OE seeds was higher. Moreover, the transgenic plants changed salt tolerance because of the altered ABA level. In addition, differences were also observed in the expression of genes related to ABA synthesis and metabolism in the seeds of OsCEN2-transgenic lines. This study reveals that OsCEN2 regulates the germination speed by affecting the content of ABA during seed germination and provides a theoretical basis for research on rice direct seeding.

Flowers are the core reproductive organ of plants, and flowering is essential for cross-pollination. Diurnal flower-opening time is thus a key trait influencing reproductive isolation, hybrid breeding, and thermostability in plants. However, the molecular mechanisms controlling this trait remain unknown. Here, we report that rice Diurnal Flower Opening Time 1 (DFOT1) modulates pectin methylesterase (PME) activity to regulate pectin methylesterification levels of the lodicule cell walls, which affect lodicule swelling to control diurnal flower-opening time. DFOT1 is specifically expressed in the lodicules, and its expression gradually increases with the approach to flowering but decreases with flowering. Importantly, a knockout of DFOT1 showed earlier diurnal flower opening. We demonstrate that DFOT1 interacts directly with multiple PMEs to promote their activity. Knockout of PME40 also resulted in early diurnal flower opening, whereas overexpression of PME42 delayed diurnal flower opening. Lower PME activity was observed to be associated with higher levels of pectin methylesterification and the softening of cell walls in lodicules, which contribute to the absorption of water by lodicules and cause them to swell, thus promoting early diurnal flower opening. Higher PME activity had the opposite effect. Collectively, our work uncovers a molecular mechanism underlying the regulation of diurnal flower-opening time in rice, which would help reduce the costs of hybrid breeding and improve the heat tolerance of flowering plants by avoiding higher temperatures at anthesis.

Programmed cell death (PCD) plays crucial roles in plant development and defence response. Reactive oxygen species (ROS) are produced during normal plant growth, and high ROS concentrations can change the antioxidant status of cells, leading to spontaneous cell death. In addition, ROS function as signalling molecules to improve plant stress tolerance, and they induce PCD under different conditions. This review describes the mechanisms underlying plant PCD, the key functions of mitochondria and chloroplasts in PCD, and the relationship between mitochondria and chloroplasts during PCD. Additionally, the review discusses the factors that regulate PCD. Most importantly, in this review, we summarise the sites of production of ROS and discuss the roles of ROS that not only trigger multiple signalling pathways leading to PCD but also participate in the execution of PCD, highlighting the importance of ROS in PCD.

Challenges like occlusion, background clutter, illumination and scale variation make visual object tracking a tough problem in computer vision. Part-based tracking methods have been widely used to solve the partial occlusion issue, different from various holistic appearance model based trackers, it combines the local appearances of the target to build a robust global appearance. In this paper, we propose a novel object tracking method based on multi-part scheme and Bayesian framework, using the Kernelized Correlation Filter (KCF) as the base tracker. Additionally, two robust reliability metrics are proposed: the first one utilizes the similarity between the corresponding parts in consecutive frames to measure the reliability; while the second one measures the contribution that each part made for the global target object. Besides, adaptive updating strategy and scale estimation which employ the relationships among parts are proposed to deal with appearance modeling. Extensive experiments have been conducted on latest benchmark to demonstrate that our method outperforms state-of-the-art trackers.

Trehalose plays an important role in mediating stress responses in plants, and trehalose-6-phosphate synthases and trehalose-6-phosphate phosphatases are essential for trehalose biosynthesis. Here, we address the function of rice (Oryza sativa) OsTPP3. We analyzed the expression of OsTPP3 in different tissues and stress conditions, and generated OsTPP3-overexpressing rice plants. These plants showed a higher tolerance to simulated drought conditions (10% PEG treatment) than wild-type (WT) plants. Reverse-transcription quantitative PCR analysis indicated that transcript levels of genes related to stress responses and abscisic acid biosynthesis were significantly higher in the OsTPP3 overexpressors than in WT plants. These results highlight the importance of OsTPP3 in conferring drought tolerance in rice.

