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Photoconversion efficiency of Titania solar cells co-sensitized with natural pigments from cochineal, papaya peel and microalga Scenedesmus obliquus
摘要： Three natural pigments obtained from cochineal, papaya peel, and the microalga Scenedesmus obliquus were tested as sensitizers in dye sensitized Titania solar cells. The absorption characteristics of the pigments and the photoelectrochemical parameters were studied to determine the photoconversion efficiency of the cells. The interfacial charge transport processes present in the individually sensitized and the co-sensitized cells were determined by electrochemical impedance spectroscopy (EIS). The highest efficiencies achieved for individual pigments after testing a set of different concentrations were 0.228, 0.093 and 0.064% using cochineal, papaya peel extract and Scenedesmus obliquus extract respectively. 0.36% conversion efficiency was reached in the sensitized cell using a combination of the three pigments. The efficiency reached is in the range of those reported for natural pigments. Papaya peel extract and chlorophylls from Scenedesmus obliquus were examined for the first time as possible sensitizers in DSSC.
关键词： photoelectrochemical parameters,energy conversion efficiency.,natural pigments,DSSC,mixed extracts,electrochemical impedance spectroscopy (EIS)
更新于2025-09-12 10:27:22
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Effect of Different Combinations of Red and Blue LED Light on Growth Characteristics and Pigment Content of In Vitro Tomato Plantlets
摘要： The aim of this study was to evaluate the growth characteristics and pigment content of tomato plantlets grown under various ratios of red (R) (661 nm) and blue (B) (449 nm) LED light. In this study, three di?erent ratios of R and B (RB) light such as 5:01, 10:01, and 19:01 along with R (100%) were used. The photosynthetic photon ?ux density (PPFD), and photoperiod of the growth chamber was 120 ± 5 μmol m?2s?1 and 16/8 h (day/night), respectively. Tomato plantlets were cultured for six weeks in the growth chamber. It was shown that tomato plantlets had higher photosynthesis rate, higher pigments content, higher growth characteristics (e.g., number of leaves, leaf area, shoot number, root number, root length, dry, and fresh mass), and greater surviving rate under the R:B = 10:01 ratio among the treatments. The plantlets showed at least a threefold decrease in photosynthesis rate, as well as a signi?cant abnormal stem elongation when grown under 100% R light. It is concluded that the RB ratio of 10:01 showed excellent performance in all growth parameters. This result has shown that the optimum lighting environment improves tomato plantlet cultures in vitro.
关键词： tomato plantlets,pigments,light-emitting diode (LED),biomass,photosynthesis
更新于2025-09-12 10:27:22
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Molecular Engineering of Simple Metal‐Free Organic Dyes Derived from Triphenylamine for Dye‐Sensitized Solar Cell Applications
摘要： Two new metal-free organic sensitizers, L156 and L224, were designed, synthesized, and characterized for application in dye-sensitized solar cells (DSCs). The structures of the dyes contain a triphenylamine (TPA) segment and 4-(benzo[c][1,2,5]thiadiazol-4-yl)benzoic acid as electron-rich and -deficient moieties, respectively. Two different π bridges, thiophene and 4,8-bis(4-hexylphenyl)benzo[1,2-b:4,5-b’]dithiophene, were used for L156 and L224, respectively. The influence of iodide/triiodide, [Co(bpy)3]2+/3+ (bpy = 2,2’-bipyridine), and [Cu(tmby)2]2+/+ (tmby = 4,4’,6,6’-tetramethyl-2,2’-bipyridine) complexes as redox electrolytes and 18 NR-T and 30 NR-D transparent TiO2 films on the DSC device performance was investigated. The L156-based DSC with [Cu(tmby)2]2+/+ complexes as the redox electrolyte resulted in the best performance of 9.26 % and a remarkably high open-circuit voltage value of 1.1 V (1.096 V), with a short-circuit current of 12.2 mA cm?2 and a fill factor of 0.692, by using 30 NR-D TiO2 films. An efficiency of up to 21.9 % was achieved under a 1000 lx indoor light source, which proved that dye L156 was also an excellent candidate for indoor applications. The maximal monochromatic incident-photon-to-current conversion efficiency of L156–30 NR-D reached up to 70 %.
