Hasil untuk "Microscopy"

J. Dowling, B. Boycott

F. Lafay

W. Franke, E. Schmid, Mary OSBORNt et al.

P. Bastiaens, A. Squire

B. Hecht, Beate Sick, U. Wild et al.

N. Dudovich, D. Oron, Y. Silberberg

E. Kirkland

Manosi Roy, Jose F. Castaneda, Sharonda J. LeBlanc et al.

Resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) is a versatile technique for depositing hybrid organic–inorganic perovskites (HOIPs) and has previously been used to deposit two-dimensional (2D) and three-dimensional HOIPs. This study investigates the growth mechanisms of 2D phenethylammonium lead iodide [(PEA)2PbI4] thin films deposited by RIR-MAPLE, focusing on their early nucleation and film formation processes. By varying deposition times and substrate surface properties, the evolution of the crystal structure, surface morphology, and optical properties of (PEA)2PbI4 films was characterized. Standard characterization techniques provided critical insights but lacked sensitivity to capture early stage nucleation and excited-state dynamics. Fluorescence lifetime imaging microscopy addressed this gap, revealing three distinct excited-state processes and their spatial distribution during film growth. These findings connect how the underlying surface properties and the RIR-MAPLE deposition method affect the resulting pure 2D (PEA)2PbI4 film morphology and spatially resolved excited-state relaxation dynamics.

Wonhee Ko, Seoung‐Hun Kang, Qiangsheng Lu et al.

Abstract Quantum materials with novel spin textures from strong spin‐orbit coupling (SOC) are essential components for a wide array of proposed spintronic devices. Topological insulators have a necessary strong SOC that imposes a unique spin texture on topological states and Rashba states that arise on the boundary, but there is no established methodology to control the spin texture reversibly. Here, it is demonstrated that functionalizing Bi2Se3 films by altering the step‐edge termination directly changes the strength of SOC and thereby modifies the Rashba strength of 1D edge states. Scanning tunneling microscopy/spectroscopy shows that these Rashba edge states arise and subsequently vanish through the Se functionalization and reduction process of the step edges. The observations are corroborated by density functional theory calculations, which show that a subtle chemical change of edge termination fundamentally alters the underlying electronic structure. Importantly, fully reversible and repeatable switching of Rashba edge states across multiple cycles at room temperature is experimentally demonstrated. The results imply Se functionalization as a practical method to control SOC and spin texture of quantum states in topological insulators.

S. Amemiya, A. Bard, F. Fan et al.

Z. Perlman, M. Slack, Yan Feng et al.

Afia Yasmin, Bristy Biswas, Md. Lutfor Rahman et al.

CoFe2O4 was synthesized at 150 °C, 180 °C, and 210 °C temperatures using hydrothermal method to find the effect on its structural, magnetic, electric, and optical properties. The saturation magnetization, coercivity and magnetic anisotropy was found using Vibrating Sample Magnetometer (VSM), ranging from 50.36 to 53.66 emu/g. XRD (X-ray Diffraction Analysis) and SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared Spectroscopy) was used for structural analysis verifying the spinel ferrite structure with a single phase. The crystalline size and lattice strain was found using Size-Strain Plot (SSP) and Debye-Scherrer (D-S) method which proved that as the synthesis temperature increased, the crystallite size also increased. The crystalline size ranges from 39.40 to 82.24 nm as observed by XRD. SEM analysis found the crystal size range to be from 9 to 12 nm. It was found that the optimum temperature to synthesize cobalt ferrite nanoparticles are at 180 °C for sample H2 with a crystal size of 82.24 nm and band gap energy of 2.60 eV. The Ms value was determined to be 50.36 emu/g for H2 sample with Rs value of 0.31.

Jutarat Phuensuriya, Panida Thanyasrisung, Chutima Trairatvorakul et al.

