摘要 :
The intent of ecological restoration is ambigu-ous, its circumscription as a discipline is vague,and its standards of practice have yet to be eluci-dated. Some restorationists assume that these questionsare merely quibbles, the re...
展开
The intent of ecological restoration is ambigu-ous, its circumscription as a discipline is vague,and its standards of practice have yet to be eluci-dated. Some restorationists assume that these questionsare merely quibbles, the resolution of which will becomeapparent after a sufficient lapse of time. This viewpointwas resolutely explained to me 20 years ago, and I've heardit expressed again this year.
收起
摘要 :
Creating sensitive and reproducible substrates for surface-enhanced Raman spectroscopy (SERS) has been a challenge in recent years. While SERS offers significant benefits over traditional Raman spectroscopy, certain hindrances hav...
展开
Creating sensitive and reproducible substrates for surface-enhanced Raman spectroscopy (SERS) has been a challenge in recent years. While SERS offers significant benefits over traditional Raman spectroscopy, certain hindrances have limited their commercial use, especially in settings where low limits of detection are necessary. We studied a variety of laser-deposited silver microstructured SERS substrates with different morphology as a means to optimize analyte detection. We found that using a 405 nm laser to deposit lines of silver nanoparticles (AgNPS) from a 2 mM silver nitrate and sodium citrate solution offered not only the best enhancement, but also the most consistent and reproducible substrates. We also found that the probability of deposition by laser was wavelength dependent and that longer wavelengths were less likely to deposit than shorter wavelengths. This work offers a better understanding of the laser deposition process as well as how substrate shape and structure effect SERS signals.
收起
摘要 :
Surface enhanced Raman spectroscopy has many advantages over its parent technique of Raman spectroscopy. Some of these advantages such as increased sensitivity and selectivity and therefore the possibility of small sample sizes an...
展开
Surface enhanced Raman spectroscopy has many advantages over its parent technique of Raman spectroscopy. Some of these advantages such as increased sensitivity and selectivity and therefore the possibility of small sample sizes and detection of small concentrations are invaluable in the field of forensics. A variety of new SERS surfaces and novel approaches are presented here on a wide range of forensically relevant topics. (C) 2018 Elsevier B.V. All rights reserved.
收起
摘要 :
Gold nanoparticles of triangular shape were bio-synthesized by reduction of aqueous chloroaurate ions in pelargonium plant extract. Optical properties and morphology of gold nanotriangles were analyzed by UV-VIS absorption spectro...
展开
Gold nanoparticles of triangular shape were bio-synthesized by reduction of aqueous chloroaurate ions in pelargonium plant extract. Optical properties and morphology of gold nanotriangles were analyzed by UV-VIS absorption spectroscopy, X-ray diffraction, Electron Diffraction and Transmission Electron Microscopy (TEM). The possibility of using as bio-synthesized gold nanotriangles in surface enhanced Raman scattering (SERS) applications was demonstrated with p-aminothiophenol as probe molecule. The biosynthesis method can be considered sale and ecological for nanomaterials fabrication.
收起
摘要 :
Surface-enhanced Raman scattering spectroscopy (SERS) is a powerful technique of vibrational spectroscopy based on the inelastic scattering of incident photons by molecular species. It has unique properties such as ultra-sensitivi...
展开
Surface-enhanced Raman scattering spectroscopy (SERS) is a powerful technique of vibrational spectroscopy based on the inelastic scattering of incident photons by molecular species. It has unique properties such as ultra-sensitivity, selectivity, non-destructivity, speed, and fingerprinting properties for analytical and sensing applications. This enables SERS to be widely used in real-world sample analysis and basic plasmonic mechanistic studies. However, the desirable properties of SERS are compromised by the high cost and low reproducibility of the signals. The development of multifunctional, stable and reusable nano-engineered SERS substrates is a viable solution to circumvent these drawbacks. Recently, plasmonic SERS active nano-substrates with various morphologies have attracted the attention of researchers due to promising properties such as the formation of dense hot spots, additional stability, tunable and controlled morphology, and surface functionalization. This comprehensive review focused on the current advances in the field of SERS active nanosubstrates suitable for the detection and quantification of anionic environmental pollutants. The common fabrication methods, including the techniques for morphological adjustments and surface modification, substrate categories, and the design of nanotechnologically fabricated plasmonic SERS substrates for anion detection are systematically presented. Here, the need for the design, synthesis, and functionalization of SERS nano-substrates for anions of great environmental importance is explained in detail. In addition, the broad categories of SERS nano-substrates, namely colloid-based SERS substrates and solid-support SERS substrates are discussed. Moreover, a brief discussion of SERS detection of certain anionic pollutants in the environment is presented. Finally, the prospects in the fabrication and commercialization of pilot-scale handheld SERS sensors and the construction of smart nano-substrates integrated with novel amplifying materials for the detection of anions of environmental and health concern are proposed.
