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Corrosion Inhibition of Aluminium Alloy AA6063-T5 by Vanadates: Local Surface Chemical Events Elucidated by Confocal Raman Micro-Spectroscopy
摘要： Chemical interactions between aqueous vanadium species and aluminium alloy AA6063-T5 were investigated in vanadate-containing NaCl solutions. Confocal Raman and X-ray photoelectron spectroscopy experiments were utilised to gain insight into the mechanism of corrosion inhibition by vanadates. A greenish-grey coloured surface layer, consisting of V+4 and V+5 polymerized species, was seen to form on the alloy surface, especially on top of cathodic micrometre-sized IMPs, whereby suppressing oxygen reduction kinetics. The results suggest a two-step mechanism of corrosion inhibition in which V+5 species are first reduced to V+4 or V+3 species above cathodic IMPs, and then oxidized to mixed-valence V+5/V+4 polymerized compounds.
关键词： B. XPS,B. Raman Spectroscopy,C. Vanadate Inhibitor,A. Aluminium,B. SEM,A. Alloy
更新于2025-09-04 15:30:14
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Label-free characterization of exosome via surface enhanced Raman spectroscopy for the early detection of pancreatic Cancer
摘要： Pancreatic cancer is a highly lethal malignancy. Lack of early diagnostic markers makes timely detection of pancreatic cancer a highly challenging endeavor. Exosomes have emerged as information-rich cancer specific biomarkers. However, characterization of tumor-specific exosomes has been challenging. This study investigated the proof-of principal that exosomes could be used for the detection of pancreatic cancer. Label-free analysis of exosomes purified from normal and pancreatic cancer cell lines was performed using surface enhanced Raman Spectroscopy (SERS) and principal component differential function analysis (PC-DFA), to identify tumor-specific spectral signatures. This method differentiated exosomes originating from pancreatic cancer or normal pancreatic epithelial cell lines with 90% accuracy. The cell line trained PC-DFA algorithm was next applied to SERS spectra of serum-purified exosomes. This method exhibited up to 87% and 90% predictive accuracy for HC and EPC individual samples, respectively. Overall, our study identify utility of SERS spectral signature for deciphering exosomal surface signature.
关键词： surface enhanced Raman spectroscopy,liquid biopsy,Pancreatic cancer,exosome,label-free
更新于2025-09-04 15:30:14
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A Simple Synthetic Approach To Prepare Silver Elongated Nanostructures: From Nanorods to Nanowires
摘要： A procedure for one-pot preparation and characterization of silver 1D nanostructures is described. The main advantages of this synthetic approach are the simplicity and reproducibility, where the size of the final product can be controlled just by changing the reaction time. This experiment is designed as a laboratory introduction to colloidal chemistry for undergraduate and graduate students; they can appreciate the role of the different reagents in a relatively complex reaction and understand the relation between the morphology of a metal at the nanoscale and some macroscopic properties, such as its visible absorption spectrum (i.e., color).
关键词： Nanotechnology,Synthesis,Second-Year Undergraduate,UV?Vis Spectroscopy,Physical Chemistry,Laboratory Instruction,Hands-On Learning/Manipulatives,First-Year Undergraduate/General,Metals,Colloids
更新于2025-09-04 15:30:14
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ATR FTIR Spectroscopic Study on Insect Body Surface Lipids Rich in Methylene-Interrupted Diene
摘要： To protect themselves, insects cover their bodies with what is called cuticular lipid. The cuticular lipid of American cockroach has a unique lipid content; the most abundant is a cis-alkadiene, cis, cis-6, 9-heptacosadiene amounting to about 70%, which is followed by a branched alkane 3-methylpentacosane. In order to clarify the structural features of the unique lipid composition below the critical temperature, the cuticular lipid was studied by Fourier Transform Infrared (FTIR) spectroscopy in combination with attenuated total reflection (ATR) sampling technique. The infrared spectra measured on an extracted lipid sample at 20°C suggested that the lipid keeps an appreciable level of conformational and lateral packing regularity, in spite of high cis-unsaturated lipid content and also a highly disordered condition around the methyl terminals and cis-olefin groups. The CH2 scissoring and the CH2 rocking regions showed the characteristics of the O⊥ subcell. The same characteristics were observed also by in-situ measurements on a forewing of American cockroach. Combining the spectral features of these bands and the physicochemical properties of each component, it can be inferred that saturated lipids form highly ordered domains within the liquid containing the cis, cis-diene as main component. For comparison, the cuticular lipid of male cricket, which consisted many different hydrocarbons including 15 percent of unsaturated hydrocarbons, showed a lower regularity both in the conformation and in the lateral packing of hydrocarbon chains. These results imply that not only the degree of cis-unsaturation but also the chemical structure diversity of hydrocarbons is the important factor to determine the physicochemical properties of cuticular lipid.
