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Stereodivergently asymmetric synthesis of chiral phosphorus compounds by synergistic combination of ion-pair catalyst and base

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Science China Chemistry 2022年第12期65卷 2500-2511页

作者： Hui-Lin Hu Xiaoyu Ren jiajia he Lixiang Zhu Siqiang Fang Zhishan Su Tianli Wang Key Laboratory of Green Chemistry&Technology Ministry of EducationCollege of ChemistrySichuan UniversityChengdu610064China

Stereodivergently constructing the designed products having adjacent multi-stereocenters via a given reaction,with excellent control of both absolute and relative configurations,presents one of the substantial hurdles in asymmetric ***,we report a precisely stereodivergent asymmetric protocol by synergistic combination of phosphonium-involved ion-pair catalysis and base for accessing to chiral phosphorus compounds bearing two adjacent chiral centers particularly containing an acidic protonated enantioenriched carbon atom,having broad functional group compatibility in both dynamic and thermodynamic processes under mild reaction *** keys for the success in constructing these stereoisomers with high levels of regio-,diastereo-,and enantioselectivities were contained:firstly,the precise stereo-control in providing dynamic products was enabled by bifunctional phosphonium salt catalyst with semi-enclosed cavity;secondly,the readily stereospecific transformation of adducts from dynamic to thermodynamic version was initiated by achiral *** four stereoisomers could be readily accessed even in gram-scale in high yields with maintaining excellent stereoselectivities,illustrating the potential of this synergistic catalytic methodology in organic ***,mechanistic studies including density functional theory(DFT)calculations and control experiments provide insights into the mechanism.

关键词： stereodivergent asymmetric synthesis chiral phosphorus compounds dipeptided phosphonium salts cooperative catalysis base control

TwoMADS-boxgenes regulate vascularcambium activity and secondary growth by modulating auxin homeostasis in Populus

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Plant Communications 2021年第5期2卷 120-131页

作者： Shuai Zheng jiajia he Zengshun Lin Yingying Zhu Jiayan Sun Laigeng Li National Key Laboratory of Plant Molecular Genetics and CAS Center for Excellence in Molecular Plant Sciences Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghai 200032China University of the Chinese Academy of Sciences Beijing 100049China Hunan Agricultural University Hunan 4101287China Lanzhou University Lanzhou730000China

In trees,stem secondary growth depends on vascular cambium proliferation activity and subsequent cell differentiation,in which an auxin concentration gradient across the cambium area plays a crucial role in regulating the ***,the underlying molecular mechanismfor the establishment of auxin concentration is not fully *** this study,we identified two function-unknown MADS-box genes,VCM1 and VCM2,which are expressed specifically in the vascular cambium and modulate the subcellular homeostasis of *** knockdown of both VCM1 and VCM2 enhanced vascular cambium proliferation activity and subsequent xylem *** of VCM1 suppressed vascular cambium activity and wood formation by regulating PIN5 expression,which tuned the soluble auxin concentration in the vascular cambium *** study reveals the role of VCM1 and VCM2 in regulating the proliferation activity of the vascular cambium and secondary growth by modulating the subcellular auxin homeostasis in Populus.

关键词： vascular cambium secondary growth auxin xylem tree

Measurement of laminar burning velocities and analysis of flame stabilities for hydrogen-air-diluent premixed mixtures

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Chinese Science Bulletin 2009年第5期54卷 846-857页

作者： HU ErJiang HUANG ZuoHua he jiajia JIN Chun MIAO HaiYan WANG XiBin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The laminar burning velocities and Markstein lengths of the hydrogen-air-diluent mixtures were meas-ured at different equivalence ratios (0.4―1.5), different diluents (N2, CO2 and 15%CO2+85%N2) and di-lution ratios (0, 0.05, 0.10 and 0.15) by using the outwardly expanding flame. The influences of flame stretch rate on the flame propagation characteristics were analyzed. The results show that both the laminar burning velocities and the Markstein lengths of the hydrogen-air-diluent mixtures decrease with the increase of dilution ratio. The decrease in Markstein lengths means that adding diluents into the hydrogen-air mixtures will decrease the diffusional-thermal instability of the flame front. For a specified dilution ratio, the laminar burning velocities give their maximum values at an equivalence ratio of 1.8. The Markstein lengths increase with the increase of the equivalence ratio monotonously regardless of the diluents. The study shows that CO2 as the diluent has a greater impact on the laminar flame speed and the flame front stability than N2 as the diluent.

