| 1. |
- Hamawandi, Bejan, PhD, et al.
(författare)
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A Comparative Study on the Thermoelectric Properties of Bismuth Chalcogenide Alloys Synthesized through Mechanochemical Alloying and Microwave-Assisted Solution Synthesis Routes
- 2020
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Ingår i: Frontiers in Materials. - : Frontiers Media S.A.. - 2296-8016. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- The way a material is synthesized and processed has an immense effect on its microstructure, which in turn has a big impact on its transport properties. Here, we compare the thermoelectric (TE) properties of n- and p-type Bi2−xSbxTe3 (x: 0 and 1.5) materials synthesized through two different routes, specifically mechanochemical alloying (MA)—as a solid-state synthesis route—and microwave(MW)-assisted polyol synthesis—as a solution synthesis route. Reaction time is significantly reduced in the MW synthesis, leading to significantly lower energy consumption (i.e., higher energy efficiency) per batch than using the MA route. The resultant materials are compared for their crystallinity, phase purity, morphology, and microstructure. Spark plasma sintering was used to prepare pellets, and the resultant consolidates were evaluated for their transport properties. TE properties and microstructure of the specimens were investigated in relation to processing conditions and composition. MA samples formed fused structures (from 200 nm to several micrometers in size) composed of smaller particles. MW-synthesized materials exhibited hexagonal platelet morphology, high crystallinity, and phase purity. They also showed lower thermal conductivity, leading to a higher resultant TE figure-of-merit ZT. TE properties of Bi2−xSbxTe3 samples were studied on sintered cylindrical pellet samples, where the highest ZT values achieved were 1.04 (at 440 K) for MW-Bi2Te3 and 0.76 (at 523 K) for MW-Bi0.5Sb1.5Te3 samples, while MA-Bi2Te3 and MA-Bi0.5Sb1.5Te3 samples showed maximum ZT values of 0.74 (at 460 K) and 0.27 (at 300 K), respectively, as n- and p-type TE materials. The observed trend is much higher ZT values for MW samples, ascribed to their higher degree of texturing and nanostructured grains reducing the thermal conductivity, thus achieving a better overall performance, verifying the prospect to enhance ZT using MW-assisted solution synthesis approach.
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| 2. |
- Messaoudi, O., et al.
(författare)
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Correlation between experimental and DFT calculations of photocatalytic and optical properties of La 0.8 Nd 0.1 Sr 0.1 MnO 3 perovskite: degradation efficiency of methyl orange dye under visible-irradiated conditions
- 2021
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Ingår i: Journal of Materials Science: Materials in Electronics. - : Springer Science and Business Media LLC. - 1573-482X .- 0957-4522. ; 32:17, s. 22481-22492
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Tidskriftsartikel (refereegranskat)abstract
- La0.8Nd0.1Sr0.1MnO3 perovskite was synthesized using the citrate gel method. The crystal structure was studied by X-ray diffraction. The Rietveld refinement reveals a single R-3C rhombohedral structure. The morphological properties were investigated by a scanning electron microscopy, connected to an energy-dispersive X-ray detector for mapping and elements composition, showing a sponge-like structure behavior of agglomerated particles. The band gap energy and the optical properties were studied theoretically by Density-Functional Theory (DFT) calculations. It showed that La0.8Nd0.1Sr0.1MnO3 exhibited a high photoabsorption property with band gap energy of ≈ 2.5 eV. The methyl orange (MO) degradation properties were studied by measuring time-dependent UV–Visible absorption of the dye solution. The photocatalytic activity was evaluated at different times under visible light and ambient temperature conditions for La0.8Nd0.1Sr0.1MnO3 solution. A high degradation rate of 80% in 120 min under UV irradiation conditions was observed. It indicated that La0.8Nd0.1Sr0.1MnO3 presents high photocatalytic efficiency and could be a good candidate for MO degradation.
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| 3. |
- Mansouri, Kamel, et al.
