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Correlation of bio-optical properties with photosynthetic pigment and microorganism distribution in microbial mats from Hamelin Pool, Australia
摘要： Microbial mats and stromatolites are widespread in Hamelin Pool, Shark Bay, however the phototrophic capacity of these systems is unknown. This study has determined the optical properties and light-harvesting potential of these mats with light microsensors. These characteristics were linked via a combination of 16S rDNA sequencing, pigment analyses, and hyperspectral imaging. Local scalar irradiance was elevated over the incident down-welling irradiance by 1.5-fold, suggesting light trapping and strong scattering by the mats. Visible light (400-700 nm) penetrated to a depth of 2 mm, whereas near infrared light (700-800 nm) penetrated to at least 6 mm. Chlorophyll a and bacteriochlorophyll a (Bchl a) were found to be the dominant photosynthetic pigments present, with BChl a peaking at the subsurface (2-4 mm). Detailed 16S rDNA analyses revealed the presence of putative Chl f-containing Halomicronema sp. and photosynthetic members primarily decreased from the mat surface down to a depth of 6 mm. Data indicated high abundances of some pigments and phototrophic organisms in deeper layers of the mats (6-16 mm). It is proposed that the photosynthetic bacteria present in this system undergo unique adaptations to lower light conditions below the mat surface, and that phototrophic metabolisms are major contributors to ecosystem function.
关键词： chlorophyll,phototrophy,microbial mats,Hamelin Pool,pigments,stromatolite
更新于2025-09-23 15:21:01
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Redox-Switchable Cyan Fluorescence of a BODIPY Analog Inspired by Propentdyopent Pigments
摘要： The combination of reversible redox chemistry and bright redox-responsive emission properties is key to the development of electrofluorochromic switches for applications in bioimaging and optoelectronics. Herein, the redox-active dipyrrin-1,9-dione fragment, which is characteristic of the propentdyopent family of heme metabolites and urinary pigments, is employed for the synthesis of a BODIPY analog. This boron difluoride complex exhibits bright fluorescence in organic solvents and a significant ipsochromic shift to the cyan region when compared to typical green BODIPY dyes. Electrochemical and spectroscopic measurements show that the dipyrrindione ligand acts as an electron reservoir by hosting an unpaired spin upon one-electron reduction. This ligand-based redox event reversibly abolishes the fluorescence emission, thus switching off the novel electrofluorochromic system.
关键词： Redox chemistry,Switches,BODIPY,Fluorescence,Dyes/Pigments
更新于2025-09-23 15:21:01
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Microwave assisted synthesis of boron and nitrogen rich graphitic quantum dots to enhance fluorescence of photosynthetic pigments
摘要： Energy transfer between quantum dots and biomolecules is of interest due to high absorption capacity and high quantum efficiency of quantum dots. Amongst all types of quantum dots, graphene and graphitic quantum dots have great potential for energy transfer studies due to their high biocompatibility and low toxicity. In this study, a simple route to synthesize boron and nitrogen rich graphitic quantum dots (C-BN) and boron carbon nitride (BCN) quantum dots is demonstrated. Quantum dots were synthesized in a domestic microwave oven. Composition of quantum dots was controlled by tuning initial mole ratio of boron and nitrogen precursors. As molar ratio of boron precursor was increased, formation of C-BN quantum dots was favoured. C-BN quantum dots were mainly composed of boron and nitrogen (with around 10 % carbon) in their main composition, and sized around 2 nm with bright photoluminescence. To the best of our knowledge, this is the first study which proposes a bottom-up synthesis method to synthesize C-BN quantum dots based on domestic microwaves. Also, treating photosynthetic pigments with quantum dots resulted in 20 % enhancement of fluorescence of photosynthetic pigments at 670 nm, which demonstrates that C-BN and BCN quantum dots can be important constituents of artificial antenna systems for photosynthetic organisms.
关键词： Photosynthetic pigments,Boron nitride,Energy transfer,Graphitic quantum dots
更新于2025-09-23 15:19:57
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Dye Engineered Perovskite Solar Cells under Accelerated Thermal Stress and Prolonged Light Exposure
摘要： Herein, the thermal and light stability enhancement of planar perovskite solar cells (PSCs) based on the approach of dye-sensitization of the titania compact layer with the triphenylamine-based metal-free organic (E)-3-(5-(4-(bis(2’,4’-dibutoxy-[1,1’-biphenyl]-4-yl) amino) phenyl) thiophen-2-yl)-2-cyanoacrylic acid (D35) dye is reported. The D35 molecule is chemically adsorbed via a bidentate anchor group upon the TiO2 underlayer. This enhances the power conversion efficiency of PSCs due to its well-established versatile role, offering facilitation of electron charge transfer to the anode while favoring the growth of robust and homogenous perovskite layers. However, its influence in the PSC performance seems to expand further. The stability experiments showed an enhanced endurance for the devices after the insertion of D35, not only in shelf-shield conditions but also after accelerated thermal tests and prolonged light exposure. This study confirms the plethoric role of dye sensitization strategy and its advantages to interfacial engineering via organic chromophores towards efficient and stable PSCs.