Significance Understanding the development of anthers, the male reproductive organs of plants, has key implications for crop yield. Epigenetic mechanisms modulate gene expression by altering modifications of DNA or histones and via noncoding RNAs. Many studies have examined anther development, but the involvement of epigenetic mechanisms remains to be explored. Here, we investigated the role of an ARGONAUTE (AGO) family protein, OsAGO2. We find that OsAGO2 epigenetically regulates anther development by modulating DNA methylation modifications in the Hexokinase (OsHXK) promoter region. OsHXK1, in turn, affects anther development by regulating the production of reactive oxygen and the initiation of cell death in key anther structures. Identification of this epigenetic regulatory mechanism has implications for the production of hybrid crop varieties., Proteins of the ARGONAUTE (AGO) family function in the epigenetic regulation of gene expression. Although the rice (Oryza sativa) genome encodes 19 predicted AGO proteins, few of their functions have thus far been characterized. Here, we show that the AGO protein OsAGO2 regulates anther development in rice. OsAGO2 was highly expressed in anthers. Knockdown of OsAGO2 led to the overaccumulation of reactive oxygen species (ROS) and abnormal anther development, causing premature initiation of tapetal programmed cell death (PCD) and pollen abortion. The expression level of Hexokinase 1 (OsHXK1) increased significantly, and the methylation levels of its promoter decreased, in plants with knocked-down OsAGO2 expression. Overexpression of OsHXK1 also resulted in the overaccumulation of ROS, premature initiation of PCD, and pollen abortion. Moreover, knockdown of OsHXK1 restored pollen fertility in OsAGO2 knockdown plants. Chromatin immunoprecipitation assays demonstrated that OsAGO2 binds directly to the OsHXK1 promoter region, suggesting that OsHXK1 is a target gene of OsAGO2. These results indicate that OsHXK1 controls the appropriate production of ROS and the proper timing of tapetal PCD and is directly regulated by OsAGO2 through epigenetic regulation.

Convenient and time-saving one-step strategies for detecting ultralow concentrations of protein biomarkers play key roles in rapid disease diagnosis. In this study, we report a one-step detection method based on a nanofibrous sensing platform via the combination of proximity-induced DNA strand displacement (PiDSD), catalytic hairpin assembly (CHA) amplification and thioflavin T (ThT) binding. The interface behaviors on the nanofibrous membrane were studied to promote interface reaction kinetics and thermodynamics. Thrombin was used as a model biomarker, and the nanofibrous sensing platform achieved a limit of detection as low as 1.0 pM, a wide linear range of 50 pM to 5 nM, excellent specificity and good long-term stability. Compared with previous one-step thrombin detection methods, our one-step detection method is label-free, convenient and much more sensitive; it has potential applications for protein detection in point-to-care testing (POCT) and early diagnosis.

To examine physiological responses of garlic to salinity, 17-day-old seedlings of eight soft-neck accessions were treated with 200 mM NaCl for seven days in a hydroponic system. Several morphological and physiological traits were measured at the end of the treatment, including shoot height, shoot fresh weight, shoot dry weight, root length, root fresh weight, root dry weight, photosynthesis rate, and concentrations of Na+ and K+ in leaves. The principal component analysis showed that shoot dry weight and K+/Na+ ratio contribute the most to salt tolerance among the garlic accessions. As a result, salt-tolerant and sensitive accessions were grouped based on these two parameters. Furthermore, to investigate the molecular mechanisms in garlic in response to salinity, the transcriptomes of leaves and roots between salt-tolerant and salt-sensitive garlic accessions were compared. Approximately 1.5 billion read pairs were obtained from 24 libraries generated from the leaves and roots of the salt-tolerant and salt-sensitive garlic accessions. A total of 47,509 genes were identified by mapping the cleaned reads to the garlic reference genome. Statistical analysis indicated that 1282 and 1068 genes were upregulated solely in the tolerant leaves and roots, whereas 1505 and 1203 genes were downregulated exclusively in the tolerant leaves and roots after NaCl treatment, respectively. Functional categorization of these genes revealed their involvement in a variety of biological processes. Several genes important for carotenoid biosynthesis, auxin signaling, and K+ transport were strongly altered in roots by NaCl treatment and could be candidate genes for garlic salt tolerance improvement.