(författare)
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CERAPP : Collaborative Estrogen Receptor Activity Prediction Project
- 2016
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Ingår i: Journal of Environmental Health Perspectives. - : Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 124:7, s. 1023-1033
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Humans are exposed to thousands of man-made chemicals in the environment. Some chemicals mimic natural endocrine hormones and, thus, have the potential to be endocrine disruptors. Most of these chemicals have never been tested for their ability to interact with the estrogen receptor (ER). Risk assessors need tools to prioritize chemicals for evaluation in costly in vivo tests, for instance, within the U.S. EPA Endocrine Disruptor Screening Program. OBJECTIVES: We describe a large-scale modeling project called CERAPP (Collaborative Estrogen Receptor Activity Prediction Project) and demonstrate the efficacy of using predictive computational models trained on high-throughput screening data to evaluate thousands of chemicals for ER-related activity and prioritize them for further testing. METHODS: CERAPP combined multiple models developed in collaboration with 17 groups in the United States and Europe to predict ER activity of a common set of 32,464 chemical structures. Quantitative structure-activity relationship models and docking approaches were employed, mostly using a common training set of 1,677 chemical structures provided by the U.S. EPA, to build a total of 40 categorical and 8 continuous models for binding, agonist, and antagonist ER activity. All predictions were evaluated on a set of 7,522 chemicals curated from the literature. To overcome the limitations of single models, a consensus was built by weighting models on scores based on their evaluated accuracies. RESULTS: Individual model scores ranged from 0.69 to 0.85, showing high prediction reliabilities. Out of the 32,464 chemicals, the consensus model predicted 4,001 chemicals (12.3%) as high priority actives and 6,742 potential actives (20.8%) to be considered for further testing.CONCLUSION: This project demonstrated the possibility to screen large libraries of chemicals using a consensus of different in silico approaches. This concept will be applied in future projects related to other end points.
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| 4. |
- Carey, T., et al.
(författare)
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Fully inkjet-printed two-dimensional material field-effect heterojunctions for wearable and textile electronics
- 2017
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Fully printed wearable electronics based on two-dimensional (2D) material heterojunction structures also known as heterostructures, such as field-effect transistors, require robust and reproducible printed multi-layer stacks consisting of active channel, dielectric and conductive contact layers. Solution processing of graphite and other layered materials provides low-cost inks enabling printed electronic devices, for example by inkjet printing. However, the limited quality of the 2D-material inks, the complexity of the layered arrangement, and the lack of a dielectric 2D-material ink able to operate at room temperature, under strain and after several washing cycles has impeded the fabrication of electronic devices on textile with fully printed 2D heterostructures. Here we demonstrate fully inkjet-printed 2D-material active heterostructures with graphene and hexagonal-boron nitride (h-BN) inks, and use them to fabricate all inkjet-printed flexible and washable field-effect transistors on textile, reaching a field-effect mobility of ~91 cm2 V-1 s-1, at low voltage (<5 V). This enables fully inkjet-printed electronic circuits, such as reprogrammable volatile memory cells, complementary inverters and OR logic gates.
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| 5. |
- Mansouri, Zina, et al.
(författare)
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Hydro-Geochemistry and Groundwater Quality Assessment of Ouargla Basin, South of Algeria
- 2022
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Ingår i: Water. - : MDPI. - 2073-4441. ; 14:15
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Tidskriftsartikel (refereegranskat)abstract
- This study aims to evaluate the hydro-chemical characteristics of Ouargla, Algeria basin groundwaters harvested from the Mio Pliocene aquifer. The study covered 70 samples; the physical parameters, potential of hydrogen (pH), and electrical conductivity EC μS.cm−1 were determined in situ, using a multiparameter; the laboratory analysis included dry residuals DR (mg/L), calcium Ca2+ (mg/L), magnesium Mg2+ (mg/L), sodium Na+ (mg/L), potassium K+ (mg/L), bicarbonates HCO3− (mg/L), sulfates SO42− (mg/L), and chloride Cl− (mg/L). The piper diagram shows that the Ouargla basin ground waters divided into two facies, sodic chlorinated in 93% and sodic sulphated in 7% of samples. The United States Salinity Laboratory Staff (USSL) diagram was used to detect the suitability of groundwater in irrigation where the results show that the groundwater was classed into two classes, poor water (C4 S4) and bad water (C4 S4). Furthermore, indices such as the Kelly index (KI), sodium adsorption ratio (SAR), sodium solubility percentage (Na%), and magnesium hazards (MH) confirm the negative effect of groundwater on soil permeability in 96%, 80%, 89%, and 53% of samples. The permeability index (PI) shows that the analyzed samples were considered as doubtful (71%) and safe (29%), otherwise there is no risk related to residual sodium carbonate (RSC). The geo-spatial distribution of deferent indices shows that all the study area has poor groundwater for irrigation, except the south-west part, where the groundwaters of this sub-area do not form a problem related to RSC.
