Chitosan/Sodium Alginate Multilayer pH-Sensitive Films Based on Layer-by-Layer Self-Assembly for Intelligent Packaging

The abuse of plastic food packaging has brought about severe white pollution issues around the world.Developing green and sustainable biomass packaging is an effective way to solve this problem.Hence,a chitosan/sodium alginate-based multilayer film is fabricated via a layer-by-layer(LBL)self-assembly method.With the help of superior interaction between the layers,the multilayer film possesses excellent mechanical properties(with a tensile strength of 50 MPa).Besides,the film displays outstanding water retention property(blocking moisture of 97.56%)and ultraviolet blocking property.Anthocyanin is introduced into the film to detect the food quality since it is one natural plant polyphenol that is sensitive to the pH changes ranging from 1 to 13 in food when spoilage occurs.It is noted that the film is also bacteriostatic which is desired for food packaging.This study describes a simple technique for the development of advanced multifunctional and fully biodegradable food packaging film and it is a sustainable alternative to plastic packaging.

In vitro corrosion and antibacterial properties of layer-by-layer assembled GS/PSS coating on AZ31 magnesium alloys

To enhance the corrosion resistance of magnesium（Mg） alloy and to impart its surface with antibacterial functionality for inhibiting biofilm formation and biocorrosion, Mg（OH）2 films were fabricated on AZ31 magnesium alloy substrates by an in-situ hydrothermal method and well-defined multilayer coatings, consisting of gentamicin sulfate（GS） and poly（sodium 4-styrene sulfonate）（PSS）, were prepared via layer-by-layer（Lb L） assembly. The morphologies, chemical compositions and corrosion resistance of the obtained（PSS/GS）n/Mg sample were investigated using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, electrochemical methods and immersion tests. Finally, the bactericidal activity of（PSS/GS）n/Mg samples against Staphylococcus aureus was assessed by the zone of inhibition methods and plate-counting method. The so-synthesized composite coating on the Mg alloy substrates exhibits good corrosion resistance and antibacterial performance, which make them attractive as coatings for medical implanted devices.

改良LBL-PBL-LBL教学法在骨科见习学生教学中的应用

目的探究改良传统授课模式-基于问题的学习-传统授课模式(lecture-based learning,problem-based learning,lecture-based learning,LBL-PBL-LBL)教学法在骨科见习学生教学中的应用效果。方法选取2023年3-11月河北大学附属医院骨科接收的120名见习学生,采取计算机等量随机方式进行分组,对照组(n=60)学生见习教学应用LBL教学法,观察组(n=60)给予改良LBL-PBL-LBL教学法,见习结束后,通过对2组学生发放调查问卷和进行理论和实践考核,收集对比2组见习学生评教情况、考试成绩及教学满意度。结果对比2组学生教学后数据,其中观察组见习学生评分[自主学习能力:(3.14±0.35)分、小组协作能力:(3.07±0.32)分、学习兴趣:(2.93±0.42)分、知识点掌握:(3.29±0.62)分、实践技能:(3.28±0.63)分]高于对照组[自主学习能力:(2.29±0.18)分、小组协作能力:(1.65±0.24)分、学习兴趣:(2.17±0.38)分、知识点掌握:(2.16±0.34)分、实践技能:(2.56±0.48)分],差异有统计学意义(P<0.001);观察组的考试成绩[理论考核:(84.12±0.81)分、实践考核:(88.59±0.68)分]优于对照组[理论考核:(72.32±0.87)分、实践考核:(71.16±0.32)分],差异有统计学意义(P<0.001);观察组学生对改良LBL-PBL-LBL教学法的教学满意度[教学组织管理:(3.22±0.32)分、教师带教能力:(3.69±0.24)分、教学效果满意度:(3.39±0.55)分、教学模式认可度:(3.24±0.36)分]优于对照组[教学组织管理:(2.12±0.27)分、教师带教能力:(2.56±0.22)分、教学效果满意度:(2.45±0.38)分、教学模式认可度:(1.96±0.21)分],差异有统计学意义(P<0.001)。结论对骨科见习学生应用改良LBL-PBL-LBL教学法进行教学,教学效果有显著的改善,不仅能够有效增加见习学生的理论知识储备,提高对骨科临床实践的认识,还能提高医院的教学满意度。