关键词：氢气空气混合火焰特性燃烧速度稳定性

Controlled synthesis of Mn_(x)Cd_(1-x)S for enhanced visible-light driven photocatalytic hydrogen evolution

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Chinese Journal of Structural Chemistry 2023年第8期42卷 37-46页

作者： Yuxin Sun Ye Li jiajia he Liuyun Chen Hongbing Ji Zuzeng Qin Tongming Su School of Chemistry and Chemical Engineering Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification TechnologyGuangxi UniversityNanning530004PR China Fine Chemical Industry Research Institute School of ChemistrySun Yat-sen UniversityGuangzhou510275PR China

Ternary sulfide solid solutions have garnered great attention in photocatalytic water splitting due to their tunable electronic property,low cost,and sufficient light-absorption ***,a series of Mn_(x)Cd_(1-x)S samples with different Mn/Cd molar ratios were synthesized by solvothermal method and used for photocatalytic hydrogen production under visible *** Mn_(0.2)Cd_(0.8)S and Mn_(0.4)Cd_(0.6)S are demonstrated to be the solid so-lutions,while Mn_(0.6)Cd_(0.4)S and Mn_(0.8)Cd_(0.2)S consist of Mn_(x)Cd_(1-x)S solid solution and *** addition,the Mn_(0.4)Cd_(0.6)S exhibits the highest photocatalytic performance with the H_(2) production rate of 185.95μmol·h^(-1),which is 4.7 times higher than that of *** cocatalyst,the quantum efficiency of Mn_(0.4)Cd_(0.6)S reaches 2.04%at 400 *** addition,the Mn_(0.4)Cd_(0.6)S solid solution also shows high stability during the photocatalytic H_(2) production *** effect of Mn/Cd molar ratio on the microstructure,band gap structure,and photo-catalytic hydrogen production performance of Mn_(x)Cd_(1-x)S was revealed *** excellent photo-catalytic H_(2) production performance of Mn_(0.4)Cd_(0.6)S solid solution is mainly due to its enhanced reducing potential and high charge separation efficiency.

关键词： Mn_(x)Cd_(1-x)S Solid solution Photocatalytic Water splitting Hydrogen

Blown sand motion within the sand-control system in the southern section of the Taklimakan Desert Highway

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Journal of Arid Land 2015年第5期7卷 599-611页

作者： CheNG Hong he jiajia XU Xingri ZOU Xueyong WU Yongqiu LIU Chenchen DONG Yifan PAN Meihui WANG Yanzai ZHANG Hongyan State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University MOE Engineering Center of Desertification and Blown-sand Control at Beijing Normal University Lushunkou Trading Center of Land Reserve

Although scientists have performed many studies in the Taklimakan Desert, few of them have reported the blown sand motion along the southern edge of the Taklimakan Desert Highway, which differs significantly from the northern region in terms of aeolian sand geomorphology and formation environment. Based on the field ob- servation data of airflow and aeolian sand transport, continuous monitoring data of erosional and depositional processes between 14 April 2009 and 9 April 2011 and data of surface sand grains from the classical section along the southern edge of the Taklimakan Desert Highway, this paper reported the blown sand motion within the sand-control system of the highway. The main results are as follows： 1） The existing sand-control system is highly effective in preventing and controlling desertification. Wind velocities within the sand-control system were ap- proximately 33%-100% of those for the same height above the mobile sand surface. Aeolian sand fluxes were approximately 0-31.21% of those of the mobile sand surface. Sand grains inside the system, with a mean diameter of 2.89 q）, were finer than those （2.15 q）） outside the system. In addition, wind velocities basically followed a loga- rithmic law, but the airflow along the classical section was mainly determined by topography and vegetation. 2） There were obvious erosional and depositional phenomena above the surface within the sand-control system, and these phenomena have very consistent patterns for all observation points in the two observed years. The total thicknesses of erosion and deposition ranged from 0.30 to 14.60 cm, with a mean value of 3.67 cm. In contrast, the deposition thicknesses were 1.90-22.10 cm, with a mean value of 7.59 cm, and the erosion thicknesses were 3.51-15.10 cm, with a mean value of 8.75 cm. The results will aid our understanding of blown sand within the sand-control system and provide a strong foundation for optimizing the sand-control system.

