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Photocatalytic removal of phenanthrene and algae by a novel Ca-Ag3PO4 composite under visible light: Reactivity and coexisting effect
摘要： In this study, the feasibility of a novel Ca-Ag3PO4 composite with visible light irradiation for the phenanthrene (PHE) degradation and algae inactivation in artificial seawater was firstly investigated. The experimental findings revealed that Ag3PO4 phase was sucessfully formed on the Ca-based material, and the presence of Ca-based material could effectively keep Ag3PO4 particles stable. An excellent performance on PHE degradation or algae inactivation was observed from Ca-Ag3PO4 composite under visible light irradiation. The degradation of PHE or inactivation of algae not only could be efficiently achieved in the single mode, but also could be successfully achieved in the coexisting mode. Above 96 % of PHE and algae were simultaneously removed within 12 h in the Ca-Ag3PO4/visible light system. It was further observed that the degradation of PHE and/or inactivation of algae increased with the increase of Ca-Ag3PO4 dosage. HO? was the primary radical responsible for PHE degradation, whereas HO? and Ag+ released from Ca-Ag3PO4 mainly contributed to the algae inactivation. A possible mechanism involving the catalytic removal of PHE and algae by Ca-Ag3PO4 under visible light irradiation was proposed. This study provides helpful guide for the simultaneous removal of various pollutants in real seawater.
关键词： Ag3PO4,Algae,Photocatalytic,Advanced oxidation processes (AOPs),Visible light,Phenanthrene (PHE)
更新于2025-09-23 15:23:52
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Analyzing carotenoids of snow algae by Raman microspectroscopy and high-performance liquid chromatography
摘要： We tested the potential of Raman microspectroscopy to determine carotenoid pigments — both primary (lutein, beta-carotene) and secondary (astaxanthin) carotenoids — in the different species and life-cycle stages of snow algae from the order Chlamydomonadales (Chlorophyta). We compared the performance of Raman spectrometry to a reference method of biological pigment analysis, high-performance liquid chromatography (HPLC). The three main carotenoid Raman bands of the astaxanthin-rich red cysts were located at 1520, 1156 and 1006 cm-1. The shifts (orange aplanozygotes and green motile cells with flagella) in the position of the ν1(C=C) Raman band of the polyenic chain is consistent with the expected changes in the ratios of the various carotenoid pigments. Flagellated green cells commonly contain lutein as a major carotenoid, together with minor amounts of β-carotene and varying amounts of antheraxanthin, violaxanthin and neoxanthin. Aplanozygotes contain mixtures of both primary and secondary carotenoids. In most cases, the ν1(C=C) band is an overlapping set of bands, which is due to the signal of all carotenoid pigments in the sample, and a deconvolution along with the band position shifts (mainly ν1) could be used to characterize the mixture of carotenoids. However, the ability of Raman spectroscopy to discriminate between structurally slightly differing carotenoid pigments or several carotenoids in an admixture in an unknown biological system remains limited.
关键词： HPLC,Snow algae,Biomarker,Raman spectroscopy,Exobiology,Carotenoids
更新于2025-09-23 15:22:29
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FVI—A Floating Vegetation Index Formed with Three Near-IR Channels in the 1.0–1.24 μm Spectral Range for the Detection of Vegetation Floating over Water Surfaces
摘要： Through the analysis of hyperspectral imaging data collected over water surfaces covered by floating vegetation, such as Sargassum and algae, we observed that the spectra commonly contain a reflectance peak centered near 1.07 μm. This peak results from the competing effects between the well-known vegetation reflectance plateau in the 0.81–1.3 μm spectral range and the absorption effects above 0.75 μm by liquid water within the vegetation and in the surrounding water bodies. In this article, we propose a new index, namely the floating vegetation index (FVI), for the hyperspectral remote sensing of vegetation over surface layers of oceans and inland lakes. In the formulation of the FVI, one channel centered near 1.0 μm and another 1.24 μm are used to form a linear baseline. The reflectance value of the third channel centered at the 1.07-μm reflectance peak above the baseline is defined as the FVI. Hyperspectral imaging data acquired with the AVIRIS (Airborne Visible Infrared Imaging Spectrometer) instrument over the Gulf of Mexico and over salt ponds near Moffett Field in southern portions of the San Francisco Bay were used to demonstrate the success in detecting Sargassum and floating algae with this index. It is expected that the use of this index for the global detection of floating vegetation from hyperspectral imaging data to be acquired with future satellite sensors will result in improved detection and therefore enhanced capability in estimating primary production, a measure of how much carbon is fixed per unit area per day by oceans and inland lakes.
