以培养自我调节学习能力为导向的分析化学实验混合教学模式

为探索合适的教学模式以培养自我调节学习为基础的终身学习能力,在分析化学实验的教学中,将学生按班级分为实验组和对照组,实验组采用了以“设计布鲁姆认知教育目标、融合翻转课堂模式和问题导向教学”等为主线的混合教学模式,对照组依然采用传统教学模式,最后根据访谈、教学平台留言和统一的测验题等方式评价教学效果。结果表明混合教学模式的教学效果优于传统教学,且实验组所有学生都愿意继续接受这种新的教学模式。教学实践证明,学生在制定自身学习目标及建立相应的自我调节学习策略方面有明显的改进。

SiC/Pt/CdS纳米棒Z型异质结的制备及其高效光催化产氢性能

本文采用简单的化学还原辅助水热法制备了一种新型Si C/Pt/Cd SZ型异质结纳米棒,并将Pt纳米粒子锚定在Si C纳米棒与Cd S纳米粒子的界面间,诱导电子-空穴对沿着Z型迁移路径进行转移。进行一系列的表征来分析该催化体系的结构,形貌和性能。X射线衍射(XRD)和X射线光电子能谱(XPS)结果表明,成功合成了具有较好晶体结构的光催化剂。通过透射电子显微镜证明,Pt纳米颗粒生长在Si C纳米棒和Cd S纳米颗粒的界面间。UV-Vis漫反射光谱显示,所制备的Z-型异质结样品具有比原始Cd S材料更宽的光吸收范围。光致发光光谱和瞬态光电流响应进一步证明具有最佳摩尔比的Si C/Pt/Cd S纳米棒样品具有最高的电子-空穴对分离效率。通过控制Si C和Cd S的摩尔比,可以有效地调节Si C/Pt纳米棒表面Cd S的负载量,从而使得Si C/Pt/Cd S纳米棒光催化剂达到最佳性能。当Si C:Cd S=5:1(摩尔比)时可以达到最佳产氢性能,其最大析氢速率达到122.3μmol·h-1。此外,从扫描电子显微镜、XRD和XPS分析可以看出,经过三次循环测试后,Si C/Pt/Cd S光催化剂的形貌和晶体结构均基本保持不变,表明Si C/Pt/Cd S纳米复合材料在可见光下产氢时具有稳定的结构。通过选择性光沉积技术在光反应中同时进行Au纳米粒子的光还原沉积和Mn3O4纳米粒子光氧化沉积以证明电子-空穴对的Z-型转移机制。实验结果表明,Cd S导带上的电子主要参与光催化过程中的还原反应,Si C价带上的空穴更容易发生氧化反应,其中,Si C的导带上的电子将与Cd S价带上的空穴复合形成Z型传输路径。因此,提出了在光催化产氢过程中Si C/Pt/Cd S纳米棒催化体系可能的Z-型电荷迁移路径来解释产氢活性的提高。该研究为基于Si C纳米棒的Z-型光催化体系的合成提供了新的策略。基于以上分析,Si C/Pt/Cd S纳米复合材料具有高效、廉价、易于制备、结构稳定等优势,具有突出的商业应用前景。