消化内镜教学中PBL与LBL教学效果的Meta分析

目的 对以问题为基础的教学法(problem-based learning,PBL)与传统的以授课为基础的教学法(lecturebased learning,LBL)对消化内镜教学效果的影响进行Meta分析。方法 以“消化内镜”和“PBL”为主要关键词,全面检索中国知网、万方医药期刊和维普中文期刊数据库,收集PBL教学法对消化内镜教学影响的随机对照试验,检索时限为2000年1月至2023年6月。对纳入的文献进行发表偏倚风险检验和质量评估,采用Revman Manager 5.2统计学软件进行Meta分析。结果 经筛选共纳入10篇随机对照试验。Meta分析结果显示,PBL教学法与LBL教学法相比,对学生消化内镜学习效果有明显的提升,差异有统计学意义(P <0.05)。其中理论成绩MD=7.52,95%CI为4.88~10.15,Z=5.59,P <0.001;胃镜操作次数MD=3.61,95%CI为1.87~5.35,Z=4.07,P <0.001;胃镜操作时间MD=-2.72,95%CI为-3.28~-2.15,Z=9.48,P <0.05;结肠镜操作例数MD=3.93,95%CI为3.59~4.27,Z=22.76,P <0.001;结肠镜操作时间MD=-8.40,95%CI为-11.32~-5.48,Z=5.64,P <0.001。结论 在消化内镜的教学中,学生应用PBL教学法的理论成绩、操作成绩均优于传统LBL教学法。

LBL联合PBL教学法在儿科呼吸系统疾病教学中的应用

呼吸系统疾病是儿童时期常见病、多发病,传统讲授式(lecture-based learning,LBL)教学法联合问题导向性学习(problem-based learning,PBL)教学法已成为新的教学趋势。为提高儿科学呼吸系统疾病的教学质量,通过分析LBL教学法和PBL教学法的优点、缺点,并根据“儿科学”课程特点,提出在课程的《支气管哮喘》章节开展LBL联合PBL教学的具体方法和步骤。教学效果表明,在儿科呼吸系统疾病教学中,采用LBL联合PBL教学法不仅能使学生全面、系统地掌握课程内容,还能提高学生分析问题、解决问题和团队协作能力。

PBL联合LBL教学模式在针灸教学中的应用研究

本研究旨在探讨 PBL(Problem-Based Learning,以问题为基础的学习)联合 LBL(Lecture-Based Learning,以授课为基础的学习)教学模式在针灸教学中的应用效果。通过对比传统教学模式,分析 PBL 联合 LBL 教学模式对学生学习兴趣、理论知识掌握、实践技能水平以及综合能力提升等方面的影响。研究结果表明,该联合教学模式在提高学生的学习积极性、增强临床实践能力和培养创新思维等方面具有显著优势,为针灸教学改革提供了有益的参考和借鉴。

PBL教学模式与LBL教学模式在心血管内科见习教学中的应用分析

对心血管内科见习教学中,实施PBL教学模式(以问题为导向的教学方法)与LBL教学模式(以授课为基础的教学方法)的教学效果进行评估,分析各指标状况。方法 在2017级临床医学专业在本院见习班120位同学中,选出60名成绩良好及以上的学生,通过随机分组,分为研究、对照两组,每组30名,上述组别分别给予PBL教学模式、LBL教学模式。分析上述教学措施实施后学生学习情况,对比学习成绩、教学满意度等指标状况。结果 理论及实践能力评估结果显示,研究组评分更高(P<0.05);与对照组相比,研究组对教学方案的满意度更高,组间数据对比有意义(P<0.05)。结论 PBL教学模式的实施可以帮助学生更好的提升学习成绩,且与LBL教学模式相比,学生的满意度较高,各院可加以推广,实现最佳教学效果。

