| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Ali, Rabea A. M., et al.
(författare)
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Neoproterozoic and Cretaceous mantle oxidation states : Controls Chock for and heterogeneity through time
- 2020
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Ingår i: Lithos. - : Elsevier BV. - 0024-4937 .- 1872-6143. ; 356
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Tidskriftsartikel (refereegranskat)abstract
- To estimate the oxygen fugacity (fO(2)) of the Neoproterozoic and Cretaceous suprasubduction zone mantle, and to evaluate the possible secular changes in the upper mantle oxidation state, the compositions of spinel, olivine and orthopyroxene of Neoproterozoic (Egypt and Saudi Arabia) and late Cretaceous (Iran) mantle rocks were determined. For accurate estimation fO(2), spinel ferric iron was calculated after correcting the electron microprobe data using a set of spine! standards for which the ferric iron content was measured by Mossbauer spectroscopy. The Neoproterozoic samples record strongly heterogenous fO(2) values ranging from moderately oxidized (FMQ +0.54) to ultra-reduced (FMQ-4.73) for harzburgites, from highly oxidized (FMQ+1.49) to moderately reduced (FMQ-0.60) for dunites as well as one highly reduced (FMQ-1.61) value for chromitite. Such heterogeneity is not apparent in the late Cretaceous harzburgites that record fO(2) values ranging from slightly oxidized (FMQ +0.45) to moderately reduced (FMQ -0.85). The fO(2) of the Neoproterozoic forearc mantle is most easily explained by melt-mantle interaction and deep-mantle recycling, while that of the late Cretaceous forearc mantle can be attributed to variable degrees of melt-mantle interaction. The estimated fO(2 )values of Neoproterozoic/Cretaceous mantle unaffected by melt-rock interaction and deep-mantle recycling, and published values of Precambrian and Modern mantle suggest a consistent upper mantle oxidation state from Proterozoic to present day.
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| 3. |
- Bahrami, Danial, et al.
(författare)
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Impact of Electrical Current on Single GaAs Nanowire Structure
- 2021
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Ingår i: Physica Status Solidi (B) Basic Research. - : Wiley. - 0370-1972. ; 258:8
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Tidskriftsartikel (refereegranskat)abstract
- The impact of electrical current on the structure of single free-standing Be-doped GaAs nanowires grown on a Si 111 substrate is investigated. Single nanowires have been structurally analyzed by X-ray nanodiffraction using synchrotron radiation before and after the application of an electrical current. The conductivity measurements on single nanowires in their as-grown geometry have been realized via W-probes installed inside a dual-beam focused ion beam/scanning electron microscopy chamber. Comparing reciprocal space maps of the 111 Bragg reflection, extracted perpendicular to the nanowire growth axis before and after the conductivity measurement, the structural impact of the electrical current is evidenced, including deformation of the hexagonal nanowire cross section, tilting, and bending with respect to the substrate normal. For electrical current densities below 30 A mm−2, the induced changes in the reciprocal space maps are negligible. However, for a current density of 347 A mm−2, the diffraction pattern is completely distorted. The mean cross section of the illuminated nanowire volume is reconstructed from the reciprocal space maps before and after the application of electrical current. Interestingly, the elongation of two pairs of opposing side facets accompanied by shrinkage of the third pair of facets is found. The variations in the nanowire diameter, as well as their tilt and bending, are confirmed by scanning electron microscopy. To explain these findings, material melting due to Joule heating during voltage/current application accompanied by anisotropic deformations induced by the W-probe is suggested.
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| 4. |
- Delavar, Mohammad Amir, et al.