Most pentatricopeptide repeat (PPR) proteins localize to plastids or mitochondria, where they participate in RNA metabolism and post-transcriptionally regulate organelle gene expression. However, whether PPR proteins regulate the expression of nucleus-encoded genes remains unclear. Here, we uncovered a function for the rice (Oryza. sativa L.) PPR protein OsPPR2-1 (Os02g0110400) in pollen development and showed that, in contrast to most other PPR proteins, OPPR2-1 resides in the cytoplasm. Downregulating OsPPR2-1 expression led to abnormal plastid development in tapetal cells, prolonged programmed cell death (PCD), prolonged tapetum degradation, and significantly reduced pollen fertility. Transcriptome analysis revealed that the expression of OsGOLDEN-LIKE 1 (OsGLK1), encoding a transcription factor that regulates plastid development and maintenance, was significantly higher in plants with downregulated OsPPR2-1 expression compared to the wild type. Moreover, OsPPR2-1 bound to the OsGLK1 mRNA in RNA immunoprecipitation and RNA-electrophoretic mobility shift assays. An in vitro cleavage assay showed that OsPPR2-1 could degrade the OsGLK1 mRNA. Notably, knockdown of OsGLK1 partially restored pollen fertility in OsPPR2-1-knockdown plants and OsGLK1-overexpressing plants showed abnormal tapetum and plastid development, similar to the OsPPR2-1-knockdown plants. Together, our findings demonstrate that OsPPR2-1 regulates OsGLK1 expression, thereby controlling plastid development and PCD in the tapetum.

Wireless optical communication technology can provide larger channel capacity for aircraft platforms which has great potentiality. In the application scenario of aircraft platform, the pointing error is inevitable. This study analyzes the fade probability of the link based on Hermite-Gaussian beam by using single-layer phase screen with pointing error simulation method and comparing with Gaussian beam. The higher order Hermite-Gaussian beam shows better link stability performance. Atmosphere turbulence has obvious effect on fade probability when the standard variance of pointing error is small, with the increase of standard variance of pointing error, the major influence factor for fade probability is pointing error rather than atmosphere turbulence.

An enzyme-free and label-free visual sensing strategy was developed for sensitively detecting thrombin using a plasmonic nanoplatform. Both the thrombin-triggered catalytic hairpin assembly (CHA) amplification reaction and G-quadruplex/hemin DNAzyme-controlled plasmonic signal readout were engineered on an electrospun nanofibrous membrane. Owing to its large specific surface area and porous structure, the nanofibrous membrane enhanced the loading capacity of B-H2 and the interface interaction efficiency. This plasmonic nanoplatform was used to perform the sensitive and naked-eye detection of thrombin as low as 1.0 pM in human serum samples. This visual strategy can discriminate thrombin from other co-existing proteins very well. Moreover, the visual sensing platform exhibited excellent reusability and long-term stability. The proposed enzyme-free and label-free plasmonic nanoplatform is low-cost, easy to operate and highly sensitive, and has potential applications in the point-of-care detection of protein biomarkers.

Rapid and low-cost diagnosis of multiple infectious diseases is of great significance especially in densely populated or resource-constrained settings. Herein, we developed a one-step fast and label-free imaging array for multiplexed detection of trace avian influenza virus (AIV) DNA biomarkers. By designing a series of specific and efficient catalytic hairpin assembly (CHA) amplification reactions and utilizing thioflavin T, a specific G-quadruplex fluorescence probe, three subtypes of AIV DNA biomarkers (H1N1, H7N9 and H5N1) were simultaneously and quickly detected within only 20 min, which just needed a small reagent volume of 50 μL and a smartphone instead of a spectrometer. With the combination of fluorescence imaging output and grey-level analysis, the array sensor can be on-site with the limit of detection of 136 pM, 141 pM and 129 pM for H1N1, H7N9 and H5N1, respectively. The imaging array also displayed good mismatch discrimination, excellent anti-interference, and real sample application. In view of its advantages of fast detection, low cost and multiplexed analysis, the imaging array is expected to have potential applications for early infectious disease diagnosis in resource-constrained settings.

Free space optical communication (FSOC) has shown significant potential in the small satellite’s bandwidth communication link. However, the performance of small satellite FSOC link decays greatly by pointing error. This study presents and simulating verifies that adopting flat-topped beam to replace conventional Gaussian beam can mitigate the impacts of pointing error on a small satellite FSOC link. In addition, a novel contribution to the literature has been made by deducing theoretical expressions for the link performance design of flat-topped beam-based small satellite FSOC. The next generation of small satellite FSOC link could adopt flat-topped beam.

