推荐一个无机合成综合实验——基于废弃大豆油的微乳液法制备纳米氧化锌

纳米氧化锌是一类多功能纳米材料,由于其优秀的物理化学性质而被广泛应用于多个领域。传统的合成方法存在成本过高、过程复杂、产物不稳定等问题。微乳合成法具有操作简单,成本低廉,产物尺寸可控等优点,可以有效避免传统合成方法的缺陷。特别是将废弃大豆油合成的乳化剂应用在合成的过程中,可以实现废物的回收再利用,又能满足绿色化学和可持续发展的要求。使用X射线衍射(XRD)、扫描电镜(SEM)、化学分析等多种方法对产物纳米氧化锌的形貌和性质进行了表征,实现了无机合成-化学分析-仪器分析的综合偶联,从而达到提升大学生进行综合实验能力的目的。

Discussion on the Homology Theory of Lie Algebras

Because homology on compact homogeneous nilpotent manifolds is closely related to homology on Lie algebras, studying homology on Lie algebras is helpful for further studying homology on compact homogeneous nilpotent manifolds. So we start with the differential sequence of Lie algebras. The Lie algebra g has the differential sequence E0,E1,⋯,Es⋯, which leads to the chain complex Es0→Δs0Ess→Δs1⋯→ΔsiEs(i+1)s→Δsi+1⋯of Esby discussing the chain complex E10→Δ10E11→Δ11⋯→Δ1r−1E1r→Δ1r⋯of E1and proves that Es+1i≅Hi(Es)=KerΔsi+1/ImΔsiand therefore Es+1≅H(Es)by the chain complex of Es(see Theorem 2).

The Study of Root Subspace Decomposition between Characteristic Polynomials and Minimum Polynomial

Let Abe the linear transformation on the linear space V in the field P, Vλibe the root subspace corresponding to the characteristic polynomial of the eigenvalue λi, and Wλibe the root subspace corresponding to the minimum polynomial of λi. Consider the problem of whether Vλiand Wλiare equal under the condition that the characteristic polynomial of Ahas the same eigenvalue as the minimum polynomial (see Theorem 1, 2). This article uses the method of mutual inclusion to prove that Vλi=Wλi. Compared to previous studies and proofs, the results of this research can be directly cited in related works. For instance, they can be directly cited in Daoji Meng’s book “Introduction to Differential Geometry.”

发现驱动中医药研究的新范式

发挥中医药原创优势、推动我国生命科学实现创新突破是国家需求,但如何挖掘中医药的原创优势,还需要进一步提升思想认知,用现代科学解读中医药学原理。本文在建国以来中医药实证性研究的基础上,正本清源,传承精华,厘清中医学中未加工事实与理性推演之间的关系,发现其中的科学事实;阐幽明微,守正创新,应用现代科学技术,发现中医理论与效应的独特原创优势,从中医出发为医学与生命科学做贡献,解决生物医药“卡脖子”问题两方面,面向未来,列举例证,发现驱动中医药研究的新范式:在厘清古籍医学事实、明确中医药临床效应的基础上,深入研究中国医学中尚不能被现代医学解释的独特生物学现象和过程,以期揭示新的生理现象、阐释新的病理机制、创建新的治疗策略,更加充分地发挥中医药原创优势,推动我国生物医学实现创新突破。

CRISPR/Cas9系统在畜禽遗传改良中研究进展

CRISPR/Cas9基因编辑技术作为一种高效的基因组编辑方法,在畜牧业遗传改良领域得到了广泛的应用。该技术以高效、精准的特点,为畜牧业发展带来了一场革命。目前,基于CRISPR/Cas9的基因敲除、基因敲入和基因修饰等已被广泛应用,实现了对畜禽物种的重要生产性状进行精准改良。本文介绍了CRISPR/Cas9技术的工作原理及发展历程,重点介绍了该技术在畜禽肌肉生长发育、绒毛纤维生长、乳品质成分、抗病育种以及动物福利中的研究进展,旨在为更深入地了解CRISPR/Cas9技术在畜禽基因编辑上的应用提供参考。

