在大学物理教学中培养学生的批判性思维能力--浅析开放性提问的作用

具有独立思考和批判性思维能力对于提高创新能力具有重要作用,但目前大学普通物理教学还侧重于知识的传授,缺少对学生批判性思维能力的培养和重视.本文从开放性提问的角度出发,阐述了如何在大学物理教学中培养学生独立思考的习惯和批判性思维的能力.文章举例分析了在科学历史、课程习题、演示实验和工程案例中挖掘开放性问题,通过以学为中心的课堂问答,激发学生学习热情和兴趣,增强课程的探索性和趣味性,从而达到提高学生批判思维能力的目的.     

Coagulation behaviors and in-situ flocs characteristics of composite coagulants in cyanide-containing wastewater: Role of cationic polyelectrolyte

In this paper,composite coagulants(PFS,PFSC05,PFSC1 and PFSC5),prepared by mixing polyferric sulfate(PFS)and cationic polyelectrolyte(CP)coagulants with different weight percent(Wp)of CP(Wp=0%,0.5%,1%and 5%,respectively),were adopted to treat cyanide-containing wastewater.PFSC5 exhibited superior coagulation performances at optimal conditions:the removal of total cyanide(TCN)and chemical oxygen demand(COD)was 95%–97%and 50%–55%,respectively.The effects of CP on the properties and structure of flocs were investigated by laser diffraction instrument and small-angle laser light scattering(SALLS),respectively.The results show that the flocs of PFSC5 have higher growth rate,higher strength factor and lower recovery factor than other flocs.They are also much denser and more uniform owing to the higher fractal dimension(Df)and less microflocs(10–100 m).Furthermore,the dense structure of the PFSC5 flocs can be restored after shear and is more resistant to hydraulic conditions.Particularly,detailed morphology evolution of the flocs was in-situ detected by on-line particle imaging.Due to strong ionic strength in wastewater,the CP in PFSC5 plays a significant role of adsorption,while the main mechanism of CP is electrostatic patch aggregation during the PFSC05 systems.     

Modeling of highly efficient drug delivery system induced by self-assembly of nanocarriers: A density functional study

Owing to the importance of drug delivery in cancer or other diseases’ therapy, the targeted drug delivery (TDD) system has been attracting enormous interest. Herein, we model the TDD system and design a novel rod-like nanocarrier by using the coarse grained model-based density functional theory, which combines a modified fundamental measure theory for the excluded-volume effects, Wertheim’s first-order thermodynamics perturbation theory for the chain connectivity and the mean field approximation for van der Waals attraction. For comparison, the monomer nanocarrier TDD system and the no nanocarrier one are also investigated. The results indicate that the drug delivery capacity of rod-like nanocarriers is about 62 times that of the no nanocarrier one, and about 6 times that of the monomer nanocarriers. The reason is that the rod-like nanocarriers would self-assemble into the smectic phase perpendicular to the membrane surface. It is the self-assembly of the rod-like nanocarriers that yields the driving force for the targeted delivery of drugs inside the cell membrane. By contrast, the conventional monomer nanocarrier drug delivery system lacks the driving force to deliver the drugs into the cell membrane. In short, the novel rod-like nanocarrier TDD system may improve the drug delivery efficiency. Although the model in this work is simple, it is expected that the system may provide a new perspective for cancer targeted therapy.     

S空位调节扶手型二硫化钼纳米带的电子性质

二硫化钼纳米带按边界结构特征可分为锯齿型和扶手型,在制备过程中,不可避免地会存在一定的缺陷,其中硫空位(VS)最为常见,它将改变纳米结构,进而影响其电子性质。本文采用密度泛函理论来研究S空位对扶手型二硫化钼纳米带性质的影响。计算结果表明：纯扶手型二硫化钼纳米带（AMoS2NRs）为非磁性半导体,但其物性受S空位的位置及浓度所调制。当S空位出现在纳米带内部时,其性质不变。但当S空位在纳米带边缘时,AMoS2NRs被调节成半金属;并随着S空位的浓度的增加,其物性从半金属转变为稀磁半导体。这一有趣的发现将使得低维MoS2纳米材料在自旋电子学上有更宽广的应用。     

Pure single line oscillation of HF lasers in fine atmospheric window

Applied Physics B - A correction to this paper has been published: https://doi.org/10.1007/s00340-021-07611-y     

A new three‐dimensional silver(I) coordination framework with a diamondoid topology constructed from 2‐(pyridin‐4‐yl)‐1H‐imidazole‐4,5‐dicarboxylic acid

The title compound, poly[[μ₄‐5‐carboxy‐4‐carboxylato‐2‐(pyridin‐4‐yl)‐1H‐imidazol‐1‐ido]disilver(I)], [Ag₂(C₁₀H₅N₃O₄)]_n, was synthesized by reacting silver nitrate with 2‐(pyridin‐4‐yl)‐1H‐imidazole‐4,5‐dicarboxylic acid (H₃PyIDC) under hydrothermal conditions. The asymmetric unit contains two crystallographically independent Ag^I cations and one unique HPyIDC²⁻ anion. Both Ag^I cations are three‐coordinated in distorted T‐shaped coordination geometries. One Ag^I cation is coordinated by one N and two O atoms from two HPyIDC²⁻ anions, while the other is bonded to one O and two N atoms from two HPyIDC²⁻ anions. It is interesting to note that the HPyIDC²⁻ group acts as a μ₄‐bridging ligand to link the Ag^I cations into a three‐dimensional framework, which can be simplified as a diamondoid topology. The thermal stability and photoluminescent properties of the title compound have also been studied.     

不同翅片单元外颗粒流换热特性的数值研究

由于成本低,运行稳定,重力驱动移动床在高温固体散料余热回收领域应用潜力较大。然而,相关强化传热技术目前仍待完善。本文基于离散单元法,对颗粒流外掠翅片单元的流动换热特性进行了数值研究。研究表明:通过翅片增加换热面,可以显著提高传热量,但不同翅片单元外颗粒流传热特性不同。颗粒流与不同表面的换热,由颗粒更新、颗粒接触、颗粒竞争掺混以及表面面积共同决定。总体来说,在迎流区,倾斜平表面能扩大面积并确保颗粒更新,更有利于换热增强。而对于背流区,竞争掺混与颗粒接触的影响更大,采用圆弧表面更有优势。