调控铝在ITH沸石骨架中的位置以用于催化甲醇制烯烃

随着低碳烯烃需求量的增加,甲醇制烯烃(MTO)成为由非石油资源制取低碳烯烃的关键技术,其中沸石由于具有可调节的酸度、有序的微孔结构和较好的择型性能而被广泛用作MTO反应催化剂.ITQ-13沸石(ITH拓扑结构)由于其独特的九元环结构在MTO反应中表现出较好的丙烯选择性和反应寿命,引起了广泛关注.研究表明,分子筛的酸中心分布与MTO反应性能密切相关,因此,研究ITQ-13沸石中铝分布与MTO反应性能的关系,对进一步提升其MTO催化性能具有重要意义.本文分别以与ITH具有共同基本结构单元(双四元环,D4Rs)的LTA沸石(LTA-ITH)和薄水铝石(C-ITH)为铝源,合成了两类铝硅酸盐ITH沸石.X射线衍射、扫描电子显微镜以及氮气吸脱附表征结果表明,这两类分子筛具有相似的片状形貌和微孔性质.氨气程序升温脱附结果表明,具有相近硅铝比的两类ITH沸石具有相近的酸量.进一步采用27Al魔角旋转核磁共振(MAS NMR)、密度泛函理论计算和1-己烯裂解反应对两类ITH分子筛的铝分布进行研究.结果表明,两类分子筛具有不同的铝分布,LTA-ITH中有更多的铝进入ITH的正弦孔道与直孔道,而C-ITH中有更多的铝分布在交叉孔道.当前,研究者普遍认为MTO反应过程遵循双循环烃池机理,ITH交叉孔道由于具有较大的空间,相比于正弦孔道和直孔道,更有利于芳烃循环中间体的产生,从而有利于形成芳烃循环产物(乙烯),而正弦孔道和直孔道却更有利于烯烃循环过程,导致产生更多的丙烯.对两类ITH进行了MTO催化性能测试,结果表明,LTA-ITH比C-ITH表现出更高的丙烯选择性,并且表现出更高的丙烯与乙烯的比率,表明其烯烃循环过程得到加强,这与^(27)Al MAS NMR以及1-己烯裂解反应得到的结论一致,进一步证明ITH分子筛的铝分布得到有效调控.综上,本文阐明了ITH沸石中铝分布与其反应性能的关系,为调整沸石骨架中的Al位点提供一种新策略,为未来制备高效的MTO沸石基催化剂提供参考.

Polo-like kinase 1 suppresses lung adenocarcinoma immunity throughnecroptosis

Polo-like kinase 1(PLK1)plays a crucial role in cell mitosis and has been associated with necroptosis.However,the role of PLK1 and necroptosis in lung adenocarcinoma(LA)remains unclear.In this study,we analyzed The Cancer Genome Atlas(TCGA)and Genotype-Tissue Expression databases to evaluate the prognostic value and mechanistic role of PLK1 in LA.PLK1 was found to be highly expressed in LA and was positively associated with advanced disease staging and poor survival outcomes.Functional enrichment analysis showed that PLK1 was involved in cell mitosis,neurotransmitter transmission,and drug metabolism.Further analysis using single-sample gene set enrichment analysis and ESTIMATE algorithm revealed a correlation between PLK1 expression and immune infiltration in LA.Silencing of PLK1 using miRNA transfection in LA cells reduced cell proliferation and increased apoptosis,as well as upregulating the expression of necroptosis-related proteins,such as RIPK1,RIPK3,and MLKL.Additionally,nude mouse transplantation tumor experiments demonstrated that silencing PLK1 reduced the growth capacity of LA cells.These findings suggest that PLK1 plays a critical role in LA progression by regulating necroptosis and immune infiltration,and may serve as a potential therapeutic target for immunotherapy.Furthermore,PLK1 expression can be used as a prognostic biomarker for LA patients.

Heritage Impact Assessment (HIA) as an Alternative Evaluation Tool for Historical Built Heritages in Lahore, Pakistan

Heritage Impact Assessments(HIAs)are progressively needed to investigate potential impacts and outcomes of development on the Outstanding Universal Value(OUV)of world heritage properties.However,many key stakeholders involved in implementing the World Heritage Convention lack the management system,methodological tools,and guidelines to conduct effective impact assessments in areas without these resources.The paper explores the successful utilization of the Heritage Impact Assessment(HIA)tool to address concerns raised by UNESCO and civil society.This occurred when the Punjab government initiated the Orange Line Metro Train Project(OLMT)near the World Heritage Shalimar Garden and other historic monuments in Lahore.The project aimed to meet the daily transportation needs of around 2.5 million commuters.

