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[ACS Symposium Series] Raman Spectroscopy in the Undergraduate Curriculum Volume 1305 || Research with Undergraduates at the Intersection of Chemistry and Art: Surface-Enhanced Raman Scattering Studies of Oil Paintings
摘要： Undergraduate students are provided increasingly the opportunity to explore Raman spectroscopy as a part of their physical and analytical chemistry courses. Here, we describe a new approach for engaging undergraduate students with Raman spectroscopy in the research lab setting. In particular, Wustholz at William & Mary and Svoboda at Colonial Williamsburg engage in productive collaboration wherein develop surface-enhanced Raman scattering (SERS)-based methods to identify fugitive pigments in art. In this chapter, we present several case studies that highlight the pedagogical journeys of student researchers working at the intersection of chemistry and art. We describe how this collaborative SERS research has led to discovery, innovation, and the professional development of undergraduates.
关键词： surface-enhanced Raman scattering,SERS,chemistry and art,undergraduate research,Raman spectroscopy,fugitive pigments
更新于2025-09-10 09:29:36
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Fundamental molecules of life are pigments which arose and co-evolved as a response to the thermodynamic imperative of dissipating the prevailing solar spectrum
摘要： The driving force behind the origin and evolution of life has been the thermodynamic imperative of increasing the entropy production of the biosphere through increasing the global solar photon dissipation rate. In the upper atmosphere of today, oxygen and ozone derived from life processes are performing the short-wavelength UV-C and UV-B dissipation. On Earth’s surface, water and organic pigments in water facilitate the near-UV and visible photon dissipation. The first organic pigments probably formed, absorbed, and dissipated at those photochemically active wavelengths in the UV-C and UV-B that could have reached Earth’s surface during the Archean. Proliferation of these pigments can be understood as an autocatalytic photochemical process obeying non-equilibrium thermodynamic directives related to increasing solar photon dissipation rate. Under these directives, organic pigments would have evolved over time to increase the global photon dissipation rate by (1) increasing the ratio of their effective photon cross sections to their physical size, (2) decreasing their electronic excited state lifetimes, (3) quenching radiative de-excitation channels (e.g., fluorescence), (4) covering ever more completely the prevailing solar spectrum, and (5) proliferating and dispersing to cover an ever greater surface area of Earth. From knowledge of the evolution of the spectrum of G-type stars, and considering the most probable history of the transparency of Earth’s atmosphere, we construct the most probable Earth surface solar spectrum as a function of time and compare this with the history of molecular absorption maxima obtained from the available data in the literature. This comparison supports the conjecture that many fundamental molecules of life are pigments which arose, proliferated, and co-evolved as a response to dissipating the solar spectrum, supports the thermodynamic dissipation theory for the origin of life, constrains models for Earth’s early atmosphere, and sheds some new light on the origin of photosynthesis.
关键词： photosynthesis,thermodynamic dissipation,UV-C,solar spectrum,UV-B,Archean,organic pigments,origin of life
更新于2025-09-09 09:28:46
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Pigment palette study of the XIX century plafond painting by Raman spectroscopy
摘要： Within the framework of the restoration painted plafond performed in the distemper technique at the first half of the 19th century were investigated by micro-Raman spectroscopy, UV photography, optical microscopy. One hundred and fifty artistic composition fragments samples were studied from the different parts of plafond. The presence of the following basic pigments: emerald green, Scheele’s green; ultramarine, indigo blue, azurites, vermilion, ferric oxide based pigments were observed. Lead white, calcite and gypsum were identified. It’s ownership of the author’s record is discussed. The places of pigments application in the author’s layer of painting were localized, basic and auxiliary materials were identified.
关键词： Raman spectroscopy,Pigments identification,Distemper,Wall painting
更新于2025-09-09 09:28:46
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Selection of Informative Spectral Bands for PLS Models to Estimate Foliar Chlorophyll Content Using Hyperspectral Reflectance
摘要： Partial least-squares (PLS) regression is a popular method for modeling chemical constituents from spectroscopic data and has been widely applied to retrieve leaf chemical components via hyperspectral remote sensing. However, one persistent challenge for applying the PLS regression is the selection of informative spectral bands among the vast array of acquired spectra. No consensus has been reached yet on how to select informative bands regardless of many techniques being proposed. In this paper, we have composited four individual data sets containing a total of 598 leaf samples from various species to evaluate four different band elimination/selection methods. Results revealed that the stepwise-PLS approach was optimal to estimate leaf chlorophyll content even under different spectral resolutions, from which informative bands were identified. Informative bands, in general, include bands inside the near-infrared (NIR), and in addition, one within the blue range and one within the red range. With such combinations, the PLS regression models meet the requirement for accurate leaf chlorophyll estimation. For most PLS regression models, their accuracies decreased with the reduction of spectral resolution, but the stepwise-PLS approach could consistently estimate the chlorophyll content at different spectral resolutions (with R2 ≥ 0.77 for resolutions < 20 nm). The findings, hence, provide valuable insights for selecting informative spectral bands for PLS analysis and lay a strong foundation for retrieving foliar biochemical content using hyperspectral remote sensing data.
