基于WIA-PA传感器网络的能量有效时间同步算法

WIA-PA协议是一种新型工业级无线传感器网络国际标准。当WIA-PA网络内节点数目增多时,传统的参考广播同步算法RBS以及改进型ERBS算法网络开销非常大。针对这一严峻的问题,提出了一种能量有效的局部最优时间同步算法。该算法对相邻的接收节点在多个参考广播消息的条件下求取平均相位偏差,然后对此平均相位偏差进行最大后验估计,最后根据此估计值调整本地时钟。仿真结果表明,本文所提时间同步算法在同步精度方面比RBS约提高168%,比ERBS约提高24%;同时,同步过程中的网络能耗也大大减少。     

尖晶石铁氧体TixNi1-xFe2O4中阳离子分布和Ti离子磁矩的实验研究

采用固相反应法制备了系列样品Ti_xNi_1-xFe₂O₄ (x=0.0, 0.1, 0.2, 0.3, 0.4). 室温下的X射线衍射谱表明样品全部为(A)[B]₂O₄型单相立方尖晶石结构, 属于空间群Fd3m. 样品的晶格常数随Ti掺杂量的增加而增大. 样品在10 K温度下的比饱和磁化强度σ_S随着Ti掺杂量x的增加逐渐减小. 研究发现, 当Ti掺杂量x≥ 0.2时, 磁化强度σ随温度T的变化曲线出现两个转变温度T_L和T_N. 当温度低于T_N时, 磁化强度明显减小; 当温度达到T_N时, dσ/dT具有最大值. σ-T曲线的这些特征表明, 由于Ti掺杂在样品中出现了附加的反铁磁结构. 这说明样品中的Ti离子不是无磁性的+4价离子, 而是以+2和+3价态存在, 其离子磁矩的方向与Fe和Ni离子的磁矩方向相反. 利用本课题组提出的量子力学方势垒模型拟合样品在10 K温度下的磁矩, 得到了Ti, Fe和Ni三种阳离子在(A)位和[B]位的分布情况, 并发现在所有掺杂样品中, 80%的Ti离子以+2价态占据尖晶石结构的[B]位.     

混合微球谐振腔热非线性效应的增强方法（英文）

提出并实现了一种可增强微球谐振腔热非线性效应的方法。通过在微球谐振腔表面涂覆低折射率紫外胶形成并制备了混合谐振腔。通过分析混合谐振腔结构的热光系数,从理论和实验论证了混合谐振腔结构可获得更大的热非线性效应,同时验证了混合谐振腔的品质因素对热非线性的影响。应用此混合谐振腔结构于温度传感实验,结果表明通过增强方法制备的谐振腔其检测灵敏度提高了2.8倍。因此,此方法在传感应用、生物化学检测、通讯等领域也有广泛的应用前景。     

Fault tolerant deterministic secure quantum communication using logical Bell states against collective noise

This study proposes two novel fault tolerant deterministic secure quantum communication(DSQC) schemes resistant to collective noise using logical Bell states. Either DSQC scheme is constructed based on a new coding function, which is designed by exploiting the property of the corresponding logical Bell states immune to collective-dephasing noise and collective-rotation noise, respectively. The secret message can be encoded by two simple unitary operations and decoded by merely performing Bell measurements, which can make the proposed scheme more convenient in practical applications.Moreover, the strategy of one-step quanta transmission, together with the technique of decoy logical qubits checking not only reduces the influence of other noise existing in a quantum channel, but also guarantees the security of the communication between two legitimate users. The final analysis shows that the proposed schemes are feasible and robust against various well-known attacks over the collective noise channel.     

A Chiral Gold Nanocluster Au20 Protected by Tetradentate Phosphine Ligands

The chirality of a gold nanocluster can be generated from either an intrinsically chiral inorganic core or an achiral inorganic core in a chiral environment. The first structural determination of a gold nanocluster containing an intrinsic chiral inorganic core is reported. The chiral gold nanocluster [Au₂₀(PP₃)₄]Cl₄ (PP₃=tris(2‐(diphenylphosphino)ethyl)phosphine) has been prepared by the reduction of a gold(I)–tetraphosphine precursor in dichloromethane solution. Single‐crystal structural determination reveals that the cluster molecular structure has C₃ symmetry. It consists of a Au₂₀ core consolidated by four peripheral tetraphosphines. The Au₂₀ core can be viewed as the combination of an icosahedral Au₁₃ and a helical Y‐shaped Au₇ motif. The identity of this Au₂₀ cluster is confirmed by ESI‐MS. The chelation of multidentate phosphines enhances the stability of this Au₂₀ cluster.     

The First Five‐Membered‐Heterocycle‐Fused Subphthalocyanine Analogues: Chiral Tri(benzo[b]thiopheno)subporphyrazines

Two tri(benzo[b]thiopheno)subporphyrazine regioisomers with C₃ and C₁ molecular symmetry have been isolated from the cyclotrimerization of benzo[b]thiophene‐2,3‐dicarbonitrile as the first five‐membered‐heterocycle‐fused subphthalocyanine analogues. Optical resolution of both regioisomers was achieved by using a chiral HPLC technique, affording the first chiral subphthalocyanine analogues.     

Chemical and Toxicological Investigations of a Previously Unknown Poisonous European Mushroom Tricholoma terreum

The established tradition of consuming and marketing wild mushrooms has focused attention on mycotoxicity, which has become a global issue. In the present study, we describe the toxins found in a previously unknown poisonous European mushroom Tricholoma terreum. Fifteen new triterpenoids terreolides A–F ( 1 – 6 ) and saponaceolides H–P ( 8 – 16 ) were isolated from the fruiting bodies of the toxic mushroom T. terreum. Terreolides A–C ( 1 – 3 ) possessed a unique 5/6/7 trioxaspiroketal system, whereas terreolides D–F ( 4 – 6 ) possessed an unprecedented carbon skeleton. Two abundant compounds in the mushroom, saponaceolide B ( 7 ) and saponaceolide M ( 13 ), displayed acute toxicity, with LD₅₀ values of 88.3 and 63.7 mg kg^?1 when administered orally in mice. Both compounds were found to increase serum creatine kinase levels in mice, indicating that T. terreum may be the cause of mushroom poisoning ultimately leading to rhabdomyolysis.     

Exceedingly Fast Copper(II)‐Promoted ortho CH Trifluoromethylation of Arenes using TMSCF3

The direct ortho‐trifluoromethylation of arenes, including heteroarenes, with TMSCF₃ has been accomplished by a copper(II)‐promoted C? H activation reaction which completes within 30 minutes. Mechanistic investigations are consistent with the involvement of C? H activation, rather than a simple electrophilic aromatic substitution (S_EAr), as the key step.     

The Divergent Synthesis of Nitrogen Heterocycles by Rhodium(II)‐Catalyzed Cycloadditions of 1‐Sulfonyl 1,2,3‐Triazoles with 1,3‐Dienes

The first rhodium(II)‐catalyzed aza‐[4+3] cycloadditions of 1‐sulfonyl 1,2,3‐triazoles with 1,3‐dienes have been developed, and enable the efficient synthesis of highly functionalized 2,5‐dihydroazepines from readily available precursors. In some cases, the reaction pathway could divert to formal aza‐[3+2] cycloadditions, thus leading to 2,3‐dihydropyrroles. In this context, the titled reaction represents a capable tool for the divergent synthesis of two types of synthetically valuable aza‐heterocycles from common rhodium(II) iminocarbene intermediates.