Numerical analysis of the three-dimensional aerodynamics of a hovering rufous hummingbird(Selasphorus rufus)

Hummingbirds have a unique way of hover- ing. However, only a few published papers have gone into details of the corresponding three-dimensional vortex struc- tures and transient aerodynamic forces. In order to deepen the understanding in these two realms, this article presents an integrated computational fluid dynamics study on the hovering aerodynamics of a rufous hummingbird. The original morphological and kinematic data came from a former researcher＇s experiments. We found that conical and sta- ble leading-edge vortices （LEVs） with spanwise flow inside their cores existed on the hovering hummingbird＇s wing surfaces. When the LEVs and other near-field vortices were all shed into the wake after stroke reversals, periodically shed bilateral vortex rings were formed. In addition, a strong downwash was present throughout the flapping cycle. Time histories of lift and drag were also obtained. Combining the three-dimensional flow field and time history of lift, we believe that high lift mechanisms （i.e., rotational circulation and wake capture） which take place at stroke reversals in insect flight was not evident here. For mean lift throughout a whole cycle, it is calculated to be 3.60 g （104.0 % of the weight support）. The downstroke and upstroke provide 64.2 % and 35.8 % of the weight support, respectively.

Comparisons between CRM and CCM PFC

The paper presents detailed comparisons between CRM (critical conduction mode) and CCM (continuous conduction mode) control schemes used for Boost PFC converter. The two schemes are analyzed and compared under the chips of L6561 and UC 3854 which are commonly used for CRM and CCM respectively. Both schemes are based on multiplier;however, the CCM is more complex and needs more periphery components which increase the cost. The Boost PFC under CRM is easier to be implemented. Nevertheless, the variable switch frequency makes the system (including the power-stage inductor and capacitor) hard to design. It seems that the CRM PFC is more attractive in low power applications which only need to meet IEC61000-3-2 D standard. Some experiment results are also presented for the comparison.

Unveiling chain–chain interactions in CO2-based crystalline stereocomplexed polycarbonates by solid-state NMR spectroscopy and DFT calculations

CO2-based stereocomplexed polycarbonates derived from the intermolecularly interlocked interaction between the enantiopure polymers with the opposite configuration exhibit high crystallinity, excellent thermal and mechanical stabilities. Deep insights into the mechanism of stereocomplexation are of particular importance to the design and manufacture of new promising and sustainable polycarbonates with enhanced physicochemical properties. Our solid-state NMR experiments linking with DFT computations clearly reveal the specific chain-chain interactions in a typical stereocomplexed poly（4,4-dimethyl-3,5,8-trioxabicyclo[5.1.0] octane carbonate）（PCXC）.13C CP/MAS NMR,1H DUMBO MAS NMR and 13C/1H relaxation-time measurements indicate that the formation of stereocomplex reduces the local mobilities of carbonyl, methine and methylene groups in each chain of PCXC significantly. Through a combination of two-dimensional 1H-13C HETCOR NMR and DFT calculation analysis, the cis-/trans-conformations and packing models of PCXC chains in the amorphous, enantionpure isotactic and stereocomplexed polycarbonates are identified. The splitting of 13C and 1H NMR chemical shifts of methine groups in the backbone carbon region demonstrates the ordered interlock interactions between the R-and S-chain in the stereocomplexed PCXC.

A Digital Controller Design Method to Improve Performance of PFC Converter

With the rapid development of digital signal processing chip in recent years, DSP began to be used in more switching power supply. The advantages of digital control of their own, making the digital control PFC become a hotspot research. However, compared with the simulation system, the digital control technology still has many problems. In this paper, the problem of digital PI compensator as a voltage compensator is discussed, and the Single-pole voltage loop compensator is used in digital control PFC circuit. Because current loop bandwidth is narrow, a method to expand current loop bandwidth is put forward. Output power 300 W of prototype is made, and experimental results verify the correctness of the theory.

Analysis and Modeling of Buck Converter in Discontinuous-Output-Inductor-Current Mode Operation

The Buck converter with LC input filter operating in discontinuous output current mode has a high power factor with a constant duty cycle. A Buck converter in this operation mode can reduce the reverse recovery loss of the freewheeling diode thus increase the efficiency. The operation, power factor analysis and modeling of the converter are studied in this paper. Experimental results are presented to verify the theoretical predictions.

