| 1. |
- Danish, Muhammad, et al.
(författare)
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Effect of solution matrix and pH in Z-nZVI-catalyzed percarbonate system on the generation of reactive oxygen species and degradation of 1,1,1-trichloroethane
- 2017
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Ingår i: Water Science and Technology. - London, UK : IWA PUBLISHING. - 1606-9749 .- 1607-0798. ; 17:6, s. 1568-1578
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Tidskriftsartikel (refereegranskat)abstract
- This study primarily focuses on evaluating the effects of solution matrix and pH for the generation of reactive oxygen species (ROSs) in a Z-nZVI-catalyzed sodium percarbonate (SPC) system to degrade 1,1,1-trichloroethane (1,1,1-TCA) in the absence and presence of a reducing agent (RA), i.e. hydroxylamine. Degradation of 1,1,1-TCA was 49.5% and 95% in the absence and presence of RA. Probe tests confirmed the generation of major hydroxyl radicals (OH center dot) and minor superoxide species (O-2(-center dot)), and scavenger tests verified the key role of OH center dot and less of O-2(-center dot) radicals. Degradation of 1,1,1-TCA decreased significantly in the presence of Cl- and HCO3-, while NO3- and SO42- had negligible effects in the absence of RA. Addition of RA significantly enhanced 1,1,1-TCA degradation by generating more OH center dot and O-2(-center dot) radicals in the presence of anions. Degradation of 1,1,1-TCA increased in the acidic range (1-5), while an inhibitive trend from neutral to basic (7-9) was observed. In contrast, a significant increase in 1,1,1-TCA degradation was observed with the addition of RA at all pH values (1-9). In conclusion, the anions and pH significantly influenced the generation and intensity of ROSs and 1,1,1-TCA was effectively degraded in the Z-nZVI-catalyzed SPC system in the presence of RA.
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| 2. |
- Danish, Muhammad, et al.
(författare)
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Efficient transformation of trichloroethylene activated through sodium percarbonate using heterogeneous zeolite supported nano zero valent iron-copper bimetallic composite
- 2017
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Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 308, s. 396-407
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Tidskriftsartikel (refereegranskat)abstract
- Zeolite supported nano zero valent iron copper bimetallic composite (Z-nZVFe-Cu) was synthesized using an ion exchange method. The morphology and physico-chemical properties of the Z-nZVFe-Cu composite were determined using transmission electron microscopy (TEM), scanning electron microscopy (SEM), Brunauer Emmett Teller (BET), energy dispersive X-ray spectra (EDS), Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometer (XRD). The results showed that iron and copper nano particles were well dispersed on the zeolite sheet. The degradation efficiency of trichloroethylene (TCE) achieved was more than 95% using Z-nZVFe-Cu as a heterogeneous Fenton like catalyst. An efficient removal of total organic carbon (TOC) was promoted as compared to zeolite supported iron nano composite (Z-nZVFe) and unsupported nano iron (nZVFe). Electron spin resonance (ESR) detection confirmed the intensity of hydroxyl radicals (OH.) in the system. While benzoic acid (BA), a probe indicator for the quantification of OH., demonstrated the higher intensity of hydroxyl radicals in Z-nZVFe-Cu as compared to Z-nZVFe and nZVFe. The less iron and copper leaching of from Z-nZVFe-Cu presented its higher stability and better catalytic activity, displaying its potential long term applications for TCE degradation in groundwater. (C) 2016 Elsevier B.V. All rights reserved.
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| 3. |
- Danish, Muhammad, et al.
(författare)
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Role of reactive oxygen species and effect of solution matrix in trichloroethylene degradation from aqueous solution by zeolite-supported nano iron as percarbonate activator
- 2016
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Ingår i: Research on chemical intermediates (Print). - : Springer. - 0922-6168 .- 1568-5675. ; 42:9, s. 6959-6973
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Tidskriftsartikel (refereegranskat)abstract
- The role of reactive oxygen species (ROSs) and effect of solution matrix have been investigated for the degradation of trichloroethylene (TCE). Zeolite-supported nano iron (Z-nZVI) was synthesized as an activator to catalyze sodium percarbonate (SPC) with or without hydroxylamine, i.e. as reducing agent (RA). The probe tests confirmed the generation of OH center dot and O-2(-center dot) in the Z-nZVI activated SPC system in absence of the RA, while the presence of RA significantly increased the generation of OH center dot and O-2(-center dot) radicals. Scavenger tests demonstrated that OH center dot was the main ROS responsible for TCE degradation, whereas O-2(-center dot) also participated in TCE degradation. From the solution matrix perspective, the experimental results confirmed significant scavenging effects of Cl- (1.0, 10.0, and 100 mmol L-1) and HCO3- (1.0 and 10.0 mmol L-1), whereas the scavenging effects were fairly impeded at 100 mmol L-1 concentration of HCO3-. On the other hand, a considerable decline in scavenging effect was observed in the presence of RA in tested Cl and HCO3- concentration ranges. In addition, negligible scavenging effects of NO3- and SO42- anions were found in all tested concentrations. The effect of initial solution pH on catalytic activity indicated a significant increase in the TCE degradation in the presence of RA even at higher pH value of 9. The results indicated that the Z-nZVI activated SPC system in presence of RA can effectively degrade chlorinated organic solvents, but it is important to consider the intensive existence of anions in groundwater.