关键词： cuticular lipid,American cockroach,FTIR spectroscopy,lateral packing,methylene-interrupted diene,cis-unsaturated lipids,ATR sampling technique,hydrocarbon chains,conformational order
更新于2025-09-04 15:30:14
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Growth and surface structural study of tin oxide films on Ag(001)
摘要： Tin oxide was prepared by reactive deposition of Sn in an O2 atmosphere at both room temperature (RT) and high temperature (HT) at 573 K as well from one monolayer to ten monolayer film coverages. The grown films were studied at RT by a combination of x-ray photoemission spectroscopy (XPS), low energy electron diffraction (LEED) and ultraviolet photoemission spectroscopy (UPS). At RT, the coexistence of both SnO and SnO2 was confirmed by XPS and valence band data with more SnO being formed at higher coverage. However, only one oxidised phase of tin oxide mainly due to SnO2 was formed at HT for most of the coverage. Presence of SnO was also confirmed only at the highest coverage studied here for HT. A multidomain LEED pattern having square (1 × 1) domains at 30° to each other was reported for low coverage of tin oxide at RT, which with an increase in coverage, gives rise to diffused background confirming no ordered tin oxide was formed. The similar multi-domain structure was also noticed for HT growth from lower coverage up to 5 monolayer equivalent (MLE) coverage which then transformed into hexagonal multidomain LEED pattern for higher coverage confirming the presence of clear oxide phase, unlike the RT growth case.
关键词： Thin films,Low energy electron diffraction,Photoemission spectroscopy
更新于2025-09-04 15:30:14
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Incipient Anion Intercalation of HOPG Close to the Oxygen Evolution Potential. A Combined X-ray Photoemission and Raman Spectroscopy Study
摘要： In the present work we used two different electrochemical (EC) techniques, namely cyclic voltammetry (CV) and normal pulsed voltammetry (NPV), applied to a highly oriented pyrolytic graphite (HOPG) electrode for anion intercalation in two different aqueous electrolytes (i.e. perchloric and sulphuric acid). We performed comparative X-ray photoemission (XPS) and Raman spectroscopy studies at various EC potentials. The chemical analysis obtained by XPS and Raman, the latter applied in-situ and in real-time during the electrochemical processes, indicates that at oxygen evolution potential (i.e. before reaching the well-known intercalation stage potentials) the HOPG intercalation process is already active. These results suggest that the intercalated compound is efficiently obtained before reaching higher potentials, which usually cause a detriment of the graphite crystal.
关键词： HOPG,Raman spectroscopy,X-ray photoemission,anion intercalation,normal pulsed voltammetry,cyclic voltammetry
更新于2025-09-04 15:30:14
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Nanoparticles at Biomimetic Interfaces: A Combined Experimental and Simulation Study on Charged Gold Nanoparticles/Lipid Bilayers Interfaces
摘要： The poor understanding of the interaction of nanomaterials with biologically relevant interfaces is recognized as one of the major issues currently limiting the development of nanomedicine. The central purpose of this study is to compare experimental (Confocal Microscopy, Fluorescence Correlation Spectroscopy, X-ray Reflectivity) and computational (Molecular Dynamics simulations) results to thoroughly describe the interaction of cationic gold nanoparticles (AuNP) with mixed zwitterionic/anionic lipid membranes. The adhesion of AuNPs to the lipid membrane is investigated on different length scales from a structural and dynamical point of view; with this approach, a series of complex phenomena, spanning from lipid extraction, localized membrane disruption, lateral phase separation and slaved diffusion, are characterized and interpreted from a molecular level to macroscopic observations.
