Enhancing the performance of mode-pairing quantum key distribution by wavelength division multiplexing.

Mode-pairing quantum key distribution (MP-QKD) holds great promise for the practical implementation of QKD in the near future. It combines the security advantages of measurement device independence while still being capable of breaking the Pirandola-Laurenza-Ottaviani-Banchi bound without the need for highly demanding phase-locking and phase-tracking technologies for deployment. In this work, we explore optimization strategies for MP-QKD in a wavelength-division multiplexing scenario. The simulation results reveal that incorporation of multiple wavelengths not only leads to a direct increase in key rate but also enhances the pairing efficiency by employing our novel pairing strategies among different wavelengths. As a result, our work provides a new avenue for the future application and development of MP-QKD.

SRSF2 is required for mRNA splicing during spermatogenesis.

BACKGROUND: RNA splicing plays significant roles in fundamental biological activities. However, our knowledge about the roles of alternative splicing and underlying mechanisms during spermatogenesis is limited. RESULTS: Here, we report that Serine/arginine-rich splicing factor 2 (SRSF2), also known as SC35, plays critical roles in alternative splicing and male reproduction. Male germ cell-specific deletion of Srsf2 by Stra8-Cre caused complete infertility and defective spermatogenesis. Further analyses revealed that deletion of Srsf2 disrupted differentiation and meiosis initiation of spermatogonia. Mechanistically, by combining RNA-seq data with LACE-seq data, we showed that SRSF2 regulatory networks play critical roles in several major events including reproductive development, spermatogenesis, meiotic cell cycle, synapse organization, DNA recombination, chromosome segregation, and male sex differentiation. Furthermore, SRSF2 affected expression and alternative splicing of Stra8, Stag3 and Atr encoding critical factors for spermatogenesis in a direct manner. CONCLUSIONS: Taken together, our results demonstrate that SRSF2 has important functions in spermatogenesis and male fertility by regulating alternative splicing.

Boosting the performance of loss-tolerant measurement-device-independent quantum key distribution.

Measurement-device-independent quantum key distribution can remove all possible detector side channels, and is robust against state preparation flaws when further combined with the loss-tolerant method. However, the secure key rate in this scenario is relatively low, thus hindering its practical application. Here, we first present a four-intensity decoy-state protocol where the signal intensity is modulated only in Z basis for key generation while the decoy intensities are modulated in both Z and X bases for parameter estimation. Moreover, we adopt collective constraint and joint-study strategy in statistical fluctuation analysis. We have also experimentally demonstrated this protocol and the result indicates high performance and good security for practical applications.

Transient inhibition of CDK2 activity prevents oocyte meiosis I completion and egg activation in mouse.

Mammalian oocytes are arrested at the diplotene stage of prophase I during fetal or postnatal development. It was reported that cyclin-dependent kinases (CDK1) was the sole CDK to drive the resumption of meiosis and CDK2 was dispensable for meiosis progression in mouse oocytes according to the conditional knockout studies. However, a recent study showed that CDK2 activity is essential for meiotic division and gametogenesis by means of gene-directed mutagenesis, which avoids the compensatory activation of other CDKs. Taken the compensatory effect between CDKs after gene knockout, the physiological function of CDK2 activity in oocyte maturation remains unclear. To address this issue, we applied a specific small-molecule inhibitor to restrain CDK2 activity transiently during oocyte meiotic maturation. Surprisingly, transient inhibition of CDK2 activity severely prevented the meiosis I completion although the meiotic resumption was not affected. Then we found that CDK2 activity was required for establishment of normal spindle and chromosome dynamics. Notably, CDK2 inhibition interrupted the anaphase-promoting complex/cyclosome (APC/C)-dependent degradation pathway by maintaining the activation of spindle assembly checkpoint (SAC). Interestingly, CDK2 inhibition prevented the egg activation as well. Overall, our data demonstrate that CDK2 kinase activity is required for proper dynamics of spindle and chromosomes, whose disturbance induces the continuous SAC activation and subsequent inactivation of APC/C activity in oocyte meiosis.

The cyclin B2/CDK1 complex inhibits separase activity in mouse oocyte meiosis I.

Chromosome segregation is driven by separase, activity of which is inhibited by binding to securin and cyclin B1/CDK1. In meiosis, premature separase activity will induce aneuploidy or abolish chromosome segregation owing to the untimely destruction of cohesin. Recently, we have proved that cyclin B2 can compensate for cyclin B1 in CDK1 activation for the oocyte meiosis G2/M transition. In the present study, we identify an interaction between cyclin B2/CDK1 and separase in mouse oocytes. We find that cyclin B2 degradation is required for separase activation during the metaphase I-anaphase I transition because the presence of stable cyclin B2 leads to failure of homologous chromosome separation and to metaphase I arrest, especially in the simultaneous absence of securin and cyclin B1. Moreover, non-phosphorylatable separase rescues the separation of homologous chromosomes in stable cyclin B2-arrested cyclin B1-null oocytes. Our results indicate that cyclin B2/CDK1 is also responsible for separase inhibition via inhibitory phosphorylation to regulate chromosome separation in oocyte meiosis, which may not occur in other cell types.

