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1.
Behruz Shaker Shiran Arne Skauge 《Journal of Dispersion Science and Technology》2014,35(12):1656-1664
Linked polymer solution (LPS) is nano-size particles made of hydrolyzed polyacrylamide (HPAM) cross-linked with aluminum citrate. The propagation of LPS has been compared to non-cross-linked polymers at low brine salinity condition. The possible differences in properties and potentials for oil recovery have been investigated using water-wet and intermediate-wet cores. The target oil for polymer flooding (PF) is assumed to be the portion of the reservoir that has been bypassed by water during waterflooding and not the residual oil saturation in flooded zones. Our recent studies have shown that a positive synergy can be obtained by combining low salinity and PF. It has been claimed in the literature that cross-linking polymer such as colloidal dispersion gels (colloidal dispersion gels (CDG), micron-size aggregates) or LPS (nano-size particles) would extend the application of polymers to also include change in residual oil saturation. The results of this study indicated higher pressure buildup when low salinity LPS was propagated through brine saturated cores compared to low salinity polymer solution. The pressure buildup was even stronger for high salinity LPS injection. In two phase flow experiments, both polymer and LPS under low salinity condition, showed approximately similar propagation and oil recovery potential when injected into water-wet and intermediate-wet cores. 相似文献
2.
Infrared spectroscopy studies of cation effects on lipopolysaccharides in aqueous solution 总被引:1,自引:0,他引:1
The conformation of amphiphilic lipopolysaccharides (LPS) influences the behavior of free and cell-bound LPS in aqueous environments, including their adhesion to surfaces. Conformational changes in Pseudomonas aeruginosa serotype 10 LPS aggregates resulting from changes in solution pH (3, 6, and 9), ionic strength [I] 1, 10, and 100 mmol L−1, and electrolyte composition (NaCl and CaCl2) were investigated via attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy. ATR-FTIR data indicate that LPS forms more stable aggregates in NaCl relative to CaCl2 solutions. Time- and cation-dependent changes in ATR-FTIR data suggest that LPS aggregates are perturbed by Ca2+ complexation at lipid A phosphoryl groups, which leads to reorientation of the lipid A at the surface of a ZnSe ATR internal reflection element (IRE). Polarized ATR-FTIR investigations reveal orientation of LPS dipoles approximately perpendicular to the IRE plane for both Na- and Ca-LPS. The results indicate that changes in solution chemistry strongly impact the conformation, intermolecular and interfacial behavior of LPS in aqueous systems. 相似文献
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An immunoglobulin-rich fraction has been prepared from ovine blood in our laboratory. We have investigated its antibacterial
activity and binding activity to pathogenic whole cell antigens, lipopolysaccharide (LPS) and staphylococcal enterotoxin B.
Ovine immunoglobulin concentrate (OIC) comprised about 73 ± 2% of IgG and 11 ± 1% of IgM on a protein basis. It inhibited
the growth of all 13 strains of pathogens tested, but the inhibitory activity varied according to bacterial strain. The inhibitory
activity of OIC was attributed to the high contents of undenatured immunoglobulin present because its inhibitory activity
was destroyed by pepsin digestion and heat treatment (65°C for 30 min). OIC bound to all the Gram-positive and Gram-negative
pathogens, regardless of cell wall structure. The highest magnitude of crossreactivity to whole cell antigens was against
Staphylococcus epidermidis and Shigella soneii strains (p < 0.001). The binding activity of OIC to LPS obtained from Escherichia coli O111:B4 and Salmonella enterica serotype typhimurium was assessed by enzyme-linked immunosorbent assay and lymphoblast K-562 proliferation assay. OIC bound to LPS with a binding
activity that was dependent on OIC concentration and saturable, showing typical hyperbolic curves. For toxin-binding activity,
an OIC concentration-dependent trend like that for LPS-binding activity was also observed. This preliminary evidence suggests
that the OIC used in this study could be a promising supplement for protecting against pathogenic bacteria. 相似文献
5.
Giuseppe Antonio Malfa Marinella De Leo Rosa Tundis Alessandra Braca Monica Rosa Loizzo Claudia Di Giacomo Francesco Maria Raimondo Anahi Elena Ada Bucchini Rosaria Acquaviva 《Molecules (Basel, Switzerland)》2022,27(23)
Brassica villosa subsp. drepanensis (Caruel) Raimondo & Mazzola, belonging to the Brassica oleracea complex, is a wild edible plant endemic to western Sicily and a relative of modern cultivated Brassica crops. In this study, the antioxidant properties, anti-inflammatory activities, enzymatic inhibition, and cytotoxicity in cancer cells of B. villosa subsp. drepanensis leaf ethanolic extract were analysed for the first time. In addition, its chemical profile was investigated partitioning the total 70% ethanol extract among ethyl acetate, n-butanol, and water to obtain three residues that were subjected to chromatographic separation. Two flavonol glycosides, a phenol glucoside, two amino acids, and purine/pyrimidine bases were obtained. The presence of the glucosinolate glucoiberin was detected in the water extract by UHPLC-MS analysis. The total polyphenol and flavonoid content of the 70% ethanol extract showed good antioxidant capacities and anti-inflammatory properties by reducing nitric oxide release and reactive oxygen species levels and increasing glutathione in lipopolysaccharide-stimulated RAW 264.7 cells. The extract inhibited the enzymatic activity of α-amylase, α-glucosidase, and, significantly, of lipase. The MTT assay showed that the extract did not affect the viability of normal HFF-1 and RAW 264.7 cells. Among the cancer cell lines tested, an antiproliferative action was only observed in CaCo-2. The cytotoxicity of the extract was further confirmed by LDH release assay and by the destabilization of the oxidative balance. Results confirmed the antioxidant properties of the crude extract responsible for the anti-inflammatory effect on healthy cells and cytotoxicity in cancer cells. 相似文献
6.