(författare)
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Soil salinity mapping by remote sensing south of Urmia Lake, Iran
- 2020
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Ingår i: Geoderma Regional. - : Elsevier. - 2352-0094. ; 22
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Tidskriftsartikel (refereegranskat)abstract
- Urmia Lake is a shallow terminal Lake located in northwest Iran and it is one of the largest permanent Lakes in the Middle East. In this study, the changes in soil salinity at Urmia Lake were investigated using satellite images and the oldest salinity map of the area over a period of 45 years from 1973 to 2018. The distribution of salinity in 2018 was estimated using the supervised classification by the nonlinear hybrid model of artificial multi-layered neural network-genetic algorithm model (ANN-GA) while the salinity map for the years of 1985, 1995, 2005 and 2015 was estimated by the unsupervised method. Further, the salinity data of surface soil in the region for the year 1973 was also digitized and utilized. For this purpose, 291 surface samples (258 samples for modeling and 33 samples for the re-evaluation of the model) of the studied region were collected and analyzed in 2018. The input neurons were selected by analyzing the satellite imagery bands, salinity indices, salinity ratio index and normalized difference vegetation index. The correlation coefficient and root-mean-square error of the training network model were equal to 0.94 and 0.04, respectively. The salinity map of the studied region was estimated using this model and classified into six classes (S0 to S5). The produced map of 2018 was used to re-evaluate the results. It showed that lower estimation accuracy was in classes S1 and S2. The obtained results in this study indicated that roughness, moisture, the density of halophyte plants and sodium slickspot were some of the sources for estimation of errors in lower salinity classes. The time-series changes in the salinity class of estimated maps showed that S3, S4 and S5 classes have expanded between 1973 and 2018. These are in agreement with the field observation and with the other scientific reports about the studied area.
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| 5. |
- Ghaderi Bafti, Alireza, et al.
(författare)
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Automated actual evapotranspiration estimation : Hybrid model of a novel attention based U-Net and metaheuristic optimization algorithms
- 2024
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Ingår i: Atmospheric Research. - 0169-8095. ; 297
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Tidskriftsartikel (refereegranskat)abstract
- Actual evapotranspiration (ETa) plays a crucial role in the water and energy cycles of the earth. An accurate estimate of the ETa is essential for management of the water resources, agriculture, and irrigation, as well as research on atmospheric variations. Despite the importance of accurate ETa values, estimating and mapping them remains challenging due to the physical and biological complexity of the ET process. As a novel approach for rapid and reliable estimation of ETa, the present study develops automated deep learning (AutoDL) models that incorporate a metaheuristic optimization algorithm for image processing, architectural design, and hyperparameter tuning. The proposed AutoDL models integrate three different spatial and channel attention mechanisms, including a novel activated spatial attention mechanism (ASPAM), with the U-Net architecture. Bypassing the need for meteorological inputs, the proposed framework uses Moderate Resolution Imaging Spectrometer (MODIS) products and Digital Elevation Model (DEM) data as inputs. To evaluate the performance of the models, they are applied to three study areas in the United States with various climatic characteristics. According to the results, during the spring and summer, when the target values have higher certainty, the estimations are highly promising, with R2 as high as 0.91 and MAPE as low as 6.40%. Furthermore, the proposed ASPAM module improves the accuracy of ETa estimations compared to attention gate (AG) and squeeze and excitation (SE) attention modules. The results also indicate that the MODIS raw products and derived vegetation and water indices can predict ETa within a reliable range of accuracy, with the addition of DEM data marginally enhancing the models' performance. The automatic workflow of this model makes it significantly easy to use, contributing to its applicability and generalizability for enhancing atmospheric research.
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| 6. |
- Ghobadi, Nader, et al.
(författare)
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Optical transitions and photocatalytic activity of NiSe films prepared by the chemical solution deposition method
- 2022
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Ingår i: The European Physical Journal Plus. - : SPRINGER HEIDELBERG. - 2190-5444. ; 137:6
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Tidskriftsartikel (refereegranskat)abstract
- In this work, nanostructured NiSe thin films were prepared by the chemical solution deposition method at different pH fixing the deposition time. The surface morphology, structural and semiconductor properties of such films were investigated utilizing different methodologies. It was found that slight changes in pH can influence the optical bandgap and structure of NiSe films. The results of Tauc's plot and the derivation of the ineffective thickness method were compared to estimate the optical bandgap energy and the transition index. Additionally, the Urbach energy was also assessed. The potential of the NiSe nanostructured samples as photocatalysts was evaluated by analyzing the decomposition of azoic Congo red dye under visible light radiation.