Proof-of-principle demonstration of sequential 3 → 1 quantum random access code via cascaded measurements.

Quantum random access code (QRAC) serves the communication task to encode a long message into a quantum system and allow the receiver to decode the initial information with a higher success probability than classical random access code (RAC). Here, we present an experimental demonstration of sequential 3 → 1 QRAC in the prepare-transform-measure scenario with one sender and three independent receivers. The experimental results show that, in the 3 → 1 QRAC scenario, three receivers can independently decode the initial information with an average success probability higher than the classical RAC.

Experimental demonstration of tomography-based quantum key distribution.

Tomography is a very beneficial and fundamental technique in the fields of quantum information and quantum optics, which can be applied to infer information about quantum states or quantum processes. In quantum key distribution (QKD), tomography can be proposed to improve the secure key rate by taking full advantage of data from both matched and mismatched measurement outcomes to characterize quantum channels accurately. However, to date, no experimental work has been conducted on it. In this work, we study tomography-based QKD (TB-QKD), and for the first time, to the best of our knowledge, carry out proof-of-principle experimental demonstrations by implementing Sagnac interferometers to simulate different transmission channels. Furthermore, we compare it with reference-frame-independent QKD (RFI-QKD) and demonstrate that TB-QKD can significantly outperform RFI-QKD in certain channels, e.g., amplitude damping channel or probabilistic rotation channel.

Measurement-device-independent quantum key distribution with insecure sources.

Measurement-device-independent quantum key distribution (MDI-QKD) can remove all detection side channels but still makes additional assumptions on sources that can be compromised through uncharacterized side channels in practice. Here, we combine a recently proposed reference technique to prove the security of MDI-QKD against possible source imperfections and/or side channels. This requires some reference states and an upper bound on the parameter that describes the quality of the sources. With this formalism we investigate the asymptotic performance of single-photon sources, and the results show that the side channels have a great impact on the key rates.

Development of novel polymorphic microsatellite markers for Picea brachytyla.

BACKGROUND: Picea brachytyla is a unique tree species in China. Due to being extensively exploited in the past, it is listed as Vulnerable in the IUCN Red List. It is mainly distributed across the Hengduan and Daba-Qinglin mountains and has been found in other areas including Sichuan Province and Qinghai Province, China. Microsatellites, or simple sequence repeats (SSRs), are widely used in correlational studies of genetic protection. Few markers have been developed for P. brachytyla because of the small number of trees and scholarly resources available for study. METHODS AND RESULTS: The genomic DNA of P. brachytyla was sequenced using the DNBSEQ platform, and unigenes were obtained after assembly and deredundancy. Of the 100 primer pairs screened, we isolated 10 useful microsatellite loci from P. brachytyla genes. The observed and expected heterozygosity values ranged from 0.173 (P24) to 0.788 (P79; mean 0.469) and 0.199 (P87) to 0.911 (P79; mean 0.700), respectively. Polymorphism-information content (PIC) ranged from 0.190 (P84) to 0.904 (P79; mean 0.666). Only P84 and P72 were in a Hardy-Weinberg equilibrium (P > 0.05) in the different P. brachytyla populations. All the levels of linkage disequilibrium (LD) were high for the 10 SSR loci indicating that there were no autocorrelations among the 10 SSR loci. CONCLUSIONS: The novel polymorphic microsatellite markers showed high polymorphism for P. brachytyla. These polymorphic microsatellites can provide a basis for future conservation and genetic research on this rare plant species.

Strategies to enhance the reactivity of zero-valent iron for environmental remediation: A review.

Application of zero-valent iron (ZVI) has become one of the most promising innovative technologies for the remediation of environmental pollutants. However, ZVI may suffer from the low intrinsic reactivity toward refractory pollutants, which seriously restricts its practical application in fields. Therefore, strategies have been developing to enhance the reactivity of ZVI. Until now, the most commonly used strategies include pretreatment of ZVI, synthesis of highly-active ZVI-based materials and additional auxiliary measures. In this review, a systematic and comprehensive summary of these commonly used strategies has been conducted for the following purposes: (1) to understand the fundamental mechanisms of the selected approaches; (2) to point out their advantages and shortcomings; (3) to illustrate the main problems of their large-scale application; (4) to forecast the future trend of developing ZVI technologies. Overall, this review is devoted to providing a fundamental understanding on the mechanism for enhancing the reactivity of ZVI and facilitating the practical application of ZVI technologies in fields.