A High Power Factor Rectifier Based on Buck Converter Operating in Discontinuous Inductor Current Mode

By adding a suitable LC filter to the input of a Buck converter, a high-power-factor buck converter is proposed. The converter can operate in the discontinuous-output-current mode operation. A Buck converter in this operation mode features simple control as the constant duty cycle PWM used. The operation condition of the converter is studied. The validity of analysis is verified by Simulation and Experimental results.

A Single Phase Current Source PFC Converter Based on UC3854

A novel high-power-factor Buck type converter with average current control based on UC 3854 is proposed. The input current is directly controlled by average current control scheme to deliver sinusoidal input current and to gain a high power factor. The practical results, which illustrate the proposed control philosophy, were obtained from a 120 W AC/DC Buck type converter. The power factor can reach 0.97.

Stochastic resonance of spinor condensates in optical cavity

Stochastic resonance is a phenomenon in which adding random noise to a system enhances the detection or transmission of a weak signal. It occurs when the noise interacts with the system's nonlinearity, thus improving signal-to-noise ratio and increasing sensitivity. Although parametric resonances in an atomic spinor Bose-Einstein condensate have been investigated, the question of whether one can observe stochastic resonance in such a system persists. In this study we propose a scheme for generating stochastic resonance in a cavity-spinor Bose-Einstein condensate coupling system. We demonstrate stochastic resonance through numerical calculations using the mean-field theory and truncated Wigner approximation methods. Furthermore, the characteristics of the system's response to noise and periodic signals are studied in detail. This study unravels a new scheme for observing stochastic resonance via linking atomic many-body physics with cavity quantum electrodynamics.

品管圈活动在提高超声医学科住院医师医疗质量中的作用

目的探讨品管圈活动在提高超声医学科住院医师医疗质量中的作用。方法2020年11月至2021年3月由南昌大学第一附属医院超声医学科8个亚专业组组长组成品管圈小组,应用品管圈管理方法对10名住院医师在医疗活动中存在的问题进行分析,制订相应措施及实施方案,采用方差分析比较品管圈活动实施前(2020年11月)、实施中(2020年12月,2021年1、2月)及实施后(2021年3月)住院医师的工作终质量的差异,各个月份之间两两比较采用Bonfermoi检验。结果实施品管圈活动后,住院医师的工作终质量有显著提高,各月之间差异具有统计学意义(F=135.047,P<0.001)。品管圈活动实施后的工作终质量评分高于实施前[(64.38±2.54)分vs(44.21±1.39)分],差异具有统计学意义(校正P<0.01);品管圈活动实施中各月(2020年12月,2021年1、2月)的工作终质量持续上升[(52.20±1.71)分vs(57.22±2.31)分vs(62.35±2.24)分],差异均具有统计学意义(校正P均<0.01);品管圈活动实施结束月(2021年2月)与实施后(2021年3月)的工作终质量[(62.35±2.24)分vs(64.38±2.54)分]比较,差异无统计学意义(P=0.345)。结论品管圈活动能有效提高住院医师工作终质量,改善医疗质量,提升住院医师的综合能力。

Optimal initial states for quantum parameter estimation based on Jaynes–Cummings model[Invited]

Quantum parameter estimation is a crucial tool for inferring unknown parameters in physical models from experimental data.The Jaynes–Cummings model is a widely used model in quantum optics that describes the interaction between an atom and a single-mode quantum optical field.In this Letter,we systematically investigate the problem of estimating the atom-light coupling strength in this model and optimize the initial state in the full Hilbert space.We compare the precision limits achievable for different optical field quantum states,including coherent states,amplitude-and phase-squeezed states,and provide experimental suggestions with an easily prepared substitute for the optimal state.Our results provide valuable insights into optimizing quantum parameter estimation in the Jaynes–Cummings model and can have practical implications for quantum metrology with hybrid quantum systems.

Optomechanical preparation of photon number-squeezed states with a pair of thermal reservoirs of opposite temperatures

Photon number-squeezed states are of significant value in fundamental quantum research and have a wide range of applications in quantum metrology.Most of their preparation mechanisms require precise control of quantum dynamics and are less tolerant to dissipation.We propose a mechanism that is not subject to these restraints.In contrast to common approaches,we exploit the self-balancing between two types of dissipation induced by positive-and negative-temperature reservoirs to generate steady states with sub-Poissonian statistical distributions of photon numbers.We also show how to implement this mechanism with cavity optomechanical systems.The quality of the prepared photon number-squeezed state is estimated by our theoretical model combined with realistic parameters for various typical optomechanical systems.