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| 4. |
- Eriksson, Hanna M., 1978-, et al.
(författare)
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High-yield expression and purification of a monotopic membrane glycosyltransferase
- 2009
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Ingår i: Protein Expression and Purification. - : Elsevier. - 1046-5928 .- 1096-0279. ; 66:2, s. 143-148
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Tidskriftsartikel (refereegranskat)abstract
- Membrane proteins are essential to many cellular processes. However, the systematic study of membrane protein structure has been hindered by the difficulty in obtaining large quantities of these proteins. Protein overexpression using Escherichia coli is commonly used to produce large quantities of protein, but usually yields very little membrane protein. Furthermore, optimization of the expressing conditions, as well as the choice of detergent and other buffer components, is thought to be crucial for increasing the yield of stable and homogeneous protein. Herein we report high-yield expression and purification of a membrane-associated monotopic protein, the glycosyltransferase monoglucosyldiacylglycerol synthase (alMGS), in E. coli. Systematic optimization of protein expression was achieved through controlling a few basic expression parameters, including temperature and growth media, and the purifications were monitored using a fast and efficient size-exclusion chromatography (SEC) screening method. The latter method was shown to be a powerful tool for fast screening and for finding the optimal protein-stabilizing conditions. For alMGS it was found that the concentration of detergent was just as important as the type of detergent, and a low concentration of n-Dodecyl-β-D-maltoside (DDM) (~1× critical micelle concentration) was the best for keeping the protein stable and homogeneous. By using these simply methods to optimize the conditions for alMGS expression and purification, the final expression level increase by two orders of magnitude, reaching 170 mg of pure protein per litre culture.
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| 5. |
- Farooq, Usman, et al.
(författare)
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Synthesis of nZVI@reduced graphene oxide : an efficient catalyst for degradation of 1,1,1-trichloroethane (TCA) in percarbonate system
- 2017
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Ingår i: Research on chemical intermediates (Print). - : SPRINGER. - 0922-6168 .- 1568-5675. ; 43:5, s. 3219-3236
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Tidskriftsartikel (refereegranskat)abstract
- Graphene-oxide-supported nano zero-valent iron (nZVI) composite (nZVI-rGO) was synthesized and tested as an efficient percarbonate activator for degradation of 1,1,1-trichloroethane (TCA). Significant dispersion of nZVI on the surface of reduced graphene oxide (rGO) was observed, with good limitation of nanoparticle agglomeration and aggregation. Good TCA degradation efficiency of 90% was achieved in 2.5 h in presence of 0.8 g/l nZVI-rGO catalyst and 30 mM sodium percarbonate (SPC) oxidant; however, excessive catalyst or oxidant concentration reduced the degradation efficiency. Investigation of reactive oxygen species using radical probe compounds as well as radical scavengers confirmed presence of hydroxyl (OH center dot) and superoxide () radicals that are responsible for the TCA degradation. The morphology and surface characteristics of the heterogeneous catalyst were analyzed by transmission electron microscopy and scanning electron microscopy. Brunauer-Emmett-Teller analysis revealed that the synthesized catalyst had large surface area and small particle size of 299.12 m(2)/g and 20.10 nm, respectively, compared with 5.33 m(2)/g and 1.12 A mu m for bare graphene oxide. X-ray diffraction analysis revealed good dispersion of nZVI on the surface of rGO. Fourier-transform infrared characteristic peaks confirmed strong attachment of Fe onto the rGO surface. Energy-dispersive spectroscopy analysis validated the stoichiometric composition of the prepared Fe/rGO material. In conclusion, use of nZVI-rGO-activated SPC could represent an alternative technique for remediation of TCA-contaminated groundwater.
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| 6. |
- Guo, Xiaoyi, et al.
(författare)
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Random Fourier features-based sparse representation classifier for identifying DNA-binding proteins
- 2022
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Ingår i: Computers in Biology and Medicine. - London : Elsevier. - 0010-4825 .- 1879-0534. ; 151
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Tidskriftsartikel (refereegranskat)abstract
- DNA-binding proteins (DBPs) protect DNA from nuclease hydrolysis, inhibit the action of RNA polymerase,prevents replication and transcription from occurring simultaneously on a piece of DNA. Most of theconventional methods for detecting DBPs are biochemical methods, but the time cost is high. In recent years,a variety of machine learning-based methods that have been used on a large scale for large-scale screeningof DBPs. To improve the prediction performance of DBPs, we propose a random Fourier features-based sparserepresentation classifier (RFF-SRC), which randomly map the features into a high-dimensional space to solvenonlinear classification problems. And ?2,1-matrix norm is introduced to get sparse solution of model. Toevaluate performance, our model is tested on several benchmark data sets of DBPs and 8 UCI data sets. RFF-SRCachieves better performance in experimental results. © 2022 Elsevier Ltd.