关键词： sand-control system blown sand motion erosion deposition Taklimakan Desert Highway

High expression of PPP2R3A predicts poor outcome in hepatocellular carcinoma patients after liver transplantation

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High expression of PPP2R3A predicts poor outcome in hepatoce...

2021年中国肿瘤标志物学术大会暨第十五届肿瘤标志物青年科学家论坛

作者： jiajia he Qing Zhang Ning Jiao Shuang Qiu The Third Medical Center of Chinese PLA General Hospital

BACKGROUND: Protein phosphatase 2 regulatory subunit B alpha(PPP2 R3 A) gene has been reported in other tumors, but the influence of PPP2 R3 A gene expression on the occurrence, development, and prognosis of hepatocellular carcinoma(HCC) remains ***: To investigate whether the PPP2 R3 A gene could be used to predict tumor recurrence and survival of HCC patients after liver transplantation(LT).METHODS: Collected diseased liver tissues of HCC patients after LT, as well as their clinical data and follow-up information. The immunohistochemical method was used to detect the expression of PPP2 R3 A protein in the tissues of 108 patients with primary liver cancer. The c2 test was used to analyze the relationship between PPP2 R3 A protein expression levels and the clinicopathological features of tumors. The Kaplan-Meier method was used to analyze overall postoperative survival. The COX proportional hazard model was used to analyze adverse prognostic ***: Immunohistochemistry showed that the PPP2 R3 A protein was mainly expressed in the cytoplasm of HCC cells. Compared to corresponding peritumoral tissues, expression was higher in HCC tissues(P≤0.001). Correlation analysis showed that high PPP2 R3 A expression was correlated with preoperative serum alpha-fetoprotein(AFP) levels(P=0.003), TNM-t stage(P≤0.001) and envelope invasion(P=0.001). Univariate analysis showed that overall survival(P≤0.001) and recurrence-free survival(P=0.025) of patients with high PPP2 R3 A expression(≥ 4 points) were poor compared to those with low expression(he overall survival rate or recurrence-free survival rate at 1, 2, and 3 years with high PPP2 R3 A expression were 73%, 38%, and 23%, or 31%,23%, and 23% respectively. Multivariate analysis showed that high PPP2 R3 A expression(HR = 2.900,95%CI: 1.411–5.960, P=0.004) was an independent survival risk factor of HCC patients after LT, and it was also an independent predictor of postoperative tumor recurrence. This

关键词： Protein phosphatase 2 regulatory subunit B' ' α hepatocellular carcinoma Liver transplantation Prognosis Alpha-fetal protein

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混合励磁型无轴承磁通切换电机损耗最小控制

电机与控制学报 2023年第9期27卷 53-62页

作者：何佳佳周扬忠福州大学福建省新能源发电与电能变换重点实验室福建福州350108

混合励磁型无轴承磁通切换电机(BFSheM)的电枢绕组需要同时流过转矩电流和悬浮电流,通常有着较大的绕组发热量及系统损耗量,制约着电机效率的进一步提升。针对上述问题,以12槽/10极BFSheM为研究对象,通过合理分配电枢电流和励磁电流的占... 详细信息

混合励磁型无轴承磁通切换电机(BFSheM)的电枢绕组需要同时流过转矩电流和悬浮电流,通常有着较大的绕组发热量及系统损耗量,制约着电机效率的进一步提升。针对上述问题,以12槽/10极BFSheM为研究对象,通过合理分配电枢电流和励磁电流的占比,构建BFSheM损耗最小控制策略以实现电机系统的总损耗最小。首先利用有限元仿真分析电机的铜耗及铁耗,从而确定影响电机损耗的可控电磁变量。由于影响BFSheM铁耗的电磁变量较多,且各变量间耦合较强,鉴于现有铁耗模型难以兼顾BFSheM铁耗计算的精度与速度要求,提出利用BP神经网络拟合出铁耗与各电磁变量的响应模型,之后使用广义模式直接搜索算法在线求解BFSheM损耗模型的最优解,最后通过BFSheM控制系统输出能够实现电机最小损耗的最优电流分配值。仿真及实验结果表明,BFSheM损耗最小控制能够有效减少电机总损耗,减轻电枢绕组散热压力,提升电机输出效率,具有良好的应用前景。

关键词：混合励磁无轴承磁通切换电机损耗最小控制 BP神经网络铁耗模型广义模式搜寻

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Resting-state brain network remodeling after different nerve reconstruction surgeries:a functional magnetic resonance imaging study in brachial plexus injury rats

