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| 2. |
- Vivekanand, Aashlesha Chekkala, et al.
(författare)
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Microplastics in aquatic environment : Challenges and perspectives
- 2021
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Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 282
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Tidskriftsartikel (refereegranskat)abstract
- The occurrence of microplastics in the aquatic environment has become a growing concern globally. Microplastics pose a hazard to the ecological system, and their presence, particularly in the water, has an adverse impact on human health and the ecosystem. Microplastics are released into the environment directly from everyday used plastic items, degradation of plastics, industries, and wastewater treatment plants. Once these contaminants enter the water, aquatic life feeds on them, and microplastics enter the food chain and cause severe health hazards. An assessment of microplastics' ecological risks is essential; however, it is challenging in the present scenario due to limited information available. To fill these knowledge gaps, this paper comprehensively reviews the sources and transport of microplastics in the water environment and their environmental and health effects, global policy frameworks, analytical techniques for microplastic detection, and control strategies to prevent microplastics release in the aquatic environment.
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| 3. |
- Ayele, Getnet Tadesse, et al.
(författare)
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An extended energy hub approach for load flow analysis of highly coupled district energy networks: Illustration with electricity and heating
- 2018
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 212, s. 850-867
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Tidskriftsartikel (refereegranskat)abstract
- Energy systems at district/urban level are getting more complex and diversified from time to time. Different energy carriers are coupled each other to meet various types of energy demands. The conventional way of analyzing energy networks independently does not reflect the true nature of the coupled networks. One of such a promising coupled multi-carrier energy system (MCES) is the combination of district heating and electricity networks. The coupling between these two networks is increasing due to the integration of co– and poly-generation technologies at the distribution networks. Recent literatures tried to address a load flow analysis for lightly coupled networks by formulating case-specific load flow models. This paper presents a more general and flexible tool developed using Matlab® which can be used to conduct the load flow analysis of highly coupled electricity and heating networks. An energy hub concept is extended further to formulate a general model in which local generations and detailed network parameters of MCES can be taken into account. Coupled heating and electricity networks are modeled in detail for illustration. The flexibility and generality of the model are then tested by considering case studies with different network topologies (tree and meshed). A comparison is also made with a model used in recent literature. The results show that the proposed model is more accurate. The main contribution of this paper can be summarized by the following five points: (1) Coupling matrices are used to relate network power flow equations of different energy carriers; (2) Hybrid hydraulic head and pipe flow equations are used to develop the hydraulic model which can be applied for both types of tree and meshed heating networks with the possibility of pumping units; (3) A general thermal model that relates steady state temperature drops and mass flow rates, even during change of flow direction, is developed for the heating network; (4) The electricity network is modeled with the possibility of tap changing transformers; (5) The overall system of equations are solved as a single problem using Newton-Raphson iterative method.
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| 5. |
- Pino Rodríguez, Aymé, 1961-
(författare)
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El uso de combinaciones de palabras con que en un corpus de aprendices suecos de español como lengua extranjera
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Previous research in phraseological studies has approached the difficulties that learners of foreign and second languages have to produce word combinations derived from idiomatic- or phraseological principles. Using the theoretical framework of Sinclair’s idiom principle and applying a corpus-based methodological approach to contrastive linguistics and the study of interlanguage, I have analyzed the use of Spanish word sequences by Swedish learners. I argue that Swedish learners of Spanish as a Foreign Language overuse different word combinations due to mother tongue influence (Swedish), and as a consequence of different accommodation strategies in their interlanguage. The differences in function and frequency of use of these combinations decrease proportionally with the development of learners’ knowledge and skills in the target language. The thesis presents a quantitative