PBL和LBL结合实际病例教学方法对临床麻醉教学效果影响评价

探讨结合PBL模式、LBL模式进行临床麻醉的实际病例教学的效果。方法 由麻醉科择取50名实习学生进行分组,采取PBL模式、LBL模式进行临床麻醉的实际病例教学(研究组)、常规教学模式(对照组)。结果 教学效果指标以及教学后自主学习能力分值的对比上,研究组更高,P<0.05;而教学前自主学习能力分值的两组数据对比结果是P>0.05。结论 结合PBL模式、LBL模式进行临床麻醉的实际病例教学,有助于实习学生教学效果获得大幅度增加。

In vitro corrosion resistance and antibacterial properties of layer-by-layer assembled chitosan/poly-L-glutamic acid coating on AZ31 magnesium alloys

Surface functionalization of magnesium(Mg)alloys is desired to obtain the surfaces with both improved corrosion resistance and antibacterial property.A corrosion-resistant and antimicrobial coating was prepared on Mg alloy surface by layer-by-layer(LbL)assembly of chitosan(CHI)and poly-L-glutamic acid(PGA)by electrostatic attraction.The functionalized surfaces of the Mg alloys were characterized by field-emission scanning electron microscopy(FE-SEM),Fourier transform infrared(FT-IR)spectroscopy and electrochemical tests.The bactericidal activity of the samples against Staphylococcus aureus was assessed by the zone of plate-counting method.The obtained coating on the Mg alloy substrates exhibits good corrosion resistance and antibacterial performance.

In vitro corrosion resistance,antibacterial activity and cytocompatibility of a layer-by-layer assembled DNA coating on magnesium alloy

A chitosan/deoxyribonucleic acid(CHI/DNA)_(5)coating was constructed by layer-by-layer(LbL)assembly dip coating method with Mg(OH)_(2)coating as an inner protective layer on AZ31 alloy.X-ray diffractometry,X-ray photoelectron spectrometry,Fourier transform infrared spectroscopy and field-emission scanning electron microscopy were utilized to represent the chemical compositions and surface morphologies of the coatings.Electrochemical tests and hydrogen evolution measurements were implemented to confirm the good corrosion resistance of the composite coating in artificial body fluid.Antimicrobial activity of the composite coatings was tested via the plate-counting method,and the cytotoxicity of the samples was appraised by MTT assay and Live/dead staining.A double action was put into effect for the composite coating,which the inner Mg(OH)2 coating plays the part of physical barrier,and the outer(CHI/DNA)5 coating is employed as an inducer to fabricate a biocompatible Ca-P corrosion product coating during immersion,making up for its thin thickness.Otherwise,the composite coating is also beneficial for the growth of bone,resulting from the biomineralization effect of the outer polyelectrolyte multilayer.The good antibacterial property of the(CHI/DNA)5/Mg(OH)2 coating is ascribed to the contact-killing strength of CHI.Thus,the obtained(CHI/DNA)5/Mg(OH)2 coating has a wide application prospect in the field of Mg-based bone implantation.

Gradient nanoporous phenolics as substrates for high-flux nanofiltration membranes by layer-by-layer assembly of polyelectrolytes

Thin film composite(TFC) membranes represent a highly promising platform for efficient nanofiltration(NF)processes. However, the improvement in permeance is impeded by the substrates with low permeances. Herein,highly permeable gradient phenolic membranes with tight selectivity are used as substrates to prepare TFC membranes with high permeances by the layer-by-layer assembly method. The negatively charged phenolic substrates are alternately assembled with polycation polyethylenimine(PEI) and polyanion poly(acrylic acid)(PAA)as a result of electrostatic interactions, forming thin and compact PEI/PAA layers tightly attached to the substrate surface. Benefiting from the high permeances and tight surface pores of the gradient nanoporous structures of the substrates, the produced PEI/PAA membranes exhibit a permeance up to 506 L? m-2?h-1?MPa-1, which is ~2–10 times higher than that of other membranes with similar rejections. The PEI/PAA membranes are capable of retaining N 96.1% of negatively charged dyes following the mechanism of electrostatic repulsion. We demonstrate that the membranes can also separate positively and neutrally charged dyes from water via other mechanisms.This work opens a new avenue for the design and preparation of high-flux NF membranes, which is also applicable to enhance the permeance of other TFC membranes.

