Sharif Digital Repository

Physiological and photobiochemical changes and growth in the heterotrophic strain Chlorella vulgaris g120 were studied during trophic conversion from heterotrophic to phototrophic growth regime. After the exposure of the Chlorella g120 culture to light, it revealed a significant activity of the electron transport (450–700 μmol e− m−2 s−1 as measured by chlorophyll fluorescence) and high PSII photochemical yield Fv/Fm between 0.7 and 0.8. Fast fluorescence induction kinetics showed that PSII electron acceptors in the plastoquinone pool remained partly oxidized, indicating no downregulation of PSII electron transport. The data further revealed that high photobiochemical activity is lost in... 

Spatial and temporal patterns of climatological seasonality, interannual variability, and phytoplankton phenology were estimated using satellite-derived ocean color chlorophyll-a data (Chl-a) 1998 to 2020 in the Persian Gulf from. Biogeography of phytoplankton seasonal and interannual climatology was determined using k-means multivariate clustering analysis applied on the Chl-a time-series data. As a result, two distinct regions were identified: one in the deep north and middle area (DZC) with a minimum value of Chl-a in April–July (0.62–0.76 mg m−3) and maximum in December–February (1.07–1.59 mg m−3), and the other in the north–west coastal areas and along the southwest-southern area (SZC)... 

Remotely sensed data inherently contain noise. The development of inverse modelling methods with a low sensitivity to noise is in demand for the estimation of geophysical variables from remotely sensed data. The Active Learning Method (ALM) is well known to have a low sensitivity to noise. For the first time, ALM was utilized for the inversion of radiative transfer calculations with the aim of estimating chlorophyll a (Chl a), coloured dissolved organic matter (CDOM), and suspended particulate matter (SPM) in the Caspian Sea using MERIS (MEdium Resolution Imaging Spectrometer) data. ALM training is straightforward and fast. The ALM inversion models revealed the most relevant variables and... 

All of the man-made objects and anthropogenic activities related to the oil industries in water bodies (e.g. drilling, equipment installation, construction of oil platfonns and especially oil spillages) have enviromnental impacts on water ecosystems. The assessment of oil field operations and oil platfonns impacts on water quality have become a necessity throughout the world. Phytoplanktons have the lowest trophic level in water enviromnent; therefore the life of all of the other marine animals is highly relevant to phytoplanktonic population. Hence it seems necessary to monitor the spatiotemporal effects of different activities and events, related to oil industries on phytoplanktons.... 

Photosynthesis includes capturing sunlight by an assembly of molecules, called chlorophylls, and directing the harvested energy in the form of electronic excitations to the reaction center. Here we report, using real-space density functional theory and time-dependent density functional theory together with GW calculations, the optical and electronic properties of the two main chlorophylls in green plants, namely, chlorophylls a and b. Furthermore, we estimate the dipole and primitive quadrupole electric moments of these molecules. We employ Casida's assignment ansatz to study the absorption spectra of the chlorophylls in the two main red and blue regions at various environments with... 

Due to the noise that is present in remote sensing data, a robust method to retrieve information is needed. In this study, the active learning method (ALM) is applied to spectral remote sensing reflectance data to retrieve in-water pigment. The heart of the ALM is a fuzzy interpolation method that is called the ink drop spread (IDS). Three datasets (SeaBAM, synthetic and NOMAD) are used for the evaluation of the selected ALM approach. Comparison of the ALM with the ocean colour 4 (OC4) algorithm and the artificial neural network (ANN) algorithm demonstrated the robustness of the ALM approach in retrieval of in-water constituents from remote sensing reflectance data. In addition, the ALM... 

Monthly mean satellite derived Chl-a, aerosols, wind, SST, PAR, and turbidity datasets were used to investigate the possible factors regulating phytoplankton variability in the Persian Gulf. The spatial correlation analysis revealed two distinct regions of SST and PAR, and a relatively uniform spatial correlation pattern of the other parameters. The cross correlation between aeolian dusts and Chl-a was significantly positive with 1–3 months offset. The pattern of spatial correlation between Chl-a and SST was positive in the shallow regions without time lag, and was negative with time offset of 3–5 months in deeper regions. The cross correlation between Chl-a and north-ward winds were... 

The development of inexpensive, equipment-free, portable, and user/environmentally-friendly analytical devices that can be efficiently utilized for on-site detection of PA is still a great challenge. To address these unmet demands, we have developed a smartphone-based disposable sensing bioplatform through immobilization of chlorophyll in a cotton thread for fluorescent monitoring of picric acid (PA). The fluorescence quenching of chlorophyll upon increasing the PA concentration based on the inner filter effect was considered as the sensing strategy in the developed sensor. The fabricated thread-based microfluidic sensing bioplatform was further coupled with a compact, low cost, portable,... 

In this article, indium doped ZnO nanoparticles (alloy nanoparticles) were investigated as inhibitors against algae growth on adobe mud and earthen artworks for surface preservation from destruction caused by micro-organisms under humid conditions, through surface modification and activation run off. Nanoparticles (NPs) were fabricated by physical vapor deposition (PVD) growth mechanism. The fabricated NPs were approximately 20 nm in size. The Chlorella vulgaris and Scenedesmus quadricauda were tested by application of indium doped ZnO nanoparticles (In/ZnO NPs) as inhibitors. As concentrations of NPs increased, the negative impacts of NPs on the algal growth were enhanced and physical...