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| 7. |
- Qiu, Huibin, et al.
(författare)
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Steric and temperature control of enantiopurity of chiral mesoporous silica
- 2008
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 112:6, s. 1871-1877
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Tidskriftsartikel (refereegranskat)abstract
- To elucidate the factors and mechanisms that control the chiral mesoporous silica (CMS) formation, we employed a series of chiral amphiphilic molecules derived from nine different amino acids as templates and quantitatively investigated the effects of the substituent attached to the chiral center of amino acid upon CMS synthesis at various temperatures. The enantiomeric excess (ee) of the CMS obtained was a critical function of both the substituent’s steric bulk and the temperature, and eventually exceeded 90% ee by performing the CMS synthesis at 288 K in the presence of amphiphilic N-palmitoyl-Phe or Met. The temperature dependence study of the product’s ee not only gave the high ee’s but also enabled us to determine the differential enthalpy (Delta Delta H) and entropy (Delta Delta S) changes for antipodal CMS formation, which simultaneously increased with increasing steric bulk of the amino acid’s substituent, indicating their critical roles in determining the CMS’s enantiopurity. The present results also indicate that the CMS synthesis is a convenient tool for taking a snapshot of an average image of the dynamically fluctuating supramolecular aggregates with quantitative information (ee).
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| 8. |
- Sodergren, Erica, et al.
(författare)
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The genome of the sea urchin Strongylocentrotus purpuratus.
- 2006
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 314:5801, s. 941-52
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Tidskriftsartikel (refereegranskat)abstract
- We report the sequence and analysis of the 814-megabase genome of the sea urchin Strongylocentrotus purpuratus, a model for developmental and systems biology. The sequencing strategy combined whole-genome shotgun and bacterial artificial chromosome (BAC) sequences. This use of BAC clones, aided by a pooling strategy, overcame difficulties associated with high heterozygosity of the genome. The genome encodes about 23,300 genes, including many previously thought to be vertebrate innovations or known only outside the deuterostomes. This echinoderm genome provides an evolutionary outgroup for the chordates and yields insights into the evolution of deuterostomes.
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| 9. |
- Tollstoy Tegler, Lotta, et al.
(författare)
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Cell-free expression, purification, and ligand-binding analysis of Drosophila melanogaster olfactory receptors DmOR67a, DmOR85b and DmORCO
- 2015
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Ingår i: Scientific Reports. - : Nature Publishing Group: Open Access Journals - Option C / Nature Publishing Group. - 2045-2322. ; 5:7867
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Tidskriftsartikel (refereegranskat)abstract
- Insects transmit numerous devastating diseases, including malaria, dengue fever, and sleeping sickness. Olfactory cues guide insects to their hosts, and are thus responsible for disease transmission. Understanding the molecular basis of insect olfaction could facilitate the development of interventions. The first step is to heterologously overexpress and purify insect olfactory receptors (ORs). This is challenging, as ORs are membrane proteins. Here, we show that insect ORs and their co-receptor can be expressed in an E. coli cell-free system. After immunoaffinity chromatography, the ORs are similar to 95% pure, and up to 1 mg/10 ml reaction is obtained. Circular dichroism together with microscale thermophoresis indicate that each receptor is properly folded, and can bind its respective ligand. This is the first time insect ORs have been expressed in an E. coli system. The methods described here could facilitate future structure-function studies, which may aid in developments to alleviate the suffering of millions caused by insect-transmitted diseases.
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| 10. |
- Tollstoy Tegler, Lotta, et al.
(författare)
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The G protein coupled receptor CXCR4 designed by the QTY code becomes more hydrophilic and retains cell signaling activity
- 2020
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Ingår i: Scientific Reports. - : NATURE RESEARCH. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- G protein-coupled receptors (GPCRs) are vital for diverse biological functions, including vision, smell, and aging. They are involved in a wide range of diseases, and are among the most important targets of medicinal drugs. Tools that facilitate GPCR studies or GPCR-based technologies or therapies are thus critical to develop. Here we report using our QTY (glutamine, threonine, tyrosine) code to systematically replace 29 membrane-facing leucine, isoleucine, valine, and phenylalanine residues in the transmembrane alpha-helices of the GPCR CXCR4. This variant, CXCR4(QTY29), became more hydrophilic, while retaining the ability to bind its ligand CXCL12. When transfected into HEK293 cells, it inserted into the cell membrane, and initiated cellular signaling. This QTY code has the potential to improve GPCR and membrane protein studies by making it possible to design functional hydrophilic receptors. This tool can be applied to diverse alpha-helical membrane proteins, and may aid in the development of other applications, including clinical therapies.
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