PBL、LBL两种教学方法在中西医结合心血管内科临床教学的应用及对其操作能力的影响

探究以问题为导向的教学法(Problem-Based Learning,PBL)、以讲授式教学法(Lecture-Based Learning,LBL)两种教学方法在中西医结合心血管内科临床教学的应用及对其操作能力的影响。方法 以医院中西医结合心血管内科为试点,近三年共计接收实习生70名,根据实习生入科时间分组,2021年9月3日至2023年2月1日接收实习生35名开展LBL教学法,2023年3月1日至2024年6月30日接收实习生35名开展PBL教学法,比对教学应用效果。结果 PBL组实习生中医查体技能、药械操作技能、应急解决能力等操作能力考核成绩均高于LBL组(P<0.05);带教前实习生自我评价显示知识学习兴趣、自主学习积极性、寻求真相能力、同伴交流及师生沟通水平、批判性思维评分相一致,带教后自我评价提升,PBL组实习生自评知识学习兴趣、自主学习积极性、寻求真相能力、同伴交流及师生沟通水平、批判性思维分数均高于LBL组(P<0.01);PBL组实习生认为PBL教学氛围、教学内容生动性、师生关系及沟通能力培养满意度高于LBL组(P<0.05)。结论 PBL教学方法在中西医结合心血管内科教学中对提高实习生操作能力显著优于LBL,激发实习生自主学习能力,受到实习生一致认可,教学方案可推广。

PBL联合LBL在血管外科临床见习教学中的应用分析

分析PBL和LBL教学模式相结合,在血管外科临床见习教学的实际价值。方法 选取2021年1月至2023年1月在我院血管外科见习的学生,随机分观察组和对照组,观察组学生采取PBL和LBL两种教学模式相结合,对照组学生采取LBL教学模式。对比学生的考试成绩。结果 观察组学生的考试成绩均高于对照组,P<0.05。结论 在血管外科临床见习中,采用PBL和LBL两种教学模式相结合的方式,能提高学生的考试成绩,丰富理论知识和实践经验,提升教学水平,值得推广。

Enhanced performance of a solar cell based on a layer-by-layer self-assembled luminescence down-shifting layer of core–shell quantum dots

In this paper, core–shell quantum dots(QDs) with two polar surface functional groups(ZnSe/ZnS–COOH QDs and ZnSe/ZnS–NH_2 QDs) are synthesized in an aqueous phase. Photoluminescence(PL) and absorption spectra clearly indicate luminescence down-shifting(LDS) properties. On the basis of QDs, surface functional group multilayer LDS films(MLDSs) are fabricated through an electrostatic layer-by-layer(LBL) self-assembly method. The PL intensity increases linearly with the number of bilayers, showing a regular and uniform film growth. When the M-LDS is placed on the surface of a Si-based solar cell as an optical conversion layer for the first time, the external quantum efficiency(EQE) and shortcircuit current density(Jsc) notably increases for the LDS process. The EQE response improves in a wavelength region extending from the UV region to the blue region, and its maximum increase reaches more than 15% between 350 nm and 460 nm.

Layer-by-layer electrostatic selfassembly of anionic and cationic carbon nanotubes

The layer-by-layer(LBL) self assembly of anionic and cationic multi-walled carbon nanotubes(MWNTs) through electrostatic interaction has been carried out to fabricate all-MWNT multilayer films.The alternate uniform assembly of anionic and cationic MWNTs was investigated by UV-vis spectroscopy.Scanning electron microscopy(SEM) images displayed the growth of the MWNT films.