Investigation of the Rayleigh–Taylor instability in charged fluids

The present study shows that the Rayleigh–Taylor(RT)instability and its growth rate are strongly dependent on the charge-mass ratio of charged particles in a charged fluid.A higher charge-mass ratio of the charged fluid appears to result in a stronger effect of the magnetic field to suppress the RT instability.We study the RT instabilities for both dusty plasma(small chargemass ratio of charged particles)and ion-electron plasma(large charge-mass ratio of charged particles).It is found that the impact of the external magnetic field to suppress the RT instability for ion-electron plasma is much greater than that for dusty plasma.It is also shown that,for a dusty plasma,in addition to region parameters such as the external magnetic field,region length,its gradient,as well as dust particle parameters such as number density,mass,and charge of dust particles,the growth rate of the RT instability in a dusty plasma also depends on parameters of both electrons and ions such as the number densities and temperatures of both electrons and ions.

时序相依数据的一种基于约束Cholesky分解的简约Gauss copula建模方法

对具有时序相依性的离散数据,本文从隐变量的角度使用Gauss copula建模.不同于现有方法,本文对协方差提出一种新的约束以实现Gauss copula模型的可识别性,并基于此提出一个新的隐变量框架对隐Gauss变量的方差和协方差进行简约建模,从而将基于修正的Cholesky分解的联合建模方法推广到广义线性模型中,建立相应的理论性质.模拟和实际数据分析验证了所提出方法的性能.

Identification and functional analysis of the MOC1 interacting protein 1

Rice tillering is one of the most important agronomic traits that determine grain yields.Our previous study has demonstrated that the MONOCULM1 （MOC1） gene is a key component that controls the formation of rice tiller buds.To further elucidate the molecular mechanism of MOC1 involved in the regulation of rice tillering,we performed a yeast-two-hybrid screening to identify MOC1 interacting proteins （MIPs）.Here we reported that MIP1 interacted with MOC1 both in vitro and in vivo.The overexpression of MIP1 resulted in enhanced tillering and reduced plant height.In-depth characterization of the context of MIP1 and MOC1 would further our understanding of molecular regulatory mechanisms of rice tillering.

INTERCROPPING:FEED MORE PEOPLE AND BUILD MORE SUSTAINABLE AGROECOSYSTEMS

Intercropping is a traditional farming system that increases crop diversity to strengthen agroecosystem functions while decreasing chemical inputs and minimizing negative environmental effects of crop production.Intercropping is currently considerable interest because of its importance in sustainable agriculture.Here,we synthesize the factors that make intercropping a sustainable means of food production by integrating biodiversity of natural ecosystems and crop diversity.In addition to well-known yield increases,intercropping can also increase yield stability over the long term and increase systemic resistance to plant diseases,pests and other unfavorable factors(e.g.,nutrient deficiencies).The efficient use of resources can save mineral fertilizer inputs,reduce environmental pollution risks and greenhouse gas emissions caused by agriculture,thus mitigating global climate change.Intercropping potentially increases above-and belowground biodiversity of various taxa at field scale,consequently it enhances ecosystem services.Complementarity and selection effects allow a better understanding the mechanisms behind enhanced ecosystem functioning.The development of mechanization is essential for largescale application of intercropping.Agroecosystem multifunctionality and soil health should be priority topics in future research on intercropping.

A Sub-100 mg Electromagnetically Driven Insect-inspired Flapping-wing Micro Robot Capable of Liftoff and Control Torques Modulation

Inspired by the unique,agile and efficient flapping flight of insects,we present a novel sub-100 mg,electromagnetically driven,tailless,flapping-wing micro robot.This robot utilizes two optimized electromagnetic actuators placed back to back to drive two wings separately,then kinematics of each wing can be independently controlled,which gives the robot the ability to generate all three control torques of pitch,roll and yaw for steering.To quantify the performance of the robot,a simplified aerodynamic model is used to estimate the generated lift and torques,and two customized test platforms for lift and torque measurement are built for this robot.The mean lift generated by the robot is measured to be proportional to the square of the input voltage amplitude.The three control torques are measured to be respectively proportional to three decoupled parameters of the control voltages,therefore the modulation of three control torques for the robot is independent,which is helpful for the further controlled flight.All these measured results fit well with the calculated results of the aerodynamic model.Furthermore,with a total weight of 96 mg and a wingspan of 3.5 cm,this robot can generate sufficient lift to take off.