The LPS concept, a new way to look at anionic conductors 总被引:1,自引:0,他引:1
A new approach to anionic conduction is presented, and illustrated using already well-known anion conductors, as well as the recently discovered fast oxide-ion conductor La2Mo2O9. The so-called LPS (lone-pair substitution) concept could be used to seek for novel families of anion conductors, issued from already known compounds with lone-pair elements. It is based on the similarity in volume between an electronic lone pair and oxide or fluoride anions, and on the vacancy created by the replacement of a lone-pair by a non-lone-pair cation. A tentative list of the most appropriate substituting elements for given lone-pair cations is presented. 相似文献
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Sepideh Fereshteh Hourieh Kalhor Amin Sepehr Hamzeh Rahimi Mahdi Zafari Reza Ahangari Cohan Farzad Badmasti 《印度化学会志》2022,99(2):100319
BackgroundAcinetobacter baumannii is a highly antimicrobial resistant nosocomial pathogen. Resistance to currently used antibiotics has limited effective drugs against this bacterium. This study aimed to propose a rational inhibitor design against the LpxA protein of A. baumannii using a virtual screening method based on a similar structure of ligands.MethodsIn this study, we targeted LpxA protein, which is involved in the early stage of LPS biosynthesis. In the next step, we used Peptide920 and 1,2- Ethanediol as templates to find similar compounds using Drugbank and Zinc15 webservers, respectively. Subsequently, molecular dynamics (MD) simulations were carried out for LpxA protein and two complexes of ZINC895081 and Macrolactam-1 which represented the highest binding affinity and best conformation. Finally, ADMET properties, water solubility and drug-likeness of the desired compounds were evaluated using SwissADME and DruLiTo softwares.ResultsAccording to considered criteria, Drugbank suggested 5 compunds including Ilomastat, Macrolactam-1, Macrolactam-2, Macimorelin, and Oglufanide. On the other hand, Zinc15 webserver suggested 4 compunds including ZINC895048, ZINC895081, ZINC901061 and ZINC1531008. The result of the HDOCK server and Molegro virtual docker (MVD) showed that Macrolactam-1 and ZINC895081 (Citrate) had the highest docking score. In addition, MD simulations showed that ZINC895081 and Macrolactam-1 ligands have the stable binding to the LpxA protein. According to Lipinski's rule, these two compounds are non-carcinogenic, non-toxic and promising inhibitors against LpxA of A. baumannii.ConclusionIt seems that Macrolactam-1 and ZINC895081 (Citrate) are two valuable promising inhibitors against the LpxA protein of A. baumannii. Further in vitro and in vivo experiments are needed to confirm the capabilities of these proposed compounds against A. baumannii. 相似文献
8.
Fan-lin Wu Yong-hao Hu Peng Ji Chen-chen Li Jian He 《Biomedical chromatography : BMC》2022,36(6):e5362
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Ann Louise Worsøe Jørgensen Helle Risdahl Juul‐Madsen Jan Stagsted 《Journal of mass spectrometry : JMS》2009,44(3):338-345
A simple and sensitive ligand affinity capture method (LAC) was developed to detect biotinylated biomolecules bound to a biotin–avidin base by matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry (MALDI ToF MS). Glass slides covered with a metal film for MALDI MS applications were treated with amino‐silane and derivatized with biotin followed by binding of avidin. Washing buffers with high ionic strength increased the specificity of the subsequent binding of biotinylated biomolecules to the avidin layer. A combined thin layer‐dried droplet method using α‐cyano‐4‐hydroxycinnamic acid (CHCA) in acetone or ethyl acetate resulted in the most intense ions of biotinylated polymyxin B, whereas the matrix conditions did not influence the detection of angiotensin II. Addition of biotinylated biomolecules in the low femtomole to low picomole range resulted in sufficient ion intensity for detection by the LAC method. The LAC concept was extended by binding of biotinylated lipopolysaccharide to the biotin–avidin base followed by preferential capture and specific detection of the binding antagonist polymyxin B. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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A new stage of endotoxin research was brought about by structure elucidation and chemical synthesis of lipid A, the lipophilic partial structure of the lipopolysaccharide (LPS) of Gram-negative bacteria. Synthetic lipid A exhibited full endotoxic activity, which gave unequivocal evidence for the concept that lipid A is the active entity of endotoxin. Various lipid A analogues, as well as their radiolabeled derivatives and more complex partial structures of LPS, were also synthesized. By the use of these synthetic homogeneous preparations, not only simple studies on structure-activity relationships but precise and detailed analyses became possible on how this typical bacterial component is recognized by the innate immune receptor complex of mammalian cells. 相似文献