and qualitative analysis of word combinations with que: lo que, de que, algo que, dice que in 135 texts (corpus SAELE-Swedish students of Spanish as a foreign language) produced by 45 Swedish learners of Spanish as a Foreign Language (27 women and 18 men), at two Swedish universities. The sample represents 25.4% (P<0.005) of the total of 177 students (universe) enrolled in academic courses in Spanish as a Foreign Language. The study is contrastive corpus analysis of argumentative texts written by intermediate-level Swedish learners of Spanish (Corpus SAELE compiled by the author) which was compared with two control groups: one of native speakers of Spanish (control corpus of Spanish CEDEL2) and another of native speakers of Swedish (control corpus of Swedish ARGUS). The main research question was to examine whether Swedish learners of Spanish as a Foreign Language tend to use different word combinations with que: (lo que, de que, algo que, dice que) than Spanish and Swedish-natives. In addition, I have aimed at: (a) to carry out a survey based on sociolinguistic data obtained from students and (b) to investigate if the level of proficiency of Swedish learners of Spanish Foreign Language corresponded to A2-B1 within Common European Framework of Reference for Languages. Due to its polysemous nature, que has a high frequency of use in the Spanish control corpora (3.45%). The Swedish equivalents att appeared with a frequency of 3.75% and som with of 2.13% in the Swedish control corpus. In the corpus SAELE que appeared with a frequency of 2.95%. The study has shown the differences in use and frequency in the production of Swedish learners with Spanish and Swedish speakers. The combination dice que seems to be the most frequently used by Swedish learners of Spanish as a foreign language, although it was 21.6 % more frequent among the Swedish learners than Spanish-speakers (control corpus CEDEL2) and 13.44 % than among Swedish-speakers (control corpus ARGUS). The overuse of the combination dice que could reflect a tendency by Swedish learners of Spanish to use formulations typical of speech rather than of writing. In addition it was found that Swedish learners of Spanish use the combination algo que (0.4%) double as often as Spanish-speakers and lo que equivalent to det som 6.57% and to vad som 7.47 % more frequently than Swedish-speakers. It shows learners linguistics continuum if you consider that lo que is the combination most frequently used by Spanish-speakers and the Swedish equivalents to algo que were the combinations most commonly used by Swedish-speakers. The analyses of the essays by the Swedish learners of Spanish as a Foreign Language participating in the present study showed that their skills conformed to level A2 to B1 (Common European Framework of Reference for Languages) according to the analyses of their essays. The learners produced some word combinations similar to those produced by Spanish natives, but made some errors in their written production. It was found that individual differences among participants with regard to age, length of study of Spanish in Sweden or a Spanish-speaking country could be another factor to take in account. A comparison of the Swedish learners with more advanced students of Spanish (level B1-B2), indicated that the latter used particle in a way that is directly proportional to the preferred choice by a native speaker. Pedagogical conclusions will be used to develop concordance and collocation-based exercises as a way of raising students’ awareness of the use and function of recurrent words combinations with que in their written production.
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| 6. |
- Moscoso del Prado Martin, Fermin, et al.
(författare)
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An integration of vector-based semantic analysis and simple recurrent networks for the automatic acquisition of lexical representations from unlabeled corpora
- 2002. - 1
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Konferensbidrag (refereegranskat)abstract
- This study presents an integration of Simple Recurrent Networks to extract grammatical knowledge and Vector-Based Semantic Analysis to acquire semantic information from large corpora. Starting from a large, untagged sample of English text, we use Simple Recurrent Networks to extract morpho-syntactic vectors in an unsupervised way. These vectors are then used in place of random vectors to perform Vector-Based Semantic Analysis. In this way, we obtain rich lexical representations in the form of high-dimensional vectors that integrate morpho-syntactic and semantic information about words. Apart from incorporating data from the different levels, we argue how these vectors can be used to account for the particularities of each different word token of a given word type. The amount of lexical knowledge acquired by the technique is evaluated both by statistical analyses comparing the information contained in the vectors with existing `hand-crafted' lexical resources such as CELEX and WordNet, and by performance in language proficiency tests. We conclude by outlining the cognitive implications of this model and its potential use in the bootstrapping of lexical resources.
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| 7. |
- Kian, L. K., et al.