Solid Additive-Assisted Layer-by-Layer Processing for 19%Efficiency Binary Organic Solar Cells

Morphology is of great significance to the performance of organic solar cells(OSCs),since appropriate morphology could not only promote the exciton dissociation,but also reduce the charge recombination.In this work,we have developed a solid additive-assisted layer-by-layer(SAA-LBL)processing to fabricate high-efficiency OSCs.By adding the solid additive of fatty acid(FA)into polymer donor PM6 solution,controllable pre-phase separation forms between PM6 and FA.This intermixed morphology facilitates the diffusion of acceptor Y6 into the donor PM6 during the LBL processing,due to the good miscibility and fast-solvation of the FA with chloroform solution dripping.Interestingly,this results in the desired morphology with refined phase-separated domain and vertical phase-separation structure to better balance the charge transport/collection and exciton dissociation.Consequently,the binary single junction OSCs based on PM6:Y6 blend reach champion power conversion efficiency(PCE)of 18.16%with SAA-LBL processing,which can be generally applicable to diverse systems,e.g.,the PM6:L8-BO-based devices and thick-film devices.The efficacy of SAA-LBL is confirmed in binary OSCs based on PM6:L8-BO,where record PCEs of 19.02%and 16.44%are realized for devices with 100 and 250 nm active layers,respectively.The work provides a simple but effective way to control the morphology for high-efficiency OSCs and demonstrates the SAA-LBL processing a promising methodology for boosting the industrial manufacturing of OSCs.

在临床输血实习带教中应用PBL、LBL教学模式的效果分析

探究临床输血实习带教期间运用PBL、LBL教学模式的效果。方法 于2021年1月-2022年1月抽取200名临床输血实习生按照随机数字表法分为参考组及实验组,每组100名,其中前者行LBL,后者行PBL。对两组教学效果进行评价。结果 实验组理论、操作考试成绩显高于参考组(P<0.05)。实验组实践反馈情况显优于参考组(P<0.05)。实验组教学满意度显高于参考组(P<0.05)。结论 将PBL教学法应用在临床输血实习中能够较好地提高实习生理论和操作考试的成绩,增强实习的实际操作能力,从而使实习生对教学工作的满意程度得到提高。

LBL+Seminar+CBL三联教学法在口腔正畸住院医师规范化培训中的应用

口腔正畸学为二级学科,其理论知识复杂、学习难度大、治疗周期长,在本科生学习阶段接触甚少,缺乏应有临床教育。口腔正畸学教育大部分来自毕业后再教育,如上级医院进修、住院医师规范化培训等;但带教老师需要在短时间内提升口腔正畸学规范化培训效果,提升口腔正畸学专业水准,缓解口腔正畸医师紧缺的现况。LBL教学法(Lecture-Based Learning)以讲授课程为基础,是最传统的讲课方法;Seminar教学法是指住培指导老师提出主题,一般为本专业重点或难点,内容与LBL互补或加强;学生成为该主题的主讲报告人,与教师及各专业轮转住培医师共同讨论分析、开展学术交流;CBL以病例为基础(case-based learning,CBL)的教学模式是一种通过分析病历重现真实临床场景,增强学生临床实践能力、分析和解决问题能力的互动式教学方式。本文在讲述口腔正畸学住院医师规范化培训现状的基础上,对LBL+Seminar+CBL相结合的教育形式应用于口腔正畸学住培进行探讨,为满足社会对口腔正畸治疗不断扩增的需求而培养高质量高水平的口腔正畸学医师。

Layer-by-layer growth of ZIF-8 on electrospun carbon nanofiber membranes for high-performance supercapacistor electrode

In the past few decades, supercapacitor(SC) has attracted great attention due to its significant advantages over traditional rechargeable battery systems, such as high power density, fast charge-discharge rate, long cycle life and environmental friendliness [1]. Up to now, supercapacitors have been widely used in backup power, electric vehicles, mobile power and so on [2,3].

Application of Layer-by-Layer Solidification Principle to Optimization of Large Chain Wheel Foundry Technology

In order to get a sound casting of the alloy with a solidification range, the principle of directional solidification (DS) and the layer-by-layer solidification(LBLS) should be followed, especially in designing foundry process of steel casting. Using the principles, the reasons for the forming of the defects on the surface of the chain wheels teeth and groove and the forming of MT (magnetic particle testing) thin lines were analyzed. The results of the metallographic observation and the numerical simulation show that the low temperature gradient results in a wider mushy zone at the S/L interface that causes the defects and MT thin lines on the surface of the chain wheel casting. Based on the analysis, a new casting technology of the chain wheel was designed and used in the casting production successfully.