关键词： electrochemistry,donor–acceptor systems,dyes/pigments,sensitizers,solar cells
更新于2025-09-11 14:15:04
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Non‐invasive on‐site Raman study of polychrome and white enamelled glass artefacts in imitation of porcelain assigned to Bernard Perrot and his followers
摘要： Bernard Perrot produced sophisticated glass objects from ~1666–1709 in Orléans, particularly white enamelled artefacts and ruby glass. We present here the first non‐invasive Raman study of 16 polychrome and white enamelled glass artefacts that are assigned to Bernard Perrot or his followers. These glasses belong to the museum collections at Orléans and Sèvres in France. The prominent characteristic of these artefacts is their white bodies that were produced in imitation of porcelain. The small thickness of enamel applied to these glasses imposes the use of a high magnification (×200) long working distance microscope objective for Raman analysis. Pigments and opacifiers were identified, and the production technology was discussed. White opacification was found to be obtained by three compounds: calcium phosphate (bone opacification) for blown utensils, calcium antimonate for figurines, and cassiterite for thin enamels. The use of characteristic arsenic‐rich European cobalt was identified in the blue enamels with the characteristic Raman signature of lead arsenate apatite as observed for the 17th and 18th century French soft‐paste porcelains and Limoges enamels. The easy Raman detection of arsenic‐rich phases also allows on‐site identification of ruby glasses produced according to Perrot's technique (formation of Au° colloids by reaction initiated with an arsenic salt). The amount and crystallinity of calcium phosphate being variable appears to be a potential tool to discriminate between different production periods or workshops.
关键词： 17th century,porcelain,pigments,glass,enamels
更新于2025-09-11 14:15:04
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Using Polymers and Pigments to Produce Laser Interference Rings
摘要： When a laser of su?cient intensity is shined into a pigmented transparent medium, the partially absorbed laser light can heat and change the refractive index of the medium in the path of the beam. This altered medium will in turn cause the transmitted laser light to thermally defocus into a series of concentric rings. Some solvents such as 2-propanol and a variety of polymers such as polystyrene, polyethylene terephthalate, and polydimethylsiloxane can be pigmented with a variety of colors. Samples of various colors can be used to spectacularly demonstrate characteristics of light absorption. For example, a 2-propanol solution containing methyl red in red acidic form will absorb a green laser and produce interference rings, but a solution of methyl red in yellow basic form will not. As another example, a red laser beam will pass una?ected through a red pigmented ?lm, but the beam will heat a green ?lm (e.g., from a green pigmented polyethylene terephthalate soda bottle) to produce interference rings. Additionally, since the pattern produced is based on the interference of light waves, these demonstrations reinforce concepts associated with the wave nature of light.
关键词： Dyes/Pigments,Demonstrations,General Public,Analogies/Transfer,First-Year Undergraduate/General,Lasers
更新于2025-09-11 14:15:04
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Controlled aggregation of amphiphilic aggregation‐induced emission polycation and superparamagnetic iron oxide nanoparticles as fluorescence/magnetic resonance imaging probes
摘要： Fluorescence/magnetic resonance (MR) dual-mode imaging, which combines the excellent single-cell sensitivity of ?uorescence imaging and the high spatial resolution of MR imaging, has been applied to different biomedical applications. However, the aggregation-caused quenching characteristic of most ?uorescence molecules often put limits in their applications. Herein, a ?uorescence/MR dual-mode imaging probe [polyethylene glycol-polyethylenimine-tetraphenylethene (PEG-PEI-TPE)/superparamagnetic iron oxide (SPIO)] with aggregation-induced emission characteristic is prepared by coupling poly(acrylic acid)-coated SPIO with PEG-PEI-TPE. The ?uorescence intensity and lifetime of PEG-PEI-TPE/SPIO is higher than PEG-PEI-TPE especially at lower polymer concentrations (≤0.2 mg mL?1). Moreover, the ?uorescence intensity of PEG-PEI-TPE/SPIO gradually increased along with the decline of the pH from 9.0 to 4.0, which is bene?cial for studying intracellular organelles. The T2 relaxivity of PEG-PEI-TPE/SPIO is 212.3 Fe mM?1 s?1 under a 3.0 T MR scanner. Cell labeling experiment shows that PEG-PEI-TPE/SPIO can effectively label RAW 264.7 and Hela cells, and labeled cells are visible under both ?uorescence and clinical MR examinations.
关键词： composites,drug delivery systems,dyes/pigments,biomedical applications,self-assembly
更新于2025-09-11 14:15:04
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Marine coastal zones monitoring by shipborne semiautomatic passive optical complex
摘要： For studying of the environmental status of marine coastal areas, it is often necessary to obtain operatively detailed data about water constituents and their distribution over the area. The three-channel passive optical complex for Ecological Monitoring of Marine Areas (EMMA), developed by us, was applied in the Feodosia Bay, the Black Sea, to obtain remotely the absorption indices for the suspended matter, coloured dissolved organic matter, and phytoplankton pigments. It operated from board a vessel for more than 4 h and gave data for approximately 15,000 sea radiance coe?cient spectra. The obtained spectra were processed by the original method giving possibility to suppress negative in?uence of the weather and experiment conditions and to get the absorption index spectra of the water constituents. The data of shipborne remote sensing using EMMA were compared to the estimates retrieved from the measurements on water samples taken at special stations on the route; their correlation turned out to be quite reasonable. The distributions of the suspended matter and coloured organic matter, obtained remotely over the studied area, were discussed. This research showed the possibility of EMMA application for ground truth measurements and for exploring the sea areas close to the coastal line, which cannot be seen from satellites because of cloudiness.