关键词： Sargassum,sensors,remote sensing,hyperspectrum,vegetation index,algae
更新于2025-09-23 15:22:29
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Nanoparticle TiO2 size and rutile content impact bioconcentration and biomagnification from algae to daphnia
摘要： Little information is available about effect of particle size and crystal structure of nTiO2 on their trophic transfer. In this study, 5 nm anatase, 10 nm anatase, 100 nm anatase, 20 nm P25 (80% anatase and 20% rutile), and 25 nm rutile nTiO2 were selected to investigate the effects of size and crystal structure on the toxicity, bioconcentration, and trophic transfer of nTiO2 to algae and daphnia. In the exposed daphnids, metabolic pathways affected by nTiO2 and nTiO2-exposed algae (nTiO2-algae) were also explored. The 96 h IC50 values of algae and the 48 h LC50 values of daphnia were 10.3, 18.9, 43.9, 33.6, 65.4 mg/L and 10.5, 13.2, 37.0, 28.4, 60.7 mg/L, respectively, after exposed to nTiO2-5A, nTiO2-10A, nTiO2-100A, nTiO2-P25, and nTiO2-25R, respectively. The bioconcentration factors (BCFs) for 0.1, 1, and 10 mg/L nTiO2 in daphnia ranged from 21,220 L/kg to 145,350 L/kg. The nTiO2 biomagnification factors (BMFs) of daphnia fed with 1 and 10 mg/L nTiO2-exposed algae were consistently greater than 1.0 (5.7-122). The results show that the acute toxicity, BCF, and BMF all decreased with increasing size or rutile content of nTiO2. All types of nTiO2 were largely accumulated in the daphnia gut and were not completely depurated within 24 h. At the molecular level, 22 Kyoto Encyclopedia of Genes and Genomes (KEGG) metabolic pathways of daphnia were impacted by the nTiO2 and nTiO2-algae treatments, including glutathione metabolism, aminoacyl-tRNA biosynthesis, among others. Six and four KEGG metabolic pathways were significantly disturbed in daphnids exposed to nTiO2 and nTiO2-algae, respectively, indicating the presence of algae partially alleviated the negative impact of nTiO2 on metabolism. These findings increase understanding of the impacts of physicochemical properties of nTiO2 on the food chain from molecular scale to that of the whole organism, and provide new insight into the ecological effect of nanomaterials.
关键词： Trophic transfer,Bioaccumulation,Algae,Nanomaterial,Water flea
更新于2025-09-23 15:22:29
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Effect of LED Wavelengths and Light-Dark Cycle on Photosynthetic Production of <i>Chlorella Kessleri</i> for Algae-Based Biosensor Optimization
摘要： Observation of cell culture with a micro sensor system for biomedical application in measuring chemical, biological and physical parameters are widely used to evaluate cell metabolism respiration. Cellular respiration depicts the energy formation and molecules in the form of dissolved oxygen (pO2) level needed in the photosynthesis process. This paper presents the observation of pO2 level produced from the algae chlorella kessleri influenced by LED light source at wavelength of 480 nm (blue) and 650 nm (red). It aims to show the relationship between photosynthesis production activities to the signals produced by each condition for biosensor optimization. Artificial light settings consist of light-dark cycle to simulate a day light period in producing chlorophyll and night period as a time of relaxation. Sample of 150μL chlorella kessleri with density 1.4?106 cell/ml is immobilized in biochip-C and stimulate with two difference wavelength light sources for 30 minutes period ON/OFF. The result shows that the red light has 18% pO2 level higher than blue light since the algae is sensitive to the red light and absorbed more energy to produce chlorophyll.
关键词： algae-based biosensor,Chlorella Kessleri,light-dark cycle,photosynthetic production,LED wavelengths
更新于2025-09-19 17:13:59
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Quantitative analysis of cadmium and zinc in algae using laser-induced breakdown spectroscopy
摘要： In the demand for renewable energy sources, algae are considered to have a good potential for biodiesel production. Fast detection of heavy metals in energetic algae is of vital importance for algal biomass and biodiesel production environment monitoring. This study aims to determine cadmium (Cd) and zinc (Zn) contents in algal pellets with laser-induced breakdown spectroscopy (LIBS) technology. Partial least squares (PLS) regression and extreme learning machine (ELM) were constructed after spectral preprocessing by standard normal variate transformation (SNV), multiplicative scatter correction (MSC) and Savitzky–Golay smoothing (SG). For univariate analysis, ELM models based on Cd II 226.45 nm and Zn II 206.19 nm of SNV preprocessed spectra achieved the best results for Cd and Zn content prediction respectively, with Rp, RMSEP and RPD values of 0.9866, 50.71 mg kg?1 and 6.95 for the former, and 0.9873, 30.08 mg kg?1 and 6.44 for the latter. Multivariate analysis of Cd based on the PLS model with global spectra achieved the best performance with Rc and Rp values of 0.9965 and 0.9972, RMSECV and RMSEP values of 25.57 mg kg?1 and 23.63 mg kg?1, and an RPD value as high as 13.27, showing the excellent robustness and effectiveness of the model for Cd detection. For Zn analysis, the best performance was achieved by the ELM model based on feature variables selected by regression coefficients, with Rc and Rp values of 0.9836 and 0.9920, RMSEC and RMSEP values of 34.25 mg kg?1 and 24.64 mg kg?1, and an RPD value of 7.87. The results indicated that the LIBS technique combined with appropriate preprocessing algorithms and multivariate chemometric methods could be a rapid and accurate way for quantitative analysis of Cd and Zn contents in algae and the aquatic environment.