肺部切除术后慢性咳嗽预测模型的建立与验证

背景与目的肺部切除术后慢性咳嗽是最常见的并发症之一,严重影响患者术后生活质量,目前国内尚无关于肺部切除术后慢性咳嗽预测模型。因此,本研究旨在探讨肺部切除术后慢性咳嗽相关危险因素,构建预测模型并进行验证。方法回顾性分析2021年1月至2023年6月于中国科学技术大学附属第一医院接受肺部切除术的499例患者的临床资料和术后咳嗽情况,按7:3随机分配原则分为训练集(n=348)和验证集(n=151),根据训练集患者术后是否慢性咳嗽分为咳嗽组和非咳嗽组。使用中文版莱斯特咳嗽问卷(The Mandarin-Chinese version of Leicester cough questionnare,LCQ-MC)评估术前、术后咳嗽的严重程度及其对患者生活质量的影响,采用咳嗽视觉模拟量表(visual analog scale,VAS)和自拟的数字评分法(numerical rating scale,NRS)评估术后慢性咳嗽,采用单因素和多因素Logistic回归分析独立危险因素和模型构建,受试者工作特征(receiver operator characteristic,ROC)曲线评估模型区分度,校准曲线评估模型的一致性,绘制决策曲线分析(decision curve analysis,DCA)评估模型的临床应用价值。结果多因素Logistic分析筛选出术前用力呼气第1秒呼气量与用力肺活量比(forced expiratory volume in the first second/forced vital capacity,FEV_(1)/FVC)、手术方式、行上纵隔淋巴结清扫、行隆突下淋巴结清扫、术后胸腔闭式引流时间是术后慢性咳嗽的独立危险因素,基于多因素分析结果构建列线图预测模型。ROC曲线下面积为0.954(95%CI:0.930-0.978),最大约登指数所对应的临界值为0.171,此时敏感度为94.7%,特异度为86.6%。Bootstrap法抽样1000次,校准曲线图预测的肺部切除术后慢性咳嗽与实际发生风险高度一致。DCA显示当预测模型概率的预概率为0.1-0.9之间,患者表现为正的净收益。结论肺部切除术后慢性咳嗽严重影响患者生活质量。列线图的可视化展现形式有助于准确预测肺部切除术后慢性咳嗽,为临床决策提供支持。

Cr涂层对Zr-4合金蠕变行为的影响

报道化学气相沉积Cr涂层对Zr-4合金蠕变性能的影响以及Cr涂层在服役温度下的热稳定性。利用扫描电镜、电子探针显微分析和电子背散射衍射研究样品的显微组织。结果表明:样品Zr-4基体中晶粒呈等轴状,存在明显的<0001>//ND织构。蠕变后涂层样品的Zr-4合金基体中亚晶界数量明显低于无涂层样品Zr-4合金基体中亚晶界数量,表明Cr涂层显著降低了Zr-4合金基体在蠕变过程中承载的应力,提高了合金的抗蠕变性能。Cr涂层在长时间扩散实验中保持高稳定性。涂层在高蠕变应力下(350℃时不小于157 MPa,400℃时不小于137 MPa)出现裂纹。系统总结蠕变断裂的数据,得到了关于稳态蠕变速率与蠕变断裂时间的Monkman-Grant关系式。

两种麻纤维育秧膜对水稻秧苗根际土壤微生物群落结构的影响

试验主要探究了壳寡糖麻育秧膜和普通麻育秧膜对水稻秧苗根际土壤理化性质和微生物群落结构的影响。结果表明:使用两种不同麻育秧膜组中土壤pH、总氮含量增加;普通麻育秧膜处理下土壤有机质显著降低;壳寡糖麻育秧膜处理下总钾含量显著降低。与无膜覆盖的对照组相比,两种不同麻育秧膜处理下水稻秧苗根际土壤真菌多样性并没有显著变化,而细菌的多样性和丰富度显著降低。对根际土壤理化性质和土壤微生物群落进行冗余分析,发现水解氮与根际土壤真菌群落的相关性最大,而土壤有机质则与根际土壤细菌群落分布的相关性最大。