关键词： dyes/pigments,perovskite solar cells,titanium dioxide,perovskite phases,stability enhancement
更新于2025-09-23 15:19:57
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Multivariate analysis and laser-induced breakdown spectroscopy (LIBS): a new approach for the spatially resolved classification of modern art materials
摘要： The ever-increasing speed of exchange of ideas, information, and culture allows contemporary art to be in constant growth, especially concerning the choice of artistic materials. Their characterization is not only crucial for the study of artistic techniques but also for research into the stability of the material and, consequently, the best preservation practices. For this aim, an analytical method should have the advantages of not requiring sample preparation, performing superficial micro-analysis, and obtaining detailed spectral information. For this study, laser-induced breakdown spectroscopy (LIBS) was employed. It was used for the identification of modern paints composed of inorganic pigments and organic binders, such as acrylics, alkyds, and styrene-acrylics. Principal component analysis (PCA) was used to classify the different pure materials, above all, the polymeric binders. To distinguish the paint mixtures, whose LIBS spectral results were more complex due to the pigment/binder interaction, a statistical method recently employed in the cultural heritage field was chosen, namely, random decision forest (RDF). This methodology allows a reduction of the variance of the data, testing of different training data sets by cross-validation, an increase of the predictive power. Furthermore, for the first time, the distribution of different inorganic pigments and organic binder materials in an unknown sample was mapped and correctly classified using the developed RDF. This study represents the first approach for the classification of modern and contemporary materials using LIBS combined with two different multivariate analyses. Subsequent optimization of measurement parameters and data processing will be considered in order to extend its employment to other artistic materials and conservation treatments.
关键词： Laser-induced breakdown spectroscopy,Inorganic pigments,Random decision forest,Organic binders,Principal component analysis
更新于2025-09-23 15:19:57
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Photoelectric evaluation of dye-sensitized solar cells based on prodigiosin pigment derived from Serratia marcescens 11E
摘要： Prodigiosin, a natural pigment produced as a secondary metabolite by the non-photosynthetic bacterium Serratia marcescens, was tested as a sensitizer in dye-sensitized solar cells (DSSC). The strain S. marcescens 11E, which was isolated from a natural spring located in the northeastern Mexican state of Nuevo Leon, was cultivated on peanut oil broth 1% v/v, a culture medium which is known to enhance the production of prodigiosin. The resulting pigment was extracted with chloroform and identified as prodigiosin based on the spectroscopic and structural characteristics obtained by UV–Vis spectrophotometry along with FTIR and 1H-NMR spectroscopies. The initial absorbance decomposition test performed on the bacterial pigment demonstrated that prodigiosin exhibited high photostability after five days, while the photovoltaic performance test of the sensitized DSSC, resulted in an open voltage circuit of 560 mV, a current density of 0.096 mA/cm2, and efficiency of 0.032 %. Structurally, the DSSC consisted of a titanium dioxide (TiO2) photoanode sensitized with the pigment by direct adsorption, an electrolyte containing a redox pair I?/I3? and a cathode or counter electrode prepared from a carbon paste. Since the overproduction of prodigiosin can be easily achieved on a large scale through the rapid fermentation of agro-industrial residues throughout the year without the need to allocate surfaces for the cultivation of pigment-producing plants or wait for specific seasons for their cultivation, our results suggest that prodigiosin could be considered an excellent candidate to be used in the development of a low-tech, low-cost DSSC.