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| 6. |
- Goncalves, Leticia C. P., et al.
(författare)
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Boosting photobioredox catalysis by morpholine electron donors under aerobic conditions
- 2019
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Ingår i: Catalysis Science & Technology. - : Royal Society of Chemistry. - 2044-4753 .- 2044-4761. ; 9:10, s. 2682-2688
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Tidskriftsartikel (refereegranskat)abstract
- Light-driven reduction of flavins, e.g. FAD or FMN, by sacrificial electron donors emerged as a convenient method to promote biocatalytic transformations. However, flavin activation has been restricted to oxygen-free conditions to prevent enzyme deactivation caused by reactive oxygen species (ROS). Herein, we show that the photoreduction of FMN by morpholines, including 3-(N-morpholino)propanesulfonic acid (MOPS), lessens the deactivation of the enoate reductase XenB from Pseudomonas sp. during the stereoselective asymmetric enzymatic reduction of a model ,-unsaturated diketone under aerobic conditions, leading to a 91% GC-yield and a stereoselectivity greater than 94%. The kinetic stability of the thermolabile XenB was increased by more than 20-fold in MOPS buffer compared to that in Tris-HCl buffer, and a pronounced positive effect on the transition midpoint temperature was observed. The reactive form of the FMN photocatalyst is stabilized by the formation of a (3)[FMN--MOPS+] ensemble, which reduces the formation of hydrogen peroxide and other ROS in the presence of oxygen. These results contribute to broaden the application of photobiocatalytic transformations using flavin-dependent reductases.
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| 7. |
- Goncalves, Leticia C. P., et al.
(författare)
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Morpholine-based buffers activate aerobic photobiocatalysis via spin correlated ion pair formation
- 2019
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Ingår i: Catalysis Science & Technology. - : ROYAL SOC CHEMISTRY. - 2044-4753 .- 2044-4761. ; 9:6, s. 1365-1371
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Tidskriftsartikel (refereegranskat)abstract
- The use of enzymes for synthetic applications is a powerful and environmentally-benign approach to increase molecular complexity. Oxidoreductases selectively introduce oxygen and hydrogen atoms into myriad substrates, catalyzing the synthesis of chemical and pharmaceutical building blocks for chemical production. However, broader application of this class of enzymes is limited by the requirements of expensive cofactors and low operational stability. Herein, we show that morpholine-based buffers, especially 3-(N-morpholino)propanesulfonic acid (MOPS), promote photoinduced flavoenzyme-catalyzed asymmetric redox transformations by regenerating the flavin cofactor via sacrificial electron donation and by increasing the operational stability of flavin-dependent oxidoreductases. The stabilization of the active forms of flavin by MOPS via formation of the spin correlated ion pair (3)[flavin(-)-MOPS+] ensemble reduces the formation of hydrogen peroxide, circumventing the oxygen dilemma under aerobic conditions detrimental to fragile enzymes.
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| 8. |
- Hertzberg, Joachim, et al.
(författare)
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The RACE Project : Robustness by Autonomous Competence Enhancement
- 2014
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Ingår i: Künstliche Intelligenz. - : Springer Berlin/Heidelberg. - 0933-1875 .- 1610-1987. ; 28:4, s. 297-304
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports on the aims, the approach, and the results of the European project RACE. The project aim was to enhance the behavior of an autonomous robot by having the robot learn from conceptualized experiences of previous performance, based on initial models of the domain and its own actions in it. This paper introduces the general system architecture; it then sketches some results in detail regarding hybrid reasoning and planning used in RACE, and instances of learning from the experiences of real robot task execution. Enhancement of robot competence is operationalized in terms of performance quality and description length of the robot instructions, and such enhancement is shown to result from the RACE system.
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