Abstract Objective Silver diamine fluoride (SDF) is widely used for caries arrest due to its ease of application, minimal caries removal, low patient discomfort, and cost-effectiveness. However, the recommended 60-second (sec) application time may be impractical in patients with limited compliance. This study evaluated the effects of 10-sec versus 60-sec SDF application, with and without light curing, on arresting artificial dentinal caries by analyzing three parameters—percentage change in mean lesion depth (%∆LD), percentage change in mean mineral density (%∆MD), and penetration depth (PD)— assessing surface morphology and elemental composition of the lesions. Materials and methods Artificial dentin lesions were prepared on 40 slices from 10 permanent molars and randomly assigned to four groups (n = 10): (1) SDF60 (60 s application), (2) SDF10 (10 s application), (3) SDF60LC (60 s application + 20 s light curing), and (4) SDF10LC (10 s application + 20 s light curing). The caries activity was generated by a 7-day bacterial pH-cycling model. Micro-computed tomography (Micro-CT) was used to analyze %∆LD, %∆MD, and PD. Surface morphology and elemental composition were examined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Results SDF60LC produced the greatest reduction in lesion depth (%∆LD), the largest increase in mineral density (%∆MD), and the highest penetration depth (PD). SDF10 showed significantly less %∆LD and %∆MD compared with both SDF60 and SDF60LC. %∆LD and %∆MD of SDF10LC were not significantly different from either SDF60 or SDF10. However, SDF10LC achieved significantly greater PD than SDF10. Conclusions A 60-sec SDF application with light curing appeared to produce the most favorable outcomes in terms of lesion depth reduction, mineral density gain, and penetration depth. A 10-sec SDF application with light curing produced results comparable to a 60-sec SDF application. Clinical relevance Although a 60-sec SDF application with light curing seems the most effective under laboratory conditions, a shortened 10-sec SDF application with light curing may offer a practical alternative in low-compliance patients. Clinical studies are required to confirm these findings.

Kaustav Das, Ishita Ghosh, Soumalya Chakraborty et al.

Abstract Altering surface chemistry of functional materials is an attractive route to enable large property enhancements without sacrificing overall structural-order, appealing to diverse fields of application sciences; however, the same remains unexplored for organic crystalline materials. Herein, piezoelectricity in pharmaceutical crystals is reported to show colossal surface charges driven by mechanical fracture — where a collection of dipoles arranged in polar head-to-tail fashion generates opposite surface charges on freshly fractured faces — causing them to actuate large distances over 75 µm in milliseconds. Kelvin probe force microscopy is leveraged to show many-fold surface potential enhancement in fractured surfaces relative to the pristine crystals. Further, complementarity of the surface potentials in a pair of fractured crystal shards and asymptotic decay behaviour with time are observed. Newly formed surfaces of the pharmaceutical crystals show long-lasting charges despite their relatively lower piezo-response confirmed by bulk piezometry. To establish the generality of surface phenomena, statistical analyses (≈50 samples) of post-fracture-attraction behaviour of crystals are performed. Finally, the application of fracture-driven surface charges in industrial processes is achieved by investigating flow-property and tablet-strength of bulk pharmaceutical materials. This multiscale approach unveils the symmetry-dependency of surface charges in fractured materials, and probes the same for utilisation in bulk-property engineering.

Zhuo-ma Dawa, Zhuo-ma Dawa, Ting Zhai et al.

IntroductionAlveolar echinococcosis (AE) is a chronic zoonotic disease caused by the larvae of the Echinococcus multilocularis (E. multilocularis). The current chemotherapy for AE relies on albendazole and mebendazole, which exhibit only parasitostatic rather than parasiticidal effects. Therefore, there is a need to find new anti-Echinococcosis drugs. Pseudolaric acid B (PAB) has been described to have strong antiparasitic effects. However, the in-depth mechanism by which PAB acts against E. multilocularis remains unclear.MethodsTo evaluate the effect of a PAB intervention on protoscoleces, metacestode vesicles and germinal cells in E. multilocularis in vitro. In addition, the effects of PAB on T lymphocyte and collagen synthesis were evaluated after PAB administration in a mouse model.ResultsMetacestode vesicles and germinal cells were successfully cultured, and specific genes were amplified via RT-PCR to identify the protoscoleces, vesicles, and germinal cells as the sources of E. multilocularis. In vitro studies have demonstrated that PAB exhibits dose- and concentration-dependent cytotoxicity against E. multilocularis protoscoleces. Scanning electron microscopy revealed that the microvilli structure of the protoscolex was destroyed and the rostellar hooks had fallen off. PAB induced. The release of PGI from the metacestode vesicles, leading to the structural destruction of the inner surfaces. PAB suppressed the proliferation of germinal cells. After PAB treatment, the serum and the host tissue surrounding the metacestodes IFN-γ levels were upregulated and the IL-4 and IL-10 levels was downregulated. After PAB treatment, the levels of CD4+ T lymphocytes increased and the levels of CD8+ T lymphocytes decreased in the host tissue surrounding the metacestodes and the spleen. The proportions of the Th1 and Th17 cell subpopulations were increased and the proportion of Th2 cell and Treg cell subpopulations was decreased in the host tissue surrounding the metacestodes. Additionally, collagen deposition was increased after PAB treatment. PAB suppressed the expression of matrix metalloproteinases (MMPs 1, 2, 3, 9, 13) and the activation of the PI3K/AKT signaling pathway in the host tissue surrounding the metacestodes.ConclusionPAB has a significant killing effect on E. multilocularis, suggesting that it is a potential candidate for the treatment of AE.