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| 7. |
- Habibi, Maryam, et al.
(författare)
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Corrosion resistance and surface microstructure of Mg 3 N 2 / SS thin films by plasma focus instrument
- 2022
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Ingår i: Microscopy research and technique (Print). - : Wiley. - 1059-910X .- 1097-0029. ; 85:8, s. 2880-2893
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Tidskriftsartikel (refereegranskat)abstract
- Utilizing a plasma focus (PF) instrument, magnesium nitride (Mg3 N2 ) thin films were synthesized on stainless steel substrates. Twenty five optimum focus shots at 8 cm distance from the anode tip were used to deposit the films at different angular positions regarded to the anode axis. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD) analyses were performed to assess the surface morphology and structural characteristics of Mg3 N2 films. Based on AFM images, these films were studied to understand the effect of angular position variation on their surfaces through morphological and fractal parameters. By increasing the angle, we verify that the grain size decreased from 130(0) nm to 75(5) nm and also the mean quadratic surface roughness of the films reduced in its average values from (28.97 ± 3.24) nm to (23.10 ± 1.34) nm. Power spectrum density analysis indicated that films become more self-affine at larger angles. Furthermore, the corrosion behavior of the films was investigated through a potentiodynamic polarization test in H2 SO4 solution. It was found that the ion energy and flux, varying with the angular positions from the anode tip, directly affected the nanostructured roughness and surface morphology of the samples. The electrochemical studies of films show that the uncoated sample presented the lowest corrosion resistance. The highest corrosion resistance was obtained for the sample deposited with 25 optimum shots and at 0° angular position reaching a reduction in the corrosion current density of almost 800 times compared to the pure stainless steel-304 substrate.
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| 8. |
- Rashid, Farhan Lafta, et al.
(författare)
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Advancements in Fresnel Lens Technology across Diverse Solar Energy Applications: A Comprehensive Review
- 2024
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 17:3
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Tidskriftsartikel (refereegranskat)abstract
- Concentration of solar energy may be obtained by reflection, refraction, or a combination of the two. The collectors of a reflection system are designed to concentrate the sun’s rays onto a photovoltaic cell or steam tube. Refractive lenses concentrate light by having it travel through the lens. The sun’s rays are partially reflected and then refracted via a hybrid technique. Hybrid focus techniques have the potential to maximize power output. Fresnel lenses are an efficient tool for concentrating solar energy, which may then be used in a variety of applications. Development of both imaging and non-imaging devices is occurring at this time. Larger acceptance angles, better concentration ratios with less volume and shorter focal length, greater optical efficiency, etc., are only some of the advantages of non-imaging systems over imaging ones. This study encompasses numerical, experimental, and numerical and experimental studies on the use of Fresnel lenses in various solar energy systems to present a comprehensive picture of current scientific achievements in this field. The framework, design criteria, progress, and difficulties are all dissected in detail. Accordingly, some recommendations for further studies are suggested.
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| 9. |
- Sadeghi, Mohammad, 1962-, et al.
(författare)
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Influence of ion implantation on corrosion resistance of the nickel over steel
- 2023
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Ingår i: Materials Science and Technology. - : TAYLOR & FRANCIS LTD. - 0267-0836 .- 1743-2847.
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Tidskriftsartikel (refereegranskat)abstract
- Nitrogen ions were implanted at different energies of 15, 30, 45 and 60 keV and with the flux of 10(17) N(+)cm(-2) inside the nickel layers that have been deposited on the 304 stainless steel using the electron gun method at room temperature. XRD patterns showed different crystalline phases of nickel nitride for the implanted samples. The surface morphology was extracted by MountainsMap software's using statistical data from AFM analysis. In addition, a potentiodynamic polarisation test was performed in a 3.5% NaCl solution to study the corrosion behaviour. These studies revealed that corrosion was directly related to the deposition parameters, mainly the implantation energy, modifying the surface so that the highest corrosion resistance was obtained for the sample implanted with 60 keV.
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