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为了实现相位调制光信号的相位混合运算（2θA-θB、2θB-θA）,描述了简并四波混频光互调效应的工作原理,给出了泵浦消耗情形下四波混频闲频光振幅和相位的解析表达式。重点研究了基于高非线性光纤的相位混合运算器件的实现方案,以四进制相位信号为例分析了输入光幅度噪声对两种相位互调运算结果的影响。仿真计算表明,该运算器件的光噪声指数（光信噪比的劣化）约为6.6dB;当输入光信噪比不低于25dB时,两种运算的符号错误率均低于10-3,对应的误差矢量振幅约为22%。

目的 探讨颞浅动脉-大脑中动脉端侧吻合术中不同临时阻断技术的效果及可靠性。 方法 回顾性分析2015年1月—2023年4月南方医科大学南方医院神经外科收治的接受直接搭桥术治疗的烟雾病患者资料，根据临时阻断策略的不同将患者分为3组：①有垫片、多阻断夹阻断组（multi-clips+rubber pad group，M+R组）；②无垫片、多阻断夹阻断组（multi-clips group，M组）；③无垫片、单阻断夹阻断组（single-clip group，S组）。比较组间临时阻断时间、受体动脉切开后有无渗血、术中穿支血管损伤以及术后新发脑梗死情况。 结果 共355例患者、360个大脑半球纳入分析，按大脑半球统计患者360例，其中男性188例，女性172例，平均年龄为（43.8±0.7）岁。其中M+R组45例，M组191例，S组124例。3组平均阻断时间：M+R组为（37.9±9.8）min，M组为（20.9±9.0）min，S组为（11.0±3.5）min，组间差异有统计学意义（P＜0.001）。阻断后受体动脉管腔内渗血以及术中穿支血管损伤发生率：M+R组为8.89%（阻断后受体动脉渗血4例），M组为14.66%（阻断后受体动脉渗血19例，术中穿支血管损伤8例，临时阻断部位有血栓形成1例），S组为5.65%（阻断后受体动脉渗血7例），组间差异无统计学意义（P>0.05）。术后新发脑梗死发生率差异无统计学意义（P>0.05）。 结论 单阻断夹阻断策略安全、有效，能显著缩短临时阻断时间，可以优先考虑作为颞浅动脉-大脑中动脉端侧吻合过程中的临时阻断策略。 Abstract: Objective To investigate the effects and reliability of different temporary occlusion techniques in end-to-side anastomosis of the superficial temporal artery-middle cerebral artery. Methods A retrospective analysis was conducted on the data of patients with Moyamoya disease who underwent direct bypass surgery in the Department of Neurosurgery, Nanfang Hospital, Southern Medical University, from January 2015 to April 2023. The patients were divided into three groups according to the different temporary occlusion strategies: ①multi-clips+rubber pad group (M+R group); ②multi-clips group (M group); and ③single-clip group (S group). Temporary occlusion time, presence of errhysis after recipient artery incision, intraoperative perforator vessel injury, and postoperative novel cerebral infarction were compared among the three groups. Results A total of 355 patients and 360 cerebral hemispheres were included in the analysis, and 360 patients were counted according to the number of cerebral hemispheres, including 188 males and 172 females, with an average age of (43.8±0.7) years. There were 45 cases in the M+R group, 191 cases in the M group, and 124 cases in the S group. The average occlusion time were (37.9±9.8) minutes in the M+R group, (20.9±9.0) minutes in the M group, and (11.0±3.5) minutes in the S group, with significant differences between the groups (P0.05). There was no significant difference in the incidence of novel cerebral infarctions postoperatively (P>0.05). Conclusions The single-clip occlusion strategy is safe and effective, which significantly shortens the temporary occlusion time, and should be prioritized as the temporary occlusion technique in end-to-side anastomosis of the superficial temporal artery-middle cerebral artery.

[Objectives] In response to the impact of fragmented fields and obstacles on agricultural robot operations in hilly areas, this study aimed to propose a multi field block path planning method based on a combination of improved ant colony algorithm and A algorithm. [Methods] By using drones to construct remote sensing images of farmland, using grid method to model the environment of farmland, and then dividing and merging sub regions, a region heuristic function was introduced into the ant colony algorithm to distinguish the movement costs in different regions. The pheromone update method was improved by manually increasing the concentration of pheromones in the optimal path and establishing an adaptive pheromone volatilization coefficient, in order to solve the optimal traversal order of job sub intervals. The A algorithm with heuristic search function was used for sub region connection path planning, ultimately achieving multi field path planning. [Results] The MATLAB simulation test results showed that when the number of sub regions was 40, the average path length planned using the improved ant colony algorithm was reduced by 3.19% compared to the traditional ant colony algorithm, and the average iteration convergence number was reduced by 79.5%. In the path traversal simulation experiment, the coverage rate of the agricultural robot's traversal path could reach 100%, and the path repetition rate was 6.48%. The effectiveness of this method was further verified through simulation experiments of natural environment using remote sensing images of agricultural drones and field operation parameters. [Conclusions] The method proposed in this study could effectively solve the multi field path planning problem of agricultural robots in hilly areas, and provided path reference and technical support for large-scale operation of agricultural robots in hilly areas. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Stroke is the property of Chinese Journal of Stroke Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Nucleophilic aromatic substitution reactions play a crucial role in the synthesis of organic compounds and are considered to be one of the most important synthetic transformations. Traditionally, these reactions have been described as stepwise processes in textbooks. However, with further research, the existence of concerted nucleophilic aromatic substitution reactions has been widely confirmed. This paper provides a brief overview of the stepwise pathway of nucleophilic aromatic substitution reactions and focuses on several examples of concerted reactions, highlighting the importance of reaction design in mechanistic studies. Integrating cutting-edge research findings into teaching can enhance students’ understanding of nucleophilic aromatic substitution reactions. [ABSTRACT FROM AUTHOR]