Based on the vectorial Rayleigh diffraction integral, the analytical propagation expression of a nonparaxial vectorial vortex beam carrying orbital angular momentum (OAM), diffracted at a circular aperture, is presented. The effects of both f parameter and topological charge (m) on the nonparaxiality of apertured vectorial vortex beams are studied. Simulation results show that the topological charge of transverse field component m will shift to m-1, for that of longitudinal field component.

Background The NAC (NAM, AFAT, and CUC) transcription factors play critical roles in rice (Oryza sativa) development and stress regulation. Overexpressing a microRNA (miR164b)-resistant OsNAC2 mutant gene, which generates transcripts that cannot be targeted by miR164b, improves rice plant architecture and yield; however, the performance of these mOsNAC2-overexpressing lines, named ZUOErN3 and ZUOErN4, under abiotic stress conditions such as drought have not yet been fully characterized. Results In this study, we showed that the germination of ZUOErN3 and ZUOErN4 seeds was delayed in comparison with the wild-type (WT) seeds, although the final germination rates of all lines were over 95%. The quantification of the endogenous ABA levels revealed that the germinating mOsNAC2-overexpressing seeds had elevated ABA levels, which resulted in their slower germination. The mOsNAC2-overexpressing plants were significantly more drought tolerance than the WT plants, with the survival rate increasing from 11.2% in the WT to nearly 70% in ZUOErN3 and ZUOErN4 plants after a drought treatment. Salt (NaCl) tolerance was also increased in the ZUOErN3 and ZUOErN4 plants due to significantly increased ABA levels. A reverse transcription quantitative PCR (RT-qPCR) analysis showed a significant increase in the expression of the ABA biosynthesis genes OsNCED1 and OsNCED3 in the mOsNAC2-overexpressing lines, and the expression levels of the stress-responsive genes OsP5CS1, OsLEA3, and OsRab16 were significantly increased in these plants. Moreover, OsNAC2 directly interacted with the promoters of OsLEA3 and OsNCED3 in yeast one-hybrid assays. Conclusions Taken together, our results show that OsNAC2 plays a positive regulatory role in drought and salt tolerance in rice through ABA-mediated pathways.

Background ARGONAUTE 1 (AGO1) proteins can recruit small RNAs to regulate gene expression, involving several growth and development processes in Arabidopsis. Rice genome contains four AGO1 genes, OsAGO1a to OsAGO1d. However, the regulatory functions to rice growth and development of each AGO1 gene are still unknown. Results We obtained overexpression and RNAi transgenic lines of each OsAGO1 gene. However, only up- and down-regulation of OsAGO1b caused multiple abnormal phenotypic changes in rice, indicating that OsAGO1b is the key player in rice growth and organ development compared with other three OsAGO1s. qRT-PCR assays showed that OsAGO1b was almost unanimously expressed in leaves at different developmental stages, and strongly expressed in spikelets at S1 to S3 stages. OsAGO1b is a typical AGO protein, and co-localized in both the nucleus and cytoplasm simultaneously. Overexpression of OsAGO1b caused adaxially rolled leaves and a series of abnormal phenotypes, such as the reduced tiller number and plant height. Knockdown lines of OsAGO1b showed almost normal leaves, but the seed setting percentage was significantly reduced accompanied by the disturbed anther patterning and reduced pollen fertility. Further anatomical observation revealed that OsAGO1b overexpression plants showed the partially defective development of sclerenchymatous cells on the abaxial side of leaves. In situ hybridization showed OsAGO1b mRNA was uniformly accumulated in P1 to P3 primordia without polarity property, suggesting OsAGO1b did not regulate the adaxial-abaxial polarity development directly. The expression levels of several genes related to leaf polarity development and vascular bundle differentiation were observably changed. Notably, the accumulation of miR166 and TAS3-siRNA was decreased, and their targeted OSHBs and OsARFs were significantly up-regulated. The mRNA distribution patterns of OSHB3 and OsARF4 in leaves remained almost unchanged between ZH11 and OsAGO1b overexpression lines, but their expression levels were enhanced at the regions of vascular bundles and sclerenchymatous cell differentiation. Conclusions In summary, we demonstrated OsAGO1b is the leading player among four OsAGO1s in rice growth and development. We propose that OsAGO1b may regulate the abaxial sclerenchymatous cell differentiation by affecting the expression of OSHBs in rice. Electronic supplementary material The online version of this article (10.1186/s12284-019-0323-9) contains supplementary material, which is available to authorized users.