收起
摘要 :
? 2022 Elsevier LtdNitroimidazoles are a family of veterinary drugs containing a 5-nitroimidazole ring structure, which are commonly used antibiotics. In view of their potential genotoxicity and possible coexistence in actual samp...
展开
? 2022 Elsevier LtdNitroimidazoles are a family of veterinary drugs containing a 5-nitroimidazole ring structure, which are commonly used antibiotics. In view of their potential genotoxicity and possible coexistence in actual samples, it is necessary to establish a rapid and effective method for the simultaneous determination of multiple nitroimidazoles. In this study, a rapid thin-layer chromatography combined with surface-enhanced Raman spectroscopy (TLC-SER) detection method for 14 nitroimidazole compounds has been established. The theoretical Raman spectra of the nitroimidazoles were calculated using the B3LYP/6-311+G(d) basis set in density functional theory (DFT) and the theoretical Raman spectra of TNZ, NBZ, ONZ, SCZ, DMZ, MNI, 2-HMZ, 4-HMZ, CMNI, IPZ, MNZ-OH and HMDMZ have been obtained for the first time. SERS detection was carried out on a gold nanoparticles (AuNPs) substrate, which exhibited strong SERS signals and a limit of detection limit of 0.1 mg/L. By optimizing the conditions used for the developing agent in TLC, 12 nitroimidazoles were successfully separated, while MNZ and RNZ still could not be separated. When combined with the chemometrics analysis method, the TLC-SERS method can realize the simultaneous detection of 14 nitroimidazoles. Actual pork samples were spiked with nitroimidazoles with a recovery rate of 80%–110% and RSD of 0.74%–16.70%, which showed that SERS and TLC-SERS methods are also effective for detection in actual samples. The detection time of this method is < 10 min, which is suitable for the rapid detection of nitroimidazoles, especially for the rapid qualitative identification of nitroimidazoles in situ.
收起
摘要 :
We report on the fabrication of highly uniform periodic arrays of metallic nanodots formed on glass substrates through a facile anodic aluminum oxide template-assisted process and their use in selective surface-enhanced Raman scat...
展开
We report on the fabrication of highly uniform periodic arrays of metallic nanodots formed on glass substrates through a facile anodic aluminum oxide template-assisted process and their use in selective surface-enhanced Raman scattering spectroscopy to probe the structural properties of flexible crystalline-silicon nanomembranes deposited on polymer substrates. A 14-fold enhancement in Raman scattering was observed from the thin flexible silicon membranes deposited on polyethylene terephthalate substrates, which were used to probe the internal strains in the silicon nanomembrane as a function of the bending radius.
收起
摘要 :
Although endocrine therapy is the most important treatment option in estrogen receptor (ER)-positive breast cancer, new strategies, such as molecular targeted agents together with endocrine therapy are required to improve survival...