关键词： Band selection,partial least squares (PLS),leaf pigments,hyperspectral reflectance
更新于2025-09-09 09:28:46
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Mix-&-Read Determination of Mercury(II) at Trace Levels with Hybrid Mesoporous Silica Materials Incorporating Fluorescent Probes by a Simple Mix-&-Load Technique
摘要： The synthesis, characterization, and application of mesoporous materials containing boron–dipyrromethene (BODIPY) moieties that allow the sensitive and selective detection of HgII in aqueous environments by fluorescence enhancement is reported. For this purpose, BODIPY dye I containing a thia-aza crown ether receptor as the fluorescent probe for the detection of HgII in aqueous environments is encapsulated into mesoporous materials to avoid self-quenching or aggregation in water. Determination of HgII is accomplished within a few seconds with high selectivity and sensitivity, reaching a limit of detection of 12 ppt. The determination of trace amounts of HgII in natural waters and in fish extracts is demonstrated by using our sensing material. The incorporation of the material into several m-PAD strips yields a portable, cheap, quick, and easy-to-handle tool for trace HgII analysis in water.
关键词： dyes/pigments,mercury,fluorescence,mesoporous materials,test strips
更新于2025-09-09 09:28:46
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Responses of Morphology, Gas Exchange, Photochemical Activity of Photosystem II, and Antioxidant Balance in Cyclocarya paliurus to Light Spectra
摘要： Light quality is a critical factor regulating photosynthetic capacity which directly affects the final yield of plants. Cyclocarya paliurus is a multiple function tree species and its leaves are widely used as tea production and ingredient in China. However, the effects of varying light quality on photosynthetic process and the photoprotective mechanisms remains unexplored in-depth. In this study, the biomass accumulation, morphology changes, photosynthetic capacity, stomata ultrastructure, pigments content, PSII activity, reactive oxygen species production, antioxidant enzymes, and phenolic content of C. paliurus plants under different light-emitting diodes (LED) light treatments were investigated to test a hypothesis that the difference in photosynthetic efficiency of C. paliurus plants under differential light quality is related to the degree of photoinhibition and the activation of photoprotection. We found that C. paliurus plants performed better under the treatments of WL (white light, 445 and 560 nm) and BL (blue light, 456 nm) than the treatment of GL (green light, 514 nm) and RL (red light, 653 nm). The better performances were characterized by higher values of photosynthetic capacity, total biomass, pigments content, specific leaf mass per area, seeding height increment, leaf thickness and palisade length. In contrast, plants under the treatments of GL and RL suffered significant photoinhibition but effectively developed photoprotective mechanisms. Results of this study provide not only some insights of the response mechanisms of plant photosynthesis to light quality but also a scientific basis for improving the cultivation of C. paliurus plantations.
关键词： PSII activity,Cyclocarya paliurus,antioxidant balance,morphology,light quality,pigments content
更新于2025-09-09 09:28:46
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SENSITIVITY TO ENVIRONMENTAL STRESS OF PRATA,JAPIRA AND VITóRIA BANANA CULTIVARS PROVEN BY CHLOROPHYLL a FLUORESCENCE
摘要： This study aimed to evaluate the physiological responses to environmental stress during pre- and post-harvest of the following banana cultivars: Prata (AAB), Japira (AAAB) and Vitoria (AAAB). Analyses were carried out on young plants at vegetative stage (daughter-plant) and adult plants at reproductive stage (mother-plant). The experimental design was completely randomized. In the in vivo pre-harvest analysis were used seven replications, in a factorial scheme (3x2x2), three cultivars and two stages (vegetative and reproductive) and two collection periods (March and June). For the analysis of post-harvest quality were used five replications in a factorial design (3x2x5), corresponding to three cultivars, two development stages and five periods of post-harvest analysis, carried out every two days from stage 4 of fruit ripening. The chlorophyll a fluorescence emission kinetics showed low photochemical performance of the three cultivars in June, a period characterized by lower temperatures and water deficit. Prata was the cultivar with the lowest tolerance to abiotic physiological behavior changes, which also reflected in fruit quality, because there was a change in physical and physicochemical parameters. Japira and Vitoria cultivars showed similar physiological responses in the pre- and post-harvest periods, according to their phylogenetic proximity. The total performance index, i.e., the conservation of energy absorbed by PSII up to the reduction of the final PSI acceptors (PItotal) and the di-malonic aldehyde (MDA) content were significantly higher in Japira and Vitoria cultivars compared to Prata cultivar in the reproductive phase. There was no significant change in the potential quantum efficiency of PSII (FV / FM = jP0) among the three cultivars. It was concluded that Japira and Vitoria cultivars showed greater plasticity to tolerate or even adapt to abiotic variations keeping higher fruit yield. PItotal is the most sensitive parameter during the banana life cycle and important tool for distinguishing different cultivars yields.
关键词： Chlorophyll fluorescence,Musa spp.,post-harvest quality,lipid peroxidation,pigments
更新于2025-09-04 15:30:14
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Novel codon 15 RHO gene mutation associated with retinitis pigmentosa
摘要： To describe, in a multimodal way, a new RHO gene mutation with lysine-for-asparagine substitution in autosomal dominant retinitis pigmentosa. Methods: Case report. Retrospective data analysis. Results: The mutation is located within codon 15 of exon 1 of the RHO gene. A single base-pair transversion lead to a specific lysine-for-asparagine substitution (Asn15Lys). Hypoacusis, myopia, dyschromatopsis and diffuse retinitis pigmentosa were detected. Detailed multimodal images for the posterior segment are presented. Conclusion: We present a new mutation with a specific substitution that may cause eye disease and which has not been described previously. There is no description of this variant in the genetic databases.
关键词： rod-cone dystrophy,retinal pigments,opsins,pigmentary retinopathy,tapetoretinal degeneration
更新于2025-09-04 15:30:14