关键词： Nanoparticles,Gold Nanoparticles,Molecular Dynamics,X-ray Reflectivity,Fluorescence Correlation Spectroscopy,Lipid Bilayers,Biomimetic Interfaces,Confocal Microscopy
更新于2025-09-04 15:30:14
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Electronic structure of the polymer-cathode interface of an organic electroluminescent device investigated using operando hard x-ray photoelectron spectroscopy
摘要： The electronic structure of a polymer-cathode interface of an operating organic light-emitting diode (OLED) was directly investigated using hard X-ray photoelectron spectroscopy (HAXPES). The potential distribution pro?le of the light-emitting copolymer layer as a function of the depth under the Al/Ba cathode layer in the OLED depended on the bias voltage. We found that band bending occurred in the copolymer of 9,9-dioctyl?uorene (50%) and N-(4-(2-butyl)-phenyl)diphenylamine (F8-PFB) layer near the cathode at 0 V bias, while a linear potential distribution formed in the F8-PFB when a bias voltage was applied to the OLED. Direct observation of the built-in potential and that band bending formed in the F8-PFB layer in the operating OLED suggested that charges moved in the F8-PFB layer before electron injection from the cathode.
关键词： polymer-cathode interface,band bending,organic light-emitting diode,electronic structure,hard X-ray photoelectron spectroscopy
更新于2025-09-04 15:30:14
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Near-Infrared (NIR) Spectrometry as a Fast and Reliable Tool for Fat and Moisture Analyses in Olives
摘要： The evaluation of fat and moisture contents for olive fruits is crucial for both olive growers and olive oil processors. Reference methods, such as Soxhlet extraction, used for fat content determination in olive fruits are time- and solvent- consuming and labor intensive. Near-infrared (NIR) spectroscopy is proposed as a solution toward rapid and nondestructive analyses of olive fruit fat and moisture contents. In the present work, comparative studies of the fat and moisture quantification methods were performed on four cultivars (Arbosana, Arbequina, Chiquitita, and Koroneiki) during six different harvesting time points to determine the potential of NIR as an alternative methodology. The impact of olive paste crushing degree on NIR performance was also investigated using three different grid sizes (4, 6, and 8 mm) on a hammer mill, in addition to a blade crusher. Results indicate a satisfactory correlation between the reference Soxhlet and NIR methods with R2 = 0.995. A comparison study of moisture content was also done on NIR and the use of conventional oven with the R2 value of 0.995. The crushing blade produced higher values in both moisture and fat contents in comparison to the hammer mill. The evaluation indicates that when building a chemometric model, all crush sizes and blade sizes should be represented in the model for highest accuracy.
关键词： Soxhlet extraction,Near-infrared (NIR) spectroscopy,moisture content,olive fruit,fat content,chemometric model
更新于2025-09-04 15:30:14
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Atomic scale depletion region at one dimensional MoSe <sub/>2</sub> -WSe <sub/>2</sub> heterointerface
摘要： Lateral heterojunctions based on two dimensional (2D) transition metal dichalcogenides (TMDCs) potentially realize monolayer devices exploiting 2D electronic structures and the functions introduced by the presence of 1D heterointerfaces. Electronic structures of a lateral MoSe2-WSe2 junction have been unveiled using scanning tunneling microscopy and spectroscopy. A smooth and narrow depletion region exists despite a defect-rich heterointerface deviating from the preferred zigzag orientations of the TMDC lattice. From the characteristics of the depletion region, a high carrier concentration and high internal electric fields are inferred, offering to benefit designs of lateral TMDC devices.
关键词： depletion region,MoSe2-WSe2,heterointerface,scanning tunneling microscopy,scanning tunneling spectroscopy,TMDCs
更新于2025-09-04 15:30:14