(författare)
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Isolation and characterization of nanocrystalline cellulose from roselle-derived microcrystalline cellulose
- 2018
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Ingår i: International Journal of Biological Macromolecules. - : Elsevier B.V.. - 0141-8130 .- 1879-0003. ; 114, s. 54-63
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Tidskriftsartikel (refereegranskat)abstract
- Roselle fiber is a renewable and sustainable agricultural waste enriched with cellulose polysaccharides. The isolation of Nanocrystalline cellulose (NCC) from roselle-derived microcrystalline cellulose (MCC) is an alternative approach to recover the agricultural roselle plant residue. In the present study, acid hydrolysis with different reaction time was carried out to degrade the roselle-derived MCC to form NCC. The characterizations of isolated NCC were conducted through Fourier Transform Infrared Ray (FTIR), Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS), Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). As evaluated from the performed morphological investigations, the needle-like shape NCC nanostructures were observed under TEM and AFM microscopy studies, while irregular rod-like shape of NCC was observed under FESEM analysis. With 60 min hydrolysis time, XRD analysis demonstrated the highest NCC crystallinity degree with 79.5%. In thermal analysis by TGA and DSC, the shorter hydrolysis time tended to produce NCC with higher thermal stability. Thus, the isolated NCC from roselle-derived MCC has high potential to be used in application of pharmaceutical and biomedical fields for nanocomposite fabrication.
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| 8. |
- Peterson, Kristoffer, et al.
(författare)
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Systematic Tuning of Fluoro-galectin-3 Interactions Provides Thiodigalactoside Derivatives with Single-Digit nM Affinity and High Selectivity
- 2018
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Ingår i: Journal of Medicinal Chemistry. - : American Chemical Society (ACS). - 0022-2623 .- 1520-4804. ; 61:3, s. 1164-1175
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Tidskriftsartikel (refereegranskat)abstract
- Symmetrical and asymmetrical fluorinated phenyltriazolyl-thiodigalactoside derivatives have been synthesized and evaluated as inhibitors of galectin-1 and galectin-3. Systematic tuning of the phenyltriazolyl-thiodigalactosides' fluoro-interactions with galectin-3 led to the discovery of inhibitors with exceptional affinities (Kd down to 1-2 nM) in symmetrically substituted thiodigalactosides as well as unsurpassed combination of high affinity (Kd 7.5 nM) and selectivity (46-fold) over galectin-1 for asymmetrical thiodigalactosides by carrying one trifluorphenyltriazole and one coumaryl moiety. Studies of the inhibitor-galectin complexes with isothermal titration calorimetry and X-ray crystallography revealed the importance of fluoro-amide interaction for affinity and for selectivity. Finally, the high affinity of the discovered inhibitors required two competitive titration assay tools to be developed: a new high affinity fluorescent probe for competitive fluorescent polarization and a competitive ligand optimal for analyzing high affinity galectin-3 inhibitors with competitive isothermal titration calorimetry.
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| 9. |
- Viveka, Shivapura, et al.
(författare)
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Synthesis, characterization, single crystal X-ray diffraction and DFT studies of ethyl 5-methyl-1-phenyl-1H-pyrazole-4-carboxylate
- 2016
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Ingår i: Molecular Crystals and Liquid Crystals. - : Informa UK Limited. - 1542-1406 .- 1563-5287. ; , s. 135-145
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Tidskriftsartikel (refereegranskat)abstract
- The present study describes the synthesis, spectroscopic, and single crystal X-ray structural analysis of ethyl 5-methyl-1-phenyl-1H-pyrazole-4-carboxylate. The pyrazole ester of formula [C13H14N2O2] was prepared from the three-component one-pot condensation reaction of ethyl acetoacetate, N,N-dimethyldimethoxymethanamine, and phenyl hydrazine. The product was crystallized by using ethanol as solvent. The structure of the compound was confirmed by elemental analysis, Fourier transforms infrared (IR), thermogravimetric analysis, UV-visible (UV-Vis), 1H NMR, and single-crystal X-ray diffraction studies. The gas-phase molecular geometry and the electronic structure-property of the molecule were calculated at the density functional theory. The frontier molecular orbitals, theoretical UV-Vis, and IR stretching vibrations were also reported. The compound crystallizes in the monoclinic system with the space group P21/c and Z = 4. The unit cell parameters are a = 12.141(3) Å, b = 13.934(4) Å, c = 7.2777(18) Å, and β = 97.816(14)0. The structure is stabilized by an intermolecular interaction of type C-H···O and the structure also involves C-H···π interactions
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