The radiation forces of focused partially coherent anomalous vortex (AV) beams on Rayleigh particles of different refractive indices are studied theoretically and numerically. The influences of the topological charge, the beam order and coherence length on the radiation force are also discussed. It is shown that the focused partially coherent AV beam can be used to trap high index of refraction particles at the focus and to trap low index of refraction particles in the vicinity of the focus. It is also found that the radiation force can be modulated by the topological charge, the beam order and the coherence length.

Additional file 1: Figure S1. Effects of ABA on rice seed germination. WT seeds were imbibed in water containing 2.5 μmol/L ABA at 25/23 °C (day/night). Seeds from mOsNAC2-overexpressing lines (ZUOErN3 and ZUOErN4) were imbibed in water only. Images were taken after germination for 3 d (a), 5 d (b), and 8 d (c). Figure S2. Effects of fluridone (FLU) on rice seed germination. WT seeds were imbibed in water at 25/23 °C (day/night). Seeds from OsNAC2 overexpression lines (ZUOErN3 and ZUOErN4) were imbibed in water containing 80 μmol/L FLU at 25/23 °C (day/night). The images were taken on day 2 after germination (a). The seedling length was measured after germination for 2 d, 3d, and 5 d (b). Figure S3. Effects of FLU on rice seedling growth. WT seedlings were cultured in water at 25/23 °C (day/night). OsNAC2 overexpression lines (ZUOErN3 and ZUOErN4) were cultured in water containing 80 μmol/L FLU. The images were taken on day 3 (a) and day 5 (b) after germination. Figure S4. Expression level of OsNAC2 under salt stress. The expression of OsNAC2 in rice seedlings grown in 50 mM sodium chloride was assayed by RT-qPCR. RT-qPCR data were normalized using the rice UBI gene and are shown relative to 0 h. Error bars represent SD of three biological replicates.

Table S2. Information of the construction of overexpression and RNAi vectors for rice four AGO1 genes. (DOCX 15 kb)

Table S3. Information of plant AGO1 proteins used for phylogenetic analysis. (DOCX 12 kb)

Table S1. Primers used in this study. (DOCX 27 kb)

The mean irradiance profile has been widely applied in performance analysis and atmospheric channel research for free space optical communication; however, the modeling method and a closed-form expression of the mean irradiance profile under random jitter have rarely been discussed. To the best of our knowledge, this work presents a modeling method and a closed-form expression for a mean irradiance profile under random jitter through the ensemble average principle for the first time. We find that, with an increase in random jitter variance, the mean irradiance profile varied from an approximately Gaussian profile to a flat-topped profile to a hollow profile. These findings were verified using multilayer random phase screen simulations. The model of the mean irradiance profile under random jitter developed in this study will improve the accuracy of performance analysis and atmospheric channel research.

This paper presents two methods, named the irradiance fitting method and the irradiance integration method, for the estimation of refractive index structure constant (Cn2) and extinction coefficient under misalignment. Validations of the methods are carried out based on experimentally obtained speckle images. These two methods are feasible and accurate regardless of whether the optical axis misalignment distance is calibrated, which provides an effective and convenient approach for free space optical communication (FSOC) atmospheric channel research.

Early diagnosis of hepatitis C virus (HCV) infection is still urgently desired as there is a global healthy burden and no vaccine available. In this work, a plasmonic nanoplatform was engineered with catalytic hairpin assembly (CHA) amplification reaction specifically of HCV core protein (HCVcp), G-quadruplex/hemin DNAzyme and nanofibrous membrane together. HCVcp was detected in whole serum at the ultralow concentration of 1.0 × 10−4 pg/mL with naked eye. By testing serum samples from 30 donors with different viral loads, detection sensitivity of the plasmonic nanoplatform turned out to be much better than that of the commercial ELISA kit. In addition, the plasmonic nanoplatform exhibited high specificity, excellent reusability and long-term stability. Naked-eye detection based on the plasmonic nanoplatform is expected to have potential applications in point-of-care testing (POCT) and early diagnosis of hepatitis C and other infectious diseases.