关键词： phytoplankton pigments,coloured dissolved organic matter,marine coastal zones,suspended matter,absorption indices,monitoring,Black Sea,semiautomatic passive optical complex,EMMA,shipborne
更新于2025-09-11 14:12:44
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Synthesis of green cool pigments (CoxZn1-xO) for application in NIR radiation reflectance
摘要： Reconciling green synthesis, sustainability and production of pigments for protection of solar radiation is a continuous topic of search for unique, versatile and environmental compatible methods. In this perspective, we present the green synthesis of inorganic pigments with reflective properties of infrared radiation in the NIR region. Green powder pigments described by CoxZn1-xO, were obtained via the gelatinization method of starch colloidal suspension with inorganic salts (zinc and cobalt), calcined at different temperatures. Structural, morphological and spectroscopic characterization showed the pigments present Wurtzite crystalline phase with compact hexagonal structure, and monophasic when obtained at a calcination temperature above 800 °C. Colorimetric measurements obtained by the CIE-L*a*b* method presented values related to green pigments attributed to cobalt ions, which replace the zinc ions in the Wurtzite matrix and corroborate the composition estimated by X-ray fluorescence analysis for Co0.1Zn0.9O. The pigments' NIR reflectivity increased with the calcination temperature increasing, with R% > 35%; and when the pigment is dispersed in a white paint the increase is R% > 50%. Therefore, our green pigments present great potential to be used as an active material in cold coatings and in solar devices.
关键词： Colorimetry,NIR reflectance,Cool pigments,Green synthesis
更新于2025-09-10 09:29:36
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Coupling to Charge Transfer States Is the Key to Modulate the Optical Bands for Efficient Light-Harvesting in Purple Bacteria.
摘要： The photosynthetic apparatus of purple bacteria uses exciton delocalization and static disorder to modulate the position and broadening of its absorption bands, leading to efficient light harvesting. Its main antenna complex, LH2, contains two rings of identical bacteriochlorophyll pigments, B800 and B850, absorbing at 800 nm and at 850 nm, respectively. It has been an unsolved problem why static disorder of the strongly coupled B850 ring is several times larger than that of the B800 ring. Here we show that mixing between excitons and charge transfer states in the B850 ring is responsible for the effect. The linear absorption spectrum of the LH2 system is simulated by using a multi-scale approach with an exciton Hamiltonian generalized to include the charge transfer states that involve adjacent pigment pairs, with static disorder modelled microscopically by molecular dynamics simulations. Our results show that a sufficient inhomogeneous broadening of the B850 band, needed for efficient light-harvesting, is only obtained by utilizing static disorder in the coupling between local excited and inter-pigment charge transfer states.
关键词： exciton delocalization,B850,B800,charge transfer states,purple bacteria,LH2,molecular dynamics simulations,static disorder,bacteriochlorophyll pigments,photosynthetic apparatus,light harvesting
更新于2025-09-10 09:29:36
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Structural, Optical and Magnetic Properties of Ultramarine Pigments: A DFT Insight
摘要： The ultramarine pigments are among the most widely used coloring materials since the antiquity till present times. Despite many experimental studies, the characterization of ultramarines is still incomplete. In this work we reported for the first time the density functional theory results obtained for realistic periodic and large cluster models of ultramarines with blue S3- and yellow S2- chromophores. Periodic calculations provided insight into Sn- siting inside aluminosilicate cages, normally not resolved well in experimental structural data. All electron calculations performed on large cluster models showed that the optical properties of S3- ions depend little on their orientation within cavities, unless strong distortion from free S3- ion C2v symmetry is enforced by the lattice. No magnetic coupling between S3- species occupying adjacent cages was found. Upon the present results observed differences in the averaging of electron resonance signals should be rather ascribed to different S3- dynamical effects. Though the quantitative computational treatment of S2- systems is more challenging, due to near orbital degeneracy, the qualitative results show that the electronic structure and spectroscopic properties of embedded S2- radicals are more sensitive to the environment than in the case of S3- species.
关键词： S3- chromophores,density functional theory,S2- chromophores,magnetic properties,aluminosilicate cages,ultramarine pigments,optical properties
更新于2025-09-10 09:29:36