关键词： Low-cost DSSC,Solar energy,Bacterial pigments,Native strain
更新于2025-09-23 15:19:57
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Characterisation of Colour Components and Polymeric Pigments of Commercial Red Wines by Using Selected UV-Vis Spectrophotometric Methods
摘要： The composition of the colour components of commercial red wines from Italy was analysed in terms of total colour, co-pigmentation, SO2-resistant pigments, small and large polymeric pigments, and tannins. A total of 128 wines, including Sangiovese, Cabernet Sauvignon, Nero d’Avola, Merlot, Marzemino, Negroamaro, Aglianico, Cannonau and Rossese di dolceacqua from five vintages (1999 to 2003) were analysed. The composition of the wines showed significant differences in terms of total colour and co-pigmentation. Total colour at 520 nm was highest in Marzemino (7.50±1.5 AU, absorbance units), and then in Aglianico (7.10±2.8 AU) and Cabernet Sauvignon (5.01±2.50 AU). The level of large and small polymeric pigments in Sangiovese wines showed a range from 0.05 to 0.40 and 0.10 to 0.27 AU 520 nm respectively. The variation in the level of polymeric pigments is affected by a number of factors, including vintage, grape composition, fermentation and storage conditions.
关键词： wine,co-pigmentation,Sangiovese,tannins,polymeric pigments
更新于2025-09-19 17:15:36
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Design of Near Infrared Reflective Effective Pigment for LiDAR Detectable Paint
摘要： Light Detection and Ranging (LiDAR) is a primary sensor for autonomous vehicles to recognize surroundings. It detects near-infrared (NIR) light pulses, typically at 905nm, which is emitted and reflected by surrounding objects. Here, the fact of the matter is that conventional black or dark-tone cars with extremely low NIR reflection are hard to be detected by LiDAR and endanger the future highway. In this work, we propose to use platelet-shaped effect pigments with visible absorption and NIR reflectivity. Copper(Ⅱ) oxide and Silicon dioxide multilayer are theoretically investigated with different numbers of layers and thicknesses. The optimized structures appear various dark-tone colors with high NIR-reflectivity over 90%.
关键词： effect pigments,dark-tone colors,LiDAR,autonomous vehicles,NIR reflective
更新于2025-09-19 17:13:59
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Thermodynamics of Natural Pigment-Doped Ethanol under Monochromatic Laser Irradiation
摘要： A laser beam heats a mixture of ethanol and anthocyanins producing the effect of a reciprocating machine. This behaviour is analyzed in terms of the stable, metastable and unstable states of Landau and Lifschitz. Trying first with the van der Waals equation of state, with negative results because the system state is normally far from the critical state, a modified version, with van der Waals coefficients depending linearly on the temperature is proposed, based in the thermodynamic properties of ethanol at room and critical temperatures. The resulting theory allows us to understand the discontinuous results concerning the absorption of the laser beam in terms of a thermodynamic cycle and its frequency dependence on the laser light focus position. Slight changes in the experimental setup may enable the measurement of thermodynamic properties in metastable states.
关键词： Ethanol,van der Waals Equation,Laser Irradiation,Thermodynamics,Natural Pigments
更新于2025-09-16 10:30:52
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Investigation of Cell Growth and Chlorophyll a Content of the Coccolithophorid Alga Emiliania huxleyi by Using Simple Bench-Top Flow Cytometry
摘要： The coccolithophorid alga Emiliania huxleyi produces micro-structured calcite particles, which are called coccoliths. Due to their unique and sophisticated structure, coccoliths are highly promising for different industrial applications, such as paper manufacturing, color and lacquer preparation. The mass production of coccoliths requires the evaluation of optimum cultivation conditions. This study investigates the impact of varying irradiance (10-1500 μmol m-2 s-1) on growth and chlorophyll a content of two calcifying strains CCMP371 and RCC1216 as well as on the non-calcifying strain RCC1217 (haploid form of RCC1217). The light kinetics contradicts the popular opinion, that E. huxleyi is an extraordinarily light tolerating alga in general. Photoinhibition was already observed at irradiance >500 μmol m-2 s-1 in the case of the calcifying strains. Furthermore, light requirements to grow at maximum growth rate, as well as thresholds towards photoinhibition were considerably different between calcifying and non-calcifying strains. The haplont required significantly higher irradiance to reach maximum μspec (>200 μmol m-2 s-1), while being much more tolerant to towards photoinhibition, which occurred not until 800 μmol m-2 s-1. Furthermore, a novel method was proposed to allow for the estimation of chlorophyll a content from flow cytometry data. By comprising an Advanced Fluorescence Ratio (AFLR), which considers culture heterogeneity, this method enables for simple chlorophyll a estimation also in older cultures of calcifying Emiliania huxleyi, which tend to build agglomerates.
关键词： Autofluorescence,characterization,Photosynthetic pigments,Flow cytometry,Chlorophyll,Microalgae
更新于2025-09-16 10:30:52