新型BiOI/g-C_3N_4纳米片复合光催化剂的制备及其可见光催化活性增强（英文）

近年来,石墨型氮化碳(g-C_3N_4)作为一种n型半导体光催化剂材料,由于具有较好的热稳定性和化学稳定性,同时具有可调的带隙结构和优异的表面性质而备受人们关注.然而,传统的g-C_3N_4块体材料存在比表面积小、光响应范围窄和光生载流子易复合等缺陷,制约着其光催化活性的进一步提高.因此,人们开发了多种技术对块体状g-C_3N_4材料进行改性,其中构建基于g-C_3N_4纳米薄片的异质结复合光催化材料被认为是强化g-C_3N_4载流子分离效率,进而提高其可见光催化活性的重要手段.BiOI作为一种窄带隙的p型半导体光催化剂,具有强的可见光吸收能力和较高的光催化活性,同时它与g-C_3N_4纳米薄片具有能级匹配的带隙结构.因此,基于以上两种半导体材料的特性,构建新型的BiOI/g-C_3N_4纳米片复合光催化剂材料不仅能够有效提高g-C_3N_4的可见光利用率,而且还可以在n型g-C_3N_4和p型BiOI界面间形成内建电场,极大促进光生电子-空穴对的分离与迁移效率.为此,本文通过简单的一步溶剂热法在g-C_3N_4纳米薄片表面原位生长BiOI纳米片材料,成功制备了新型的BiOI/g-C_3N_4纳米片复合光催化剂.利用X射线衍射仪(XRD),场发射扫描电子显微镜(SEM)、透射电子显微镜(TEM)、紫外-可见漫反射光谱和瞬态光电流响应谱对所合成复合光催化剂的晶体结构、微观形貌、光吸收性能和电荷分离性能进行了表征测试.XRD,SEM和TEM结果显示,结晶完好的BiOI呈小片状均匀分散在g-C_3N_4纳米薄片表面;紫外漫反射光谱表明,纳米片复合材料的吸光性能较g-C_3N_4薄片有显著提升;瞬态光电流测试证明,复合材料较单一材料有更好的电荷分离与迁移性能.在可见光催化降解RhB的测试中,BiOI/g-C_3N_4纳米片复合光催化剂显示出了优异的催化活性和稳定性,其光降解活性分别为纯BiOI和g-C_3N_4的34.89和1.72倍;自由基捕获实验发现,反应过程中的主要活性物种为超氧自由基(·O_2^-),即光生电子主导整个降解反应的发生.由此可见,强的可见光吸收能力和g-C_3N_4与BiOI界面处形成的内建电场协同促进了g-C_3N_4纳米薄片的电荷分离,进而显著提高了该复合材料的可见光催化降解活性.此外,本文初步验证了在BiOI/g-C_3N_4纳米片复合光催化体系内光生电荷是依据"双向转移"机制进行分离和迁移的,而非"Z型转移"机制.

Significantly enhanced charge transfer efficiency and surface reaction on NiP_(2)/g-C_(3)N_(4) heterojunction for photocatalytic hydrogen evolution

In this work,a novel NiP_(2)/g-C_(3)N_(4)heterojunction via homogeneous precipitation method assisted by thermal phosphorization reaction was designed and constructed,and the optimized sample showed the excellent photocatalytic H_(2)evolution activity under visible-light irradiation,which was nearly 112 times higher than that of pristine g-C_(3)N_(4)sample.Experimental characterizations and DFT calculations demonstrated that the NiP_(2)nanoparticles covered on the g-C_(3)N_(4)surface can form a built-in electric field at the interface to accelerate the transfer of photoexcited electrons from g-C_(3)N_(4)to NiP_(2),crucial for hindering the recombination of electron-hole pairs.Moreover,the energy barrier of hydrogen evolution reaction can also vastly reduce when combined NiP_(2)and g-C_(3)N_(4)to construct NiP_(2)/g-C_(3)N_(4)heterojunction.This work represents a method through combing experimental and theoretical tools to thoroughly investigate the mechanism of photocatalytic process.

FGF21 alleviates microvascular damage following limb ischemia/reperfusion injury by TFEB-mediated autophagy enhancement and anti-oxidative response

Dear Editor,Microvascular damage is a pivotal pathological factor in lower limb ischemia/reperfusion(I/R)injury.1 Excessive reactive oxygen species(ROS)formation and disrupted autophagic flux have been recognized as the critical mechanism of cellular death,2,3 especially in I/R injury.Recent investigation has displayed that fibroblast growth factor 21(FGF21)exerts a protective effect against I/R injury via transcription factor EB(TFEB)-mediated autophagy and regulation of anti-oxidative response.4 However,the promising role of FGF21 in acute lower limb I/R injury remains elusive.