R. Jain, L. Munn, D. Fukumura

Cornelia-Ioana Ilie, Angela Spoiala, Cristina Chircov et al.

The gut microbiota dysbiosis that often occurs in cancer therapy requires more efficient treatment options to be developed. In this concern, the present research approach is to develop drug delivery systems based on magnetite nanoparticles (MNPs) as nanocarriers for bioactive compounds. First, MNPs were synthesized through the spraying-assisted coprecipitation method, followed by loading bee pollen or bee bread extracts and an antitumoral drug (5-fluorouracil/5-FU). The loaded-MNPs were morphologically and structurally characterized through transmission electron microscopy (TEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Dynamic Light Scattering (DLS), and thermogravimetric analysis. UV-Vis spectroscopy was applied to establish the release profiles and antioxidant activity. Furthermore, the antibacterial and antitumoral activity of loaded-MNPs was assessed. The results demonstrate that MNPs with antioxidant, antibacterial, antiproliferative, and prebiotic properties are obtained. Moreover, the data highlight the improvement of 5-FU antibacterial activity by loading on the MNPs’ surface and the synergistic effects between the anticancer drug and phenolic compounds (PCs). In addition, the prolonged release behavior of PCs for many hours (70–75 h) after the release of 5-FU from the developed nanocarriers is an advantage, at least from the point of view of the antioxidant activity of PCs. Considering the enhancement of <i>L. rhamnosus</i> MF9 growth and antitumoral activity, this study developed promising drug delivery alternatives for colorectal cancer therapy.

Nidia Leticia Ruiz-Zambrano, Viridiana Tejada-Ortigoza, Sergio O. Serna-Saldívar et al.

Powder beverage bases were developed using extruded and hydrolyzed chickpea supernatant through freeze-drying. This study evaluated the effects of spray-drying and adjuvant incorporation for producing powders and supernatant fermentation with LAB strains prior freeze-drying on the carbohydrate composition, structural integrity, and physical properties of chickpea beverage base powders. All powders had low insoluble (<0.2 %) and soluble (<3 %) dietary fiber contents due to processing. Starch content decreased below 9.49 % when using adjuvants and 10.61 % during fermentation. Both treatments also reduce raffinose oligosaccharide content below 6.1 mM/100 g. Spray-drying and adjuvant addition promoted a more amorphous starch structure, enhancing solubility, while fermentation induced more crystallinity, according to FTIR data. Microscopy showed small particle clusters and lack of birefringence. SEM images revealed starch granule damage from both fermentation and spray-drying, with more uniform particles in spray-dried powders. Spray-drying resulted in the smallest particle sizes (455-457 nm) and higher absolute zeta potential (8.12-9.51), indicating greater stability. Fermentation had the opposite effect, negatively impacting the colloidal system stability. Samples had a pH close to 6, except fermented powders with a pH of 3.6, affecting colloidal stability. Fermentation significantly reduced solubility but without practical implications, as all samples had solubility values over 93 %, which is desirable for beverage-based powders. Spray-drying and fermentation altered the carbohydrate profile and structure of the powders. Fermentation prior producing powders may provide benefits, but it slightly decreases the system stability. Spray-drying can be used instead of freeze-drying to produce stable chickpea base powders that are highly soluble.

T. Taubner, D. Korobkin, Y. Urzhumov et al.

R. Ober, R. Ober, S. Ram et al.