可降解地膜对大棚内土壤温湿度和草莓产量及品质的影响初探

冬季大棚草莓种植常用地膜覆盖,塑料残膜危害严重,试验以塑料地膜为对照,研究两种PBAT地膜(PBAT地膜1、PBAT地膜2)和一种环保型麻地膜对大棚内土壤温湿度和草莓产量及品质的影响,验证可降解地膜在草莓种植中应用的可行性。结果表明:PBAT地膜1草莓苗穴处温湿度较高,麻地膜膜下湿度最低;可降解地膜早期开花率和结果率高于塑料地膜;PBAT地膜1和麻地膜栽培的草莓早期产量显著高于塑料地膜,分别高出33.37%和22.98%,草莓总产量各处理间无显著差异;结果盛期各处理的草莓甜度和硬度无显著差异,塑料地膜、PBAT地膜1和麻地膜草莓单果重更高。试验初步表明,PBAT地膜和麻地膜可以用于冬季大棚草莓种植,其中PBAT地膜1和麻地膜效果最优。

H_(2)O及其中间体在缺电子Mn^((3+δ)+)位的自发增强吸附及其促进光催化产H_(2)O_(2)性能

过渡金属羟基氧化物已被证明是水氧化反应的可靠助催化剂。然而,在水氧化过程中它们对H_(2)O及其中间产物的吸附能力不足,极大制约了水氧化速率的提高。在本研究中,H_(2)O及其中间体在MnOOH助剂的缺电子Mn^((3+δ)+)上的自发增强吸附可以极大地促进水的快速氧化,从而在纯水体系中实现高效的光催化H_(2)O_(2)生成。首先,无定形MnOOH通过定向光诱导氧化方法选择性地沉积在AuPd改性的单晶BiVO_(4)光催化剂的(110)面上,从而制备了AuPd/BiVO_(4)/MnOOH光催化剂。光催化实验表明,所制备的AuPd/BiVO_(4)/MnOOH(0.5%)光催化剂的H_(2)O_(2)产生速率达到214μmol·L^(-1),并表现出良好的稳定性和重现性。密度泛函理论计算和X射线光电子能谱表征表明,MnOOH的自由电子可以有效地转移到BiVO_(4)上,诱导缺电子Mn位(Mn^((3+δ)+))的产生,从而自发地促进H_(2)O及其中间体的吸附,增强四电子WOR反应,导致H_(2)O_(2)的高效生成。本文关于助催化剂与主体催化剂之间强相互作用的工作为其它高效催化材料的合理设计提供了一种新的思路。

Tuning electronic structure of RuO_(2)by single atom Zn and oxygen vacancies to boost oxygen evolution reaction in acidic medium

The poor stability of RuO_(2)electrocatalysts has been the primary obstacles for their practical application in polymer electrolyte membrane electrolyzers.To dramatically enhance the durability of RuO_(2)to construct activity-stability trade-off model is full of significance but challenging.Herein,a single atom Zn stabilized RuO_(2)with enriched oxygen vacancies(SA Zn-RuO_(2))is developed as a promising alternative to iridium oxide for acidic oxygen evolution reaction(OER).Compared with commercial RuO_(2),the enhanced Ru–O bond strength of SA Zn-RuO_(2)by forming Zn-O-Ru local structure motif is favorable to stabilize surface Ru,while the electrons transferred from Zn single atoms to adjacent Ru atoms protects the Ru active sites from overoxidation.Simultaneously,the optimized surrounding electronic structure of Ru sites in SA ZnRuO_(2)decreases the adsorption energies of OER intermediates to reduce the reaction barrier.As a result,the representative SA Zn-RuO_(2)exhibits a low overpotential of 210 mV to achieve 10 mA cm^(-2)and a greatly enhanced durability than commercial RuO_(2).This work provides a promising dual-engineering strategy by coupling single atom doping and vacancy for the tradeoff of high activity and catalytic stability toward acidic OER.