Sea-urchin-like ReS_(2) nanosheets with charge edge-collection effect as a novel cocatalyst for high-efficiency photocatalytic H_(2) evolution

The recombination of charge carriers arriving from the random charge movement in semiconductor pho-tocatalysts greatly limits the practical application of solar-driven H_(2)evolution.The design of photo-catalytic systems with spatially oriented charge-transfer is a promising route to achieve high charge-separation efficiency for photocatalysts.Herein,novel sea-urchin-like Re S_(2)nanosheet/TiO_(2)nanoparticle heterojunctions(SURTHs)are constructed.The unique sea-urchin-like structure endows the ReS_(2)cocat-alyst with an unusual charge edge-collection effect,which leads to a significant acceleration of charge separation and transfer,as evidenced by the well-designed selective photodeposition of Pt quantum dots in SURTHs.The markedly improved charge transfer capacity contributes to a high photocatalytic H_(2)evo-lution rate of 3.71 mmol h^(−1)g^(−1)for SURTHs(an apparent quantum efficiency(AQE)of 16.09%),up to 231.9 times by contrast with that of P25 TiO_(2).This work would provide a new platform for designing the high-efficiency cocatalyst/photocatalyst system with excellent charge transfer capacity.

2D/2D atomic double-layer WS_(2)/Nb_(2)O_(5)shell/core nanosheets with ultrafast interfacial charge transfer for boosting photocatalytic H_(2)evolution

Low-efficiency charge transfer is a critical factor to limit the photocatalytic H_(2)evolution activity of semiconductor photocatalysts.The interface design is a promising approach to achieve high chargetransfer efficiency for photocatalysts.Herein,a new 2 D/2 D atomic double-layer WS_(2)/Nb_(2)O_(5)shell/core photocatalyst(DLWS/Nb_(2)O_(5))is designed.The atom-resolved HAADF-STEM results unravel the presence of an unusual 2 D/2 D shell/core interface in DLWS/Nb_(2)O_(5).Taking advantage of the advanced femtosecond-resolved ultrafast TAS spectra,the average lifetime of charge carriers for DLWS/Nb_(2)O_(5)(180.97 ps)is considerably shortened as compared to that of Nb_(2)O_(5)(230.50 ps),strongly indicating that the 2 D/2 D shell/core interface enables DLWS/Nb_(2)O_(5)to achieve ultrafast charge transfer from Nb_(2)O_(5)to atomic double-layer WS_(2),thus yielding a high photocatalytic H_(2)evolution rate of 237.6 mmol/h,up to10.8 times higher than that of pure Nb_(2)O_(5)nanosheet.This study will open a new window for the development of high-efficient photocatalytic systems through the interface design.

Construction of a mineralized collagen nerve conduit for peripheral nerve injury repair

A new nerve guidance conduits(NGCs)named MC@Col containing Type I collagen(Col)and mineralized collagen(MC)was developed,enhancing mechanical and degradation behavior.The physicochemical properties,the mechanical properties and in vitro degradation behavior were all evaluated.The adhesion and proliferation of Schwann cells(SCs)were observed.In the in vivo experiment,MC@Col NGC and other conduits including Col,chitosan(CST)and polycaprolactone(PCL)conduit were implanted to repair a 10-mm-long Sprague-Dawley rat’s sciatic nerve defect.Histological analyses,morphological analyses,electrophysiological analyses and further gait analyses were all evaluated after implantation in 12 weeks.The strength and degradation performance of the MC@Col NGC were improved by the addition of MC in comparison with pure Col NGC.In vitro cytocompatibility evaluation revealed that the SCs had good viability,attachment and proliferation in the MC@Col.In in vivo results,the regenerative outcomes of MC@Col NGC were close to those by an autologous nerve graft in some respects,but superior to those by Col,CST and PCL conduits.The MC@Col NGC exhibited good mechanical performance as well as biocompatibility to bridge nerve gap and guide nerve regeneration,thus showing great promising potential as a new type of conduit in clinical applications.