The influences of phase-shift error induced by a 90° space-optical hybrid on the performance of homodyne coherent receivers are analyzed. Phase-shift errors bring a fixed phase difference between the signal and local oscillation (LO) light. For an optical phase-locked loop OPLL, it becomes the third source of phase noise, further increasing loop phase noise. Under the joint action of phase difference and increasing phase noise, the sensitivity of the receiver deteriorates considerably. For a bit error rate (BER) of 10−9, in order to make the additional received power penalty less than 0.5 dB, the phase shift error of each branch must be less than 2°. Further, if the BER is 10−10, the limiting value becomes 1°. This presents a constraint for the design of the 90° space-optical hybrid.

Plant architecture affects grain yield. Overexpressing a version of OsNAC2 resistant to miRNA-mediated degradation increased panicle number and grain yield under field conditions, identifying a new strategy to improve yield., Plant architecture is a major target of rice (Oryza sativa) breeding and selection, but the underlying regulatory networks remain unclear. Here, we overexpressed an OsNAC2 mutant (OErN) that cannot be cleaved by the miRNA miR164b. OErN plants had better plant architecture and longer panicles, and produced more grains. The parental line averaged 12.2 primary and 31.5 secondary branches in the main panicles; two OErN lines averaged 15.0 and 15.2 primary, and 41.5 and 44.3 secondary branches. In large-scale field trials, OErN plants produced at least 58.62% more total grain (by weight) compared with the parental line. They also had more large and small vascular bundles in the stem internodes and leaves. Overexpression of miR164b or down-regulation of OsNAC2 led to decreased panicle length and grain yield in the main panicle. The OErN plants showed significant up-regulation of the grain number and plant architecture-related genes IPA1 and DEP1. A survey of >3000 rice varieties found no natural mutations in the miR164b-binding site of OsNAC2. OErN increased yield in Nipponbare and the commonly grown Yangyujing 3 cultivars. In summary, we identified an efficient new strategy to increase rice yield substantially and improve plant architecture through overexpression of OsmiR164b-resistant OsNAC2.

We get the sailing opportunities of YW 21 and YW22 ships, and carry out the marine atmospheric laser communication channel test and terminal verification experiment. We develop the experimental equipment including marine atmospheric laser communication terminal and the atmospheric parameter measuring equipment. The stability and tracking data of the communication terminal are obtained, and the optical parameters of the channel are measured. In this paper, the experimental results of the key technology of artificial light assisted ATP are presented.

The LEO-Ground FSO link is a unique link in the space-based satellite optical network, in which the capabilities are influenced by the various kinds of atmospheric effects. The atmospheric refraction and beam wander influence on the acquisition are addressed in this research, especially under the scene of large zenith angle in the LEO-Ground link. The model is established and the numerical simulation is carried out in a simplified LEO-Ground link scenario basing on the profile model of pressure and temperature C n 2 . The result shows that the atmospheric refraction and beam wander at large zenith angle will considerable increase required uncertainty cone and total scan time. In addition, the optimal acquisition starting zenith angle for the maximum data transmitting time is also estimated. This research provides an uncertainty cone design method at large zenith angle and presents a suggestion for improving transmitting time.

Both atmospheric extinction coefficient and refractive index structure constant ( C n 2 ) are important parameters to describe laser beam propagation in the atmosphere. The typical measurement methods for these two parameters are separated. Recently an integrated measurement method has been developed with the aperture constraint condition. In this study, a variable aperture method is proposed to simultaneously evaluate the atmospheric extinction coefficient and C n 2 needless to consider the aperture constraint condition. The projection optics with CCD is employed to partially receive atmosphere modulated laser speckle images. Because the extinction coefficient and C n 2 are implicit in the far-field receiving power at a certain aperture, they can be estimated through at least twice measurements of long term speckle at different equivalent aperture on the CCD image. The uncertainty analysis is also carried out. The theoretical and experimental results demonstrate that this technique is feasible, which provides an effective and economical way to understand the complicated behavior of laser beam propagation in the atmosphere.

A method to measure the atmospheric extinction coefficient in the laser beam propagation is proposed based on the projection optics and CCD irradiance response characteristics. In order to compensate the turbulence influence, a refractive index structure constant measurement device is adopted in the measurement. The measurement error sources are also discussed. The experimental results show that this method is feasible and will be helpful for the availability research in the terrestrial free space optical communication. Furthermore, it also has the potential to investigate the various beam shapes’ far field irradiance and link attenuation in the atmospheric propagation.