A dual-RPA based lateral flow strip for sensitive,on-site detection of CP4-EPSPS and Cry1Ab/Ac genes in genetically modified crops

Traditional transgenic detection methods require high test conditions and struggle to be both sensitive and efficient.In this study,a one-tube dual recombinase polymerase amplification(RPA)reaction system for CP4-EPSPS and Cry1Ab/Ac was proposed and combined with a lateral flow immunochromatographic assay,named“Dual-RPA-LFD”,to visualize the dual detection of genetically modified(GM)crops.In which,the herbicide tolerance gene CP4-EPSPS and the insect resistance gene Cry1Ab/Ac were selected as targets taking into account the current status of the most widespread application of insect resistance and herbicide tolerance traits and their stacked traits.Gradient diluted plasmids,transgenic standards,and actual samples were used as templates to conduct sensitivity,specificity,and practicality assays,respectively.The constructed method achieved the visual detection of plasmid at levels as low as 100 copies,demonstrating its high sensitivity.In addition,good applicability to transgenic samples was observed,with no cross-interference between two test lines and no influence from other genes.In conclusion,this strategy achieved the expected purpose of simultaneous detection of the two popular targets in GM crops within 20 min at 37°C in a rapid,equipmentfree field manner,providing a new alternative for rapid screening for transgenic assays in the field.

Effect of electrical parameters and slag system on macrostructure of electroslag ingot

To investigate the influence of electric parameters and slag system on the solidification quality of electroslag ingot during electroslag remelting,different power supply modes,current strengths and remelting slag systems were used to conduct electroslag remelting experiments on 304L austenitic stainless steel,and the macrostructure of electroslag ingots was analyzed.The results indicate that the depth of the metal pool decreases with the reduction of remelting frequency in the low frequency power supply mode.The effects of different power supply modes,such as low-frequency,direct current straight polarity(DCSP),and direct current reverse polarity(DCRP),on reducing the depth of the metal pool increase in that order.By reducing the remelting current strength in the same power supply mode,the depth of metal pool is reduced.When compared to the binary slag system of 70%CaF2+30%Al2O3,the ternary slag system of 60%CaF2+20%Al2O3+20%CaO is more effective in reducing the depth of the metal pool during remelting.Utilizing the 60%CaF2+20%Al2O3+20%CaO ternary slag system results in a shallower and flatter metal pool,with columnar crystal growth occurring closer to the axial crystal.This effect is observed for both low frequency and direct current(DC)power supply modes.

Identification of the lysine and histidine transporter family in Camellia sinensis and the characterizations in nitrogen utilization

In plants,the lysine and histidine transporter(LHT)family represent a class of proteins that mediate the uptake,translocation,and utilization of amino acids.The tea plant(Camellia sinensis)is a perennial evergreen with a relatively high level of amino acids.However,systematic identification and molecular characterization of the LHT gene family has rarely been reported in tea plants.In this study,22 CsLHTs were identified from the‘Shuchazao’genome and classified into two groups.The modeled three-dimensional structure and the conserved domains presented a high similarity among the LHTs proteins.Moreover,it was predicted that a few genes were conserved through the analysis of the physiochemical characters,structures and cis-elements in promoters.The expression patterns in tea plants revealed that CsLHT7 was mainly expressed in the roots,and CsLHT4 and CsLHT11 exhibited relatively high expression in both the roots and leaves.Moreover,the expression of all three genes could be induced by organic nitrogen.Additionally,heterogeneous expression of CsLHT4,CsLHT7 and CsLHT11 in Arabidopsis thaliana decreased the aerial parts biomass compared with that in WT plants while significantly increased the rosette biomass only for CsLHT11transgenic plants versus WT plants.Overall,our results provide fundamental information about CsLHTs and potential genes in N utilization for further analysis in tea plants.