关键词： laser-induced breakdown spectroscopy,quantitative analysis,chemometric methods,zinc,algae,cadmium
更新于2025-09-12 10:27:22
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Fabrication of Optimized Eco-friendly Dye-Sensitized Solar Cells by Extracting Pigments from Low-Cost Native Wild Plants
摘要： The major proportion of dye-sensitized solar cells (DSSCs) fabrication cost is attributed to the pigments. In this study, to increase the performance/cost ratio of DSSCs, we used several wild regional plants of Persian Gulf zone for natural pigment production. At first, the optimum conditions for pigment extraction were obtained for all plants using response surface methodology. The results showed that increasing temperature, as well as extraction time, increased the pigment extraction efficiency while the pH of the solution did not exert a significant effect on the extraction process. Besides, the microwave-assisted method and pure ethanol have the highest extraction efficiency compared to ordinary solvent extraction and water as the extraction method and solvent, respectively. Moreover, all pigments were characterized using circular dichroism, dynamic light scattering, and zeta potential techniques. The results showed that the extracted pigments from Malva verticillata have the highest optical activity while all kinds of pigments tend to make aggregates 12 h after the extraction. Finally, the effectiveness of each pigment was evaluated as a sensitizer in natural DSSCs that fabricated using the doctor blade technique. Based on the photovoltaic results of the DSSCs sensitized with extracted pigments, the open circuit voltage and short circuit current ranged from 0.35 to 0.542 ??and 0.802 to 1.702 ????, respectively. The Microwave-assisted Malva verticillata-DSSC owned the highest energy conversion efficiency of 1.702% as well as the comparable open circuit voltage to that of the reference DSSC that made using synthetic sensitizer. This superiority could be attributed to the highest pigments concentration as well as the highest pigments optical activity of Malva verticillata. Moreover, the results showed that the LUMO energy level and the band gap of the extracted pigments from Malva verticillata are better than the other natural pigments for DSSC fabrication. Besides, due to the presence of carbonyl and hydroxyl groups in chemical structures of extracted pigment from Malva verticillata, an effective bond between the pigment and TiO2 surface might be achieved and thereby increasing the energy conversion efficiency.
关键词： solar cell,sensitizer,natural,Algae,pigment,Malva verticillata
更新于2025-09-11 14:15:04
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Potential of Landsat-Oli for Seagrass and Algae Species Detection and Discrimination in Bahrain National Water Using Spectral Reflectance
摘要： Seagrass (Halodule uninervis and Halophila stipulacea) and algae (green and brown) species are widely distributed along the coastal zones of the Bahrain national water. In this study the potential of Landsat-OLI VNIR spectral bands was investigated for distinction and discrimination among these species using spectral reflectances. The measured spectra’s of each species considering different coverage rate (0, 10, 30, 75 and 100%) were transformed using continuum-removed (CR) approach, resampled and convolved in the solar-reflective spectral bands of OLI using a radiative transfer code, then converted to water vegetation indices (WVI). Regression analysis were performed between the transformed WVI and the coverage rates of each species individually (seagrass and algae) and mixed; as well between WVI and NIR reflectances. Spectral and CR analyses showed that the blue and the green bands perform better than the coastal and the red bands for seagrass and algae classes’ discrimination. This result was further corroborated by the WVI. Regression results between the coverage rates and WVI calculated with green and NIR bands showed that the TDAVI and WAVI discriminate significantly among the mixed species (R2 of 0.70), and between individual species (R2 of 0.80 for algae and for seagrass). Accomplished between WVI and NIR reflectances, regression correlations were more significant when all mixed samples (R2 of 0.95) have been considered, likewise when we consider individually the two seagrass (R2 of 0.95) and the two algae species (R2 of 0.82).
关键词： Bahrain,Algae,Seagrass,Spectral signature,Landsat-OLI,Water vegetation indices
更新于2025-09-11 14:15:04
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Raman Spectroscopy and Applications || Raman Mapping: Emerging Applications
摘要： Raman mapping is a noninvasive, label‐free technique with high chemical specificity and high potential to become a leading method in biological and biomedical applications. As opposed to Raman spectroscopy, which provides discrete chemical information at distinct positions within the sample, Raman mapping provides chemical information coupled with spatial information. The laser spot scans the investigated sample area with a preset step size and acquires Raman spectra pixel by pixel. The Raman spectra are then discriminated from each other by chemometric analysis, and the end result is a false color map, an image of the sample that contains highly precise structural and chemical information. Raman imaging has been successfully used for label‐free investigations at cellular and subcellular level. Cell compartments, cell responses to drugs and different stages of the cell cycle from the stem cell to the completely differentiated cell were successfully distinguished. This technique is also able to differentiate between healthy and cancer cells, indicating great potential for replacing conventional cancer detection tools with Raman detection in the future.
关键词： plants,algae,cells,medical diagnosis,tissues,Raman imaging,Raman mapping,Raman spectroscopy
更新于2025-09-04 15:30:14