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Neural Regeneration Research 2025年第5期20卷 1495-1504页

作者： Yunting Xiang Xiangxin Xing Xuyun Hua Yuwen Zhang Xin Xue jiajia Wu Mouxiong Zheng he Wang Jianguang Xu School of Rehabilitation Science Shanghai University of Traditional Chinese MedicineShanghaiChina Engineering Research Center of Traditional Chinese Medicine Intelligent Rehabilitation Ministry of EducationShanghaiChina Department of Rehabilitation Medicine Yueyang Hospital of Integrated Traditional Chinese and Western MedicineShanghai University of Traditional Chinese MedicineShanghaiChina Department of Traumatology and Orthopedics Yueyang Hospital of Integrated Traditional Chinese and Western MedicineShanghai University of Traditional Chinese MedicineShanghaiChina Institute of Science and Technology for Brain-Inspired Intelligence Fudan UniversityShanghaiChina Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence(Fudan University) Ministry of EducationShanghaiChina Human Phenome Institute Fudan UniversityShanghaiChina

Distinct brain remodeling has been found after different nerve reconstruction strategies,including motor representation of the affected ***,differences among reconstruction strategies at the brain network level have not been *** study aimed to explore intranetwork changes related to altered peripheral neural pathways after different nerve reconstruction surgeries,including nerve repair,endto-end nerve transfer,and end-to-side nerve ***–Dawley rats underwent complete left brachial plexus transection and were divided into four equal groups of eight:no nerve repair,grafted nerve repair,phrenic nerve end-to-end transfer,and end-to-side transfer with a graft sutured to the anterior upper ***-state brain functional magnetic resonance imaging was obtained 7 months after *** independent component analysis algorithm was utilized to identify group-level network components of interest and extract resting-state functional connectivity values of each voxel within the *** in intra-network resting-state functional connectivity were compared among the *** muscle reinnervation was assessed by behavioral observation(elbow flexion)and *** results showed that alterations in the sensorimotor and interoception networks were mostly related to changes in the peripheral neural *** repair was related to enhanced connectivity within the sensorimotor network,while end-to-side nerve transfer might be more beneficial for restoring control over the affected limb by the original motor *** thalamic-cortical pathway was enhanced within the interoception network after nerve repair and end-to-end nerve *** areas related to cognition and emotion were enhanced after end-to-side nerve *** study revealed important brain networks related to different nerve *** networks may be potential targets for enhancing motor recovery.

关键词： brain functional networks end-to-end nerve transfer end-to-side nerve transfer independent component analysis nerve repair peripheral plexus injury resting-state functional connectivity

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改进U-net++的遥感图像语义分割方法

计算机工程与应用 2024年第13期60卷 255-265页

作者：何佳佳徐杨张永丹贵州大学大数据与信息工程学院贵阳550025 贵阳铝镁设计研究院有限公司贵阳550009

遥感图像语义分割在土地资源规划、智慧城市等领域有着广泛的应用。由于高分辨率遥感的图像存在边界分割不清、小尺寸目标分割不清等问题,为此提出了一种基于U-net++的改进网络TU-net,该模型通过优化网络结构加强模型的特征提取能力,引... 详细信息

遥感图像语义分割在土地资源规划、智慧城市等领域有着广泛的应用。由于高分辨率遥感的图像存在边界分割不清、小尺寸目标分割不清等问题,为此提出了一种基于U-net++的改进网络TU-net,该模型通过优化网络结构加强模型的特征提取能力,引入特征头细化模块,通过构建了两条通道来增强通道特征表示和空间特征表示,提升了对高层语义信息的解析能力;引入基于Transformer的注意力聚合模块来捕捉全局上下文信息,设计了十字窗交互模块,显著降低了计算复杂度;在解码器末端设计了一个动态特征融合块,以此得到多类、多尺度的语义信息,增强最终的分割效果。TU-net在两个数据集上进行实验,其中OA、mIoU、mF1分数均高于主流模型,Vaihingen数据集中小尺寸目标车的IoU和F1分数分别为0.896和0.962,比次优模型提升了5%和15.8%;Potsdam数据集中树的IoU和F1分数分别为0.913和0.936,比次优模型提升了6.3%和4.3%,实验结果表明该模型能够更精准地分割小尺寸目标及目标边界。

关键词：高分辨率遥感的图像语义分割小尺寸目标特征头细化模块十字窗交互模块动态特征融合块