In vivo imaging of the neuronal response to spinal cord injury:a narrative review

Deciphering the neuronal response to injury in the spinal cord is essential for exploring treatment strategies for spinal cord injury(SCI).However,this subject has been neglected in part because appropriate tools are lacking.Emerging in vivo imaging and labeling methods offer great potential for observing dynamic neural processes in the central nervous system in conditions of health and disease.This review first discusses in vivo imaging of the mouse spinal cord with a focus on the latest imaging techniques,and then analyzes the dynamic biological response of spinal cord sensory and motor neurons to SCI.We then summarize and compare the techniques behind these studies and clarify the advantages of in vivo imaging compared with traditional neuroscience examinations.Finally,we identify the challenges and possible solutions for spinal cord neuron imaging.

Hypoxia-preconditioned bone marrow-derived mesenchymal stem cells protect neurons from cardiac arrest-induced pyroptosis

Cardiac arrest can lead to severe neurological impairment as a result of inflammation,mitochondrial dysfunction,and post-cardiopulmonary resuscitation neurological damage.Hypoxic preconditioning has been shown to improve migration and survival of bone marrow–derived mesenchymal stem cells and reduce pyroptosis after cardiac arrest,but the specific mechanisms by which hypoxia-preconditioned bone marrow–derived mesenchymal stem cells protect against brain injury after cardiac arrest are unknown.To this end,we established an in vitro co-culture model of bone marrow–derived mesenchymal stem cells and oxygen–glucose deprived primary neurons and found that hypoxic preconditioning enhanced the protective effect of bone marrow stromal stem cells against neuronal pyroptosis,possibly through inhibition of the MAPK and nuclear factor κB pathways.Subsequently,we transplanted hypoxia-preconditioned bone marrow–derived mesenchymal stem cells into the lateral ventricle after the return of spontaneous circulation in an 8-minute cardiac arrest rat model induced by asphyxia.The results showed that hypoxia-preconditioned bone marrow–derived mesenchymal stem cells significantly reduced cardiac arrest–induced neuronal pyroptosis,oxidative stress,and mitochondrial damage,whereas knockdown of the liver isoform of phosphofructokinase in bone marrow–derived mesenchymal stem cells inhibited these effects.To conclude,hypoxia-preconditioned bone marrow–derived mesenchymal stem cells offer a promising therapeutic approach for neuronal injury following cardiac arrest,and their beneficial effects are potentially associated with increased expression of the liver isoform of phosphofructokinase following hypoxic preconditioning.

Correlation between the rock mass properties and maximum horizontal stress:A case study of overcoring stress measurements

Understanding the mechanical properties of the lithologies is crucial to accurately determine the horizontal stress magnitude.To investigate the correlation between the rock mass properties and maximum horizontal stress,the three-dimensional(3D)stress tensors at 89 measuring points determined using an improved overcoring technique in nine mines in China were adopted,a newly defined characteristic parameter C_(ERP)was proposed as an indicator for evaluating the structural properties of rock masses,and a fuzzy relation matrix was established using the information distribution method.The results indicate that both the vertical stress and horizontal stress exhibit a good linear growth relationship with depth.There is no remarkable correlation between the elastic modulus,Poisson's ratio and depth,and the distribution of data points is scattered and messy.Moreover,there is no obvious relationship between the rock quality designation(RQD)and depth.The maximum horizontal stress σ_(H) is a function of rock properties,showing a certain linear relationship with the C_(ERP)at the same depth.In addition,the overall change trend of σ_(H) determined by the established fuzzy identification method is to increase with the increase of C_(ERP).The fuzzy identification method also demonstrates a relatively detailed local relationship betweenσ_H and C_(ERP),and the predicted curve rises in a fluctuating way,which is in accord well with the measured stress data.