Objective To investigate the effect of core decompression combined with bone-morphogenetic proteins （BMP） activity inducing rod implantation in the treatment of early-stage femoral head necrosis. Methods Retrospective analysis of 116 patients with early-stage femoral head necrosis from June 2018 to June 2022 were divided into core decompression combined with BMP activity inducing rod group （BMP group） and allograft bone group. Sixty cases in the BMP group were treated with core decompression combined with implantation of BMP-activated induced rods， and 56 cases in the allograft group were treated with core decompression combined with bone grafting of the allograft bone by punching and compression.The differences in hip Harris scores and visual analogue scores （VAS） of pain between the two groups at preoperative，6 months postoperative and 1 year postoperative, and the patient treatment response and femoral head survival rate at 1 year postoperative were compared. Results All patients were followed-up， and the difference between the preoperative VAS score and Harris score of the two groups was not statistically significant （P > 0.05), and the VAS score and Harris score of the two groups were significantly improved at 6 months and 1 year after operation， and the BMP group was better than the allograft bone group, with significant difference（P < 0.05）. At 1 year after surgery, the Harris hip score excellence rate of the BMP group was higher than that of the allograft bone group， and the difference was statistically significant （P < 0.05）； the femoral head survival rate of the BMP group was higher than that of the allograft bone group, and the difference was statistically significant （P < 0.05）. Conclusions Core decompression combined with BMP activity induced rod implantation was effective in the treatment of early femoral head necrosis, which accelerated the induction of new bone formation， improved the quality of new bone, provided biomechanical support for the femoral head, and effectively avoided femoral head collapse. Moreover， it has good biocompatibility and couldbe degraded and absorbed in the body, which is worthy of clinical promotion. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Capital Normal University (Natural Science Edition) is the property of Journal of Capital Normal University (Natural Science Edition) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Copyright of Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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The stability evaluation of the embankment supported by rigid pile composite foundation is a hot and difficult problem in recent years. Based on the plastic deformation theory of Ito T and the soil arching effect, from the perspective of whether the soft soil between the rigid piles will cause sliding failure, the passive load distribution mode of a single row of rigid piles under the embankment load is deduced. Take the upper bound theorem of limit analysis as the framework, based on the internal and external functional balance relationship of the single-row pile-reinforced embankment rotating failure mechanism, a constraint equation with the safety factor as the objective function is constructed. Numerical simulation verifies the rationality of the method. The calculation results show that when the potential failure surface of the embankment passes through the single-row pile, the location of the single-row pile reinforcement moves from the toe of the embankment slope to the center of the embankment, and its safety factor generally shows a trend of first increasing and then decreasing. The maximum reinforcement ratio of a single row of piles is not affected by the height of the embankment. However, it increases with the decrease of the shear strength of soft foundation, and decreases with the decrease of the embankment slope rate. The optimal reinforcement position of a single row of piles is affected significantly by the embankment stacking height, the embankment slope rate, and the friction angle of the foundation, but less affected by the cohesion of the foundation soil. The research results provide a new idea and theoretical support for the stability calculation of rigid pile-supported embankments. [ABSTRACT FROM AUTHOR]

Considering the problem of icing in civil aircraft flying at high altitudes and in cold areas, the composite coating was prepared by doping a certain content of carbon nanotubes (CNT) in Epoxy resin (Ep), which optimised and improved the de-icing performance of civil aircraft. At the same time, the anti-corrosion performance of the CNT-modified Ep on the wing skin was investigated. The test shows that when the CNT content is 0. 5%, the photothermal performance of the composite is good, and the temperature rise is obvious. The photothermal cycling stability test shows that when the CNT content is 0. 5%, the composite coating has photothermal stability under 150 mW/ cm² light. The self-healing performance analysis test shows that after a certain degree of surface damage, the composite coating can achieve self-healing by heating. In the polarisation curve analysis of the electrochemical station (CHI660E) test, the maximum corrosion potential of the composite coating with 0. 5% CNT content is - 1. 510 V, indicating the lowest corrosion rate compared to others. In the static full immersion test, the composite coating with 0. 5% CNT content is reduced the least, indicating its good corrosion resistance. [ABSTRACT FROM AUTHOR]

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The structures and energies of various common carbocations, allylic carbocations, and particularly stable α-amino and α-hydroxyl carbocations were calculated using DFT (density functional theory). The results showed that common carbocations are stabilized by the formation of supercovalent structures, rearrangement, and superconjugation effects, whereas allylic carbocations are stabilized by conjugate effects. The stabilities of α-hydroxyl and α-amino carbocations are particularly high and are equivalent to or higher than that of cyclopropylene carbocation. Finally, different methods of carbocation stabilization using amino and hydroxyl groups are suggested. [ABSTRACT FROM AUTHOR]

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