Microscopy Research and Technique最新文献

This study investigates the impact of environmental factors and lipid composition on the structural and morphological properties of DPPC/DOPC (1,2-Dipalmitoyl-sn-glycero-3-phosphocholine/1,2-dioleoyl-sn-glycero-3-phosphocholine) monolayers. Temperature plays a significant role in DPPC monolayer behavior; at 15°C and 20°C, DPPC exhibits liquid expanded–liquid condensed coexistence, while at 25°C, this coexistence region disappears. Divalent ions (CaCl₂) enhance more compact and uniform DPPC packing compared to monovalent ions (KCl), reducing mean area per molecule. The incorporation of DOPC into DPPC at 20°C increases the monolayer fluidity, disrupting the DPPC domain formation. For all systems, increasing surface pressure improves surface coverage and transforms micro domains into compact and continuous films at higher pressures. These findings highlight the critical roles of ionic interactions, temperature, and lipid composition in modulating lipid monolayer properties.

Green synthesis of silver nanoparticles (AgNPs) using biological sources has emerged as a sustainable and eco-friendly alternative to conventional chemical and physical methods. This review highlights recent advancements in the green synthesis of AgNPs employing plant extracts, bacteria, fungi, and algae, with particular emphasis on their antioxidant and antibacterial applications. Phytochemicals such as flavonoids, polyphenols, and terpenoids act as natural reducing and stabilizing agents, contributing to the formation of stable nanoparticles with enhanced bioactivity. The unique properties of AgNPs, including their large surface area and unique morphology, enable effective free radical scavenging and potent antibacterial activity, offering promising solutions to oxidative stress-related diseases and multidrug-resistant bacterial infections. This review critically compares green synthesis approaches with traditional methods, outlines their advantages and limitations, and explores the mechanisms underlying the antioxidant and antibacterial actions of AgNPs. The findings highlight the potential of green-synthesized AgNPs in biomedical and environmental applications.

This study examines the deposition of chromium nitride (CrN) films on 304 stainless steel (304SS) substrates using radio-frequency (RF) magnetron sputtering, with RF power varied from 20 to 160 W in an argon atmosphere. The structural, topographical, and corrosion resistance properties of the films were analyzed using X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and electrochemical polarization measurements. Employing the atomic force microscope, morphological characteristics of CrN films under constant conditions using Minkowski Functionals were analyzed. Subsequently, by examining parameters like root-mean-square roughness, skewness, and kurtosis, the study revealed the variations in the particle distribution and their probability density as a function of deposition power alterations. Results indicate that increasing RF power enhances film crystallinity, as evidenced by intensified XRD peaks. With an increase in RF power reaching up to 80 W, there is a significant enhancement in the uniformity of the surface, resulting in an evenly spread grain pattern. Corrosion tests in 0.5 M sulfuric acid, assessed via potentiodynamic polarization, identify 80 W as the optimal RF power for maximizing corrosion resistance. This study provides insights into the relationship between film structure, surface characteristics, and corrosion behavior, highlighting key factors influencing protective performance.

This study aims to evaluate the efficacy of calcium hypochlorite in smear layer removal during root canal treatment and examine the impact of heat and agitation techniques on its performance. In this study, 160 single-rooted, straight mandibular premolars were prepared using ProTaper Next rotary files up to X4. Following preparation, samples were randomly branched into 10 groups of 16 teeth each. 5.25% calcium hypochlorite was used at 3 different temperatures: non-heated, preheated, and intracanal heated. As agitation techniques, XP-Endo Finisher, EDDY, and Passive Ultrasonic Irrigation (PUI) were used. The teeth were divided into two longitudinal sections and examined under a scanning electron microscope at ×1000 magnification. The control group exhibited the highest smear layer retention in all regions, while the intracanal heated PUI group provided the most effective cleaning in all areas. The results showed that heating calcium hypochlorite and using agitation techniques are more effective for smear layer removal.

This study aimed to compare the design characteristics, cyclic fatigue resistance, and metallurgical properties of original, replica-like, and counterfeit nickel-titanium systems. One hundred Ni-Ti files were evaluated and categorized into four groups: the original (Of-Reciproc Blue R25) system, a replica-like (Rf-Recip-One Files Blue R25) system, and two counterfeit (Cf1, Cf2) systems. The design characteristics were assessed based on packaging features, manufacturing defects observed using a stereomicroscope, tip design analyzed via scanning electron microscopy (SEM), and taper and tip diameter measurements conducted with Image J software (National Institutes of Health, Bethesda, MD, USA). Cyclic fatigue testing was performed at body temperature in an artificial canal with a 60° angle of curvature and a 5 mm radius of curvature. Metallurgical properties were examined using differential scanning calorimetry (DSC) and energy-dispersive spectroscopy (SEM-EDS). Statistical analysis was conducted using the Kruskal–Wallis test with post hoc Dunn-Bonferroni tests, with the significance level set at 5%. The Cf systems were distinguished from the Of system by the observation of manufacturing defects under a stereomicroscope. While the Of and Rf systems exhibited passive tip designs, the Cf systems displayed active tip designs. The Rf system showed tip diameter and taper values similar to those of the Of system, whereas the Cf1 system demonstrated lower tip diameter and taper values compared to the Of system. Cyclic fatigue test results revealed no statistically significant difference in fracture times between the systems. DSC analysis indicated that the Of system was in the austenite phase at body temperature, while the other systems were in the martensite phase. SEM-EDS analysis revealed similar nickel-titanium compositions across all systems. The Rf system showed similar design, mechanical, and metallurgical properties to the Of system, while Cf systems lacked consistency in standardization and design. The presence of manufacturing defects, along with discrepancies in claimed design specifications such as tip diameter and taper, and the fact that counterfeit systems exist in a different metallurgical phase compared to the original system, may predispose clinicians to potential complications during clinical use.