A guidance and control design with reduced information for a dual-spin stabilized projectile

In this paper,an integrated guidance and control method based on an adaptive path-following controller is proposed to control a spin-stabilized projectile with only translational motion information under the constraint of an actuator,uncertainties in aerodynamic parameters and measurements,and control system complexity.Owing to the fairly high rotation speed,the dynamic model of this missile is strongly nonlinear,uncertain and coupled in pitch,yaw and roll channels.A theoretical equivalent resultant force and uncertainty compensation method are comprehensively used to realize decoupling of pitch and yaw.In response to the strong nonlinear and time-varying characteristics of the dynamic system,the quasi-linear model whose parameters are obtained by interpolation of points selected as the segmentation points in the trajectory envelope,is used for calculation in each step.To cope with the system uncertainty caused by model approximation,parameter uncertainty and ballistic interference,an extended state estimator is used to compensate the output feedback according to the test ballistic angle.In order to improve the tracking efficiency and ensure the tracking error convergence with only translational motion information,the virtual guide point,whose derivative is deduced according to the Lyapunov principle,is calculated in real time according to the projection relationship between the real-time position and the reference trajectory,and a virtual line-of-sight angle and the backstepping method are used for the design of the guidance and control system.In order to avoid the influence of control input saturation on the guidance and control performance due to the actuator limitation and improve the robustness of the system,an anti-saturation compensator is designed according to the two-step method.The feasibility and effectiveness of the path-following controller is verified through closed-loop flight simulations with measurement,control,and condition uncertainties.The results indicate that the designed controller can converge to the reference path and evidently decrease the distance between the impact point and target under different uncertainties.

A low-profile metamaterial absorber with ultrawideband reflectionless and wide-angular stability

An ultrawideband reflectionless metamaterial absorber(MA)is proposed by replacing the metallic ground with the complementary split-ring resonator(CSRR)structure.The proposed MA exhibits-10 d B reflectivity spectrum from 1 GHz to 20 GHz,which maintains more than 90%absorption from 1.5 GHz to20 GHz.Furthermore,it achieves angle stability for TE and TM polarization at oblique incident angles up to 40°and 65°,respectively.To achieve broadband absorption spectrum,we have adopted a single-layer high-impedance surface(HIS)loaded with a double-layer magnetic material(MM)structure.To further realize the RCS reduction into a lower frequency range,we have employed the scattering cancellation technology into the traditional metallic ground.Finally,we have fabricated a sample exhibiting the 10 d B RCS reduction from 1 GHz to 20 GHz with a thickness of 10 mm.Measurement and simulation results confirm that the proposed MA exhibits excellent comprehensive performance,making it suitable for many practical applications.

Optimized parameters of downhole all-metal PDM based on genetic algorithm

Currently,deep drilling operates under extreme conditions of high temperature and high pressure,demanding more from subterranean power motors.The all-metal positive displacement motor,known for its robust performance,is a critical choice for such drilling.The dimensions of the PDM are crucial for its performance output.To enhance this,optimization of the motor's profile using a genetic algorithm has been undertaken.The design process begins with the computation of the initial stator and rotor curves based on the equations for a screw cycloid.These curves are then refined using the least squares method for a precise fit.Following this,the PDM's mathematical model is optimized,and motor friction is assessed.The genetic algorithm process involves encoding variations and managing crossovers to optimize objective functions,including the isometric radius coefficient,eccentricity distance parameter,overflow area,and maximum slip speed.This optimization yields the ideal profile parameters that enhance the motor's output.Comparative analyses of the initial and optimized output characteristics were conducted,focusing on the effects of the isometric radius coefficient and overflow area on the motor's performance.Results indicate that the optimized motor's overflow area increased by 6.9%,while its rotational speed reduced by 6.58%.The torque,as tested by Infocus,saw substantial improvements of38.8%.This optimization provides a theoretical foundation for improving the output characteristics of allmetal PDMs and supports the ongoing development and research of PDM technology.