展开
Although endocrine therapy is the most important treatment option in estrogen receptor (ER)-positive breast cancer, new strategies, such as molecular targeted agents together with endocrine therapy are required to improve survival. PIK3CA is the most frequent mutated gene in ER-positive early breast cancers, and PIK3CA mutation status is reported to affect activation of AKT and ERα. Moreover, recent studies demonstrate that patients had a better prognosis when tumors expressed ER, androgen receptor (AR), and vitamin D receptor (VDR). In this study, we examined expression of AR and VDR, phosphorylation of AKT serine (Ser) 473 (AKT phospho-Ser473) and ERα Ser167 (ERα phospho-Ser167) by immunohistochemistry in ER-positive, HER2-negative early breast cancer. PIK3CA gene mutations were also detected in genomic DNA extracted from tumor blocks. Correlations between these biological markers, clinicopathological factors and prognosis were analyzed. Levels of AKT phospho-Ser473 were significantly higher in premenopausal women than in postmenopausal women. In contrast, AR expression was significantly higher in postmenopausal women than in premenopausal women. PIK3CA mutations were detected in 47% in premenopausal women and 47% in postmenopausal women. Postmenopausal women with PIK3CA wild-type tumors had significantly worse disease-free survival than patients with PIK3CA mutant tumors. Low levels of AKT phospho-Ser473 and high levels of ERα phospho-Ser167 were strongly associated with increased disease-free survival in postmenopausal women. Evaluation of ERα activation, in addition to PIK3CA mutation status, might be helpful in identifying patients who are likely to benefit from endocrine therapy alone versus those who are not in postmenopausal ER-positive early breast cancer.
收起
摘要 :
Background: Food quality and safety are very important from health as well as fiscal point of view. Surfaceenhanced Raman spectroscopy (SERS) techniques have unique advantages in the field of food detection, with characteristics o...
展开
Background: Food quality and safety are very important from health as well as fiscal point of view. Surfaceenhanced Raman spectroscopy (SERS) techniques have unique advantages in the field of food detection, with characteristics of fast analysis speed, high detection sensitivity, and without interference from the water phase. Scope and approach: In this review, recent and potential advances in the application of SERS in food safety and quality from the perspective of SERS substrate and SERS composite systems are addressed. SERS systems such as molecular labeling, immunochromatographic assay, microfluidics, molecularly imprinted polymers, colorimetry and imaging are discussed, and their main advantages and limitations are highlighted. The applications of SERS in food safety are reviewed critically, with focus on the detection of microorganisms, pesticides, metal ions and antibiotics. Furthermore, applications of SERS in food quality regarding food freshness and ingredients are discussed.
收起
摘要 :
B-cell activating factor (BAFF) plays a role for the maturation and the maintenance of B cells. Lipopolysaccharide (LPS) activates toll-like receptor 4 (TLR4)-dependent signal transduction, which resulted in BAFF expression throug...
展开
B-cell activating factor (BAFF) plays a role for the maturation and the maintenance of B cells. Lipopolysaccharide (LPS) activates toll-like receptor 4 (TLR4)-dependent signal transduction, which resulted in BAFF expression through nuclear factor kappa B (NF-κB) activation. Here, we investigated whether BAFF expression could be regulated by p65 phosphorylation through the production of reactive oxygen species (ROS) or cyclic AMP (cAMP) in Raw264.7 murine macrophages. mBAFF expression was reduced by ROS scavengers and it was increased by dibutyl-cAMP, a cAMP analogue. mBAFF expression and mBAFF promoter activity were increased by co-transfection of p65 but they were reduced by p65-small interference (si) RNA. Serine (Ser) 276 phosphorylation of p65 was increased by LPS-mediated PKA activation or by the treatment with forskolin, adenylate cyclase activator and dibutyl-cAMP. In contrast, p65 phosphorylation at Ser276 was decreased by ROS scavengers. H2O2 increased intracellular cAMP concentration, significantly. While no increase in p65 phosphorylation at Ser276 was detected by the treatment with H_2O_2, CREB and p65 phosphorylation at Ser133 and Ser536 was observed, respectively. It implicates that p65 phosphorylation at Ser276 is independent of ROS-induced cAMP production. As another cAMP effector protein was cAMP-responsive guanine nucleotide exchange factor (Epac), a Rap GDP exchange factor, NF-κB was activated by the treatment with 8-(4-chloro-phenylthio)-2'-O-methyladenosine-3',5'-cyclic monophosphate (CPT) that is an activator to Epac. Epac1-mediated Rap1 was activated by the treatment with H2O2 but it was inhibited by ROS scavengers. CPT induced p65 phosphorylation at both Ser276 and Ser536. CPT also increased not only mBAFF expression but mBAFF promoter activity. Data demonstrate that TLR4-mediated mBAFF expression was resulted from the crosstalk of p65 phosphorylation at Ser536 and Ser276 through ROS- and/or cAMP-mediated signal transduction. It suggests for the first time that ROS/Epac1-mediated Rap1/NF-κB pathway could be required for BAFF expression.
收起
原文获取